The association of a positive blood alcohol level (BAL) and the outcome of traumatic brain injury has recently become a controversial one. Different clinical studies have shown both positive and negative outcomes of brain injury when a positive BAL is present. Although alcohol intoxication increases the risk of brain injury, disability, and mortality, there is some evidence that, in some cases, a positive BAL may contribute to positive outcomes after the injury. Some studies have reported neuroprotective effects of low or moderate levels of alcohol.
Researchers from the University of Southern California recently looked specifically at the effect of a positive BAL in cases of isolated severe traumatic brain injury. Cases of severe brain injury in which there was a positive BAL at intake were compared to those in which there was no or low BAL. They found that the relative risk of mortality was lower in those cases that had high levels of alcohol in their blood than those who had no or low levels.
This difference was only found when the most critically injured patients with major complications were excluded. When the critically injured patients were included in the analysis, there was no difference in mortality between patients with high, no, or low BAL. Therefore, while this study supports the idea that alcohol may contribute to a positive outcome after injury, the risk of death from critical injuries when alcohol is present is still significant.
Talving P, Plurad D, Barmparas G, et al. Isolated severe traumatic brain injuries: Association of blood alcohol levels with the severity of injuries and outcome. The Journal of Trauma Injury, Infection, and Critical Care. (February 2010).