Seizures, epilepsy and brain tumours

Up to 2 in 3 people diagnosed with a brain tumour will experience at least 1 seizure.

That may sound like a lot, but it's important to remember that not everybody who is affected by a brain tumour will experience seizures or epilepsy.

For those that do, the symptoms and severity will differ from person to person, so you may not have the same problems as someone with a similar diagnosis and treatment plan.

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.

Seizures are the most common first symptom leading to a brain tumour diagnosis in adults. However, you may only have seizures for a short period of time, for example, before treatment or due to swelling of the brain after surgery.

You're 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).

What is epilepsy?

Epilepsy is the tendency to have repeated seizures, so it's usually only diagnosed after you've 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.

What is likely to happen if I have a seizure?

The effects of a seizure depend on:

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

Types of seizures

When people think about seizures, they often think of convulsive seizures, where somebody loses consciousness, their body goes stiff and they fall to the floor with their limbs jerking. 

Convulsive seizures are rarely experienced by people living with a brain tumour and sometimes referred to as fits - but are more correctly called tonic-clonic seizures.

However, there are many different types of seizures.They can range from convulsive seizure to absent seizures, where someone just feels a bit strange or spaced out.

Your seizures may not exactly match one of the types described, but they will usually last the same length of time and follow the same pattern each time they happen.

Seizures are grouped according to:

Where the seizure starts (the onset)

Focal onset (previously called partial seizures)

• Start in and only affect one part of the brain

• The most common type of seizures associated with brain tumours.

Focal to bilateral

• Start as a focal seizure, then spread to both sides of the brain.

Generalised onset

• Start in and affect both sides of the brain at the same time
• Start without warning
• Rarely associated with brain tumours, but when they do occur they are usually a type known as tonic-clonic. 

Unknown onset

• The term for when it's not known where in the brain they started, for example, if the person is asleep or alone and the seizure wasn't witnessed.

Level of awareness during the seizure

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 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, so you may be confused or unaware of what you are doing
• you're 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

• involve a change in your movement, for example, you pluck at your clothes or your muscles go stiff before making jerking movements.

Non-motor seizures

• there is no change in your movement, but there may be sensory effects, for example changes to your vision, smell or hearing.

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, but you may experience something different:

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 you or a loved one is experiencing this, you should call 999 imediately.

What causes seizures and epilepsy?

Although epilepsy is more likely in certain low grade tumours, we don't fully understand why this is the case.

Suggestions include abnormally developed cells around the tumour that fire (send signals) more often, causing disorganised electrical activity in the brain, which leads to seizures. This is sometimes the cause in people with non-brain tumour-related epilepsy.

Or it could be due to the tumour causing a disturbance in the balance of chemicals in the brain, causing the nerve cells to fire more often.

It’s important to remember that an increase in the frequency of your seizures doesn’t necessarily mean that your tumour has returned or is regrowing.

Treating epilepsy

Treatment of seizures in people living with a brain tumour can be particularly complex and difficult due to the additional effects that having a brain tumour causes. Treatments include:

• anti-epileptic drugs
• neurosurgery
• complementary therapies.

Depending on your diagnosis, some seizure treatments may not suitable for you or you may have to try several treatments before you find the one that is best for you.

Treating epilepsy

Coping with seizures

One of the ways to cope with seizures is to identify any particular triggers for you and lessen your exposure to them. 

There are lots of strategies for making sure you're as safe as possible when you do have a seizure or you're better prepared to care for somebody who may experience seizures.

Coping with epilepsy

Frequently asked questions