Wilkinson Marshall F, Kaufmann Anthony M
Can J Neurol Sci. 2014 Mar;41(2):239-45. doi: 10.1017/s0317167100016644.
Hemifacial spasm (HFS) may be due to peripheral axon ephapsis or central motor neuron hyperexcitability. Low facial motor evoked potential (MEP) thresholds or MEP responses to single pulse stimulation (normally multipulse stimulation is needed) may support the central hypothesis.
We retrospectively compared response thresholds for facial MEPs in 65 patients undergoing surgical microvascular decompression (MVD) for HFS and 29 patients undergoing surgery for skull base tumors.
Single pulse stimulation elicited facial Mep in up to 87% of HFS patients whereas only 10% of tumor patients responded to single pulse stimulation. When comparing facial MEP thresholds using multi-pulse stimulus trains the voltage required in the HFS group were significantly lower then in skull base tumor patients (p < 0.001). the MEP latencies and amplitudes at threshold stimulation were similar between the two groups.
these results suggest the facial corticobulbar pathway demonstrates enhanced excitability in HFS.
半面痉挛（HFS）可能是由于周围轴突的偶然接触或中枢运动神经元的过度兴奋所致。较低的面部运动诱发电位（MEP）阈值或对单脉冲刺激的MEP反应（通常需要多脉冲刺激）可能支持中枢假说。
我们回顾性比较了65例因HFS接受外科微血管减压术（MVD）的患者和29例因颅底肿瘤接受手术的患者的面部MEP反应阈值。
单脉冲刺激在高达87%的HFS患者中诱发了面部MEP，而只有10%的肿瘤患者对单脉冲刺激有反应。当使用多脉冲刺激序列比较面部MEP阈值时，HFS组所需的电压明显低于颅底肿瘤患者（p<0.001）。两组在阈值刺激时的MEP潜伏期和波幅相似。
这些结果表明，在HFS中，面部皮质延髓通路表现出兴奋性增强。
