Dizziness reported by patients after concussion may be caused by autonomic nervous system impairment as opposed to vestibular dysfunction, according to recent study results.
In a retrospective review, researchers at Mayo Clinic in Arizona conducted clinical, radiologic and autonomic nervous system (ANS) testing on 21 concussion patients evaluated at the institution’s concussion clinic. All patients displayed significant abnormalities on ANS testing that included excessive tachycardia and unstable blood pressure using tilt-table testing.
Researchers attributed these conditions to adrenergic dysfunction. When calculating for adrenergic baroreflex sensitivity, eight patients demonstrated insufficiency, and five others displayed adrenergic hypersensitivity.
Nearly all patients reported postural lightheadedness — which researchers said more accurately described the dizziness experienced by many concussion patients — and exercise intolerance, while four indicated histories of syncope.
“Autonomic nervous system dysfunction has long been recognized as a possible complication of people with severe traumatic brain injury, but it has rarely been associated with people with concussions or milder forms of brain injury,” researcher Brent Goodman, MD, a Mayo Clinic neurologist, said in a press release.
“This has the potential to change the way we approach concussion patients," added principal investigator David Dodick, MD, a neurologist and director of the Mayo Clinic Concussion Program. "One of the challenges of treating someone with a concussion is to reliably make a diagnosis: to know when the brain is injured and to know when the brain is actually recovered."
"These findings suggest that ANS impairment is a potential [electrophysiological] biomarker for concussion," the researchers concluded. "This novel finding has therapeutic implications for patients reporting dizziness following concussion."
Disclosure: See the study for a full list of relevant disclosures.