Autonomic-Related Symptoms and Their Link to Autonomic Function and Post-concussion Symptoms in Youth Post-concussion.

BACKGROUND: To preliminarily describe autonomic nervous system (ANS) related symptoms and examine their relationship with ANS function and postconcussion symptoms (PCSs) in youth postconcussion. METHODS: Twenty-five youth following concussion (mean age 13.7 ± 2.3 years; 16 females; median 23 (7-66) days postinjury) were included. ANS-related symptoms were assessed using the Composite Autonomic Symptom Score 31 (COMPASS-31). ANS function was evaluated using heart rate and heart rate variability (HRV) measures recorded with the Polar H10 device, during rest and active standing, handgrip, and paced-breathing tests. PCS were assessed using the Post-Concussion-Symptoms-Inventory for Children (PCSI-C). RESULTS: The mean COMPASS-31 score was 19.6 ± 10.4, with the most common reported subscales being pupillomotor (n = 23), gastrointestinal (n = 20), and orthostatic intolerance (n = 19). Moderate significant positive correlations were found between the delta-PCSI-C (prepost injury) and COMPASS-31 scores (rp = 0.52, P = 0.010). Both COMPASS-31 and delta-PCSI-C scores were moderately associated with HRV values in response to the handgrip test (0.43<r < 0.57; P < 0.050). Delta-PCSI-C was also moderately associated with HRV response to the active standing test (0.49; P = 0.022). No significant correlations were found between symptom burden and HRV values at rest or during the paced-breathing test. CONCLUSIONS: All participants reported ANS-related symptoms in COMPASS-31. ANS-related symptoms and PCS severity were moderately associated, and were related to HRV response during handgrip and active standing tests; the better the response during the test, the lower the symptom burden. These results highlight the importance of using specific tools, such as the COMPASS-31, to assess ANS symptoms and dysfunction postconcussion. Further research with a larger sample size and a follow-up period is required.