Medulloblastoma: Specialists and Information

The tumor develops from so-called embryonic, immature cells. It grows from the cerebellum into the surrounding tissue. This area includes, for example, the fourth ventricle, a brain chamber adjacent to the cerebellum. This ventricle is filled with cerebrospinal fluid, also known as CSF. The cerebrospinal fluid surrounds the entire brain and serves an important buffering function.

If the medulloblastoma invades the ventricle, it can release cancer cells into the cerebrospinal fluid and thus spread very quickly. This can lead to the formation of secondary tumors, known as metastases.

These primarily develop in areas that frequently come into contact with the cerebrospinal fluid, such as the meninges.

The causes of medulloblastoma are largely unknown. The embryonic, immature cells from which it develops have not yet differentiated. They begin to grow rapidly and uncontrollably.

There are some genetic changes known to be more frequently associated with medulloblastoma. These include, for example, changes in certain chromosomes of the embryonic cells. Children who have undergone radiation therapy for another illness are at increased risk. Radiation therapy, for example in connection with leukemia, can therefore be a risk factor.

A medulloblastoma causes symptoms very early on because it grows very rapidly. This leads to increased intracranial pressure, which triggers nonspecific symptoms. These symptoms could also be indicative of other diseases. Common symptoms include:

• headaches,
• Nausea,
• vomiting.

In addition, medulloblastoma causes various symptoms depending on where it has spread. Specific symptoms may include:

• Vision problems (such as strabismus),
• sensory disturbances (such as numbness),
• balance problems,
• coordination problems,
• signs of paralysis,
• changes in behavior.

In addition to a standard physical examination, imaging techniques are particularly important for detecting a medulloblastoma. These techniques provide an image of the brain and can thus reveal the size, location, and extent of the medulloblastoma.

Magnetic resonance imaging (MRI) is particularly helpful for this purpose. Using MRI, doctors can examine part or all of the patient’s body. An MRI can therefore also reveal whether the medulloblastoma has already metastasized.

The duration of the examination can vary from a few minutes to over an hour. For the examination, the patient is moved on a movable table into the machine, the tomograph. It resembles a large tube.

MRI uses magnetism and therefore does not require X-rays. Hydrogen atoms are the smallest particles in our bodies. They can be influenced by a strong magnet, such as during an MRI scan.

The concentration of hydrogen atoms varies depending on the tissue layer, which is why they can be easily distinguished from one another. Since the brain contains a particularly high number of hydrogen atoms, it can be imaged very clearly. Tumor tissue can also usually be easily distinguished from healthy tissue because it has a different hydrogen content.

Another important part of the examination is the lumbar puncture. In this procedure, a hollow needle is used to draw a sample of cerebrospinal fluid from the area around the spine. This sample is then examined in the laboratory for cancer cells, since cerebrospinal fluid often comes into contact with the tumor.

Because a medulloblastoma grows so rapidly, prompt and intensive treatment is necessary. Surgical removal is particularly important for treatment. Surgeons attempt to remove the entire tumor. However, this is not always possible, as the tumor may have already invaded the surrounding tissue.

In these cases, further treatment follows immediately after surgery. This can also be used to first shrink the tumor and then remove it completely.

The choice of follow-up therapy also depends on the age of the affected child.

Starting at around three to five years of age, children receive radiation therapy, also known as radiotherapy. This involves treating the affected area with ionizing radiation, such as X-rays or electron beams.

The radiation prevents the tumor cells from dividing, causing them to gradually die off. This also helps kill cancer cells in the cerebrospinal fluid and prevent further spread.

In young children, however, radiation therapy can lead to developmental disorders, for example, which is why it is not used in this age group.

Young children usually receive chemotherapy instead of radiation therapy. This involves the use of certain medications, known as cytostatic drugs. These contain active ingredients that inhibit further tumor growth.

However, the active ingredients in cytostatic drugs also attack healthy cells. As a result, side effects such as hair loss, nausea, and vomiting may occur during treatment.

Medulloblastoma can recur even after complete removal if individual cancer cells remain in the body. That is why good follow-up care and regular checkups are especially important to detect any new growth as early as possible.

In this case, the same treatment can be administered as was used when the tumor first appeared. Recurrences usually occur within the first three years after successful treatment.