Postpolio syndrome: unanswered questions regarding cause, course, risk factors, and therapies

Describing post-polio syndrome

INTRODUCTION

Patients presenting sequelae of poliomyelitis may present new symptoms, known as post-polio syndrome (PPS).

OBJECTIVE

To identify the clinical and functional profile and epidemiological characteristics of patients presenting PPS.

PATIENTS AND METHODS

We performed a retrospective study of 400 patients with poliomyelitis attended at the Institut Guttmann outpatient clinic, of whom 310 were diagnosed with PPS. We describe patients' epidemiological, clinical, and electromyographic variables and analyse the relationships between age of poliomyelitis onset and severity of the disease, and between sex, age of PPS onset, and the frequency of symptoms.

RESULTS

PPS was more frequent in women (57.7%). The mean age at symptom onset was 52.4 years, and was earlier in women. Age at primary infection >2 years was not related to greater poliomyelitis severity. The frequency of symptoms was: pain in 85% of patients, loss of strength in 40%, fatigue in 65.5%, tiredness in 57.8%, cold intolerance in 20.2%, dysphagia in 11.7%, cognitive complaints in 9%, and depressive symptoms in 31.5%. Fatigue, tiredness, depression, and cognitive complaints were significantly more frequent in women. Fifty-nine percent of patients presented electromyographic findings suggestive of PPS.

CONCLUSIONS

While the symptoms observed in our sample are similar to those reported in the literature, the frequencies observed are not. We believe that patients' clinical profile may be very diverse, giving more weight to such objective parameters as worsening of symptoms or appearance of weakness; analysis of biomarkers may bring us closer to an accurate diagnosis.

Poliomyelitis

Poliomyelitis, often termed "polio," is an acute infectious disease caused by an enterovirus which damages the anterior horn cells of the spinal cord and brainstem. Progress to lower motor neurone cell death leads to disruption of motor units and subsequent muscle weakness or complete paralysis. Although the virus is mostly eradicated from the Western world, postpolio decline is prevalent among people aged 60 years and over. It is characterized primarily by fatigability and muscle weakness, but pain is also common. Reductions in lower-limb muscle strength, voluntary drive, and endurance are likely to contribute to the impaired balance control, slow gait, and dysfunctional lower-limb kinematics reported in polio survivors. Given these significant risk factors, polio survivors fall up to four times more often than their age-matched healthy peers. Interventions to improve function, reduce disability, and prevent falls in polio survivors are therefore clinically relevant but studies are lacking, limiting the evidence base. Balance training, cognitive behavioral therapy, and orthoses prescription might be recommended. Muscle-strengthening programs should be carefully designed and delivered due to their potential detrimental effects related to excessive use and potential dysfunction of motor neurones and their axons.

Struggling to be part of Swedish society: Strategies used by immigrants with late effects of polio

OBJECTIVE

To explore and describe strategies in daily occupations among immigrants with late effects of polio.

METHOD

The strategies were explored by interviews with 12 immigrants from Eastern Africa with late effects of polio. Sampling and data analysis was carried out according to grounded theory.

RESULTS

The participants struggled for occupational participation and normality in an effort to participate in, and be part of, society. The study identified 14 strategies used by the immigrants in their daily occupations. The strategies can be presented in the following four categories: managing physical capacity; promoting occupational performance; strategies for gaining respect; and preparing the ground for one's existence. The participants struggled to find a balance between physical capacity and meaningful occupations, conception of their own and others' norms and values, and living conditions in Swedish society. The strategies were related to the participants' will to manage daily occupations, maintain social relationships, and be part of society.

CONCLUSIONS

The strategies revealed that the participants strive to participate in occupations and society. This study reinforces the importance of occupation for immigrants with disability. The results highlight the need for adequate health care and rehabilitation but should also alert other social institutions.

Treatment for postpolio syndrome

BACKGROUND

Postpolio syndrome (PPS) may affect survivors of paralytic poliomyelitis and is characterised by a complex of neuromuscular symptoms leading to a decline in physical functioning. The effectiveness of pharmacological treatment and rehabilitation management in PPS is not yet established. This is an update of a review first published in 2011.

OBJECTIVES

To systematically review the evidence from randomised and quasi-randomised controlled trials for the effect of any pharmacological or non-pharmacological treatment for PPS compared to placebo, usual care or no treatment. 

SEARCH METHODS

We searched the following databases on 21 July 2014: Cochrane Neuromuscular Disease Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO and CINAHL Plus. We also checked reference lists of all relevant articles, searched the Database of Abstracts of Reviews of Effects (DARE), the Health Technology Assessment (HTA) Database and trial registers and contacted investigators known to be involved in research in this area.

