平山病患者的临床电生理及颈磁共振成像研究

Clinical, electromyographic and cervical magnetic resonance imaging features of Hirayama disease

目的研究平山病（HD）患者的临床特征、肌电生理及颈磁共振成像（MRI）特点。方法观察15例HD患者的特殊临床表现，检测双侧上肢远端及下肢常规肌电图及周围神经传导速度，行颈部自然位、过屈位及过伸位MRI扫描，观察低位颈髓有无萎缩及颈椎曲线情况。结果15例患者均为男性，青春期起病．病变均表现为上肢远端肌肉、骨间肌、鱼际肌萎缩和双手厥冷无力。肌电图检查示患者受累侧远端肌运动单位平均时限宽，多相波增多，波幅显著增高（巨大电位），主要位于C7、C8及T1节段。颈自然位MRI示9例患者低位颈髓萎缩，主要在C5、C6节段。所有患者过屈位时颈髓前移、变扁平，变扁节段以C6为主。结论HD主要发生在青春期，以男性多见，临床表现和肌电图检查提示局限于下位颈髓的前角病变，颈部自然位和过屈位MRI不同的特点可协助诊断。

Objective To investigate the clinical, electromyographic and cervical magnetic resonance imaging （MRI） characteristics of Hirayama disease. Methods Fifteen patients with Hirayama disease were observed for special clinical manifestations and underwent electromyographic examination of the bilateral distal upper limb muscles and peripheral nerve conduction velocity. MRI of the neck in neutral and fully flexed positions was perfbrmed to identify potential lower cervical cord atrophy and cervical curvature anomalies. Results All the 15 male patients had disease onset during puberty with asymmetric muscular atrophy and weakness of the hands and forearms. Concentric needle electromyography revealed prolonged duration and large amplitude of the motor unit potentials in the compromised distal limb muscles with also increased polyphasic potentials and poor recruitment, involving mainly the C7, C8 and T1 myotomes. In neutral neck position, MRI identified lower cervical cord atrophy in 9 patients, occurring mainly at C5, C6 levels; in fully flexed position, all patients showed forward displacement and flattening of the lower cervical cord, occurring mostly at C6 level. Conclusion Hirayama disease occurs mainly in puberty in young male patients, whose clinical features and electromyographic examination often indicate localized anterior horn anomalies in the lower cervical cord. MRI of the neck in neutral and fully flexed position can provide valuable assistance in the diagnosis of this disease.