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A history of multiple concussions does not confer long-term impairments to dynamic cerebral autoregulation
  1. Alexander D Wright1,2,3,4,
  2. Jonathan D Smirl4,
  3. Sarah K Fraser2,
  4. Kelsey Bryk4,
  5. Paul van Donkelaar4
  1. 1University of British Columbia, Vancouver, Canada
  2. 2Southern Medical Program, University of British Columbia Okanagan, Kelowna, Canada
  3. 3Department of Experimental Medicine, Faculty of Medicine, University of British Columbia, Vancouver, Canada
  4. 4School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, Canada

Abstract

Objective To examine the effects of concussion history on an index of cerebral autoregulation in a healthy athlete population.

Design Retrospective Cohort.

Setting Laboratory.

Participants 136 male contact sport athletes (19.1±1.4 years, 66 football, 70 hockey) were recruited; 39 presented with 0 previous concussions, 16 with 3+ previous concussions; exclusion criteria included history of concussion within 6 months.

Intervention Participants completed baseline testing prior to the athletic season. Squat-stand manoeuvres at 0.05 and 0.10 Hz were used to enhance blood pressure (BP) variation. BP and cerebral blood velocity (CBV) in the middle cerebral artery were indexed non-invasively via finger photoplethysmography and transcranial Doppler ultrasound, respectively. Independent variables included sport (2) and concussion history (2).

Outcomes Transfer function analysis point estimates at 0.05 and 0.10 Hz characterised the coherence (correlation), phase (synchronisation), and gain (amplitude buffer) between BP and CBV waveforms during the squat-stand manoeuvres.

Results These findings suggest that, despite reductions in 0.10 Hz phase lead being reported acutely after concussion, multiple concussions do not appear to induce long-term impairments in dynamic cerebral autoregulation metrics. This is an important revelation as it indicates that the cerebrovasculature is able to adequately recover following the acutely diminished buffering capacity associated with a concussive injury

Conclusions These findings suggest that, despite reductions in 0.10 Hz phase lead being reported acutely after concussion, multiple concussions do not appear to induce long-term impairments in dynamic cerebral autoregulation metrics. This is an important revelation as it indicates that the cerebrovasculature is able to adequately recover following the acutely diminished buffering capacity associated with a concussive injury

Competing interests None.

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