Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
Hotchkiss Brain Institute, Calgary, AB, Canada.
J Clin Neurophysiol. 2023 May 1;40(4):293-300. doi: 10.1097/WNP.0000000000000884. Epub 2021 Jul 27.
Cerebellar connectivity is thought to be abnormal in cervical dystonia (CD) and other dystonia subtypes, based on evidence from imaging studies and animal work. The authors investigated whether transcranial magnetic stimulation-induced cerebellar brain inhibition (CBI), a measure of cerebellar efficiency at inhibiting motor outflow, is abnormal in patients with CD and/or is associated with clinical features of CD. Because of methodological heterogeneity in CBI reporting, the authors deployed additional controls to reduce potential sources of variability in this study.
Cerebellar brain inhibition was applied in 20 CD patients and 14 healthy control subjects. Cerebellar brain inhibition consisted of a cerebellar conditioning stimulus delivered at four different interstimulus intervals (ISIs) before a test stimulus delivered to hand muscle representation in the motor cortex. The average ratio of conditioned to unconditioned motor evoked potential was computed for each ISI. Cervical dystonia clinical severity was measured using the Toronto Western Spasmodic Torticollis Rating Scale. Control experiments involved neuronavigated transcranial magnetic stimulation, neck postural control in patients, and careful screening for noncerebellar pathway inhibition via cervicomedullary evoked potentials.
There was no difference between CBI measured in healthy control subjects and CD patients at any of the four ISIs; however, CBI efficiency was significantly correlated with worsening CD clinical severity at the 5 ms ISI.
Cerebellar brain inhibition is a variable measure in both healthy control subjects and CD patients; much of this variability may be attributed to experimental methodology. Yet, CD severity is significantly associated with reduced CBI at the 5 ms ISI, suggestive of cerebello-thalamo-cortical tract dysfunction in this disorder.
基于影像学研究和动物研究的证据，小脑连接被认为在颈椎病（CD）和其他肌张力障碍亚型中异常。作者研究了经颅磁刺激诱导的小脑脑抑制（CBI）是否异常，CBI 是衡量小脑抑制运动输出效率的一种方法，以及它是否与 CD 的临床特征相关。由于 CBI 报告的方法学存在异质性，作者增加了额外的对照来减少本研究中潜在的变异性来源。
20 例 CD 患者和 14 例健康对照接受了小脑脑抑制测试。小脑脑抑制由小脑刺激在运动皮层手部肌肉代表区的测试刺激之前在四个不同的刺激间隔（ISI）给予。对于每个 ISI，计算了条件化与未条件化运动诱发电位的平均比值。颈椎病严重程度使用多伦多西部痉挛性斜颈评定量表进行测量。对照实验包括神经导航经颅磁刺激、患者颈部姿势控制以及通过颈髓诱发电位仔细筛查非小脑通路抑制。
在四个 ISI 中的任何一个，健康对照组和 CD 患者的 CBI 测量值均无差异；然而，CBI 效率与 5ms ISI 时 CD 临床严重程度的恶化显著相关。
小脑脑抑制在健康对照组和 CD 患者中都是一个可变的测量指标；这种变异性的大部分可能归因于实验方法。然而，CD 严重程度与 5ms ISI 时的 CBI 降低显著相关，提示在这种疾病中存在小脑-丘脑-皮质束功能障碍。
