Ugawa Y, Terao Y, Hanajima R, Sakai K, Furubayashi T, Machii K, Kanazawa I
Department of Neurology, Institute for Brain Research, School of Medicine, University of Tokyo, Japan.
Electroencephalogr Clin Neurophysiol. 1997 Sep;104(5):453-8. doi: 10.1016/s0168-5597(97)00051-8.
We studied 20 patients with ataxia caused by various disorders using magnetic stimulation over the cerebellum. Results were compared with normal values found for 12 normal volunteers. In normal subjects, a magnetic stimulus over the cerebellum reduced the size of responses evoked by magnetic cortical stimulation when it preceded cortical stimulus by 5, 6 and 7 ms. The grand average of the ratios of the areas of conditioned responses at intervals of 5, 6 and 7 ms to those of control responses was designated the average area ratio (5-7 ms). Suppression of motor cortical excitability was reduced or absent in patients with a lesion in the cerebellum or cerebellothalamocortical pathway, but was normal in patients with a lesion in the afferent pathway to the cerebellum. Normal suppression was observed in Fisher's syndrome. The average area ratio (5-7 ms) correlated well with the severity of ataxia in patients with degenerative late-onset ataxia. These results are consistent with those for electrical stimulation of the cerebellum reported previously. We conclude that magnetic stimulation over the cerebellum produces the same effect as electrical stimulation even in ataxic patients. This less painful method can be used clinically to clarify the pathomechanisms for ataxia. Two other clinical uses of this technique were that it revealed clinically undetectable cerebellar dysfunction in patients whose extrapyramidal signs masked cerebellar signs, and that the slow progression of ataxia could be followed quantitatively in patients with degenerative late-onset ataxia.
我们使用小脑磁刺激研究了20例由各种疾病引起共济失调的患者。将结果与12名正常志愿者的正常值进行比较。在正常受试者中，当小脑磁刺激在皮层刺激前5、6和7毫秒时，会减小皮层磁刺激诱发反应的大小。将5、6和7毫秒间隔时条件反应面积与对照反应面积的比率的总体平均值指定为平均面积比率（5 - 7毫秒）。小脑或小脑丘脑皮质通路有病变的患者，运动皮层兴奋性的抑制减弱或缺失，但小脑传入通路有病变的患者则正常。在Fisher综合征中观察到正常的抑制。平均面积比率（5 - 7毫秒）与迟发性退行性共济失调患者的共济失调严重程度密切相关。这些结果与先前报道的小脑电刺激结果一致。我们得出结论，即使在共济失调患者中，小脑磁刺激也能产生与电刺激相同的效果。这种疼痛较小的方法可在临床上用于阐明共济失调的发病机制。该技术的另外两个临床用途是，它揭示了锥体外系体征掩盖小脑体征患者临床上无法检测到的小脑功能障碍，并且可以对迟发性退行性共济失调患者共济失调的缓慢进展进行定量跟踪。
