Department of Applied Physiology and Wellness, Simmons School of Education and Human Development, Southern Methodist University, 3101 University Blvd, Dallas, TX 75205, USA; Department of Physical Medicine and Rehabilitation, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390, USA.
Department of Statistical Science, Southern Methodist University, 3225 Daniel Ave, Dallas, TX 75205, USA.
Auton Neurosci. 2019 Sep;220:102548. doi: 10.1016/j.autneu.2019.04.004. Epub 2019 Apr 29.
Although physiological deficits such as altered cerebral blood flow (CBF), and autonomic nervous system (ANS) dysregulation have been reported following a concussion, the relationship between CBF and ANS with functional outcome post-injury remains unclear. Our present study was designed to examine heart-rate variability (HRV) using percentage of successive NN intervals (pNN50) and CBF on day-3 (T1), day-21 (T2), and day-90 (T3) following a concussion in collegiate athletes (N = 31) in comparison to non-injured controls (N = 31). Continuous RR-interval (3-lead electrocardiogram), middle cerebral artery blood velocity (MCAV; transcranial Doppler ultrasonography), mean arterial pressure (MAP; finger photoplethysmography) were obtained at rest. Cerebrovascular conductance index (CVCi) was estimated as a ratio of MCAV to MAP. Cognition was evaluated with standard assessment of concussion (SAC), and Trails A & B. Compared to the controls, lower HRV (43 ± 15 vs. 27 ± 20%; p < 0.0001) was observed at T1 with normalization at T2 and T3. No difference in MCAV between the control and the concussed groups across the three time points were observed. However, post-hoc analyses indicated a positive relationship between MCAV at T1 phase with HRV and CVCi during T2, and T3 phases. Higher MCAV at T1 was also associated with better cognition scores during the asymptomatic T2 phase in the concussed athletes. Therefore, our results indicate ANS dysregulation during the acute recovery phase after a concussion. Differences in CBF may be one of the underlying causes behind heterogeneity in clinical symptoms and functional outcomes after a concussion and future studies are warranted to validate this finding.
尽管据报道，脑血流 (CBF) 改变和自主神经系统 (ANS) 失调等生理缺陷会在脑震荡后发生，但 CBF 与 ANS 与损伤后功能结果之间的关系仍不清楚。我们的研究旨在检查脑震荡后第 3 天 (T1)、第 21 天 (T2) 和第 90 天 (T3) 的大学生运动员 (n = 31) 与未受伤对照组 (n = 31) 的心率变异性 (HRV)，使用连续 NN 间期的百分比 (pNN50) 和 CBF。在休息时获得连续 RR 间隔 (3 导联心电图)、大脑中动脉血流速度 (MCAV；经颅多普勒超声)、平均动脉压 (MAP；手指光容积脉搏波)。脑血管传导指数 (CVCi) 估计为 MCAV 与 MAP 的比值。使用标准脑震荡评估 (SAC) 和 A 和 B 轨迹测试评估认知功能。与对照组相比，T1 时 HRV 较低 (43 ± 15 对 27 ± 20%；p < 0.0001)，T2 和 T3 时恢复正常。在三个时间点，对照组和脑震荡组之间的 MCAV 没有差异。然而，事后分析表明，T1 期 MCAV 与 T2 期和 T3 期 HRV 和 CVCi 呈正相关。T1 期较高的 MCAV 也与脑震荡运动员无症状 T2 期的认知评分较高有关。因此，我们的结果表明，脑震荡后急性恢复期 ANS 失调。CBF 的差异可能是脑震荡后临床症状和功能结果异质性的潜在原因之一，需要进一步研究来验证这一发现。
