Pouget J, Trefouret S, Attarian S
Department of Neurology and Neuromuscular Diseases, University Hospital La Timone, Marseille, France.
Amyotroph Lateral Scler Other Motor Neuron Disord. 2000 Jun;1 Suppl 2:S45-9. doi: 10.1080/14660820052415817.
Owing to the low sensitivity of clinical signs in assessing upper motor neuron (UMN) involvement in ALS, there is a need for investigative tools capable of detecting abnormal function of the pyramidal tract. Transcranial magnetic stimulation (TMS) may contribute to the diagnosis by reflecting a UMN dysfunction that is not clinically detectable. Several parameters for the motor responses to TMS can be evaluated with different levels of significance in healthy subjects compared with ALS patients. The central motor conduction time, however, is not sensitive in detecting subclinical UMN defects in individual ALS patients. The amplitude of the motor evoked potential (MEP), expressed as the percentage of the maximum wave, also has a low sensitivity. In some cases, the corticomotor threshold is decreased early in the disease course as a result of corticomotor neuron hyperexcitability induced by glutamate. Later, the threshold increases, indicating a loss of UMN. In our experience, a decreased silent period duration appears to be the most sensitive parameter when using motor TMS in ALS. TMS is also a sensitive technique for investigating the corticobulbar tract, which is difficult to study by other methods. TMS is a widely available, painless and safe technique with a good sensitivity that can visualize both corticospinal and corticobulbar tract abnormalities. The sensitivity can be improved further by taking into account the several MEP parameters, including latency and cortical silent period decreased duration.
由于临床体征在评估肌萎缩侧索硬化症（ALS）中是否存在上运动神经元（UMN）受累时敏感性较低，因此需要能够检测锥体束功能异常的检查工具。经颅磁刺激（TMS）通过反映临床上无法检测到的UMN功能障碍，可能有助于诊断。与ALS患者相比，在健康受试者中，可以对TMS运动反应的几个参数进行不同显著水平的评估。然而，中枢运动传导时间在检测个体ALS患者的亚临床UMN缺陷方面并不敏感。运动诱发电位（MEP）的幅度，以最大波的百分比表示，其敏感性也较低。在某些情况下，由于谷氨酸诱导的皮质运动神经元兴奋性过高，皮质运动阈值在疾病早期会降低。后来，阈值升高，表明UMN丧失。根据我们的经验，在ALS中使用运动TMS时，静息期持续时间缩短似乎是最敏感的参数。TMS也是一种用于研究皮质延髓束的敏感技术，而皮质延髓束很难通过其他方法进行研究。TMS是一种广泛可用、无痛且安全的技术，具有良好的敏感性，能够显示皮质脊髓束和皮质延髓束的异常。通过考虑包括潜伏期和皮质静息期持续时间缩短在内的几个MEP参数，敏感性可以进一步提高。
