目的　初步探讨膈肌运动诱发电位 (DMEP)在肌萎缩侧索硬化 (ALS)患者的应用及特点。方法　以表面电极在肋间隙处记录 37例ALS患者及 31例正常对照者经颅及经项磁刺激时产生的膈肌复合肌肉动作电位潜伏期和波幅 ,并计算中枢运动传导时间 (CMCT)。 2 2例ALS患者同时接受了用力肺活量百分比 (%FVC)测定。结果　ALS患者较对照者颈及皮层潜伏期延长 ,颈及皮层波幅对数降低 ,CMCT延长。皮层潜伏期、皮层波幅对数、CMCT均与锥体束受累相关 ;皮层潜伏期和CMCT与临床呼吸困难相关 ,颈潜伏期与 %FVC相关。结论　CMCT、颈及皮层潜伏期是DMEP参数中反映ALS患者呼吸功能障碍的敏感指标。CMCT反映ALS患者与呼吸功能相关的皮质脊髓束功能 ,CMCT与颈潜伏期结合有助于全面准确地揭示ALS患者呼吸受累的本质 Objective To investigate the application and characteristics of diaphragmatic motor evoked potentials (DMEP) in patients with amyotrophic lateral sclerosis (ALS). Methods The latency and amplitude of diaphragmatic muscle action potentials were recorded by transcranial and magnetic field stimulation in 37 ALS patients and 31 healthy controls at the intercostal space at the surface electrodes. The CMCT was calculated. Twenty-two patients with ALS received both forced vital capacity (% FVC) measurements. Results Compared with control subjects, the latency of neck and cortex in ALS patients was prolonged, the logarithm of the amplitude of cervical and cortex decreased, and the CMCT prolonged. Cortical latency, cortical amplitude logarithm, CMCT were associated with pyramidal tract involvement; cortical latency and CMCT were associated with clinical dyspnea, and cervical latency correlated with% FVC. Conclusion The CMCT, cervical and cortical latency are sensitive indicators of DMEP parameters reflecting respiratory dysfunction in patients with ALS. CMCT reflects respiratory function related ALS patients with corticospinal tract function, CMCT and neck incubation period helps to fully and accurately reveal the nature of respiratory involvement in patients with ALS