by Dr Ben Fox

Created on: November 04, 2008

What is a seizure?

A seizure happens when some nerve cells in the brain misfire. A seizure has a range of effects including a brief moment of a dreamlike state, strange smells or taste, sudden changes in emotion and the shaking, twitching and loss of consciousness associated with a tonic-clonic seizure. Many people assume all seizures are tonic-clonic type but of course they are mistaken.

The brain is made up of millions of nerve cells, which are best imagined as a one legged jellyfish. Each leg' of the nerve has hundreds of little offshoots, which join to other nerves so they can talk' to each other. Very complex but organised talking' between the nerves controls all of our thoughts, feelings and actions.

Just before a seizure some of these nerve cells become overactive and the organised talking' breaks down. This leads to a seizure and the symptoms experienced depend on which part of the brain is affected.

One point to stress is having a seizure does not mean you have epilepsy. You have to have at least two seizures before the diagnosis of epilepsy is made.

Who has seizures?

Seizures can happen at any stage of life. For instance many young children have a febrile seizure when they are ill with a very high temperature. This is, of course, terrifying for the parents but has no long-term effects.

The elderly can develop seizures, which are often related to other medical problems such as arterial disease or dementia. If a pregnant woman develops eclampsia she has a high risk of seizures but once treated doesn't tend to develop epilepsy.

Types of seizure

There are 2 main types of seizures. They are focal seizures and generalised seizures.

1. Focal seizures as the name suggests occur in a specific part of the brain. They are the commonest type of seizure and give rise to symptoms such as sudden mood change, strange sights, sounds or smells or odd body twitches or chewing movements. It usually only lasts for a few seconds before stopping.

2. Generalised seizures are the typical shaking many people associate with epilepsy. The seizure affects both halves of the brain and therefore the whole body. Typically the twitching lasts from 10 seconds to 2mins and is followed by a brief period of unconsciousness. As the person comes round they will initially be vague and confused but soon are back to normal.

Causes of seizures

There are many different medical problems that cause seizures and epilepsy. For many people there is no obvious cause found and treatment is symptomatic only. Research

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