Bispectral index-guided anaesthesia for intraoperative electrocorticographic analysis in epilepsy surgery: a prospectiveobservational study

Abstract

Objective To explore a rational BIS range for adapting ECoG monitoring during the epilepsy urgery. Method With a prospective observational study after hospital ethics committee approval, 13 adult patients who underwent elective ECoG-guided anterior temporal corticeetomy consecutively were maintaining the BIS at variable values in the range of BIS > 60.BIS51～60,and BIS40～50 groups in all patients. Interictal epileptiform discharges (IEDs) and burst suppression rates (BSRs) admixed spikes were observed in different BIS groups, and the number of epileptiform spikes were compared by using a one-sided sign test;P values 60 IEDs had significant difference (P=0.03), BIS 40～50 verus BIS > 60 and BIS 51～60 BSRs also had statistically significant (P=0.00 and P=0.03), Conclusions (1) The frequency of single spikes or repetitive spike in the epileptogenic zone had increased tendency in BIS-guided general anaesthesia epilepsy surgery;(2)The BSRs admixed epileptiform activity such as spikes or sharp waves presented obviously when deepened the anaesthesia level, especially during BIS 40～50 condition;(3) If BIS monitoring general anesthesia epilepsy surgery is performing,we suggest to control the BIS in the range of 40～50 will benefit for studying the ECoG characteristics, and further,to facilitate localization of the epileptogenic zone for planning the tailored corticectomy;(4)We speculate that the anesthetic agents, particularly remifentanil could enhance epileptiform activity during intraoperative ECoG,whereas, the dose of propofol has significant correlation with the BIS monitoring. Key words: Epilepsy; Epilepsy surgery; Anaesthesia; Bispectral index; Electrocorticography