Case report of conventional electrodiagnosis of a subject with postpolio syndrome
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0975-2870.148850
In the past few years, many polio survivors have experienced late-onset neuromuscular symptoms such as fatigue, pain, new, and unusual muscular deficits and decreased functional abilities. Post polio syndrome (PPS) refers to a clinical disorder affecting polio survivors with sequel years after the initial polio attack. The purpose of the present study was to present the results of electrodiagnostic findings in muscle weakness encountered in PPS. Study was suggestive of ongoing axonal degeneration in Rt. Deltoid, biceps, and both soleus muscles with regeneration. Presence of new symptoms of weakness and fatigue in some muscles previously not affected by poliomyelitis and electrodiagnostic findings were suggestive of a diagnosis of PPS. Keywords: Conventional electromyography, nerve conduction velocity study, post-polio syndrome
In the past few years, many polio survivors have experienced late-onset neuromuscular symptoms such as fatigue, pain, new, and unusual muscular deficits and decreased functional abilities. [1] Post polio syndrome (PPS) refers to a clinical disorder affecting polio survivors with sequel years after the initial polio attack. The prevalence of PPS has been reported to be between 20% and 85% of people who have had poliomyelitis. [2] 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. India has the maximum number of polio survivors; so the purpose of this study is to present the results of electrodiagnostic findings encountered in PPS to increase awareness of PPS.
Written informed consent was obtained from the subject prior to performing the study. A 63-year-old retired bank officer came to the hospital with the complaints of post traumatic pain in left shoulder, weakness in right upper extremity and difficulties in activities of daily living (ADLs). He retired from work before 10 years and is currently managing accounting with partners. He has a history of poliomyelitis in bilateral lower extremities, but manages ambulation without use of assistive devices. He also manages to drive a two-wheeler without the need of any modifications or aids. He has a known history of diabetes and hypertension, controlled with regular oral medications. He is left hand dominant, doing most self-care activities with the same. On 21.05.2013, 8 months ago while at home, he gives an alleged history of slipping on a wet surface, falling against his back and sustaining injury on his left shoulder. He developed pain in the left shoulder joint with gradual restriction in all shoulder range of motions (ROM). After consulting his orthopedic doctor, he underwent investigations in the form of X-ray and magnetic resonance imaging (MRI) of left shoulder, which was suggestive of complete full thickness tear of supraspinatus along with tear in subscapularis. He then received physical therapy management of left shoulder, while continuing to manage his ADLs by compensating with the right upper extremity. Over the course of 2 weeks, he noticed weakness in right upper extremity and experienced difficulties accomplishing ADLs, particularly repeated activities. Bilateral upper extremity hand function remained unimpaired. Since then, he has been on regular physical therapy management for bilateral upper extremities. There has been minimal improvement in left shoulder pain and ROM, but no improvement in right upper extremity function. Furthermore, managing ADLs was getting difficult day-by-day with complaints of fatigue after few bouts of movements with the right upper extremity. He also had a complaint of right foot pain which is intermittent in nature. He has a history of backpain, which was relieved by medications and significant weight loss of about ten kilos. Over a period of 20 years, his walking capacity has also decreased with frequent rest periods required to cover small distances. Examination Passive ROM of right upper extremity was full and pain-free. Left shoulder abduction, flexion and rotations were restricted and painful. Deformities were present in bilateral lower extremities in the form of hammer toes, planovalgus feet, hyper-extension of left knee, and thoracolumbar scoliosis. Muscle power of upper extremity is shown in [Table 1]. Lower limb muscle power was fair to good, except tibialis anterior bilaterally, left quadriceps and left extensor hallucis longus, which were poor. Bilateral hand grips were strong. Sensory system was unaffected. Subject's sitting balance was good, whereas dynamic standing balance was fair to good.
Clinical Diagnosis Differential diagnosis in this case was brachial neuritis, rotator cuff injury, motor neuron disease, polyneuropathy, and cervical radiculopathy. Absence of sensory affection and absence of pain on examination ruled out brachial neuritis and cervical radiculopathy. Furthermore on examination, there was no neck pain and no provocative tests positive for cervical radiculopathy. Absence of pain and presence of full range of shoulder active movement ruled out rotator cuff injury. Absence of upper motor signs ruled out motor neuron disease. The criteria for PPS [3] according to Halstead are confirmed history of polio, partial or fairly complete neurological and functional recovery after the acute episode followed by a period of at least 15 years with neurological and functional stability with two or more of the following health problems occurring after the stable period: Extensive fatigue, muscle and/or joint pain, new weakness in muscles previously affected or unaffected, new muscle atrophy, functional loss and cold intolerance. Also no other medical explanation should be found. PPS is an exclusion diagnosis. Halstead revised these criteria in 1991 and added gradual or abrupt onset of new neurogenic weakness as a necessary criterion for PPS, with or without other co-existing symptoms. [4] Dalakas redefined and narrowed the use of PPS in 1995 with an additional criterion of neurological examination on electromyography (EMG) and/or MRI. [5] In the present case, the presence of polio with more than 15 years of neurological and functional stability, along with history of fatigue and new muscle weakness was suggestive of a diagnosis of PPS. To confirm PPS, EMG and nerve conduction velocity (NCV) study was performed. Electrodiagnosis Findings of NCV tests are shown in [Table 2].
