Evoked potential monitoring in carotid surgery: a review of 994 cases.

Intraoperative monitoring of brain function is desirable in carotid artery surgery to detect possible complications, but the monitoring methods must be simple to perform, sensitive, and reliable. Median nerve somatosensory evoked potential (SEP) monitoring fulfills these criteria. Between 1985 and 1990, we performed 994 operations of the carotid artery with SEP monitoring. In 92% of the cases, we were able to obtain viable SEP tracings. In seven cases, irreversible SEP loss was followed by a new neurologic deficit. In one case only, neurologic complications ensued without SEP loss. Although immediate intraoperative therapeutic options are limited, the monitoring enhances patient security by allowing intraoperative detection and postoperative analysis of complications. SEP monitoring appears to be at least as effective as conventional EEG monitoring. The viability, sensitivity, and reliability of newer methods, such as modified spectral EEG analysis, must be measured by this established procedure.