DTI-Fiber Tractography of Cerebellar Pathways can be Related to Neurocognitive Deficits in Children with Posterior Fossa Tumors

Background/Objectives: Lesions of the cerebellum fibers may result in cognitive function impairments in brain tumor survivors. A more differentiated identification of neu- roanatomical structures contributing to the extent of this damage is needed. We examined the relationship between long-term cognitive dysfunction and alteration of cerebel- lar pathways using diffusion tensor imaging (DTI) and tractography. Design/Methods: DTI-based tractography was performed in patients with posterior fossa tumors. Spinocerebellar (SC), dento-rubro-thalamo-cortical (DRTC), fronto-ponto- cerebellar (FPC), parieto-ponto-cerebellar (PPC), occipito- ponto-cerebellar (OPC) and temporo-ponto-cerebellar (TPC) tracts were analyzed concerning fractional anisotropy (FA) and volumetric measurements. Cognitive outcome was assessed with the Developmental Neuropsychological scale (NEPSY). The correlations between NEPSY scores and fiber tracts were tested with linear regression analysis. Results: Seven patients with cerebellar tumor were included (median age 63 months - IQR: 39-80). All children had com- plete surgery: 2/7 (29%) had medulloblastoma, and 5/7 (71%) pilocytic astrocytoma. Median IQ was 83.5 (74.75-83.87) and correlation was found with right SC (R2 for number of fibers 0.50; volume 0.90) and DRTC tracts (R2 for volume 0.58; FA 0.52). Patients showed worst performance in the follow- ing items: attention, correlated with right OPC (R2 for num- ber of fibers 0.53; FA -0.86) and PPC tracts (R2 of number of fibers 0.59; volume 0.61; FA 0.52); memory for design, related to left FPC tract (R2 of number for fibers 0.63; vol- ume -0.63); memory for names, correlated with right DRTC tract (R2 for number of fibers 0.85; volume 0.90); visuospa- tial function, inversely correlated with left OPC tract (R2 of number of fibers -0.81; volume -0.66); and social perception, correlated with left SC (R2 of number for fibers 0.55; volume 0.53) and right PPC tracts (R2 of number for fibers 0.90; vol- ume 0.69). Conclusions: DTI may be useful to identify relevant struc- tures of the cerebellar pathway and possibly avoid surgically induced long-term neurological sequelae.