Jubelt B, Cashman N R
Les Turner Amyotrophic Lateral Sclerosis Research Laboratory, Northwestern University Medical School, Chicago, Illinois.
Crit Rev Neurobiol. 1987;3(3):199-220.
Patients with late effects of poliomyelitis, i.e., 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.
患有小儿麻痹后遗症（即PPS）的患者正越来越多地被普通内科医生、神经科医生和骨科医生诊治。自20世纪40年代和50年代小儿麻痹症大流行以来，已过了出现晚期表现的适当时间间隔。小儿麻痹后遗症的神经学表现主要包括新出现的肌无力、萎缩、肌肉疼痛和肌束震颤。幸运的是，肌无力呈非常缓慢的进行性。异常的实验室检查包括常规肌电图，显示慢性失神经支配；单纤维肌电图，显示纤维密度增加、颤抖增加和阻滞；肌肉活检在某些系列中最常显示慢性失神经支配的纤维类型分组以及小的孤立角形（或成角）纤维和群组萎缩，两者均提示存在活动性失神经支配。不幸的是，肌电图和肌肉活检研究都缺乏特异性，因为它们似乎无法区分既往患小儿麻痹症的无症状患者和有症状（新出现肌无力、PPMA）患者。虽然PPMA的病因尚不清楚，但电生理（单纤维肌电图）和肌肉活检研究表明，该过程涉及再支配运动单位的轴突终末的丧失或脱失。轴突终末脱失可能是由于胞体、轴突或终末本身功能障碍。目前尚不清楚运动神经元耗竭、持续性病毒感染或免疫介导机制是否在晚期肌无力的发病机制中起作用，这需要进一步研究。目前的治疗是支持性的。一个主要争议涉及强化锻炼在这些患者中的作用，因为实验动物研究表明，失神经支配肌肉的过度运动会导致肌无力加重。显然，对PPS和PPMA有更好的了解将有助于更有效地处理这些患者的问题，也可能为其他运动神经元和神经肌肉接头疾病提供见解。
