[Experiences with a new EEG spectral analyzer in carotid surgery]

Spectral analysis with the compressed spectral array display (CSA) and calculation of spectral edge frequency (SEF) was performed in 43 cases undergoing endarterectomy of the carotid bifurcation. New neurologic deficit appeared in 2 patients (= 4.6%). One of them died postoperatively (= 2.3%), the other suffered from permanent paralysis of the hand. Another 9 patients showed loss of high frequency activity (= decrease in SEF) without a new deficit in the postoperative period. A significant EEG event was defined as a decrease in SEF after carotid cross clamping for at least 5 min. Fisher's exact probability test revealed a close correlation between these EEG events and neurologic outcome. The sensitivity of the test, which was calculated on true positive and false negative events, was 100%, the specificity, based on true negative and false positive events, was 76%. The predictability of the test, based on all EEG events, was 18%; respectively 40% when calculated on significant events.