Pathogenetic mechanisms of post-polio syndrome: morphological, electrophysiological, virological, and immunological correlations

Post-polio syndrome is not a dysimmune condition

BACKGROUND

Poliomyelitis is a global disabling disease affecting 12-20 million of people. Post poliomyelitis syndrome (PPS) may affect up to 80% of polio survivors: increased muscle weakness, pain, fatigue, functional decline. It relies on aging of an impaired neuro-muscular system with ongoing denervation processes. A late involvement of humoral or cellular pro-inflammatory phenomena is also suspected.

AIM

To assess the dysimmune hypothesis of PPS by comparing lymphocyte subpopulations and humoral immune factors between PPS patients and controls.

DESIGN

Cross-sectional study.

SETTING

Montpellier University Hospital.

POPULATION

Forty-seven PPS and 27 healthy controls.

METHODS

PPS patients and controls were compared on their lymphocyte subpopulations and humoral immune factors (IL-1β, IL-6, IL-8, IL-17, IL-21, IL-22, IL-23, IFN-γ, TNF-α, GM-CSF, RANTES, MCP1, MIP-3a, IL-10, TGF-β, IL4, IL13). Patients were further compared according to their dominant clinical symptoms. Sample size guaranteed a power >90% for all comparisons.

RESULTS

PPS patients and controls were comparable in gender, age and corpulence. Most patients had lower limb motor sequelae (N.=45, 95.7%), a minority had upper limb motor impairment (N.=16, 34.0%). Forty-five were able to walk (94%), 35/45 with technical aids. The median of the two-minute walking test was 110 meters (interquartile range 55; 132). Eighteen (38%) required help in their daily life. Their quality of life was low (SF36). All described an increased muscular weakness, 40 (85%) a general fatigue, and 39 (83%) muscular or joint pain. Blood count, serum electrolytes, T and B lymphocyte subpopulations and cytokines were comparable between patients and controls, except for creatine phospho kinase that was significantly higher in PPS patients. None of these variables differed between the 20/47 patients whose late main symptoms were pain or fatigue, and other patients.

CONCLUSIONS

Our results suggest that PPS is not a dysimmune disease.

CLINICAL REHABILITATION IMPACT

Our results do not sustain immunotherapy for PPS. Our work suggest that PPS may be mostly linked to physiological age-related phenomena in a disabled neuromuscular condition. Thus, our results emphasize the role of prevention and elimination of aggravating factors to avoid late functional worsening, and the importance of rehabilitation programs that should be adapted to patients' specific conditions.

Post-Polio Syndrome Revisited

Post-polio syndrome (PPS) is characterized by recrudescence or worsening of motor neuron disease symptoms decades after recovery from acute paralytic poliovirus infection, i.e., poliomyelitis. PPS afflicts between 25% and 40% of poliomyelitis survivors and mimics motor neuron diseases (MNDs), such as amyotrophic lateral sclerosis (ALS), due to its selective impairment, degeneration, or death of motor neurons in the brainstem and spinal cord. Herein, we report a case of PPS in a 68-year-old man with a remote history of bulbar and cervical cord involvement by poliomyelitis, review the relevant literature, and contrast the salient histopathologic features that distinguish our case of PPS from ALS.

Critical illness-associated weakness and related motor disorders

Weakness of limb and respiratory muscles that occurs in the course of critical illness has become an increasingly common and serious complication of adult and pediatric intensive care unit patients and a cause of prolonged ventilatory support, morbidity, and prolonged hospitalization. Two motor disorders that occur singly or together, namely critical illness polyneuropathy and critical illness myopathy, cause weakness of limb and of breathing muscles, making it difficult to be weaned from ventilatory support, commencing rehabilitation, and extending the length of stay in the intensive care unit, with higher rates of morbidity and mortality. Recovery can take weeks or months and in severe cases, and may be incomplete or absent. Recent findings suggest an improved prognosis of critical illness myopathy compared to polyneuropathy. Prevention and treatment are therefore very important. Its management requires an integrated team approach commencing with neurologic consultation, creatine kinase (CK) measurement, detailed electrodiagnostic, respiratory and neuroimaging studies, and potentially muscle biopsy to elucidate the etiopathogenesis of the weakness in the peripheral and/or central nervous system, for which there may be a variety of causes. These tenets of care are being applied to new cases and survivors of the coronavirus-2 disease pandemic of 2019. This chapter provides an update to the understanding and approach to critical illness motor disorders.

