ILAE Classification of the Epilepsies

2025 ILAE Seizure Classification Framework

Focal

Focal seizures originate in networks limited to one hemisphere of the brain (they may later spread, but initial onset is localized). In the updated classification, focal seizures are further classified by the patient's state of consciousness during the seizure – either preserved or impaired.

Focal Preserved Consciousness (FPC)

A focal seizure in which consciousness remains intact – the person is aware of self and environment and responsive throughout the event. Previously referred to as a focal aware seizure.

Patients can often recall the event afterward
May include observable manifestations (autonomic features, motor activity)
Can include non-observable manifestations (sensory, cognitive, emotional)

Focal Impaired Consciousness (FIC)

A focal seizure where consciousness is impaired – the person has diminished awareness and responsiveness. Previously called "complex partial seizure."

Patient may have no memory for the event
May include automatisms (lip smacking, fumbling movements)
Can include observable motor phenomena (posturing, repetitive movements)
Often followed by postictal confusion

Focal-to-Bilateral Tonic-Clonic (FBTC)

A seizure that begins focally and then spreads to involve both hemispheres, resulting in a bilateral tonic-clonic seizure. Formerly called "secondary generalized tonic-clonic."

Always impairs consciousness during the tonic-clonic phase
Typically marked by an initial focal symptom or aura
Progresses to bilateral stiffening and jerking of limbs

Generalized Onset

Generalized seizures involve both hemispheres from the onset (the seizure activity is widely distributed across networks of the brain at start). Consciousness is typically impaired to some degree in generalized seizures, though for certain brief types awareness may be preserved.

Absence Seizures (AS)

Generalized non-motor seizures characterized primarily by brief impairment of consciousness (usually a sudden behavioral arrest and vacant stare). Typically last 5-20 seconds with abrupt onset and offset.

Typical Absence (TA): Classic absence seen in idiopathic generalized epilepsies with sudden pause, blank stare, and unresponsiveness, usually with 3 Hz generalized spike-wave EEG pattern
Atypical Absence (AA): Less abrupt onset/offset, often longer duration (20-30s), usually in context of Lennox-Gastaut syndrome with slower spike-wave (<2.5 Hz)
Myoclonic Absence (MA): Rhythmic myoclonic jerks accompany typical impairment of consciousness, often lasting 10-60 seconds
Eyelid Myoclonia: Brief bursts of eyelid jerking, often with upward eye deviation, may occur with or without impaired awareness

Generalized Tonic-Clonic Seizures (GTC)

Convulsive seizures featuring a sequence of tonic contraction followed by clonic jerking of the limbs ("grand mal"), with loss of consciousness

Myoclonic-Tonic-Clonic (MTC): GTC seizure beginning with one or more myoclonic jerks
Absence-Tonic-Clonic (ATC): GTC seizure that starts with an absence seizure before progressing to convulsion

Other Generalized Seizures

Generalized Myoclonic (GM): Sudden, brief, shock-like muscle jerks involving limbs or body, typically very brief
Generalized Clonic (GC): Rhythmic jerking movements without a preceding tonic phase, more common in infants
Generalized Negative Myoclonic (GNM): Brief losses of muscle tone due to interruption of muscle activity
Generalized Epileptic Spasms (GES): Sudden, brief contraction of axial and proximal muscles, often occurring in clusters
Generalized Tonic (GT): Sustained increase in muscle tone throughout the body, often seen in Lennox-Gastaut syndrome
Generalized Atonic (GA): Sudden loss of muscle tone, may cause drop attacks
Generalized Myoclonic-Atonic (GMA): Two-phase seizure where a myoclonic jerk is immediately followed by an atonic drop

Unknown

This category is used when it is unknown whether a seizure is focal or generalized in onset. Typically, this occurs if a seizure was unwitnessed or lacks sufficient data (e.g. occurred during sleep or without EEG) to determine the initial onset.

Unknown – Preserved Consciousness

A seizure of indeterminate onset during which consciousness was preserved (the person remained aware and responsive).

Used when a patient experiences symptoms without loss of awareness
Unclear if the seizure started focally or was generalized
Less common classification since preserved awareness often suggests focal origin

Unknown – Impaired Consciousness

A seizure of indeterminate onset in which consciousness was impaired. Applies when someone has a loss of awareness during the event but there's no information on how the seizure began.

Person may be found confused or unresponsive
No witness or data indicates whether it was a generalized or focal seizure
Interim classification until further workup clarifies the type

Unknown – Bilateral Tonic-Clonic (BTC)

A generalized tonic-clonic seizure of unknown onset. A convulsive seizure featuring tonic then clonic phases was observed, but it's uncertain if it began focally or was generalized from the start.

