Neurobiological Effect of Selective Brain Cooling After Concussive Injury

Open Access
Author:
Walter, Alexa Elizabeth
Graduate Program:
Kinesiology
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 24, 2017
Committee Members:
  • Semyon Slobounov, Thesis Advisor
Keywords:
  • concussion
  • selective brain cooling
  • MRI
  • EEG
  • Virtual Reality
Abstract:
The search for effective treatment facilitating recovery from concussive injury, as well as reducing risk for recurrent concussion, is an ongoing challenge. This study aimed to determine: a) feasibility of selective brain cooling to facilitate clinical symptoms resolution, and b) biological functions of the brain within athletes in acute phase of sports-related concussion. Selective brain cooling for 30 minutes using WElkins sideline cooling system (at 5°C) was administered to student-athletes suffering concussive injury (n=24) and those without history of concussion (n=24). Magnetic resonance imaging (MRI), such as functional magnetic resonance imaging (fMRI) and arterial spin labeling (ASL) sequences, or electroencephalography (EEG) and virtual reality (VR) testing was done before and immediately after cooling to better understand the mechanism by which cooling affects neurovascular coupling. Concussed subjects self-reported temporary release of physical symptoms immediately after the cooling session. EEG results revealed no significant differences pre- to post-cooling for either group; however the was a significant interaction of cooling on ROI and condition, F(1.083, 23.821) = 12.982, p<0.005 in the delta frequency regardless of group. Concussed subjects also showed a differential response to cooling compared to the normal controls. For VR, one-third of concussed subjects could not tolerate testing due to reoccurrence of symptoms, but those who did complete testing had decreased scores post-cooling. There were no differences in the number or strength of functional connections within Default Mode Network (DMN) between groups prior to cooling. However, we observed a reduction in the strength and number of connections of the DMN with other ROIs in both groups after cooling. ASL sequences for the concussed group revealed a significant increase (p<0.05) in relative cerebral blood flow (relCBF) in cortical and subcortical cortex post-cooling while the normal group had significantly decreased (p<0.05) relCBF post-cooling. We suggest that compromised neurovascular coupling in acute phase of injury may be temporary restored by cooling to match CBF with surges in the metabolic demands of the brain. Upon further validation, selective brain cooling could be a potential clinical tool in the identification pathological changes after concussion.