Smouldering multiple sclerosis: the 'real MS'

Using a philosophical approach or deductive reasoning, we challenge the dominant clinico-radiological worldview that defines multiple sclerosis (MS) as a focal inflammatory disease of the central nervous system (CNS). We provide a range of evidence to argue that the 'real MS' is in fact driven primarily by a smouldering pathological disease process. In natural history studies and clinical trials, relapses and focal activity revealed by magnetic resonance imaging (MRI) in MS patients on placebo or on disease-modifying therapies (DMTs) were found to be poor predictors of long-term disease evolution and were dissociated from disability outcomes. In addition, the progressive accumulation of disability in MS can occur independently of relapse activity from early in the disease course. This scenario is underpinned by a more diffuse smouldering pathological process that may affect the entire CNS. Many putative pathological drivers of smouldering MS can be potentially modified by specific therapeutic strategies, an approach that may have major implications for the management of MS patients. We hypothesise that therapeutically targeting a state of 'no evident inflammatory disease activity' (NEIDA) cannot sufficiently prevent disability accumulation in MS, meaning that treatment should also focus on other brain and spinal cord pathological processes contributing to the slow loss of neurological function. This should also be complemented with a holistic approach to the management of other systemic disease processes that have been shown to worsen MS outcomes.

Update on Intravenous Immunoglobulin in Neurology: Modulating Neuro-autoimmunity, Evolving Factors on Efficacy and Dosing and Challenges on Stopping Chronic IVIg Therapy

In the last 25 years, intravenous immunoglobulin (IVIg) has had a major impact in the successful treatment of previously untreatable or poorly controlled autoimmune neurological disorders. Derived from thousands of healthy donors, IVIg contains IgG1 isotypes of idiotypic antibodies that have the potential to bind pathogenic autoantibodies or cross-react with various antigenic peptides, including proteins conserved among the "common cold"-pre-pandemic coronaviruses; as a result, after IVIg infusions, some of the patients' sera may transiently become positive for various neuronal antibodies, even for anti-SARS-CoV-2, necessitating caution in separating antibodies derived from the infused IVIg or acquired humoral immunity. IVIg exerts multiple effects on the immunoregulatory network by variably affecting autoantibodies, complement activation, FcRn saturation, FcγRIIb receptors, cytokines, and inflammatory mediators. Based on randomized controlled trials, IVIg is approved for the treatment of GBS, CIDP, MMN and dermatomyositis; has been effective in, myasthenia gravis exacerbations, and stiff-person syndrome; and exhibits convincing efficacy in autoimmune epilepsy, neuromyelitis, and autoimmune encephalitis. Recent evidence suggests that polymorphisms in the genes encoding FcRn and FcγRIIB may influence the catabolism of infused IgG or its anti-inflammatory effects, impacting on individualized dosing or efficacy. For chronic maintenance therapy, IVIg and subcutaneous IgG are effective in controlled studies only in CIDP and MMN preventing relapses and axonal loss up to 48 weeks; in practice, however, IVIg is continuously used for years in all the aforementioned neurological conditions, like is a "forever necessary therapy" for maintaining stability, generating challenges on when and how to stop it. Because about 35-40% of patients on chronic therapy do not exhibit objective neurological signs of worsening after stopping IVIg but express subjective symptoms of fatigue, pains, spasms, or a feeling of generalized weakness, a conditioning effect combined with fear that discontinuing chronic therapy may destabilize a multi-year stability status is likely. The dilemmas of continuing chronic therapy, the importance of adjusting dosing and scheduling or periodically stopping IVIg to objectively assess necessity, and concerns in accurately interpreting IVIg-dependency are discussed. Finally, the merit of subcutaneous IgG, the ineffectiveness of IVIg in IgG4-neurological autoimmunities, and genetic factors affecting IVIg dosing and efficacy are addressed.

Treatment with L-Citrulline in patients with post-polio syndrome: A single center, randomized, double blind, placebo-controlled trial

This single-centered, randomized, double-blind, placebo-controlled study reports the results of L-Citrulline treatment for 24 weeks in patients with post-polio syndrome (PPS). Twenty-nine patients were randomized and assigned into receiving a treatment of 15 g L-Citrulline or placebo. The primary endpoint was the change of the 6 min walking distance test. Secondary endpoints included motor function measure, quantitative muscle strength, quantitative MRI and self-reported impairment questionnaires. Patients receiving L-Citrulline walked 17.5 longer in the 6 min walking distance test when compared to placebo group, however not statistically significant (95% CI = -14.69; 49.68, p = 0.298). None of the secondary endpoints showed a statistically significant change in the L-Citrulline group when compared to placebo group. The motor function measure showed a change of -0.78 (95% CI= [-3.39; 1.83] p = 0.563). Muscle degeneration of leg muscles assessed with quantitative MRI indicated no significant change (estimate= -0.01, 95% CI =-0.13; 0.11, p = 0.869). L-Citrulline was safe and well tolerated. In conclusion, administration of 15 g L-Citrulline daily for 24 weeks to patients with PPS showed no beneficial treatment effect in timed muscle function.

Follistatin-induced muscle hypertrophy in aged mice improves neuromuscular junction innervation and function

Sarcopenia, or age-related loss of muscle mass and strength, is an important contributor to loss of physical function in older adults. The pathogenesis of sarcopenia is likely multifactorial, but recently the role of neurological degeneration, such as motor unit loss, has received increased attention. Here, we investigated the longitudinal effects of muscle hypertrophy (via overexpression of human follistatin, a myostatin antagonist) on neuromuscular integrity in C57BL/6J mice between the ages of 24 and 27 months. Following follistatin overexpression (delivered via self-complementary adeno-associated virus subtype 9 injection), muscle weight and torque production were significantly improved. Follistatin treatment resulted in improvements of neuromuscular junction innervation and transmission but had no impact on age-related losses of motor units. These studies demonstrate that follistatin overexpression-induced muscle hypertrophy not only increased muscle weight and torque production but also countered age-related degeneration at the neuromuscular junction in mice.

