Outcomes of Research or Clinical Trials Activity Levels Acute Flaccid Paralysis Ageing Anaerobic Threshold Anaesthesia Assistive Technology Brain Cardiorespiratory Cardiovascular Clinical Evaluation Cold Intolerance Complementary Therapies Continence Coping Styles and Strategies Cultural Context Diagnosis and Management Differential Diagnosis Drugs Dysphagia Dysphonia Epidemiology Exercise Falls Fatigue Fractures Gender Differences Immune Response Inflammation Late Effects of Polio Muscle Strength Muscular Atrophy Orthoses Pain Polio Immunisation Post-Polio Motor Unit Psychology Quality of Life Renal Complications Respiratory Complications and Management Restless Legs Syndrome Sleep Analaysis Surgery Vitality Vocational Implications

Title order Author order Journal order Date order
Category: Post-Polio Motor Unit

Title: A long-term follow-up study of patients with post-poliomyelitis neuromuscular symptoms
Author: Dalakas MC, Elder G, Hallett M, Ravits J, Baker M, Papadopoulos N, Albrecht P, Sever J
Affiliation: Not stated
Journal: The New England Journal of Medicine
Citation: N Engl J Med. 1986 Apr 10; 314(15):959-63
Publication Year and Month: 1986 04

Abstract: A “post-polio” syndrome characterized by new neuromuscular symptoms, including muscle weakness, may develop years after recovery from acute paralytic poliomyelitis. We studied 27 patients (mean age, 50.6 years) in whom new muscle weakness developed a mean of 28.8 years after recovery from acute polio. We reevaluated these patients during a mean follow-up period of 8.2 years (range, 4.5 to 20) after they were originally studied at the National Institutes of Health. The total mean follow-up period after the onset of new weakness was 12.2 years (range, 6 to 29). The patients were assessed with quantitative muscle testing, muscle biopsy, electromyography, and virologic and immunologic examination of the cerebrospinal fluid. Muscle strength had declined in all patients. The rate of decline averaged 1 percent per year. The decrease was irregular, with subjective plateau periods that ranged from 1 to 10 years. None of the patients had amyotrophic lateral sclerosis. Oligoclonal bands (IgG) were found in the cerebrospinal fluid of 7 of 13 patients studied, but no specific elevation of antibodies to poliovirus was observed in the cerebrospinal fluid. The newly affected muscles that were evaluated longitudinally with follow-up muscle biopsies and electromyography showed signs of chronic and new denervation. Groups of atrophic muscle fibers (group atrophy) and "neurogenic jitter" were not present. New post-polio muscle weakness is not a life-threatening form of motor-neuron deterioration. It appears that this weakness is not due to a loss of whole motor neurons, as in amyotrophic lateral sclerosis, but that it is due to a dysfunction of the surviving motor neurons that causes a slow disintegration of the terminals of individual nerve axons.

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Category: Post-Polio Motor Unit

Title: A rat model of the post-polio motor unit
Author: Pachter BR, Eberstein A
Affiliation: Department of Rehabilitation Medicine, New York University Medical Center, NY 10016
Journal: Orthopedics
Citation: Orthopedics. 1991 Dec; 14(12):1367-73
Publication Year and Month: 1991 12

Abstract: We examined the long-term effects of muscle usage on a rat model of the post-polio motor unit. Isometric tensions, type I and type II muscle fiber areas, the incidence of collateral sprouting, and motor endplate morphology were examined following 1, 3, 6, and 9 months of partial denervation in rat plantaris muscle. Full morphologic and functional stability of the expanded motor units occurred at 6 months post-partial denervation. Fiber hypertrophy was observed, possibly the result of compensatory work hypertrophy due to muscle overuse. Following 9 months of partial denervation and muscle overuse, the twitch and tetanic tensions and type I and type II muscle fiber areas were significantly reduced as compared to sham controls; angulated myofibers and group atrophy also were seen. The percent collateral sprouting, the number of terminal branches per endplate, and the endplate area were all increased, possibly a compensatory response to a decreased synthesis of neurotrophic factor(s) and/or transmitter-related components. These aging-like changes seem to occur earlier in chronically stressed, overenlarged, and overworked motor units.

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Category: Post-Polio Motor Unit

Title: Acute and latent effect of poliomyelitis on the motor unit as revealed by electromyography
Author: Wiechers DO
Affiliation: Not stated
Journal: Orthopedics
Citation: Orthopedics. 1985 Jul; 8(7):870-2
Publication Year and Month: 1985 07

Abstract: When polio virus attacks the motor neuron it may be completely destroyed, damaged, or unaffected. Muscle fibers of a destroyed motor neuron are orphaned or reinnervated. Nearby functioning motor units will then send terminal axon sprouts to reinnervate the orphaned muscle fibers. If there are too many orphaned muscle fibers and not enough surviving motor units to reinnervate them, the orphaned muscle fibers will continue to fibrillate until they atrophy and die. The resultant effect of poliomyelitis upon the affected muscle is an overall loss of motor units with the remaining units innervating many more muscle fibers than they originally did. There appears to be a late effect of polio upon these larger reinnervated motor units. After approximately 20 to 30 years, impulse transmission to the muscle fibers of the large reinnervated motor unit begins to fail. These transmission difficulties increase with age and time from recovery. These late onset transmission abnormalities may be factors in patient complaints of fatigue and progressive weakness.

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Category: Muscular Atrophy, Post-Polio Motor Unit

Title: An autopsy case of progressive generalized muscle atrophy over 14 years due to post-polio syndrome
Author: Oki R (1), Uchino A, Izumi Y, Ogawa H, Murayama S, Kaji R
Affiliation: (1) Department of Clinical Neuroscience, Institute of Health Bioscience, University of Tokushima Graduate School
Journal: Rinsho Shinkeigaku (Clinical Neurology)
Citation: Rinsho Shinkeigaku. 2015 Nov 30
Publication Year and Month: 2015 11

Abstract: We report the case of a 72-year-old man who had contracted acute paralytic poliomyelitis in his childhood. Thereafter, he had suffered from paresis involving the left lower limb, with no relapse or progression of the disease. He began noticing slowly progressive muscle weakness and atrophy in the upper and lower extremities in his 60s. At the age of 72, muscle weakness developed rapidly, and he demonstrated dyspnea on exertion and dysphagia. He died after about 14 years from the onset of muscle weakness symptoms. Autopsy findings demonstrated motoneuron loss and glial scars not only in the plaque-like lesions in the anterior horns, which were sequelae of old poliomyelitis, but also throughout the spine. No Bunina bodies, TDP-43, and ubiquitin inclusions were found. Post-polio syndrome is rarely fatal due to rapid progressive dyspnea and dysphagia. Thus, the pathological findings in the patient are considered to be related to the development of muscle weakness.

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Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Correlation of Electrophysiology with Pathology, Pathogenesis, and Anticholinesterase Therapy in Post-Polio Syndrome
Author: Neil R. Cashman and Daria A. Trojan
Affiliation: Department of Neurology, Montreal Neurological Institute and Hospital, McGill University
Journal: Annals of the New York Academy of Sciences
Citation: Reprinted from The Post-Polio Syndrome: Advances in the Pathogenesis and Treatment
Volume 753 [pp 138-150] of the Annals of the New York Academy of Sciences
May 25, 1995
Publication Year and Month: 1995 05

Abstract:

Conclusions: A great deal of data has been generated on PPS, and a great deal more will be generated before we understand the pathophysiology of this common and disabling disorder. Perhaps now, to guide future work and direct therapeutic approaches, it is best to think of the symptoms of PPS as due to two lesions of the motor unit: a "progressive lesion" and a "fluctuating lesion." The progressive lesion gives rise to the symptom of slowly progressive weakness, and is due to the degeneration of terminal axons (and perhaps motor neurons) over the course of years. This lesion, best articulated by Wiechers and Hubble,[18] has been difficult to objectify because of its indolent nature. However, significant clinical weakening has indeed been quantified by several groups, including Munsat and colleagues,[7] and Sonies and Dalakas.[53] The best objective "proof" of the progressive lesion at present is the appearance of muscle fiber atrophy in biopsies, isolated and in groups, suggesting ongoing "permanent" denervation.[22] Diminution of motor unit size over time, as suggested by the macro-EMG studies of Lange et al.,[32] are also consistent with this hypothesis, albeit more controversial.

The other lesion of the PPS motor unit, hypothesized as a "fluctuating lesion," may be due to dysfunction of terminal axons, which gives rise to symptoms (muscle fatigability, generalized fatigue, and a component of weakness) that can change over the course of minutes to days. The underlying pathophysiology of these symptoms may be due to critical enlargement of motor units with limitations of distal components subserving axonal conduction and NMJ transmission, and/or the constant remodeling of the motor unit which appears to occur in virtually every individual after recovery from paralytic poliomyelitis. The best objective evidence for this ongoing lesion is provided by innumerable electrophysiologic studies demonstrating unstable motor unit action potentials and decrement on repetitive stimulation with conventional EMG, increased SFEMG jitter, and a host ofother studies.[54] In addition, the widespread expression of N-CAM in muscle biopsies of post-polio subjects (sometimes exceeding 10% of fibers)[22] strongly suggests that axono-myofiber interactions are distinctly unstable and/or immature. Clearly, agents that support the integrity or function of motor axonal sprouts may improve or delay patient symptoms in PPS.

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Dynamic electromyography and muscle biopsy changes in a 4-year follow-up: study of patients with a history of polio
Author: Stålberg E, Grimby G
Affiliation: Department of Clinical Neurophysiology, University Hospital, Uppsala, Sweden
Journal: Muscle & Nerve
Citation: Muscle Nerve. 1995 Jul;18(7):699-707
Publication Year and Month: 1995 07

Abstract: Eighteen patients who had had polio 29-56 years prior to the first investigation were studied on two occasions, 4 years apart. Isokinetic and isometric strength measurements and Macro EMG were performed in 28 legs. Muscle biopsy specimens were obtained on both occasions from 11 legs. On average the muscle strength was 56% of control values at the first examination, and decreased by another 8% during the observation period. The muscle fiber area was increased compared to that of controls and did not change significantly. Macro EMG, comprising muscle fiber area and number of muscle fibers, and/or single fiber EMG showed clear signs of reinnervation in all legs. The motor units at the first examination were increased 11-fold, on average, compared with age-matched control values. During the observation period, reinnervation continued and the size of motor units increased by another 56% as a result of ongoing denervation, that is, loss of neurons. This compensation was particularly pronounced in patients with stable conditions. The parameters studied did not reveal any definite pattern predicting future development of new muscle weakness in individual subjects.

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Category: Post-Polio Motor Unit

Title: Electrodiagnostic Findings in 108 Consecutive Patients Referred to a Post-Polio Clinic – The Value of Routine Electrodiagnostic Studies
Author: Anne C. Gawne, Bao T. Pham, and Lauro S. Halstead

Affiliation:
Journal: Annals of the New York Academy of Sciences
Citation: The Post-Polio Syndrome: Advances in the Pathogenesis and Treatment Volume 753 pp 383-385 of the Annals of the New York Academy of Sciences May 25, 1995.
Publication Year and Month: 1995 05

Abstract: Many patients with a history of polio develop new symptoms including weakness, pain, fatigue, and changes in function, or post-polio syndrome (PPS).[1] Before a diagnosis of PPS is made, other diagnoses must first be ruled out. Assessment must be done in a comprehensive and coordinated manner.[2] Therefore, as part of our routine evaluation, we do an electromyogram/nerve conduction study (EMG/NCS) on every patient. During examinations on our clinic patients we began to notice (1) electrodiagnostic evidence of polio in limbs not previously felt to be involved; (2) a normal EMG, or evidence of another disease; and (3) EMG evidence consistent with additional neurological lesions, including compression neuropathies, peripheral neuropathies, and radiculopathies. A prospective study using a routine, standardized four-extremity electrodiagnostic protocol was done to quantify the frequency of these occurrences.

Conclusions: Our findings strongly support the value of a standardized four-extremity EMG/NCS as an adjuvant to a comprehensive history and physical examination. It helps to differentiate between old polio and other neurological diagnoses. There is a high prevalence of subclinical polio, which is important to know about in order to give proper recommendations regarding rest and activity. Given the frequency of risk factors for development of potentially treatable neurological lesions like CTS, early detection is valuable. We believe routine electrodiagnostic testing is essential for proper evaluation and management of the post-polio patient.

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Category: Post-Polio Motor Unit

Title: Electromyographic and morphological functional compensation in late poliomyelitis
Author: Einarsson G, Grimby G, Stålberg E
Affiliation: Department of Rehabilitation Medicine, Gothenburg University, Sweden
Journal: Muscle & Nerve
Citation: Muscle Nerve. 1990 Feb; 13(2):165-71
Publication Year and Month: 1990 02

Abstract: Patients with prior poliomyelitis may experience muscle function deterioration decades after onset of disease. The present study is aimed at describing electromyographic and morphometric evidence of muscular compensation and of on-going muscular instability. Ten subjects 42-62 years of age with onset of polio 25-52 years earlier were studied with macro EMG, single-fiber EMG (SFEMG), muscle strength measurement, and morphometrical analysis of muscle biopsies from the vastus lateralis muscle. SFEMG revealed increased fiber density (FD) and large macro-MUP potentials indicating pronounced reinnervation as compensation to loss of motor neurons. From electrophysiological data of motor unit size, morphometric measures of fiber size, and muscle strength data, the minimal degree of motor neuron loss was estimated to be greater than 70%.

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Category: Post-Polio Motor Unit

Title: Electrophysiology and Electrodiagnosis of the Post-Polio Motor Unit
Author: Daria A. Trojan, MD, Daniel Gendron, MD, Neil R. Cashman, MD
Affiliation:
Journal: Orthopedics
Citation: Orthopedics December 1991 Vol 14 No 12 1353-1361
Publication Year and Month: 1991 12

Abstract: Post-poliomyelitis syndrome refers to new symptoms that may occur years after recovery from poliomyelitis. The most common of these symptoms are new weakness, fatigue, and pain. This article describes electrodiagnostic studies -- conventional electromyography (EMG), single fiber electromyography (SFEMG), and macroelectromyography (macro-EMG) -- that have provided information on the post-polio motor unit and on the possible etiology of some post-polio syndrome symptoms. Muscular fatigue, and indirectly, general fatigue, may be due to neuromuscular junction transmission defects in some post-polio individuals, as suggested by reduction of the compound motor action potentials on repetitive stimulation, and increased jitter and blocking on SFEMG. Progressive weakness and atrophy in post-polio syndrome is probably due to a distal degeneration of post-polio motor units with resultant irreversible muscle fiber denervation. Electrodiagnostic evidence of ongoing denervation includes fibrillation and fasciculation potentials on conventional EMG, increased jitter and blocking on SFEMG, and smaller macro-EMG amplitudes in newly weakened postpolio muscles. However, even though electrodiagnostic studies have provided insight into the possible causes of some postpolio syndrome symptoms, no specific electrodiagnostic test for the syndrome is currently available.

