What is epilepsy?

Epilepsy is actually a group of disorders characterised by chronic, recurrent, paroxysmal changes in neurological function caused by disturbances in electrical activity in the brain. Each episode is called a seizure. Epilepsy may occur as a result of brain injury or a lesion in the brain. It can also arise as part of many systemic illnesses. In some individuals, however, it arises spontaneously, with no predisposing brain injury or lesion and without any other medical illness. In these cases it is called idiopathic epilepsy.

There are cases of people having single, isolated seizures, which never re-occur. This is not called epilepsy.

Seizures may be divided, or classified, into different types, according to the International Classification of Epileptic Seizures. The underlying concept behind this classification is that some seizures (partial or focal) start in one area of the brain and either spread, or remain localised, while others are general over the whole brain from the beginning. Seizures may have motor (muscle movements), sensory (smell, taste), autonomic (sweating, salivation), or psychic (hallucinations) symptoms.

• Partial or focal seizures, which may be divided into simple partial seizures or complex partial seizures. In 'simple' partial seizures there is no alteration in consciousness or awareness of the environment, in 'complex' partial seizures there is. Simple or complex partial seizures can progress to generalised seizures with loss of consciousness and often convulsive motor activity.
• Primary generalised seizures.
  • These include the type of 'grand mal' seizure most people associate with epilepsy. These usually start without warning, although some people have a vague sense that something is about to happen. They start with a sudden loss of consciousness, a contraction of the muscles and a cry caused by forced expiration of the respiratory muscles. The person falls down and may remain rigid for some seconds. Soon after this there is rhythmic contraction of the limb muscles in all four limbs. The person may wet themselves and bite their tongue. The muscles relax, but the person remains unrousable for some time and once they come round may be drowsy, with a headache and will have no memory of the seizure. This so-called post-ictal state may last for days, but more commonly lasts for a few hours.
  • Absence seizures (petit mal) are another form of primary generalised seizures. Pure absence seizures are the sudden stopping of conscious activity without any convulsive muscular activity and the person does not fall down. They may be so short that they are not noticed. They may also be accompanied by minor motor activity such as fluttering of the eyelids, small chewing movements, or mild shaking of the hands. At the end of the seizure that person usually 'comes around' very quickly with no period of confusion. These usually begin in younger children (6 to 14) and rarely appear for the first time in adults. They can be the cause of learning difficulties in school as they may occur hundreds of times in a day and not be immediately recognised.
• Myoclonic seizures are sudden, short, single or repetitive muscle contractions involving one part of, or the entire body. If the whole body is involved the person falls suddenly, without losing consciousness. There is a juvenile form which begins in adolescence and has a genetic component.
• Atonic seizures are short losses of consciousness, where the person drops to the floor without apparent cause. They usually occur in children, frequently as part of another seizure pattern.
• Infantile, or 'salaam spasms' are primary generalised seizures which occur in infants between birth and 12 months. The child contracts the neck, upper body and both arms together, giving rise to the name 'salaam' spasms. There is usually an underlying neurological disease, but it can uncommonly occur in otherwise normal children.
• Status epilepticus is a situation in which there are repeated seizures with no periods of recovery between attacks. In the 'grand mal' type of seizure this can be life threatening. Absence status, on the other hand, can proceed for some time before it is recognised.

What causes epilepsy?

In infancy birth problems, such as a poor supply of oxygen or injury to the brain, infection, metabolic disturbances, genetic factors and congenital malformations are the usual causes.

Children can get seizures as a result of abnormally high fevers (not usually classified as epilepsy), infections, head injury and for no apparent reason.

In young adults head injury is one of the main causes of epilepsy, with the chances of developing recurrent seizures proportional to the extent of the injury. Other causes in this group tend to be associated with drug use, including alcohol withdrawal, or are idiopathic.

Between the ages of 30 to 50 brain tumours become a more common cause of seizures and may be present in 30% of patients with new focal seizures.

Above the age of 50 cerebrovascular disease, often causing strokes, is the commonest cause of focal or generalised seizures.

At any age, a variety of medical diseases can produce seizures through metabolic disturbance. For example, kidney or liver failure, too much or too little blood glucose, or disturbances of sodium balance.

How is epilepsy treated?

Drugs are currently the mainstay of treatment for epilepsy. The basic principle is to treat the patient with the lowest possible dose of a single agent which controls the seizures and allows normal functioning. It is important to know precisely which type of seizure is involved, so a good description from family members is vital. About 60 to 75% of people can achieve complete control of epilepsy this way. Poor control is often due to inappropriate drugs in the wrong dose. However, it is vital that the patient take their medication regularly, or even the right drugs in the correct dose will be ineffective.

There are a number of new drugs on the market for epilepsy, but I will cover the most commonly used in this country. Information on the newer drugs, and surgery for epilepsy, can be found in the links listed at the end of the article.

Partial seizures and 'grand mal' seizures are generally controlled with carbamazepine (Tegretol®), phenytoin (Epanutin®), phenobarbitone (Gardenal®) and sodium valproate (Epilim®). Typical absence seizures are controlled using ethosuximide (Zarontin®) or sodium valproate. Myoclonic an atonic seizures should be treated with clonazepam (Rivotril®) or sodium valproate, the latter preferred because it is less sedating.

Surgery is generally reserved for intractable epilepsy.

Where do we go from here?

In all cultures there is misunderstanding and superstition surrounding epilepsy which has led to discrimination against those with the disease in the workplace, at school and at home. There are even countries such as India and China where there are laws deterring people with epilepsy from marrying. Similar laws in some Western countries have only been repealed in the last few decades. In the developing world treatment is often inadequate or non-existant, leading to even greater misunderstanding of the disease among these populations.

A recent article in the British magazine New Scientist (New Scientist 27 September 1997) describes epilepsy as the 'hidden disease'. This summer (northern Hemisphere) the International League Against Epilepsy (ILAE), the worldwide professional organisation, the International Bureau for Epilepsy, the equivalent lay body, and the WHO launched a global campaign to improve the acceptance, treatment and prevention of epilepsy world-wide. Called 'Out of the Shadows' this includes an awareness programme to tell people that epilepsy is a treatable disorder. Many patients suffer more from public attitudes than from their seizures. Education is sorely needed to bring this disease out into the open.

Links

The South African National Epilepsy League (SANEL) has an excellent site, which offers information on treatment and support within this country.

The National Epilepsy Society of the UK is an excellent, informative site. It has a particularly good section on medication. The Columbian Presbyterian Medical Centre has plenty of information on surgical treatments for epilepsy. MedicineNet on epilepsy provides good general information, as does the Washington University comprehensive epilepsy program.