Postpolio Syndrome: A Review of Lived Experiences of Patients

Postpolio syndrome (PPS) refers to a group of conditions that are present in patients, years after recovery from initial acute paralytic poliomyelitis. About 15%-80% of 20 million polio survivors worldwide will experience exacerbation of symptoms which typically appear 15-30 years after the resolution of initial poliomyelitis. Symptoms include new muscle weakness, fatigue, myalgia, joint pain, dysphagia, and difficulty breathing. Other reported symptoms include cold intolerance, sleep disorder, dysphonia, loss of stamina, musculoskeletal deformities, cardiovascular disorders, psychosocial problems, and restless legs syndrome. These symptoms are attributed to the superimposed neuronal loss of aging with inflammatory mechanisms, but without any convincing evidence of viral reactivation. Risk factors include female gender, respiratory symptoms, normal aging, permanent disability caused by motor neuron damage, muscle overuse and disuse, aging, and immunologic mechanisms. Hypothyroidism-induced myopathy and fibromyalgia are a differential diagnosis for PPS, and exclusion diagnosis is required as confirmatory criteria for PPS. The symptoms of PPS presented determine the course of management.

Post-polio Syndrome: More Than Just a Lower Motor Neuron Disease

Post-polio syndrome (PPS) is a neurological condition that affects polio survivors decades after their initial infection. Despite its high prevalence, the etiology of PPS remains elusive, mechanisms of progression are poorly understood, and the condition is notoriously under-researched. While motor dysfunction is a hallmark feature of the condition, generalized fatigue, sleep disturbance, decreased endurance, neuropsychological deficits, sensory symptoms, and chronic pain are also often reported and have considerable quality of life implications in PPS. The non-motor aspects of PPS are particularly challenging to evaluate, quantify, and treat. Generalized fatigue is one of the most distressing symptoms of PPS and is likely to be multifactorial due to weight-gain, respiratory compromise, poor sleep, and polypharmacy. No validated diagnostic, monitoring, or prognostic markers have been developed in PPS to date and the mainstay of therapy centers on symptomatic relief and individualized rehabilitation strategies such as energy conservation and muscle strengthening exercise regimes. Despite a number of large clinical trials in PPS, no effective disease-modifying pharmacological treatments are currently available.

Post-polio syndrome, report of two cases

El síndrome pospoliomielitis se reconoce como un trastorno neurológico que aparece décadas después de un episodio agudo de poliomielitis y disminuye la capacidad funcional hasta afectar las actividades cotidianas. El evento ocurre en un 20-80% de las personas que fueron afectadas por el virus de la poliomielitis, es más frecuente en las mujeres y existe una relación directa entre el riesgo de padecer este síndrome y el grado de severidad de las secuelas de la polio. El objetivo de este artículo es la presentación de dos casos clínicos de pacientes que presentaron este síndrome después de cerca de cuarenta años de haber presentado un episodio de poliomielitis.  Se cuestiona el concepto de la poliomielitis como una enfermedad estática; además, en los casos presentados esta patología constituye un proceso de difícil diagnóstico y manejo. El impacto psicológico y funcional en los pacientes se asume como un reto para el profesional de salud, puesto que se deben identificar las necesidades clínicas y reducir las barreras asistenciales existentes en la actualidad.

Enteroviral Infection: The Forgotten Link to Amyotrophic Lateral Sclerosis?

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that primarily attacks motor neurons in the brain and spinal cord, leading to progressive paralysis and ultimately death. Currently there is no effective therapy. The majority of ALS cases are sporadic, with no known family history; unfortunately the etiology remains largely unknown. Contribution of Enteroviruses (EVs), a family of positive-stranded RNA viruses including poliovirus, coxsackievirus, echovirus, enterovirus-A71 and enterovirus-D68, to the development of ALS has been suspected as they can target motor neurons, and patients with prior poliomyelitis show a higher risk of motor neuron disease. Multiple efforts have been made to detect enteroviral genome in ALS patient tissues over the past two decades; however the clinical data are controversial and a causal relationship has not yet been established. Recent evidence from in vitro and animal studies suggests that enterovirus-induced pathology remarkably resembles the cellular and molecular phenotype of ALS, indicating a possible link between enteroviral infection and ALS pathogenesis. In this review, we summarize the nature of enteroviral infection, including route of infection, cells targeted, and viral persistence within the central nervous system (CNS). We review the molecular mechanisms underlying viral infection and highlight the similarity between viral pathogenesis and the molecular and pathological features of ALS, and finally, discuss the potential role of enteroviral infection in frontotemporal dementia (FTD), a disease that shares common clinical, genetic, and pathological features with ALS, and the significance of anti-viral therapy as an option for the treatment of ALS.

