• Medulloblastoma

    (Primitive Neuroectodermal Tumor)

    Definition

    Medulloblastoma is a type of brain cancer. It starts in an area known as the cerebellum, at the bottom and back of the brain.
    The cerebellum is the center for balance, coordination, and motor control. Over time, the tumor can cause problems with these functions. Because of the location, this tumor can also interrupt the flow of cerebrospinal fluid (CSF). This fluid surrounds and cushions the brain and spinal cord. Interrupted flow can cause a buildup of pressure in the brain.
    Cerebellum
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    Causes

    Cancer occurs when cells in the body divide without control or order. Cancer cells may start to divide out of control because of a defect in the DNA or instruction for the cells. The defect may be inherited or may randomly occur during normal cell changes.
    Eventually these uncontrolled cells form a growth or tumor. These growths can invade nearby tissues or move into the CSF. This can spread cancer throughout the brain or spinal cord.

    Risk Factors

    Medulloblastoma occurs at any age, but is more common in children. It is also more common in males.

    Symptoms

    At first, symptoms may not be noticeable or may not occur all the time. Over time, these symptoms can worsen.
    Possible symptoms include:
    • Nausea and/or vomiting
    • Headaches, especially in the morning
    • Lack of coordination in the upper part of the body
    • Vision problems, such as double vision or inability to look up with the eyes
    • Changes in appetite
    • Changes in behavior
    • Stumbling
    • Falling
    • Lethargy
    • Seizures

    Diagnosis

    The doctor will ask about symptoms and medical history. A physical exam will be done. Tests may include:
      Imaging tests of the brain and surrounding structures may be needed to identify or locate the tumor. Images may be taken with:
    • Biopsy—A tissue sample from the tumor is taken to identify the type of cancer.
    A lumbar puncture may be done to look for cancer cells in the CSF. A bone marrow biopsy may also be done. These tests can help determine if the cancer has spread.
    The physical exam combined with all of the test results, will help to determine the stage of cancer. Staging is used to guide a treatment plan. Like other cancers, medulloblastoma is staged from I-IV. Stage I is a very localized cancer, while stage IV indicates a spread to other parts of the body.

    Treatment

    Treatment depends on age, overall health, and the stage of the cancer. For example, radiation may be used before surgery to shrink the tumor or after to make sure all the cancer has been removed.
    Main goals of treatment include:
      Initial removal of as much of the tumor as possible
      • To relieve symptoms caused by pressure on nearby structures
      • To allow better flow of CSF
    • Additional treatment to eliminate the cancer and prevent it from coming back.

    Surgery

    A craniotomy uses a small hole in the skull to remove part or the entire tumor.
    If there is a problem with the flow of CSF, one of the following may also need to be done:
    • Temporary or permanent ventriculoperitoneal (VP) shunt—Plastic tubing allows CSF fluid that has built up in the brain to flow out to the abdomen or chest.
    • Endoscopic third ventriculostomy—A small hole is made below the brain that allows normal flow of CSF.
    • External ventricular drain (EVD)—A plastic tube runs from the brain to a bag outside of the body. This allows excess CSF to flow out.

    Radiation Therapy

    Radiation therapy is the use of radiation to kill cancer cells and shrink tumors. It may be used before surgery to reduce the size of the tumor or to reduce symptoms if surgery is not appropriate. The dose and delivery of radiation will be measured to reach the maximum benefit with minimum side effects.
    If the tumor has spread along the CSF pathway, craniospinal radiation may be done. This is a special type of radiation on the entire brain and spinal cord.

    Chemotherapy

    Chemotherapy is the use of drugs to interfere with the growth of cancer cells. It may be given in many forms including pill, injection, or IV depending on individual needs. The drugs enter the bloodstream and travel through the body killing mostly cancer cells. Some healthy cells are killed as well, which leads to side effects.
    Chemotherapy may be used to support other treatments.

    Medications

    Targeted therapy uses medications to interfere with the growth of the cancer cells. For example, medications can block the growth of new blood vessels needed for cell growth or block chemical signals needed for cancer growth and function.

    Prevention

    There are no current guidelines to prevent medulloblastoma because the exact cause is unknown.

    RESOURCES

    American Brain Tumor Association http://www.abta.org

    American Cancer Society http://www.cancer.org

    CANADIAN RESOURCES

    Brain Tumor Foundation of Canada http://www.braintumour.ca

    Canadian Cancer Society http://www.cancer.ca

    References

    Brain and nervous system cancers. Nemours Kids Health website. Available at: http://kidshealth.org/en/parents/brain-tumors.html. Updated March 2013. Accessed January 7, 2015.

    Brain and spinal cord tumors in children. American Cancer Society website. Available at: http://www.cancer.org/acs/groups/cid/documents/webcontent/003089-pdf.pdf. Accessed January 7, 2015.

    Medulloblastoma in children. Boston Children’s Hospital website. Available at: http://www.childrenshospital.org/health-topics/conditions/m/medulloblastoma/overview. Accessed January 7, 2015.

    Revision Information

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