Corpus callosum structure and auditory interhemispheric transfer in spina bifida myelomeningocele.

Objective: Maldevelopment of the posterior corpus callosum is common in spina bifida myelomeningocele (SBM) due to hydrocephalus-related hypoplasia and congenital partial hypogenesis. This study examined the relations of macro- and microstructural integrity of the interhemispheric temporal tract in SBM and auditory interhemispheric transfer using consonant-vowel dichotic listening.

Method: We collected T₁-weighted and diffusion tensor imaging data from 46 individuals with SBM and 15 typically developing individuals. Probabilistic tractography was used to isolate the interhemispheric white matter connecting auditory processing regions in both hemispheres. Interhemispheric transfer was assessed with a dichotic listening task.

Results: Although the typically developing group and the group with SBM showed the normative right-ear advantage, fewer participants showed a right-ear advantage in the group with SBM. The absence of the right-ear advantage was largely in the subgroup with hypogenesis of the splenium or severe posterior hypoplasia. Sex, anterior commissure cross-sectional area, and number of shunt pathways visible on magnetic resonance imaging predicted right-ear superiority.

Conclusions: Interhemispheric transfer is disrupted in individuals with SBM and hypogenesis or severe hypoplasia of the posterior corpus callosum. Preservation of interhemispheric transfer is related to expected connections through the posterior corpus callosum and possibly compensatory pathways in the anterior commissure. (PsycInfo Database Record (c) 2024 APA, all rights reserved).