MSD Manual

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Kee Kiat Yeo

, MD, Harvard Medical School

Reviewed/Revised May 2023
Topic Resources

The central nervous system is made up of the brain and spinal cord. Medulloblastomas are rapidly growing brain tumors that develop in the cerebellum (the part of the brain that helps control coordination and balance). All medulloblastomas are cancerous (malignant).

  • The cause of medulloblastomas is not known.

  • Children may have frequent vomiting, trouble with balance, headaches, nausea, lethargy, or double vision.

  • Diagnosis usually involves an imaging test, biopsy, and a spinal tap.

  • Treatment is surgery, chemotherapy, and radiation therapy.

  • The prognosis depends on whether the cancer is average risk or high risk.

Medulloblastomas are one of the most common malignant brain tumors in children. These tumors tend to occur in children who are 3 to 4 years old or 8 to 10 years old, but they can occur in infants and throughout adolescence.

Medulloblastomas develop in the part of the brain that controls coordination and balance (cerebellum), which is located in the back of the brain below the cerebrum.

Medulloblastomas tend to spread to other parts of the brain and to the spinal cord. Very rarely, they spread to other parts of the body.

What causes medulloblastomas is unclear. They sometimes occur in people with certain hereditary disorders (such as Gorlin syndrome or Turcot syndrome).

Symptoms of Medulloblastomas

Symptoms of medulloblastoma are typically related to increased pressure within the skull (intracranial pressure) and dysfunction of the cerebellum.

Symptoms may include vomiting, clumsiness, walking unsteadily, or trouble maintaining balance. Children also may have headaches, nausea, lethargy, and double vision.

Diagnosis of Medulloblastomas

  • Magnetic resonance imaging (MRI)

  • Biopsy or often surgery to remove the entire tumor

  • Spinal tap

To make the diagnosis of medulloblastoma, doctors do an MRI Magnetic Resonance Imaging (MRI) Magnetic resonance imaging (MRI) is a type of medical imaging that uses a strong magnetic field and very high frequency radio waves to produce highly detailed images. During an MRI, a computer... read more Magnetic Resonance Imaging (MRI) with a contrast agent Radiographic Contrast Agents Radiographic contrast agents are substances used to distinguish between internal structures in medical imaging, such as various types of x-rays and magnetic resonance imaging (MRI). During imaging... read more (a substance that makes the structures clearer to see on imaging tests) to look for a tumor. Then, they take a sample of tissue from the tumor and examine it under a microscope (biopsy). They may also do special genetic tests on the sample to help with diagnosis and treatment. Usually, instead of removing just part of the tumor for the sample, the entire tumor is surgically removed and sent for examination.

To determine whether the tumor has spread, doctors do MRI of the spine and a spinal tap (lumbar puncture—see figure ). The spinal tap is done to obtain cerebrospinal fluid for examination under a microscope to look for cancer cells.

After surgery is done, doctors do another MRI to see whether the tumor has been completely removed. The results of these tests help doctors determine whether the tumor is average risk or high risk.

Risk is average if

  • All or almost all of the tumor can be removed during surgery.

  • The tumor has not spread to other parts of the brain, the spinal fluid, or elsewhere in the body.

Risk is high if

  • A large amount of tumor cannot be removed during the surgery.

  • The tumor has spread to other parts of the brain, the spinal cord, or elsewhere in the body.

In recent years, genetic testing results have been shown to have an impact on outcome and risk.

Treatment of Medulloblastomas

  • Surgery, radiation therapy, and chemotherapy

Prognosis for Medulloblastomas

How well children do after treatment generally depends on whether they are categorized as having an average-risk or high-risk tumor.

For children older than 3 years, the chances of surviving cancer-free for 5 years is about 80% if the tumor is average risk and about 60 to 70% if it is high risk.

For children 3 years old and younger, outcome is harder to predict, but overall survival is poor. In about 40% of these children, the tumor has spread at the time of diagnosis. In addition, radiation therapy is typically delayed or not done in this age group. Children who survive are at risk of severe long-term mental deficits. For example, intellectual development is more likely to be affected, and they may have difficulty learning, remembering, and making decisions.

Certain types of medulloblastomas have a very good prognosis, with 90 to 100% overall survival.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

  • American Cancer Society: If Your Child Is Diagnosed With Cancer: A resource for parents and loved ones of a child who has cancer that provides information about how to cope with some of the problems and questions that come up just after a child is diagnosed

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