title: Predictors of shunt during carotid endarterectomy with routine electroencephalography monitoring.
abstract: BACKGROUND
  The routine use of intraoperative electroencephalography (EEG) monitoring with selective shunt placement during carotid endarterectomy (CEA) has been shown to be safe and effective. We attempt to identify the anatomic and clinical factors associated with significant EEG changes requiring shunt placement during CEA.
  
  
  METHODS
  Between January 2005 and June 2007, 242 CEAs were performed with selective shunt placement for significant EEG changes. Risk factors assessed include severity of both ipsilateral and contralateral disease, presence of ipsilateral preoperative symptoms, hypertension, coronary artery disease, diabetes, age, gender, and preemptive intraoperative blood pressure manipulation to >or=20% above baseline before cross-clamping. Data were analyzed with the chi(2) test (P < .05 was significant).
  
  
  RESULTS
  CEA was performed for asymptomatic disease in 177 of 242 patients (73.1%). The perioperative stroke rate was 0.8% (2 of 242), and the overall morbidity rate was 4.5%. No patients died. Significant EEG changes requiring shunt occurred in 35 patients (14.46%). Factors associated with carotid shunt placement were moderate ipsilateral carotid artery stenosis (50% to 79%) compared with severe (>or=80%) disease (30.6% vs 11.7%, P = .003) and degree of contralateral carotid stenosis (0% to 49%, 10.8%; 50% to 79%, 10.9%; 80% to 99%, 23.2%; occlusion, 50%; P = .0003). Presence of symptoms, gender, age, hypertension, diabetes, or coronary artery disease, and preemptive intraoperative manipulation of blood pressure were not significant predictors of shunt placement.
  
  
  CONCLUSIONS
  CEA performed with routine EEG monitoring and selective shunt placement is associated with a low risk of perioperative stroke. Identified predictors of significant EEG changes were anatomic factors including degree of contralateral carotid artery disease and moderate ipsilateral carotid artery stenosis (50% to 79%). Although contralateral carotid occlusion has been accepted as indication for shunt placement in the absence of cerebral monitoring, this study suggests that high-grade contralateral disease and moderate ipsilateral carotid stenosis are associated with cerebral ischemia resulting in EEG changes and should prompt consideration for nonselective shunting.
authors.affiliation: Division of Vascular Surgery, Rhode Island Hospital, Warren Alpert School of Medicine at Brown University, Providence, RI 02903, USA.
authors.forename: Tze-Woei
authors.initials: TW
authors.lastname: Tan
authors.forename: Manuel
authors.initials: M
authors.lastname: Garcia-Toca
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Marcaccio
authors.forename: Wilfred I
authors.initials: WI
authors.lastname: Carney
authors.forename: Jason T
authors.initials: JT
authors.lastname: Machan
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Slaiby
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D016893:Carotid Stenosis / Q000503:physiopathology / Q000601:surgery*; D002560:Cerebrovascular Circulation; D004569:Electroencephalography; D016894:Endarterectomy, Carotid / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D020521:Stroke / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D016896:Treatment Outcome