title: Predictors of clamp-induced electroencephalographic changes during carotid endarterectomies.
abstract: OBJECTIVE
  Electroencephalograms (EEGs) detect clamp-induced cerebral ischemia during carotid endarterectomy (CEA) and thus impact management and minimize the risk of perioperative stroke. We hypothesized that age, preoperative neurologic symptoms, ≥70% contralateral carotid and bilateral vertebral stenosis increase the probability of clamp-induced EEG changes, whereas ≥70% unilateral carotid stenosis does not.
  
  
  METHODS
  This is an observational cohort study of 299 patients who underwent CEA with EEG monitoring at a single large urban academic medical center in 2009. Univariate and multivariate logistic regression were used.
  
  
  RESULTS
  Seventy percent or greater ipsilateral carotid stenosis decreases the odds of clamp-induced neurophysiologic dysfunction (odds ratio [OR] = 0.43, 95% confidence interval [CI] [0.18, 0.99], P = 0.04) after adjustment for symptomatic status, degree contralateral carotid or vertebral stenosis, and age. Preoperative neurologic symptoms, ≥70% contralateral carotid stenosis, and bilateral extracranial vertebral stenosis independently increase these odds (OR 2.62, 95% CI [1.32, 5.18], P = 0.005; OR 2.84, 95% CI [1.27, 6.34], P = 0.01; and OR 3.58, 95% CI [1.02, 12.53], P = 0.04, respectively), after adjustment for the other factors. Age ≥70 years has no significant impact.
  
  
  CONCLUSIONS
  Preoperative neurologic symptoms, ≥70% contralateral carotid, and bilateral vertebral stenosis increase the probability of clamp-induced ischemia as detected by intraoperative EEG, while ≥70% ipsilateral carotid stenosis decreases it.
authors.affiliation: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA. mvsimon@partners.org
authors.forename: Mirela V
authors.initials: MV
authors.lastname: Simon
authors.forename: Keith H
authors.initials: KH
authors.lastname: Chiappa
authors.forename: Ronan D
authors.initials: RD
authors.lastname: Kilbride
authors.forename: Guy A
authors.initials: GA
authors.lastname: Rordorf
authors.forename: Richard P
authors.initials: RP
authors.lastname: Cambria
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Ogilvy
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Kwolek
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Lamuraglia
authors.forename: Mark F
authors.initials: MF
authors.lastname: Conrad
authors.forename: Karen L
authors.initials: KL
authors.lastname: Furie
mesh_terms: D000046:Academic Medical Centers; D000368:Aged; D001900:Boston; D002545:Brain Ischemia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D016893:Carotid Stenosis / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D003250:Constriction; D004569:Electroencephalography; D016894:Endarterectomy, Carotid / Q000009:adverse effects*; D006801:Humans; D016015:Logistic Models; D016343:Monitoring, Intraoperative / Q000379:methods*; D015999:Multivariate Analysis; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D018616:Ultrasonography, Doppler, Duplex