Effect of blood alcohol level on Glasgow Coma Scale scores following traumatic brain injury

It is a common clinical perception that alcohol intoxication systematically lowers Glasgow Coma Scale (GCS) scores when evaluating traumatic brain injury (TBI). However, the research findings in this area do not uniformly support this notion. The purpose of this study is to examine the effects of blood alcohol level (BAL) on GCS scores following TBI.

Participants were 475 patients (64% male) who presented to a Level 1 trauma centre following a TBI. Patients were selected if they were injured in a motor vehicle accident and had an available day-of-injury GCS, BAL and Computed Tomography (CT) brain scan.

Overall, acute alcohol intoxication did not significantly affect GCS scores, even in patients with BALs of 200 mg dl(-1) or higher. When controlling for the effects of injury severity, acute alcohol intoxication affected GCS scores only in those patients with BALs greater than 200 mg dl(-1) who also had intracranial abnormalities detected on CT scan.

These findings suggest that GCS scores can be interpreted at face value in the vast majority of patients who are intoxicated. However, GCS scores will likely over-estimate the severity of brain injury in patients with abnormal head CT scans and BALs greater than 200 mg dl(-1).