Medulloblastoma

Medulloblastoma is a cancerous (malignant) brain tumor that begins in the lower back of the brain called the cerebellum. The cerebellum is concerned with muscle coordination, balance, and movement.

Medulloblastoma tends to spread to other areas around the brain and spinal cord through the cerebrospinal fluid (CSF), the fluid that surrounds and protects your brain and spinal cord. This tumor rarely spreads to other parts of the body.

Medulloblastoma is a type of embryonal tumor - a tumor that starts in fetal (embryonic) cells in the brain. Based on the different types of gene mutations, there are at least four subtypes of medulloblastoma. Although medulloblastoma is not inherited, syndromes such as Gorlin syndrome or Turcot syndrome can increase the risk of medulloblastoma.

Signs and symptoms of medulloblastoma may include headache, nausea, vomiting, fatigue, dizziness, double vision, poor coordination, unsteady gait, and other concerns. These symptoms may be related to the tumor itself or may be caused by pressure buildup in the brain.

Medulloblastoma can occur at any age, but is most common in young children. Although medulloblastoma is rare, it is the most common cancerous brain tumor in children.

Diagnosis

The diagnostic process usually begins with a medical history review and discussion of signs and symptoms. Tests and procedures used to diagnose medulloblastoma include:

Neurological examination. During this procedure, vision, hearing, balance, coordination and reflexes are tested. This helps determine which part of the brain may be affected by the tumor.

Imaging tests. Imaging tests can help determine the location and size of the brain tumor. These tests are also very important for determining the pressure or obstruction in the CSF pathways. A computed tomography (CT) scan or magnetic resonance imaging (MRI) may be done right away. These tests are often used to diagnose brain tumors. Advanced techniques such as perfusion MRI and magnetic resonance spectroscopy may also be used.

Tissue sample testing (biopsy). A biopsy is not usually done but may be recommended if imaging tests are not typical for medulloblastoma. Suspicious tissue sample is analyzed in a lab to determine cell types.

Removal of cerebrospinal fluid for testing (lumbar puncture). Also called a spinal tap, this procedure involves inserting a needle between two bones in the lower spine to draw cerebrospinal fluid from around the spinal cord. The fluid is tested to look for tumor cells or other abnormalities. This test is only done after managing pressure in the brain or removing the tumor.

Treatment

Medulloblastoma treatment usually includes surgery followed by radiation or chemotherapy, or both. Age and general health, tumor subtype and location, tumor grade and extent, and other factors play a role in treatment decisions. Options include:

Surgery to reduce fluid buildup in the brain. A medulloblastoma can grow to block the flow of cerebrospinal fluid, causing a buildup of fluid (hydrocephalus) that puts pressure on the brain. Surgery (external ventricular drainage or ventriculoperitoneal shunt) may be recommended to create a pathway for fluid to drain out of the brain. Sometimes this procedure can be combined with surgery to remove the tumor.

Surgery to remove the medulloblastoma. A pediatric or adult neurosurgeon (neurosurgeon) removes the tumor, taking care not to damage nearby tissue. Sometimes, however, it is not possible to completely remove the tumor because medulloblastoma forms deep in the brain near critical structures. All patients with medulloblastoma should receive additional treatments after surgery to target the remaining cells.

Radiation therapy. A pediatric or adult radiation oncologist administers radiation therapy to the brain and spinal cord, using high-energy rays such as X-rays or protons to kill cancer cells. Standard radiation therapy can be used, but proton beam therapy, available in a limited number of major health centers in the United States, delivers higher targeted doses of radiation to brain tumors, minimizing radiation exposure to nearby healthy tissue.

Chemotherapy. Chemotherapy uses drugs to kill tumor cells. Typically, children and adults with medulloblastoma receive these drugs as an injection into a vein (intravenous chemotherapy). Chemotherapy may be recommended after surgery or radiation therapy, or in some cases at the same time as radiation therapy. In some cases, high-dose chemotherapy followed by stem cell recovery (stem cell transplant using the patient's own stem cells) may be used.