Medulloblastoma is the most common malignant brain tumor in children and adolescents. It grows very fast in the area of the cerebellum and often causes increased intracranial pressure with headache and nausea. The tumor can be operated on, irradiated and treated with chemotherapeutic agents. About half of those affected can be cured by this intensive therapy. Here you read all important information about the medulloblastoma.
Medulloblastoma is the most common malignant brain tumor in children and adolescents, accounting for 20%. In a city like Cologne with about one million inhabitants, about five children under the age of 15 get sick each year. Mostly the medulloblastoma is diagnosed between the fifth and eighth year of life. Boys are more often affected than girls. In adults, the tumor occurs much less often. Medulloblastoma accounts for only about one percent of all brain tumors.
Predominantly, the tumors develop in the posterior fossa. In children they are mostly in the middle, in adults rather laterally in the cerebellum. In many patients, the medulloblastoma grows into the cerebral waterways. This allows tumor cells to spread very easily over the brain water in the rest of the brain and also in the spinal canal. If these cells settle in a new place and form a daughter tumor there, one speaks of metastases. In every third affected person, the medulloblastoma was already scattered at the time of diagnosis. Most of the tumor is located in the central nervous system (brain and spinal cord). Very rarely they arise in a bone or in the bone marrow.
The medulloblastoma increases very rapidly and can grow into the surrounding tissue. Therefore, it is classified by the World Health Organization (WHO) as very malignant (grade IV). In addition, medulloblastomas are subdivided according to their tissue type:
- classical medulloblastoma
- desmoplastic medulloblastoma
- nodular (nodular) medulloblastoma
- Anaplastic medulloblastoma
- large-cell medulloblastoma
Therapy and prognosis may differ between these individual tumor types.
Since a medulloblastoma grows very fast, symptoms develop early. The tumor takes place in the head and often moves the brain waterways – that is, the brain water can not drain properly. It builds up, which increases the intracranial pressure, and it can cause a water head (hydrocephalus). Especially headache, morning sickness and vomiting as well as dizziness are typical signs of the pressure increase in the skull. In addition, sufferers can sometimes concentrate worse, feel tired and suffer from sleep disorders. Some develop vision problems.
The medulloblastoma displaces mostly cerebellar structures. As a result, patients often can not properly coordinate their movements and have walking difficulties. In principle, different muscle groups can be paralyzed.
Medulloblastoma: causes and risk factors
The medulloblastoma is formed by embryonic cells (ie very immature and undifferentiated cells) of the central nervous system. Why such cells suddenly begin to multiply uncontrollably is not yet clear. However, it could be observed that the tumor occurs more frequently in connection with certain chromosomal changes. As a risk factor for a medulloblastoma is ionizing radiation: Children who had to be irradiated because of another malignant disease ever before, therefore, have an increased risk of disease.
Medulloblastoma: examinations and diagnosis
Patients with brain tumor symptoms often visit their family doctor or pediatrician first. This inquires after the exact complaints and their course. If he finds evidence of a malignant tumor in the central nervous system, he usually remits the patient for further investigation to a specialized center for cancer (oncology). Doctors from different disciplines work together to make the right diagnosis. Again, a detailed survey of the medical history (anamnesis) and various examinations are necessary. The most important :
MRI and CT
Medulloblastoma is best visualized in magnetic resonance imaging (MRI). Most often, the patient is injected with a contrast agent into a vein before the examination. The tumor absorbs this contrast agent and illuminates irregularly bright in the MRI image. This allows you to determine its location, size and spread very well. Since a medulloblastoma can also spread into the spinal canal, in addition to the head and a recording of it is made.
If an MRI is not possible for certain reasons, or if a rapid diagnosis is necessary due to an emergency situation, the brain is visualized using computed tomography (CT).
Examination of the cerebrospinal fluid
The brain water examination (CSF diagnostics) complements a detailed diagnosis at the medulloblastoma. The doctor takes with a fine hollow needle some brain water, you mostly from the spinal canal (lumbar puncture). The sample is examined for tumor cells and for the presence of metastases in the spinal cord.
In addition, a tissue sample of the tumor is usually taken (biopsy) and examined under the microscope. This is necessary to be able to optimally design the subsequent therapy for the patient.
Due to its malignancy, medulloblastoma requires rapid and intensive treatment.
The treatment of choice for medulloblastoma is surgery. The surgeons try to remove as much as possible the entire tumor. Since the medulloblastoma mostly grows into the surrounding brain structures, this goal can almost never be achieved. That’s why more and more treatments follow after surgery.
Medulloblastoma: radiation and chemotherapy
If there are no tumor lesions (metastases), children are irradiated in the area of the head and spinal cord for three to five years after surgery and then treated with chemotherapeutic agents. This should also destroy individual tumor cells in the brain waterways.
If the medulloblastoma has already formed metastases, an individualized and intensified treatment plan will be developed.
If possible, children under the age of three to five should not be irradiated. You will receive chemotherapy directly after surgery. Usually, several drugs that kill the cancer cells are combined. Examples are chemotherapeutic agents such as vincristine, CCNU and cisplatin.
Sometimes the medulloblastoma transfers the brain waterways. If these can not be reopened by an operation, the brain water must be artificially derived. To do this, the surgeons place a small tube in the cerebrospinal fluid (liquor shunt). In addition, the brain water can drain either into an outer container or into the body. In 80 percent of cases, the liquor shunt does not have to be left permanently. As soon as the brain water drains off again by itself, it can be removed again.
Accompanying therapy measures
Accompanied by intracranial pressure symptoms can be treated with the cortisone preparation dexamethasone. Mostly it is used in the period of surgery and radiotherapy.
Depending on the symptoms, rehabilitation may be followed by acute hospital treatment. Psychosocial care for patients and their families is also offered in most hospitals.
Examination and treatment
For more information on examination and treatment, see the article Brain Tumor.
Medulloblastoma: disease course and prognosis
The course of the disease and the prognosis depend on different criteria for a medulloblastoma. It is favorable if the tumor can be removed completely surgically, there are no metastases and there are no tumor cells in the brain water. If individual tumor cells remain in the head after the operation, the tumor can grow again (recurrence). Relapses usually occur in the first three years, but in rare cases may still occur ten years after successful therapy. Therefore, all patients should have follow-up examinations years after successful therapy. With intensive therapy today more than half of the children can with one medulloblastoma to be healed.