title: Continuous electroencephalographic monitoring and selective shunting reduces neurologic morbidity rates in carotid endarterectomy.
abstract: OBJECTIVE
  The role of continuous electroencephalographic (EEG) monitoring during carotid endarterectomy was evaluated in this retrospective review.
  
  
  METHODS
  We analyzed data from 902 consecutive carotid endarterectomy procedures performed with vein patch angioplasty. In 591 operations from 1980 to 1988 we did not use intraoperative EEG monitoring or shunting (non-EEG group). Continuous intraoperative EEG monitoring and selective shunting were used in 311 procedures from 1988 to 1994 (EEG group). The patients' mean age was higher in the EEG group (68.8 years; range, 41 to 87 years) than in the non-EEG group (66.2 years; range, 34 to 90 years; p < 0.001). There was also a significantly higher incidence 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 operative technique was identical in both groups. We defined a significant EEG change as a greater than 50% reduction of the 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 changes 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 patients the EEG returned to baseline, in one patient there was a significant improvement, and in one patient the EEG changes persisted. Postoperative 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 strokes (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 that did not reverse after placement of a shunt. In the total group (n = 902), intraoperative EEG monitoring was inversely associated with postoperative stroke (p < 0.05).
  
  
  CONCLUSIONS
  The overall neurologic morbidity rate was significantly lower in the EEG group than in the non-EEG group, therapy demonstrating the value of intraoperative EEG monitoring in carotid endarterectomy.
authors.affiliation: Department of Vascular Surgery, Baylor College of Medicine, Houston, TX, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Plestis
authors.forename: P
authors.initials: P
authors.lastname: Loubser
authors.forename: E M
authors.initials: EM
authors.lastname: Mizrahi
authors.forename: G
authors.initials: G
authors.lastname: Kantis
authors.forename: Z D
authors.initials: ZD
authors.lastname: Jiang
authors.forename: J F
authors.initials: JF
authors.lastname: Howell
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001166:Arteriovenous Shunt, Surgical; D001794:Blood Pressure; D002339:Carotid Arteries / Q000601:surgery; D002561:Cerebrovascular Disorders / Q000209:etiology; D003250:Constriction; D003700:Delta Rhythm; D004569:Electroencephalography / Q000145:classification; D016894:Endarterectomy, Carotid / Q000009:adverse effects; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications; D007022:Hypotension / Q000503:physiopathology; D015994:Incidence; D002542:Intracranial Embolism and Thrombosis / Q000209:etiology; D007431:Intraoperative Complications / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009460:Neurologic Examination; D011183:Postoperative Complications; D012086:Reoperation; D012189:Retrospective Studies; D016896:Treatment Outcome