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| __NOTOC__ | | __NOTOC__ |
| {{Seizure}} | | {{Seizure}} |
| {{CMG}} | | {{CMG}} {{AE}} {{SHA}} |
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| ==Overview== | | ==Overview== |
| The numerous epileptic [[seizure]] types are most commonly defined and grouped according to a scheme proposed by the [[International League Against Epilepsy]] (ILAE) in 1981.<ref name="ILEA1981">{{cite journal
| | In 2017, the [[International League Against Epilepsy]] (ILAE) classified [[seizure]] by its onsets as focal (aware/impaired awareness, motor, nonmotor, focal to tonic-clonic seizures), generalized (motor, nonmotor), and unknown (motor, nonmotor, and unclassified). In 1981, the [[International League Against Epilepsy]] (ILAE) classified epileptic [[seizures]] as [[Focal seizures|partial seizures]] ([[simple partial seizure]]s, [[complex partial seizure]]s, and [[partial seizures]] evolving to secondarily [[generalized seizures]]), [[Generalised epilepsy|generalized seizures]] ([[absence seizure]]s, [[myoclonic seizure]]s, [[clonic seizure]]s, [[Tonic |tonic]] seizures, [[tonic-clonic seizure]]s (grand mal), and [[atonic seizure]]s), and unclassified [[epileptic seizures]]. |
| | author =
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| | title = Proposal for revised clinical and electroencephalographic classification of epileptic seizures. From the Commission on Classification and Terminology of the International League Against Epilepsy.
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| | journal = Epilepsia
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| | volume = 22
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| | issue = 4
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| | pages = 489-501
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| | year = 1981
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| | id = PMID 6790275}}</ref> Distinguishing between seizure types is important since different types of seizure may have different causes, prognosis and treatments.
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| ==Classification== | | ==Classification== |
| There are many types of seizures. These can be classified into two broad groups:
| | '''In 2017, the [[International League Against Epilepsy]] (ILAE) classified seizures by their onsets as:'''<ref name="FisherCross2017">{{cite journal|last1=Fisher|first1=Robert S.|last2=Cross|first2=J. Helen|last3=D'Souza|first3=Carol|last4=French|first4=Jacqueline A.|last5=Haut|first5=Sheryl R.|last6=Higurashi|first6=Norimichi|last7=Hirsch|first7=Edouard|last8=Jansen|first8=Floor E.|last9=Lagae|first9=Lieven|last10=Moshé|first10=Solomon L.|last11=Peltola|first11=Jukka|last12=Roulet Perez|first12=Eliane|last13=Scheffer|first13=Ingrid E.|last14=Schulze-Bonhage|first14=Andreas|last15=Somerville|first15=Ernest|last16=Sperling|first16=Michael|last17=Yacubian|first17=Elza Márcia|last18=Zuberi|first18=Sameer M.|title=Instruction manual for the ILAE 2017 operational classification of seizure types|journal=Epilepsia|volume=58|issue=4|year=2017|pages=531–542|issn=00139580|doi=10.1111/epi.13671}}</ref><ref name="pmid26033084">{{cite journal| author=Stafstrom CE, Carmant L| title=Seizures and epilepsy: an overview for neuroscientists. | journal=Cold Spring Harb Perspect Med | year= 2015 | volume= 5 | issue= 6 | pages= | pmid=26033084 | doi=10.1101/cshperspect.a022426 | pmc=4448698 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26033084 }} </ref> |
| * Primary generalized seizures—seizures begin with widespread involvement of both sides of the brain. Generalized seizures are divided according to the effect on the body, but all involve loss of consciousness. These include absence, myoclonic, clonic, tonic, tonic–clonic, and atonic seizures.
| | *Focal (aware/impaired awareness) |
| * Partial seizures—seizures begin with involvement of a smaller, localized area of the brain. With some partial seizures, the disturbance can still spread within seconds or minutes to involve widespread areas of the brain (secondary generalized seizure). Partial seizures are further divided on the extent to which consciousness is affected (simple partial seizures means consciousness unaffected, and complex partial seizures means consciousness is affected).
| | ** Motor |
| ==International classification of seizure types (1981)==
| | *** [[Automatisms]] |
| | | *** [[Atonic]] |
| This classification is based on observation (clinical and [[EEG]]) rather than the underlying [[pathophysiology]] or [[anatomy]].
