Journal Article

Individuals with persisting post‐concussion symptoms with physiological subtype demonstrate altered cardiovascular and autonomic responses to face cooling

Lidstone, Steve, Wallace, Phillip J., McKinlay, Brandon J., Klassen, Stephen A., Ljubanovich, Johnathan, Cheung, Stephen S., Nowlan, Josh G.

2025

Overview

Individuals with persisting post‐concussion symptoms with physiological subtype (PPCS‐P) demonstrate exercise intolerance due to exacerbation of concussion‐like symptoms during incremental exercise. We tested the hypothesis that individuals with PPCS‐P ( n  = 12) would have a blunted cardiac autonomic response to face cooling compared to healthy controls (CTRL, n  = 12). Participants were supine and performed a 5 min baseline, then experienced a 3 min face cold pressor test followed by 5 min of recovery. A three‐lead electrocardiogram was used to measure heart rate and root mean square of successive differences in R‐R intervals (RMSSD), finger photoplethysmography was used to measure mean arterial pressure (MAP), and laser‐Doppler flowmetry was used to measure finger skin blood flux. The PPCS‐P group had a lower exercise tolerance (9.9 ± 3.2 min, P  < 0.001) and lower peak heart rate (170.0 ± 14.0 beats·min −1 , P  < 0.001) compared to CTRL (19.6 ± 2.5 min; 193.0 ± 5.0 beats·min −1 ). PPCS‐P demonstrated a blunted mean heart rate (CTRL: ∆−4.0 ± 5.0 beats·min −1 , PPCS‐P: ∆2.0 ± 4.0 beats·min −1 ; group effect: P  < 0.001) and mean RMSSD (CTRL: ∆26.6 ± 34.7 ms, PPCS‐P: ∆−1.8 ± 33.9 ms; group effect: P  = 0.026) responses at 2 min of face cooling compared to CTRL. Both groups had a significant increase in MAP during face cooling, where at 2 min, MAP was higher in PPCS‐P (∆+13.2 ± 5.5 mmHg) compared to CTRL (∆+8.7 ± 6.9 mmHg, group effect: P  < 0.001). Furthermore, PPCS‐P had a sustained lower finger skin blood flux (group effect: P  < 0.001) during face cooling (PPCS‐P: ∆−48.2 ± 27.1%, CTRL: ∆−12.8 ± 24.7% at 2 min). These data suggest that individuals with PPCS‐P demonstrate altered cardiac and peripheral autonomic function during face cooling compared to healthy controls. What is the central question of this study? Are there physiological differences in responses to face cooling between individuals who are apparently healthy versus those with persisting post‐concussion symptoms with physiological subtype? What is the main finding and its importance? Compared to controls, individuals with persisting post‐concussion symptoms with physiological subtype exhibited altered autonomic and cardiovascular responses to a face cold pressor test including blunted heart rate variability responses, greater blood pressure responses, and greater finger skin blood flux reductions to face cooling. Persisting post‐concussion symptoms with physiological subtype do not appear to affect cerebral autoregulation. These data suggest that impaired autonomic regulation of the heart and vasculature may mechanistically contribute to persisting post‐concussion symptoms in humans.