A revised visual grading scale of the cavum septi pellucidi in contact-collision sport athletes with repetitive head impacts

The cavum septi pellucidi (CSP), a persistent separation between the septal leaflets in the brain, is found among athletes exposed to repetitive head impacts (RHI), yet existing grading systems may inadequately capture anatomical variants. This study presents a revised CSP grading scale for RHI-exposed populations. This cross-sectional study included 170 former American football players and 54 unexposed asymptomatic controls, all males aged 45-74, who underwent magnetic resonance imaging. Two blinded raters independently applied a revised 5-point CSP grading scale, with reliability assessed using Cohen’s κ. CSP length and volume were quantified, and associations with cumulative head impact exposure were examined. Multivariable ordinal logistic regression compared CSP grades between former football players and controls. Following consensus ratings, former football players demonstrated significantly greater odds of being classified into a higher CSP grade than unexposed controls (OR = 4.41, [95% CI: 2.34, 8.31], p < 0.001). CSP length and volume increased across CSP grade (both p < 0.001), supporting the anatomical validity of the revised grading system. Among former football players, estimated cumulative linear and rotational head impact exposures differed significantly across CSP grades (Kruskal–Wallis p = 0.007 and p < 0.001, respectively), with Grade 4 showing greater exposure than Grade 0. A revised CSP grading scale incorporating posterior variants shows high inter-rater reliability and concordance with quantitative measures in RHI-exposed athletes. More severe CSP morphology was associated with greater cumulative biomechanical exposure, and the revised grading system enables consistent classification of CSP morphology for future RHI studies. A small fluid-filled space in the brain called the cavum septi pellucidi (CSP) is often seen on MRI scans of athletes with histories of repeated head impacts (RHI). However, existing visual grading systems may miss forms of CSP, especially when it extends toward the back of the brain. We developed a revised 5-point MRI grading scale and tested it in 170 former American football players and 54 unexposed controls without a history of RHI. The new scale matched precise CSP size measurements and showed strong rater agreement. More severe CSP grades were associated with lifetime head-impact exposure, suggesting that RHI may contribute to these brain changes and serve as a better tool for long-term brain health research. Mirmajlesi, Stearns, Szekely et al. present a revised cavum septum pellucidum grading scale for individuals exposed to repetitive head impacts. They find that cavum septum pellucidum volume and length increased with grade, and that more severe grades were associated with greater repetitive head impact exposure.