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Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Functional recovery – a major risk factor for the development of postpoliomyelitis muscular atrophy
Author: Klingman J, Chui H, Corgiat M, Perry J
Affiliation: Department of Neurology, University of Southern California School of Medicine, Los Angeles
Journal: Archives of Neurology
Citation: Arch Neurol. 1988 Jun;45(6):645-7
Publication Year and Month: 1988 06

Abstract: A retrospective study was undertaken to identify potential risk factors for the development of progressive postpoliomyelitis muscular atrophy (PPMA). Patients with PPMA (n = 57) were compared with patients with a history of poliomyelitis but without a history of progressive weakness (n = 49). Patients who later developed PPMA had histories of more widespread acute paralysis, but relatively greater functional recovery. They were less disabled, and reported higher recent activity levels. Seventy-nine percent of the total variance between the PPMA and control groups could be accounted for by recovery alone (ie, severity minus disability). Functional recovery is generally attributed to reinnervation of sarcomeres by collateral sprouting from surviving lower motor neurons. Since degree of recovery predicts the risk of developing PPMA, our findings suggest that enlarged motor units may carry an increased susceptibility for dysfunction and/or degeneration.

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Category: Post-Polio Motor Unit

Title: Late denervation in patients with antecedent paralytic poliomyelitis
Author: Cashman NR, Maselli R, Wollmann RL, Roos R, Simon R, Antel JP
Affiliation: Not stated
Journal: The New England Journal of Medicine
Citation: N Engl J Med. 1987 Jul 2; 317(1):7-12
Publication Year and Month: 1987 07

Abstract: The development of new weakness, fatigue, and pain decades after acute paralytic poliomyelitis is a recognized syndrome. We conducted a controlled study of this syndrome by analyzing clinical, electromyographic, and muscle-biopsy features in 18 patients with a history of poliomyelitis--13 reporting 1 to 20 years of new weakness and 5 without new symptoms. The patients with new weakness also reported new muscle atrophy (9 of 13) and fatigue (10 of 13), symptoms not reported by the controls. The age at the time of acute poliomyelitis, severity of poliomyelitis, residual disability, number of years since acute poliomyelitis, and age at the time of study were comparable in the weakening and control groups. Evidence of remote denervation consistent with antecedent poliomyelitis was demonstrated in all patients by electromyography or muscle biopsy or both. In addition, active denervation (as evidenced by spontaneous activity on conventional electromyography, increased jitter on single-fiber electromyography, or atrophic myofibers) was found in 12 patients in the weakening group and in all 5 controls. Immunohistochemical detection of myofibers expressing the neural-cell adhesion molecule corroborated ongoing denervation in both patient groups. When muscle data from both groups were pooled, correlations were observed between the extent of past reinnervation and the degree of ongoing motor-unit instability. We conclude that the extensive reinnervation of denervated muscle that occurs in paralytic poliomyelitis may be followed by late denervation of the previously reinnervated muscle fibers. Electromyographic and muscle-biopsy evidence of ongoing denervation does not distinguish between stable patients with prior paralytic poliomyelitis and those with new weakness.

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Category: Post-Polio Motor Unit

Title: Late effects of polio: critical review of the literature on neuromuscular function
Author: Agre JC, Rodríquez AA, Tafel JA
Affiliation: University of Wisconsin - Madison Medical School
Journal: Archives of Physical Medicine and Rehabilitation
Citation: Arch Phys Med Rehabil. 1991 Oct; 72(11):923-31
Publication Year and Month: 1991 10

Abstract: Many individuals who have had poliomyelitis are now complaining of several new problems attributed to their former illness including muscle atrophy; fatigue; progressive weakness; and muscle, back, and joint pain. This paper critically examines the literature regarding the neuromuscular effects of poliomyelitis. Weakness resulting from poliomyelitis was due to destruction of anterior horn cells. After the illness, muscle strength was partially recovered as a result of several physiologic adaptive mechanisms including terminal sprouting and reinnervation, myofiber hypertrophy, and, possibly, myofiber type transformation. Several pathophysiologic and functional etiologies have been proposed for late neuromuscular deterioration, but none has been proven. In fact, to date, there is no objective evidence documenting progressive loss of strength in polio survivors. Studies attempting to differentiate polio survivors with and without symptoms of deterioration have resulted in conflicting results; however, it appears reasonable to conclude that symptomatic postpolio subjects had a more severe illness with greater loss of neuromuscular function. Exercise may be helpful for many postpolio patients, but the prescription must be tailored to the individual to avoid problems of overuse or excessive fatigue.

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Category: Post-Polio Motor Unit

Title: Loss of motor unit size and quadriceps strength over 10 years in post-polio syndrome
Author: Bickerstaffe A (1), van Dijk JP (2), Beelen A (3), Zwarts MJ (4), Nollet F (5)
Affiliation: (1) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]; (2) Radboud University Nijmegen Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Department of Neurology/Clinical Neurophysiology, Postbus 910, 6500 HB Nijmegen, The Netherlands; Epilepsy Centre Kempenhaeghe, Postbus 61, 5590 AB Heeze, The Netherlands. Electronic address: [email protected]; (3) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]; (4) Epilepsy Centre Kempenhaeghe, Postbus 61, 5590 AB Heeze, The Netherlands. Electronic address: [email protected]; (5) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]
Journal: Clinical Neurophysiology
Citation: Clin Neurophysiol. 2014 Jun;125(6):1255-60. doi: 10.1016/j.clinph.2013.11.003
Publication Year and Month: 2014 06

Abstract: OBJECTIVE: To investigate whether strength decline in post-polio syndrome (PPS) results from excessive distal axonal degeneration of enlarged motor units.

METHODS: We assessed changes over 10 years in isometric quadriceps strength, mean motor unit action potential (MUAP) size, root mean squared (RMS) amplitude, and level of interference (LOI) in 47 patients with PPS and 12 healthy controls, using high density surface EMG. At baseline, all patients had symptomatic quadriceps dysfunction, evidenced by transmission defects on single-fibre EMG.

RESULTS: MU size and strength declined significantly by 20% and 15%, respectively in patients with PPS. Those with the largest initial MU sizes exhibited the greatest losses of mean MU size (27%) and proportional decreases in quadriceps strength (23%). Initial strength, change in LOI and change in RMS amplitude together explained 35% of the variability in strength changes in patients. MU size of controls did not change, although they lost 29% strength.

SIGNIFICANCE: This long term follow-up study provides evidence that size diminution of enlarged MUs combined with a reduced number of active MUs contributes to the gradual strength decline in PPS.

Conclusions: MU size and strength declined concomitantly in a homogeneous cohort of patients with PPS and quadriceps dysfunction.

Outcome of Research: Effective

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Category: Post-Polio Motor Unit

Title: Muscle Function, Muscle Structure, and Electrophysiology in a Dynamic Perspective in Late Polio
Author: Gunnar Grimby, MD, PhD, Erik Stålberg, MD.
Affiliation:
Journal: NEW - PUT DETAILS IN CITATION FIELD
Citation: Gunnar Grimby, MD, PhD, Erik Stålberg, MD., Muscle Function, Muscle Structure, and Electrophysiology in a Dynamic Perspective in Late Polio, Chapter 2, pp 15-24.
Publication Year and Month: 1995

Abstract: The muscular impairment in patients with a history of polio varies from none to severe. The relationship between the degree of initial involvement and the effect of various compensatory mechanisms determines the clinical picture, which changes dynamically. Early and late recovery after poliomyelitis depend on a number of factors. Clinical improvement that appears within a few weeks after the acute phase is probably due to recovery in the excitability of functional, but not degenerated, motor neurons. Degeneration of neurons, causing peripheral denervation, is compensated by collateral sprouting, i.e., by nerve twigs branching off from surviving motor units overlapping with the denervated ones. This is most likely the main factor explaining recovery within the first 6-12 months. Another late compensatory process is the increase in size of the muscle fibers. As a result of these processes, normal muscle strength and presumably normal muscle volume can be seen despite a calculated loss exceeding 50% of the number of motor neurons.

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Category: Post-Polio Motor Unit

Title: Neurological manifestations of the post-polio syndrome
Author: Jubelt B, Cashman NR
Affiliation: Les Turner Amyotrophic Lateral Sclerosis Research Laboratory, Northwestern University Medical School, Chicago, Illinois
Journal: Critical Reviews in Neurobiology
Citation: Crit Rev Neurobiol. 1987;3(3):199-220
Publication Year and Month: 1987 03

Abstract: Patients with late effects of poliomyelitis, ie PPS, are being seen at an ever increasing frequency by general physicians, neurologists, and orthopedists. An appropriate time interval for the onset of late manifestations has elapsed since the major epidemics of poliomyelitis in the 1940s and 1950s. Post-polio neurological manifestations primarily include new weakness, atrophy, muscle pain, and fasciculations. Fortunately, the weakness is of a very slow, progressive nature. Abnormal laboratory studies include routine EMG, demonstrating chronic denervation; SFEMG, demonstrating increased fiber density, increased jitter, and blocking; and muscle biopsy most often revealing fiber-type grouping of chronic denervation and small isolated angular (or angulated) fibers and group atrophy in some series, both suggestive of active denervation. Unfortunately, both EMG and muscle biopsy studies suffer from a lack of specificity as they do not appear to distinguish asymptomatic from symptomatic (new weakness, PPMA) patients with prior poliomyelitis. Although the cause of PPMA is unknown, electrophysiological (SFEMG) and muscle biopsy studies suggest that the process involves a loss or dropout of axon terminals of reinnervated motor units. The axons terminal dropout could be due to dysfunction in the cell soma, the axon, or the terminals themselves. Whether motor neuron exhaustion, a persistent viral infection, or immune-mediated mechanisms play a role in the pathogenesis of the late weakness is unclear at present and will require further investigation. Treatment at this time is of a supportive nature. A major controversy involves the role of strengthening exercises in these patients since experimental animal studies suggest that excessive exercise of denervated muscles leads to increased weakness. Clearly, a better understanding of PPS and PPMA will allow more effective management of these patients’ problems and might also provide insight into other motor neuron and neuromuscular junction diseases.

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Category: Post-Polio Motor Unit

Title: Polioencephalitis and the Brain Fatigue Generator Model of Post-Viral Fatigue Syndromes
Author: Richard L. Bruno, Ph.D., Nancy M. Frick, Lh.D., Susan Creange, M.A., Jerald R. Zimmerman, M.D., and Todd Lewis, Ph.D.


Affiliation: Post-Polio Rehabilitation and Research Service; Kessler Institute for Rehabilitation, Department of Physical Medicine and Rehabilitation; UMDNJ/New Jersey Medical School, Harvest Center; Hackensack, New Jersey
Journal:
Citation: Journal of Chronic Fatigue Syndrome, 1996; Department of Physical Medicine and Rehabilitation (in press)
Publication Year and Month: 1996

Abstract: Fatigue is the most commonly reported and most debilitating Post-Polio Sequelae (PPS) affecting millions of polio survivors world-wide. Post-polio fatigue is associated with: 1) subjective reports of difficulty with attention, cognition, word-finding and maintaining wakefulness; 2) clinically significant deficits on neuropsychological tests of information processing speed and attention; 3) gray and white matter hyperintensities in the reticular activating system on magnetic resonance imaging of the brain; 4) neuroendocrine evidence of impaired activation of the HPA axis. Many of these findings are identical to those documented following a variety of viral encephalitides, including acute poliovirus infection, lethargic encephalitis, Iceland Disease, myalgic encephalomyelitis, and, most recently, Chronic Fatigue Syndrome. The clinical, historic, neuropsychologic, neuroanatomic and physiologic parallels between poliovirus infection, post-polio fatigue and post-viral fatigue syndromes (PVFS) will be explored in an attempt to describe the pathophysiology of PVFS. The disinhibition of a putative Brain Fatigue Generator will be implicated as a cause of the subjective symptoms and objective signs that accompany PVFS. The results of a pilot placebo-controlled study of a dopamine 2 receptor agonist to treat post-polio fatigue will also be described.

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Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Repeater F-waves are signs of motor unit pathology in polio survivors
Author: Hachisuka A (1), Komori T, Abe T, Hachisuka K
Affiliation: (1) Department of Rehabilitation Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi, Kitakyushu, 807-8555, Japan
Journal: Muscle & Nerve
Citation: Muscle Nerve. 2015 May;51(5):680-5. doi: 10.1002/mus.24428
Publication Year and Month: 2015 05

Abstract: INTRODUCTION: The purpose of this study was to determine whether F-waves reveal electrophysiological features of anterior horn cells in polio survivors.

METHODS: Forty-three polio survivors and 20 healthy controls underwent motor nerve conduction studies of the median and tibial nerves bilaterally, including sampling of F-waves elicited by 100 stimuli and the determination of motor unit number estimation (MUNE).

RESULTS: A significant increase in abnormally stereotyped ("repeater") F-waves and a reduction of F-wave persistence were observed in both nerves in the polio group as compared with the control group. Repeater F-waves had a negative correlation with MUNE.

Conclusions: These trends in F-wave persistence and repeater F-waves after motor unit loss are characteristic findings in polio survivors. Repeater F-waves are a sign of motor unit pathology.

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Stimulation frequency-dependent neuromuscular junction transmission defects in patients with prior poliomyelitis
Author: Daria A. Trojan, Daniel Gendron and Neil R. Cashman
Affiliation: Department of Neurology, McGill University, Montreal Neurological Institute and Hospital
Journal:
Citation: Journal of the Neurological Sciences, 118 (1993) 150-157
Publication Year and Month: 1993 03

Abstract: Generalized fatigue and muscle fatiguability are major symptoms of post-poliomyelitis syndrome (PPS), and may be due to neuromuscular junction transmission defects, as suggested by increased jitter on single fiber electromyography (SFEMG). To determine the etiology of this defect, we studied jitter at low (1, 5 Hz) and high (10, 15, 20 Hz) frequency stimulation with stimulation SFEMG in 17 post-polio patients with muscle fatiguability, and in 9 normal controls. In 5 of 17 PPS patients and in 1 of 9 controls, jitter was significantly higher (unpaired t-test, P < 0.05) at high frequency stimulation (HFS). In the remaining PPS patients and controls there was no significant difference in jitter at high and low stimulation frequencies. PPS patients with increased jitter at HFS had a significantly longer time interval since acute polio (mean 48.5 years) than PPS patients without increased jitter at HFS (mean 40 years; P < 0.05), but were not distinguished by other historical or clinical criteria. We conclude that the neuromuscular junction defect in post-polio patients is similar to that observed in amyotrophic lateral sclerosis, and is probably due to ineffective conduction along immature nerve sprouts and exhaustion of acetylcholine stores. The appearance of an increase in jitter with HFS in post-polio patients may be dependent upon time after acute polio.

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Category: Post-Polio Motor Unit

Title: Vasomotor abnormalities as post-polio sequelae: functional and clinical implications
Author: Bruno RL, Johnson JC, Berman WS
Affiliation: Not stated
Journal: Orthopedics
Citation: Orthopedics. 1985 Jul; 8(7):865-9
Publication Year and Month: 1985 07

Abstract: Persons who had poliomyelitis report cold and discolored extremities and decreased muscle strength when exposed to mildly cool ambient temperatures. Bilateral digital cutaneous blood flow, skin temperature and median nerve latencies and amplitudes were measured at 30 degrees C, 25 degrees C and 20 degrees C in five post-polio subjects and age-matched controls. Cutaneous blood flow was lowest on the more affected side in the post-polio subjects but vasoconstriction with decreasing Ta was equal bilaterally in both groups. With decreasing Ta, median motor nerve latencies became clinically abnormal and “giant” sensory nerve potential amplitudes were seen in a majority of the post-polio subjects. It is concluded that an impairment of sympathetic vasoconstrictor outflow in post-polios allows passive dilatation and engorgement of the cutaneous venous capacitance beds. This promotes uncontrolled heat loss and causes cooling of nerve and muscle that is responsible for the impairment of muscle functioning and the abnormal electrophysiological findings.

