Acute sport-related concussion induces transient impairment in dynamic cerebral auto regulation that is related to scat3 performance. Issue 11 (25th May 2017)

• Record Type: Journal Article
• Authors: Wright, Alexander D; Smirl, Jonathan D; Bryk, Kelsey; Fraser, Sarah K; Grewal, Harjas S; Jakovac, Michael; Dierijck, Jill; Donkelaar, Paul van
• Is Part Of: British journal of sports medicine. Volume 51:Issue 11(2017)
• Page Start: A38
• Page End: A38
• Publication Date: 2017-05-25
• Subjects: Sports medicine -- Periodicals; 617.1027
• DOI: 10.1136/bjsports-2016-097270.96
• Languages: English
• ISSNs: 0306-3674

Abstract

Abstract : Objective: Examine how the frequency-dependent relationship between blood pressure (BP) and cerebral blood velocity (CBV) is affected by acute sport-related concussion. Design: Prospective Cohort. Setting: Laboratory. Participants: 136 male contact-sport athletes (19.1±1.4 years) recruited, subset of 14 sustained concussions (19±1.4 years). Intervention: Participants completed baseline (T0) and post-injury testing at 72-hours (T1), 2-weeks (T2), and 1-month (T3). BP was monitored via finger photoplethysmography, and transcranial Doppler ultrasound indexed CBV in the middle cerebral artery. Squat-stand manoeuvers were performed at 0.05 and 0.10Hz to enhance BP variation. RM-ANOVA independent variables included time (4) and frequency (2). Outcome measures: Transfer function analysis point estimates quantified coherence (correlation), phase (synchronisation) and gain (amplitude buffer) metrics between BP and CBV waveforms. Results: Significant frequency-time interactions for phase (p=0.007) and gain (p=0.049). Simple effects analysis revealed time effects for phase at 0.10 Hz, indicating reductions at T1 (95% CI: 0.033 – 0.24 rads, p=0.008) and T2 (95% CI: 0.014–0.196 rads, p=0.02) compared to T0. On average, return-to-play occurred at T2 (median 14 days). Phase reductions at T1 were correlated with Standardised Assessment of Concussion performance (r=0.659, p=0.02). Conclusions: These results reveal transient post-concussion impairments in the capacity of the cerebrovasculature to buffer BP oscillations, which exceeded clinical recovery duration. Phase reductions at 0.10Hz suggest the presence of a cerebrovascular autonomic dysregulation, which could leave the brain less protected to BP surges. This key finding may help explain why the brain is more vulnerable to additional trauma during the post-injury recovery period. Competing interests: None.