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This article was published in July 2017. The information may be out of date. Please check our epilepsy information or our site A-Z.

ILAE new seizure classification - why rename seizures and what it all means

18 Jul 2017

The International League Against Epilepsy (ILAE) has announced some new names for seizures and some new seizure types. Epilepsy Action advice and information services officer Grace Haydon explains what the changes are and the reasons behind them


The ILAE is a worldwide group of epilepsy professionals, which aims to increase knowledge about epilepsy and improve epilepsy treatment and care. In 1981, the ILAE created a classification system for seizure types: a way of naming seizures and putting them into groups. This classification is still widely used by healthcare professionals all over the world. The ILAE has now updated the 1981 classification with new names and categories, with the aim of making the way doctors describe seizures more accurate. We explain what the changes are, and what they might mean for you.

Why change the names?

Seizure classification means healthcare professionals have a clear set of guidelines telling them what different seizures look like, and what to call them. It’s important that healthcare professionals all understand and use the same names to describe seizures, to avoid confusion. Being able to accurately decide what type of seizure someone has is also important, because some medicines and treatments can help some seizure types but not others.

The ILAE has updated the classification to better reflect the latest knowledge about seizure types. They also want to make sure that the names for seizures are easy for both healthcare professionals and people with epilepsy to understand.

What is different?

These are the main changes from the old seizure classification to the new. 

In the old classification, seizures that start in one side of the brain were called partial seizures. These are now called focal seizures.

The new classification splits focal seizures into two groups according to what level of awareness you have during one. If you remain alert and aware of your surroundings throughout, it’s called a focal aware seizure. This replaces the old term simple partial seizure. If your awareness is affected at any time during a focal seizure it’s called a focal impaired awareness seizure. This replaces the old term complex partial seizure.

The new classification has introduced a new type of seizure called a focal to bilateral tonic-clonic seizure. This is a tonic-clonic seizure that starts in one side of the brain and spreads to affect both sides. It replaces the old term secondary generalised tonic-clonic seizure.

Previously, seizures were split into those that started in one side of the brain (focal seizures) and those that affect both sides of the brain from the start (generalised seizures). There was no overlap between the two groups. The new classification recognises that some types of seizures can be either focal or generalised. Examples of seizure types that can be either focal or generalised include atonic, tonic and myoclonic seizures.

Some new generalised seizure names have been introduced, including myoclonic-atonic and myoclonic-tonic-clonic. All the terms and seizure types are explained in the glossary.

What does this mean for me?

Some people whose seizures didn’t fit into the available categories in the old classification, might now be given a more accurate name for their seizures. 

But the new classification doesn’t mean you have to change the way you talk about your seizures, unless you want to. If you’ve always called your seizures partial seizures, for example, no one is saying you suddenly have to change this. 

But it’s important to know about the new names, so that if your doctor or epilepsy nurse uses them to describe your seizures, you know what they mean. You won’t find all healthcare professionals using the new classification straight away, but over time you might start to hear the new names being used.

Epilepsy Action is updating all its information to reflect the new names for seizure types. You can find more information on particular seizures and on how the new classification works on the Epilepsy Action website.


Absence seizure (Used to be called: petit-mal seizure)

In a typical absence seizure, you lose consciousness for a few seconds. You stop what you’re doing, but don’t fall. Absences which are not typical are called atypical. They last longer, and you may still be able to move around. 

Atonic seizure (Sometimes called drop attacks)

Your muscles go limp, usually making you drop to the floor. 

Focal seizure (Used to be called: partial seizure)

Any seizure that starts in one side of the brain. Also called a focal onset seizure

Focal aware seizure (Used to be called: simple partial seizure, or sometimes an aura)

A type of focal seizure where you remain aware of your surroundings throughout. 

Focal impaired awareness seizure (Used to be called: complex partial seizure)

A focal seizure where you lose awareness of what’s happening around you, even if only for a short time. 

Focal to bilateral tonic-clonic seizure (Used to be called: Secondary generalised tonic-clonic)

A seizure that starts in one side of the brain and then spreads to affect both sides of the brain. Some people who have this type of seizure get a ‘warning’ or ‘aura’ before they lose consciousness.

Generalised seizure

Any seizure that affects both sides of the brain from the start. Also called a generalised onset seizure.

Motor seizure

Any seizure that involves a change in your movement. For example, a tonic-clonic seizure, or a focal seizure where the main symptom is behaviour like plucking at your clothes or smacking your lips.

Myoclonic seizure

Sudden, short-lasting jerks that can affect some or all of your body.

Myoclonic-atonic seizure

An atonic seizure that starts with a myoclonic jerk – a sudden, short-lasting twitch or sharp movement.


A tonic-clonic seizure that starts with one or more myoclonic jerks (sudden sharp movements or twitches).

Non-motor seizure

Any seizure that doesn’t involve a change in your movement. For example, an absence seizure, or a focal seizure where the main symptom is a change in vision, smell or hearing.

Tonic seizure

Like the first phase of a tonic-clonic seizure, your muscles tighten and your body goes stiff. In a focal tonic seizure, your muscles tighten in just part of your body.

Tonic-clonic seizure (Used to be called: grand-mal seizures)

A seizure where you lose consciousness, your body goes stiff, you fall to the floor and all your muscles jerk. 

Unclassified seizure

A seizure that doctors are sure is an epileptic seizure, but can’t decide what type it is. This could be because they don’t have enough information about the seizure, or the symptoms of the seizure are unusual.

Unknown onset

When doctors aren’t sure what part of the brain a seizure started in.

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