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Category: Post-Polio Motor Unit

Title: Late effects of polio: critical review of the literature on neuromuscular function
Author: Agre JC, Rodríquez AA, Tafel JA
Affiliation: University of Wisconsin - Madison Medical School
Journal: Archives of Physical Medicine and Rehabilitation
Citation: Arch Phys Med Rehabil. 1991 Oct; 72(11):923-31
Publication Year and Month: 1991 10

Abstract: Many individuals who have had poliomyelitis are now complaining of several new problems attributed to their former illness including muscle atrophy; fatigue; progressive weakness; and muscle, back, and joint pain. This paper critically examines the literature regarding the neuromuscular effects of poliomyelitis. Weakness resulting from poliomyelitis was due to destruction of anterior horn cells. After the illness, muscle strength was partially recovered as a result of several physiologic adaptive mechanisms including terminal sprouting and reinnervation, myofiber hypertrophy, and, possibly, myofiber type transformation. Several pathophysiologic and functional etiologies have been proposed for late neuromuscular deterioration, but none has been proven. In fact, to date, there is no objective evidence documenting progressive loss of strength in polio survivors. Studies attempting to differentiate polio survivors with and without symptoms of deterioration have resulted in conflicting results; however, it appears reasonable to conclude that symptomatic postpolio subjects had a more severe illness with greater loss of neuromuscular function. Exercise may be helpful for many postpolio patients, but the prescription must be tailored to the individual to avoid problems of overuse or excessive fatigue.

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Category: Post-Polio Motor Unit

Title: Electrodiagnostic Findings in 108 Consecutive Patients Referred to a Post-Polio Clinic – The Value of Routine Electrodiagnostic Studies
Author: Anne C. Gawne, Bao T. Pham, and Lauro S. Halstead

Affiliation:
Journal: Annals of the New York Academy of Sciences
Citation: The Post-Polio Syndrome: Advances in the Pathogenesis and Treatment Volume 753 pp 383-385 of the Annals of the New York Academy of Sciences May 25, 1995.
Publication Year and Month: 1995 05

Abstract: Many patients with a history of polio develop new symptoms including weakness, pain, fatigue, and changes in function, or post-polio syndrome (PPS).[1] Before a diagnosis of PPS is made, other diagnoses must first be ruled out. Assessment must be done in a comprehensive and coordinated manner.[2] Therefore, as part of our routine evaluation, we do an electromyogram/nerve conduction study (EMG/NCS) on every patient. During examinations on our clinic patients we began to notice (1) electrodiagnostic evidence of polio in limbs not previously felt to be involved; (2) a normal EMG, or evidence of another disease; and (3) EMG evidence consistent with additional neurological lesions, including compression neuropathies, peripheral neuropathies, and radiculopathies. A prospective study using a routine, standardized four-extremity electrodiagnostic protocol was done to quantify the frequency of these occurrences.

Conclusions: Our findings strongly support the value of a standardized four-extremity EMG/NCS as an adjuvant to a comprehensive history and physical examination. It helps to differentiate between old polio and other neurological diagnoses. There is a high prevalence of subclinical polio, which is important to know about in order to give proper recommendations regarding rest and activity. Given the frequency of risk factors for development of potentially treatable neurological lesions like CTS, early detection is valuable. We believe routine electrodiagnostic testing is essential for proper evaluation and management of the post-polio patient.

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Category: Post-Polio Motor Unit

Title: Loss of motor unit size and quadriceps strength over 10 years in post-polio syndrome
Author: Bickerstaffe A (1), van Dijk JP (2), Beelen A (3), Zwarts MJ (4), Nollet F (5)
Affiliation: (1) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]; (2) Radboud University Nijmegen Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Department of Neurology/Clinical Neurophysiology, Postbus 910, 6500 HB Nijmegen, The Netherlands; Epilepsy Centre Kempenhaeghe, Postbus 61, 5590 AB Heeze, The Netherlands. Electronic address: [email protected]; (3) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]; (4) Epilepsy Centre Kempenhaeghe, Postbus 61, 5590 AB Heeze, The Netherlands. Electronic address: [email protected]; (5) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]
Journal: Clinical Neurophysiology
Citation: Clin Neurophysiol. 2014 Jun;125(6):1255-60. doi: 10.1016/j.clinph.2013.11.003
Publication Year and Month: 2014 06

Abstract: OBJECTIVE: To investigate whether strength decline in post-polio syndrome (PPS) results from excessive distal axonal degeneration of enlarged motor units.

METHODS: We assessed changes over 10 years in isometric quadriceps strength, mean motor unit action potential (MUAP) size, root mean squared (RMS) amplitude, and level of interference (LOI) in 47 patients with PPS and 12 healthy controls, using high density surface EMG. At baseline, all patients had symptomatic quadriceps dysfunction, evidenced by transmission defects on single-fibre EMG.

RESULTS: MU size and strength declined significantly by 20% and 15%, respectively in patients with PPS. Those with the largest initial MU sizes exhibited the greatest losses of mean MU size (27%) and proportional decreases in quadriceps strength (23%). Initial strength, change in LOI and change in RMS amplitude together explained 35% of the variability in strength changes in patients. MU size of controls did not change, although they lost 29% strength.

SIGNIFICANCE: This long term follow-up study provides evidence that size diminution of enlarged MUs combined with a reduced number of active MUs contributes to the gradual strength decline in PPS.

Conclusions: MU size and strength declined concomitantly in a homogeneous cohort of patients with PPS and quadriceps dysfunction.

Outcome of Research: Effective

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Category: Post-Polio Motor Unit

Title: Vasomotor abnormalities as post-polio sequelae: functional and clinical implications
Author: Bruno RL, Johnson JC, Berman WS
Affiliation: Not stated
Journal: Orthopedics
Citation: Orthopedics. 1985 Jul; 8(7):865-9
Publication Year and Month: 1985 07

Abstract: Persons who had poliomyelitis report cold and discolored extremities and decreased muscle strength when exposed to mildly cool ambient temperatures. Bilateral digital cutaneous blood flow, skin temperature and median nerve latencies and amplitudes were measured at 30 degrees C, 25 degrees C and 20 degrees C in five post-polio subjects and age-matched controls. Cutaneous blood flow was lowest on the more affected side in the post-polio subjects but vasoconstriction with decreasing Ta was equal bilaterally in both groups. With decreasing Ta, median motor nerve latencies became clinically abnormal and “giant” sensory nerve potential amplitudes were seen in a majority of the post-polio subjects. It is concluded that an impairment of sympathetic vasoconstrictor outflow in post-polios allows passive dilatation and engorgement of the cutaneous venous capacitance beds. This promotes uncontrolled heat loss and causes cooling of nerve and muscle that is responsible for the impairment of muscle functioning and the abnormal electrophysiological findings.

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Category: Post-Polio Motor Unit

Title: Late denervation in patients with antecedent paralytic poliomyelitis
Author: Cashman NR, Maselli R, Wollmann RL, Roos R, Simon R, Antel JP
Affiliation: Not stated
Journal: The New England Journal of Medicine
Citation: N Engl J Med. 1987 Jul 2; 317(1):7-12
Publication Year and Month: 1987 07

Abstract: The development of new weakness, fatigue, and pain decades after acute paralytic poliomyelitis is a recognized syndrome. We conducted a controlled study of this syndrome by analyzing clinical, electromyographic, and muscle-biopsy features in 18 patients with a history of poliomyelitis--13 reporting 1 to 20 years of new weakness and 5 without new symptoms. The patients with new weakness also reported new muscle atrophy (9 of 13) and fatigue (10 of 13), symptoms not reported by the controls. The age at the time of acute poliomyelitis, severity of poliomyelitis, residual disability, number of years since acute poliomyelitis, and age at the time of study were comparable in the weakening and control groups. Evidence of remote denervation consistent with antecedent poliomyelitis was demonstrated in all patients by electromyography or muscle biopsy or both. In addition, active denervation (as evidenced by spontaneous activity on conventional electromyography, increased jitter on single-fiber electromyography, or atrophic myofibers) was found in 12 patients in the weakening group and in all 5 controls. Immunohistochemical detection of myofibers expressing the neural-cell adhesion molecule corroborated ongoing denervation in both patient groups. When muscle data from both groups were pooled, correlations were observed between the extent of past reinnervation and the degree of ongoing motor-unit instability. We conclude that the extensive reinnervation of denervated muscle that occurs in paralytic poliomyelitis may be followed by late denervation of the previously reinnervated muscle fibers. Electromyographic and muscle-biopsy evidence of ongoing denervation does not distinguish between stable patients with prior paralytic poliomyelitis and those with new weakness.

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Category: Post-Polio Motor Unit

Title: A long-term follow-up study of patients with post-poliomyelitis neuromuscular symptoms
Author: Dalakas MC, Elder G, Hallett M, Ravits J, Baker M, Papadopoulos N, Albrecht P, Sever J
Affiliation: Not stated
Journal: The New England Journal of Medicine
Citation: N Engl J Med. 1986 Apr 10; 314(15):959-63
Publication Year and Month: 1986 04

Abstract: A “post-polio” syndrome characterized by new neuromuscular symptoms, including muscle weakness, may develop years after recovery from acute paralytic poliomyelitis. We studied 27 patients (mean age, 50.6 years) in whom new muscle weakness developed a mean of 28.8 years after recovery from acute polio. We reevaluated these patients during a mean follow-up period of 8.2 years (range, 4.5 to 20) after they were originally studied at the National Institutes of Health. The total mean follow-up period after the onset of new weakness was 12.2 years (range, 6 to 29). The patients were assessed with quantitative muscle testing, muscle biopsy, electromyography, and virologic and immunologic examination of the cerebrospinal fluid. Muscle strength had declined in all patients. The rate of decline averaged 1 percent per year. The decrease was irregular, with subjective plateau periods that ranged from 1 to 10 years. None of the patients had amyotrophic lateral sclerosis. Oligoclonal bands (IgG) were found in the cerebrospinal fluid of 7 of 13 patients studied, but no specific elevation of antibodies to poliovirus was observed in the cerebrospinal fluid. The newly affected muscles that were evaluated longitudinally with follow-up muscle biopsies and electromyography showed signs of chronic and new denervation. Groups of atrophic muscle fibers (group atrophy) and "neurogenic jitter" were not present. New post-polio muscle weakness is not a life-threatening form of motor-neuron deterioration. It appears that this weakness is not due to a loss of whole motor neurons, as in amyotrophic lateral sclerosis, but that it is due to a dysfunction of the surviving motor neurons that causes a slow disintegration of the terminals of individual nerve axons.

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Category: Post-Polio Motor Unit

Title: Stimulation frequency-dependent neuromuscular junction transmission defects in patients with prior poliomyelitis
Author: Daria A. Trojan, Daniel Gendron and Neil R. Cashman
Affiliation: Department of Neurology, McGill University, Montreal Neurological Institute and Hospital
Journal:
Citation: Journal of the Neurological Sciences, 118 (1993) 150-157
Publication Year and Month: 1993 03

Abstract: Generalized fatigue and muscle fatiguability are major symptoms of post-poliomyelitis syndrome (PPS), and may be due to neuromuscular junction transmission defects, as suggested by increased jitter on single fiber electromyography (SFEMG). To determine the etiology of this defect, we studied jitter at low (1, 5 Hz) and high (10, 15, 20 Hz) frequency stimulation with stimulation SFEMG in 17 post-polio patients with muscle fatiguability, and in 9 normal controls. In 5 of 17 PPS patients and in 1 of 9 controls, jitter was significantly higher (unpaired t-test, P < 0.05) at high frequency stimulation (HFS). In the remaining PPS patients and controls there was no significant difference in jitter at high and low stimulation frequencies. PPS patients with increased jitter at HFS had a significantly longer time interval since acute polio (mean 48.5 years) than PPS patients without increased jitter at HFS (mean 40 years; P < 0.05), but were not distinguished by other historical or clinical criteria. We conclude that the neuromuscular junction defect in post-polio patients is similar to that observed in amyotrophic lateral sclerosis, and is probably due to ineffective conduction along immature nerve sprouts and exhaustion of acetylcholine stores. The appearance of an increase in jitter with HFS in post-polio patients may be dependent upon time after acute polio.

Conclusions:

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Electrophysiology and Electrodiagnosis of the Post-Polio Motor Unit
Author: Daria A. Trojan, MD, Daniel Gendron, MD, Neil R. Cashman, MD
Affiliation:
Journal: Orthopedics
Citation: Orthopedics December 1991 Vol 14 No 12 1353-1361
Publication Year and Month: 1991 12

Abstract: Post-poliomyelitis syndrome refers to new symptoms that may occur years after recovery from poliomyelitis. The most common of these symptoms are new weakness, fatigue, and pain. This article describes electrodiagnostic studies -- conventional electromyography (EMG), single fiber electromyography (SFEMG), and macroelectromyography (macro-EMG) -- that have provided information on the post-polio motor unit and on the possible etiology of some post-polio syndrome symptoms. Muscular fatigue, and indirectly, general fatigue, may be due to neuromuscular junction transmission defects in some post-polio individuals, as suggested by reduction of the compound motor action potentials on repetitive stimulation, and increased jitter and blocking on SFEMG. Progressive weakness and atrophy in post-polio syndrome is probably due to a distal degeneration of post-polio motor units with resultant irreversible muscle fiber denervation. Electrodiagnostic evidence of ongoing denervation includes fibrillation and fasciculation potentials on conventional EMG, increased jitter and blocking on SFEMG, and smaller macro-EMG amplitudes in newly weakened postpolio muscles. However, even though electrodiagnostic studies have provided insight into the possible causes of some postpolio syndrome symptoms, no specific electrodiagnostic test for the syndrome is currently available.

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Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Electromyographic and morphological functional compensation in late poliomyelitis
Author: Einarsson G, Grimby G, Stålberg E
Affiliation: Department of Rehabilitation Medicine, Gothenburg University, Sweden
Journal: Muscle & Nerve
Citation: Muscle Nerve. 1990 Feb; 13(2):165-71
Publication Year and Month: 1990 02

Abstract: Patients with prior poliomyelitis may experience muscle function deterioration decades after onset of disease. The present study is aimed at describing electromyographic and morphometric evidence of muscular compensation and of on-going muscular instability. Ten subjects 42-62 years of age with onset of polio 25-52 years earlier were studied with macro EMG, single-fiber EMG (SFEMG), muscle strength measurement, and morphometrical analysis of muscle biopsies from the vastus lateralis muscle. SFEMG revealed increased fiber density (FD) and large macro-MUP potentials indicating pronounced reinnervation as compensation to loss of motor neurons. From electrophysiological data of motor unit size, morphometric measures of fiber size, and muscle strength data, the minimal degree of motor neuron loss was estimated to be greater than 70%.

