平山病的电生理研究

An electrophysioiogical study of Hirayama disease

目的分析总结平山病神经电生理检查结果的特点，探讨电生理检查对平山病的诊断意义。方法对18例临床确诊为平山病的患者（男16例，女2例；年龄19～58岁，平均24．9岁；病史1～40年，平均5．2年；10例为单侧发病，3例双侧发病，5例疑似双侧发病）进行神经电生理检测。所有病例均检测：患侧正中神经、尺神经的运动传导速度（MCV）和感觉传导速度（SCV），以及小指展肌、拇短展肌、指总伸肌、肱桡肌、肱二头肌、胸锁乳突肌的肌电图；下肢一侧（与上肢患侧同侧）腓总神经MCV、SCV，以及胫前肌的肌电图。双侧或疑似双侧发病共8例患者检测对侧尺神经MCV、SCV，以及小指展肌、指总伸肌、肱桡肌肌电图。正中神经、尺神经MCV采用由远端至近端分段刺激，记录复合肌肉动作电位（CMAP），并判断是否存在神经传导阻滞。结果①18例患者正中神经、尺神经检测均无神经传导阻滞表现。②18例患者正中神经、尺神经SCV及感觉神经动作电位（SNAP）均无异常。③上肢MCV,减慢总阳性率为43．2％（19／44），不同神经阳性率由高至低依次为：患侧尺神经72．2％（13／18）、患侧正中神经33．3％（6／18）、对侧尺神经0（0／8）。④上肢CMAP波幅降低总阳性率为81．8％（36／44），不同神经阳性率由高至低依次为：患侧尺神经100．0％（18／18）、患侧正中神经77．8％（14／18）、对侧尺神经50．0％（4／8）。⑤18例患者腓总神经MCV、SCV及胫前肌的肌电图均无异常。⑥上肢肌电图检查：神经性损害表现总阳性率为47．0％（62／132），不同检测肌肉神经性损害阳性率由高至低依次为：患侧小指展肌100．0％（18／18）、患侧拇短展肌100．0％（18／18）、患侧指总伸肌88．9％（16／18）、对侧小指展肌62．5％（5／8）、对侧指总伸肌37．5％（3／8）、患侧肱桡肌5．6％（1／18）、患侧肱二头肌5．6％（1／18）；对侧肱桡肌以及患侧胸锁乳突肌的肌电图均未检出神经性损害表现。结论平山病神经电生理学特点为单侧上肢神经源性损害、或为单侧表现明显的双侧上肢神经源性损害；根据异常肌电图分布范围提示患侧C7～T1脊髓前角细胞损害，C6及C6以上节段少有累及。平山病的神经电生理学特点可为该病提供有助于定位诊断和鉴别诊断的依据。

[ Abstract] Objective To analyze the electrophysiological characteristics of Hirayama disease and explore their significance for its diagnosis. Methods Electrophysiological tests were performed on 18 patients who ful- filled the clinical criteria for Hirayama disease. Sixteen were males and 2 were females. The mean age was 24.9 years old （ 19-58 years） , and the mean case history was 5.2 years （ 1-40 years）. The Hirayama disease was clear- ly unilateral in 10 patients and bilateral in 3, with 5 cases suspected of being bilateral. Motor neuron conduction velocity （MCV） and sensory neuron conduction velocity （SCV） were measured in the median and ulnar nerves. Electromyograms （EMGs） of the abductor digiti minimi, abductor pollicis brevis, extensor digito^m communis, brachioradialis muscle, biceps brachii and sternocleidomastoid were recorded in all cases. The MCV and SCV of the common peroneal nerve and an EMG of the tibialis anterior muscle were examined in one leg. The MCV and SCV of the ulnar nerve and EMGs of the abductor digiti minimi, extensor digitorum communis and brachioradialis muscles were inspected on the contralateral sides of 8 cases, including the patients suspected of suffering bilateral Hirayama disease. The MCVs of the median and ulnar nerves were examined segmentally by stimulating the nerves distally as well as proximally, and recording the amplitude, duration and area of compound muscle action potentials （CMAP） and changes in wave form, then determining whether there was a nerve conduction block. Results （ 1 ） No conduction block was detected in any median nerve or ulnar nerve among the 18 cases. （2） All the SCVs and sensory nerve action potentials of the median and ulnar nerves were normal. （3） All the MCVs and SCVs of the common peroneal nerve and the EMGs of the anterior tibialis muscles were normal. （d） MCV slowing in the upper limbs accounted for 41.3% （19/44） of the examined nerves. The rates of MCV decrease were 72.2% （13/18） in the ulnar nerve on the affected sides, 33.3% （6/18） in the median nerve on the affected sides and 0% （0/8） in the ulnar nerve on the eontralateral sides. （5） Amplitude reduction in the CMAP in the upper limbs accounted for 81.8% （36/44） of the examined nerves. The rates of amplitude decrease were 100% （18/18） in the ulnar nerves of the affected sides, 77.8% （14/18） of median nerves on the affected side and 50% （4/8） of ulnar nerves on the contralateral side. （6） Upper limb EMGs revealed a rate of neurogenic damage of 47.0% （62/ 132 ）. The EMGs decreased in 100% （ 18/18 ） of the abductor digiti minimi and abductor pollieis brevis on the af- fected side, 88.9% （16/18） of extensor digitorum communis on the affected side, 62.5% （5/8） of the abductor digiti minimi on the contralateral side, 37.5% （3/8） of the extensor digitorum communis on the contralateral side, 5.6% （1/18） of the brachioradialis and biceps brachii muscles on the affected sides. There was no neurogenic damage of the contralateral brachioradialis muscle or the sternocleidomastoid on the affected side. Conclusions The electropbysiological features of Hirayama disease include unilateral or bilateral neurogenic damage in the upper limbs. According to the abnormal EMGs, spinal anterior horn cells on the affected sides were injured at C7-T1. C6 and above C6 were rarely involved. The electrophysiological characteristics of I-tirayama disease could provide a clear basis for localization and differentiation in Hirayama disease diagnosis.