Commonly used when seizure onset wasn't witnessed
May be reclassified if subsequent EEG/imaging reveals focal onset
Interim category that should be updated when more information becomes available

Clinical Examples

Examples illustrating the practical application of the 2025 ILAE seizure classification

Unknown - Bilateral Tonic-Clonic (BTC)

A young woman awakens to find her 20-year-old boyfriend having a seizure in bed. The onset is not witnessed, but she is able to describe bilateral stiffening followed by bilateral "shaking." EEG and MRI findings are normal.

Classification: Bilateral tonic–clonic seizure—unknown whether focal or generalized (BTC)

Focal to Bilateral Tonic-Clonic (FBTC)

In an alternate scenario of the previous case, the EEG shows a clear right parietal slow-wave focus. The MRI shows a right parietal region of cortical dysplasia.

Classification: Focal to bilateral tonic–clonic seizure (FBTC)

Focal - Impaired Consciousness (FIC)

A 25-year-old woman describes seizures beginning with 30s of an intense feeling that "familiar music is playing." She can hear other people talking but afterward realizes that she could not determine what they were saying. Eyewitnesses report that the patient does not respond to external stimuli during the seizure.

Classification: Focal impaired consciousness seizure (FIC)

Evolution: Auditory aura → Receptive aphasia → Impaired responsiveness → Postictal confusion

Focal - Preserved Consciousness (FPC)

A 22-year-old man has seizures during which he remains fully aware, with the "hair on my arms standing on edge" and a feeling of being flushed.

Classification: Focal preserved consciousness seizure (FPC) with observable manifestations: piloerection + flushing

Generalized Myoclonic-Tonic-Clonic

A 13-year-old with juvenile myoclonic epilepsy has seizures beginning with a few jerks, followed by stiffening of all limbs and then rhythmic jerking of all limbs.

Classification: Generalized myoclonic-tonic–clonic seizures (GTC)

Generalized Epileptic Spasm

A 3-month-old boy has clusters of short seizures with flexion in the neck and hips, and abduction in the shoulders of short duration (up to 2s). Video-EEG showed epileptic spasms associated with a generalized suppression on EEG.

Classification: Generalized epileptic spasm (GES)

Focal Epileptic Spasms

A 14-month-old girl has sudden extension of both arms and flexion of the trunk for approximately 2s. These seizures repeat in clusters. EEG shows hypsarrhythmia with bilateral spikes, most prominent over the left parietal region. MRI shows left parietal cortical dysplasia.

Classification: Focal seizure with epileptic spasms (focal epileptic spasms)

FPC with Automatisms

During video-EEG monitoring, a 28-year-old female patient experiences an ascending sensation from the stomach and then starts chewing and manipulating nearby objects using the right hand. The patient can recall what happens and is able to respond.

Classification: Focal preserved consciousness seizure (FPC)

Evolution: Epigastric aura → Oroalimentary automatisms + gestural automatisms with preserved awareness

FBTC with Visual Aura

An 8-year-old boy reports episodes starting with seeing colored dots and stripes on the left side. Eyewitnesses report that he does not respond, turns his head to the left, becomes stiff, and then has jerks in all limbs.

Classification: Focal-to-bilateral tonic–clonic seizure (FBTC)

Evolution: Visual aura → Versive to left + loss of awareness → Bilateral tonic–clonic

FIC with Automatisms

A 33-year-old man experienced seizures accompanied by a feeling of abdominal discomfort followed by loss of awareness. His wife reported episodes of lip smacking, fumbling hand movements, and occasional right-hand posturing.

Classification: Focal impaired consciousness seizure (FIC)

Evolution: Epigastric aura → Impaired awareness → Oroalimentary automatisms + gestural automatisms + dystonic posturing

Examples adapted from the 2025 ILAE Classification of Epileptic Seizures

Color Code:

Focal

Generalized

Combined

Neonatal

Infant

Childhood

Adolescent

Variable Age

The ILAE Classification provides a framework for classifying seizures, epilepsies, and epilepsy syndromes. This page presents an overview of these classifications to help with the understanding and diagnosis of epilepsy.

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Epilepsy Syndromes with Onset in Neonates and Infants

Self‑Limited Neonatal Epilepsy (SeLNE)

Focal seizures starting between days 2 and 7 with normal development. Associated with KCNQ2KCNQ2 mutations affect potassium channels and are the most common cause of self-limited neonatal epilepsy. Most cases follow autosomal dominant inheritance. mutations.

Epileptic Spasms

Clusters of spasms with chaotic EEG and developmental regression. Peak onset 4-7 months.

Early Infantile Epileptic Encephalopathy (EIEE)

Severe neonatal encephalopathy with tonic seizures and suppression-burst on EEG. Also known as Ohtahara syndromeNamed after Dr. Shunsuke Ohtahara who first described it in 1976. Often evolves into West syndrome (infantile spasms) after 3-6 months..

