How epilepsy is diagnosed

How epilepsy is diagnosed

A person is usually diagnosed as having epilepsy if they have had two or more seizures that started in the brain. However, getting a diagnosis of epilepsy can be difficult because there is no single test that can diagnose epilepsy.

Diagnosing epilepsy involves doctors collecting information from different tests, talking to the person about what has been happening to them, and speaking to anyone else who might have seen the seizures. With all the collected information the most likely cause of the seizures may be found.

This page looks at how epilepsy is diagnosed.

What are epileptic seizures?

There are many underlying causes for seizures, but epileptic seizures happen because of interrupted brain signals. The brain has millions of nerve cells which control how we think, move and feel. The nerve cells do this by passing electrical signals to each other. If these signals are suddenly interrupted this can cause an epileptic seizure (sometimes called a ‘fit’ or ‘attack’). A seizure is a symptom that the way your brain is working is interrupted for a short time.

The brain has many different functions. Personality, mood, memory, movement, consciousness and our senses are all controlled by the brain. These can all be affected if a person has an epileptic seizure. Epileptic seizures can look different from person to person.

Anyone can have a single epileptic seizure at some point in their life. This is why a diagnosis of epilepsy is usually only considered when a person has had more than one seizure. However, if you have had only one suspected seizure your doctor may still want to investigate it, as there can be various possible causes.

How is epilepsy diagnosed?

If there is a possibility that you have epilepsy, your GP may refer you to a neurologist. A neurologist is a doctor who specialises in conditions affecting the brain and nervous system, such as epilepsy.

Much of the diagnosis of epilepsy is based on finding out what happened to you before, during and after the seizures.

What happened during the seizure?

Finding out what happened before, during and after a suspected seizure can often tell a lot about why it might have happened. For example, some types of faints can look like epileptic seizures. But often before fainting a person feels cold or clammy and their vision goes blurry. Whereas epileptic seizures often happen very suddenly and the person may have no warning that a seizure is about to happen.

How you felt afterwards can also help to explain what happened. For example, when someone comes round after an epileptic seizure, they may feel confused, very tired, and may want to sleep.

The person who had the seizure may not remember much, if anything, about it. This might be because they were unconscious at the time or very confused afterwards.

If you see someone having a seizure here are some questions that can help you give useful information about what happened.

• Where was the person and what were they doing before the seizure?
• Did you notice their mood change - were they excited, anxious or quiet?
• Were there any triggers for the seizure - did they feel tired, hungry, or unwell?
• Did they have any warning that the seizure was going to happen?
• Did they have any unusual sensations, such as an odd smell or taste?
• What made you notice the seizure – a noise, did they fall, or did their eyes roll?
• Did they appear to be ‘blank’ or stare into space?
• Did they lose consciousness or were they confused?
• Did they do anything unusual such as mumble, wander about or fiddle with their clothing?
• Did their colour change (become pale or flushed) and if so, where (face or lips)?
• Did their breathing change (e.g. become noisy or look difficult)?
• Did any part of their body move, jerk or twitch?
• Did they fall down, or go stiff or floppy?
• Did they wet themselves?
• Did they bite their tongue or cheek?
• How long did the seizure last?
• What were they like after the seizure - did they need to sleep?
• How long was it before they were able to carry on as normal?
• Did you notice anything else?

Looking at the medical history

Apart from the description of the seizure, there are other things that can help to explain why the seizure has happened. Your medical history and any other medical conditions will also be considered as part of the diagnosis.

Sometimes the cause of someone’s epilepsy can be found. For example, someone might develop epilepsy after they have had a head injury, a brain infection (such as meningitis) or a stroke. Or there may be a genetic cause (passed from parent to child) for their epilepsy - some inherited conditions, such as tuberous sclerosis, can cause epilepsy.

Finding out more about your medical history can sometimes help to find a reason why seizures have started.

For most people there are no clear reasons why they have epilepsy.

© Epilepsy Society
Information produced in March 2010