Department of Neurology and Brain Research Institute, Yonsei University College of Medicine, Seoul, South Korea.
Clin Neurophysiol. 2010 Jul;121(7):1138-41. doi: 10.1016/j.clinph.2010.02.001. Epub 2010 Mar 3.
Paroxysmal kinesigenic dyskinesia (PKD) is characterized by recurrent attacks of dyskinesia, in which movement of one body part produces involuntary movements of other body parts. Surround inhibition (SI), a mechanism for suppression of unwanted movements, could be deficient in these patients. To test this idea, we performed a transcranial magnetic stimulation (TMS) study in drug-naive patients with PKD.
TMS was set to be triggered by self-initiated flexion of the index finger at different intervals. Average motor evoked potential (MEP) amplitudes obtained from self-triggered TMS were normalized to average MEPs of the control TMS at rest. Normalized MEP amplitudes of the patients' self-triggered TMS sessions at different intervals were compared to those of the controls.
During index finger flexion, MEP amplitudes from the little finger muscle were unchanged in both the patients and normal subjects, however, post-movement MEP enhancement observed in the normal subjects was absent in patients with PKD. These results suggest that the functional operation of SI is itself preserved, but that post-movement excitation of surrounding muscles is deficient in PKD.
This finding may represent that the operation of SI is extended to the post-movement period, perhaps as a compensatory mechanism for preventing unwanted movement in surrounding muscles.
While many types of impaired inhibition have been described previously in PKD, this is the first possible example of increased inhibition.
阵发性运动诱发性运动障碍（PKD）的特征是反复出现运动障碍，其中身体某一部分的运动导致身体其他部位的不自主运动。周围抑制（SI）是抑制不必要运动的一种机制，在这些患者中可能存在缺陷。为了验证这一观点，我们对未经药物治疗的 PKD 患者进行了经颅磁刺激（TMS）研究。
TMS 设置为在不同时间间隔内通过自我触发食指弯曲来触发。从自我触发的 TMS 中获得的平均运动诱发电位（MEP）幅度与休息时的对照 TMS 的平均 MEP 幅度进行归一化。将患者在不同时间间隔的自我触发 TMS 会话的归一化 MEP 幅度与对照组进行比较。
在食指弯曲期间，小指肌肉的 MEP 幅度在患者和正常受试者中均保持不变，然而，在正常受试者中观察到的运动后 MEP 增强在 PKD 患者中不存在。这些结果表明，SI 的功能操作本身是保留的，但 PKD 中周围肌肉的运动后兴奋是不足的。
这一发现可能表明 SI 的操作扩展到运动后时期，这可能是防止周围肌肉不必要运动的一种补偿机制。
虽然以前在 PKD 中已经描述了许多类型的抑制受损，但这是首次可能存在增加抑制的例子。
