Epilepsy Explained

WHAT IS EPILEPSY?

The brain is a highly complex structure composed of millions of nerve cells (neurones).  Their activity is usually well organised and they possess mechanisms for self-regulation. The neurones in the brain are responsible for a wide range of functions including consciousness and bodily posture. A sudden temporary interruption in some or all of these functions may be termed a “seizure” or “fit”.

Such an event may be caused by some disturbance arising within the brain itself (an intrinsic cause) or, more rarely, by an external factor such as temporary lack of oxygen or glucose. Many people have a single seizure at some time in their lives but this does not constitute epilepsy. If an individual has a tendency to experience repeated seizures due to an intrinsic disturbance of neuronal function within the brain, and then the term epilepsy may be properly used.

It should be noted, however, that epilepsy is not just one condition, and that it is not always easy to give an explanation in each individual case why seizures begin, or why they continue to occur. The epilepsies, therefore affect different people in differing ways. When offering explanations of epilepsy, it is important to remember that there are still many misconceptions about this condition.  People may need reassurance that it is not an illness or disease.

WHAT CAUSES EPILEPSY?

Any person’s brain has a capacity to produce a seizure if the circumstances are appropriate. Most brains are not likely to do this spontaneously and therefore can be said to have a high “seizure threshold” or high resistance to seizures. Individuals vary as to their threshold and it is probably one part of genetic characteristics. A person with a low threshold might develop epilepsy spontaneously without other factors being involved. Sometimes a predisposition to seizures can be seen in some families where several members are affected.

The genetics of epilepsy are not straightforward. In some individuals the existing seizure threshold may be lowered if the brain is subjected to unusual stimulation (such as a certain frequencies of flickering light and some drugs) or is injured. If the injury is severe, e.g. due to a road traffic accident, infection, birth trauma, stroke or tumour, then epilepsy may develop as a consequence.

Many individuals attribute the onset of seizures to some relatively minor event such as a blow to the head or an emotional upset. Although these cannot be completely discounted, in such cases it is likely that family predisposition to seizures plays a more important role.

HOW MANY PEOPLE HAVE EPILEPSY?

Epilepsy is the most common serious neurological condition affecting people of all ages. A prevalence rate of 0.5% (1 in 200) is usually quoted as a minimum prevalence for the U.K. This would mean that there are at least 350,000 people with epilepsy in this country.  Anyone can develop epilepsy; it occurs in all ages, races and social classes. Seizures tend to start in infancy or by late adolescence, but the incidence rises again after 65.

HOW IS A DIAGNOSIS OF EPILEPSY MADE?

Unlike most neurological disorders, there may be no physical signs that a person has epilepsy. The diagnosis is, therefore, made on the basis of a history of more than one epileptic seizure. An accurate eyewitness account is crucial to making a correct diagnosis, as the person experiencing the seizure usually has no recollection of what has happened.  A number of investigations may provide additional information although these tests do not make the diagnosis of epilepsy.

  • Blood tests – these check the general health of the person and help to exclude a metabolic cause for the attacks.
  • X-rays of the skull and chest – these help to exclude a structural cause for the seizures. Special studies (CT or MRI scans) of the brain itself may be requested by the physician if there is an indication that epilepsy has a structural cause. In most people such tests will be normal.
  • EEG (electroencephalogram) – this test measures the electrical activity of the surface of the brain. Electrodes are placed on the scalp and the signals picked up by the electrodes are then amplified and recorded. It is a painless procedure lasting about 40 minutes. It should be remembered that the EEG can only give information about the electrical activity of the brain during the period of recording. Only if patterns characteristic of epilepsy are seen during the routine recording is the EEG of value in the diagnosis of epilepsy. A negative EEG does not exclude a diagnosis of epilepsy. Sometimes ambulatory monitoring (longer term EEG) is used.

DIFFERENT TYPES OF EPILEPSY

Epilepsy may take many different forms and just knowing that a person “has epilepsy” gives very little useful information about that individual.  Epilepsy can broadly be divided into two categories, both producing a number of types of seizure.

Partial Epilepsy  

Epileptic activity starts in one small area of the brain.  The seizure may be simple or complex.

