In a recent study of mild TBI patients, distinct differences in heart rate and autonomic regulation were found between people with and without a brain injury. People with a mild TBI are more likely than uninjured people to have higher heart rates when supine. When rising from supine to standing, they were more likely than uninjured people to show lowered heart rate and inadequate cardiovagal activity.
However, in all of the patients who showed abnormal heart rate and cardiovagal activity, no abnormalities were actually found during the standard clinical examination. Although cardiovascular problems after mild TBI can easily be overlooked, the authors of the study suggest that these small changes in the cardiovascular system can be a sub-clinical marker for larger heart problems, and may also contribute to the slight, but perplexing, decrease in long-term survival after a mild TBI.
Hilz MJ, Defina PA, Anders S, et al. Frequency analysis unveils cardiac autonomic dysfunction after mild traumatic brain injury. Journal of Neurotrauma. (June 2011).