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A medulloblastoma is a type of primitive neuroectodermal tumour (PNET) that is found at the back of the brain, in the cerebellum. This part of the brain coordinates movement, balance, and posture and also participates in some of the functions of the cerebrum in ways that are not fully understood. Different types of medulloblastomas, such as desmoplastic, large cell, or anaplastic, may behave differently.

This is the most common cancerous brain tumour in children. It is usually diagnosed in children aged 4 to 8, and is more common in boys.

What causes a medulloblastoma?

We don’t know what causes a medulloblastoma. There is growing evidence that medulloblastoma is the result of a mistake that occurred in the early development of the brain’s cells.

There is no way to predict that a child will get a medulloblastoma and nobody is to blame if a child develops a tumour.

Researchers have been studying whether environmental factors, such as radiation, food, or chemicals, can cause brain cancer. At the moment, there is no definite proof that there is a connection.

Certain medical conditions are connected to a medulloblastoma. If a child has Turcot syndrome or Gorlin syndrome, there is a slightly greater chance of developing a medulloblastoma.

How many other children have medulloblastomas?

Medulloblastomas account for about 20 out of 100 brain tumours in children.

In Canada, about 40 to 50 children are diagnosed with a medulloblastoma each year.

What are some medical symptoms of a medulloblastoma?

Symptoms include headaches, vomiting, unsteadiness, double or blurry vision, and sleep difficulties. Children with this tumour may also have problems in school, because tasks like writing become more difficult. There may also be changes in their personality or behaviour. Sometimes these tumours block the flow of cerebrospinal fluid (CSF) through the pathways that drain CSF from the ventricles, or hollow channels, in the brain. This can lead to a condition called hydrocephalus.

The diagnosis of any brain tumour can be a long and difficult process.

If the symptoms are dramatic, the diagnosis may happen quickly. If they are milder, it can take months.

More information


Eric Bouffet, MD, FRCPC