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Category: Post-Polio Motor Unit

Title: Muscle Function, Muscle Structure, and Electrophysiology in a Dynamic Perspective in Late Polio
Author: Gunnar Grimby, MD, PhD, Erik Stålberg, MD.
Affiliation:
Journal: NEW - PUT DETAILS IN CITATION FIELD
Citation: Gunnar Grimby, MD, PhD, Erik Stålberg, MD., Muscle Function, Muscle Structure, and Electrophysiology in a Dynamic Perspective in Late Polio, Chapter 2, pp 15-24.
Publication Year and Month: 1995

Abstract: The muscular impairment in patients with a history of polio varies from none to severe. The relationship between the degree of initial involvement and the effect of various compensatory mechanisms determines the clinical picture, which changes dynamically. Early and late recovery after poliomyelitis depend on a number of factors. Clinical improvement that appears within a few weeks after the acute phase is probably due to recovery in the excitability of functional, but not degenerated, motor neurons. Degeneration of neurons, causing peripheral denervation, is compensated by collateral sprouting, i.e., by nerve twigs branching off from surviving motor units overlapping with the denervated ones. This is most likely the main factor explaining recovery within the first 6-12 months. Another late compensatory process is the increase in size of the muscle fibers. As a result of these processes, normal muscle strength and presumably normal muscle volume can be seen despite a calculated loss exceeding 50% of the number of motor neurons.

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Category: Post-Polio Motor Unit

Title: Repeater F-waves are signs of motor unit pathology in polio survivors
Author: Hachisuka A (1), Komori T, Abe T, Hachisuka K
Affiliation: (1) Department of Rehabilitation Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi, Kitakyushu, 807-8555, Japan
Journal: Muscle & Nerve
Citation: Muscle Nerve. 2015 May;51(5):680-5. doi: 10.1002/mus.24428
Publication Year and Month: 2015 05

Abstract: INTRODUCTION: The purpose of this study was to determine whether F-waves reveal electrophysiological features of anterior horn cells in polio survivors.

METHODS: Forty-three polio survivors and 20 healthy controls underwent motor nerve conduction studies of the median and tibial nerves bilaterally, including sampling of F-waves elicited by 100 stimuli and the determination of motor unit number estimation (MUNE).

RESULTS: A significant increase in abnormally stereotyped ("repeater") F-waves and a reduction of F-wave persistence were observed in both nerves in the polio group as compared with the control group. Repeater F-waves had a negative correlation with MUNE.

Conclusions: These trends in F-wave persistence and repeater F-waves after motor unit loss are characteristic findings in polio survivors. Repeater F-waves are a sign of motor unit pathology.

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Neurological manifestations of the post-polio syndrome
Author: Jubelt B, Cashman NR
Affiliation: Les Turner Amyotrophic Lateral Sclerosis Research Laboratory, Northwestern University Medical School, Chicago, Illinois
Journal: Critical Reviews in Neurobiology
Citation: Crit Rev Neurobiol. 1987;3(3):199-220
Publication Year and Month: 1987 03

Abstract: Patients with late effects of poliomyelitis, ie PPS, are being seen at an ever increasing frequency by general physicians, neurologists, and orthopedists. An appropriate time interval for the onset of late manifestations has elapsed since the major epidemics of poliomyelitis in the 1940s and 1950s. Post-polio neurological manifestations primarily include new weakness, atrophy, muscle pain, and fasciculations. Fortunately, the weakness is of a very slow, progressive nature. Abnormal laboratory studies include routine EMG, demonstrating chronic denervation; SFEMG, demonstrating increased fiber density, increased jitter, and blocking; and muscle biopsy most often revealing fiber-type grouping of chronic denervation and small isolated angular (or angulated) fibers and group atrophy in some series, both suggestive of active denervation. Unfortunately, both EMG and muscle biopsy studies suffer from a lack of specificity as they do not appear to distinguish asymptomatic from symptomatic (new weakness, PPMA) patients with prior poliomyelitis. Although the cause of PPMA is unknown, electrophysiological (SFEMG) and muscle biopsy studies suggest that the process involves a loss or dropout of axon terminals of reinnervated motor units. The axons terminal dropout could be due to dysfunction in the cell soma, the axon, or the terminals themselves. Whether motor neuron exhaustion, a persistent viral infection, or immune-mediated mechanisms play a role in the pathogenesis of the late weakness is unclear at present and will require further investigation. Treatment at this time is of a supportive nature. A major controversy involves the role of strengthening exercises in these patients since experimental animal studies suggest that excessive exercise of denervated muscles leads to increased weakness. Clearly, a better understanding of PPS and PPMA will allow more effective management of these patients’ problems and might also provide insight into other motor neuron and neuromuscular junction diseases.

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Category: Post-Polio Motor Unit

Title: Functional recovery – a major risk factor for the development of postpoliomyelitis muscular atrophy
Author: Klingman J, Chui H, Corgiat M, Perry J
Affiliation: Department of Neurology, University of Southern California School of Medicine, Los Angeles
Journal: Archives of Neurology
Citation: Arch Neurol. 1988 Jun;45(6):645-7
Publication Year and Month: 1988 06

Abstract: A retrospective study was undertaken to identify potential risk factors for the development of progressive postpoliomyelitis muscular atrophy (PPMA). Patients with PPMA (n = 57) were compared with patients with a history of poliomyelitis but without a history of progressive weakness (n = 49). Patients who later developed PPMA had histories of more widespread acute paralysis, but relatively greater functional recovery. They were less disabled, and reported higher recent activity levels. Seventy-nine percent of the total variance between the PPMA and control groups could be accounted for by recovery alone (ie, severity minus disability). Functional recovery is generally attributed to reinnervation of sarcomeres by collateral sprouting from surviving lower motor neurons. Since degree of recovery predicts the risk of developing PPMA, our findings suggest that enlarged motor units may carry an increased susceptibility for dysfunction and/or degeneration.

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Category: Post-Polio Motor Unit

Title: Correlation of Electrophysiology with Pathology, Pathogenesis, and Anticholinesterase Therapy in Post-Polio Syndrome
Author: Neil R. Cashman and Daria A. Trojan
Affiliation: Department of Neurology, Montreal Neurological Institute and Hospital, McGill University
Journal: Annals of the New York Academy of Sciences
Citation: Reprinted from The Post-Polio Syndrome: Advances in the Pathogenesis and Treatment
Volume 753 [pp 138-150] of the Annals of the New York Academy of Sciences
May 25, 1995
Publication Year and Month: 1995 05

Abstract:

Conclusions: A great deal of data has been generated on PPS, and a great deal more will be generated before we understand the pathophysiology of this common and disabling disorder. Perhaps now, to guide future work and direct therapeutic approaches, it is best to think of the symptoms of PPS as due to two lesions of the motor unit: a "progressive lesion" and a "fluctuating lesion." The progressive lesion gives rise to the symptom of slowly progressive weakness, and is due to the degeneration of terminal axons (and perhaps motor neurons) over the course of years. This lesion, best articulated by Wiechers and Hubble,[18] has been difficult to objectify because of its indolent nature. However, significant clinical weakening has indeed been quantified by several groups, including Munsat and colleagues,[7] and Sonies and Dalakas.[53] The best objective "proof" of the progressive lesion at present is the appearance of muscle fiber atrophy in biopsies, isolated and in groups, suggesting ongoing "permanent" denervation.[22] Diminution of motor unit size over time, as suggested by the macro-EMG studies of Lange et al.,[32] are also consistent with this hypothesis, albeit more controversial.

The other lesion of the PPS motor unit, hypothesized as a "fluctuating lesion," may be due to dysfunction of terminal axons, which gives rise to symptoms (muscle fatigability, generalized fatigue, and a component of weakness) that can change over the course of minutes to days. The underlying pathophysiology of these symptoms may be due to critical enlargement of motor units with limitations of distal components subserving axonal conduction and NMJ transmission, and/or the constant remodeling of the motor unit which appears to occur in virtually every individual after recovery from paralytic poliomyelitis. The best objective evidence for this ongoing lesion is provided by innumerable electrophysiologic studies demonstrating unstable motor unit action potentials and decrement on repetitive stimulation with conventional EMG, increased SFEMG jitter, and a host ofother studies.[54] In addition, the widespread expression of N-CAM in muscle biopsies of post-polio subjects (sometimes exceeding 10% of fibers)[22] strongly suggests that axono-myofiber interactions are distinctly unstable and/or immature. Clearly, agents that support the integrity or function of motor axonal sprouts may improve or delay patient symptoms in PPS.

Outcome of Research: Not applicable

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Category: Muscular Atrophy, Post-Polio Motor Unit

Title: An autopsy case of progressive generalized muscle atrophy over 14 years due to post-polio syndrome
Author: Oki R (1), Uchino A, Izumi Y, Ogawa H, Murayama S, Kaji R
Affiliation: (1) Department of Clinical Neuroscience, Institute of Health Bioscience, University of Tokushima Graduate School
Journal: Rinsho Shinkeigaku (Clinical Neurology)
Citation: Rinsho Shinkeigaku. 2015 Nov 30
Publication Year and Month: 2015 11

Abstract: We report the case of a 72-year-old man who had contracted acute paralytic poliomyelitis in his childhood. Thereafter, he had suffered from paresis involving the left lower limb, with no relapse or progression of the disease. He began noticing slowly progressive muscle weakness and atrophy in the upper and lower extremities in his 60s. At the age of 72, muscle weakness developed rapidly, and he demonstrated dyspnea on exertion and dysphagia. He died after about 14 years from the onset of muscle weakness symptoms. Autopsy findings demonstrated motoneuron loss and glial scars not only in the plaque-like lesions in the anterior horns, which were sequelae of old poliomyelitis, but also throughout the spine. No Bunina bodies, TDP-43, and ubiquitin inclusions were found. Post-polio syndrome is rarely fatal due to rapid progressive dyspnea and dysphagia. Thus, the pathological findings in the patient are considered to be related to the development of muscle weakness.

Conclusions:

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: A rat model of the post-polio motor unit
Author: Pachter BR, Eberstein A
Affiliation: Department of Rehabilitation Medicine, New York University Medical Center, NY 10016
Journal: Orthopedics
Citation: Orthopedics. 1991 Dec; 14(12):1367-73
Publication Year and Month: 1991 12

Abstract: We examined the long-term effects of muscle usage on a rat model of the post-polio motor unit. Isometric tensions, type I and type II muscle fiber areas, the incidence of collateral sprouting, and motor endplate morphology were examined following 1, 3, 6, and 9 months of partial denervation in rat plantaris muscle. Full morphologic and functional stability of the expanded motor units occurred at 6 months post-partial denervation. Fiber hypertrophy was observed, possibly the result of compensatory work hypertrophy due to muscle overuse. Following 9 months of partial denervation and muscle overuse, the twitch and tetanic tensions and type I and type II muscle fiber areas were significantly reduced as compared to sham controls; angulated myofibers and group atrophy also were seen. The percent collateral sprouting, the number of terminal branches per endplate, and the endplate area were all increased, possibly a compensatory response to a decreased synthesis of neurotrophic factor(s) and/or transmitter-related components. These aging-like changes seem to occur earlier in chronically stressed, overenlarged, and overworked motor units.

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Category: Post-Polio Motor Unit

Title: Polioencephalitis and the Brain Fatigue Generator Model of Post-Viral Fatigue Syndromes
Author: Richard L. Bruno, Ph.D., Nancy M. Frick, Lh.D., Susan Creange, M.A., Jerald R. Zimmerman, M.D., and Todd Lewis, Ph.D.


Affiliation: Post-Polio Rehabilitation and Research Service; Kessler Institute for Rehabilitation, Department of Physical Medicine and Rehabilitation; UMDNJ/New Jersey Medical School, Harvest Center; Hackensack, New Jersey
Journal:
Citation: Journal of Chronic Fatigue Syndrome, 1996; Department of Physical Medicine and Rehabilitation (in press)
Publication Year and Month: 1996

Abstract: Fatigue is the most commonly reported and most debilitating Post-Polio Sequelae (PPS) affecting millions of polio survivors world-wide. Post-polio fatigue is associated with: 1) subjective reports of difficulty with attention, cognition, word-finding and maintaining wakefulness; 2) clinically significant deficits on neuropsychological tests of information processing speed and attention; 3) gray and white matter hyperintensities in the reticular activating system on magnetic resonance imaging of the brain; 4) neuroendocrine evidence of impaired activation of the HPA axis. Many of these findings are identical to those documented following a variety of viral encephalitides, including acute poliovirus infection, lethargic encephalitis, Iceland Disease, myalgic encephalomyelitis, and, most recently, Chronic Fatigue Syndrome. The clinical, historic, neuropsychologic, neuroanatomic and physiologic parallels between poliovirus infection, post-polio fatigue and post-viral fatigue syndromes (PVFS) will be explored in an attempt to describe the pathophysiology of PVFS. The disinhibition of a putative Brain Fatigue Generator will be implicated as a cause of the subjective symptoms and objective signs that accompany PVFS. The results of a pilot placebo-controlled study of a dopamine 2 receptor agonist to treat post-polio fatigue will also be described.

Conclusions:

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Dynamic electromyography and muscle biopsy changes in a 4-year follow-up: study of patients with a history of polio
Author: Stålberg E, Grimby G
Affiliation: Department of Clinical Neurophysiology, University Hospital, Uppsala, Sweden
Journal: Muscle & Nerve
Citation: Muscle Nerve. 1995 Jul;18(7):699-707
Publication Year and Month: 1995 07

Abstract: Eighteen patients who had had polio 29-56 years prior to the first investigation were studied on two occasions, 4 years apart. Isokinetic and isometric strength measurements and Macro EMG were performed in 28 legs. Muscle biopsy specimens were obtained on both occasions from 11 legs. On average the muscle strength was 56% of control values at the first examination, and decreased by another 8% during the observation period. The muscle fiber area was increased compared to that of controls and did not change significantly. Macro EMG, comprising muscle fiber area and number of muscle fibers, and/or single fiber EMG showed clear signs of reinnervation in all legs. The motor units at the first examination were increased 11-fold, on average, compared with age-matched control values. During the observation period, reinnervation continued and the size of motor units increased by another 56% as a result of ongoing denervation, that is, loss of neurons. This compensation was particularly pronounced in patients with stable conditions. The parameters studied did not reveal any definite pattern predicting future development of new muscle weakness in individual subjects.

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Category: Post-Polio Motor Unit

Title: Acute and latent effect of poliomyelitis on the motor unit as revealed by electromyography
Author: Wiechers DO
Affiliation: Not stated
Journal: Orthopedics
Citation: Orthopedics. 1985 Jul; 8(7):870-2
Publication Year and Month: 1985 07

Abstract: When polio virus attacks the motor neuron it may be completely destroyed, damaged, or unaffected. Muscle fibers of a destroyed motor neuron are orphaned or reinnervated. Nearby functioning motor units will then send terminal axon sprouts to reinnervate the orphaned muscle fibers. If there are too many orphaned muscle fibers and not enough surviving motor units to reinnervate them, the orphaned muscle fibers will continue to fibrillate until they atrophy and die. The resultant effect of poliomyelitis upon the affected muscle is an overall loss of motor units with the remaining units innervating many more muscle fibers than they originally did. There appears to be a late effect of polio upon these larger reinnervated motor units. After approximately 20 to 30 years, impulse transmission to the muscle fibers of the large reinnervated motor unit begins to fail. These transmission difficulties increase with age and time from recovery. These late onset transmission abnormalities may be factors in patient complaints of fatigue and progressive weakness.

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There are currently 19 papers in this category.

