title: The heterogeneity of mild traumatic brain injury: Where do we stand?
abstract: OBJECTIVE
  To explore the heterogeneity of mild traumatic brain injury (mTBI).
  
  
  METHODS
  Hospital-based prospective follow-up study of 125 patients with mTBI sub-divided into 'severity' sub-groups on the basis of GCS scores (GCS of 15 = mild sub-group; GCS of 13-14 = moderate sub-group). Post-traumatic amnesia (PTA) duration (30 minutes used as a cut-off) was also used to define group membership for secondary analyses. The follow-up assessment consisted of a brief neuropsychological battery as well as measures of neurobehavioural functioning, community integration and post-concussive symptomatology. CT scanning was also obtained when clinically relevant.
  
  
  RESULTS
  The two mTBI sub-groups, as defined by GCS scores, did not differ with respect to post-concussive symptomatology, neurobehavioural symptoms, neuropsychological performance or CT scan abnormalities. In contrast, when group membership was redefined on the basis of PTA, the two sub-groups differed significantly with respect to intracranial abnormalities and report of aggressive or disinhibited behaviours at the 6-month mark.
  
  
  CONCLUSIONS
  While the notion of heterogeneity in mTBI was not supported when severity was based on GCS scores, there was partial support when PTA duration was used as a measure of severity.
authors.affiliation: Department of Psychology, The Ottawa Hospital, Ontario, Canada. atellier@ottawahospital.on.ca
authors.forename: Andrée
authors.initials: A
authors.lastname: Tellier
authors.forename: Shawn C
authors.initials: SC
authors.lastname: Marshall
authors.forename: Keith G
authors.initials: KG
authors.lastname: Wilson
authors.forename: Andra
authors.initials: A
authors.lastname: Smith
authors.forename: Mary
authors.initials: M
authors.lastname: Perugini
authors.forename: Ian Gilmour
authors.initials: IG
authors.lastname: Stiell
mesh_terms: D000328:Adult; D000647:Amnesia / Q000175:diagnosis* / Q000209:etiology; D000704:Analysis of Variance; D001930:Brain Injuries / Q000145:classification / Q000150:complications / Q000175:diagnosis*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011446:Prospective Studies; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires