The key finding
A comprehensive review of 74 studies published through May 2025 found that two specific brain structural differences — Chiari II malformation and abnormalities of the corpus callosum (the bridge connecting the brain’s two hemispheres) — are consistently linked to distinct cognitive challenges in people with myelomeningocele (MMC), the most common form of spina bifida. Chiari II malformation was associated with difficulties in visuospatial skills, executive function, and processing speed, while corpus callosum abnormalities, particularly in the back portions of this structure, were linked to slower communication between brain hemispheres and reduced cognitive processing speed. These relationships held true even when accounting for hydrocephalus (fluid buildup in the brain), suggesting these structural features independently shape long-term cognitive outcomes.
What the study looked like
Researchers conducted a systematic review searching four major medical databases (PubMed, Embase, Web of Science, and Cochrane Library) for studies published through May 2025. They included only studies that examined cognitive outcomes in individuals with MMC aged 5 years or older and that used neuroimaging (brain scans) to document Chiari II malformation or corpus callosum abnormalities. The final analysis included 74 studies encompassing children and young adults with MMC. The researchers assessed study quality using the Newcastle-Ottawa Scale and performed a narrative synthesis rather than statistical pooling, due to the varied methods used across different studies. The included research employed multiple imaging techniques, including standard MRI scans, Diffusion Tensor Imaging (DTI) to examine white matter microstructure, and functional MRI (fMRI) to assess brain network connectivity.
Why researchers think this happened
The review authors propose that these structural brain differences disrupt typical neural development and connectivity patterns. Chiari II malformation — where the lower part of the brain extends into the spinal canal — may compress or alter the development of brain regions critical for spatial reasoning, planning, and quick thinking. Corpus callosum abnormalities, especially when affecting the back portion (splenium), appear to slow the transfer of information between the brain’s left and right hemispheres, creating a bottleneck for integrated processing. Advanced imaging revealed microstructural changes in white matter tracts (the brain’s wiring) that correlated with cognitive test scores, suggesting that the quality of these connections matters as much as their presence. Functional imaging showed altered activity patterns in brain networks responsible for focused attention and coordinated thinking, indicating that MMC affects not just structure but also how brain regions communicate during mental tasks.
How to read this carefully
This review summarizes existing research rather than presenting new experimental data, meaning its conclusions are limited by the quality and consistency of the underlying studies. The researchers noted substantial variation across studies in imaging methods, cognitive tests used, and participant characteristics, which prevented statistical combination of results. Most studies were observational and cross-sectional (measuring people at one point in time), making it impossible to determine whether these brain differences cause cognitive challenges or simply occur alongside them. The review included participants ranging from age 5 to young adulthood, but developmental trajectories — how these relationships might change as children grow — remain unclear. Additionally, people with MMC often have multiple coexisting conditions, making it challenging to isolate the specific contribution of any single brain structure difference to cognitive outcomes.
What this means for everyday life
For families affected by spina bifida, this research suggests that understanding a child’s specific brain structure through imaging might help predict which cognitive areas may need extra support. Children with documented Chiari II features might benefit from targeted help with spatial tasks (like puzzles, reading maps, or geometry) and executive function skills (planning, organizing, flexible thinking), while those with corpus callosum differences might need more time to process complex information that requires coordinating both sides of the brain. The finding that these structural features independently affect cognition — separate from hydrocephalus — means that even children whose fluid levels are well-managed may still face specific learning challenges worth addressing early. Given these connections, it might be worth considering neuropsychological evaluation for children with MMC to identify their specific cognitive profile, allowing educators and therapists to tailor support strategies to each child’s brain architecture rather than applying one-size-fits-all approaches.