Validity of SEP monitoring in carotid surgery. Review and own results.

The sensitivity of intraoperative monitoring by means of somatosensory evoked potentials (SEP) in carotid surgery is to be examined.Prospective clinical investigation. In addition, the influence of circulatory parameters on SEP curves will also be tested.Department of Surgery of a university clinic.A total of 200 patients underwent intraoperative monitoring by means of somatosensory evoked potentials (SEP) during carotid endarterectomy between March 1, 1991 and August 1, 1994.In order to exclude blood pressure variations as a cause for amplitude changes the blood pressure and pulse were documented during the entire phase of preparation and clamping.A significant correlation could not be established between parameters of circulation and amplitude changes (r = 0.0026; p = 0.62). In seven cases of intraoperative amplitude reduction of more than 50% a stroke has been avoided by inserting a shunt. Despite the lack of an amplitude reduction, a watershed stroke of A.cerebri media and A.cerebri posterior occurred in two instances. Taking this into consideration the sensitivity of monitoring is 99.0% at a specificity of 100%.SEP-monitoring in carotid endarterectomy is simple to execute and is superior in sensitivity to EEG analysis. To avoid artefaction by anesthesia, a standard injection anesthesia is recommended. Farfield potentials should also be derived to avoid watershed infarctions.