A Comparative Study of Cerebrovascular Reactivi ty Using Transcranial Doppler Ultrasonography in Sports-Related Concussion Patients

AbstractObjective: This study aimed to investigate the relationship between changes in cerebrovascular resistance under hyperventilation stress and symptom induction in patients with sports-related concussions (SRCs). Subjects and Methods: Thise study included 51 patients who visited our hospital between January 2020 and December 2023 (19 with a previous history of SRC, 20 without a previous history of SRC,) and 12 control subjects). Using transcranial Doppler (TCD), the resistance index (RI) was calculated from the blood flow in the right middle cerebral artery before and after 1min of hyperventilation stress, and the percentage change in RI (ΔRI rate) was determined. The presence or absence of symptoms before and after hyperventilation were assessed. Results: The ΔRI rate before and after hyperventilation stress was 0.19 in the "Previous History group," 0.25 in the "No-Pprevious Hhistory group," and 0.29 in the "Ccontrol group." Symptom induction rates following hyperventilation stress were 52.6% (10/19) in the "Previous History group," 25% (5/20) in the No Previous History group," and 0% (0/12) in the Ccontrol group. Significant differences were observed in both RI and symptom induction rates between the Previous History and Control groups. Conclusion: In patients with SRC, particularly those with a history of SRC, reduced cerebrovascular reactivity to hyperventilation stress and pronounced symptom induction were observed. These findings suggest that interventions that consider respiratory changes may be beneficial during stepwise return-to-play protocols following the SRC.