title: Early somatosensory evoked potential grades in comatose traumatic brain injury patients predict cognitive and functional outcome.
abstract: OBJECTIVE
  To relate early somatosensory evoked potential grades from comatose traumatic brain injury patients to neuropsychological and functional outcome 1 yr later; to determine the day (within the first week after traumatic brain injury) that somatosensory evoked potential grade best correlates with outcome; to determine whether somatosensory evoked potential grade improvement in the first week after traumatic brain injury is associated with improved outcome.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Critical care unit at a university hospital.
  
  
  METHODS
  Median nerve somatosensory evoked potentials were obtained from 81 comatose patients with traumatic brain injury. Somatosensory evoked potential grades were calculated from results obtained on days 1, 3, and 7 after traumatic brain injury. Glasgow Outcome Scale, Barthel Index, Rivermead Head Injury Follow-up Questionnaire, General Health Questionnaire, Stroop Color-Word Test, Paced Auditory Serial Addition Task, and Symbol-Digit Modalities Test scores were obtained 1 yr after injury.
  
  
  METHODS
  None.
  
  
  RESULTS
  Somatosensory evoked potential grade on days 1, 3, and 7 related significantly with Glasgow Outcome Scale and Barthel scores (day 3 better than day 1) but did not relate with Rivermead Head Injury Follow-up Questionnaire or General Health Questionnaire scores. Day 3 and day 7 somatosensory evoked potential grades related significantly with Stroop scores. Day 3 somatosensory evoked potential grades related significantly with Symbol-Digit Modalities Test scores. Patients with bilaterally present but abnormal somatosensory evoked potentials, whose somatosensory evoked potential grade improved between days 1 and 3, had marginally better functional outcome than those without somatosensory evoked potential grade improvement.
  
  
  CONCLUSIONS
  Day 3 somatosensory evoked potential grade related to information-processing speed, working memory, and the ability to attend to tasks 1 yr after traumatic brain injury. Day 3 somatosensory evoked potential grade had the strongest relationship with functional outcome. Somatosensory evoked potential grades were not related to emotional well-being.
authors.affiliation: Department of Surgical Neuromonitoring, Sunnybrook Health Sciences Centre, Toronto, ON, Canada. david.houlden@sunnybrook.ca
authors.forename: David A
authors.initials: DA
authors.lastname: Houlden
authors.forename: Amanda B
authors.initials: AB
authors.lastname: Taylor
authors.forename: Anthony
authors.initials: A
authors.lastname: Feinstein
authors.forename: Rajiv
authors.initials: R
authors.lastname: Midha
authors.forename: Allison J
authors.initials: AJ
authors.lastname: Bethune
authors.forename: Craig P
authors.initials: CP
authors.lastname: Stewart
authors.forename: Michael L
authors.initials: ML
authors.lastname: Schwartz
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000150:complications* / Q000175:diagnosis* / Q000628:therapy; D003072:Cognition Disorders / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D015331:Cohort Studies; D003128:Coma / Q000150:complications / Q000175:diagnosis / Q000628:therapy; D003422:Critical Care / Q000379:methods; D042241:Early Diagnosis; D005073:Evoked Potentials, Somatosensory; D005260:Female; D005500:Follow-Up Studies; D015600:Glasgow Coma Scale; D023261:Glasgow Outcome Scale; D006785:Hospitals, University; D006801:Humans; D015601:Injury Severity Score; D007362:Intensive Care Units; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D011336:Probability; D011446:Prospective Studies; D020127:Recovery of Function; D018570:Risk Assessment; D018709:Statistics, Nonparametric; D055815:Young Adult