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Seizure Types by Name in the ILAE 2017 Classification System

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There are numerous possible names for seizure types in the new ILAE 2017 classification system, some of which are synonyms. The variety is a result of the multiple levels of classifying; the flexibility of the system; and the varying information doctors have about their patients’ seizures.  The tables below contain the names and main features of the most common seizure types based on this new naming system.    

Focal Seizure Names per ILAE 2017

The word focal in a seizure name implies a focal onset. Thus, it is not necessary to include the word onset in seizure typesthe name.  It is also optional whether or not to include the word motor or nonmotor in the seizure name if it specifies the actual type of sign(s) or symptom(s) that occur with the event.  For example, the term focal tonic seizure is a condensed option for the term focal motor tonic seizure.  Other than how a seizure starts out, there is flexibility in the naming at all levels.  The main deciding factors are supporting information and personal preference.

Seizure Name Seizure Features
Focal aware The onset is focal (in one side of the brain) with no change in awareness during the event.
Focal impaired awareness
Focal unaware
A change in awareness occurs during the event.
Focal motor (± aware or impaired awareness = unaware)
A motor sign(s) and/or symptoms(s) occurs with the seizure.  Specifying a change in the level of awareness at any point during the event is optional if known.

Focal ± motor atonic

Atony is the first most prominent feature.

Focal ± motor ± [aware or impaired awareness] automatisms

Automatisms are the first most prominent feature.

Focal ± motor ± [aware or impaired awareness] clonic

Clonus is the most prominent initial feature.

Focal ± motor epileptic spasms

Epileptic spasms are the earliest most prominent feature.

Focal ± motor ± [aware or impaired awareness] hyperkinetic

Hyperkinesia or hyperkinetic motor activity is the first most prominent feature.

Focal ± motor ± [aware or impaired awareness] myoclonic

Myoclonus or myoclonic muscle movement is the most prominent earliest feature.

 Focal ± motor ± [aware or impaired awareness] tonic

Tonic muscle contractions are the most prominent initial feature.
Focal nonmotor (± aware or impaired awareness = unaware)
A nonmotor sign(s) and/or symptoms(s) occurs as the first prominent feature of the seizure.

 Focal ± nonmotor (± aware or impaired awareness) autonomic  

An autonomic sign(s) or symptom(s) is the first prominent feature of the event.

Focal ± nonmotor (± aware or impaired awareness) behavior arrest 

Behavior arrest is the dominant feature throughout the seizure.

Focal ± nonmotor (± aware or impaired awareness) cognitive

The display of impaired cognition is the main earliest feature.

Focal ± nonmotor (± aware or impaired awareness) emotional

The experience of an emotion(s) is the chief earliest symptom during the event.

Focal ± nonmotor (± aware or impaired awareness) sensory

The experience of a sensation(s) due to stimulation of a part of the brain by the seizure activity is the most prominent earliest feature of the event.
Focal to bilateral tonic-clonic  The seizure starts in one side of the brain and spreads to involve both sides. It results in bilateral tonic followed by clonic muscle contractions.

Generalized Seizure Names per ILAE 2017

When focal is not a part of the seizure type name it is presumably of generalized onset unless the term, unknown onset, is a part of the name. The word generalized seizure implies a generalized onset.  Therefore, onset does not have to be included in the name. 

Seizures in this category also consist of subclasses based on whether or not the main signs or symptoms at the onset are motor or nonmotor.  In contrast to focal seizures though nonmotor is synonymous with absence.  When the features are nonmotor it is not necessary to include the word generalized in the seizure name.  The main two types of absence seizures are typical and atypical.  Including myoclonic or eyelid myoclonia in the absence name are options if either of those features is prominent along with typical absence ones.

Another distinction from focal seizures is there is no descriptor for awareness in this category.  The reason is there is some impairment of awareness to some degree during most (but not all) generalized seizures.  Thus, the word generalized or absence implies that awareness is impaired even though it may not be in all cases.

Seizure Name
Seizure Features
Generalized motor  

 

 

Generalized tonic-clonic

Generalized clonic

Generalized myoclonic

Generalized myoclonic-tonic-clonic


Generalized myoclonic-atonic 


Generalized atonic

Generalized epileptic spasms

 

 

Generalized nonmotor (Absence)
 

Typical absence

  

  

 

        

 

 

 

 

 

Atypical absence

 

The onset is in both sides of the brain with observed or presumed change in awareness and observed bilateral motor activity.

The motor activity is a sequence of tonic followed by clonic muscle contractions.

The motor activity is clonic muscle contractions.

The motor activity is myoclonic muscle contractions.

The motor activity is a sequence of three phases of muscle contractions.  They are myoclonic, tonic and clonic in that sequence.

The motor activity begins with a phase of myoclonus followed by a phase of atony.

The motor activity is atony or flaccidness.

The motor activity is sudden flexion, extension, or a combination of both, muscle contractions, mainly of the proximal limbs or torso.  They are longer in duration than myoclonic ones but shorter than tonic ones.

The onset is in both sides of the brain with observed or presumed change in awareness and absence features. 

The onset is sudden and consists of the cessation of ongoing activities (behavioral arrest).  The person has a blank stare and usually does not respond when spoken to.

Other signs and symptoms that might be a part of it include myoclonus, eyelid myoclonia, automatisms, or autonomic activities.

It usually lasts from a few seconds to 30 seconds.  Recovery is rapid.

It commonly occurs with other types of seizures, particularly generalized tonic-clonic ones.

It is most common between 3 and 15 years of age.  It decreases in frequency with age and is rare after the age of 30.

An absence seizure with more pronounced changes in muscle tone than a typical one, and which starts and ceases less abruptly.  The EEG activity during the event is also different from that of a typical absence seizure.

Unknown Onset Seizure Names per ILAE 2017

Unknown onset seizure is a category that denotes lack of knowledge about how a seizure starts out.  It buys time to glean a clearer picture. A change in the category from it to focal onset or generalized onset is appropriate if future knowledge supports the change.  The change might be on the basis of observation of recurrent seizures or better description of signs and/or symptoms by a patient or witness.

Seizure Name
Seizure Features
Unknown Onset Motor

Tonic-clonic

 

Epileptic spasms

  

Unknown Onset Nonmotor

Behavior arrest

 

 

A witness observes and describes tonic-clonic movements by the seizer but did not witness the seizure onset.  

A witness observes and describes epileptic spasms on the part of the seizer but did not witness the seizure onset.

 

A witness observes and describes behavior arrest but did not witness the beginning of the event.

Unclassified Seizures per ILAE

Unclassified is not really a term that truly connotes a type of seizure.  The term is more or less a weasel word, if you will, to substitute for limited knowledge about a suspected seizure with the hope that there will be more knowledge about it in the future.  It stands in for classifying an event thought to be a seizure at any level.  Keen observation and precise description of seizures are the key factors for limiting its use. Its use might also be temporary as knowledge changes.

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Seizure Types by Name in the ILAE 2017 Classification System

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