Medulloblastoma (Childhood Brain Cancer)

Medulloblastoma is the most common cancerous brain tumor in children. It starts in the cerebellum, the part of the brain that controls balance and movement. These tumors grow quickly (grade IV) and can spread through the cerebrospinal fluid (CSF), the fluid that surrounds the brain and spinal cord. About 400 to 500 children are diagnosed each year in the United States.

Types & Stages

All medulloblastomas are grade IV tumors. Doctors divide them into four subtypes based on their genetic features:

• WNT-activated: The least common (about 10 percent) with the best outlook. Usually seen in older children and teens. Rarely spreads.
   
• SHH-activated: About 30 percent of cases. Most often found in infants and adults. Tends not to spread.
   
• Group 3: About 25 percent of cases. More common in boys and younger children. More likely to spread.
   
• Group 4: The most common (about 35 percent). Seen at all ages but rarely in infants. More common in boys and often spreads.

Sign & Symptoms

Common symptoms may include:

• Headaches, often in the morning or at night
• Nausea and vomiting
• Trouble walking or keeping balance (ataxia)
• Dizziness or double vision
• Unusual eye movements (nystagmus) or head bobbing
• Tiredness or confusion
• Buildup of fluid on the brain (hydrocephalus)

Diagnosis

Diagnosis may involve:

• Neurological exam
• MRI or other imaging tests
• Cerebrospinal fluid testing such as a spinal tap

Treatment

Treatment options may include:

• Surgery to remove as much of the tumor as safely possible and relieve pressure inside the skull
• Radiation therapy, including proton therapy for more targeted treatment
• Chemotherapy, given through a vein (IV) or by mouth

Causes & Risk Factors

The exact cause is unknown. Possible risk factors include:

• Age (most common in children)
• Inherited syndromes such as Gorlin syndrome, Li-Fraumeni syndrome, Turcot syndrome, Fanconi anemia or Rubinstein-Taybi syndrome

Screening

There is no routine screening for medulloblastoma. Diagnosis depends on noticing symptoms and getting a prompt medical evaluation.