Treatment with L-citrulline in patients with post-polio syndrome: study protocol for a single-center, randomised, placebo-controlled, double-blind trial

BACKGROUND

Post-polio syndrome (PPS) is a condition that affects polio survivors years after recovery from an initial acute infection by the Poliomyelitis virus. Most often, patients who suffered from polio start to experience gradual new weakening in muscles, a gradual decrease in the size of muscles (muscle atrophy) and fatigue years after the acute illness. L-citrulline is known to change muscular metabolism synthesis by raising nitric oxide (NO) levels and increasing protein synthesis. This investigator-initiated, randomised, placebo-controlled, double-blind, trial aims to demonstrate that L-citrulline positively influences muscle function and increases muscular energy production in patients with PPS.

METHODS/DESIGN

Thirty ambulant PPS patients will be recruited in Switzerland. Patients will be randomly allocated to one of the two arms of the study (placebo:verum 1:1). After a 24-week run-in phase to observe natural disease history and progression, participants will be treated either with L-citrulline or placebo for 24 weeks. The primary endpoint is change in the 6-min Walking Distance Test. Secondary endpoints will include motor function measure, quantitative muscle force, quantitative muscle magnetic resonance imaging and magnetic resonance spectroscopy and serum biomarker laboratory analysis DISCUSSION: The aim of this phase IIa trial is to determine if treatment with L-citrulline shows a positive effect on clinical function and paraclinical biomarkers in PPS. If treatment with L-citrulline shows positive effects, this might represent a cost-efficient symptomatic therapy for PPS patients.

TRIAL REGISTRATION

ClinicalTrial.gov, ID: NCT02801071 . Registered on 6 June 2016.

Efficacy of Intravenous Immunoglobulin in Neurological Diseases

Owing to its anti-inflammatory efficacy in various autoimmune disease conditions, intravenous immunoglobulin (IVIG)-pooled IgG obtained from the plasma of several thousands individuals-has been used for nearly three decades and is proving to be efficient in a growing number of neurological diseases. IVIG therapy has been firmly established for the treatment of Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, and multifocal motor neuropathy, either as first-line therapy or adjunctive treatment. IVIG is also recommended as rescue therapy in patients with worsening myasthenia gravis and is beneficial as a second-line therapy for dermatomyositis and stiff-person syndrome. Subcutaneous rather than intravenous administration of IgG is gaining momentum because of its effectiveness in patients with primary immunodeficiency and the ease with which it can be administered independently from hospital-based infusions. The demand for IVIG therapy is growing, resulting in rising costs and supply shortages. Strategies to replace IVIG with recombinant products have been developed based on proposed mechanisms that confer the anti-inflammatory activity of IVIG, but their efficacy has not been tested in clinical trials. This review covers new developments in the immunobiology and clinical applications of IVIG in neurological diseases.

Post-poliomyelitis syndrome as a possible viral disease

This review summarizes current concepts on post-polio syndrome (PPS), a condition that may arise in polio survivors after partial or complete functional recovery followed by a prolonged interval of stable neurological function. PPS affects 15-20 million people worldwide. Epidemiological data are reported, together with the pathogenic pathways that possibly lead to the progressive degeneration and loss of neuromuscular motor units. As a consequence of PPS, polio survivors experience new weakness, generalized fatigue, atrophy of previously unaffected muscles, and a physical decline that may culminate in the loss of independent life. Emphasis is given to the possible pathogenic role of persistent poliovirus infection and chronic inflammation. These factors could contribute to the neurological and physical decline in polio survivors. A perspective is then given on novel anti-poliovirus compounds and monoclonal antibodies that have been developed to contribute to the final phases of polio eradication. These agents could also be useful for the treatment or prevention of PPS. Some of these compounds/antibodies are in early clinical development. Finally, current clinical trials for PPS are reported. In this area, the intravenous infusion of normal human immunoglobulins appears both feasible and promising.

Does a subgroup of postpolio patients need different management?

Throughout the 30 years of postpolio syndrome (PPS) research, there have been many puzzling anomalies in the data and not enough information to make sense of them. It is therefore welcome that Winberg et al have examined physical activity in relation to life satisfaction, sex and age. They hypothesized that activity would decrease with age and found the opposite. This result is not so surprising as Ostlund et al found that vitality was associated with older age and that younger age was associated with more pain, increasing physical fatigue, decreasing sleep quality and reducing activity. This commentary will examine past postpolio research with unexpected results in order to describe a subgroup of patients who may be more susceptible to overusing muscles and have particular exercise and activity needs.

Comparing axonal excitability in past polio to amyotrophic lateral sclerosis

INTRODUCTION

Poliomyelitis causes selective destruction of anterior horn cells and usually has a stable disease course post-infection. We assessed the excitability characteristics in patients with a stable course after past poliomyelitis and compared them with changes described in amyotrophic lateral sclerosis (ALS).

METHODS

The excitability characteristics of motor and sensory nerves were studied in 10 subjects with stable past poliomyelitis.

