WHY DO SEIZURES OCCUR? WE DON’T REALLY KNOW WHY A SEIZURE OCCURSThe truth is that we don’t really know why a seizure occurs. We understand much about how the brain works and what a seizure is, how it happens, but not always why. We can explain how single cells fire, how they communicate with other cells, and a lot about the chemical and electrical makeup of neurons. We know that a cell’s function is affected by its chemical environment. We know, for example, that oxygen and glucose (sugar) are required to keep neurons healthy and working; with insufficient oxygen or glucose cells may fire abnormally and cause a seizure. Lack of blood supply to a part of the brain, such as after a stroke, can cause seizures by reducing the oxygen and chemicals necessary to keep these nerve cells functioning normally. Significant changes in important body chemicals such as calcium and magnesium can cause seizures; so can a lack of certain vitamins. These chemical changes may provoke a disturbance in the brain, or a single seizure, by influencing the threshold for firing, but they rarely cause epilepsy.A high fever, a blow to the head, or an infection of the brain such as meningitis or encephalitis, can provoke an isolated seizure by causing sufficient disruption of surrounding cells. But most seizures are the result of the interaction between the fiery speaker and the crowd, between the provocation to the brain and the surrounding neurons.*13\208\8*

• to stop the convulsion;

• to treat any underlying infection (e.g. urinary tract infection, otitis media) which might have caused fever;

• to prevent further febrile convulsions.

Febrile convulsions in most children stop of their own accord, usually after 4-5 minutes.

Short-lived febrile convulsions are not dangerous and do not cause brain damage. If a child convulses for more than 10 minutes then a doctor must be called immediately, or the child must be taken to the Accident and Emergency department of the nearest hospital. It is important to try and stop a convulsion, as there is a slight risk that prolonged febrile convulsions, lasting more than 30 minutes, may contribute to the later development of epilepsy (see p. 30). In order to stop a prolonged febrile convulsion, a doctor may give a medicine called diazepam (also called Valium or Stesolid), either by an injection into a vein or by a small tube inserted into the rectum, from which it is rapidly absorbed.

Some children who have had a first febrile convulsion will be admitted to hospital for observation and to find a cause of any underlying infection. Antibiotics may be given if an infection is found. A time in hospital may help to relieve parental anxiety. Interviews have revealed that the parents of at least half of the children who have their first febrile convulsion believe that their child is about to die, or has died. It is important to understand this concern and anxiety, to explain that this almost never happens, and reassure that children almost always make a full recovery following a febrile convulsion.

About one third of children will have a second or even third febrile convulsion. The risk of a child having a second or third febrile convulsion is greater if:

• the child is aged less than 12-15 months (and particularly if a girl);

• if the first febrile convulsion lasted more than 15-20 minutes or involved only one. side of the body (i.e. was a complex febrile convulsion);

• if the parents or brother or sister has had febrile convulsions, or has epilepsy.

There are some simple measures which can be taken to prevent further or recurrent febrile seizures. These measures include (whenever a child has an infection and is showing a rise in temperature):

• undressing the child;

• sponging him or her with tepid (lukewarm) water, and

• giving regular paracetamol (Calpol) (every 3-4 hours) which brings down the temperature. It is not a good idea to use aspirin for this purpose in very young children, as this drug may bring on further problems in the liver.

There are certain situations in which a parent might anticipate that a child’s temperature may well increase, and therefore that a febrile convulsion may occur. Such a situation might be after an immunization or vaccination (for example, the ‘triple’ vaccine, given three times in the first year of life, or the MMR (mumps, measles, rubella) vaccine given between 15 and 18 months of age). It is quite safe and sensible to give paracetamol at the time of vaccination and for 24-48 hours afterwards. With the MMR vaccine, there may be a very mild measles-like illness (with a high fever) 8-10 days after the vaccine has been given, and again, it would be wise to anticipate this and give paracetamol around that time.

In the past, anti-epileptic drugs were used to try and prevent further febrile convulsions from happening. It was shown that sodium valproate (Epilim) and phenytoin (Epanutin) were unsuccessful in preventing further febrile convulsions, and also did not alter the occurrence of convulsions without fever—that is, epileptic seizures. Although phenobarbitone has been shown to be effective in certain cases, this drug may cause significant side-effects in young children. In those few children who have repeated or long febrile convulsions, diazepam (Valium, Stesolid) may be given rectally, by parents after brief training. This medicine is used to prevent or stop the convulsion from lasting more than 30 minutes, but is only rarely necessary.

In a large prospective study of over 50 000 children carried out by the National Institute of Neurological and Communicative Disorders and Strokes in the USA, the incidence of febrile convulsions was 3.1 per cent, and the recurrence rate 32 per cent. By the time that the children had reached the age of seven years, more than one non-febrile seizure (that is, epilepsy) had developed in 0.5 per cent of those who had never had a febrile convulsion, and in four times as many—2 per cent—of those who had had a febrile convulsion. Children who had had prolonged or focal febrile convulsions, with evidence of pre-existing impaired development, were eight times more likely to develop epilepsy by the age of seven years than children with simple febrile convulsions, and 18 times more likely than children who had never had a febrile convulsion at all.

These figures show that one cannot deny the relation between some febrile convulsions (the complex and prolonged) and epilepsy. However, the parents of a child with one uncomplicated convulsion who has developed normally can be assured that the chances of subsequent epilepsy developing are very low—that the child has about 98 chances out of 100 of reaching the age of seven years without the occurrence of non-febrile seizures.

*89\188\2*