Sport-related concussion is known to affect a variety of brain functions. However, the impact of this brain injury on cerebral autoregulation (CA) is poorly understood. Thus, the goal of the current study was to determine the acute and cumulative effects of sport-related concussion on indices of dynamic CA. Toward this end, 179 elite, junior-level (age 19.6 ± 1.5 years) contact sport (ice hockey, American football) athletes were recruited for preseason testing, 42 with zero prior concussions and 31 with three or more previous concussions. Eighteen athletes sustained a concussion during that competitive season and completed follow-up testing at 72 h, 2 weeks, and 1 month post injury. Beat-by-beat arterial blood pressure (BP) and middle cerebral artery blood velocity (MCAv) were recorded using finger photoplethysmography and transcranial Doppler ultrasound, respectively. Five minutes of repetitive squat–stand maneuvers induced BP oscillations at 0.05 and 0.10 Hz (20- and 10-s cycles, respectively). The BP–MCAv relationship was quantified using transfer function analysis to estimate Coherence (correlation), Gain (amplitude ratio), and Phase (timing offset). At a group level, repeated-measures ANOVA indicated that 0.10 Hz Phase was significantly reduced following an acute concussion, compared to preseason, by 23% (−0.136 ± 0.033 rads) at 72 h and by 18% (−0.105 ± 0.029 rads) at 2 weeks post injury, indicating impaired autoregulatory functioning; recovery to preseason values occurred by 1 month. Athletes were cleared to return to competition after a median of 14 days (range 7–35), implying that physiologic dysfunction persisted beyond clinical recovery in many cases. When comparing dynamic pressure buffering between athletes with zero prior concussions and those with three or more, no differences were observed. Sustaining an acute sport-related concussion induces transient impairments in the capabilities of the cerebrovascular pressure-buffering system that may persist beyond 2 weeks and may be due to a period of autonomic dysregulation. Athletes with a history of three or more concussions did not exhibit impairments relative to those with zero prior concussions, suggesting recovery of function over time. Findings from this study support the potential need to consider physiological recovery in deciding when patients should return to play following a concussion.

Repetitive subconcussive head impacts across a season of contact sports participation are associated with a number of deficits in brain function. To date, no research has investigated the effect of such head impact exposure on dynamic cerebral autoregulation (dCA). To address this issue, 179 elite, junior-level (age 19.6 ± 1.5 years) contact sport (ice hockey, American football) athletes were recruited for pre-season testing. Fifty-two non-concussed athletes returned for post-season testing. Fifteen non-contact sport athletes (age 20.4 ± 2.2) also completed pre- and postseason testing. dCA was assessed via recordings of beat-by-beat mean arterial pressure (MAP) and middle cerebral artery blood velocity (MCAv) using finger photoplethysmography and transcranial Doppler ultrasound, respectively, during repetitive squat-stand maneuvers at 0.05 and 0.10 Hz. Transfer function analysis was used to determine Coherence (correlation), Gain (response amplitude), and Phase (response latency) of the MAP-MCAv relationship. Results showed that in contact sport athletes, Phase was reduced (p = 0.027) and Gain increased (p < 0.001) at post-season compared to pre-season during the 0.10 Hz squat-stand maneuvers, indicating cerebral autoregulatory impairment in both the latency and magnitude of the response. Changes in Phase were greater in athletes experiencing higher numbers and severity of head impacts. By contrast, no changes in dCA were observed in non-contact sport controls. Taken together, these results demonstrate that repetitive subconcussive head impacts occurring across a season of contact sports participation are associated with exposure-dependent impairments in the cerebrovascular pressure-buffering system capacity. It is unknown how long these deficits persist or if they accumulate year-over-year.

BackgroundAn integrated curriculum is designed to be repetitive yet progressive and the concept has rapidly established itself within medical education. National organizations have recommended a shift to a spiral curriculum design, which uses both vertical and horizontal integration. This study examined differences between the recently implemented integrated spiral (class of 2019) and conventional block (classes of 2016–2018) MD curricula at the University of British Columbia (UBC) with respect to knowledge of concussion.MethodsCross-sectional online survey (FluidSurveys: Fluidware, Ottawa, ON), distributed via email to UBC medical students during the 2015–2016 academic year. Questions focused on demographic data, knowledge of concussion definition, and management considerations. Differences in responses across the two groups were assessed using chi-square tests. Ordinal Likert-scale data were analyzed using Mann-Whitney U-Tests. Statistical significance was determined a priori at p < 0.05.ResultsOne hundred forty eight medical students (57% female) responded with 78 students in the spiral curriculum and 70 students the block curriculum. Important differences between responses from spiral versus block curricula students included: formal exposure to concussion-related educational material (10.8 h spiral vs. 3.95 h block), understanding concussions can occur without direct head impacts (90% spiral vs. 70% block, X21,148 = 9.41, p = 0.002) and identifying long-term consequences (dementia: 90% spiral vs. 66% block, X21,148 = 12.57, p < 0.0001; second impact syndrome: 80% spiral vs. 57% block, X21,148 = 8.60, p = 0.003; Parkinsonism: 47% spiral vs. 17% block, X21,148 = 14.87, p < 0.001). Block students identified the need for a full neurological exam (X21,148 = 17.63, p < 0.001) and had greater clinical exposure to acute concussion (47% block vs. 14% spiral, X21,148 = 19.27, p < 0.001) and post-concussion syndrome (37% block vs. 19% spiral, X21,148 = 5.91, p = 0.015).ConclusionsThe findings from this preliminary study suggest the spiral curriculum design, which emphasizes and revisits clinical competencies, promotes a strong understanding and retention of knowledge in highly prevalent clinical conditions such as concussion.