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ILAE new seizure classification

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ILAE new seizure classification

The International League Against Epilepsy (ILAE) announced some new names for seizures in May 2017. Our Education, Information and Support Services Manager explains the new seizure classifications and the reasons behind the changes. In this blog, you’ll find the new general outline of basic seizure classification.

With ILAE updating their seizure classifications, it's vital that health care professionals and people with epilepsy understand the new classification system and the new terminology used.

Many words for seizures that we've got used to using such as grand mal, petit mal and partial seizures were used as general terms to refer to any big or small seizure. With ILAE reworking and creating new groupings for seizures, we now have a different and more complete picture of all the different seizure types.

Seizures are now divided into groups depending on:

  • where they start in the brain (onset)
  • whether or not a person's awareness is affected
  • whether or not seizures involve other symptoms, such as movement
  • Depending on where they start, seizures are described as being focal onset, generalised onset or unknown onset.

What is a focal onset seizure?

One of the new groupings is focal onset seizures which start in one part of the brain and may affect a large part of one hemisphere or just a small area in one of the lobes. 

Here's our flowchart showing a breakdown of a focal onset seizure with information on the new classifications:

Seizure classifications - infographic

What is a generalised seizure?

The grouping 'generalised onset' covers seizures which affect both sides of the brain at once and happen without warning.

Here's our flowchart showing a breakdown of a generalised onset seizure with information on the new classifications:

seizure classification

What are the different seizures now called?

Here's all the different seizures and what they've now been called:

Focal aware seizures

Previously called partial seizures. In these seizures the person is conscious (aware and alert), will usually know that something is happening and will remember the seizure afterwards.

Focal impaired awareness seizures 

Previously called complex partial seizures. In these seizures the person’s consciousness is affected and they may be confused. They might be able to hear you, but not fully understand what you say or be able to respond to you. 

Generalised onset seizures

These seizures affect both sides of the brain at once and happen without warning.

Tonic clonic seizures

The seizure most people will recognise, where a person will jerk and shake as their muscles relax and tighten.

Atonic seizures (sometimes called drop attacks) and tonic seizure

In an atonic seizure the person’s muscles suddenly relax and they become floppy, and they oftern fall, usually forwards.

In a tonic seizure the person's muscles suddenly become stiff and they often fall, usually backwards.

Myoclonic seizures

Myoclonic means ‘muscle jerk’. Muscle jerks are not always due to epilepsy (for example, some people have them as they fall asleep).

Absence seizures

Absence seizures (previously called petit-mal) are typical absences or atypical absences. During a typical absence the person becomes blank and unresponsive for a few seconds. Atypical absences are similar to typical absences but they start and end more slowly, and last a bit longer.

These classifications now reflect our increased knowledge of seizures and seizure types, give clear guidelines for health care professionals and give an easier analysis of how a person's affected and where the seizure starts.

Our types of seizures section on our website has now been updated with more in-depth information to reflect the new classification system. 

Epileptic seizures

There are many different types of epileptic seizure. Any of us could potentially have a single epileptic seizure at some point in our lives. This is not the same as having epilepsy, which is a tendency to have seizures that start in the brain. 


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