OBJECTIVE Dystonia is associated with reduced intracortical inhibition as measured by the cortical silent period (cSP); however, this may be due to abnormal cSP threshold or input-output properties. This study evaluated cSP recruitment properties in people with cervical dystonia (CD). METHODS Bilateral electromyographic recordings were collected in the upper trapezius muscle in response to transcranial magnetic stimulation of the left and right primary motor cortex in a group with CD (n = 19) and controls (n = 21). cSP threshold, cSP input-output properties at stimulation intensities from 1 to 1.4x the cSP threshold, ipsilateral silent period duration (iSP) and timing and magnitude of the contralateral and ipsilateral motor evoked potential (MEP) were assessed. RESULTS The cSP threshold, input-output properties, and contralateral MEP magnitude were not significantly different between groups (all p > 0.07). Hemispheric symmetry was present in the control group while the CD group had reduced iSP (p < 0.01) and a trend for reduced ipsilateral MEP response (p = 0.053) in the left hemisphere. CONCLUSIONS Recruitment properties of intracortical inhibition are similar between control and CD groups. Transcallosal inhibition is asymmetric between hemispheres in people with CD. SIGNIFICANCE Evidence of normative intracortical inhibition recruitment properties challenge the commonly held view that cortical inhibition is reduced in dystonia.

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颈肌张力障碍正常皮质内抑制性募集特性的证据

目的 肌张力障碍与通过皮质静默期 (cSP) 测量的皮质内抑制降低有关；然而，这可能是由于异常的 cSP 阈值或输入输出属性。本研究评估了颈肌张力障碍 (CD) 患者的 cSP 募集特性。方法 在 CD 组 (n = 19) 和对照组 (n = 21) 的左右初级运动皮层经颅磁刺激后，在斜方肌上部收集双侧肌电图记录。评估了 cSP 阈值、刺激强度为 cSP 阈值 1 到 1.4 倍时的 cSP 输入输出特性、同侧静默期持续时间 (iSP) 以及对侧和同侧运动诱发电位 (MEP) 的时间和幅度。结果 cSP 阈值、输入输出特性、和对侧 MEP 大小在组间没有显着差异（所有 p > 0.07）。对照组存在半球对称性，而 CD 组的 iSP 降低（p < 0.01），并且左半球同侧 MEP 反应降低（p = 0.053）。结论 皮质内抑制的募集特性在对照组和 CD 组之间相似。CD 患者大脑半球之间的经胼胝体抑制是不对称的。意义 皮质内抑制募集特性的规范性证据挑战了普遍认为的皮质抑制在肌张力障碍中减少的观点。053）在左半球。结论 皮质内抑制的募集特性在对照组和 CD 组之间相似。CD 患者大脑半球之间的经胼胝体抑制是不对称的。意义 皮质内抑制募集特性的规范性证据挑战了普遍认为的皮质抑制在肌张力障碍中减少的观点。053）在左半球。结论 皮质内抑制的募集特性在对照组和 CD 组之间相似。CD 患者大脑半球之间的经胼胝体抑制是不对称的。意义 皮质内抑制募集特性的规范性证据挑战了普遍认为的皮质抑制在肌张力障碍中减少的观点。