术中神经电生理监测在儿童癫痫外科中的应用

Application of intraoperative neurophysiological monitoring in children＇s epilepsy surgery

目的探讨应用术中感觉运动皮质的神经电生理监测指导儿童癫痫手术的可行性、有效性以及安全性。方法连续性回顾性纳入2015年8月至2017年4月北京大学第一医院儿童癫痫中心收治的83例局灶性药物难治性癫痫患儿，均行切除性手术治疗，并予术中神经电生理监测（IOM）。采用体感诱发电位确定中央沟，并直接电刺激初级运动皮质记录运动诱发电位（MEP）以定位运动功能区，之后持续行MEP监测，观察相应肌肉的复合肌肉动作电位（CMAP）的波幅变化。术后至少随访6个月。癫痫发作预后应用Engel分级评估。采用神经系统检查、Peabody运动发育量表及录像的方式，判断有无运动功能障碍。结果80例患儿（80／83，96．4％）完成IOM。监测期间无一例出现癫痫发作及其他不良反应。行MEP监测时能引出肌肉CMAP的最小有效刺激强度为2—38mA，中位数为20mA。相关性分析结果显示，能引出肌肉CMAP的最小有效刺激强度与患儿手术年龄之间存在负相关关系（r=-0．302，P=0．001）。80例患儿的术后无发作率为88．8％（71／80），且不同年龄和手术部位的患儿术后无发作率的差异均无统计学意义（P=0．327，P=0．475）。76例CMAP波幅稳定的患儿术后未见新发的永久性运动功能损伤；4例CMAP消失的患儿中，3例出现新发的永久性运动功能损伤。术中CMAP的稳定性与患儿术后功能预后间具有一致性（P〈0．001）。结论对于儿童局灶性药物难治性癫痫患者，手术中应用IOM安全、可行。儿童癫痫患者术中持续MEP监测需采用的刺激强度较高，且与年龄呈负相关。IOM可实时客观地反映癫痫患儿的运动功能状态，有助于在保护其运动功能的前提下充分切除致痫区，获得良好的预后。

Objective To investigate the feasibility, efficacy and safety of intraoperative neurophysiological monitoring （IOM） in epilepsy surgery for children. Methods A retrospective study was conducted on the clinical data of 83 children with drug-resistant epilepsy who underwent resective surgery and IOM at Children Epilepsy Center, Peking University First Hospital from August 2015 to April 2017. We used the phase reversal technique of somatosensory evoked potential to identify the central sulcus and motor evoked potential （MEP） by direct electrical stimulation of primary motor cortex to map the motor function. MEP was continuously monitored to observe the change of amplitude of compound muscle action potential （CMAP） recorded from various muscles. The seizure outcome was evaluated by Engel classification. The motor function was evaluated by the results of nerve system examination, Peabody motor development scale and video of the patients. Results Out of 83 patients, 80 （96.4%） received successful IOM. No seizures or other adverse events were observed during IOM in this series. The range of minilnmn effective electrical stimulation which can evoke CMAP at muscles was 2 -38 mA, with the median of 20 mA. There was a negative correlation between this minimum effective stimulation and age （r = -0. 302, P =0. 001 ）. The rate of seizure free was 88.8% （71/80） in this study and there was no correlation between ages and sites of surgery （ P = 0. 327, P = 0. 475 ）. There was no new permanent motor deficit in 76 patients who demonstrated stable CMAP during IOM. On the other hand, 3 out of 4 patients who had irreversible disappearance of CMAP during IOM developed new permanent motor deficits post surgery. There was significant correlation between stable CMAP and good motor outcome （P 〈 0. 001 ）.Conclusions IOM is safe and can be ued in children＇ s epilepsy surgery. The electrical stimulation intensity during continuous MEP monitoring in children should be relatively elevated, and there is significant negative correlation between electrical stimulation and age. IOM could reflect the motor function in real time during surgery, and epileptogenic zone could be resected as completely as possible with good protection of motor function at the same time. The patients might have a good outcome as seizure free without new motor deficits,