A prospective study of corpus callosum regional volumes and neurocognitive outcomes following cranial radiation for pediatric brain tumors.

PURPOSE/OBJECTIVE(S): Cranial radiation therapy (CRT) may disrupt the corpus callosum (CC), which plays an important role in basic motor and cognitive functions. The aim of this prospective longitudinal study was to assess changes in CC mid-sagittal areas, CC volumes, and performance on neuropsychological (NP) tests related to the CC in children following CRT.

MATERIALS/METHODS: Twelve pediatric patients were treated with CRT for primary brain malignancies. Thirteen age-matched healthy volunteers served as controls. Brain MRIs and NP assessment emphasizing motor dexterity, processing speed, visuomotor integration, and working memory (visual and verbal) were performed at baseline and at 6, 15, and 27 months following completion of CRT. Linear mixed effects (LME) analyses were used to evaluate patient NP performance and changes in regional CC volumes (genu, anterior body, mid-body, posterior body, and splenium) and mid-sagittal areas over time and with radiation doses, correcting for age at CRT start.

RESULTS: The mean age at CRT was 9.41 (range 1.2-15.7) years. The median prescription dose was 54 (range 18-59.4) Gy. LME analysis revealed a significant decrease in overall CC volumes over time (p < 0.00001), with no overall effect of radiation dose. Analysis of individual CC regions demonstrated a significant decrease in all regional volumes over time (p < 0.00001) in patients, with no effect of radiation dose. Only in the splenium was there a trend toward a dose-dependent effect (p = 0.093). Patients had significantly reduced NP performance across visits-most notably in motor dexterity and visual working memory (both p < 0.0001).

CONCLUSIONS: These prospective data demonstrate a significant decrease in CC regional volumes after CRT, with associated decline in neurocognitive function, most notably in manual dexterity, attention, and working memory. Further prospective study of larger cohorts of patients is needed to establish the relationship between CRT dose, neuroanatomical, and functional changes in the CC.