They are by far the most common childhood brain tumors, and they account for up to 20% of brain tumors in children, usually aged 3 to 8 years old, and more common in males than females. It is a tumor of embryonic origin, which start in the earliest of brain cells. It is a malignant tumor that usually spreads through the cerebrospinal fluid to many other areas of the brain and the spinal cord.
Medulloblastoma usually appears near the cerebellum, in an area called posterior fossa. In this area, there is a structure called fourth ventricle, which drains cerebrospinal fluid. When this structure is blocked by the growth of the tumor, it causes a condition called hydrocephalus, which increases the pressure of the cerebrospinal fluid and causes massive headaches. Children may also report feeling too tired, and they have balance problems, nausea, vomiting, blurry vision, and abnormal eye movements.