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Further Experience with Computerized Topographic Brain Mapping and Selective Shunting During Carotid Endarterectomy

Computerized topographic brain mapping (CTBM) is a method of identifying cerebral ischemia and can be used to select patients for temporary shunt placement during carotid endarterectomy (CEA). The purpose of this article is to review our experience with CEA and CTBM. From 1990 to 1993, 279 elective CEAs were performed using intraoperative CTBM. The indications for surgery were TIA, amaurosis fugax, and/or previous stroke in 84% of patients. Overall, the permanent deficit rate (including one death) was 1.1%. The temporary deficit rate was 1.8%. Postoperative transient ischemic attacks were seen in 1.1%. No ischemic changes were seen with carotid clamping during 237 CEAs (85%). The rate of postoperative neurologic deficits in this group was 1.7%, compared to 9.5% of the 42 CEAs (15%) with ischemic changes, p<0.00). Of the 86 patients with contralateral high-grade stenosis (>80%) or occlusion, the deficit rate was 7.0%, versus 1.0% in the remaining 193 patients who had mild to moderate contralateral stenosis, p<0.001. The frequency of CTBM changes leading to shunt placement, as well as the frequency of shunt placement by surgeon's preference, decreased throughout the study period (23% to 11% and 10% to 1.4%, respectively). In conclusion, CTBM is a safe, sensitive and reliable method of identifying cerebral ischemia during CEA that may be used to minimize shunt placement. Patients with significant contralateral carotid artery disease are at increased risk for intraoperative cerebral ischemia and postoperative neurologic events.