Female athletes who have suffered at least one concussion showed structural differences in the corpus callosum, the structure that connects the two hemispheres of the brain, compared to unconcussed female athletes and other women.
A study by Canadian researchers of brain images six months after concussion that suggested long-term changes in the corpus callosum, mainly in the region where it projects to the prefrontal and premotor areas of the brain.
Previous research had shown long-term abnormalities in the white matter (WM) tracts of male athletes. The corpus callosum (CC) and corticospinal tract (CST) have been shown to be particularly vulnerable to concussion, which may be related to abnormal interhemispheric functional connectivity and motor impairments. These anatomical pathways, however, have not been investigated in female athletes despite the functional significance of the CC and CST to adequate sports performance.
In the article “Long-Term Abnormalities in the Corpus Callosum of Female Concussed Athletes” published in the Journal of Neurotrauma, coauthors Emilie Chamard, Genevieve Lefebvre, Maryse Lassonde, and Hugo Theoret, University of Montreal and CHU-Sainte-Justine, Montreal, Canada, used diffusion tensor imaging to examine of the corticopsinal tract and corpus callosum of the study participants. They found no significant differences between the groups of women in the corticospinal tract, but reported evidence of microstructural changes and a lower volume of white matter fibers in the corpus callosum.
For the study, the Canadian researchers compared eight healthy, unconcussed female athletes (soccer, hockey) with 10 female athletes (soccer, hockey, water polo) 6 months post-concussion. Diffusion tensor imaging (DTI) of the CC and CST showed no significant differences between groups within the CST but revealed differences between groups in the CC. A lower volume of WM fibers was found in the region projecting to the premotor and supplementary motor areas. Finally, lower axial diffusivity (AD) was observed in the CC area projecting mainly to the parietal and temporal area (t = 2.23; p = 0.041). Long-term alterations in the CC of female athletes appear to affect mostly the anterior part of the CC projecting to the prefrontal and premotor areas.
The above image shows the Sagittal view of the callosal fiber tracts from a control subject overlaid over her individual reference image. Representation of the divisions of the corpus callosum comprising bundles projecting to the prefrontal lobe, premotor and supplementary motor areas, primary motor cortex, primary sensory cortex, parietal and temporal lobe, and occipital lobe.
John T. Povlishock, PhD, Editor-in-Chief of Journal of Neurotrauma and Professor, Medical College of Virginia Campus of Virginia Commonwealth University, Richmond, said the study was important from several perspectives.
“It reinforces the need to analyze gender-specific responses following TBI, while emphasizing that concussive injury in female athletes elicits regionally specific changes in the corpus callosum, which include prefrontal connections, a finding not routinely discussed in the literature.”
Long-Term Abnormalities in the Corpus Callosum of Female Concussed Athletes, Journal of Neurotrauma, July 2016. Available here. DOI: 10.1089/neu.2015.3948