RESULTS

Motor rheobase was increased, but there were no significant changes in strength-duration properties or depolarizing threshold electrotonus, as have been seen in previous studies of ALS.

CONCLUSIONS

There is minimal change in axonal excitability properties in patients with stable past poliomyelitis. The results may signify sufficient compensation in the stable state of the disease. Increased subexcitability in 1 subject with demonstrable hyperexcitability may represent compensation for increased ectopic activity rather than a different process in surviving motor neurons. Muscle Nerve 50: 602-604, 2014.

Relationships between diabetes and cognitive impairment

Epidemics of obesity, diabetes, nonalcoholic fatty liver disease, and cognitive impairment/Alzheimer disease have emerged over the past 3 to 4 decades. These diseases share in common target-organ insulin resistance with a constellation of molecular and biochemical abnormalities that lead to organ/tissue degeneration over time. This article discusses the fundamental links among these diseases and how peripheral organ insulin resistance diseases contribute to cognitive impairment and neurodegeneration. A future role of endocrinologists and diabetologists could be to provide integrative diagnostic and treatment approaches for this collection of diseases that seem to share pathophysiological and pathogenetic bases.

A Classificacao Internacional de Doencas, a Familia de Classificacoes Internacionais, a CID-11 e a Sindrome Pos-Poliomielite

The first International Classification of Diseases (ICD) was approved in 1893 and since then it has been periodically reviewed. The last, 10th revision (ICD-10), was approved in 1989. Since 1989, it was possible to update from ICD revisions, which did not happen before. The next revision (ICD-11) would probably be published in 2015. In 1989, mechanisms were established to update ICD-10, through the creation of the Morbidity Reference Group (MbRG) in 1997 and the Update and Revision Committee (URC) in 2000. The Morbidity Reference Group (MbRG) was created in 2007 to discuss in more detail the issues to update morbidity. A specific code in ICD was not included in the revision of ICD-10 in 1989 for the post-polio syndrome (PPS). However, the ICD new code G14 for PPS was included in ICD-10 since 2010.

Adaptive and maladaptive motor axonal sprouting in aging and motoneuron disease

Motor unit (MU) enlargement by sprouting is an important compensatory mechanism for loss of functional MUs during normal aging and neuromuscular disease. Perisynaptic Schwann cells at neuromuscular junctions extend processes that bridge between denervated and reinnervated endplates, and guide axonal sprouts to reinnervate the denervated endplates. In a rat model of partial denervation, high levels of daily neuromuscular activity have been shown to inhibit the outgrowth of sprouts by preventing Schwann cell bridging. In this review, we consider (1) the relative roles of increasing levels of oxidative stress and neuromuscular activity to the destabilization of neuromuscular junctions with age and disease, and (2) how a progressive increase in the neuromuscular activity of declining numbers of functional MUs contributes to the progressive failure of adaptive sprouting and, in turn, to the progressive muscle weakness in the motoneuron diseases of post-polio syndrome and amyotrophic lateral sclerosis. We conclude that there is a time-related progression of MU loss, adaptive sprouting followed by maladaptive sprouting, and continuing recession of terminals during normal aging. The progression is accelerated in motoneuron disease, progressing more rapidly in the post-polio syndrome after prolonged denervation and extremely rapidly in ALS.

Macro electromyography and motor unit number index in the tibialis anterior muscle: differences and similarities in characterizing motor unit properties in prior polio

Our objective was to establish the usefulness of the noninvasive method of the motor unit number index (MUNIX) in a large muscle and to study how macro electromyography (EMG) and MUNIX complement each other in describing the motor units (MUs) in prior polio. MUNIX and macro EMG were performed in 48 tibialis anterior muscles in 33 prior polio patients. In addition, the reproducibility of MUNIX was investigated. It is shown that MUNIX can be used to characterize MUs with high reproducibility, even in a large muscle. As judged by MUNIX values, the patients had a 25% reduction of motor neurons, whereas the macro EMG indicated a loss of 60% of the neurons. Macro EMG showed more pronounced changes compared with control material than the MUNIX. One of the reasons for this finding may be the difference in MU populations studied with the two methods.

Traumatic brain injury: a disease process, not an event

Traumatic brain injury (TBI) is seen by the insurance industry and many health care providers as an "event." Once treated and provided with a brief period of rehabilitation, the perception exists that patients with a TBI require little further treatment and face no lasting effects on the central nervous system or other organ systems. In fact, TBI is a chronic disease process, one that fits the World Health Organization definition as having one or more of the following characteristics: it is permanent, caused by non-reversible pathological alterations, requires special training of the patient for rehabilitation, and/or may require a long period of observation, supervision, or care. TBI increases long-term mortality and reduces life expectancy. It is associated with increased incidences of seizures, sleep disorders, neurodegenerative diseases, neuroendocrine dysregulation, and psychiatric diseases, as well as non-neurological disorders such as sexual dysfunction, bladder and bowel incontinence, and systemic metabolic dysregulation that may arise and/or persist for months to years post-injury. The purpose of this article is to encourage the classification of TBI as the beginning of an ongoing, perhaps lifelong process, that impacts multiple organ systems and may be disease causative and accelerative. Our intent is not to discourage patients with TBI or their families and caregivers, but rather to emphasize that TBI should be managed as a chronic disease and defined as such by health care and insurance providers. Furthermore, if the chronic nature of TBI is recognized by government and private funding agencies, research can be directed at discovering therapies that may interrupt the disease processes months or even years after the initiating event.

