Medulloblastomas are rapidly growing brain tumors that develop in the cerebellum (the part of the brain that helps control coordination and balance). These tumors develop during childhood. All medulloblastomas are cancerous (malignant).
Children may have frequent vomiting, trouble with balance, headaches, nausea, lethargy, or double vision.
Diagnosis usually involves an imaging test of the brain, a 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.
(See also Overview of Brain and Spinal Cord Tumors in Children.)
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 9 years old, but they can occur in infants and throughout adolescence.
Starting from the top right label:
Astrocytoma (glioma)
Optic nerve glioma
Craniopharyngioma
Pituitary adenoma
Schwann cell tumor (nerve sheath tumor)
Ependymoma (glioma)
Brain stem glioma
Medulloblastoma
Pineal gland tumor
Meningioma
Oligodendroglioma (glioma)
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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 not known in most people. They sometimes occur in people with certain hereditary disorders (such as Gorlin syndrome or Turcot syndrome).
Symptoms of Medulloblastomas in Children
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 in Children
Magnetic resonance imaging (MRI)
Biopsy or often surgery to remove the entire tumor
Spinal tap
Doctors do an MRI scan of the brain to detect the tumor. Before the MRI scan is done, doctors inject a contrast agent into the child's vein (intravenously). Contrast agents are substances that make organs and other structures clearer to see on imaging tests.
Usually, instead of removing just part of the tumor for the sample, doctors surgically remove as much of the tumor as possible. In addition to examining the tumor tissue under a microscope, doctors also do genetic tests on the sample to help determine diagnosis, risk, treatment, and likely outcome.
To determine whether the tumor has spread, doctors do an MRI scan of the entire 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 scan of the brain to see whether the tumor has been completely removed. The results of these tests, the child's age, the results of genetic testing of the tumor, and the appearance of the tumor under a microscope together help doctors determine whether the tumor is standard (average) or high risk.
Treatment of Medulloblastomas in Children
Surgery, radiation therapy, and chemotherapy
(See also Cancer Treatment Principles.)
Medulloblastomas are best treated by surgically removing the tumor and by giving the child chemotherapy and radiation therapy.
Children under age 3 are not given radiation or are given radiation later on because at this age it can interfere with brain development, including later learning, thinking, reasoning, and understanding. In these children, a procedure called high-dose chemotherapy with stem cell rescue is sometimes performed. In this procedure, the child's stem cells are harvested, chemotherapy and other medications are given at high doses, and then the previously gathered stem cells are injected back into the child to help regenerate the cells killed by the chemotherapy.
Prognosis for Medulloblastomas in Children
How well children do after treatment generally depends on their age and on other factors that are specific to the tumor, such as genetic testing results, extent of surgery, and staging.
For children older than 3 years, the chances of surviving cancer-free for 5 years is about 80 to 85% if the tumor is average risk and about 60 to 70% if it is high risk.
For children 3 years old and younger, the outcome is harder to predict and depends on the results of the genetic testing done on the tumor. In about 40% of children in this age group, the tumor has already spread by the time they are diagnosed. In addition, radiation therapy is typically delayed or not done in this age group because of the side effects on the developing brain. 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.
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: How to Cope if Your Child Has Cancer
