NCOG-09. Lesions of the corpus callosum and neuropsychological test results in patients with Neurofibromatosis Type I (NF1)

OBJECTIVE Investigate the impact of focal areas of signal intensity (FASI) and gliomas located in the corpus callosum (CC) on neuropsychological profiles of NF1 patients. Background: NF1 is a genetic disorder associated with nervous system tumors, cognitive impairments, and often a leftward IQ shift. Brain MRIs often show T2 hyperintensities called FASI. While CC lesions have been associated with cognitive deficits in the general population, their impact in large NF1 cohorts remains understudied. Design/ METHODS We performed a retrospective chart review of 63 NF1 patients (aged 4 to 25 years) who underwent neuropsychological testing. Patients with CC gliomas or FASI were identified and their results were compared across multiple domains including FSIQ, attention, language, academic, visual, and executive functioning. RESULTS Among 63 patients, 10 had CC FASI or gliomas. Of the remaining 53, 33.9% had FASI and 54.7% had gliomas of other locations, while 11.3% had no lesions. Overall FSIQ scores were not significantly different between NF1 patients with a CC lesion versus lesions elsewhere, or between patients with and without CC lesions. However, patients with CC lesions had significantly lower verbal comprehension index scores than those without (8.5% vs. 19.0%, p=0.028). Those with CC FASI had significantly lower Verbal Comprehension (7% vs 55%, p=0.046), Visual-Spatial (12% vs 48%, p=0.05), Working Memory (21% vs 61%, p=0.046), and Beery VMI (3% vs 22.5%, p=0.02) scores than those without lesions. CONCLUSIONS While CC FASI or gliomas do not significantly impact NF1 patients’ overall FSIQ, they are associated with lower verbal comprehension, visual-spatial skills, and working memory index scores. Scientific Relevance: This study highlights the previously underexplored impact of CC lesions on neurocognitive function in NF1, emphasizing the importance of lesion location in clinical assessments.