Update on current and emerging treatment options for post-polio syndrome

Post-polio syndrome (PPS) refers to the clinical deterioration experienced by many polio survivors several decades after their acute illness. The symptoms are new muscle weakness, decreased muscle endurance, fatigue, muscle pain, joint pain, cold intolerance, and this typical clinical entity is reported from different parts of the world. The pathophysiology behind PPS is not fully understood, but a combination of distal degeneration of enlarged motor units caused by increased metabolic demands and the normal aging process, in addition to inflammatory mechanisms, are thought to be involved. There is no diagnostic test for PPS, and the diagnosis is based on a proper clinical workup where all other possible explanations for the new symptoms are ruled out. The basic principle of management of PPS lies in physical activity, individually tailored training programs, and lifestyle modification. Muscle weakness and muscle pain may be helped with specific training programs, in which training in warm water seems to be particularly helpful. Properly fitted orthoses can improve the biomechanical movement pattern and be energy-saving. Fatigue can be relieved with lifestyle changes, assistive devices, and training programs. Respiratory insufficiency can be controlled with noninvasive respiratory aids including biphasic positive pressure ventilators. Pharmacologic agents like prednisone, amantadine, pyridostigmine, and coenzyme Q10 are of no benefit in PPS. Intravenous immunoglobulin (IVIG) has been tried in three studies, all having positive results. IVIG could probably be a therapeutic alternative, but the potential benefit is modest, and some important questions are still unanswered, in particular to which patients this treatment is useful, the dose, and the therapeutic interval.

Inflammation in neurodegenerative diseases

Neurodegeneration, the slow and progressive dysfunction and loss of neurons and axons in the central nervous system, is the primary pathological feature of acute and chronic neurodegenerative conditions such as Alzheimer's disease and Parkinson's disease, neurotropic viral infections, stroke, paraneoplastic disorders, traumatic brain injury and multiple sclerosis. Despite different triggering events, a common feature is chronic immune activation, in particular of microglia, the resident macrophages of the central nervous system. Apart from the pathogenic role of immune responses, emerging evidence indicates that immune responses are also critical for neuroregeneration. Here, we review the impact of innate and adaptive immune responses on the central nervous system in autoimmune, viral and other neurodegenerative disorders, and discuss their contribution to either damage or repair. We also discuss potential therapies aimed at the immune responses within the central nervous system. A better understanding of the interaction between the immune and nervous systems will be crucial to either target pathogenic responses, or augment the beneficial effects of immune responses as a strategy to intervene in chronic neurodegenerative diseases.

Fear of falling, balance confidence and health-related quality of life in individuals with postpolio syndrome

The purposes of this study were to examine prevalence of fear of falling (FOF) and decreased balance confidence in individuals with postpolio syndrome (PPS) and to determine whether balance confidence was correlated with health-related quality of life (HRQOL) in this population. A survey, which included demographic questions, the Activities-specific Balance Confidence (ABC) Scale, and the MOS SF-36v2, was made available by mail and electronically to individuals with PPS. Descriptive and correlation statistics were used to analyze the responses. Fear of falling was reported in 95% of respondents, with 80% indicating that FOF affected their quality of life. Median ABC score (42 of 100), physical component score (27 of 100), and mental component score (47 of 100) were below average compared with the general population. A moderate correlation (r = 0.4; p < 0.001) was found between balance confidence and the physical component score of HRQOL in PPS. There was an overwhelming presence of FOF and severely impaired balance confidence in the majority of those with PPS. A fair correlation between the physical functioning component of HRQOL and balance confidence was noted in this population.

Identification of novel candidate protein biomarkers for the post-polio syndrome - implications for diagnosis, neurodegeneration and neuroinflammation

Survivors of poliomyelitis often develop increased or new symptoms decades after the acute infection, a condition known as post-polio syndrome (PPS). The condition affects 20-60% of previous polio patients, making it one of the most common causes of neurological deficits worldwide. The underlying pathogenesis is not fully understood and accurate diagnosis is not feasible. Herein we investigated whether it was possible to identify proteomic profile aberrations in the cerebrospinal fluid (CSF) of PPS patients. CSF from 15 patients with well-defined PPS were analyzed for protein expression profiles. The results were compared to data obtained from nine healthy controls and 34 patients with other non-inflammatory diseases which served as negative controls. In addition, 17 samples from persons with secondary progressive multiple sclerosis (SPMS) were added as relevant age-matched references for the PPS samples. The CSF of persons with PPS displayed a disease-specific and highly predictive (p=0.0017) differential expression of five distinct proteins: gelsolin, hemopexin, peptidylglycine alpha-amidating monooxygenase, glutathione synthetase and kallikrein 6, respectively, in comparison with the control groups. An independent ELISA confirmed the increase of kallikrein 6. We suggest that these five proteins should be further evaluated as candidate biomarkers for the diagnosis and development of new therapies for PPS patients.

