Heart Rate Variability (HRV) After Traumatic Brain Injury (TBI): A Scoping Review

Objective(s): To summarize literature on autonomic nervous system (ANS) dysfunction following traumatic brain injury (TBI) and to characterize studies based on population, type of heart rate variability (HRV) measurement, and association between HRV and outcomes following injury.

Data Sources: Articles were selected using PubMed. Search criteria for PubMed were “brain injury” OR “concussion” AND “heart rate variability.” Articles were included through December 4, 2022.

Study Selection: Studies were selected if the search terms were identified in any of the search fields, contained an objective measurement of HRV, and were human studies. Exclusion criteria included studies with populations other than TBI or of mixed populations including non-traumatic brain injury, review articles, protocol papers, or studies not published in English. Studies were categorized based on population, ways of measuring HRV, changes in HRV in different populations (mild, moderate-severe, and unknown/mixed), medical outcomes, and clinical symptoms. Of the 250 potential studies that were identified based on the search criteria, 141 were excluded upon reviewing the title and abstract and 46 additional articles were excluded upon a full text review. 63 articles met inclusion criteria and were used for data extraction.

Data Extraction: Titles and abstracts were reviewed for inclusion in full text review by the first author. All the authors then divided the remaining articles that met inclusion criteria and extracted the author, year, and country in which it was published, the study design, the method of HRV measurement and the outcomes.

Data Synthesis: Sixty-three articles were included in the final review and studies varied on age of participants and TBI severity (40% acutely post-injury, 51% mild TBI, 51% adults, 67% males>females). Studies also varied based on the way HRV is measured including types of equipment, placement of sensors, protocols, etc. ECGs were the primary method of HRV data collection across multiple studies and software for measuring HRV was varied. Findings indicated that HRV was abnormal using low frequency (LF), high frequency (HF), root mean square of successive differences (RMSSD), and standard deviation of all N-N intervals (SDNN) acutely across severity and chronically for those with moderate-severe TBI. While not all studies found effects, some indicated an association between HRV and outcomes (functional, medical, psychological, and cognitive).

Conclusions: Findings suggest HRV is altered following TBI. However, methods for measuring HRV vary across studies and standardization of measurement is needed to properly assess the impacts of TBI on HRV.

Author(s) Disclosures: The authors have no disclosures to report.