Concussion and the autonomic nervous system: An introduction to the field and the results of a systematic review.
Jon L Pertab, Tricia L Merkley, Alex J Cramond and 3 others
PMID 29660949WHAT IT FOUND
Concussion likely affects autonomic nervous system function, especially reduced parasympathetic activity and poorer responses to exercise, standing, stress, or light.
No high-quality causal evidence or tested treatment was found.
Key findings
01The review included 36 studies, but no Class I study was found.
02In controlled general population studies, 8 of 13 studies found reduced parasympathetic involvement, and 11 of 14 found less efficient autonomic challenge responses.
03The review concluded it is likely that concussion causes autonomic nervous system anomalies.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
No study met the highest quality standard for causation, and all studies with control groups were retrospective. Case studies and case series were included, but they cannot establish causation. The review did not publish a protocol before searching. Autonomic outcomes were so varied that the studies could not be combined statistically. The authors may not have found every relevant study. The review describes associations and proposed treatments, not tested treatment effects.
Declared interests
All authors declared no conflict of interest. Dr. Merkley was granted research time through the Barrow Neurological Institute. No other funding sources were used.
The easy way to misread this
Do not conclude that autonomic testing or any treatment aimed at the autonomic nervous system has been proven to improve concussion symptoms. The review found likely associations, but no study met the highest quality standard, no treatment trials were reviewed, and the authors state these interventions have not been validated in high-quality randomized controlled trials.