EXAMINATION OF FRONTAL AND PARIETAL TECTOCORTICAL ATTENTION PATHWAYS IN SPINA BIFIDA MENINGOMYELOCELE USING PROBABILISTIC DIFFUSION TRACTOGRAPHY

Abnormalities of the midbrain tectum are common, but variable, malformations in spina bifida meningomyelocele (SBM), and have been linked to neuropsychological deficits in attention orienting. The degree to which variations in tectum structure influence white matter (WM) connectivity to cortical regions implicated in attention processes is unknown. To assess relations of tectal structure and connectivity to frontal and parietal cortical regions, probabilistic diffusion tractography was performed on 106 individuals (80 SBM, 26 typically developing (TD)) using FSL’s probtracX to isolate anterior versus posterior tectocortical WM pathways. Results showed that those with SBM exhibited significantly reduced tectal volume, along with decreased fractional anisotropy (FA) in posterior but not anterior tectocortical WM pathways when compared to TD individuals. The group with SBM also showed greater within-subject discrepancies between frontal and parietal WM integrity compared to the TD group. Of those with SBM, qualitative classification of tectal beaking based on radiological review was associated with increased axial diffusivity across both anterior and posterior tectocortical pathways, relative to individuals with SBM and a normal appearing tectum. These results support previous volumetric findings of greater impairment to posterior versus anterior structures in SBM, and quantifiably relate tectal volume, tectocortical WM integrity, and tectal malformations in this population.