Physical therapist management following rotator cuff repair for a patient with postpolio syndrome

BACKGROUND AND PURPOSE

Postpoliomyelitis sequelae, such as gait instability and progressive weakness, predispose people with postpolio syndrome to secondary disabilities. With aging, people who depend on their upper extremities to accommodate lower-extremity deficits may anticipate overuse injuries. The purpose of this case report is to describe the use of mobilization and exercise in postoperative rehabilitation of rotator cuff surgery on a patient with postpolio syndrome.

CASE DESCRIPTION

A 48-year-old woman with postpolio syndrome had rotator cuff surgical repair followed by physical therapy intervention. Maitland mobilization and mild functional exercises were chosen to avoid triggering fatigue.

OUTCOMES

Measurements taken preoperatively, before and after physical therapy intervention, and 2 years after intervention showed return to independent status with excellent retention.

DISCUSSION

No fatigue or overuse weakness was encountered. This is the first case report to document physical therapy following rotator cuff repair in a patient with postpolio syndrome.

Role of IVIg in autoimmune, neuroinflammatory and neurodegenerative disorders of the central nervous system: present and future prospects

INTRODUCTION

Although IVIg is highly effective in several autoimmune neuromuscular disorders (neuropathies, myopathies and neuromuscular junction disorders), its effectiveness in autoimmune or neuroinflammatory CNS diseases, with the exception of multiple sclerosis, has not been explored. Emerging data suggest that IVIg may have a role not only in certain antibody-mediated CNS diseases but also in some neurodegenerative disorders associated with "neuroinflammation" mediated by proinflammatory cytokines.

METHODS

Data from a previously reported controlled study conducted in patients with stiff person syndrome (SPS) are presented as a paradigm of a CNS disorder associated with specific autoantibodies responding to IVIg. Emerging data using IVIg in various neuroinflammatory and neurodegenerative conditions such as Alzheimers disease, postpolio syndrome (PPS), fibrotic disorders, chronic painful conditions and narcoplepsy are summarized.

RESULTS

On the basis of a double-blind placebo-controlled trial conducted in SPS patients with high anti-GAD antibodies, IVIg was shown to be effective resulting in improvement of stiffness and heightened sensitivity scores and increasing the patients' ability to carry out daily activities. In SPS, IVIg also suppressed the anti-GAD antibodies titers probably via an anti-idiotypic effect. A controlled study in patients with PPS, showed reduction in cytokines in serum and CSF with concomitant improvement in the patients' strength and ability to carry out their daily activities. The effect of IVIg in a small number of patients with Alzheimer's disease was promising by reducing the ADAS-cog scores, suggesting a reversal of disease progression. IVIg has been shown to have an effect on tissue fibrosis and in certain subacute painful conditions by suppressing cytokines that mediate fibrosis or pain. In another uncontrolled study, IVIg reduced the number of cataplectic attacks in narcolepsy patients.

CONCLUSIONS

IVIg is effective in anti-GAD-positive patients with SPS. Whether it is also effective in other GAD-positive CNS disorders such as epilepsies, cerebellar degenerations or Batten's disease need to be studied in control trials. Emerging data suggest that IVIg, by suppressing proinflammatory cytokines, may exert a beneficial effect in patients with Alzheimer's disease, postpolio syndrome, chronic pain syndromes, fibrotic disorders and narcolepsy. Controlled studies are being planned or conducted to substantiate the benefit of IVIg in neurodegenerative disorders.

Intravenous immunoglobulin for post-polio syndrome: a randomised controlled trial

BACKGROUND

Survivors of poliomyelitis often develop increased or new symptoms decades after the acute infection, known as post-polio syndrome. Production of proinflammatory cytokines within the CNS indicates an underlying inflammatory process, accessible for immunomodulatory treatment. We did a multicentre, randomised, double-blind, placebo-controlled study of intravenous immunoglobulin in post-polio syndrome.

METHODS

142 patients at four university clinics were randomly assigned infusion of either 90 g in total of intravenous immunoglobulin (n=73) or placebo (n=69) during 3 consecutive days, repeated after 3 months. Seven patients were withdrawn from the study. Thus, 135 patients were assessed per protocol. Primary endpoints were muscle strength in a selected study muscle and quality of life as measured with the SF-36 questionnaire (SF-36 PCS). Secondary endpoints were 6-minute walk test (6MWT), timed up and go (TUG), muscle strength in muscles not chosen as the study muscle, physical activity scale of the elderly (PASE), visual analogue scale (VAS) for pain, multidimensional fatigue inventory (MFI-20), balance, and sleep quality. Outcome tests were done immediately before the first infusion and 3 months after the second infusion. This study is registered with , number NCT00160082.

