Early detection of cerebral ischemia during carotid endarterectomy using transcranial Doppler sonography and somatosensory evoked potentials

Cerebral function during carotid endarterectomy can reliably be monitored using somatosensory evoked potentials (SEP). Transcranial Doppler sonography (TCD) is a noninvasive method providing on-line data about cerebral hemodynamics. The combination of both techniques during carotid surgery is helpful in evaluating the hemodynamic ("input") and the functional ("output") consequences of carotid clamping within a short time. In the present report, combined TCD and SEP monitoring early detected left hemispheric ischemia in a 68-year-old woman subjected to left carotid endarterectomy. The impairment of cerebral perfusion occurred before carotid clamping due to an intraoperative thrombosis of the left internal carotid artery as could be revealed after declamping. A temporary shunt was not inserted. Postoperatively, the patient had a new transient neurological deficit. In this case, TCD correctly indicated cerebral ischemia as confirmed by SEP recording. For carotid artery surgery, combined TCD and SEP may be helpful in detecting those patients who will profit from temporary shunting if this is not done routinely.