Churchill Nathan W, Hutchison Michael G, Graham Simon J, Schweizer Tom A
Brain Health and Wellness Research Program, St. Michael's Hospital, Unity Health Toronto, Ontario, Canada.
Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Unity Health Toronto, Ontario, Canada.
Neurology. 2025 Apr 8;104(7):e213374. doi: 10.1212/WNL.0000000000213374. Epub 2025 Mar 12.
Medical clearance for return to play (RTP) after sports-related concussion is based on clinical assessment. It is unknown whether brain physiology has entirely returned to preinjury baseline at the time of clearance. In this longitudinal study, we assessed whether concussed individuals show functional and structural MRI brain changes relative to preinjury levels that persist beyond medical clearance. Secondary objectives were to test whether postconcussion changes exceed uninjured brain variability and to correlate MRI findings with clinical recovery time.
For this prospective observational study, healthy athletes without a history of psychiatric, neurologic, or sensory-motor conditions were recruited from a single university sport medicine clinic. Clinical and MRI data were collected at preseason baseline, and those who were later concussed were reassessed at 1-7 days after injury, RTP, 1-3 months after RTP, and 1 year after RTP. A demographically matched control cohort of uninjured athletes was also reassessed at their subsequent preseason baseline. Primary outcomes were postconcussion changes in MRI measures of cerebral blood flow (CBF), white matter mean diffusivity (MD), and fractional anisotropy (FA), evaluated using mixed models. Secondary outcomes were group differences in MRI change scores and correlations of change scores with days to RTP.
Of the 187 athletes enrolled in the study, 25 had concussion with follow-up imaging (20.3 ± 1.5 years, 56% male, 44% female) and were compared with 27 controls (19.7 ± 1.8 years, 44% male, 56% female). Concussed athletes showed statistically significant changes from baseline, including decreased frontoinsular CBF (mean and 95% CI -8.97 [-12.80, -5.01] mL/100 g/minute, z = -4.53), along with increased MD (1.94 × 10 [1.26, 2.69] × 10, z = 5.48) and reduced FA (-7.30 × 10 [-9.80, -5.05] × 10, z = -6.07) in the corona radiata and internal capsule. Effects persisted beyond RTP, although only CBF changes exceeded longitudinal variability in controls. For participants with longer recovery periods, significantly greater changes in medial temporal CBF were also seen (ρ = 0.64 [0.44, 0.81], z = 6.80).
This study provides direct evidence of persistent postconcussion changes in CBF and white matter at RTP and up to 1 year later. These results support incomplete recovery of brain physiology at medical clearance, with secondary analyses emphasizing the sensitivity of CBF to clinical recovery.
与运动相关的脑震荡后恢复运动（RTP）的医学许可基于临床评估。目前尚不清楚在获得许可时脑生理功能是否已完全恢复到受伤前的基线水平。在这项纵向研究中，我们评估了脑震荡患者相对于受伤前水平是否存在功能和结构MRI脑变化，且这些变化在医学许可后仍持续存在。次要目的是测试脑震荡后的变化是否超过未受伤大脑的变异性，并将MRI结果与临床恢复时间进行关联。
在这项前瞻性观察研究中，从一所大学运动医学诊所招募了没有精神、神经或感觉运动疾病史的健康运动员。在季前赛基线时收集临床和MRI数据，那些后来发生脑震荡的运动员在受伤后1 - 7天、RTP时、RTP后1 - 3个月以及RTP后1年进行重新评估。一个在人口统计学上匹配的未受伤运动员对照队列也在其随后的季前赛基线时进行重新评估。主要结局是使用混合模型评估的脑震荡后大脑血流量（CBF）、白质平均扩散率（MD）和分数各向异性（FA）的MRI测量值变化。次要结局是MRI变化评分的组间差异以及变化评分与RTP天数的相关性。
在参与研究的187名运动员中，25名发生脑震荡并接受了随访成像（年龄20.3±1.5岁，男性56%，女性44%），并与27名对照者（年龄19.7±1.8岁，男性44%，女性56%）进行比较。脑震荡运动员与基线相比显示出统计学上的显著变化，包括额岛叶CBF降低（平均值和95%可信区间 - 8.97 [- 12.80, - 5.01] mL/100 g/分钟，z = - 4.53），同时放射冠和内囊的MD增加（1.94×10 [1.26, 2.69]×10，z = 5.48）以及FA降低（ - 7.30×10 [- 9.80, - 5.05]×10，z = - 6.07）。这些影响在RTP后仍持续存在，尽管只有CBF变化超过了对照组的纵向变异性。对于恢复期较长的参与者，内侧颞叶CBF也有显著更大的变化（ρ = 0.64 [0.44, 0.81]，z = 6.80）。
本研究提供了直接证据，表明在RTP时以及之后长达1年，脑震荡后脑血流量和白质存在持续变化。这些结果支持在医学许可时脑生理功能未完全恢复，二次分析强调了CBF对临床恢复的敏感性。
