Computed electroencephalographic topographic brain mapping: A new and accurate monitor of cerebral circulation and function for patients having carotid endarterectomy

To determine the usefulness of computed electroencephalographic (EEG) topographic (CET) brain mapping to monitor neurologic function during carotid endarterectomy (CEA), 46 consecutive patients having CEA were monitored preoperatively, intraoperatively, and immediately postoperatively by CET brain mapping and simultaneous 16-lead EEG. Preoperative studies revealed that 7 of 16 asymptomatic patients, 5 of 11 patients with amaurosis fugax, and 8 of 12 patients with transient ischemic attacks (TIAs) had abnormal CET brain mapping suggestive of previous subclinical stroke. EEG was abnormal in only 8 of the 20 patients with abnormal CET brain mapping. Intraoperatively during carotid cross-clamping, ischemic changes were seen on CET brain mapping in 23 patients whereas EEG detected these changes in only 13 patients. Ischemic changes detected by intraoperative CET brain mapping were more likely to occur in patients with previous stroke (six of seven) than in patients without previous stroke (17 of 39), p < 0.05. Patients with changes detected by intraoperative CET brain mapping had an average carotid back-pressure of 38 mm Hg, in contrast to 57 mm Hg for patients without CET brain mapping changes, p < 0.05. After endarterectomy, CET brain mapping revealed new ischemic changes in one patient who awoke with a mild stroke and in one patient who had TIAs and amaurosis fugax within 6 hours of surgery. We conclude that CET brain mapping is a sensitive, accurate, and useful noninvasive monitor of cerebral circulation and function for patients having CEA. This monitor can detect subclinical stroke in asymptomatic patients or in those with amaurosis fugax or TIA. CET brain mapping can also monitor the adequacy of collateral circulation during carotid cross-clamping. Persistent intraoperative and postoperative CET brain mapping abnormalities accurately predict patients who have postoperative neurologic deficits.