They develop in the cerebellum, in a part of the brain called the posterior fossa, but may spread to other parts of the brain, and very rarely to other parts of the body. Medulloblastomas are usually found in children, particularly between the ages of three and eight. The tumour is more common in males than females. They can also occur in adults but are extremely rare. Like most brain tumours the cause of medulloblastoma is unknown.
Research continues into finding possible causes.
This may be due to a blockage in the ventricles of the brain which leads to a build up of CSF or by swelling around the tumour itself. Raised intracranial pressure can cause headaches, vomiting and visual disturbances. Vomiting is common first thing in the morning. Children often appear lethargic and irritable. Changes in personality and behaviour may also be noticed.