Medulloblastoma

Medulloblastoma is a fast-growing, cancerous (malignant) brain tumor that starts in the cerebellum, the part of the brain controlling balance and coordination. It is the most common malignant brain tumor in children, though it can also occur in adults. This tumor can spread to other parts of the brain and spinal cord.

What is Medulloblastoma?

Medulloblastoma is a type of cancerous brain tumor that originates in the cerebellum, the lower back part of the brain responsible for movement, balance, and coordination. These tumors are considered high-grade, meaning they grow quickly and can spread to other areas of the brain and spinal cord through the cerebrospinal fluid (CSF).

Medulloblastoma is the most common malignant (cancerous) brain tumor found in children. While it primarily affects children, it can also be diagnosed in adults, though this is less common. The tumor forms from immature cells in the cerebellum, which is why it often affects balance and coordination. Because medulloblastoma grows rapidly, it can cause symptoms by increasing pressure inside the skull or by directly affecting the functions of the cerebellum. The tumor cells can also travel through the fluid that surrounds the brain and spinal cord, called cerebrospinal fluid (CSF), potentially forming new tumors in other areas of the central nervous system. There are different types of medulloblastoma, which are identified by their specific genetic features. Knowing the type helps doctors plan the most effective treatment. These types include WNT-activated, SHH-activated, Group 3, and Group 4, each with distinct characteristics and prognoses.

Symptoms

Symptoms of medulloblastoma often develop as the tumor grows and puts pressure on the brain or interferes with the cerebellum's function. Common signs include headaches, nausea, and vomiting, which are often worse in the morning. Other symptoms relate to problems with balance and coordination.

The symptoms of medulloblastoma can vary depending on the tumor's size and location, and whether it has spread. Many symptoms are caused by increased pressure inside the skull, a condition known as hydrocephalus, which occurs when the tumor blocks the normal flow of cerebrospinal fluid. Common symptoms include persistent headaches, especially those that are severe and worsen over time. Nausea and vomiting are also frequent, often occurring in the morning or waking a child from sleep. These symptoms may be mistaken for other common childhood illnesses. Other signs relate to the cerebellum's role in movement and balance. You might notice dizziness, clumsiness, or an unsteady gait (ataxia), where walking becomes difficult or wobbly. Changes in vision, such as double vision (diplopia), can also occur. In some cases, children may experience fatigue, irritability, or changes in personality.

Causes & risk factors

The exact cause of medulloblastoma is usually unknown, meaning most cases occur without a clear reason. However, a small number of medulloblastomas are linked to inherited genetic conditions or syndromes. These genetic changes are not typically passed down from parents in most cases.

Most medulloblastomas develop spontaneously, meaning they are not inherited and the specific cause is not identified. Scientists believe these tumors arise from random genetic mutations that occur during early development, leading to uncontrolled cell growth in the cerebellum. While rare, certain inherited genetic syndromes can increase a person's risk of developing medulloblastoma. These include Gorlin syndrome (also known as nevoid basal cell carcinoma syndrome) and Turcot syndrome. If a child has one of these syndromes, their risk of developing medulloblastoma is higher than in the general population. It is important to understand that having a risk factor does not mean a person will definitely develop medulloblastoma. Similarly, many people who develop the tumor do not have any known risk factors. Research continues to explore the genetic and environmental factors that might contribute to this disease.

How it's diagnosed

Diagnosing medulloblastoma typically begins with a physical and neurological exam to check reflexes, balance, and vision. Imaging tests like magnetic resonance imaging (MRI) of the brain and spine are crucial to locate the tumor and see if it has spread. A biopsy, where a small tissue sample is removed, confirms the diagnosis.

If a doctor suspects a brain tumor, they will usually order several tests. A neurological exam assesses your or your child's brain, spinal cord, and nerve function. This includes checking vision, hearing, balance, coordination, strength, and reflexes. These tests can reveal problems that suggest a tumor. Imaging tests are essential for diagnosis. Magnetic resonance imaging (MRI) of the brain and entire spine is the most common and detailed imaging test used. An MRI can show the tumor's size, exact location, and whether it has spread to other areas of the central nervous system. Sometimes, a computed tomography (CT) scan may also be used. To confirm the diagnosis of medulloblastoma, a neurosurgeon performs a biopsy. During this procedure, a small piece of the tumor is surgically removed. A pathologist then examines this tissue under a microscope to identify the type of tumor and its specific characteristics. This is the only way to definitively diagnose medulloblastoma. After diagnosis, a lumbar puncture (spinal tap) may be performed to collect cerebrospinal fluid (CSF). This fluid is then checked for tumor cells, which helps determine if the cancer has spread to the spinal fluid.