Simple partial seizures –  where the seizure mimics the normal function of the part of the brain which has been disturbed.  The seizure is usually brief.  Consciousness is not lost.  Possible symptoms are intense feelings of sudden fear or happiness.  Unpleasant smells, tastes or stomach sensations can occur.  These are often called and “aura”.  There may be symptoms affecting movement.  The head may be drawn to one side.  The hand or arm may become stiff and is drawn upwards.  There may be jerking movements in the limb affected.  Physical sensations may be experienced.  Perhaps a tingling or warmth down one side of the body.  Vision may be affected.  Flashing lights, balls of light or strange colours are typical symptoms affecting half of the vision.

Complex partial seizures – can develop from simple partial seizures or consciousness may be impaired from the outset affecting the person’s ability to function normally.  They can be brief and occasionally more prolonged.  Such seizures can result in complicated automatic behaviours or automatisms.  These include pulling at, putting on, or removing clothing; picking up objects; chewing, or lip smacking; and aimless wandering about or repeated movements.  Sometimes perceptions can change and things can appear bigger or smaller than they really are.  This can be very frightening and difficult to explain to others.  Perhaps even harder to accept are auras which relate to just feeling detached from one’s environment.  On recovery the person may be agitated and confused.  After the episode the person usually remembers nothing about what happened during the seizure.  The activity causing a simple or complex partial seizure may spread to other areas of the brain and may sometimes become a generalised seizure. 

Generalised Epilepsy

Epileptic discharges involve both hemispheres of the brain simultaneously and consciousness is lost.

Absences (also called Petit Mal) –  brief periods of interrupted or clouded consciousness, easily mistaken for daydreaming or inattentiveness.  They mainly affect children.  There is no warning.  The person will stop what they are doing and simply stare into space.  Slight flickering movements of the eyelids can sometimes be seen.  Eye blinking, eyeball rolling, face pulling or facial twitching can occur.  Seizures can be very frequent, sometimes occurring several hundred times a day.  Short intervals of loss of consciousness usually last only seconds, so muscle tension is not affected and the person does not collapse.

Tonic clonic seizures – the person will lose consciousness and fall to the ground without any warning.  The person may cry out but this does not mean they are in pain.  The contraction of the muscles forces air out of the lungs.  Breathing becomes very shallow so the person’s skin colour may go blue.  The arms and legs will go stiff which is the tonic phase.  Jerking movements of the arms and legs follows this and this is known as the tonic phase.  There is a build up of saliva in the mouth, which may look like foam, and because the person may have bitten their tongue it can appear pink in colour.  The person may be incontinent.  The seizure may last for several minutes and consciousness gradually returns without the need for intervention.  There may be a period of confusion afterwards and the person m ay experience a bad headache and need to rest.  Full recovery rarely takes longer than an hour but each person is different.

CAN EPILEPSY BE TREATED?

Yes, but the success depends on many factors: type of epilepsy, accuracy of diagnosis, accuracy of treatment, compliance, associated handicaps and social problems.

With appropriate drug treatment, seizures can be completely controlled in the majority of people. In some the tendency to have seizures diminishes with time but maximum control should still be sought as early as possible. It may be necessary to take anti-epileptic drugs for a period of years even if seizures have stopped.
Some people however continue to have seizures despite appropriate treatment. A small proportion of such people may benefit from neurosurgery but this is only usually recommended in people whose seizures can be shown to arise from activity in one discrete area of the brain. Even if seizures continue it should be possible to adjust the drug regime so that the condition remains stable, to allow the person to function at an optimum level.

Many people are able to keep their seizures to a minimum by avoiding situations that they know may bring on a seizure. These may include lack of sleep, too much alcohol, emotional upsets or not taking tablets as directed. Practising “self care” is a vital part of overall management of epilepsy.

IS EPILEPSY A DISABILITY?

If seizures can be completely controlled, and if the person can achieve a high level of confidence and self-esteem, then epilepsy should present no real obstacles to a full life. However, having seizures for the first time and being told that the diagnosis is “epilepsy” (about which there may be many misconceptions in the individual mind) can be very upsetting.

Careful counselling and health education can do much to alleviate anxiety for the individual and the family.

If the person continues to have seizures then there may be difficulties many aspects of daily living. But even in this situation, good psychological health can help minimise physical problems, which only occur from time to time. Individuals should be helped not to blame everything on their epilepsy, and there should be an emphasis on abilities rather than the extent of the disability.

Some people with epilepsy find it helpful to meet up with other people in their local area, who also have the same condition, for support and social contact. There are a number of local groups in Wales.

Merely labelling people as having epilepsy on the basis of a medical diagnosis of epilepsy ignores the rest of their attributes and characteristics both good and bad and should be avoided at all costs.

October 2002

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