Distal motor latencies bilateral median, ulnar, peroneal and left tibial nerves were within normal limits with normal compound motor action potential (CMAP) amplitude and motor nerve conduction velocity (MNCV). Proximal CMAP of left ulnar nerve was reduced because ideal position could not be assumed. Distal and proximal motor latencies right tibial nerve were prolonged with reduced CMAP amplitude and reduced MNCV. Distal sensory latencies bilateral median, ulnar, and sural nerves were within normal limits. Electromyography was performed using concentric needle for right infraspinatus, deltoid, biceps and bilateral soleus as shown in [Table 3]. Spontaneous activity in the form of fibrillation potentials were seen in right deltoid, biceps brachi and both soleus muscles. Motor unit action potentials having normal to long duration, normal to large amplitude and bi, tri and polyphasic in shape were seen in all tested muscles. Fair to good recruitment with incomplete interference pattern was seen in all tested muscles. The above findings are suggestive of new or continuous loss of neurons in right deltoid, biceps brachii and bilateral soleus muscles. The above findings rule out possibility of C5 nerve root radiculopathy or C5-6 brachial plexopathy as infraspinatus muscle EMG is normal. NCV studies also rule out possibility of polyneuropathy. The NCV findings are also suggestive of Right Tarsal tunnel syndrome
Study was suggestive of ongoing axonal degeneration in right deltoid, biceps, and bilateral soleus muscles with regeneration with new symptoms of weakness and fatigue. Some muscles were previously not affected by poliomyelitis, which is suggestive of post polio syndrome (PPS) according to the revised criteria. [4],[5]
Cashman et al [6] performed conventional EMG, Single fibre EMG (SFEMG) and muscle biopsy in a group of patients with well-defined PPS and compared them with a control group of polio survivors without new symptoms. They found no difference between both groups with regard to active ongoing denervation by electrophysiology and muscle biopsy. However, they found evidence of remote denervation, which correlated well with evidence of ongoing denervation. This might suggest that the usually over-extended motor units from old polio were more vulnerable to undergo terminal axonal degeneration in later life. Kimura [7] concluded that fibrillation potentials develop as motor axons degenerate. Re-innervation results in diminution of spontaneous discharges and appearance of motor unit potential of large amplitude and long duration. Weak muscles may only have few extremely large motor unit potentials. A prospective study of 24 patients with a history of paralytic poliomyelitis revealed evidence of widespread chronic partial denervation despite restricted clinical weakness. EMG showed substantially increased mean interference amplitude not only in weak muscles, but also in apparently unaffected muscles contralateral to the clinically involved spinal segments. NCV studies revealed normal velocities but reduced amplitude of the CMAP, approximately in proportion to the degree of muscle atrophy. Fibrillation potentials often of low amplitude indicating muscle fiber atrophy may persist for years. Wiechers and Hubbel [8] for example recorded fibrillation potentials 32 years after acute polio in a 61-year-old man without progressive weakness. An article by Trojan et al [9] describing electrodiagnostic studies-conventional EMG, SFEMG, and macro-EMG has provided information on the postpolio motor unit and on the possible etiology of some PPS 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 CMAP's on repetitive stimulation, and increased jitter and blocking on SFEMG. Progressive weakness and atrophy in PPS is probably due to a distal degeneration of postpolio 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 PPS symptoms, no specific electrodiagnostic test for the syndrome is currently available. Based on the findings of an increase in motor unit size over time (an indicator of neuronal loss) in the vastus lateralis and tibial anterior muscles compared with little or no change in the biceps brachii muscles, Sandberg and Stålberg [10] suggest that muscular overuse may be an important factor that accelerates the age-dependent motoneuron loss in polio survivors. The potential to overuse large, weight-bearing muscle groups in the lower extremities should be considered in patient management. In patients with large and few remaining motor units, special advice should be given regarding the reduction of excessive use of muscles (weight reduction, restriction of limb muscle exercise) and at a certain stage, in the use of ambulatory aids. To minimize symptoms of fatigue, short breaks in activity or a midday nap may be recommended. Management plans must be individualized and should focus on the fact that the patient with prior polio has fewer motoneurons than do healthy subjects. The cause of new symptoms in postpolio patients is still being debated. The main reason may be the ongoing loss of neurons over time, but other possibilities are being considered. One factor that may increase the rate of loss in strength, for whatever reason, is overuse of muscles. A limitation of the study was that conventional EMG was performed and not SFEMG.
The authors would like to thank Dr. Neeta Vyas (PT) and Dr. Nehal Shah (PT) for their constant support and guidance.
[Table 1], [Table 2], [Table 3]
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