Category: Post-Polio Motor Unit

Title: Polioencephalitis and the Brain Fatigue Generator Model of Post-Viral Fatigue Syndromes
Author: Richard L. Bruno, Ph.D., Nancy M. Frick, Lh.D., Susan Creange, M.A., Jerald R. Zimmerman, M.D., and Todd Lewis, Ph.D.


Affiliation: Post-Polio Rehabilitation and Research Service; Kessler Institute for Rehabilitation, Department of Physical Medicine and Rehabilitation; UMDNJ/New Jersey Medical School, Harvest Center; Hackensack, New Jersey
Journal:
Citation: Journal of Chronic Fatigue Syndrome, 1996; Department of Physical Medicine and Rehabilitation (in press)
Publication Year and Month: 1996

Abstract: Fatigue is the most commonly reported and most debilitating Post-Polio Sequelae (PPS) affecting millions of polio survivors world-wide. Post-polio fatigue is associated with: 1) subjective reports of difficulty with attention, cognition, word-finding and maintaining wakefulness; 2) clinically significant deficits on neuropsychological tests of information processing speed and attention; 3) gray and white matter hyperintensities in the reticular activating system on magnetic resonance imaging of the brain; 4) neuroendocrine evidence of impaired activation of the HPA axis. Many of these findings are identical to those documented following a variety of viral encephalitides, including acute poliovirus infection, lethargic encephalitis, Iceland Disease, myalgic encephalomyelitis, and, most recently, Chronic Fatigue Syndrome. The clinical, historic, neuropsychologic, neuroanatomic and physiologic parallels between poliovirus infection, post-polio fatigue and post-viral fatigue syndromes (PVFS) will be explored in an attempt to describe the pathophysiology of PVFS. The disinhibition of a putative Brain Fatigue Generator will be implicated as a cause of the subjective symptoms and objective signs that accompany PVFS. The results of a pilot placebo-controlled study of a dopamine 2 receptor agonist to treat post-polio fatigue will also be described.

Conclusions:

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Stimulation frequency-dependent neuromuscular junction transmission defects in patients with prior poliomyelitis
Author: Daria A. Trojan, Daniel Gendron and Neil R. Cashman
Affiliation: Department of Neurology, McGill University, Montreal Neurological Institute and Hospital
Journal:
Citation: Journal of the Neurological Sciences, 118 (1993) 150-157
Publication Year and Month: 1993 03

Abstract: Generalized fatigue and muscle fatiguability are major symptoms of post-poliomyelitis syndrome (PPS), and may be due to neuromuscular junction transmission defects, as suggested by increased jitter on single fiber electromyography (SFEMG). To determine the etiology of this defect, we studied jitter at low (1, 5 Hz) and high (10, 15, 20 Hz) frequency stimulation with stimulation SFEMG in 17 post-polio patients with muscle fatiguability, and in 9 normal controls. In 5 of 17 PPS patients and in 1 of 9 controls, jitter was significantly higher (unpaired t-test, P < 0.05) at high frequency stimulation (HFS). In the remaining PPS patients and controls there was no significant difference in jitter at high and low stimulation frequencies. PPS patients with increased jitter at HFS had a significantly longer time interval since acute polio (mean 48.5 years) than PPS patients without increased jitter at HFS (mean 40 years; P < 0.05), but were not distinguished by other historical or clinical criteria. We conclude that the neuromuscular junction defect in post-polio patients is similar to that observed in amyotrophic lateral sclerosis, and is probably due to ineffective conduction along immature nerve sprouts and exhaustion of acetylcholine stores. The appearance of an increase in jitter with HFS in post-polio patients may be dependent upon time after acute polio.

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Category: Post-Polio Motor Unit

Title: Correlation of Electrophysiology with Pathology, Pathogenesis, and Anticholinesterase Therapy in Post-Polio Syndrome
Author: Neil R. Cashman and Daria A. Trojan
Affiliation: Department of Neurology, Montreal Neurological Institute and Hospital, McGill University
Journal: Annals of the New York Academy of Sciences
Citation: Reprinted from The Post-Polio Syndrome: Advances in the Pathogenesis and Treatment
Volume 753 [pp 138-150] of the Annals of the New York Academy of Sciences
May 25, 1995
Publication Year and Month: 1995 05

Abstract:

Conclusions: A great deal of data has been generated on PPS, and a great deal more will be generated before we understand the pathophysiology of this common and disabling disorder. Perhaps now, to guide future work and direct therapeutic approaches, it is best to think of the symptoms of PPS as due to two lesions of the motor unit: a "progressive lesion" and a "fluctuating lesion." The progressive lesion gives rise to the symptom of slowly progressive weakness, and is due to the degeneration of terminal axons (and perhaps motor neurons) over the course of years. This lesion, best articulated by Wiechers and Hubble,[18] has been difficult to objectify because of its indolent nature. However, significant clinical weakening has indeed been quantified by several groups, including Munsat and colleagues,[7] and Sonies and Dalakas.[53] The best objective "proof" of the progressive lesion at present is the appearance of muscle fiber atrophy in biopsies, isolated and in groups, suggesting ongoing "permanent" denervation.[22] Diminution of motor unit size over time, as suggested by the macro-EMG studies of Lange et al.,[32] are also consistent with this hypothesis, albeit more controversial.

The other lesion of the PPS motor unit, hypothesized as a "fluctuating lesion," may be due to dysfunction of terminal axons, which gives rise to symptoms (muscle fatigability, generalized fatigue, and a component of weakness) that can change over the course of minutes to days. The underlying pathophysiology of these symptoms may be due to critical enlargement of motor units with limitations of distal components subserving axonal conduction and NMJ transmission, and/or the constant remodeling of the motor unit which appears to occur in virtually every individual after recovery from paralytic poliomyelitis. The best objective evidence for this ongoing lesion is provided by innumerable electrophysiologic studies demonstrating unstable motor unit action potentials and decrement on repetitive stimulation with conventional EMG, increased SFEMG jitter, and a host ofother studies.[54] In addition, the widespread expression of N-CAM in muscle biopsies of post-polio subjects (sometimes exceeding 10% of fibers)[22] strongly suggests that axono-myofiber interactions are distinctly unstable and/or immature. Clearly, agents that support the integrity or function of motor axonal sprouts may improve or delay patient symptoms in PPS.

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Electrodiagnostic Findings in 108 Consecutive Patients Referred to a Post-Polio Clinic – The Value of Routine Electrodiagnostic Studies
Author: Anne C. Gawne, Bao T. Pham, and Lauro S. Halstead

Affiliation:
Journal: Annals of the New York Academy of Sciences
Citation: The Post-Polio Syndrome: Advances in the Pathogenesis and Treatment Volume 753 pp 383-385 of the Annals of the New York Academy of Sciences May 25, 1995.
Publication Year and Month: 1995 05

Abstract: Many patients with a history of polio develop new symptoms including weakness, pain, fatigue, and changes in function, or post-polio syndrome (PPS).[1] Before a diagnosis of PPS is made, other diagnoses must first be ruled out. Assessment must be done in a comprehensive and coordinated manner.[2] Therefore, as part of our routine evaluation, we do an electromyogram/nerve conduction study (EMG/NCS) on every patient. During examinations on our clinic patients we began to notice (1) electrodiagnostic evidence of polio in limbs not previously felt to be involved; (2) a normal EMG, or evidence of another disease; and (3) EMG evidence consistent with additional neurological lesions, including compression neuropathies, peripheral neuropathies, and radiculopathies. A prospective study using a routine, standardized four-extremity electrodiagnostic protocol was done to quantify the frequency of these occurrences.

Conclusions: Our findings strongly support the value of a standardized four-extremity EMG/NCS as an adjuvant to a comprehensive history and physical examination. It helps to differentiate between old polio and other neurological diagnoses. There is a high prevalence of subclinical polio, which is important to know about in order to give proper recommendations regarding rest and activity. Given the frequency of risk factors for development of potentially treatable neurological lesions like CTS, early detection is valuable. We believe routine electrodiagnostic testing is essential for proper evaluation and management of the post-polio patient.

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Category: Post-Polio Motor Unit

Title: Functional recovery – a major risk factor for the development of postpoliomyelitis muscular atrophy
Author: Klingman J, Chui H, Corgiat M, Perry J
Affiliation: Department of Neurology, University of Southern California School of Medicine, Los Angeles
Journal: Archives of Neurology
Citation: Arch Neurol. 1988 Jun;45(6):645-7
Publication Year and Month: 1988 06

Abstract: A retrospective study was undertaken to identify potential risk factors for the development of progressive postpoliomyelitis muscular atrophy (PPMA). Patients with PPMA (n = 57) were compared with patients with a history of poliomyelitis but without a history of progressive weakness (n = 49). Patients who later developed PPMA had histories of more widespread acute paralysis, but relatively greater functional recovery. They were less disabled, and reported higher recent activity levels. Seventy-nine percent of the total variance between the PPMA and control groups could be accounted for by recovery alone (ie, severity minus disability). Functional recovery is generally attributed to reinnervation of sarcomeres by collateral sprouting from surviving lower motor neurons. Since degree of recovery predicts the risk of developing PPMA, our findings suggest that enlarged motor units may carry an increased susceptibility for dysfunction and/or degeneration.

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Category: Post-Polio Motor Unit

Title: Late effects of polio: critical review of the literature on neuromuscular function
Author: Agre JC, Rodríquez AA, Tafel JA
Affiliation: University of Wisconsin - Madison Medical School
Journal: Archives of Physical Medicine and Rehabilitation
Citation: Arch Phys Med Rehabil. 1991 Oct; 72(11):923-31
Publication Year and Month: 1991 10

Abstract: Many individuals who have had poliomyelitis are now complaining of several new problems attributed to their former illness including muscle atrophy; fatigue; progressive weakness; and muscle, back, and joint pain. This paper critically examines the literature regarding the neuromuscular effects of poliomyelitis. Weakness resulting from poliomyelitis was due to destruction of anterior horn cells. After the illness, muscle strength was partially recovered as a result of several physiologic adaptive mechanisms including terminal sprouting and reinnervation, myofiber hypertrophy, and, possibly, myofiber type transformation. Several pathophysiologic and functional etiologies have been proposed for late neuromuscular deterioration, but none has been proven. In fact, to date, there is no objective evidence documenting progressive loss of strength in polio survivors. Studies attempting to differentiate polio survivors with and without symptoms of deterioration have resulted in conflicting results; however, it appears reasonable to conclude that symptomatic postpolio subjects had a more severe illness with greater loss of neuromuscular function. Exercise may be helpful for many postpolio patients, but the prescription must be tailored to the individual to avoid problems of overuse or excessive fatigue.

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Category: Post-Polio Motor Unit

Title: Loss of motor unit size and quadriceps strength over 10 years in post-polio syndrome
Author: Bickerstaffe A (1), van Dijk JP (2), Beelen A (3), Zwarts MJ (4), Nollet F (5)
Affiliation: (1) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]; (2) Radboud University Nijmegen Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Department of Neurology/Clinical Neurophysiology, Postbus 910, 6500 HB Nijmegen, The Netherlands; Epilepsy Centre Kempenhaeghe, Postbus 61, 5590 AB Heeze, The Netherlands. Electronic address: [email protected]; (3) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]; (4) Epilepsy Centre Kempenhaeghe, Postbus 61, 5590 AB Heeze, The Netherlands. Electronic address: [email protected]; (5) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]
Journal: Clinical Neurophysiology
Citation: Clin Neurophysiol. 2014 Jun;125(6):1255-60. doi: 10.1016/j.clinph.2013.11.003
Publication Year and Month: 2014 06

Abstract: OBJECTIVE: To investigate whether strength decline in post-polio syndrome (PPS) results from excessive distal axonal degeneration of enlarged motor units.

METHODS: We assessed changes over 10 years in isometric quadriceps strength, mean motor unit action potential (MUAP) size, root mean squared (RMS) amplitude, and level of interference (LOI) in 47 patients with PPS and 12 healthy controls, using high density surface EMG. At baseline, all patients had symptomatic quadriceps dysfunction, evidenced by transmission defects on single-fibre EMG.

RESULTS: MU size and strength declined significantly by 20% and 15%, respectively in patients with PPS. Those with the largest initial MU sizes exhibited the greatest losses of mean MU size (27%) and proportional decreases in quadriceps strength (23%). Initial strength, change in LOI and change in RMS amplitude together explained 35% of the variability in strength changes in patients. MU size of controls did not change, although they lost 29% strength.

SIGNIFICANCE: This long term follow-up study provides evidence that size diminution of enlarged MUs combined with a reduced number of active MUs contributes to the gradual strength decline in PPS.

Conclusions: MU size and strength declined concomitantly in a homogeneous cohort of patients with PPS and quadriceps dysfunction.

Outcome of Research: Effective

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Category: Post-Polio Motor Unit

Title: Neurological manifestations of the post-polio syndrome
Author: Jubelt B, Cashman NR
Affiliation: Les Turner Amyotrophic Lateral Sclerosis Research Laboratory, Northwestern University Medical School, Chicago, Illinois
Journal: Critical Reviews in Neurobiology
Citation: Crit Rev Neurobiol. 1987;3(3):199-220
Publication Year and Month: 1987 03

Abstract: Patients with late effects of poliomyelitis, ie PPS, are being seen at an ever increasing frequency by general physicians, neurologists, and orthopedists. An appropriate time interval for the onset of late manifestations has elapsed since the major epidemics of poliomyelitis in the 1940s and 1950s. Post-polio neurological manifestations primarily include new weakness, atrophy, muscle pain, and fasciculations. Fortunately, the weakness is of a very slow, progressive nature. Abnormal laboratory studies include routine EMG, demonstrating chronic denervation; SFEMG, demonstrating increased fiber density, increased jitter, and blocking; and muscle biopsy most often revealing fiber-type grouping of chronic denervation and small isolated angular (or angulated) fibers and group atrophy in some series, both suggestive of active denervation. Unfortunately, both EMG and muscle biopsy studies suffer from a lack of specificity as they do not appear to distinguish asymptomatic from symptomatic (new weakness, PPMA) patients with prior poliomyelitis. Although the cause of PPMA is unknown, electrophysiological (SFEMG) and muscle biopsy studies suggest that the process involves a loss or dropout of axon terminals of reinnervated motor units. The axons terminal dropout could be due to dysfunction in the cell soma, the axon, or the terminals themselves. Whether motor neuron exhaustion, a persistent viral infection, or immune-mediated mechanisms play a role in the pathogenesis of the late weakness is unclear at present and will require further investigation. Treatment at this time is of a supportive nature. A major controversy involves the role of strengthening exercises in these patients since experimental animal studies suggest that excessive exercise of denervated muscles leads to increased weakness. Clearly, a better understanding of PPS and PPMA will allow more effective management of these patients’ problems and might also provide insight into other motor neuron and neuromuscular junction diseases.

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Category: Post-Polio Motor Unit

Title: Electromyographic and morphological functional compensation in late poliomyelitis
Author: Einarsson G, Grimby G, Stålberg E
Affiliation: Department of Rehabilitation Medicine, Gothenburg University, Sweden
Journal: Muscle & Nerve
Citation: Muscle Nerve. 1990 Feb; 13(2):165-71
Publication Year and Month: 1990 02

Abstract: Patients with prior poliomyelitis may experience muscle function deterioration decades after onset of disease. The present study is aimed at describing electromyographic and morphometric evidence of muscular compensation and of on-going muscular instability. Ten subjects 42-62 years of age with onset of polio 25-52 years earlier were studied with macro EMG, single-fiber EMG (SFEMG), muscle strength measurement, and morphometrical analysis of muscle biopsies from the vastus lateralis muscle. SFEMG revealed increased fiber density (FD) and large macro-MUP potentials indicating pronounced reinnervation as compensation to loss of motor neurons. From electrophysiological data of motor unit size, morphometric measures of fiber size, and muscle strength data, the minimal degree of motor neuron loss was estimated to be greater than 70%.

