How epilepsy is diagnosed

Diagnosing epilepsy is not simple. Doctors gather lots of different information to assess the causes of seizures. If you have had two or more seizures that started in the brain you may be diagnosed with epilepsy.

Epileptic seizures are caused by a disturbance in the electrical activity of the brain (and so they always start in the brain).

You may be diagnosed with epilepsy if you have:

• two or more seizures that happen more than 24 hours apart; or
• a single seizure, with a high risk of having further seizures.

Getting a diagnosis is not always easy because there is no single test that can diagnose epilepsy. Blood tests, an Electroencephalogram (EEG) and MRI scans are used to gather information for a diagnosis. Tests on their own cannot confirm or rule out epilepsy.

What is epilepsy?

Anyone can have a single seizure at some point in their life. This is not the same as having epilepsy, which is a tendency to have repeated seizures that start in the brain.     

What are epileptic seizures?

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 disrupted or too many signals are sent at once, this causes an epileptic seizure.

Mood, memory, movement, consciousness, and our senses are all controlled by the brain and can all be affected if someone has an epileptic seizure. Epileptic seizures can be different for each person.

The process of diagnosing epilepsy

The National Institute for Health and Care Excellence (NICE) produces guidelines for treating specific health conditions in England and Wales. If there is a possibility that you have epilepsy, NICE recommends that you are referred to a specialist (a doctor who is trained in diagnosing and treating epilepsy) and seen within two weeks. 

Your diagnosis is based on finding out what happened to you before, during, and after your seizures. For example, some types of faints can look like epileptic seizures, and often before fainting a person feels cold and clammy, and their vision goes blurry. But epileptic seizures happen very suddenly, and a person may have no warning that a seizure is about to happen.

If you have a seizure, you may not remember what has happened. It can be helpful to have a description of what happened from someone who saw your seizure, to pass on to your GP or specialist. 

Here are some questions that may help you, or someone who witnessed your seizure, to record information about what happened.

Before the seizure

• Did anything trigger (set off) the seizure, for example, did you feel tired, hungry, or unwell?
• Did you have any warning that the seizure was going to happen?
• Did your mood change, for example, were you excited, anxious or quiet?
• Did you make any sound, such as crying out or mumbling?
• Did you notice any unusual sensations, such as an odd smell or taste, or a rising feeling in your stomach? 
• Where were you, and what were you doing before the seizure?

During the seizure

• Did you appear to be ‘blank’ or stare into space?
• Did you lose consciousness or did you become confused?
• Did you do anything unusual, such as mumbling, wandering about, or fiddling with your clothing?
• Did your colour change (become pale or flushed) and if so, where (face or lips)?
• Did your breathing change (for example, become noisy or look difficult)?
• Did a part of your body move, jerk, or twitch? Did you fall down, or go stiff, or floppy?
• Did you wet yourself?
• Did you bite your tongue or cheek?

After the seizure

• How did you feel after the seizure – did you feel tired, worn out, or need to sleep?
• How long was it before you were able to carry on as normal?
• What else did you, or another person, notice ?

It may be helpful to record some information about your seizures to show the specialist when you see them.  

Looking at your medical history

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

Sometimes the cause of someone’s epilepsy can be found, for example, following a head injury, a brain infection (such as meningitis), or a stroke. Some inherited conditions (passed from parent to child), such as tuberous sclerosis, can cause epilepsy. 
However, for many people there are no clear reasons why they have epilepsy.

Treatment for epilepsy

Epilepsy is usually treated with anti-seizure medication (ASM). ASM aims to prevent seizures from happening but doesn’t cure epilepsy. Up to 70% (7 in 10) of people with epilepsy could have their seizures completely stopped with ASM. 

ASM does not stop seizures happening for everyone, so other types of treatment may be considered, such as vagus nerve stimulation (VNS) therapy or epilepsy surgery.

Reacting to a diagnosis

A diagnosis of epilepsy can affect people in different ways. Getting information about epilepsy and asking questions can be helpful for some people. We have information for people who are just-diagnosed.

Our confidential helpline provides emotional support and information for anyone wanting to know more about epilepsy. 
 

Epilepsy Society is grateful to Dr F J Rugg-Gunn, Consultant Neurologist & Honorary Associate Professor, Clinical Lead, Chalfont Centre for Epilepsy, who reviewed this information.

Information updated: February 2024