A pilot study will be performed. We will perform fMRI and DTI in children before and after surgery for posterior fossa brain tumors. Each subject will receive the standard of care for their brain tumors in terms of surgical resection, radiation therapy and/or chemotherapy.

When possible, the subject will undergo a post operative fMRI/ DTI scan as well as clinical language testing. If the subject develops CMS, the second fMRI will be performed as soon as possible. Some subjects may be severely impaired or have difficulty performing fMRI and clinical language testing tasks. In these instances, the fMRI and language testing may not be performed, or we may choose to perform resting state or passive fMRI tasks instead.

in young children at risk for developing CMS after posterior fossa brain tumor resection. Age appropriate language functional MRI tasks targeting the cerebellar language centers will be performed in children before surgery and correlated with formal neuropsychological and language testing. The fMRI will be repeated after surgery. If ≥5 of the 7 subjects successfully complete ≥60% of the functional imaging tests, we will determine the pilot study to be successful and then pursue further study.

in subjects who develop CMS after brain tumor resection. Injury to cerebro-cerebellar tracts such as the dentatothalamocortical tracts has been implicated in the development of CMS. We propose studying the proximity between important language white matter paths and the surgical intervention before surgery. DTI: Measurements of DTI parameters (e.g., fractional anisotropy, apparent diffusion coefficient) of cerebellar and cerebro-cerebellar white matter tracts on the preoperative scan