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Category: Post-Polio Motor Unit

Title: Dynamic electromyography and muscle biopsy changes in a 4-year follow-up: study of patients with a history of polio
Author: Stålberg E, Grimby G
Affiliation: Department of Clinical Neurophysiology, University Hospital, Uppsala, Sweden
Journal: Muscle & Nerve
Citation: Muscle Nerve. 1995 Jul;18(7):699-707
Publication Year and Month: 1995 07

Abstract: Eighteen patients who had had polio 29-56 years prior to the first investigation were studied on two occasions, 4 years apart. Isokinetic and isometric strength measurements and Macro EMG were performed in 28 legs. Muscle biopsy specimens were obtained on both occasions from 11 legs. On average the muscle strength was 56% of control values at the first examination, and decreased by another 8% during the observation period. The muscle fiber area was increased compared to that of controls and did not change significantly. Macro EMG, comprising muscle fiber area and number of muscle fibers, and/or single fiber EMG showed clear signs of reinnervation in all legs. The motor units at the first examination were increased 11-fold, on average, compared with age-matched control values. During the observation period, reinnervation continued and the size of motor units increased by another 56% as a result of ongoing denervation, that is, loss of neurons. This compensation was particularly pronounced in patients with stable conditions. The parameters studied did not reveal any definite pattern predicting future development of new muscle weakness in individual subjects.

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Category: Post-Polio Motor Unit

Title: Repeater F-waves are signs of motor unit pathology in polio survivors
Author: Hachisuka A (1), Komori T, Abe T, Hachisuka K
Affiliation: (1) Department of Rehabilitation Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi, Kitakyushu, 807-8555, Japan
Journal: Muscle & Nerve
Citation: Muscle Nerve. 2015 May;51(5):680-5. doi: 10.1002/mus.24428
Publication Year and Month: 2015 05

Abstract: INTRODUCTION: The purpose of this study was to determine whether F-waves reveal electrophysiological features of anterior horn cells in polio survivors.

METHODS: Forty-three polio survivors and 20 healthy controls underwent motor nerve conduction studies of the median and tibial nerves bilaterally, including sampling of F-waves elicited by 100 stimuli and the determination of motor unit number estimation (MUNE).

RESULTS: A significant increase in abnormally stereotyped ("repeater") F-waves and a reduction of F-wave persistence were observed in both nerves in the polio group as compared with the control group. Repeater F-waves had a negative correlation with MUNE.

Conclusions: These trends in F-wave persistence and repeater F-waves after motor unit loss are characteristic findings in polio survivors. Repeater F-waves are a sign of motor unit pathology.

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Muscle Function, Muscle Structure, and Electrophysiology in a Dynamic Perspective in Late Polio
Author: Gunnar Grimby, MD, PhD, Erik Stålberg, MD.
Affiliation:
Journal: NEW - PUT DETAILS IN CITATION FIELD
Citation: Gunnar Grimby, MD, PhD, Erik Stålberg, MD., Muscle Function, Muscle Structure, and Electrophysiology in a Dynamic Perspective in Late Polio, Chapter 2, pp 15-24.
Publication Year and Month: 1995

Abstract: The muscular impairment in patients with a history of polio varies from none to severe. The relationship between the degree of initial involvement and the effect of various compensatory mechanisms determines the clinical picture, which changes dynamically. Early and late recovery after poliomyelitis depend on a number of factors. Clinical improvement that appears within a few weeks after the acute phase is probably due to recovery in the excitability of functional, but not degenerated, motor neurons. Degeneration of neurons, causing peripheral denervation, is compensated by collateral sprouting, i.e., by nerve twigs branching off from surviving motor units overlapping with the denervated ones. This is most likely the main factor explaining recovery within the first 6-12 months. Another late compensatory process is the increase in size of the muscle fibers. As a result of these processes, normal muscle strength and presumably normal muscle volume can be seen despite a calculated loss exceeding 50% of the number of motor neurons.

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Category: Post-Polio Motor Unit

Title: Vasomotor abnormalities as post-polio sequelae: functional and clinical implications
Author: Bruno RL, Johnson JC, Berman WS
Affiliation: Not stated
Journal: Orthopedics
Citation: Orthopedics. 1985 Jul; 8(7):865-9
Publication Year and Month: 1985 07

Abstract: Persons who had poliomyelitis report cold and discolored extremities and decreased muscle strength when exposed to mildly cool ambient temperatures. Bilateral digital cutaneous blood flow, skin temperature and median nerve latencies and amplitudes were measured at 30 degrees C, 25 degrees C and 20 degrees C in five post-polio subjects and age-matched controls. Cutaneous blood flow was lowest on the more affected side in the post-polio subjects but vasoconstriction with decreasing Ta was equal bilaterally in both groups. With decreasing Ta, median motor nerve latencies became clinically abnormal and “giant” sensory nerve potential amplitudes were seen in a majority of the post-polio subjects. It is concluded that an impairment of sympathetic vasoconstrictor outflow in post-polios allows passive dilatation and engorgement of the cutaneous venous capacitance beds. This promotes uncontrolled heat loss and causes cooling of nerve and muscle that is responsible for the impairment of muscle functioning and the abnormal electrophysiological findings.

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Category: Post-Polio Motor Unit

Title: Acute and latent effect of poliomyelitis on the motor unit as revealed by electromyography
Author: Wiechers DO
Affiliation: Not stated
Journal: Orthopedics
Citation: Orthopedics. 1985 Jul; 8(7):870-2
Publication Year and Month: 1985 07

Abstract: When polio virus attacks the motor neuron it may be completely destroyed, damaged, or unaffected. Muscle fibers of a destroyed motor neuron are orphaned or reinnervated. Nearby functioning motor units will then send terminal axon sprouts to reinnervate the orphaned muscle fibers. If there are too many orphaned muscle fibers and not enough surviving motor units to reinnervate them, the orphaned muscle fibers will continue to fibrillate until they atrophy and die. The resultant effect of poliomyelitis upon the affected muscle is an overall loss of motor units with the remaining units innervating many more muscle fibers than they originally did. There appears to be a late effect of polio upon these larger reinnervated motor units. After approximately 20 to 30 years, impulse transmission to the muscle fibers of the large reinnervated motor unit begins to fail. These transmission difficulties increase with age and time from recovery. These late onset transmission abnormalities may be factors in patient complaints of fatigue and progressive weakness.

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Category: Post-Polio Motor Unit

Title: A rat model of the post-polio motor unit
Author: Pachter BR, Eberstein A
Affiliation: Department of Rehabilitation Medicine, New York University Medical Center, NY 10016
Journal: Orthopedics
Citation: Orthopedics. 1991 Dec; 14(12):1367-73
Publication Year and Month: 1991 12

Abstract: We examined the long-term effects of muscle usage on a rat model of the post-polio motor unit. Isometric tensions, type I and type II muscle fiber areas, the incidence of collateral sprouting, and motor endplate morphology were examined following 1, 3, 6, and 9 months of partial denervation in rat plantaris muscle. Full morphologic and functional stability of the expanded motor units occurred at 6 months post-partial denervation. Fiber hypertrophy was observed, possibly the result of compensatory work hypertrophy due to muscle overuse. Following 9 months of partial denervation and muscle overuse, the twitch and tetanic tensions and type I and type II muscle fiber areas were significantly reduced as compared to sham controls; angulated myofibers and group atrophy also were seen. The percent collateral sprouting, the number of terminal branches per endplate, and the endplate area were all increased, possibly a compensatory response to a decreased synthesis of neurotrophic factor(s) and/or transmitter-related components. These aging-like changes seem to occur earlier in chronically stressed, overenlarged, and overworked motor units.

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Category: Post-Polio Motor Unit

Title: Electrophysiology and Electrodiagnosis of the Post-Polio Motor Unit
Author: Daria A. Trojan, MD, Daniel Gendron, MD, Neil R. Cashman, MD
Affiliation:
Journal: Orthopedics
Citation: Orthopedics December 1991 Vol 14 No 12 1353-1361
Publication Year and Month: 1991 12

Abstract: Post-poliomyelitis syndrome refers to new symptoms that may occur years after recovery from poliomyelitis. The most common of these symptoms are new weakness, fatigue, and pain. This article describes electrodiagnostic studies -- conventional electromyography (EMG), single fiber electromyography (SFEMG), and macroelectromyography (macro-EMG) -- that have provided information on the post-polio motor unit and on the possible etiology of some post-polio syndrome symptoms. Muscular fatigue, and indirectly, general fatigue, may be due to neuromuscular junction transmission defects in some post-polio individuals, as suggested by reduction of the compound motor action potentials on repetitive stimulation, and increased jitter and blocking on SFEMG. Progressive weakness and atrophy in post-polio syndrome is probably due to a distal degeneration of post-polio motor units with resultant irreversible muscle fiber denervation. Electrodiagnostic evidence of ongoing denervation includes fibrillation and fasciculation potentials on conventional EMG, increased jitter and blocking on SFEMG, and smaller macro-EMG amplitudes in newly weakened postpolio muscles. However, even though electrodiagnostic studies have provided insight into the possible causes of some postpolio syndrome symptoms, no specific electrodiagnostic test for the syndrome is currently available.

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Category: Muscular Atrophy, Post-Polio Motor Unit

Title: An autopsy case of progressive generalized muscle atrophy over 14 years due to post-polio syndrome
Author: Oki R (1), Uchino A, Izumi Y, Ogawa H, Murayama S, Kaji R
Affiliation: (1) Department of Clinical Neuroscience, Institute of Health Bioscience, University of Tokushima Graduate School
Journal: Rinsho Shinkeigaku (Clinical Neurology)
Citation: Rinsho Shinkeigaku. 2015 Nov 30
Publication Year and Month: 2015 11

Abstract: We report the case of a 72-year-old man who had contracted acute paralytic poliomyelitis in his childhood. Thereafter, he had suffered from paresis involving the left lower limb, with no relapse or progression of the disease. He began noticing slowly progressive muscle weakness and atrophy in the upper and lower extremities in his 60s. At the age of 72, muscle weakness developed rapidly, and he demonstrated dyspnea on exertion and dysphagia. He died after about 14 years from the onset of muscle weakness symptoms. Autopsy findings demonstrated motoneuron loss and glial scars not only in the plaque-like lesions in the anterior horns, which were sequelae of old poliomyelitis, but also throughout the spine. No Bunina bodies, TDP-43, and ubiquitin inclusions were found. Post-polio syndrome is rarely fatal due to rapid progressive dyspnea and dysphagia. Thus, the pathological findings in the patient are considered to be related to the development of muscle weakness.

Conclusions:

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Late denervation in patients with antecedent paralytic poliomyelitis
Author: Cashman NR, Maselli R, Wollmann RL, Roos R, Simon R, Antel JP
Affiliation: Not stated
Journal: The New England Journal of Medicine
Citation: N Engl J Med. 1987 Jul 2; 317(1):7-12
Publication Year and Month: 1987 07

Abstract: The development of new weakness, fatigue, and pain decades after acute paralytic poliomyelitis is a recognized syndrome. We conducted a controlled study of this syndrome by analyzing clinical, electromyographic, and muscle-biopsy features in 18 patients with a history of poliomyelitis--13 reporting 1 to 20 years of new weakness and 5 without new symptoms. The patients with new weakness also reported new muscle atrophy (9 of 13) and fatigue (10 of 13), symptoms not reported by the controls. The age at the time of acute poliomyelitis, severity of poliomyelitis, residual disability, number of years since acute poliomyelitis, and age at the time of study were comparable in the weakening and control groups. Evidence of remote denervation consistent with antecedent poliomyelitis was demonstrated in all patients by electromyography or muscle biopsy or both. In addition, active denervation (as evidenced by spontaneous activity on conventional electromyography, increased jitter on single-fiber electromyography, or atrophic myofibers) was found in 12 patients in the weakening group and in all 5 controls. Immunohistochemical detection of myofibers expressing the neural-cell adhesion molecule corroborated ongoing denervation in both patient groups. When muscle data from both groups were pooled, correlations were observed between the extent of past reinnervation and the degree of ongoing motor-unit instability. We conclude that the extensive reinnervation of denervated muscle that occurs in paralytic poliomyelitis may be followed by late denervation of the previously reinnervated muscle fibers. Electromyographic and muscle-biopsy evidence of ongoing denervation does not distinguish between stable patients with prior paralytic poliomyelitis and those with new weakness.

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Category: Post-Polio Motor Unit

Title: A long-term follow-up study of patients with post-poliomyelitis neuromuscular symptoms
Author: Dalakas MC, Elder G, Hallett M, Ravits J, Baker M, Papadopoulos N, Albrecht P, Sever J
Affiliation: Not stated
Journal: The New England Journal of Medicine
Citation: N Engl J Med. 1986 Apr 10; 314(15):959-63
Publication Year and Month: 1986 04

Abstract: A “post-polio” syndrome characterized by new neuromuscular symptoms, including muscle weakness, may develop years after recovery from acute paralytic poliomyelitis. We studied 27 patients (mean age, 50.6 years) in whom new muscle weakness developed a mean of 28.8 years after recovery from acute polio. We reevaluated these patients during a mean follow-up period of 8.2 years (range, 4.5 to 20) after they were originally studied at the National Institutes of Health. The total mean follow-up period after the onset of new weakness was 12.2 years (range, 6 to 29). The patients were assessed with quantitative muscle testing, muscle biopsy, electromyography, and virologic and immunologic examination of the cerebrospinal fluid. Muscle strength had declined in all patients. The rate of decline averaged 1 percent per year. The decrease was irregular, with subjective plateau periods that ranged from 1 to 10 years. None of the patients had amyotrophic lateral sclerosis. Oligoclonal bands (IgG) were found in the cerebrospinal fluid of 7 of 13 patients studied, but no specific elevation of antibodies to poliovirus was observed in the cerebrospinal fluid. The newly affected muscles that were evaluated longitudinally with follow-up muscle biopsies and electromyography showed signs of chronic and new denervation. Groups of atrophic muscle fibers (group atrophy) and "neurogenic jitter" were not present. New post-polio muscle weakness is not a life-threatening form of motor-neuron deterioration. It appears that this weakness is not due to a loss of whole motor neurons, as in amyotrophic lateral sclerosis, but that it is due to a dysfunction of the surviving motor neurons that causes a slow disintegration of the terminals of individual nerve axons.

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There are currently 19 papers in this category.

