Posttraumatic Amnesia as a predictor of outcome after severe closed head injury. Prospective assessment.

OBJECTIVES: To identify the demographic and clinical variables related to the duration of posttraumatic amnesia after severe closed head injury; to evaluate the usefulness of posttraumatic amnesia duration in predicting outcome at the time of hospital discharge and at 6 months after injury.

SETTING: Four clinical centers located in primary care hospitals.

PATIENTS: Three hundred fourteen severely injured subjects aged 16 years or older who did not have trauma as a result of a penetrating injury and came out of coma before hospital discharge.

INTERVENTIONS: Approximately half of the subjects were administered phenytoin sodium for some period after termination of coma; 17% were administered dexamethasone and 41% morphine sulfate.

MAIN OUTCOME MEASURES: Galveston Orientation and Amnesia Test scores defined the duration of posttraumatic amnesia. The Glasgow Outcome Scale was used to grade outcome at the time of hospital discharge and at 6 months.

RESULTS: Older age, low initial Glasgow Coma Scale score, nonreactive pupil(s), coma duration, and use of phenytoin were associated with a longer duration of posttraumatic amnesia. Poor pupillary response, time in coma, and duration of posttraumatic amnesia and use of phenytoin was predictive of the 6-month outcome.

CONCLUSIONS: The results support the prognostic usefulness of prospectively measuring duration of posttraumatic amnesia after termination of coma. Pending replication, our findings suggest that posttraumatic amnesia duration may be a useful surrogate outcome measure for clinical trials involving interventions for acute head injury.