经颅磁刺激运动诱发电位在脊柱脊髓术中监测的应用研究

目的 探索应用经颅磁刺激运动诱发电位(TMS-MEP)在脊柱脊髓手术中进行神经监测的可行性和有效性.方法 2001年2月至2004年6月间在我科接受脊柱脊髓手术共37例患者,术中分别使用常规方法和依托咪酯+芬太尼技术进行麻醉,应用双频指数(BIS)和四个成串刺激(TOF)监测麻醉深度与肌松状态,使用TMS-MEP进行术中监测.比较不同麻醉方法和麻醉深度对TMS-MEP的影响,并分析TMS-MEP监测操作的可行性及其对手术操作的影响.结果 以安氟醚或异氟醚维持麻醉的11例患者无法记录到TMS-MEP;使用依托咪酯+芬太尼技术麻醉的26例患者,MEP均记录良好.与麻醉前相比,术中的MEP波形一般都能够保持,但其波幅显著下降、潜伏期亦明显延长(P<0.05).随着麻醉和肌松的加深,MEP的波幅会进一步降低,而潜伏期的变化相对较小.在麻醉相对平稳的情况下,MEP波幅能保持相当的平稳.MEP操作对手术没有明显的不良影响.成功记录MEP的患者中有6例(23%)因为术中MEP波幅下降超过50%而向术者发出报警,其中仅1例患者术后肌力较术前下降.结论 应用TMS-MEP进行脊柱脊髓手术的术中监测是一项有效而切实可行的技术,依托咪酯+芬太尼麻醉技术适用于使用TMS-MEP进行术中监测的手术,BIS、TOF等麻醉、肌松监测指标的应用有助于维持术中麻醉的平稳和对TMS-MEP监测结果的判断.

The utility of transcranial magnetic motor evoked potential monitoring during spinal surgery

Objective To evaluate the practicability and validity of transcranial magnetic motor evoked potential monitoring (TMS-MEP) during spinal surgery. Methods From February 2001 to June 2004, 37 patients undergoing spinal surgery were involved, anaesthesia was maintained with volatile anesthetics in 11 operations and etomidate in 26. Analgesia was provided with fentanyl, and non-depolarizing muscle relaxant was given intermittently. MEPs elicited with transcranial magnetic stimulations were recorded from tibialis anterior muscles, simultaneously bispectral index (BIS) and train-of-four stimulation (TOF) were used to monitor the anesthesia depth and neuromuscular blockade respectively. The variety of MEP and its effect on surgical operation at different anesthesia depth and muscular relaxation were observed, and the muscle strength of the patients before and after operation were compared. Results The 11 cases anesthetized with isoflurane or enflurane gave no response to TMS, the other 26 cases in which anaesthesia was maintained with etomidate and fentanyl gave satisfactory TMS-MEPs, but with significantly attenuated amplitudes and prolonged latencies (P<0.05). Intraoperative MEP showed a grossly unchanged waveform, and its amplitude and latency had little fluctuation when anaesthesia and neuromuscular blockade maintained stable. When T1 value of TOF at 40%-60% , a steady MEP could be acquired and the muscular contraction after TMS should not interfere the operatioa Seven of 26 cases had a MEP amplitude drop up to 50% or more during the operation, the surgical team was notified to avoid further spinal injury, at last only 1 case had a worsen muscle power after operation. Conclusions Myogenic TMS-MEP is a valid and practicable technique for intraoperative monitoring, and the etomidate + fentanyl technique is adequate for its anesthesia. BIS and TOF monitoring are helpful to maintain the steadiness of the anesthesia and MEPs, which is veryimportant for monitoring the changes of the MEPs.