Autonomic Dysfunction in Pediatric Concussion: Differences in HRV and Resting Heart Rate Across Recovery Phases

Background: Autonomic dysfunction is a common sequela in pediatric patients following concussion and may play a role in the persistence of symptoms beyond the acute recovery period. Heart rate variability (HRV) and resting heart rate (HR) are accessible and non-invasive markers of autonomic nervous system function. Variations in these metrics may help distinguish between typical acute recovery and prolonged post-concussive symptoms (PPCS). This study investigates whether HRV and resting HR differ between pediatric concussion patients in the acute versus chronic stages of recovery. Identifying such differences may enhance early recognition of at-risk patients and support development of timely, targeted interventions. Hypothesis: Pediatric patients with chronic PPCS will exhibit greater autonomic dysfunction reflected in altered HRV and resting HR compared to those in the acute phase of concussion recovery. Methods: Data from 408 pediatric concussion patients were retrospectively analyzed and divided into acute (<30 days post-injury; n=195) and chronic (≥30 days post-injury; n=213) groups. HRV and resting HR values were obtained from standardized autonomic testing protocol prior to exertional testing. Group comparisons were performed using the Mann-Whitney U test, and effect sizes were calculated using Cohen’s d. Results: Resting heart rate was significantly higher in the chronic group compared to the acute group (Acute Mean: 70.4 bpm, Chronic Mean: 75.9 bpm; p < 0.00001; Cohen’s d = 0.451, medium-large effect size). HRV Score was significantly lower in the chronic group (Acute Mean: 57.78, Chronic Mean: 55.46; p = 0.003), although the effect size was small (Cohen’s d = -0.218). Conclusion: Pediatric patients with chronic PPCS exhibited significantly elevated resting heart rate and reduced HRV compared to those in the acute phase of recovery, suggesting autonomic dysregulation. Elevated resting HR may reflect increased sympathetic activity or reduced parasympathetic tone, while the lower HRV Score indicates diminished autonomic flexibility. These findings support the potential utility of resting HR and HRV as accessible physiological markers for identifying individuals at risk for prolonged post-concussive symptoms. Further research is needed to validate their predictive value and role in guiding early intervention strategies.