Abstracts

Rationale: Moyamoya disease, a condition predisposing affected individuals to strokes secondary to pathological narrowing of the intracranial internal carotid arteries and their branches, can be successfully treated with surgical revascularization of the brain. One of the major risks of surgical treatment is intraoperative stroke, yet there remains no commonly accepted method to monitor for ischemic changes during the procedure. Interestingly, there is extensive experience with the use of intraoperative electroencephalography (EEG) to monitor for cerebral ischemia during carotid endarterectomy, an operation done for atherosclerotic disease of the carotid artery in the neck. Recognizing the potential utility of this technique in moyamoya surgery, our institution has routinely used intraoperative EEG monitoring during moyamoya operations since 1994, using modified EEG montages to accommodate for the craniotomy incisions. Here we report on our experience with this technique. Methods: The case records and intraoperative EEG recordings of all patients (n=220 patients undergoing 398 craniotomies) treated with surgical revascularization for moyamoya (pial synagiosis) disease performed over a 14 year period (1994-2008) were reviewed. Results: EEG slowing occurred in 100 cases (45.5%) and was persistent in 9 cases (9%). Slowing coincided with specific operative manipulations, most commonly during suturing the donor vessel to the pia, and at the time of closure of the craniotomy. Slowing generally occurred bilaterally and was independent of the side of intervention. The presence, length, and severity of observed EEG slowing was not predictive of perioperative ischemic events Conclusions: This study demonstrates that intraoperative EEG recording using modified EEG montage is technically feasible, even with bilateral craniotomies. While not predictive of perioperative ischemic events in this series, EEG changes could be correlated with specific operative interventions and interestingly revealed global responses to unilateral manipulation. These findings suggest that prospective analysis of this technique may elucidate additional methods of predicting - and possibly preventing - perioperative ischemic events.