Treatment options

Treatment for medulloblastoma typically involves a combination of approaches, including surgery, radiation therapy, and chemotherapy. The specific plan depends on factors like the patient's age, the tumor's size and location, and whether it has spread. The goal is to remove as much of the tumor as possible and eliminate remaining cancer cells.

The first step in treating medulloblastoma is usually surgery. A neurosurgeon will attempt to remove as much of the tumor as safely possible without damaging healthy brain tissue. Removing most of the tumor can help reduce symptoms and improve the effectiveness of other treatments. After surgery, radiation therapy is often used to kill any remaining cancer cells. This treatment uses high-energy beams, like X-rays or protons, to target the tumor area and prevent recurrence. For very young children, doctors may delay or modify radiation therapy to minimize potential long-term side effects on brain development. Chemotherapy is also a key part of treatment. It involves using drugs to kill cancer cells throughout the body. Chemotherapy can be given orally (by mouth) or intravenously (through a vein). It is often used in combination with radiation therapy, especially for tumors that have spread or are considered high-risk. In some cases, targeted therapy or clinical trials may be considered. Targeted therapy drugs focus on specific vulnerabilities in cancer cells. Clinical trials offer access to new treatments that are still being studied, providing additional options for some patients.

Recovery & outlook

The outlook for medulloblastoma has significantly improved over time due to advances in treatment. Recovery and long-term outlook depend on several factors, including the patient's age, the tumor's specific type, how much of the tumor was removed during surgery, and whether the cancer has spread. Many children achieve long-term survival.

The prognosis for medulloblastoma varies greatly among individuals. Factors that generally lead to a better outlook include being older than 3 years at diagnosis, having a tumor that has not spread, and achieving a complete or near-complete removal of the tumor during surgery. Certain genetic types of medulloblastoma also have a more favorable prognosis. Despite successful treatment, medulloblastoma survivors, especially children, may experience long-term side effects. These can include problems with learning, memory, attention, and coordination, often due to radiation therapy or the tumor's location. Regular follow-up care with a team of specialists is crucial to manage these effects. Ongoing monitoring, including regular MRI scans, is necessary to check for any signs of the tumor returning. Support services, such as physical therapy, occupational therapy, and educational support, can help individuals manage any challenges they face during recovery and beyond. The goal is to help patients live the best possible quality of life after treatment.

When to see a doctor

You should see a doctor if you or your child experiences persistent or worsening symptoms that could indicate a neurological problem. These include severe or recurring headaches, unexplained nausea and vomiting, problems with balance or coordination, or changes in vision. Early detection is important for effective treatment.

It is important to seek medical attention promptly if you notice any concerning symptoms. While many of these symptoms can be caused by less serious conditions, it is always best to have them evaluated by a healthcare professional, especially if they are new, persistent, or getting worse. Specifically, look out for headaches that are unusually severe, occur frequently, or are accompanied by nausea and vomiting, particularly in the morning. Any new difficulties with walking, balance, or coordination, such as stumbling or clumsiness, warrant a doctor's visit. Other red-flag symptoms include double vision or other changes in eyesight, unexplained fatigue, or significant changes in behavior or personality. If you have any concerns about these types of symptoms, do not hesitate to contact a doctor for an evaluation.

Frequently asked questions

Is medulloblastoma always cancerous?

Yes, medulloblastoma is always a malignant (cancerous) tumor. This means it is fast-growing and has the potential to spread to other parts of the brain and spinal cord if not treated. It is considered a high-grade tumor.

Can adults get medulloblastoma?

While medulloblastoma is most common in children, it can also affect adults. However, it is much rarer in adults than in children. The symptoms, diagnosis, and treatment approaches are generally similar for both age groups.

What is the difference between medulloblastoma and other brain tumors?

Medulloblastoma specifically originates in the cerebellum, the back part of the brain controlling movement and balance. It is also characterized by its rapid growth and tendency to spread through cerebrospinal fluid, distinguishing it from many other types of brain tumors that may grow slower or in different brain regions.

What are the long-term effects of medulloblastoma treatment?

Long-term effects can vary but may include cognitive issues (problems with learning, memory, attention), hormonal imbalances, hearing loss, and difficulties with balance or coordination. These effects are often related to radiation therapy and the tumor's location. Regular follow-up care helps manage these challenges.

How common is medulloblastoma?

Medulloblastoma is the most common malignant brain tumor in children, accounting for about 10% to 20% of all childhood brain tumors. It is much less common in adults, making up a very small percentage of adult brain tumors.

Is medulloblastoma curable?

With modern treatments, many people with medulloblastoma, especially children, achieve long-term survival and can be cured. The chances of cure depend on factors like the tumor's type, whether it has spread, and how much was removed during surgery. Early diagnosis and aggressive treatment improve outcomes.

Sources

• MedlinePlus — Medulloblastoma
• Mayo Clinic — Medulloblastoma
• Cochrane Library — Medulloblastoma