Epilepsy

Reviewed by Dr Anthony Marson, lecturer in neurology, University of Liverpool

What is epilepsy?

Epilepsy is a condition in which people have epileptic attacks (also known as seizures). It is one of the more common neurological conditions, affecting 0.5-1 per cent of the population. Epilepsy is not a single condition, but a group of conditions with differing causes, treatments and prognoses.

Not all seizures are due to epilepsy. For example, drugs prescribed by doctors for other conditions - as well as substances such as alcohol - can sometimes cause seizures.

At present, most doctors would not diagnose a patient as epileptic if they had only suffered a single seizure. This is because epilepsy is defined as a condition in which patients have recurrent seizures.

The brain is made up of a vast number of nerve cells (neurones) which communicate with each other through electrical signals. The interplay between these neurones has to be carefully regulated for the brain to function properly.

Epileptic attacks happen when an abnormal electrical discharge occurs in the brain, disturbing its normal function. The type of seizure depends upon where this takes place, and how much of the brain is affected. During an attack, these discharges may cause:

twitching of the muscles

abnormal sensations (eg tingling on one side of the body or awareness of a strange taste or smell)

emotional symptoms such as fear or 'deja vu'

loss of consciousness.

Epileptic attacks are usually brief, lasting from seconds to a few minutes. Once the attack is over, the normal electrical activity of the brain resumes.

Epilepsy can start at any age, although it tends to first occur in children and the elderly.

What can cause epilepsy?

Epilepsy can be caused by a wide variety of conditions that affect the brain. In over half of those with epilepsy, no structural abnormality in the brain can be found. For a large proportion of these people the cause is probably genetic (see idiopathic generalised epilepsies). This is particularly the case when epilepsy starts in children and teenagers.

A structural cause is most likely to be found when epileptic attacks have a focal onset (meaning that they affect a particular area of the brain), which is why it is important to have a brain scan if a focal epilepsy is suspected.

Possible causes of epilepsy include:

abnormalities in the development of the brain (congenital abnormalities)

lack of oxygen during birth

infections (meningitis or encephalitis)

brain tumours

cerebral thrombosis or haemorrhage (stroke).

What are the prospects for people with epilepsy?

Fortunately, seizures will go into remission for 70-80 per cent of patients diagnosed as epileptic. However, the outcome of the condition is very much dependent upon the type of epilepsy and what causes it.

How does the doctor make a diagnosis?

Epilepsy is a clinical diagnosis. In other words, the diagnosis is not based upon the results of tests, but upon an accurate description of the attacks. As patients are often unconscious or unaware during seizures, it is extremely important for the doctor to get an eye-witness description of attacks from another person. The doctor will need to differentiate seizures from other conditions such as fainting fits or heart problems. Making a correct diagnosis can be difficult, and patients need to see a specialist with sufficient expertise, such as a neurologist. If a diagnosis of epilepsy is made, the following two tests are likely to take place:

An EEG (electroencephalogram): it is commonly believed that this is a diagnostic test for epilepsy. This is not true, as the EEG cannot tell us whether a patient has epilepsy. It can, however, help us to work out what type of epilepsy the patient has, which in turn will guide the choice of treatment and prognosis.

A CT scan or MRI scan may be carried out, especially if the patient is thought to have a focal epilepsy. These tests are used to look for brain abnormalities that may be causing the epilepsy.

You can suffer from epilepsy even if both the scan and the EEG are normal.

If there is any uncertainty about the diagnosis, it may be helpful to have a prolonged EEG. This sometimes takes place over a number of days using video recording equipment to record any attacks.

Treatment

Epilepsy is usually treated with medication prescribed by a specialist. In some cases, it can be treated surgically.

Epilepsy and pregnancy

The great majority of women with epilepsy go through pregnancy without difficulty. However, it is best to see your doctor before you get pregnant, particularly if you are taking tablets for your epilepsy.

What should you do if someone has a seizure?

If a person is having an epileptic seizure:

try to remove any objects on which the person could hurt themselves.

try to put the patient into the recovery position (lying on their side with their airway clear).

never put anything in the person's mouth during an attack.

stay with the person until they regain consciousness, then try to calm them.

if the fit lasts for more than 10 minutes an ambulance should be called immediately. Otherwise, it is usually not necessary to seek medical attention after a seizure.

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