Category: Muscular Atrophy, Post-Polio Motor Unit

Title: An autopsy case of progressive generalized muscle atrophy over 14 years due to post-polio syndrome
Author: Oki R (1), Uchino A, Izumi Y, Ogawa H, Murayama S, Kaji R
Affiliation: (1) Department of Clinical Neuroscience, Institute of Health Bioscience, University of Tokushima Graduate School
Journal: Rinsho Shinkeigaku (Clinical Neurology)
Citation: Rinsho Shinkeigaku. 2015 Nov 30
Publication Year and Month: 2015 11

Abstract: We report the case of a 72-year-old man who had contracted acute paralytic poliomyelitis in his childhood. Thereafter, he had suffered from paresis involving the left lower limb, with no relapse or progression of the disease. He began noticing slowly progressive muscle weakness and atrophy in the upper and lower extremities in his 60s. At the age of 72, muscle weakness developed rapidly, and he demonstrated dyspnea on exertion and dysphagia. He died after about 14 years from the onset of muscle weakness symptoms. Autopsy findings demonstrated motoneuron loss and glial scars not only in the plaque-like lesions in the anterior horns, which were sequelae of old poliomyelitis, but also throughout the spine. No Bunina bodies, TDP-43, and ubiquitin inclusions were found. Post-polio syndrome is rarely fatal due to rapid progressive dyspnea and dysphagia. Thus, the pathological findings in the patient are considered to be related to the development of muscle weakness.

Conclusions:

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Repeater F-waves are signs of motor unit pathology in polio survivors
Author: Hachisuka A (1), Komori T, Abe T, Hachisuka K
Affiliation: (1) Department of Rehabilitation Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi, Kitakyushu, 807-8555, Japan
Journal: Muscle & Nerve
Citation: Muscle Nerve. 2015 May;51(5):680-5. doi: 10.1002/mus.24428
Publication Year and Month: 2015 05

Abstract: INTRODUCTION: The purpose of this study was to determine whether F-waves reveal electrophysiological features of anterior horn cells in polio survivors.

METHODS: Forty-three polio survivors and 20 healthy controls underwent motor nerve conduction studies of the median and tibial nerves bilaterally, including sampling of F-waves elicited by 100 stimuli and the determination of motor unit number estimation (MUNE).

RESULTS: A significant increase in abnormally stereotyped ("repeater") F-waves and a reduction of F-wave persistence were observed in both nerves in the polio group as compared with the control group. Repeater F-waves had a negative correlation with MUNE.

Conclusions: These trends in F-wave persistence and repeater F-waves after motor unit loss are characteristic findings in polio survivors. Repeater F-waves are a sign of motor unit pathology.

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Loss of motor unit size and quadriceps strength over 10 years in post-polio syndrome
Author: Bickerstaffe A (1), van Dijk JP (2), Beelen A (3), Zwarts MJ (4), Nollet F (5)
Affiliation: (1) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]; (2) Radboud University Nijmegen Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Department of Neurology/Clinical Neurophysiology, Postbus 910, 6500 HB Nijmegen, The Netherlands; Epilepsy Centre Kempenhaeghe, Postbus 61, 5590 AB Heeze, The Netherlands. Electronic address: [email protected]; (3) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]; (4) Epilepsy Centre Kempenhaeghe, Postbus 61, 5590 AB Heeze, The Netherlands. Electronic address: [email protected]; (5) Department of Rehabilitation, Academic Medical Center (AMC), Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: [email protected]
Journal: Clinical Neurophysiology
Citation: Clin Neurophysiol. 2014 Jun;125(6):1255-60. doi: 10.1016/j.clinph.2013.11.003
Publication Year and Month: 2014 06

Abstract: OBJECTIVE: To investigate whether strength decline in post-polio syndrome (PPS) results from excessive distal axonal degeneration of enlarged motor units.

METHODS: We assessed changes over 10 years in isometric quadriceps strength, mean motor unit action potential (MUAP) size, root mean squared (RMS) amplitude, and level of interference (LOI) in 47 patients with PPS and 12 healthy controls, using high density surface EMG. At baseline, all patients had symptomatic quadriceps dysfunction, evidenced by transmission defects on single-fibre EMG.

RESULTS: MU size and strength declined significantly by 20% and 15%, respectively in patients with PPS. Those with the largest initial MU sizes exhibited the greatest losses of mean MU size (27%) and proportional decreases in quadriceps strength (23%). Initial strength, change in LOI and change in RMS amplitude together explained 35% of the variability in strength changes in patients. MU size of controls did not change, although they lost 29% strength.

SIGNIFICANCE: This long term follow-up study provides evidence that size diminution of enlarged MUs combined with a reduced number of active MUs contributes to the gradual strength decline in PPS.

Conclusions: MU size and strength declined concomitantly in a homogeneous cohort of patients with PPS and quadriceps dysfunction.

Outcome of Research: Effective

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Category: Post-Polio Motor Unit

Title: Polioencephalitis and the Brain Fatigue Generator Model of Post-Viral Fatigue Syndromes
Author: Richard L. Bruno, Ph.D., Nancy M. Frick, Lh.D., Susan Creange, M.A., Jerald R. Zimmerman, M.D., and Todd Lewis, Ph.D.


Affiliation: Post-Polio Rehabilitation and Research Service; Kessler Institute for Rehabilitation, Department of Physical Medicine and Rehabilitation; UMDNJ/New Jersey Medical School, Harvest Center; Hackensack, New Jersey
Journal:
Citation: Journal of Chronic Fatigue Syndrome, 1996; Department of Physical Medicine and Rehabilitation (in press)
Publication Year and Month: 1996

Abstract: Fatigue is the most commonly reported and most debilitating Post-Polio Sequelae (PPS) affecting millions of polio survivors world-wide. Post-polio fatigue is associated with: 1) subjective reports of difficulty with attention, cognition, word-finding and maintaining wakefulness; 2) clinically significant deficits on neuropsychological tests of information processing speed and attention; 3) gray and white matter hyperintensities in the reticular activating system on magnetic resonance imaging of the brain; 4) neuroendocrine evidence of impaired activation of the HPA axis. Many of these findings are identical to those documented following a variety of viral encephalitides, including acute poliovirus infection, lethargic encephalitis, Iceland Disease, myalgic encephalomyelitis, and, most recently, Chronic Fatigue Syndrome. The clinical, historic, neuropsychologic, neuroanatomic and physiologic parallels between poliovirus infection, post-polio fatigue and post-viral fatigue syndromes (PVFS) will be explored in an attempt to describe the pathophysiology of PVFS. The disinhibition of a putative Brain Fatigue Generator will be implicated as a cause of the subjective symptoms and objective signs that accompany PVFS. The results of a pilot placebo-controlled study of a dopamine 2 receptor agonist to treat post-polio fatigue will also be described.

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Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Dynamic electromyography and muscle biopsy changes in a 4-year follow-up: study of patients with a history of polio
Author: Stålberg E, Grimby G
Affiliation: Department of Clinical Neurophysiology, University Hospital, Uppsala, Sweden
Journal: Muscle & Nerve
Citation: Muscle Nerve. 1995 Jul;18(7):699-707
Publication Year and Month: 1995 07

Abstract: Eighteen patients who had had polio 29-56 years prior to the first investigation were studied on two occasions, 4 years apart. Isokinetic and isometric strength measurements and Macro EMG were performed in 28 legs. Muscle biopsy specimens were obtained on both occasions from 11 legs. On average the muscle strength was 56% of control values at the first examination, and decreased by another 8% during the observation period. The muscle fiber area was increased compared to that of controls and did not change significantly. Macro EMG, comprising muscle fiber area and number of muscle fibers, and/or single fiber EMG showed clear signs of reinnervation in all legs. The motor units at the first examination were increased 11-fold, on average, compared with age-matched control values. During the observation period, reinnervation continued and the size of motor units increased by another 56% as a result of ongoing denervation, that is, loss of neurons. This compensation was particularly pronounced in patients with stable conditions. The parameters studied did not reveal any definite pattern predicting future development of new muscle weakness in individual subjects.

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Category: Post-Polio Motor Unit

Title: Correlation of Electrophysiology with Pathology, Pathogenesis, and Anticholinesterase Therapy in Post-Polio Syndrome
Author: Neil R. Cashman and Daria A. Trojan
Affiliation: Department of Neurology, Montreal Neurological Institute and Hospital, McGill University
Journal: Annals of the New York Academy of Sciences
Citation: Reprinted from The Post-Polio Syndrome: Advances in the Pathogenesis and Treatment
Volume 753 [pp 138-150] of the Annals of the New York Academy of Sciences
May 25, 1995
Publication Year and Month: 1995 05

Abstract:

Conclusions: A great deal of data has been generated on PPS, and a great deal more will be generated before we understand the pathophysiology of this common and disabling disorder. Perhaps now, to guide future work and direct therapeutic approaches, it is best to think of the symptoms of PPS as due to two lesions of the motor unit: a "progressive lesion" and a "fluctuating lesion." The progressive lesion gives rise to the symptom of slowly progressive weakness, and is due to the degeneration of terminal axons (and perhaps motor neurons) over the course of years. This lesion, best articulated by Wiechers and Hubble,[18] has been difficult to objectify because of its indolent nature. However, significant clinical weakening has indeed been quantified by several groups, including Munsat and colleagues,[7] and Sonies and Dalakas.[53] The best objective "proof" of the progressive lesion at present is the appearance of muscle fiber atrophy in biopsies, isolated and in groups, suggesting ongoing "permanent" denervation.[22] Diminution of motor unit size over time, as suggested by the macro-EMG studies of Lange et al.,[32] are also consistent with this hypothesis, albeit more controversial.

The other lesion of the PPS motor unit, hypothesized as a "fluctuating lesion," may be due to dysfunction of terminal axons, which gives rise to symptoms (muscle fatigability, generalized fatigue, and a component of weakness) that can change over the course of minutes to days. The underlying pathophysiology of these symptoms may be due to critical enlargement of motor units with limitations of distal components subserving axonal conduction and NMJ transmission, and/or the constant remodeling of the motor unit which appears to occur in virtually every individual after recovery from paralytic poliomyelitis. The best objective evidence for this ongoing lesion is provided by innumerable electrophysiologic studies demonstrating unstable motor unit action potentials and decrement on repetitive stimulation with conventional EMG, increased SFEMG jitter, and a host ofother studies.[54] In addition, the widespread expression of N-CAM in muscle biopsies of post-polio subjects (sometimes exceeding 10% of fibers)[22] strongly suggests that axono-myofiber interactions are distinctly unstable and/or immature. Clearly, agents that support the integrity or function of motor axonal sprouts may improve or delay patient symptoms in PPS.

Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Electrodiagnostic Findings in 108 Consecutive Patients Referred to a Post-Polio Clinic – The Value of Routine Electrodiagnostic Studies
Author: Anne C. Gawne, Bao T. Pham, and Lauro S. Halstead

Affiliation:
Journal: Annals of the New York Academy of Sciences
Citation: The Post-Polio Syndrome: Advances in the Pathogenesis and Treatment Volume 753 pp 383-385 of the Annals of the New York Academy of Sciences May 25, 1995.
Publication Year and Month: 1995 05

Abstract: Many patients with a history of polio develop new symptoms including weakness, pain, fatigue, and changes in function, or post-polio syndrome (PPS).[1] Before a diagnosis of PPS is made, other diagnoses must first be ruled out. Assessment must be done in a comprehensive and coordinated manner.[2] Therefore, as part of our routine evaluation, we do an electromyogram/nerve conduction study (EMG/NCS) on every patient. During examinations on our clinic patients we began to notice (1) electrodiagnostic evidence of polio in limbs not previously felt to be involved; (2) a normal EMG, or evidence of another disease; and (3) EMG evidence consistent with additional neurological lesions, including compression neuropathies, peripheral neuropathies, and radiculopathies. A prospective study using a routine, standardized four-extremity electrodiagnostic protocol was done to quantify the frequency of these occurrences.

Conclusions: Our findings strongly support the value of a standardized four-extremity EMG/NCS as an adjuvant to a comprehensive history and physical examination. It helps to differentiate between old polio and other neurological diagnoses. There is a high prevalence of subclinical polio, which is important to know about in order to give proper recommendations regarding rest and activity. Given the frequency of risk factors for development of potentially treatable neurological lesions like CTS, early detection is valuable. We believe routine electrodiagnostic testing is essential for proper evaluation and management of the post-polio patient.

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Category: Post-Polio Motor Unit

Title: Muscle Function, Muscle Structure, and Electrophysiology in a Dynamic Perspective in Late Polio
Author: Gunnar Grimby, MD, PhD, Erik Stålberg, MD.
Affiliation:
Journal: NEW - PUT DETAILS IN CITATION FIELD
Citation: Gunnar Grimby, MD, PhD, Erik Stålberg, MD., Muscle Function, Muscle Structure, and Electrophysiology in a Dynamic Perspective in Late Polio, Chapter 2, pp 15-24.
Publication Year and Month: 1995

Abstract: The muscular impairment in patients with a history of polio varies from none to severe. The relationship between the degree of initial involvement and the effect of various compensatory mechanisms determines the clinical picture, which changes dynamically. Early and late recovery after poliomyelitis depend on a number of factors. Clinical improvement that appears within a few weeks after the acute phase is probably due to recovery in the excitability of functional, but not degenerated, motor neurons. Degeneration of neurons, causing peripheral denervation, is compensated by collateral sprouting, i.e., by nerve twigs branching off from surviving motor units overlapping with the denervated ones. This is most likely the main factor explaining recovery within the first 6-12 months. Another late compensatory process is the increase in size of the muscle fibers. As a result of these processes, normal muscle strength and presumably normal muscle volume can be seen despite a calculated loss exceeding 50% of the number of motor neurons.

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Category: Post-Polio Motor Unit

Title: Stimulation frequency-dependent neuromuscular junction transmission defects in patients with prior poliomyelitis
Author: Daria A. Trojan, Daniel Gendron and Neil R. Cashman
Affiliation: Department of Neurology, McGill University, Montreal Neurological Institute and Hospital
Journal:
Citation: Journal of the Neurological Sciences, 118 (1993) 150-157
Publication Year and Month: 1993 03

Abstract: Generalized fatigue and muscle fatiguability are major symptoms of post-poliomyelitis syndrome (PPS), and may be due to neuromuscular junction transmission defects, as suggested by increased jitter on single fiber electromyography (SFEMG). To determine the etiology of this defect, we studied jitter at low (1, 5 Hz) and high (10, 15, 20 Hz) frequency stimulation with stimulation SFEMG in 17 post-polio patients with muscle fatiguability, and in 9 normal controls. In 5 of 17 PPS patients and in 1 of 9 controls, jitter was significantly higher (unpaired t-test, P < 0.05) at high frequency stimulation (HFS). In the remaining PPS patients and controls there was no significant difference in jitter at high and low stimulation frequencies. PPS patients with increased jitter at HFS had a significantly longer time interval since acute polio (mean 48.5 years) than PPS patients without increased jitter at HFS (mean 40 years; P < 0.05), but were not distinguished by other historical or clinical criteria. We conclude that the neuromuscular junction defect in post-polio patients is similar to that observed in amyotrophic lateral sclerosis, and is probably due to ineffective conduction along immature nerve sprouts and exhaustion of acetylcholine stores. The appearance of an increase in jitter with HFS in post-polio patients may be dependent upon time after acute polio.

