MacKinnon Colum D, Gilley Emily A, Weis-McNulty Annette, Simuni Tanya
Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
Ann Neurol. 2005 Oct;58(4):516-24. doi: 10.1002/ana.20599.
Previous studies have used paired-pulse transcranial magnetic stimulation to show that short-interval intracortical inhibition (SICI) is reduced in patients with Parkinson's disease (PD). This study examined whether reduced SICI in PD is caused by an increase in the threshold of inhibitory pathways or a reduction in the threshold of excitatory pathways. Motor-evoked potentials were recorded from a hand muscle in 12 patients with PD (7 patients were tested off and on antiparkinsonian medications) and 12 control subjects. SICI was tested at seven conditioning stimulus intensities (CSIs; 40-100% of resting motor threshold) and at interstimulus intervals (ISIs) of 2, 3, and 4 milliseconds. No differences were found between groups in resting or active motor threshold, SICI threshold, or the extent of SICI at CSIs at or below 80% of resting motor threshold. Significant differences between groups were observed at CSIs of 90% and 100% with an ISI of 3 milliseconds. Antiparkinsonian medication had no effect on SICI. These findings show that the low threshold inhibitory pathways mediating SICI are normal in PD. The suppression of SICI observed at higher CSIs suggests that the threshold of intracortical facilitatory pathways is decreased in PD.
以往的研究使用配对脉冲经颅磁刺激来表明，帕金森病（PD）患者的短间隔皮质内抑制（SICI）降低。本研究调查了PD中SICI降低是由抑制性通路阈值升高还是兴奋性通路阈值降低所致。记录了12例PD患者（7例在服用和未服用抗帕金森病药物时接受测试）和12名对照受试者手部肌肉的运动诱发电位。在七种条件刺激强度（CSIs；静息运动阈值的40 - 100%）以及2、3和4毫秒的刺激间隔（ISIs）下测试SICI。在静息或主动运动阈值、SICI阈值或静息运动阈值80%及以下的CSIs时的SICI程度方面，两组之间未发现差异。在90%和100%的CSIs以及3毫秒的ISI时观察到两组之间存在显著差异。抗帕金森病药物对SICI无影响。这些发现表明，介导SICI的低阈值抑制性通路在PD中是正常的。在较高CSIs时观察到的SICI抑制表明，PD中皮质内易化通路的阈值降低。
