Neurologists at Mayo Clinic in Arizona have taken a promising step toward identifying a test that helps support the diagnosis of concussion. Their research has shown that autonomic reflex testing, which measures involuntary changes in heart rate and blood pressure, consistently appear to demonstrate significant changes in those with concussion.
I've been reading, thinking, and writing about autonomic nervous system issues in connection with TBI for some time, now. The connection is pretty obvious to me, and I believe it also contributes to the development of PTSD after concussion/TBI. There is an important connection between the two, and I'm convinced that autonomic nervous system issues are significant contributors to both the trauma that comes from TBI (after the injury, not just before/during), and our physiological and psychological responses to it.