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Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: A rat model of the post-polio motor unit
Author: Pachter BR, Eberstein A
Affiliation: Department of Rehabilitation Medicine, New York University Medical Center, NY 10016
Journal: Orthopedics
Citation: Orthopedics. 1991 Dec; 14(12):1367-73
Publication Year and Month: 1991 12

Abstract: We examined the long-term effects of muscle usage on a rat model of the post-polio motor unit. Isometric tensions, type I and type II muscle fiber areas, the incidence of collateral sprouting, and motor endplate morphology were examined following 1, 3, 6, and 9 months of partial denervation in rat plantaris muscle. Full morphologic and functional stability of the expanded motor units occurred at 6 months post-partial denervation. Fiber hypertrophy was observed, possibly the result of compensatory work hypertrophy due to muscle overuse. Following 9 months of partial denervation and muscle overuse, the twitch and tetanic tensions and type I and type II muscle fiber areas were significantly reduced as compared to sham controls; angulated myofibers and group atrophy also were seen. The percent collateral sprouting, the number of terminal branches per endplate, and the endplate area were all increased, possibly a compensatory response to a decreased synthesis of neurotrophic factor(s) and/or transmitter-related components. These aging-like changes seem to occur earlier in chronically stressed, overenlarged, and overworked motor units.

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Category: Post-Polio Motor Unit

Title: Electrophysiology and Electrodiagnosis of the Post-Polio Motor Unit
Author: Daria A. Trojan, MD, Daniel Gendron, MD, Neil R. Cashman, MD
Affiliation:
Journal: Orthopedics
Citation: Orthopedics December 1991 Vol 14 No 12 1353-1361
Publication Year and Month: 1991 12

Abstract: Post-poliomyelitis syndrome refers to new symptoms that may occur years after recovery from poliomyelitis. The most common of these symptoms are new weakness, fatigue, and pain. This article describes electrodiagnostic studies -- conventional electromyography (EMG), single fiber electromyography (SFEMG), and macroelectromyography (macro-EMG) -- that have provided information on the post-polio motor unit and on the possible etiology of some post-polio syndrome symptoms. Muscular fatigue, and indirectly, general fatigue, may be due to neuromuscular junction transmission defects in some post-polio individuals, as suggested by reduction of the compound motor action potentials on repetitive stimulation, and increased jitter and blocking on SFEMG. Progressive weakness and atrophy in post-polio syndrome is probably due to a distal degeneration of post-polio motor units with resultant irreversible muscle fiber denervation. Electrodiagnostic evidence of ongoing denervation includes fibrillation and fasciculation potentials on conventional EMG, increased jitter and blocking on SFEMG, and smaller macro-EMG amplitudes in newly weakened postpolio muscles. However, even though electrodiagnostic studies have provided insight into the possible causes of some postpolio syndrome symptoms, no specific electrodiagnostic test for the syndrome is currently available.

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Outcome of Research: Not applicable

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Category: Post-Polio Motor Unit

Title: Late effects of polio: critical review of the literature on neuromuscular function
Author: Agre JC, Rodríquez AA, Tafel JA
Affiliation: University of Wisconsin - Madison Medical School
Journal: Archives of Physical Medicine and Rehabilitation
Citation: Arch Phys Med Rehabil. 1991 Oct; 72(11):923-31
Publication Year and Month: 1991 10

Abstract: Many individuals who have had poliomyelitis are now complaining of several new problems attributed to their former illness including muscle atrophy; fatigue; progressive weakness; and muscle, back, and joint pain. This paper critically examines the literature regarding the neuromuscular effects of poliomyelitis. Weakness resulting from poliomyelitis was due to destruction of anterior horn cells. After the illness, muscle strength was partially recovered as a result of several physiologic adaptive mechanisms including terminal sprouting and reinnervation, myofiber hypertrophy, and, possibly, myofiber type transformation. Several pathophysiologic and functional etiologies have been proposed for late neuromuscular deterioration, but none has been proven. In fact, to date, there is no objective evidence documenting progressive loss of strength in polio survivors. Studies attempting to differentiate polio survivors with and without symptoms of deterioration have resulted in conflicting results; however, it appears reasonable to conclude that symptomatic postpolio subjects had a more severe illness with greater loss of neuromuscular function. Exercise may be helpful for many postpolio patients, but the prescription must be tailored to the individual to avoid problems of overuse or excessive fatigue.

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Category: Post-Polio Motor Unit

Title: Electromyographic and morphological functional compensation in late poliomyelitis
Author: Einarsson G, Grimby G, Stålberg E
Affiliation: Department of Rehabilitation Medicine, Gothenburg University, Sweden
Journal: Muscle & Nerve
Citation: Muscle Nerve. 1990 Feb; 13(2):165-71
Publication Year and Month: 1990 02

Abstract: Patients with prior poliomyelitis may experience muscle function deterioration decades after onset of disease. The present study is aimed at describing electromyographic and morphometric evidence of muscular compensation and of on-going muscular instability. Ten subjects 42-62 years of age with onset of polio 25-52 years earlier were studied with macro EMG, single-fiber EMG (SFEMG), muscle strength measurement, and morphometrical analysis of muscle biopsies from the vastus lateralis muscle. SFEMG revealed increased fiber density (FD) and large macro-MUP potentials indicating pronounced reinnervation as compensation to loss of motor neurons. From electrophysiological data of motor unit size, morphometric measures of fiber size, and muscle strength data, the minimal degree of motor neuron loss was estimated to be greater than 70%.

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Category: Post-Polio Motor Unit

Title: Functional recovery – a major risk factor for the development of postpoliomyelitis muscular atrophy
Author: Klingman J, Chui H, Corgiat M, Perry J
Affiliation: Department of Neurology, University of Southern California School of Medicine, Los Angeles
Journal: Archives of Neurology
Citation: Arch Neurol. 1988 Jun;45(6):645-7
Publication Year and Month: 1988 06

Abstract: A retrospective study was undertaken to identify potential risk factors for the development of progressive postpoliomyelitis muscular atrophy (PPMA). Patients with PPMA (n = 57) were compared with patients with a history of poliomyelitis but without a history of progressive weakness (n = 49). Patients who later developed PPMA had histories of more widespread acute paralysis, but relatively greater functional recovery. They were less disabled, and reported higher recent activity levels. Seventy-nine percent of the total variance between the PPMA and control groups could be accounted for by recovery alone (ie, severity minus disability). Functional recovery is generally attributed to reinnervation of sarcomeres by collateral sprouting from surviving lower motor neurons. Since degree of recovery predicts the risk of developing PPMA, our findings suggest that enlarged motor units may carry an increased susceptibility for dysfunction and/or degeneration.

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Category: Post-Polio Motor Unit

Title: Late denervation in patients with antecedent paralytic poliomyelitis
Author: Cashman NR, Maselli R, Wollmann RL, Roos R, Simon R, Antel JP
Affiliation: Not stated
Journal: The New England Journal of Medicine
Citation: N Engl J Med. 1987 Jul 2; 317(1):7-12
Publication Year and Month: 1987 07

Abstract: The development of new weakness, fatigue, and pain decades after acute paralytic poliomyelitis is a recognized syndrome. We conducted a controlled study of this syndrome by analyzing clinical, electromyographic, and muscle-biopsy features in 18 patients with a history of poliomyelitis--13 reporting 1 to 20 years of new weakness and 5 without new symptoms. The patients with new weakness also reported new muscle atrophy (9 of 13) and fatigue (10 of 13), symptoms not reported by the controls. The age at the time of acute poliomyelitis, severity of poliomyelitis, residual disability, number of years since acute poliomyelitis, and age at the time of study were comparable in the weakening and control groups. Evidence of remote denervation consistent with antecedent poliomyelitis was demonstrated in all patients by electromyography or muscle biopsy or both. In addition, active denervation (as evidenced by spontaneous activity on conventional electromyography, increased jitter on single-fiber electromyography, or atrophic myofibers) was found in 12 patients in the weakening group and in all 5 controls. Immunohistochemical detection of myofibers expressing the neural-cell adhesion molecule corroborated ongoing denervation in both patient groups. When muscle data from both groups were pooled, correlations were observed between the extent of past reinnervation and the degree of ongoing motor-unit instability. We conclude that the extensive reinnervation of denervated muscle that occurs in paralytic poliomyelitis may be followed by late denervation of the previously reinnervated muscle fibers. Electromyographic and muscle-biopsy evidence of ongoing denervation does not distinguish between stable patients with prior paralytic poliomyelitis and those with new weakness.

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Category: Post-Polio Motor Unit

Title: Neurological manifestations of the post-polio syndrome
Author: Jubelt B, Cashman NR
Affiliation: Les Turner Amyotrophic Lateral Sclerosis Research Laboratory, Northwestern University Medical School, Chicago, Illinois
Journal: Critical Reviews in Neurobiology
Citation: Crit Rev Neurobiol. 1987;3(3):199-220
Publication Year and Month: 1987 03

Abstract: Patients with late effects of poliomyelitis, ie PPS, are being seen at an ever increasing frequency by general physicians, neurologists, and orthopedists. An appropriate time interval for the onset of late manifestations has elapsed since the major epidemics of poliomyelitis in the 1940s and 1950s. Post-polio neurological manifestations primarily include new weakness, atrophy, muscle pain, and fasciculations. Fortunately, the weakness is of a very slow, progressive nature. Abnormal laboratory studies include routine EMG, demonstrating chronic denervation; SFEMG, demonstrating increased fiber density, increased jitter, and blocking; and muscle biopsy most often revealing fiber-type grouping of chronic denervation and small isolated angular (or angulated) fibers and group atrophy in some series, both suggestive of active denervation. Unfortunately, both EMG and muscle biopsy studies suffer from a lack of specificity as they do not appear to distinguish asymptomatic from symptomatic (new weakness, PPMA) patients with prior poliomyelitis. Although the cause of PPMA is unknown, electrophysiological (SFEMG) and muscle biopsy studies suggest that the process involves a loss or dropout of axon terminals of reinnervated motor units. The axons terminal dropout could be due to dysfunction in the cell soma, the axon, or the terminals themselves. Whether motor neuron exhaustion, a persistent viral infection, or immune-mediated mechanisms play a role in the pathogenesis of the late weakness is unclear at present and will require further investigation. Treatment at this time is of a supportive nature. A major controversy involves the role of strengthening exercises in these patients since experimental animal studies suggest that excessive exercise of denervated muscles leads to increased weakness. Clearly, a better understanding of PPS and PPMA will allow more effective management of these patients’ problems and might also provide insight into other motor neuron and neuromuscular junction diseases.

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Category: Post-Polio Motor Unit

Title: A long-term follow-up study of patients with post-poliomyelitis neuromuscular symptoms
Author: Dalakas MC, Elder G, Hallett M, Ravits J, Baker M, Papadopoulos N, Albrecht P, Sever J
Affiliation: Not stated
Journal: The New England Journal of Medicine
Citation: N Engl J Med. 1986 Apr 10; 314(15):959-63
Publication Year and Month: 1986 04

Abstract: A “post-polio” syndrome characterized by new neuromuscular symptoms, including muscle weakness, may develop years after recovery from acute paralytic poliomyelitis. We studied 27 patients (mean age, 50.6 years) in whom new muscle weakness developed a mean of 28.8 years after recovery from acute polio. We reevaluated these patients during a mean follow-up period of 8.2 years (range, 4.5 to 20) after they were originally studied at the National Institutes of Health. The total mean follow-up period after the onset of new weakness was 12.2 years (range, 6 to 29). The patients were assessed with quantitative muscle testing, muscle biopsy, electromyography, and virologic and immunologic examination of the cerebrospinal fluid. Muscle strength had declined in all patients. The rate of decline averaged 1 percent per year. The decrease was irregular, with subjective plateau periods that ranged from 1 to 10 years. None of the patients had amyotrophic lateral sclerosis. Oligoclonal bands (IgG) were found in the cerebrospinal fluid of 7 of 13 patients studied, but no specific elevation of antibodies to poliovirus was observed in the cerebrospinal fluid. The newly affected muscles that were evaluated longitudinally with follow-up muscle biopsies and electromyography showed signs of chronic and new denervation. Groups of atrophic muscle fibers (group atrophy) and "neurogenic jitter" were not present. New post-polio muscle weakness is not a life-threatening form of motor-neuron deterioration. It appears that this weakness is not due to a loss of whole motor neurons, as in amyotrophic lateral sclerosis, but that it is due to a dysfunction of the surviving motor neurons that causes a slow disintegration of the terminals of individual nerve axons.

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Category: Post-Polio Motor Unit

Title: Vasomotor abnormalities as post-polio sequelae: functional and clinical implications
Author: Bruno RL, Johnson JC, Berman WS
Affiliation: Not stated
Journal: Orthopedics
Citation: Orthopedics. 1985 Jul; 8(7):865-9
Publication Year and Month: 1985 07

Abstract: Persons who had poliomyelitis report cold and discolored extremities and decreased muscle strength when exposed to mildly cool ambient temperatures. Bilateral digital cutaneous blood flow, skin temperature and median nerve latencies and amplitudes were measured at 30 degrees C, 25 degrees C and 20 degrees C in five post-polio subjects and age-matched controls. Cutaneous blood flow was lowest on the more affected side in the post-polio subjects but vasoconstriction with decreasing Ta was equal bilaterally in both groups. With decreasing Ta, median motor nerve latencies became clinically abnormal and “giant” sensory nerve potential amplitudes were seen in a majority of the post-polio subjects. It is concluded that an impairment of sympathetic vasoconstrictor outflow in post-polios allows passive dilatation and engorgement of the cutaneous venous capacitance beds. This promotes uncontrolled heat loss and causes cooling of nerve and muscle that is responsible for the impairment of muscle functioning and the abnormal electrophysiological findings.

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Category: Post-Polio Motor Unit

Title: Acute and latent effect of poliomyelitis on the motor unit as revealed by electromyography
Author: Wiechers DO
Affiliation: Not stated
Journal: Orthopedics
Citation: Orthopedics. 1985 Jul; 8(7):870-2
Publication Year and Month: 1985 07

Abstract: When polio virus attacks the motor neuron it may be completely destroyed, damaged, or unaffected. Muscle fibers of a destroyed motor neuron are orphaned or reinnervated. Nearby functioning motor units will then send terminal axon sprouts to reinnervate the orphaned muscle fibers. If there are too many orphaned muscle fibers and not enough surviving motor units to reinnervate them, the orphaned muscle fibers will continue to fibrillate until they atrophy and die. The resultant effect of poliomyelitis upon the affected muscle is an overall loss of motor units with the remaining units innervating many more muscle fibers than they originally did. There appears to be a late effect of polio upon these larger reinnervated motor units. After approximately 20 to 30 years, impulse transmission to the muscle fibers of the large reinnervated motor unit begins to fail. These transmission difficulties increase with age and time from recovery. These late onset transmission abnormalities may be factors in patient complaints of fatigue and progressive weakness.

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There are currently 19 papers in this category.

Outcomes of Research or Clinical Trials Activity Levels Acute Flaccid Paralysis Ageing Anaerobic Threshold Anaesthesia Assistive Technology Brain Cardiorespiratory Cardiovascular Clinical Evaluation Cold Intolerance Complementary Therapies Continence Coping Styles and Strategies Cultural Context Diagnosis and Management Differential Diagnosis Drugs Dysphagia Dysphonia Epidemiology Exercise Falls Fatigue Fractures Gender Differences Immune Response Inflammation Late Effects of Polio Muscle Strength Muscular Atrophy Orthoses Pain Polio Immunisation Post-Polio Motor Unit Psychology Quality of Life Renal Complications Respiratory Complications and Management Restless Legs Syndrome Sleep Analaysis Surgery Vitality Vocational Implications