Medulloblastoma is a form of brain cancer that generally originates between the brain stem and the cerebellum. When it grows, it can block the flow of cerebro-spinal fluid and can mestasisize throughout the central nervous system. It generally affects people under the age of 20 and 40% of patients are diagnosed before the age of five. The symptoms of a medulloblastoma can easily be mistaken for migraine or even a chronic digestive tract disorder. However, the tumor will show up clearly on an MRI.