By Louise M. Klebanoff, MD
Assistant Professor of Clinical Neurology, Weill Cornell Medical College
Dr. Klebanoff reports no financial relationships relevant to this field of study.
Repeated subconcussive injuries to the brain, such as “heading” the ball in soccer, result in more severe injury and slower recovery in women compared to men.
Rubin TG, Catenaccio E, Fleysher R, et al. MRI-defined white matter microstructural alteration associated with soccer heading is more extensive in women than men. Radiology 2018;289:478-486.
Soccer is a sport with a known risk for concussion from player-to-player collision, falls, and repeated “heading” — using the head to deflect the ball in play. Although heading-related impacts have been considered subconcussive, heading is associated with acute central nervous system symptoms. Cumulative heading is associated with cognitive dysfunction and microstructural alteration of white matter on imaging from diffusion-tensor imaging (DTI), similar to that seen with traumatic axonal injury. Female athletes are at greater risk than male athletes for poor outcome after acute traumatic brain injury, including concussion; it is uncertain if this is due to women being more likely to report symptoms when compared with men or is due to a different pathophysiological response to trauma. Neuroimaging can provide an objective means to characterize subclinical variation in brain structure and functioning following head trauma.
To test the hypothesis that DTI would reveal sex-based differences in the association of repetitive head trauma by comparing the microstructural alteration of white matter in the brain, Rubin et al conducted a prospective study comparing female and male amateur soccer players. Each female athlete was paired with a male athlete within two years of her age and with the closest match with respect to reported 12-month heading exposure. A final cohort of 49 men and 49 women, with a median total soccer heading events per year of 487 and 469, respectively, completed the study.
Investigators performed whole-brain MRI with DTI on each patient. They performed whole-brain voxel-wise analysis of white matter fractional anisotropy (FA) using the Automatic Registration Toolbox VANCOVA module to fit a linear regression for FA. Among men, the authors identified three regions in which a greater number of heading events was associated with significantly lower FA: the genu and splenium of the corpus callosum and the pons. In women, the authors identified seven regions in which greater heading was associated with significantly lower FA: the genu of the corpus callosum, left occipital, right parietal and right orbitofrontal white matter, left superior longitudinal fasciculus, right cingulum and right cerebral peduncle. In men, the left temporal white matter showed a significantly higher FA with greater heading exposure. In women, a single location in the left frontal white matter showed a significantly higher FA with greater heading exposure.
Women consistently showed a greater number and volume of regions with a significant association of heading with lower FA. Heading also was associated with changes in radial diffusivity, mean diffusivity, and axial diffusivity in both men and women. Greater heading exposure was associated with lower white matter axial diffusivity over great volume in men than in women.
COMMENTARY
This study provides preliminary radiographic evidence of changes in the brain microstructure to support the observed differences between men and women in response to repeated heading. Women may be more sensitive than men to the effects of heading at the level of tissue microstructure, with FA the most prevalent indicator of microstructural alteration. Greater heading exposure was associated with lower FA. Lower FA may be indicative of chronic traumatic axonal injury. By identifying risk factors for the development of cumulative injury, including gender, one potentially could develop prevention techniques before long-term sequela develop.
