ELECTROPHYSIOLOGICAL MONITORING FOR SELECTIVE SHUNTING DURING CAROTIDENDARTERECTOMY

Selective shunt during carotid endarterectomy is more and more widespr ead, but it requires a monitoring system able to identify severe brain ischemia correctly. In 255 endarterectomies for severe carotid stenos is, we evaluated cerebral activity by means of sequential use of compu terized two-channel electroencephalogram (EEG) and somatosensory evoke d potentials (SSEPs). In 1.96% of cases, we observed changes referable to severe cerebral ischemia: in one case, in spite of shunting, EEG a symmetry persisted till the end of the operation, and the patient awok e with irreversible aphasia. In two other cases, a progressive disappe arance of the cortical wave (N20) occurred in spite of a normal EEG pa ttern. None of the unshunted patients had postoperative deficit. Compu terized EEG is an easily interpretable method of monitoring and reveal s rapidly developing cerebral ischemia, but severe SSEP changes can oc cur in spite of a normal EEG pattern when cerebral ischemia has a slow onset. Although SSEP monitoring is a slower method of recording, it c an give a finer distinction of less severe cerebral ischemia.