Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital/Harvard Medical School, Boston, Massachusetts;
J Neurosurg. 2014 Apr;120(4):873-81. doi: 10.3171/2013.12.JNS132090. Epub 2014 Feb 4.
Concussion is a common injury in ice hockey and a health problem for the general population. Traumatic axonal injury has been associated with concussions (also referred to as mild traumatic brain injuries), yet the pathological course that leads from injury to recovery or to long-term sequelae is still not known. This study investigated the longitudinal course of concussion by comparing diffusion MRI (dMRI) scans of the brains of ice hockey players before and after a concussion.
The 2011-2012 Hockey Concussion Education Project followed 45 university-level ice hockey players (both male and female) during a single Canadian Interuniversity Sports season. Of these, 38 players had usable dMRI scans obtained in the preseason. During the season, 11 players suffered a concussion, and 7 of these 11 players had usable dMRI scans that were taken within 72 hours of injury. To analyze the data, the authors performed free-water imaging, which reflects an increase in specificity over other dMRI analysis methods by identifying alterations that occur in the extracellular space compared with those that occur in proximity to cellular tissue in the white matter. They used an individualized approach to identify alterations that are spatially heterogeneous, as is expected in concussions.
Paired comparison of the concussed players before and after injury revealed a statistically significant (p < 0.05) common pattern of reduced free-water volume and reduced axial and radial diffusivities following elimination of free-water. These free-water-corrected measures are less affected by partial volumes containing extracellular water and are therefore more specific to processes that occur within the brain tissue. Fractional anisotropy was significantly increased, but this change was no longer significant following the free-water elimination.
Concussion during ice hockey games results in microstructural alterations that are detectable using dMRI. The alterations that the authors found suggest decreased extracellular space and decreased diffusivities in white matter tissue. This finding might be explained by swelling and/or by increased cellularity of glia cells. Even though these findings in and of themselves cannot determine whether the observed microstructural alterations are related to long-term pathology or persistent symptoms, they are important nonetheless because they establish a clearer picture of how the brain responds to concussion.
脑震荡是冰球运动中的常见损伤，也是普通人群的健康问题。创伤性轴索损伤与脑震荡（也称为轻度创伤性脑损伤）有关，但从损伤到恢复或长期后遗症的病理过程尚不清楚。本研究通过比较脑震荡前后冰球运动员的弥散磁共振成像（dMRI）扫描，来研究脑震荡的纵向病程。
2011-2012 年冰球脑震荡教育项目（Hockey Concussion Education Project）在一个加拿大大学间体育赛季期间跟踪了 45 名大学级冰球运动员（包括男性和女性）。其中，38 名运动员在赛季前获得了可用于 dMRI 扫描的扫描结果。在赛季期间，11 名运动员遭受了脑震荡，其中 7 名脑震荡运动员在受伤后 72 小时内获得了可用于 dMRI 扫描的扫描结果。为了分析数据，作者进行了自由水成像，该方法通过识别与细胞组织相邻的白质中发生的变化相比，在细胞外空间中发生的变化来提高特异性，从而反映出比其他 dMRI 分析方法更高的特异性。他们使用个体化方法来识别空间异质性的变化，这在脑震荡中是预期的。
受伤前后对脑震荡运动员进行配对比较发现，在消除自由水后，轴向和径向扩散率降低，自由水体积减少，具有统计学意义（p < 0.05）。这些经自由水校正的测量值受含有细胞外水的部分容积的影响较小，因此更能反映脑内组织发生的过程。各向异性分数显著增加，但在消除自由水后，这一变化不再显著。
冰球比赛中的脑震荡会导致使用 dMRI 检测到的微观结构改变。作者发现的改变表明，细胞外空间减少，白质组织的扩散率降低。这一发现可能是由于肿胀和/或神经胶质细胞的细胞增多所致。尽管这些发现本身并不能确定观察到的微观结构改变是否与长期病理学或持续性症状有关，但它们仍然很重要，因为它们更清楚地说明了大脑对脑震荡的反应。
