Medulloblastoma Health Article

Definition

Medulloblastoma is a solid, cancerous tumor originating in the cerebellum of the brain. It is also known as a primitive neuroendocrine tumor.

Description

Medulloblastoma is the most common cancerous brain tumor of childhood. It accounts for 20% to 25% of all childhood tumors. Medulloblastomas can occur soon after birth and into puberty, but most tumors occur either before age ten or sometime in the late teens or early twenties. If these tumors are left untreated, they can spread to other areas of the brain and to the spine.

Medulloblastomas occur in the area of the brain known as the cerebellum. The cerebellum, located in the back of the brain above the neck, is the area of the brain responsible for controlling and integrating movement. A person could move their muscles without the aid of the cerebellum, but their movements would be clumsy and disorganized. Medulloblastoma tumors in the cerebellum can cause loss of functioning of the cerebellum, leading to this uncoordinated movement, called cerebellar ataxia.

If medulloblastomas are not detected early, they may spread cancer throughout the brain or spinal cord. If the cancer spreads to the spinal cord, a child may begin experiencing severe back pain, difficulty walking, and the inability to control their bladder and bowel functions.

Demographics

As stated earlier, medulloblastoma is a childhood cancer, occurring mainly in the first ten years of life. About half of all medulloblastomas occur in children aged five or younger. Boys tend to develop the tumors more than girls at a rate of approximately two to one. There are no current studies comparing the incidence of medulloblastoma between different racial and ethnic groups.

Causes and symptoms

Besides being male, there are no other known risk factors for medulloblastoma. This type of tumor can occur in association with two rare types of genetically linked family cancer syndromes, Gorlin's syndrome and Turcot's syndrome. Gorlin's syndrome is caused by a defect in a gene known as PTC located on chromosome 9. This defect can cause medulloblastoma as well as cancers of the skin and ovary. Turcot's syndrome is caused by a defective gene known as APC, and can present with cancer of the intestinal tract as well as medulloblastoma. It should again be stated that both of these syndromes are quite rare and only account for a fraction of medulloblastoma cases seen and reported.

Medulloblastoma can present in many ways. In infants, symptoms of the tumor can include an unusual increase in head size, vomiting, irritability, and lethargy. Since all infants generally have these symptoms at one time or another, it can be difficult for a parent or even a health care worker to recognize the initial presentation of medulloblastoma in babies and toddlers.

In older children and teenagers, medulloblastoma can present the same as in infants or much differently. Non-specific symptoms such as nausea and vomiting, headache, and vague visual disturbances can be the first sign of a tumor in the cerebellum. Other, more striking signs can be double vision, sudden difficulty writing, and problems walking and moving that worsen over time.

Diagnosis

The diagnosis of medulloblastoma is made with both clinical observation and imaging studies. If a parent has noticed some of the signs and symptoms listed above, then a visit to a pediatrician is certainly warranted. During the office visit, various specialized neurological tests will be done to see if there is any sign of a problem in the cerebellum or surrounding brain structures.

If there are indications of a tumor, then imaging studies can be done to see if a tumor can be detected. The two types of imaging studies done to detect medulloblastoma are magnetic resonance imaging (MRI) and computed tomography (CT) scan. The MRI uses a high-strength magnetic field to visualize the brain, and is very useful for detecting medulloblastomas. The CT scan uses x ray images reconstructed by computer. Like the MRI, a CT scan is also useful for detecting brain tumors as well as tumors that may have spread to the spine.

Treatment team

The treatment of medulloblastoma is optimally carried out in a medical center that has experience in treating this often difficult-to-treat cancer. Treatment and treatment planning is usually carried out by a multidisciplinary team of cancer specialists, including a pediatric oncologist (a doctor specializing in the treatment of childhood cancers), a pediatric neurosurgeon (a doctor specializing in childhood brain surgery), as well as a pediatric neurologist and radiation oncologist (a doctor specializing in the use of radiation to treat cancer).