A disorder of brain function causing recurrent seizures
- Usually develops in children and young adults
- Some types run in families
- Gender and lifestyle are not significant factors
In a person who has epilepsy, recurrent seizures or brief episodes of altered consciousness are caused by abnormal electrical activity in the brain. Epilepsy is a common disorder, affecting about 1 in 130 people in the UK.
The condition usually develops in childhood but may gradually disappear. However, elderly people are also at risk of developing epilepsy because they are more likely to have conditions that can cause it, such as stroke.
Many people with epilepsy lead normal lives. However, people who have recurrent seizures may have to limit particular aspects of their lifestyle.
What are the causes?
In about a third of people with epilepsy, the underlying cause is not clear, although a genetic factor may be involved. In other cases, recurrent seizures may be the result of disease or damage to the brain, which may have various causes, including infections such as meningitis, a stroke, a brain tumour, a severe head injury, or prolonged febrile convulsions as a baby.
In people with epilepsy, seizures may be triggered by lack of sleep or by missing a meal. Other trigger factors include drinking excessive alcohol and visual effects such as flashing lights and flickering television and computer screens.
A single seizure is not labelled as epilepsy. For example, high fever in a child can result in a single febrile convulsion. People who abuse alcohol over a long period may have a seizure, either while drinking heavily or during withdrawal from alcohol (see Alcohol dependence). Very low blood glucose levels, which can occur as a result of treatment for diabetes mellitus, can also trigger a seizure, as can low blood calcium levels.
What are the types?
Epileptic seizures may be generalized or partial, depending on how much of the brain is affected by abnormal electrical activity. During a generalized seizure, all areas of the brain are affected at the same time, whereas during a partial seizure only one part of the brain is affected. Generalized seizures fall into two categories: tonic–clonic seizures and petit mal seizures. There are also two types of partial seizure: simple partial seizures and complex partial seizures. Both simple partial and complex partial seizures can become generalized tonic–clonic seizures.
This type of seizure may be preceded by a warning of an attack, known as an aura. This aura lasts for a few seconds and gives people an opportunity to sit or lie down before they lose consciousness and fall. Auras may consist of a sensation of fear, unease, or an unusual taste. During the first 30 seconds of a seizure, the body stiffens and breathing may become irregular or stop briefly. This stage is followed by several minutes of uncontrolled movement of the limbs and trunk. After the seizure, consciousness is regained, breathing returns to normal, and the muscles relax. Relaxation of the muscles in the bladder can cause incontinence. The person may be confused and disoriented for a few hours afterwards and may develop a headache. After a tonic–clonic seizure, the person affected usually has no memory of what has happened.
Status epilepticus is a serious condition in which a person has repeated tonic–clonic seizures without regaining consciousness in between. The condition can be life-threatening, and medical attention should be sought urgently.
Petit mal seizures
These seizures are sometimes known as absence seizures. They start in childhood and may continue into adolescence. Petit mal seizures are rare in adults. During an attack, the child loses touch with his or her surroundings and seems to be daydreaming because his or her eyes remain open and staring. Each attack lasts for between 5 and 30 seconds, and the child is usually unaware afterwards that anything was wrong. Since the seizures are almost never associated with abnormal movements or the child falling down, they may not be noticed. However, frequent attacks can affect schoolwork.
Simple partial seizures
During a simple partial seizure, the affected person remains conscious. The head and the eyes may turn to one side, the hand, arm, and one side of the face may twitch, or the person may feel a tingling sensation in some of these areas. Temporary weakness or paralysis of one side of the body may follow an attack. The person may also have strange sensations, such as odd smells, sounds, and tastes.
Complex partial seizures
Before this type of seizure, an affected person may experience odd tastes or smells or have a feeling of having already experienced what is happening (déjà vu). A brief dream-like state follows during which the person may be uncommunicative. During the attack, there may be smacking of the lips, grimacing and fidgeting. Afterwards, the person may not remember what has happened. Sometimes, a generalized seizure occurs as a progression of the complex partial seizure.
How is it diagnosed?
You should consult a doctor if you lose consciousness for an unknown reason or if someone witnesses you having a seizure. If your child has a seizure, you should also seek medical advice immediately. It is helpful if you can obtain full details of your seizure from a witness so that you are able to give the doctor a reliable account of what happened. The doctor may arrange tests to look for an underlying cause of the seizure, such as a brain tumour or an infection such as meningitis. If no cause is found or if you have recurrent seizures, you may have an EEG to look for abnormal electrical activity in the brain. An EEG also helps to diagnose the particular type of epilepsy because some forms produce a distinctive pattern of electrical activity. Your doctor may also arrange for CT scanning or MRI of the brain to look for structural abnormalities that may be causing epilepsy.
How might the doctor treat it?
If only one seizure has occurred, treatment may not be needed. However, an underlying problem, such as poor control of diabetes, may need to be treated. If you have had recurrent seizures, you will probably be treated with anticonvulsant drugs. Usually, the dose of the drugs is gradually increased until the seizures are controlled. Occasionally, a second anticonvulsant is needed.
You will probably have regular blood tests to monitor drug levels. If you have no seizures for 2–3 years, it may be possible to reduce the drug treatment or even stop it, depending on a number of factors including the results of the EEG tests and the brain scan. However, any changes in dosage must be carried out under medical supervision. Up to 4 in 5 people who stop taking anticonvulsant drugs have seizures again within 2 years. If drugs do not control the seizures and a small area of brain tissue is found to be their cause, it may be removed surgically.
People with status epilepticus need to be admitted to hospital immediately, where they will be given intravenous drugs to control the seizures.
What can I do?
If you have epilepsy, you should avoid anything that triggers an attack, such as stress or lack of sleep (see Living with epilepsy). You should carry identification that will alert others to your condition in case you have a seizure.
If you witness someone having an epileptic seizure, you can help by turning the person onto his or her side and protecting him or her from self-injury. If the seizure lasts for more than 5 minutes, you should call an ambulance and stay with the person until it arrives.
What is the prognosis?
About 1 in 3 people who have a single seizure will have another one within 2 years. The risk of recurrent seizures is highest in the first few weeks after an attack. However, the outlook for most people with epilepsy is good: with medication, more than 7 in 10 people go into long-term remission within 10 years.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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