低剂量肌松剂麻醉下听神经瘤手术面神经监测

Facial nerve monitoring under low dosage of muscle relaxant assisted anesthesia during resections of acoustic neurinomas

目的探讨肌松剂辅助麻醉对听神经瘤手术面神经电生理监测的影响及其可行性。方法对2002年以来我科在低剂量非去极化肌松剂辅助全麻下所行的120例听神经瘤术中面神经监测的资料进行归纳、分析和整理。面神经监测主要采用两种方式：自发连续肌电图（online EMG）和间断面神经疑似组织电刺激诱发肌电图（triggered EMG）监测。结果多数患者online EMG监测未出现有指导意义的肌电信号。triggered EMG监测可示踪面神经的解剖行程，且不同刺激电流所诱发的肌电变化与术后面神经功能相关。肿瘤全切后，直接刺激面神经脑干端可诱发面肌动作电位的最小电流为0．4mA，最大为13．8mA。若面神经结构功能基本完整，刺激电流主要在0．4～4mA之间，相应术后近期面神经功能优良（H—BⅠ～Ⅱ级）率为63．3％（76／120），而刺激电流2mA以下诱发面肌电位波幅和／或波形下面积达0．1mV以上者，术后面神经功能优良率达100％。结论低剂量非去极化肌松剂辅助麻醉下面神经triggered EMG监测对术中面神经解剖定位、功能判定和术后功能预测具有指导价值。

Objective To explore the feasibility and effect of muscle relaxant assisted anesthesia on the facial nerve monitoring during the resections of acoustic neurinomas. Methods The data of facial nerve monitoring in 120 patients with acoustic neurinomas, which had been resected under the general anesthesia assisted by low dosage of non-depolarized muscle relaxant since 2002, were retrospectively analyzed and summarized. There were two monitoring methods： spontaneously continuous electromyogram （online EMG） and discontinuously triggered facial nerve electromyogram （triggered EMG）. Results There were not any valuable electromyographic signals in online EMG for most of the patients, however, triggered EMG monitoring could trace the anatomical route of facial nerve. The electromyographic responses triggered by different scales of stimulating current were related with different grades of facial nerve function after operation. The threshold of stimulating current in the exit-zone of facial nerve was 0.4 -13.8 mA in this group. The threshold between 0.4 mA and 4 mA corresponded to 63.3% of （76/120） good facial nerve function （H-B grade Ⅰ-Ⅱ） at the first day after operation, while stimulating current ≤ 2 mA with more than 0. 1 mV in amplitude and/or covering area of waves corresponded to 100% of good function. Conclusion It is valuable for triggered EMG to detect the anatomic course of facial nerve and estimate its functional state during operation under the general anesthesia assisted by low dosage of non-depolarized muscle relaxant. It can also be used to predict facial nerve function after operation.