Seizures (epilepsy) and brain tumours

Up to 60% of brain tumour patients will experience at least one seizure. Seizures are the most common first (onset) symptom leading to a brain tumour diagnosis in adults.

You are more likely to have a seizure if:

you have a slow growing, low grade tumour
if your tumour is in one of the lobes of the cerebrum (cerebral cortex) or the meninges (the membranes that cover and protect the brain and spinal cord).

You are less likely to have seizures due to your brain tumour, if:

you have a high grade tumour
if your tumour is deep in the brain, in the brainstem or in the part of the brain known as the cerebellum.

If you have a high grade tumour and develop seizures, your tumour is likely to be smaller than high grade tumours not associated with seizures.

What is a seizure?

Our brains have billions of nerve cells which control the way we move, think and feel. They do this by passing electrical signals or messages to each other. So electrical activity is happening in our brains all the time.

A seizure happens when there's a burst of abnormal electrical activity that disturbs the way the brain normally works, mixing up the messages. This causes a variety of symptoms.

Types of seizures

When people hear the term seizure, they often think of convulsive seizures. This is where the person loses consciousness, their body goes stiff and they fall to the floor with their limbs jerking.

However, there are many different types of seizures.

They can range from feeling a bit strange or absent (spaced out), to the convulsive seizures sometimes referred to as fits, but more correctly called tonic-clonic seizures. Tonic-clonic seizures are rare in brain tumour patients.

What is epilepsy?

Epilepsy is the tendency to have repeated seizures, so it's usually only diagnosed after you have had more than one seizure. There are more than 40 types of epilepsy of which brain tumour-related epilepsy (BTRE) is one.

In brain tumour patients, seizures may be related to cells around the tumour that have developed abnormally. Or they may be due to an imbalance of chemicals in the brain caused by the tumour. Both of these can interfere with the normal electrical activity in the brain.

Am I likely to have seizures or brain tumour related epilepsy?

Up to 60% of brain tumour patients will experience at least one seizure. However, this may be only one, or you may only have them for a short period of time, e.g. due to swelling of the brain after surgery.

You are more likely to have a seizure or develop BTRE if you have a slow growing, low grade tumour, but this doesn't mean that you will have seizures. You're also more likely to develop epilepsy if your tumour is in one of the lobes of the cerebrum (cerebral cortex) or the meninges (the membranes that cover and protect the brain and spinal cord), rather than deep in the brain or in the brainstem or cerebellum.

You can develop epilepsy if you have a high grade tumour. In this case, your tumour is likely to be smaller than high grade tumours not associated with epilepsy.

What is likely to happen if I have a seizure?

This will depend on:

the type of seizure you have
where the tumour is in your brain.

Types of seizure

Seizures are grouped according to:

Where seizures start in the brain (the onset)

Focal onset (previously called partial seizures)

These start in and only affect one part of the brain
They're the most common type of seizures associated with brain tumours.

Focal to bilateral

These start as a focal seizure, then spread to both sides of the brain.

Generalised onset

These start in and affect both sides of the brain at the same time
They start without warning
They're rarely associated with brain tumours, but when they do occur they are usually a type known as tonic-clonic. (See the downloadable full fact sheet for more information).

Unknown onset

When it's not known where in the brain they started.
This can happen if the person is asleep or alone and the seizure wasn't witnessed.

Level of awareness (aware or impaired awareness)

Focal aware (previously called simple partial seizures)

Only a small part of one lobe of the brain is affected
You're fully aware, even if you can't speak
You'll remember the seizure afterwards, even if you can't describe it.

Focal impaired awareness (previously called complex partial seizures)

A larger part of one side of the brain is affected
Your consciousness is affected - you may be confused, unaware of what you are doing
You are unlikely to remember the seizure afterwards
You may feel tired afterwards.

Generalised seizures

Both sides of the brain are affected
Your awareness will affected in some way
Are rarely associated with brain tumours.

Whether your movement is affected

Motor seizures

involves a change in your movement,
e.g. plucking at your clothes, or your muscles going stiff before making jerking movements.

Non-motor seizures

there is no change in your movement, but there may be sensory changes, e.g. in your vision, smell or hearing.

Your seizures may not be exactly as one of the types described, but they will usually last the same time and follow the same pattern each time they happen. For some people, however, their seizures do not follow a pattern nor last the same time.

Location in the brain

The effects you're likely to experience will also depend on where the tumour is in your brain and what that area of the brain controls. If your tumour is located over two different areas of the brain, you may experience a combination of symptoms.

The following are examples of what can happen - you may experience something different:

Temporal lobe

Focal aware

an intense feeling of emotion

an unusual smell or taste

feeling of 'déjà vu' (I've been here or done this before)

'jamais vu' (familiar things seem new)

rising feeling in the stomach, like you may get on a fairground ride.

Focal impaired awareness

picking up or fiddling with objects or clothing
chewing or lip-smacking movements
uttering or saying repeated words that don't make sense
language problems, such as comprehension
wandering around in a confused manner.

These may start as a focal aware seizure and usually last 2–3 minutes.

Frontal lobe

Focal aware

Muscle stiffness or twitching that can spread from the hand or foot and may affect half of the body
feeling of not being able to speak despite being fully conscious.

Focal impaired awareness

making strange movements or postures, such as cycling or kicking, usually at night
screaming or crying out loudly or laughing uncontrollably.

These usually last 15–30 seconds.

Parietal lobe

Focal aware

numbness or tingling
burning sensation
feeling that an arm or leg is bigger or smaller than it is.

Focal impaired awareness

like the simple focal seizures in these lobes, these can affect your senses or vision.

These are less common than temporal or frontal lobe focal impaired awareness seizures and usually last 15–30 seconds.

Occipital lobe

Focal aware

visual disturbances, such as coloured or flashing lights
hallucinations (seeing something that isn't there).

Focal impaired awareness

like the focal aware seizures in this lobe, these can affect your
senses or vision.

These are less common than temporal or frontal lobe focal impaired awareness seizures and usually last 15–30 seconds.

Status epilepticus

Occasionally, seizures may not stop, or one seizure follows another without any recovery in between. If this goes on for 30 minutes or more it is called 'status epilepticus' or 'status'. This is uncommon, but potentially serious, and requires hospital treatment.

If a seizure continues for more than 5 minutes or repeated seizures occur without recovery in between, emergency (rescue) medication should be given and/or an ambulance should be called - do NOT wait.

An introduction to seizures (epilepsy) and brain tumours - PDF

Find out more about seizures (epilepsy) and brain tumours - including more information about what happens during different seizures - in the full fact sheet.

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