Medulloblastoma is a fast-growing cancerous brain tumor that can spread through the cerebrospinal fluid (CSF) to other locations on the surface of the brain and to the spinal cord. It is the most common malignant brain tumor in children, accounting for about 20 percent of all pediatric brain tumors. Medulloblastoma is always located in the posterior fossa, the lower rear portion of the brain, and rarely spreads outside the brain and spinal cord.
Medulloblastomas are a type of cerebellar primitive neuroectodermal tumor (PNET) arising from cells that develop poorly at an early stage of a child’s life. Although the exact cause is unknown, researchers have identified genetic changes that may play a role in the development and growth of this type of tumor.
Most pediatric medulloblastomas develop in children younger than age 16, with more than 70 percent diagnosed in children under age 10. This type of tumor is slightly more common in boys than girls.
The signs and symptoms of medulloblastoma are usually caused by an increase in intracranial pressure due to blockage of the fourth ventricle. Although some children with medulloblastoma have no symptoms, the most common include:
These symptoms may also be caused by another medical condition.
If a brain tumor is suspected after a physical and neurological examination of your child, the doctor will schedule an MRI or a CT scan to view detailed images of the brain. If a tumor located in the posterior fossa of the brain is discovered, an MRI of the brain and total spine will be ordered to determine the anatomical features of the tumor and assess if it has spread beyond the site of origin. The next step will be surgical resection of the tumor.
Surgery to remove as much of the tumor as possible is the first line of treatment for medulloblastoma, followed by radiation and/or chemotherapy. Traditional surgical treatment requires a craniotomy in which a portion of the skull is removed to provide access to the brain. After removing the tumor, the neurosurgeon closes the opening with the patient’s own bone.
Radiation therapy uses high-energy x-rays to kill cancer cells or stop them from growing. If a portion of the tumor remains after surgery, the child is given higher-dose radiation therapy before chemotherapy. Proton therapy, which uses protons rather than x-rays, targets the tumor while avoiding healthy tissue, which is especially important in a developing child.
Chemotherapy involves the use of medications to kill cancer cells or stop them from growing. The medications are given through infusion or orally, and usually have side effects.
In some cases, the neurosurgeon will place a ventriculoperitoneal shunt to control increased intracranial pressure. The shunt is a plastic tube that moves the fluid creating pressure inside the brain to the abdomen, where the body absorbs it.
Using therapies currently available, the majority of children with average-risk medulloblastoma are cancer free five years from diagnosis.
The Children’s Neuroscience Center has a new brain tumor trial that is open to qualified participants. The research study is being conducted by David Sandberg, MD, Professor and Director of Pediatric Neurosurgery at McGovern Medical School at UTHealth and Children’s Memorial Hermann Hospital.
The study is called “Combination Intraventricular Chemotherapy Pilot Study: Methotrexate and Etoposide Infusions into the Fourth Ventricle or Resection Cavity in Children with Recurrent Posterior Fossa Brain Tumors.” It is open to patients who are age 1 to 21 years old with recurrent medulloblastoma (PNET), recurrent ependymoma, and recurrent atypical teratoid/rhabdoid tumors involving the brain and/or spine.
The study employs a novel means of treating malignant tumors that originate from the fourth ventricle: infusion of two chemotherapy agents directly into the fourth ventricle rather than systemic intravenous delivery. There will be no simultaneous systemic chemotherapy.
This study is listed at ClinicalTrials.gov, NCT # 02905110, under “Brain Tumor Recurrent.” If you would like additional information about this study, please contact Marcia Kerr, R.N. at firstname.lastname@example.org or by calling (713) 500-7363.
A phase I dose-escalation trial is now open to qualified participants at Children’s Memorial Hermann Hospital. The trial is the only study in the world investigating the direct administration of methotrexate into the fourth ventricle of the brain for the treatment of children with recurrent malignant fourth ventricular brain tumors.
The clinical trial is led by David Sandberg, M.D., FAANS, FACS, FAAP, director of pediatric neurosurgery at Children’s Memorial Hermann Hospital, the Memorial Hermann Mischer Neuroscience Institute at the Texas Medical Center, and the McGovern Medical School at UTHealth. Dr. Sandberg has pioneered the use of direct infusions into the fourth ventricle of the brain to treat children with recurrent malignant brain tumors in this location. A pilot clinical trial completed in August 2015 demonstrated that some patients with recurrent medulloblastoma experience a beneficial anti-tumor effect both within the fourth ventricle and at distant sites.
Delivering chemotherapeutic agents directly to the site of disease is particularly advantageous for children because it enables high drug concentrations at the site of disease origin while minimizing the side effects of chemotherapy by decreasing systemic drug exposure.
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