FINDINGS

Compared with baseline, median muscle strength differed by 8.3% between patients receiving intravenous immunoglobulin and placebo, in favour of the treatment group (p=0.029). SF-36 PCS did not differ significantly between the groups after treatment (p=0.321). Differences in the subscale vitality score (p=0.042) and PASE (p=0.018) favoured the active treatment group. MFI-20, TUG, muscle strength in the muscles not chosen as the study muscle, 6MWT, balance, and sleep quality did not differ between groups. For the whole study population there was no significant change in pain, as determined by VAS. Nevertheless, patients who reported pain at the study start improved in the intervention group but not in the placebo group (p=0.037). Intravenous immunoglobulin was well tolerated.

INTERPRETATION

Intravenous immunoglobulin could be a supportive treatment option for subgroups of patients with post-polio syndrome. Further studies on responding subgroups, long-term effects, and dosing schedules are needed.

The Relation Between Walking Capacity and Clinical Correlates in Survivors of Chronic Spinal Poliomyelitis

OBJECTIVES

To examine (1) common clinical measures that may influence walking performance in the six-minute walk test (6MWT) in people with chronic poliomyelitis and (2) the test-retest reliability of the 6MWT distance, lower-extremity muscle strength, balance, and balance confidence on separate trials.

DESIGN

A prospective quasi-experimental study.

SETTING

University-based postpolio clinic.

PARTICIPANTS

Nineteen survivors of poliomyelitis (mean age, 62.2+/-1.9y; time since polio onset, 54.4+/-8.79y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

6MWT distance, rate-pressure product (RPP), Physiological Cost Index (PCI), ratings of perceived exertion (RPE), pain, fatigue, strength, standing balance, balance confidence, limb-length discrepancy, and lung function.

RESULTS

The 6MWT distance correlated with PCI, pretest pain, lower-extremity muscle strength, balance, balance confidence, corrected leg-length discrepancy, and lung function but not with RPP, RPE, posttest pain, or pretest and posttest fatigue. The PCI correlated with balance confidence and lung function. About 68% of the variance in 6MWT distance was accounted for by balance and pretest pain. The P value was set at .05.

CONCLUSIONS

With stringent standardization of the 6MWT applied to survivors of poliomyelitis (a neuromuscular condition with a musculoskeletal component), reproducibility was high; hence, test validity and interpretation were enhanced. The 6MWT distance was useful in elucidating the relation between impairment and a functional activity-namely, walking-in survivors of poliomyelitis.

Social stress alters the severity and onset of the chronic phase of Theiler's virus infection

Social stress alters the acute phase of Theiler's virus infection (TMEV), a model of multiple sclerosis. Stress applied prior to infection had deleterious disease outcomes, while stress applied concurrent with infection was protective. The current study examined multiple behavioral (motor impairment, open field activity) and immunological measures (IL-6, antibodies to virus and myelin proteins) in both the acute and chronic phases of TMEV. It was found that stress applied prior to infection exacerbated disease outcomes, while concurrent application was protective in both disease phases.

Fatigue of muscles weakened by death of motoneurons

Weakness is a characteristic of muscles influenced by the postpolio syndrome (PPS), amyotrophic lateral sclerosis (ALS), and spinal cord injury (SCI). The strength deficits relate to changes in muscle use and to the chronic denervation that can follow the spinal motoneuron death common to these disorders. PPS, ALS, and SCI also involve variable amounts of supraspinal neuron death, the effects of which on muscle weakness remains unclear. Nevertheless, weakness of muscle itself defines the functional consequences of these disorders. A weaker muscle requires an individual to work that muscle at higher than usual intensities relative to its maximal capacity, inducing progressive fatigue and an increased sense of effort. Little evidence is available to suggest that the fatigue commonly experienced by individuals with these disorders relates to an increase in the intrinsic fatigability of the muscle fibers. The only exception is when SCI induces chronic muscle paralysis. To reduce long-term functional deficits in these disorders, studies must identify the signaling pathways that influence neuron survival and determine the factors that encourage and limit sprouting of motor axons. This may ensure that a greater proportion of the fibers in each muscle remain innervated and available for use.

Recovery and prognosticators of paralysis in West Nile virus infection

Previous studies have demonstrated that lesions of the anterior horn motor neurons are the primary pathology in patients with paralysis due to West Nile virus (WNV) infection. To characterize recovery and identify prognostic factors for the recovery of paralysis, we investigated 11 patients with electrophysiology testing and muscle biopsy, and one with autopsy. We found that limb weakness was markedly asymmetric and differed between upper and lower extremities, suggesting focal or segmental involvement of the spinal cord anterior horn. This was supported by segmental depletion of spinal motor neurons at autopsy. Clinical recovery was variable during a 21-month follow-up period. To explain variability, we performed motor unit number estimation (MUNE) in six patients. MUNE values and strength were correlated in tested muscles. We also detected motor nerve terminal damages in muscle biopsies, suggesting another possible mechanism for transient weakness and variable recovery. We conclude that the type of pathological lesions may vary in paralytic WNV infection, and different degrees or combinations of motor neuron loss and motor nerve terminal changes may account for the observed degrees of weakness and recovery.