Epilepsy Classification

Primary Category

Epilepsy

P-Category

Secondary Category

S-Category

Authors:

Harshadayani Jagadish Kumar MBBS,
Anber Mahboob MBBS,
Junaid Kalia MD

Introduction

The 2017 ILAE classification of seizures, epilepsies, and epilepsy syndromes aims to group

seizures according to

clinical presentation and its origin in the brain. and

epilepsies according to

seizure type, age of onset, probability of remission, EEG findings, radiologic findings, and genetics.
An emphasis is now placed on etiology.

The epilepsy syndrome is a new addition to the current classification system and is defined as

“a cluster of features incorporating seizure types, EEG, and imaging that tend to occur together”.
Factors that contribute to epilepsy syndrome include

Age of onset
Remission
Triggers
Diurnal variation
Intellectual and psychiatric dysfunction
EEG findings
Imaging studies
Family history and genetics.

Evolution of Classification

The International League Against Epilepsy (ILAE) over the years has evolved the classification of epilepsy.

These are highlights

1981: Difference between partial or generalized seizures.

1985: Difference between idiopathic or symptomatic.

1989: Added cryptogenic epilepsies and termed them symptomatic.

2005: Updated seizure definition is a “transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain”

2014: ILAE redefined epilepsy as a “disease” and not as a“disorder”

Epilepsy is two unprovoked seizure events.
Epilepsy is diagnosed if an individual has seizure and his or her “brain demonstrates a pathologic tendency to have one unprovoked or reflex recurrent seizures.”
After the initial event the probability was considered to be at least 60% within the next 10 years.

Table 1: Expanded version of 2017 International League Against Epilepsy seizure type classification

Classification	Focal Onset	Generalised Onset	Unknown Onset	Unclassified Onset
Description	Originate from one hemisphere that may be localised or widely distributed.	Originates from more than one region of the brain.	Unknown onset	Seizure not under any of the previous classification
Awareness	Awake/Impaired awareness	Impaired	Awake/Impaired awareness	These seizures do not fall in a specific category or possible with new genetic and radiology information. Hence ILAE left an option for unclassified epilepsies.
Motor	- Tonic - Atonic - Clonic - Myoclonic - Automatisms - Epileptic Spasms - Hyperkinetic	- Tonic - Clonic - Tonic -Clonic - Atonic - Myoclonic - Myoclonic-tonic-clonic - Myoclonic-atonic - Epileptic spasms	- Tonic-clonic - Epileptic spasms	ㅤ
Nonmotor onset	- Autonomic - Cognitive - Behavior Arrest - Emotional - Sensory	- Typical - Atypical - Myoclonic - Eyelid Myoclonia	ㅤ	ㅤ
Evolution	Focal to bilateral Tonic-Clonic	ㅤ	ㅤ	ㅤ

Derived From: Fisher, Robert S. et al. “Operational Classification of Seizure Types by the International League Against Epilepsy: Position Paper of the ILAE Commission for Classification and Terminology.” Epilepsia 58.4 (2017): 522–530. Web.

Table 2: Focal vs Generalized vs Combined Onset in Epilepsy Classification

Classification	Focal Onset	Generalised Onset	Combined Onset
Description	One or more of the generalised seizures	One or more of the focal seizures	Combined generalised and focal epilepsy
Types	- Unifocal - Multifocal	- Myoclonic Jerks	- Lennox - Gastaut Syndrome - Dravet Syndrome
EEG	Focal slowing or epileptiform discharges	Generalised spike-wave activity	EEG findings of both generalised and focal epilepsy

Table 3: Classification of Epilepsy Syndromes

Epilepsy Syndromes	Idiopathic or Genetic Syndrome	Reflux Syndrome	Well-described Focal Syndrome
Description	Genetic or self	Seizures are provoked by a specific stimulus	Childhood epilepsy with centrotemporal spikes and panayiotopoulos syndrome.
Types	- Childhood Absence - Juvenile Absence - Juvenile Myoclonic - Generalised Tonic-clonic	- Generalised tonic-clonic - Photosensitive - Reading - Startle	- Focal motor hemifacial - Nocturnal focal motor evolving to bilateral tonic-clonic seizures. - Focal autonomic seizures.

Table 4: Etiological Classification of Epilepsy

Genetic	Genetic mutation either inherited or new, family history or syndromes
Infectious	Meningitis and Encephalitis-Neurocysticercosis, HIV, Cytomegalovirus, and cerebral toxoplasmosis
Metabolic	Secondary to a known metabolic disorder with seizures as one of the main symptom
Immune	anti-N-methyl-D-aspartate, anti-leucine-rich, glioma inactivated 1 encephalitis
Structural	Stroke, trauma, tumour, malformations of cortical development, and infection
Unknown	No clear etiology

Bibliography

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