青年上肢远端肌萎缩症的临床及电生理特点

Electrophysiological characteristics of juvenile muscular atrophy of distal upper extremity （ Hirayama＇s disease）

目的 通过回顾性分析青年上肢远端肌萎缩症的临床和电生理检测结果,探讨该病的神经电生理特点.方法 分析77例青年上肢远端肌萎缩症患者正中神经和尺神经的运动和感觉神经传导、F波潜伏期及响应率,并分析针极肌电图中上肢肌受累情况.结果 在77例青年上肢远端肌萎缩症患者中,男74例,女3例;平均发病年龄（17.7±2.6）岁,平均病程（28.2±25.7）个月;57例患者以单侧上肢受累为主诉.尺神经复合肌肉动作电位（CMAP）波幅降低最多见;正中神经和尺神经F波响应率降低;感觉神经传导速度和感觉神经动作电位（SNAP）波幅均在正常范围内.针极肌电图表现为慢性神经源性改变为主,部分呈活动性改变.其中仅10例发现单侧上肢肌异常,67例均表现为双上肢肌损害.77例患者均有颈7～胸1节段的神经源性损害,部分患者伴有不同程度的颈5、6节段损害表现.无一例见颈1～颈4及其他节段支配肌的神经源性改变.结论 青年上肢远端肌萎缩症神经传导检查突出表现为尺神经CMAP波幅降低,尺神经和正中神经F波响应率降低.针极肌电图表现为双侧颈7、8与胸1节段支配肌呈慢性神经源性损害,可伴有颈5、6节段支配肌受累.

Objective The purpose of this study was to retrospectively evaluate the electrophysiological characteristics of Hirayama disease. Methods Electrophysiological records of 77 patients with a diagnosis of Hirayama disease were reviewed. We analyzed the amplitude of compound muscle action potential （CMAP） and sensory nerve action potential （SNAP） as well as the F wave latency and frequency of median and ulnar nerves. We also evaluated the changes of needle electromyography. Results Of the 77 patients, 74 were male and 3 female. Mean age of onset was （ 17.7 ± 2.6 ） years and mean disease duration （28.2 ± 25.7 ） months. 57 of the 77 patients showed clinical presentation of unilateral involvement. Reduced ulnar CMAP amplitude was found prodominantly. Abnormal F wave frequency was found in the majority of the patients in both median and ulnar nerves and there was also correlation between F wave frequency and amplitude of CMAP. Sensory conduction studies were normal. In the needle EMG, neurogenic changes were found in both upper limbs in 67 cases and the remaining 10 patients were unilateral involved. Denervation was found in the C7-T1 myotomes in all of the 77 patients. Among them, 15 also showed C5, C6 involvement with different extent. Conclusion In this study, the most obvious electrophysiological abnormality was reduced F wave frequency in both median and ulnar nerves followed by reduced ulnar CMAP amplitude. Although most patients showed unilateral involvement clinically,needle EMG found 87% had bilateral neurogenic changes. Although C7, C8, T1 myotomes were mainly damaged in Hirayama disease, C5,C6 was also involved in around 1/5 of the patients.