Medulloblastomas are a type of brain tumor that primarily occurs in children. They develop in the cerebellum, the part of the brain responsible for coordination and balance. These tumors are classified as primitive neuroectodermal tumors (PNETs) and can spread to other parts of the central nervous system. Symptoms of medulloblastomas may include headaches, nausea, vomiting, and difficulties with balance or coordination. Diagnosis typically involves imaging tests like MRI scans, and treatment often includes a combination of surgery, radiation therapy, and chemotherapy to remove or shrink the tumor and prevent its recurrence.