| | *** [[Clonic]] |
| | | *** [[Epileptic]] [[spasm]] |
| :'''I''' [[Focal seizures|Partial seizures]] (Older term: focal seizures)
| | *** [[Hyperkinetic]] |
| ::'''A''' [[Simple partial seizure]]s - consciousness is not impaired
| | *** [[Myoclonic]] |
| :::'''1''' With motor signs
| | *** [[Tonic]] |
| :::'''2''' With sensory symptoms
| | ** Nonmotor |
| :::'''3''' With autonomic symptoms or signs
| | *** [[Autonomic]] |
| :::'''4''' With psychic symptoms
| | *** [[Behavior]] arrest |
| ::'''B''' [[Complex partial seizure]]s - consciousness is impaired (Older terms: temporal lobe or psychomotor seizures)
| | *** [[Cognitive]] |
| :::'''1''' Simple partial onset, followed by impairment of consciousness
| | *** [[Emotional]] |
| :::'''2''' With impairment of consciousness at onset
| | *** [[Sensory]] |
| ::'''C''' Partial seizures evolving to secondarily generalized seizures
| | ** Focal to [[bilateral]] [[tonic-clonic]] seizures |
| :::'''1''' Simple partial seizures evolving to generalized seizures
| | * Generalized |
| :::'''2''' Complex partial seizures evolving to generalized seizures
| | ** Motor |
| :::'''3''' Simple partial seizures evolving to complex partial seizures evolving to generalized seizures
| | *** [[Tonic-clonic]] |
| :'''II''' [[Generalised epilepsy|Generalized seizures]]
| | *** [[Clonic]] |
| ::'''A''' [[Absence seizure]]s (Older term: petit mal)
| | *** [[Tonic]] |
| :::'''1''' Typical absence seizures
| | *** [[Myoclonic]] |
| :::'''2''' Atypical absence seizures
| | *** [[Myoclonic-tonic-clonic]] |
| ::'''B''' [[Myoclonic seizure]]s
| | *** [[Myoclonic-atonic]] |
| ::'''C''' [[Clonic seizure]]s
| | *** [[Atonia]] |
| ::'''D''' Tonic seizures
| | *** [[Epileptic]] [[spasm]] |
| ::'''E''' [[Tonic-clonic seizure]]s (Older term: grand mal)
| | ** Nonmotor (absence) |
| ::'''F''' [[Atonic seizure]]s
| | *** Typical |
| :'''III''' Unclassified epileptic seizures
| | *** Atypical |
| | | *** [[Myoclonic]] |
| In terms of their origin within the brain, seizures may be described as either ''partial'' (focal) or ''generalized''. Partial seizures only involve a localized part of the brain, whereas generalized seizures involve the the whole of both hemispheres. The term 'secondary generalisation' may be used to describe a partial seizure that later spreads to the whole of the cortex and becomes generalized.
| | *** [[Eyelid]] [[myoclonia]] |
| | | *Unknown |
| Whilst most seizures can be neatly split into partial and generalized, there exists some that don't fit. For example: the seizure may be generalized only within one hemisphere. Alternatively there may be many focal points (''multifocal seizures'') that are distributed in a symmetrical or asymmetrical pattern.
| | ** Motor |
| | | *** [[Tonic-clonic]] |
| ===Partial seizures=== | | *** [[Epileptic]] [[Spasm]] |
| | | ** Nonmotor |
| Partial seizures may be further subdivided into both simple and complex seizures. This refers to the effect of such a seizure on [[consciousness]]; simple seizures cause no interruption to consciousness (although they may cause sensory distortions or other sensations), whereas complex seizures interrupt consciousness to varying degrees. This does not necessarily mean that the person experiencing this sort of seizure will fall unconscious (like fainting). For example, a [[complex partial seizure]] may involve the unconscious repetition of simple actions, gestures or verbal utterances, or simply a blank stare and apparent unawareness of the occurrence of the seizure, followed by no memory of the seizure. Other patients may report a feeling of tunnel vision or dissociation, which represents a diminished awareness without full loss of consciousness. Still other patients can perform complicated actions, such as travel or shopping, while in the midst of a complex partial seizure.
| | *** [[Behavior]] arrest |
| | | ** Unclassified |
| The effects of partial seizures can be quite dependent on the area of the brain in which they are active. For example, a partial seizure in areas involved in perception may cause a particular sensory experience (for example, the perception of a scent, music or flashes of light) whereas, when centered in the [[motor cortex]], a partial seizure might cause movement in particular groups of [[muscle]]s. This type of seizure may also produce particular thoughts or internal visual images or even experiences which may be distinct but not easily described. Seizures centered on the [[temporal lobe]]s are known to produce [[mysticism|mystical]] or [[Religious ecstasy|ecstatic]] experiences in some people. These may result in a misdiagnosis of [[psychosis]] or even [[schizophrenia]], if other symptoms of seizure are disregarded and other tests are not performed. Unfortunately for those with epilepsy, [[anti-psychotic]] medications prescribed without [[anticonvulsant]]s in this case can actually lower the seizure threshold further and worsen the symptoms.
