Smell and Taste Center, Department of Otorhinolaryngology: Head and Neck Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Arch Med Res. 2013 Apr;44(3):221-8. doi: 10.1016/j.arcmed.2013.03.003. Epub 2013 Mar 20.
The motor-evoked potential (MEP) induced by transcranial magnetic stimulation (TMS), its recruitment and the conditioning effects of weak stimuli in Parkinson's disease (PD) have shown contradictory results. The aim of this study is to definitively establish the influences of PD on the TMS-evoked MEP.
We investigated resting and active motor thresholds, resting and active recruitment curves, and short interval intracortical inhibition (ICI) and facilitation (ICF) in 39 PD patients and 40 age-matched healthy controls. The Unified Parkinson's Disease Rating Scale (UPDRS) motor score was used as a clinical measure.
MEPs to single pulses were slightly, but significantly, larger in the PD patients at rest, but increased much less than controls with voluntary muscle activation. PD patients also showed clearly and consistently less ICI and ICF by the conditioning pulse. Both ICI and ICF correlated with MEP threshold in healthy subjects, but not in PD patients. None of the TMS measures correlated with the UPDRS.
This study strongly supports the view that PD-related MEPs reflect a disturbed signal-noise ratio of pyramidal neuron responses. Such disturbance may be due to a complex combination of altered presynaptic and surround inhibition that results in unbalanced excitatory/inhibitory input at the brain motor cortex level.
经颅磁刺激（TMS）诱导的运动诱发电位（MEP）、其募集以及帕金森病（PD）中弱刺激的条件作用显示出相互矛盾的结果。本研究的目的是明确确定 PD 对 TMS 诱发的 MEP 的影响。
我们研究了 39 例 PD 患者和 40 例年龄匹配的健康对照者的静息和活动运动阈值、静息和活动募集曲线以及短程皮质内抑制（ICI）和易化（ICF）。使用统一帕金森病评定量表（UPDRS）运动评分作为临床测量。
与健康对照组相比，PD 患者在静息状态下的单脉冲 MEP 略大，但差异具有统计学意义，但在自愿肌肉激活时增加幅度明显较小。PD 患者在条件脉冲时也表现出明显且一致的 ICI 和 ICF 减少。在健康受试者中，ICI 和 ICF 与 MEP 阈值相关，但在 PD 患者中不相关。TMS 测量值均与 UPDRS 不相关。
本研究强烈支持 PD 相关 MEP 反映了锥体神经元反应的信号噪声比受到干扰的观点。这种干扰可能是由于传入抑制失衡，导致大脑运动皮层水平的兴奋性/抑制性输入不平衡。
