Neuropsychologic and functional outcome after complicated mild traumatic brain injury.

OBJECTIVE: To investigate the extent to which neuropsychologic and functional outcome after complicated mild traumatic brain injury (TBI) parallels that of moderate TBI recovery.

DESIGN: A longitudinal study comparing neuropsychologic and functional status of persons with complicated mild TBI and moderate TBI at discharge from inpatient rehabilitation and at 1 year postinjury.

SETTING: Rehabilitation hospital with a Traumatic Brain Injury Model System.

PARTICIPANTS: Persons with complicated mild TBI (n=102), each with an intracranial brain lesion documented through neuroimaging and a highest Glasgow Coma Scale (GCS) score in the emergency department between 13 and 15, and 127 persons with moderate TBI.

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURES: FIM instrument, Disability Rating Scale, Community Integration Questionnaire, Wechsler Memory Scale logical memory I and II, Rey Auditory Verbal Learning Test, Trail-Making Test, Controlled Oral Word Association Test, Symbol Digit Modalities Test, Wisconsin Card Sorting Test, and block design.

RESULTS: Few differences in neuropsychologic performance existed between the TBI groups. Less severely impaired information processing speed and verbal learning were seen in the complicated mild TBI group at rehabilitation discharge and 1 year postinjury. Despite overall improvement across cognitive domains within the complicated mild TBI group, some degree of impairment remained at 1 year postinjury on those measures that had identified participants as impaired soon after injury. No differences on functional ability measures were found between the TBI groups at either time period postinjury, with both groups exhibiting incomplete recovery of functional status at the 1-year follow-up.

CONCLUSIONS: When classifying severity of TBI based on GCS scores, consideration of a moderate injury designation should be given to persons with an intracranial bleed and a GCS score between 13 and 15.