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| When the effects of a partial seizure appear as a 'warning sign' before a larger seizure, they are known as an [[aura (symptom)|aura]]: it is frequently the case that a partial seizure will spread to other parts of the brain and eventually become generalized, resulting in a tonic-clonic convulsion. The subjective experience of an aura, like other partial seizures, will tend to reflect the function of the affected part of the brain.
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| ===Generalized seizures===
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| Primarily generalized seizures can be sub-classified into a number of categories, depending on their behavioral effects:
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| * [[Absence seizure]]s involve an interruption to consciousness where the person experiencing the seizure seems to become vacant and unresponsive for a short period of time (usually up to 30 seconds). Slight muscle twitching may occur. | |
| * [[Myoclonic seizure]]s involve an extremely brief (< 0.1 second) muscle contraction and can result in jerky movements of muscles or muscle groups. | |
| * [[Clonic seizure]]s are myoclonus that are regularly repeating at a rate typically of 2-3 per second. | |
| * [[Tonic-clonic seizure]]s involve an initial contraction of the [[muscle]]s (tonic phase) which may involve [[tongue]] biting, [[urinary incontinence]] and the absence of [[Breath|breathing]]. This is followed by rhythmic muscle contractions (clonic phase). This type of seizure is usually what is referred to when the term 'epileptic fit' is used colloquially. | |
| * [[Atonic seizure]]s involve the loss of muscle tone, causing the person to fall to the ground. These are sometimes called 'drop attacks' but should be distinguished from similar looking attacks that may occur in [[narcolepsy]] or [[cataplexy]]. | |
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| ===Continuous seizures===
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| [[Status epilepticus]] refers to continuous seizure activity with no recovery between successive seizures. When the seizures are convulsive, it is a life-threatening condition and emergency medical assistance should be called immediately if this is suspected. A tonic-clonic seizure lasting longer than 5 minutes (or two minutes longer than a given person's usual seizures) is usually considered grounds for calling the emergency services. | |
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| [[Epilepsia partialis continua]] is a rare type of focal motor seizure ([[hand]]s and [[face]]) which recurs every few seconds or minutes for extended periods (days or years). It is usually due to strokes in adults and focal cortical inflammatory processes in children ([[Rasmussen's encephalitis]]), possibly caused by chronic [[viral infection]]s or [[autoimmune]] processes. | |
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| ==Future classifications==
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| In 1997, the ILAE began work on revising the classification of seizures, epilepsies and epileptic syndromes.<ref name="ILEA-Diagnostic">[http://www.ilae-epilepsy.org/Visitors/Centre/ctf/overview.cfm ILEA: A Proposed Diagnostic Scheme For People With Epileptic Seizures And With Epilepsy: Report Of The Ilae Task Force On Classification And Terminology]</ref> This revision remains in gestation and has not superseded the 1981 classification.
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| Proposed changes to terminology include:<ref name="ILEA-KeyTerms">[http://www.ilae-epilepsy.org/Visitors/Centre/ctf/table3.cfm ILEA: Defintions of Key Terms]</ref>
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| *Replace partial with the older term focal to describe seizures that originate in one part of the brain (though not necessarily a small or well defined area). The word partial was regarded as ambiguous. | |
| *Drop the terms simple partial and complex partial - grouping based on the effect to consciousness is no longer regarded as useful. | |
| *Replace cryptogenic with probably symptomatic. | |
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| The hierarchy presented has the structure:<ref name="ILEA-SeizureTypes">[http://www.ilae-epilepsy.org/Visitors/Centre/ctf/seizure_types.cfm ILEA: Seizure Types]</ref>
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| :'''Self limiting seizure types'''
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| ::'''''Generalized seizures'''''
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| :::Tonic-clonic seizures (includes variations beginning with a clonic or myoclonic phase)
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| :::Clonic seizures (with and without tonic features)
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| :::Typical absence seizures
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| :::Atypical absence seizures
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| :::Myoclonic absence seizures
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| :::Tonic seizures
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| :::Spasms
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| :::Myoclonic seizures
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| :::Massive bilateral myoclonus
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| :::Eyelid myoclonia (with and without absences)
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| :::Myoclonic atonic seizures
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| :::Negative myoclonus
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| :::Atonic seizures
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| :::Reflex seizures in generalized epilepsy syndromes
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| :::Seizures of the posterior neocortex
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| :::Neocortical temporal lobe seizures
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| ::'''''Focal seizures'''''
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| :::Focal sensory seizures
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| :::Focal motor seizures
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| :::Gelastic seizures
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| :::Hemiclonic seizures
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| :::Secondarily generalized seizures
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| :::Reflex seizures in focal epilepsy syndromes
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| :'''Continuous seizure types'''
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| ::'''''Generalized status epilepticus'''''
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| :::Generalized tonic-clonic status epilepticus
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| :::Clonic status epilepticus
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| :::Absence status epilepticus
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| :::Tonic status epilepticus
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| :::Myoclonic status epilepticus
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| ::'''''Focal status epilepticus'''''
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| :::Epilepsia partialis continua of Kojevnikov
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| :::Aura continua
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| :::Limbic status epilepticus (psychomotor status)
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| :::Hemiconvulsive status with hemiparesis
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| ==Earlier classifications==
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| The 1981 classification was a revision of the one devised by [[Henri Gastaut]] for the ILAE and published in 1970.<ref name="Gastaut1970">{{cite journal | author = Gastaut H | title = Clinical and electroencephalographical classification of epileptic seizures. | journal = Epilepsia | volume = 11 | issue = 1 | pages = 102-13 | year = 1970 | id = PMID 5268244}}</ref> A significant difference was the distinction between simple and complex partial seizures. In the 1970 classification, the distinction was whether the symptoms involved elementary sensory or motor functions (simple) or whether "higher functions" were involved (complex).
