To examine the association between heart rate variability (HRV) and pediatric concussion outcomes. We hypothesized that HRV would be related to both clinical symptoms and cognition and that HRV parameters at 2-weeks post-injury would predict outcomes at 5 weeks.

Despite the growing prevalence of concussion among children, research focusing on an objective measure of recovery is lacking. Evidence suggests that dysregulation of the autonomic nervous system may be present following concussion. HRV, an objective measure of autonomic function, could prognosticate persistent symptoms following pediatric concussion.

Forty-five concussed children were evaluated 2 weeks and 5 weeks post-injury. Clinical symptoms were evaluated using the Rivermead Post-Concussion Symptoms Questionnaire (RPQ). Cognition was assessed using a modified CogState Brain Injury Test Battery. Time-domain (SDNN, RMSSD, NN50) and frequency-domain (log-transformed values of low- and high-frequency power) variables of HRV were measured during a resting 5-minute recording. Key demographic and injury characteristics, as well as mean heart rate were factored as covariates. 

At 2 weeks post-injury, low-frequency measures showed a positive association with overall RPQ symptoms and Groton Maze Learning and Recall errors (p’s < 0.05). At 5 weeks post-injury, NN50 and low-frequency measures showed a positive association with Groton Maze Learning errors (p’s < 0.05).  At both timepoints, time-domain and high-frequency measures showed a negative association with One-Back task accuracy (p’s < 0.05).  Additionally, time-domain and high-frequency measures at 2 weeks post-injury predicted One-Back task accuracy at 5 weeks post-injury (p’s < 0.05).

Our findings support our hypothesis and indicate that HRV is associated with clinical symptoms and cognitive function post-injury. Importantly, our results also suggest that metrics of HRV collected in the acute phase may serve as a prognostic tool. Additional longitudinal research is warranted in order to replicate the current findings.