Posterior fossa tumour: types, symptoms, treatment

Inside the skull, a sheet of tissue separates the upper brain from a smaller space at the back and bottom. This lower space is the posterior fossa. It holds the cerebellum, which coordinates balance and movement, and the brainstem, which carries messages between the brain and body and controls vital functions such as breathing.

Posterior fossa tumour is therefore a description of location rather than one diagnosis. Cancer Research UK lists medulloblastoma, which develops in the cerebellum, and posterior fossa ependymoma, which arises from cells lining the fluid spaces, among the tumours found here. Other growths at the back of the brain include slower-growing tumours and, in adults, tumours that have spread from elsewhere.

Posterior fossa tumours are particularly associated with childhood. Cancer Research UK says medulloblastoma can affect children of any age but is most common between 5 and 9, and is more common in boys than girls. Adults can get it too, although this is rare.

The NHS notes that brain tumours overall can affect people of any age but become more common in older adults, and that some types are more common in children. For most childhood tumours the cause is unknown. Cancer Research UK says fewer than 5 in 100 medulloblastomas are linked with inherited syndromes such as familial adenomatous polyposis or Gorlin syndrome, and that most families should not blame themselves or anything they did.

Pressure builds when a tumour in this tight space blocks the normal circulation of cerebrospinal fluid. Symptoms may develop over a few weeks or months and are often general, so they are easily mistaken for less serious illness.

• Headaches that are worse in the morning, often easing after being sick.

• Feeling or being sick, sometimes persistently.

• Double vision or other changes in eyesight.

• Unsteadiness: a child may find it hard to sit or stand unsupported and may fall backwards.

• Irritability, poor appetite, tiredness or changes in behaviour.

• In babies, a head that is growing quickly or a swollen soft spot (fontanelle), sometimes found at a routine check.

• In adults with ependymoma, dizziness is also listed by Cancer Research UK.

The NHS advises seeing a GP if headaches are different from usual or are getting worse, or if symptoms such as seizures, vision problems or behavioural change appear. If the GP cannot find a more likely cause, they can refer on for specialist assessment, often with a brain scan. Where scans show a mass, the case goes to a specialist brain tumour team.

Cancer Research UK lists a CT scan and an MRI scan as the first tests for medulloblastoma, with a lumbar puncture sometimes used to look for tumour cells in the fluid around the brain and spine. Younger children may need sedation or a general anaesthetic to lie still. The exact type cannot usually be named until a sample of the tumour has been examined, so families often wait a short time for that answer.

Modern pathology also looks inside the tumour cells for genetic and molecular features. These help doctors judge how the tumour is likely to behave and which treatments may work best.

Surgery is usually the first treatment, with the aim of removing as much tumour as can be done safely and taking a sample for diagnosis. In children it is carried out by a paediatric neurosurgeon. Rarely, chemotherapy comes first to shrink the tumour.

If fluid has built up (hydrocephalus), symptoms can include headache, sickness, seizures, eye problems, and problems with strength, balance or coordination. Cancer Research UK says this is treated with an operation, either making a hole to drain fluid within the brain (a ventriculostomy) or placing a tube called a shunt that drains it to another part of the body, usually the tummy. The surgeon may do this at the same time as removing the tumour.

Steroid tablets are often prescribed to reduce swelling around a brain tumour while plans are made, and anti-epileptic medicines may be added if there have been seizures.

Posterior fossa syndrome is a group of symptoms that can follow surgery to the back of the brain. Cancer Research UK says around 25 to 30 out of 100 children are affected, usually from one day to a week after the operation.

It may include difficulty speaking (from slowed or slurred speech to not speaking at all), difficulty swallowing, poor muscle tone and balance, jerky movements, weakness on one side and mood or behaviour changes that seem out of character. It can be mild or severe, and there is no way to predict who will be affected.

Symptoms usually improve slowly over weeks or months, although for some children they may not go away completely. Speech and language therapists, physiotherapists and occupational therapists are usually involved in rehabilitation, and research is continuing into what causes the syndrome.

Further treatment depends on the tumour type, whether it has spread, how much was removed and the person's age. After surgery children usually have another MRI and often a lumbar puncture. For medulloblastoma, Cancer Research UK explains that children are then placed in a standard-risk or high-risk group, and children under 3 are always in the high-risk group.

In very young children specialists generally try to avoid radiotherapy to the whole brain and spine because the risk of long-term side effects is higher, and may use chemotherapy to keep the tumour under control instead. Older children usually have chemotherapy and radiotherapy.

For ependymoma, Cancer Research UK says surgery is the main treatment, with radiotherapy and less commonly chemotherapy, and that follow-up may include an MRI scan every 3 to 6 months for two years. Long-term review, including hearing, hormones, learning and growth, is part of care for many survivors, so a specialist team will explain what to expect for the specific tumour.

Call 999 for a seizure that does not stop, a sudden severe headache with drowsiness or vomiting, collapse, or new weakness or speech difficulty. Take a child to A&E or call NHS 111 urgently if they become very sleepy, cannot be woken easily, or vomit repeatedly with a severe headache.

In the UK, children with suspected or confirmed brain tumours are looked after in specialist children's cancer centres with neurosurgery, oncology, nursing, play, psychology and education support. Adults are managed by neuro-oncology multidisciplinary teams. Anyone seeking a private opinion can ask for the pathology and scan reports to be shared with the NHS team so that treatment plans stay coordinated.

Hearing that a child needs brain surgery can feel overwhelming. Specialist nurses and the cancer information nurse lines run by charities can explain terms and next steps in plain language.