ORIGINAL RESEARCH PEDIATRICS Time-Dependent Structural Changes of the Dentatothalamic Pathway in Children Treated for Posterior

BACKGROUND AND PURPOSE: Injury to the dentatothalamic pathway that originates in the cerebellum has been suggested as a mechanism for neurologic complications in children treated for posterior fossa tumors. We hypothesized that time-dependent changes occur in the dentatothalamic pathway. MATERIALS ANDMETHODS: Diffusion tensor evaluation was performed in 14 children (median age, 4.1 years; age range, 1–20 years) who underwent serial MR imaging at 3T as part of routine follow-up after posterior fossa tumor resection with or without adjuvant therapy. Tensor metrics were obtained in the acute (1 week), subacute (1 to 6 months), and chronic (6 months) periods after surgery. We evaluated the following dentatothalamic constituents: bilateral dentate nuclei, cerebellar whitematter, and superior cerebellar peduncles. Serial dentate nuclei volumes were also obtained and compared with the patient’s baseline. RESULTS: Themost significant tensor changes to the superior cerebellar peduncles and cerebellar white matter occurred in the subacute period, regardless of the tumor pathology or therapy regimen, with signs of recovery in the chronic period. However, chronic volume loss and reducedmean diffusivity were observed in the dentate nuclei and did not reverse. This atrophy was associated with radiation therapy and symptoms of ataxia. CONCLUSIONS: Longitudinal diffusion MR imaging in children treated for posterior fossa tumors showed time-dependent tensor changes in components of the dentatothalamic pathway that suggest evolution of structural damage with inflammation and recovery o