Epilepsy - what exactly is it?

All types of epilepsy have in common that in them epileptic seizures may occur from time to time without any recognisable cause. These seizures are caused by functional disturbances in the brain which appear suddenly and are temporary and short in duration. 5% of all people experience an epileptic seizure at some point in their lives. For the most part these people do not have epilepsy but they have what is called an "occasional seizure" which is triggered by a particular circumstance (e.g. fever during childhood years, poisoning, inflammation or alcohol). We talk of people having epilepsy only when they have had at least two epileptic seizures which were not triggered by a recognisable and immediately preceding cause. 1% of all people have epilepsy. The condition may arise at any age in a person's life, it is found equally frequently in all races and cultures and affects people from all levels of society.

Types of Seizures and Forms of Epilepsy

The epilepsies are a group of conditions which have varying symptoms. There is not a condition of epilepsy as such; but there are rather various epilepsy syndromes which differ from one another in significant ways. These therefore represent distinct clinical pictures which have particular types of epileptic seizures associated with them and they also each have other characteristic features. These characteristic features include, for example, particular changes in EEG (electroencephalogram or "brain activity") patterns, and different age groups at which the various types of seizure first appear or at which they may disappear of their own accord. To some extent we can think of an epilepsy syndrome as being a short-hand way of describing a particular form of manifestation of epilepsy.

What types of epileptic seizures are there?

In the human brain there are some 20,000,000,000 nerve cells which work together to control our thinking, movement, feeling and perception, e.g. of light and music. All of these functions of the brain may be impaired during an epileptic seizure, either individually or affecting various combinations of functions at the same time. During an epileptic seizure an outside observer may be able to observe only a characteristic type of physical movement (= "motor activity"). A disturbance in the sensory apparatus of consciousness may, in individual cases, be reported only by the person who is actually having the seizure. In the vast majority of cases epileptic seizures last for only a few seconds or minutes at most and will cease by themselves without any treatment being necessary. These are called "self-limiting" seizures. In some rare exceptions seizures may last for than 20 minutes. These are so-called "seizure states" which are also known by the terms "status epilepticus" or "continuous seizures."

Secondarily-generalised seizure

It is possible for a seizure to begin in a particular region of the brain but for it then to progress across the entire brain. This is known as a secondarily generalised seizure. In such cases the person may often remember the beginning of the seizure. When faced with a seizure, in order to help the doctors make the right decisions about the therapy which is required, it is far more important for people to be able to observe and report accurately the symptoms and the course of the seizure than it is to be able to make (overhasty) use of technical language about seizures.