Gender-Associated Variation in Morphometric Analysis of the Corpus Callosum: A Hospital-Based Cross-Sectional Study...

The corpus callosum (CC) is a pivotal commissural bundle that facilitates interhemispheric connectivity and contributes to cognitive functions, learning, memory, thinking, visual acuity, executive functions, and behaviour. Precise morphometric dimensions of the CC are imperative for informed surgical interventions, stereotactic approaches, and callosotomy for intractable epilepsy. However, the existing literature lacks consensus on gender- and age-related variations in the CC, with limited representation from Southeast Asia and India. This study aimed to define gender- and age-related variations in CC morphology and establish reliable baseline parameters for clinical and research applications.

This retrospective, hospital-based cross-sectional study was conducted in the Department of Anatomy. The study included 200 brain magnetic resonance imaging scans, comprising 55% males and 45% females. The brain morphometric parameters such as distance between the anterior frontal pole and the posterior occipital pole (AB), distance between the anterior frontal pole and the anteriormost part of the genu (AC), distance between the anteriormost part of genu to posteriormost part of the splenium (CD) and the distance between the posterior occipital pole and the posteriormost part of the splenium (BD). The CC was divided into five equal subregions along its principal axis. Thickness of the CC was measured at the genu (GL) and at four equidistant body segments (B1, B2, B3, and B4) from proximal to distal. In addition, splenium thickness (SL), callosal height (CC ht), and the splenium index (SI) were also recorded. Measurements were compared across age groups and between genders.

The mean age was 32.93 years, with a similar sex distribution across groups; females showed slightly lower mean ages in older cohorts. Mean CC parameters were comparable between sexes. Males showed slightly higher values in overall AB, AC, and DB. Conversely, females exhibited marginally greater callosal body segmental thicknesses (B1-B4) and CC ht. Sex-wise comparisons using an independent t-test showed no major differences, except for significant variation in splenial length (1-20 years; p = 0.048) and CC ht (21-40 years; p = 0.009). A moderate positive association was observed between CD and AB, as well as between consecutive body segments (B1-B2 and B2-B3). A strong negative correlation was noted between the SI and SL (r = -0.773). Age-related differences were mainly observed in AB, CD, and SL. AB increased significantly from 1-20 to 21-40 years (p = 0.003). CD showed highly significant increases from 1-20 to both 21-40 and 41-60 years (p < 0.001), and a minor difference with 61-80 years (p = 0.01). SL consistently decreased in older groups compared with 1-20 years. SI showed only a marginal change (p = 0.05), indicating overall stability. These findings reflect maturation-related changes predominantly in the anterior and posterior callosal regions.

The study demonstrated measurable gender- and age-related differences in CC, with females showing greater callosal length, thickness, and splenial dimensions, while males exhibited larger brain length and wider interhemispheric distances. Significant correlations among callosal segments and overall brain length further highlighted structural interrelationships. These findings contribute valuable population-specific reference data for anatomical and neuroimaging studies.