Concussion in Female Athletes of Contact Sports: A Scoping Review.

Background: Recent studies have described higher incidences of concussion, with more severe symptoms and worse outcomes in female athletes compared with male athletes. Purpose: To compile current knowledge about sex-specific differences in incidence, biomechanics, biomarkers, imaging, and outcomes of concussion in athletes participating in contact sports to better understand which fields should be explored in more detail. Study Design: Scoping review; Level of evidence, 3. Methods: The PubMed database was searched for articles published between January 2000 and November 2020 using the Medical Subject Headings terms "craniocerebral trauma" and "brain concussion" combined with the contact sports "football,""soccer,""hockey," and "boxing." Eligibility criteria were based on the recommendations of the Scottish Intercollegiate Guidelines Network. It focused on sex-specific differences within 5 major topics: (1) epidemiology, (2) biomechanics, (3) biomarkers, (4) imaging, and (5) specific concussion outcome variables, including neurocognitive performance, injury severity, and behavioral and psychological symptoms. Results: A total of 22 studies were included. Eight studies investigated the incidence of concussion, with 4 of the 8 finding a significantly higher incidence rate for female versus male athletes. Six studies that focused on biomechanics found that female athletes received fewer impacts with lower magnitudes. One study addressed biomarkers, showing that S100 calcium-binding protein B and neuron-specific enolase were increased after a game in female athletes, and the level of increase was similar to the changes found in male athletes. Based on the 3 imaging studies, affected brain tissue was greatest in areas associated with tau pathology in chronic traumatic encephalopathy. One study showed a lower hypointensity burden index after a season of ice hockey for female athletes, while another study showed more regions with white matter alterations. Seven studies examined concussion outcomes, with 4 studies showing more severe neuropsychological deficits; in addition, female athletes reported more and worse symptoms than male athletes. Conclusion: The results of this review indicated that female athletes had a higher risk of sustaining a concussion, although they received fewer impacts with lower magnitudes than male athletes. Biomarkers were able to be used equally for both sexes. Female athletes also had a higher neuropsychological deficit and increasingly worse symptoms after a concussion.