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| This was changed to consider whether consciousness was fully retained or not. As a result, studies that group patients according to these classifications are not directly comparable from one generation to another. The 1970 classification was important for standardizing the modern terms for many seizure types. Prior to this, terms such as petit mal, grand mal, Jacksonian, psychomotor, and temporal-lobe seizures were used.
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| The earliest classification of seizures can be attributed to Babylonian scholars who inscribed their medical knowledge into stone tablets know as the ''Sakikku'' (meaning ''All Diseases'').<ref name="Reynolds1990">{{cite journal | author = Wilson J, Reynolds E | title = Texts and documents. Translation and analysis of a cuneiform text forming part of a Babylonian treatise on epilepsy. | journal = Med Hist | volume = 34 | issue = 2 | pages = 185-98 | year = 1990 | url = http://www.pubmedcentral.nih.gov/picrender.fcgi?artinstid=1036070&blobtype=pdf | id = PMID 2187129}}</ref> This dates from the reign of the Babylonian king Adad-apla-iddina of the Second Dynasty of Isin - reckoned to be between 1067 and 1046 BC. Many types of seizures are described, each attributed to a certain demon or departed spirit and given a prognosis.
| | '''In 1981, the [[International League Against Epilepsy]] (ILAE) classified [[epileptic seizure]]s as:'''<ref name="pmid26033084">{{cite journal| author=Stafstrom CE, Carmant L| title=Seizures and epilepsy: an overview for neuroscientists. | journal=Cold Spring Harb Perspect Med | year= 2015 | volume= 5 | issue= 6 | pages= | pmid=26033084 | doi=10.1101/cshperspect.a022426 | pmc=4448698 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26033084 }} </ref><ref name="pmid6790275">{{cite journal| author=| title=Proposal for revised clinical and electroencephalographic classification of epileptic seizures. From the Commission on Classification and Terminology of the International League Against Epilepsy. | journal=Epilepsia | year= 1981 | volume= 22 | issue= 4 | pages= 489-501 | pmid=6790275 | doi=10.1111/j.1528-1157.1981.tb06159.x | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=6790275 }} </ref> |
| | * [[Focal seizures|Partial seizures]] (focal, local) |
| | ** [[Simple partial seizure]]s - [[consciousness]] is not impaired |
| | ** [[Complex partial seizure]]s - [[consciousness]] is impaired ([[temporal lobe]] or [[psychomotor]] seizures) |
| | ** [[Partial seizures]] evolving to secondarily [[generalized seizures]] |
| | * [[Generalised epilepsy|Generalized seizures]] - initial involvement of both [[hemispheres]], [[consciousness]] may be impaired |
| | ** [[Absence seizure]]s |
| | ** [[Myoclonic seizure]]s |
| | ** [[Clonic seizure]]s |
| | ** [[Tonic |Tonic]] seizures |
| | ** [[Tonic-clonic seizure]]s ([[Grand mal]]) |
| | ** [[Atonic seizure]]s |
| | * Unclassified [[epileptic seizures]] |
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| ==References== | | ==References== |
| {{reflist|2}} | | {{reflist|2}} |
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| [[Category:Neurology]] | | [[Category:Neurology]] |
| [[Category:Epilepsy]] | | [[Category:Epilepsy]] |
| [[Category:Emergency medicine]] | | [[Category:Emergency medicine]] |
| [[Category:Disease]] | | [[Category:Disease]] |
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| {{WH}}
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| {{WS}}
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