Dynamic Cerebral Blood Flow Velocity Assessment during Head Down Tilt in Sports-Related Concussions
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AbstractIntroduction: Sport-related concussions affect between 1.6 and 3.8 million people in the United States per year (Langlois et al., 2006). Approximately 5% to 10% of children and adolescents will experience a sport-related concussion in their lives (Conder & Conder, 2015). Concussions can lead to alterations in cerebral blood flow in the brain; it has been noted that CBF decreases immediately after a concussion (Maugans, Farley, Altaye, Leach, & Cecil, 2011). A decrease in CBF has been linked to cognitive dysfunction and a longer recovery time (Churchill, Hutchison, Graham, & Schweizer, 2017). Cerebral autoregulation is the ability to maintain a stable cerebral blood flow in the face of fluctuating cerebral perfusion pressure, which has been shown to be impaired in concussed individuals. This study hypothesizes that there will be an increase in cerebral blood flow velocity immediately after a head down tilt test. This increase will be brought back down to baseline in healthy controls due to an intact cerebral autoregulation. However, in concussed individuals there is a predicted delay in the return to baseline due to impaired cerebral autoregulation.Methods: 5 healthy controls and 5 concussed adolescents were recruited for this study. The concussed group all suffered a sport-related concussion within ten days of testing. The healthy controls did not have a concussion within the year before testing. Each participant had a Transcranial Doppler, Nexfin, and Nonin placed on them before the start of the test. The participant then laid flat for 10 minutes on the tilt table. After the 10 minutes of supine, the head down tilt test began by having the end of the table at the participant’s feet lifted, so that the head was tilted downward at a 6-degree angle. Approximately 4 to 6 weeks later the participants return for their recovery visit where the same procedures are performed. Results: No significant differences were found in cerebral blood flow velocity at Visit 1 between concussed and healthy controls; resting MCA (p = .403), immediately on tilt (p = .345), and five minutes into tilt (p = .693). At visit 2, it is shown that concussed individuals displayed much higher velocities. Discussion: General trends were observed from the data. Cerebral blood flow velocity in a cutely concussed participants at visit 1 showed a decrease in their velocity when compared to healthy controls during supine. Additionally, healthy controls during the tilt test behaved as suspected. During the first 30 seconds of the tilt test healthy controls have an increase in their velocity, that immediately drops back down to the baseline response by the end of the first minute of tilt. However, the acutely concussed at visit 1 shows a blunted response during the tilt test. An increase is shown during the first 30 seconds of tilt, but the velocity does not drop back down to baseline.