脑血流临时阻断中脑电图连续监测的临床意义及局限性

目的 探讨在脑前交通动脉瘤患者手术中，临时阻断脑血流，脑电图监测结果的临床意义及局限性。方法 直接夹闭动脉瘤16例，血管搭桥术后孤立动脉瘤30例。脑电图监测采用皮肤针状电极国际标准10～20系统；手术后12h内行CT扫描检查。结果 6例术前血管造影显示侧支循环不良的患者中，2例在试验性颈内动脉阻断时，出现脑电图的异常改变；其他4例大脑中动脉临时阻断时，无脑电图改变；1例术前造影显示侧支循环良好的患者，颈内动脉试验性阻断时出现脑电图异常改变，改行大脑中动脉阻断，未出现脑电图异常。不论术前血管造影如何，大脑中动脉阻断过程中均未出现脑电图异常改变。手术后CT检查发现基底核区梗死3例，手术造成的皮质损伤3例，基底核区出血1例。在这7例患者中，术中均无脑电图的异常改变。颈内动脉临时阻断时间为5～25min，大脑中动脉为25～50min。结论 在脑血流临时阻断过程中，进行脑电图监测，可以指导脑保护性药物(如巴比妥等)的用量；可提示可能出现的重度缺血性脑损害；但受开颅范围影响，脑电图对手术暴露区域的脑组织，尤其皮质下及脑深部组织不敏感。

Clinical significance and limitations of intraoperative continuous EEG monitoring during temporary occlusion of the cerebral blood flow

Objective To report the results of intraoperative EEG monitoring during temporary occlusion of the cerebral blood flow in 46 operations on anterior circulation aneurysms in the period from Nov. 1997 to Nov. 2002, the clinical significance and limitations of intraoperative EEG monitoring were discussed. Methods The aneurysms were directly clipped in 16 cases, trapped after vascular bypass in 30 cases; EEG was monitored according to the international standard 10-20 system using scalp recording electrodes; CT scan was performed within 12 hours postoperatively. Results Among 6 cases in which the collateral circulation was insufficient as demonstrated in preoperative angiography, abnormal EEG occurred during tentative ICA occlusion in 2 cases; EEG change was not observed in the other 4 cases during MCA occlusion; in one case with sufficient collateral circulation demonstrated in the preoperative angiography, intraoperative tentative ICA occlusion caused abnormal EEG change, but there was no EEG change in the alterative MCA occlusion. There was no intraoperative change EEG during MCA temporary occlusion, irrespective of the findings of the preoperative angiography. Postoperative CT scan demonstrated basal ganglion infarction in 3 cases, cortical injury caused by surgical manipulation in 3 cases and postoperative intra-parenchymal hematoma in the basal ganglion in one case; but there was no intraoperative EEG changes in these 7 cases. The temporary occlusion time was 5-25 minutes in ICA, 25-50 minutes in MCA. Conclusion Intraoperative EEG monitoring could monitor the dosage of barbiturates using for cerebral protection during temporary occlusion of the blood flow; EEG could also suggest potential ischemic damage of the brain; but it may be limited by the extent of the craniotomy. EEG was not sensitive over the exposed brain within the craniotomy, nor the subcortical and deep brain tissue.