SELECTION CRITERIA

Randomised and quasi-randomised trials of any form of pharmacological or non-pharmacological treatment for people with PPS. The primary outcome was self perceived activity limitations and secondary outcomes were muscle strength, muscle endurance, fatigue, pain and adverse events.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We included 10 pharmacological (modafinil, intravenous immunoglobulin (IVIg), pyridostigmine, lamotrigine, amantadine, prednisone) and three non-pharmacological (muscle strengthening, rehabilitation in a warm climate (that is temperature ± 25°C, dry and sunny) and a cold climate (that is temperature ± 0°C, rainy or snowy), static magnetic fields) studies with a total of 675 participants with PPS in this review. None of the included studies were completely free from any risk of bias, the most prevalent risk of bias being lack of blinding.There was moderate- and low-quality evidence that IVIg has no beneficial effect on activity limitations in the short term and long term, respectively, and inconsistency in the evidence for effectiveness on muscle strength. IVIg caused minor adverse events in a substantial proportion of the participants. Results of one trial provided very low-quality evidence that lamotrigine might be effective in reducing pain and fatigue, resulting in fewer activity limitations without generating adverse events. Data from two single trials suggested that muscle strengthening of thumb muscles (very low-quality evidence) and static magnetic fields (moderate-quality evidence) are safe and beneficial for improving muscle strength and pain, respectively, with unknown effects on activity limitations. Finally, there was evidence varying from very low quality to high quality that modafinil, pyridostigmine, amantadine, prednisone and rehabilitation in a warm or cold climate are not beneficial in PPS.

AUTHORS' CONCLUSIONS

Due to insufficient good-quality data and lack of randomised studies, it was impossible to draw definite conclusions about the effectiveness of interventions for PPS. Results indicated that IVIg, lamotrigine, muscle strengthening exercises and static magnetic fields may be beneficial but need further investigation to clarify whether any real and meaningful effect exists.

Human spinal cord injury: motor unit properties and behaviour

Spinal cord injury (SCI) results in widespread variation in muscle function. Review of motor unit data shows that changes in the amount and balance of excitatory and inhibitory inputs after SCI alter management of motoneurons. Not only are units recruited up to higher than usual relative forces when SCI leaves few units under voluntary control, the force contribution from recruitment increases due to elevation of twitch/tetanic force ratios. Force gradation and precision are also coarser with reduced unit numbers. Maximal unit firing rates are low in hand muscles, limiting voluntary strength, but are low, normal or high in limb muscles. Unit firing rates during spasms can exceed voluntary rates, emphasizing that deficits in descending drive limit force production. SCI also changes muscle properties. Motor unit weakness and fatigability seem universal across muscles and species, increasing the muscle weakness that arises from paralysis of units, motoneuron death and sensory impairment. Motor axon conduction velocity decreases after human SCI. Muscle contractile speed is also reduced, which lowers the stimulation frequencies needed to grade force when paralysed muscles are activated with patterned electrical stimulation. This slowing does not necessarily occur in hind limb muscles after cord transection in cats and rats. The nature, duration and level of SCI underlie some of these species differences, as do variations in muscle function, daily usage, tract control and fibre-type composition. Exploring this diversity is important to promote recovery of the hand, bowel, bladder and locomotor function most wanted by people with SCI.

Treatment for postpolio syndrome

BACKGROUND

Postpolio syndrome (PPS) may affect survivors of paralytic poliomyelitis and is characterised by a complex of neuromuscular symptoms leading to a decline in physical functioning. The effectiveness of pharmacological treatment and rehabilitation management in PPS is not yet established.

OBJECTIVES

To review systematically the effects of any treatment for PPS compared to placebo, usual care or no treatment.  

SEARCH STRATEGY

We searched the following databases on 1 October 2010: Cochrane Neuromuscular Disease Group Specialized Register, the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PsycINFO and CINAHL Plus from inception to September 2010.

SELECTION CRITERIA

Randomised and quasi-randomised trials of any form of pharmacological or non-pharmacological treatment for people with PPS. The primary outcome was self-perceived activity limitations and secondary outcomes were muscle strength, muscle endurance, fatigue, pain and adverse events.

DATA COLLECTION AND ANALYSIS

Two authors independently selected eligible studies, assessed risk of bias and extracted data.

MAIN RESULTS

Nine pharmacological (modafinil, intravenous immunoglobulin, pyridostigmine, lamotrigine, amantadine, prednisone) and three non-pharmacological (muscle strengthening, rehabilitation in a warm climate (i.e. temperature ± 25°C, dry and sunny) and a cold climate (i.e. temperature ± 0°C, rainy or snowy), static magnetic fields) studies were included in this review. None of the included studies was completely free from any risk of bias and the most prevalent risk of bias was lack of blinding.There is moderate quality evidence that intravenous immunoglobulin has no beneficial effect on activity limitations and there is inconsistency in the evidence for effectiveness on muscle strength and pain. Results of one trial provide very low quality evidence that lamotrigine might be effective in reducing pain and fatigue, resulting in fewer activity limitations. Data from two single trials suggest that muscle strengthening of thumb muscles (very low quality evidence) and static magnetic fields (moderate quality evidence) are beneficial for improving muscle strength and pain, respectively, with unknown effects on activity limitations. Finally, there is evidence varying from very low quality to high quality that modafinil, pyridostigmine, amantadine, prednisone and rehabilitation in a warm or cold climate are not beneficial in PPS.

AUTHORS' CONCLUSIONS

Due to insufficient good quality data and lack of randomised studies it is impossible to draw definite conclusions on the effectiveness of interventions for PPS. Results indicate that IVIG, lamotrigine, muscle strengthening exercises and static magnetic fields may be beneficial but need further investigation.