Autonomic Dysfunction after Mild Traumatic Brain Injury.

A mild traumatic brain injury (mTBI) is a complex pathophysiologic process that has a systemic effect on the body aside from solely an impairment in cognitive function. Dysfunction of the autonomic nervous system (ANS) has been found to induce abnormalities in organ systems throughout the body, and may contribute to cardiovascular dysregulation and increased mortality. Autonomic dysfunction, also known as dysautonomia, has been studied in moderate and severe TBI, and has emerged as a major contributing factor in the symptomatology in mTBI as well. Analysis of the ANS has been studied through changes in heart rate variability (HRV), pupillary dynamics, eye pressure, and arterial pulse wave in those with mild TBI. Graded exercise testing has been studied as both a method of diagnosis and as a means of recovery in those with mild TBI, especially in those with persistent symptoms. Given the studies showing persistence of autonomic dysfunction after symptomatic resolution of concussions, further research is needed to establish return to play protocols.