A seizure happens when a group of nerve cells in the brain discharge electrically in a chaotic and disorderly way. It can be caused by fever or by infections. Other causes may be lack of oxygen or glucose in the brain, the effects of poisons, a physical blow to the head or the effects of drugs, including alcohol.
But these seizures, reactions to known causes, are not epileptic seizures. Epilepsy would not be diagnosed till the person had two seizures for no apparent reason, unprovoked and spontaneous.
Sometimes a fainting spell (usually caused by insufficient oxygen supply to the brain) can mimic an epileptic fit even to the extent of involving jerking of the arms or legs. But in the case of fainting, such leg or arm movements last only for some seconds.
A person about to faint often feels light-headed as a result of low blood pressure. He or she will “come to” quickly and their brain will be back to normal within a couple of minutes. In a true epileptic seizure the person will be confused and drowsy for over five minutes, sometimes for several hours.
Up to 1 percent of people suffer from epilepsy and it is one of the most common disorders of the nervous system. Annual new cases are between 30 and 50 per 100 000 people in the general population.
Most epilepsy occurs in infancy or in early childhood. Adults have a low-level of epilepsy until about age 60 after which the risk of epilepsy steadily increases. Fortunately, in many of the new cases the risk of having a seizure disappears after a few years.
Sometimes a person may have had only a single convulsion for no apparent reason. Treatment is still advisable because of the potential for another attack in the future. The risk of this has been put as high as 80 percent. The possibility poses particular risks for anyone taking part in sports such as surfing, sailing or bike riding.
A study of epileptic seizures has shown that there are a large number of different types of seizures, each with its own particular characteristics. Some produce a loss of consciousness, others do not. One major difference discovered between seizures involves whether there is faulty electrical activity in only one part of the brain or in both brain hemispheres.
Each kind of seizure has its own distinctive brain wave pattern detectable by an Electroencephalography (EEG). One kind of seizure may involve jerking of muscles in a corner of the mouth; another may produce a peculiar sensation in one foot. Another may produce a sense of “déjà vu” or a “funny feeling” before producing a loss of awareness and confusion.
The so-called grand mal seizure involves the sudden convulsions in muscles with the resultant jerking of the limbs. Petit mal epilepsy, as it was formerly called, starts between the ages of three and eight.
Today it is called “childhood absence epilepsy” and in a typical absence-seizure, the child is “not with it”, staring into space for a few seconds before regaining full awareness and continuing with whatever it was doing before.
These seizures may be so fleeting that they are not noticed at all, or they may recur scores or even hundreds of times a day, interfering with normal concentration and learning.
Sometimes there is associated eyelid fluttering or nodding of the head. These seizures disappear during adolescence. Until then they can be treated with ethosuximide (Zarontin).
Careful diagnosis of which type of seizure is occurring enables the optimum treatment to be given and helps minimize any unwanted side effects. Typical side effects might be weight gain, sleepiness or a rash.
Juvenile myoclonic epilepsy (JME), which occurs between 10 and 18 years of age, involves sudden muscle spasms and jerks in the arms, particularly in the morning. Sudden collapses because the knees give way are also common.
Treatment with Epilim (sodium valproate) is very effective. Such seizures can be minimized by avoiding alcohol and by getting plenty of sleep. A person suspected of having epilepsy is normally given an EEG which in about half of all cases will detect some abnormality in the brain waves. The person can also be continuously video taped to detect signs of seizures.
A major advance has been the scanning of the brain using magnetic-resonance imaging. This gives a clear image of the brain and has simplified the detection of abnormalities or lesions that could possibly be removed by surgery.
Treatment with drugs can control most epilepsy. Treatment is based on having a regular meal pattern, medication, moderate alcohol consumption and adequate sleep. This enables nearly all sufferers to lead a normal active life. Of course certain activities which could pose danger in the case of a seizure, such as mountaineering or scuba diving, need to be avoided.