Epilepsy is a condition that affects the brain. There are billions of nerve cells (neurons) in the brain, which are linked together to form chains. All of the functions of the brain are controlled by these neuron chains, and so movement, speech, thoughts, sensations and feelings all depend on the signals being passed in a regulated and orderly way. The activity of the neuron chains is coordinated by electrical and chemical signals.
People with epilepsy have recurrent bursts of abnormal electrical activity in the brain. This change in brain activity leads to an epileptic seizure. An epileptic seizure can take a number of different forms – it can cause changes in a person’s body movements, awareness, behaviour, emotions or senses (such as taste, smell, vision or hearing). Usually a seizure lasts for only a few seconds or minutes and then the brain activity returns to normal.
Having one seizure does not necessarily mean that someone has epilepsy – people can have a ‘one-off’ seizure.
‘Epilepsy’ is not a single condition: in the NICE guideline, the term ‘the epilepsies’ is used to show that not just one but many brain conditions can result in recurrent epileptic seizures. Some epilepsies start in childhood, some start in young people or in adults, while others start in older people; some last for only a short time and others last for a lifetime; some have little impact on a person’s life and others can have a major effect on a person’s ability to function and live their daily life.