Department of Neurology, Division of Neuroscience, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Mov Disord. 2011 Mar;26(4):685-90. doi: 10.1002/mds.23539. Epub 2011 Feb 16.
Abnormally enhanced cortical rhythmic activities have been reported in patients with cortical myoclonus. We recently reported a new triad-conditioning transcranial magnetic stimulation (TMS) method to detect the intrinsic rhythms of the primary motor cortex (M1). Triad-conditioning TMS revealed a 40-Hz intrinsic rhythm of M1 in normal subjects. In this investigation, we study the motor cortical facilitation induced by rhythmic triple TMS pulses (triad-conditioning TMS) in patients with cortical myoclonus.
Subjects were 7 patients with cortical myoclonus (28-74 years old) and 13 healthy volunteers (30-71 years old). Three conditioning stimuli over M1 at the intensity of 110% active motor threshold preceded the test TMS at various interstimulus intervals corresponding to 10-200 Hz. The resulting amplitudes of conditioned motor evoked potentials recorded from the contralateral hand muscle were compared with those evoked by the test stimulus alone.
The facilitation at 25 ms (40 Hz) observed in normal subjects was absent in patients with cortical myoclonus. Instead, triad-conditioning TMS induced facilitation at a 40 ms interval (25 Hz) in cortical myoclonus.
This change in the timing of facilitation may be explained by a shift of the most preferential intrinsic rhythm of M1, or by some dysfunction in the interneuronal network in cortical myoclonus.
皮质肌阵挛患者的皮质节律活动异常增强。我们最近报道了一种新的三联条件刺激经颅磁刺激（TMS）方法来检测初级运动皮层（M1）的固有节律。三联条件刺激 TMS 在正常受试者中揭示了 M1 的 40-Hz 固有节律。在这项研究中，我们研究了皮质肌阵挛患者中由节律性三重 TMS 脉冲（三联条件刺激 TMS）诱导的运动皮层易化。
受试者为 7 例皮质肌阵挛患者（28-74 岁）和 13 名健康志愿者（30-71 岁）。在各种刺激间隔（对应于 10-200 Hz）下，用强度为 110%主动运动阈值的 3 个刺激在 M1 上进行预处理，然后用测试 TMS 进行刺激。从对侧手部肌肉记录的条件运动诱发电位的幅度与仅由测试刺激引起的幅度进行比较。
在正常受试者中观察到的 25ms（40Hz）的易化在皮质肌阵挛患者中不存在。相反，在皮质肌阵挛中，三联条件刺激 TMS 在 40ms 间隔（25Hz）诱导易化。
这种易化时间的变化可能是由 M1 的最优先固有节律的移位或皮质肌阵挛中中间神经元网络的某些功能障碍引起的。
