Classification of Seizure Types

Generalised Seizures (seizures that affect the whole brain)

Absence Seizures
Absence seizures mostly affect children of primary school age and consist of brief (up to 30 seconds) periods of loss of awareness which may happen many times a day. The child appears to stare vacantly, the eyes may flutter or turn upwards. The child is unaware of his/her surroundings, but recovery is prompt. Absence seizures are often mistaken for daydreaming or lack of concentration and can disrupt learning by creating gaps in information received.

Tonic–clonic Seizures
Tonic–clonic seizures are recognised by a sudden loss of consciousness, the body stiffens (tonic phase) quickly followed by general muscle jerking (clonic phase). Breathing may appear difficult and the person may bite the tongue. The seizure ends when the jerking stops, muscles relax and normal breathing returns. Tonic–clonic seizures usually last 1–3 minutes, seldom longer. There may be a period of confusion after the seizure and the person may want to sleep.

Myoclonic Seizures*
Myoclonic seizures are uncontrolled muscle jerks. These seizures usually occur soon after waking or before going to bed when the person is tired. As a generalised seizure a loss of consciousness occurs but it is very brief and hardly noticeable.

Tonic Seizures*
Tonic seizures are generalized seizures causing the muscles to stiffen and if the person is standing they will fall quite heavily to the floor. This type of seizure often causes head injury and it is advisable for the person to wear a protective helmet to avoid constant injury.

Atonic Seizures*
This form of seizure activity can be characterised by a sudden and very brief loss of ability to stand or sit upright. Usually the person nods his head, slumps forward, or actually falls to the floor motionless. After the seizure the person may seem a little disorientated for a few seconds. They can be called “drop attacks”.

Partial Seizures (seizures that occur in just one part of the brain)

Simple Partial Seizures*
The symptoms the person experiences will depend on the function that part of the brain controls. The person remains fully conscious throughout the seizure.

This type of seizure may begin with a stiffening or twitching of an arm or leg or the person may lose the ability to speak. This type of seizure usually lasts for less than a minute and then the person recovers.

Complex Partial Seizures
Complex partial seizures vary widely. Often there is a loss or distorted awareness of surroundings. Inappropriate actions such as chewing movements and fiddling with clothing or aimless wandering may occur. After the seizure there may be a short period of confusion.

Note: It is not unusual for people to have more than one type of seizure.

*Reprinted from Epifile with the permission of Epilepsy Australia
August 2002

This information provided by the Epilepsy Association of South Australia and Northern Territory Inc on the Internet is designed to provide basic information about epilepsy. It is not intended, nor does it constitute medical or other professional advice. Diagnosis and advice on medical care or other assessments should be sought from a medical practitioner or suitably qualified professional.