CONTINUOUS ELECTROENCEPHALOGRAPHIC MONITORING AND SELECTIVE SHUNTING REDUCES NEUROLOGIC MORBIDITY RATES IN CAROTID ENDARTERECTOMY

Purpose: The role of continuous electroencephalography (EEG) monitorin g during carotid endarterectomy was evaluated in this retrospective re view. Methods: We analyzed data from 902 consecutive carotid endartere ctomy procedures performed with vein patch, angioplasty. In 591 operat ions from 1980 to 1988 we did not use intraoperative EEG monitoring or shunting (non-EEG group). Continuous intraoperative EEG monitoring an d selective shunting mere used in 311 procedures from 1988 to 1994 (EE G group). The patients' mean age was higher in the EEG group (68.8 yea rs; range, 41 to 87 years) than in the non-EEG group (66.2 years; rang e, 34 to 90 years; p < 0.001). There was also a significantly higher i ncidence of hypertension (56.2% vs 41.9%) and redo operations (5.4% vs 2.54%) in the EEG group than in the non-EEG group (p < 0.05). The ope rative technique was identical in both groups. We defined a significan t EEG change as a greater than 50% redaction of tile amplitude of the faster frequencies, a persistent increase of delta activity, or both. Results: In the EEG group, acute EEG changes occurred in 40 patients ( 12.8%); 31 (77.5%) unilateral and ipsilateral to the operated carotid artery, and nine (22.5%) bilateral. In five patients (12.5%) the chang es correlated with an intraoperative episode of hypotension, and after normal blood pressure was restored the EEG returned to normal. In 35 procedures (87.5%) a carotid shunt was inserted. In 33 of those patien ts the EEG returned to baseline, in one patient there was a significan t improvement, and in one patient the EEG changes persisted, Postopera tive hospital strokes occurred in one patient (0.32%) in the EEG group and in 13 patients (2.19%) in the non-EEG group (p < 0.05). All strok es (n = 14) were ipsilateral to the operated carotid artery. Of the 13 strokes in the non-EEG group nine were major and four were minor. The one stroke in the EEG group was embolic in origin and occurred before carotid cross-clamping; it was associated with profound EEG changes t hat did nor reverse after placement of a shunt. In tile total group (n = 902), intraoperative EEG monitoring was inversely associated with p ostoperative stroke (p < 0.05). Conclusion: The overall neurologic mor bidity rate was significantly lower in the EEG group than in the non-E EG group, thereby demonstrating the value of intraoperative EEG monito ring in carotid endarterectomy.