Comparison of brain temperature to core temperature: a review of the literature.

In both animal models and human studies examining acute neurological injury, elevated core temperatures have been shown to exacerbate the degree of neuronal injury. There is an assumption that core temperature and brain temperature are the same. With the introduction of brain temperature monitoring technology, it has become possible to examine the difference between core and brain temperatures. The purpose of this integrated review was to examine the published literature comparing core temperatures (blood, rectal, bladder, and esophageal) with brain temperatures (measured by direct contact with the brain or measured in any of the spaces surrounding the brain, excluding intraoperative measurements). Fifteen studies from 1990 and 2002 were found. All 15 studies found that brain temperature was higher than all measures of core temperature with mean differences of 0.39 to 2.5 degrees C reported. Only three studies employed a t test to examine the differences; all found statistical significance. Temperatures greater than 38 degrees C were found in 11 studies. This review demonstrates that brain temperatures have been found to be higher than core temperatures; however, existing studies are limited by low sample sizes, limited statistical analysis, and inconsistent measures of brain and core temperatures. Because fever is prevalent in acutely injured neurological patients, its detection and treatment are essential interventions. In the absence of brain temperature monitoring, detection of a 'brain fever' may be limited. Future research is needed to further examine the relationship between brain and core temperatures and their impact on intracranial dynamics.