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Medulloblastoma

Medulloblastoma is the most common central nervous system (CNS) embryonal tumour and the most common high grade childhood tumour, accounting for 15-20% of all childhood brain tumours. They are commonly found in children between ages of three and eight, with a higher occurrence in males.

Medulloblastomas usually develop in a part of the brain called the posterior fossa, and may sometimes spread to other parts of the brain or spinal cord, through the cerebrospinal fluid (CSF) that surrounds the brain. They are most commonly found in the cerebellum, an area of the posterior fossa that controls coordination and balance.

Due to the location of these tumours, they may block the flow of CSF leading to a condition called hydrocephalus, which raises the pressure inside the skull.

Types of medulloblastoma

In the past few years, our understanding of medulloblastoma has advanced significantly by studying their genetic make-up and increasing our molecular understanding of this tumour type. Researchers have been able to identify that medulloblastoma can be subgrouped in to four main groups that have been defined by demographic, clinical and genetic differences.

WNT medulloblastoma

This is the best known subgroup of all the medulloblastomas and has been identified in 10-15% of patients. The average age of occurrence is 10 years old and it is more commonly found in females. These tumours often occupy the fourth ventricle; the fluid filled space in the middle of the posterior fossa.

SHH medulloblastoma

This type of medulloblastoma frequently occurs in both infants (under three) and adults (over 16), but are less frequent in children aged three to sixteen. SHH medulloblastoma is commonly associated with a condition known as Gorlin syndrome, due to a gene mutation that causes the over-activation of cells, leading to the formation of a tumour.

Group 3 medulloblastoma

This type of medulloblastoma occurs more commonly in males than females, and are most common in young children ranging from one to ten years old. At diagnosis, these are often metastatic (already spread to other parts of the brain and spinal cord). Similar to the WNT medulloblastomas, the tumour is generally located within the fourth ventricle.

Group 4 medulloblastoma

This is the most common subgroup of medulloblastoma, making up around 35-40% of all cases. These tumours can occur in all ages but are most prevalent in mid-childhood.

Unfortunately, a full genetic test to determine the type of medulloblastoma that your child may have is not yet routinely available on the NHS, however hospitals are developing the techniques to be able to do this in the near future.

What are the symptoms of a medulloblastoma?

The signs and symptoms of a medulloblastoma are usually caused by increased pressure in the brain. Symptoms may include:

  • abrupt onset of headaches, especially in the morning
  • nausea and/or vomiting
  • feeling extremely tired
  • loss of balance and co-ordination which may lead to difficulty walking
  • abnormal eye movements
  • blurry vision caused by swelling of the optic disc at the back of the eye (papilloedema)

In some cases, the tumour can spread to the spinal cord, causing another set of symptoms, such as back pain, an inability to control the bowels and bladder and difficulty walking.

Questions you may want to ask your child's doctor:

  • What treatment options are available for my child?
  • Are there any genetic tests available for my child?
  • What might be the short and long term complications of treatment?
  • What services may be available to help my child and family cope?
  • When should I contact my child's medical team?
  • How can I contact my child's medical team?
  • Are there any clinical trials my child could take part in?

If you have further questions, need to clarify any of the information on this page, or want to find out more about research and clinical trials, please contact our team:

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About brain tumours

Jake helps children to understand a brain tumour diagnosis.

Dr Gajjar discusses embryonal tumours, including Medulloblastoma, PNET and ATRT and NPID, National Paediatric Information Day, 2016.