Epilepsy affects around 456,000 people in the UK. People with epilepsy have repeated seizures.
Around one person in every 20 in the UK will have a seizure (sometimes called a fit) in their lifetime, but this doesn't mean they have epilepsy. People with epilepsy have repeated seizures, not just one.
"A seizure is caused by a sudden burst of excess electrical activity in the brain," says Dr Chris Clough, consultant neurologist (brain specialist) at King's College Hospital, London. Not everybody having a seizure falls to the ground with their body twitching. Different parts of the brain control different sensations, functions and parts of the body, so the kind of seizure you have depends on the area of the brain where this electrical activity occurs.
There are around 40 types of seizure, ranging from a taste in the mouth to jerking limbs. Seizures are classified into two main groups: partial onset seizures, involving one area of the brain, and generalised seizures, involving the whole brain.
Some people with epilepsy have both partial onset and generalised seizures, and some have just one type.
Partial onset seizures (one area of the brain)
Two types of seizure involve one area of the brain:
- a simple partial seizure, when the person is aware of what is going on, and
- a complex partial seizure, when the person loses awareness and will have no memory of what happened.
Symptoms of a simple partial seizure can include:
- altered consciousness, such as a feeling of having been somewhere before (déjà vu),
- intense emotions, such as panic or joy,
- a change to the sensation of taste, smell, sight, sound or touch,
- muscles in the arms, legs or face becoming stiff, or
- twitching on one side of the body.
During a complex partial seizure, a person will appear in a kind of trance and may vomit, dribble or make strange noises or movements.
Partial seizures sometimes develop into generalised seizures.
Generalised seizures (the whole brain)
"These are usually the seizures that people think about when they imagine epilepsy. They involve falling to the ground and jerking all over," says Dr Clough.
There is more than one kind of generalised seizure, but individuals usually have the same symptoms each time. They can experience one or more of the following:
- Tonic seizure: muscles stiffen, which can make the person lose their balance and fall over.
- Atonic seizure: muscles relax, which can make the person fall down.
- Clonic seizure: muscles in the arms, legs or upper body twitch, and the person may lose consciousness. It lasts for up to two minutes.
- Myoclonic jerks: sudden, brief twitches in the arms, legs or upper body.
- Tonic-clonic seizure (what some people call an epileptic fit): the body becomes stiff, the person usually collapses and loses consciousness, arms and legs twitch and they may wet themselves.
- Absences: briefly losing awareness of surroundings, possibly several times a day. Absences mainly affect children but can occur in adults.
Some people with epilepsy will get a warning before a seizure, for example they will feel dizzy or experience a strange taste or smell. These are called auras.
Psychogenic (non-epileptic) seizures
Some people have seizures that look like epileptic seizures but aren't caused by abnormal electrical activity in the brain. "People have what we call non-epileptic seizures, which could be caused by psychological problems
," says Dr Clough. These are more likely to occur in people with anxiety or depressive illness.
These seizures are sometimes called dissociative seizures, pseudo-seizures or functional disorder. Anti-epileptic drugs don't help control non-epileptic seizures, but psychological therapies can help.