title: Detection of electrographic seizures with continuous EEG monitoring in critically ill patients.
abstract: OBJECTIVE
  To identify patients most likely to have seizures documented on continuous EEG (cEEG) monitoring and patients who require more prolonged cEEG to record the first seizure.
  
  
  METHODS
  Five hundred seventy consecutive patients who underwent cEEG monitoring over a 6.5-year period were reviewed for the detection of subclinical seizures or evaluation of unexplained decrease in level of consciousness. Baseline demographic, clinical, and EEG findings were recorded and a multivariate logistic regression analysis performed to identify factors associated with 1) any EEG seizure activity and 2) first seizure detected after >24 hours of monitoring.
  
  
  RESULTS
  Seizures were detected in 19% (n = 110) of patients who underwent cEEG monitoring; the seizures were exclusively nonconvulsive in 92% (n = 101) of these patients. Among patients with seizures, 89% (n = 98) were in intensive care units at the time of monitoring. Electrographic seizures were associated with coma (odds ratio [OR] 7.7, 95% CI 4.2 to 14.2), age <18 years (OR 6.7, 95% CI 2.8 to 16.2), a history of epilepsy (OR 2.7, 95% CI 1.3 to 5.5), and convulsive seizures during the current illness prior to monitoring (OR 2.4, 95% CI 1.4 to 4.3). Seizures were detected within the first 24 hours of cEEG monitoring in 88% of all patients who would eventually have seizures detected by cEEG. In another 5% (n = 6), the first seizure was recorded on monitoring day 2, and in 7% (n = 8), the first seizure was detected after 48 hours of monitoring. Comatose patients were more likely to have their first seizure recorded after >24 hours of monitoring (20% vs 5% of noncomatose patients; OR 4.5, p = 0.018).
  
  
  CONCLUSIONS
  CEEG monitoring detected seizure activity in 19% of patients, and the seizures were almost always nonconvulsive. Coma, age <18 years, a history of epilepsy, and convulsive seizures prior to monitoring were risk factors for electrographic seizures. Comatose patients frequently required >24 hours of monitoring to detect the first electrographic seizure.
authors.affiliation: Division of Critical Care Neurology, Department of Neurology, College of Physicians and Surgeons, Columbia University, New York 10032, USA. jc1439@columbia.edu
authors.forename: J
authors.initials: J
authors.lastname: Claassen
authors.forename: S A
authors.initials: SA
authors.lastname: Mayer
authors.forename: R G
authors.initials: RG
authors.lastname: Kowalski
authors.forename: R G
authors.initials: RG
authors.lastname: Emerson
authors.forename: L J
authors.initials: LJ
authors.lastname: Hirsch
mesh_terms: D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000008:administration & dosage / Q000627:therapeutic use; D001927:Brain Diseases / Q000150:complications; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003128:Coma / Q000209:etiology / Q000503:physiopathology; D003244:Consciousness Disorders / Q000209:etiology / Q000503:physiopathology; D003422:Critical Care / Q000379:methods* / Q000706:statistics & numerical data; D016903:Drug Monitoring; D004569:Electroencephalography; D004827:Epilepsy / Q000150:complications / Q000188:drug therapy; D005260:Female; D006801:Humans; D007223:Infant; D007297:Inpatients; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010424:Pentobarbital / Q000008:administration & dosage / Q000627:therapeutic use; D012189:Retrospective Studies; D012640:Seizures / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D013345:Subarachnoid Hemorrhage / Q000150:complications; D016896:Treatment Outcome
chemical_list: D000927:Anticonvulsants; D010424:Pentobarbital