Epilepsy - an introduction

Epilepsy is a neurological condition where there is a tendency to have seizures that start in the brain.

Not all seizures are due to epilepsy. Other conditions that can look like epilepsy include fainting, or when people with diabetes have low blood sugar and have a diabetic seizure. In this information when we use the term ‘seizure’ we mean epileptic seizure.

How seizures start

The brain has millions of nerve cells which control the way we think, move, and feel. The brain uses electrical signals to send messages from one nerve cell to another. 

If the messages are interrupted, or the electrical signals do not switch off when they are no longer needed, this can cause a brief change in the way the brain works. This interruption, or build up, of electrical signals can cause a seizure. 

Epilepsy is common

Anyone can develop epilepsy, at any time of life. It happens in people of all ages. There are over 600,000 people with epilepsy in the UK.

There are many different ‘epilepsies’

Epilepsy is not just one condition, but a group of many different ‘epilepsies’ with one thing in common: a tendency to have seizures which start in the brain. 

Just knowing that a person ‘has epilepsy’ does not tell you much about their epilepsy, or the type of seizures they have. However, in this information we use the term ‘epilepsy’ as it is a familiar term for many people. 

How epilepsy is described 

You may see epilepsy described in two ways. The type of epilepsy describes what has caused the seizures to start, and which part of the brain is affected during a seizure. For example, in the term ‘genetic generalised epilepsy’, ‘genetic’ refers to the likely cause (see below), and ‘generalised’ means that both sides of the brain are affected during a seizure. 

Another way to describe epilepsy is to talk about the type of seizures a person has. In this information we look at the types of epilepsy and not at the types of seizures. 

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: May 2024