Epilepsy of Infancy with Migrating Focal Seizures (EIMFS)

Multifocal, migrating focal seizures with onset before 6 months. Associated with KCNT1KCNT1 encodes a sodium-activated potassium channel. Mutations lead to gain of function and increased excitability. Other genes involved include SCN1A, SCN2A, and KCNQ2. mutations.

Dravet Syndrome

Begins with prolonged, often fever-triggered seizures in the first year. Associated with SCN1ASCN1A gene provides instructions for making sodium channel subunits. Mutations lead to impaired function of inhibitory interneurons, causing hyperexcitability. 90% of mutations occur de novo. mutations (80% of cases).

Self‑Limited Focal Epilepsies of Childhood

Self‑Limited Epilepsy with Centrotemporal Spikes (SeLECTS)

Focal centrotemporal seizures during sleep with remission by adolescence. Formerly called BECTSBenign Epilepsy with Centrotemporal Spikes (BECTS) or Rolandic Epilepsy. Name changed to Self-Limited Epilepsy with Centrotemporal Spikes in the 2017 ILAE classification to avoid the term "benign" as cognitive and behavioral issues can occur..

Self-Limited Epilepsy with Autonomic Seizures (SeLEAS)

Onset in early childhood of focal autonomic seizures that are often prolonged. Formerly known as Panayiotopoulos syndromeNamed after Dr. Chrysostomos P. Panayiotopoulos. Key features include ictal vomiting, pallor, and eye deviation. Despite often prolonged seizures (>30 minutes in 40% of cases), prognosis is excellent..

Childhood Occipital Visual Epilepsy (COVE)

Focal visual seizures with occipital EEG findings and favorable prognosis. Formerly called Gastaut typeNamed after Henri Gastaut. Distinguished from migraine by brief duration of visual symptoms (seconds to minutes), stereotypical appearance, and potential evolution to other seizure types. of childhood occipital epilepsy.

Photosensitive Occipital Lobe Epilepsy (POLE)

Focal visual seizures triggered by light with characteristic occipital EEG patterns. Strong female predominanceFemale predominance is a common feature of photosensitive epilepsies, possibly related to hormonal influences on neural excitability..

Generalized Epilepsies of Childhood

Childhood Absence Epilepsy (CAE)

Brief staring spells with classic 3 Hz spike‑and‑wave EEG activity. Peak onset 5-7 years with multiple daily episodesChildren may have dozens to hundreds of absence seizures per day, each lasting 5-30 seconds. Often misinterpreted as daydreaming or inattention. Can be provoked by hyperventilation in about 90% of patients..

Epilepsy with Eyelid Myoclonia (EEM)

Eyelid myoclonia, with or without absences, induced by eye closure and photic stimulation. Also called Jeavons syndromeNamed after Peter Jeavons who first described it in 1977. Features the triad of eyelid myoclonia with or without absences, eye-closure sensitivity, and photosensitivity. Often resistant to medications..

Epilepsy with Myoclonic Atonic Seizures (EMAtS)

Myoclonic and atonic seizures causing drop attacks with generalized EEG findings. Previously called Doose syndromeNamed after Hermann Doose who described it in 1970. Characterized by diverse seizure types, with myoclonic-atonic seizures being the hallmark. Children often have normal development before seizure onset..

Epilepsy with Myoclonic Absence (EMA)

Very rare childhood epilepsy syndrome with daily myoclonic absence seizures. Features rhythmic 3 Hz jerkingDuring seizures, there is rhythmic myoclonic jerking at 3 Hz, often involving the shoulders and arms, with concomitant impaired awareness. Seizures typically last 10-60 seconds and may cause progressive drop of arms. with impaired consciousness.

Idiopathic Generalized Epilepsies (IGE)

Juvenile Absence Epilepsy (JAE)

Brief impaired awareness episodes with >3 Hz spike‑and‑wave EEG. Distinguished from CAE by later onset (10-16 years)Unlike CAE, JAE features less frequent absences but >90% develop generalized tonic-clonic seizures. Absences are typically less frequent than in CAE but may be longer in duration. and frequent GTCs.

Juvenile Myoclonic Epilepsy (JME)

Adolescent-onset epilepsy with myoclonic jerks and generalized polyspike‑and‑wave EEG. Prominent morning jerksMyoclonic jerks typically occur within 1-2 hours after awakening and can be triggered by sleep deprivation, alcohol, and stress. JME has a strong genetic component and usually requires lifelong treatment. with high photosensitivity.

Epilepsy with Generalized Tonic–Clonic Seizures Alone (GTCA)

Isolated generalized tonic–clonic seizures with normal interictal EEG in up to 50% of cases. Often sleep-relatedGTCA seizures frequently occur shortly after awakening (within the first 2 hours) or during relaxation periods. About 80% of patients respond well to appropriate anti-seizure medications..

Epilepsy Syndromes with Onset at a Variable Age

Sleep-Related Hypermotor Epilepsy (SHE)

Brief hyperkinetic seizures during sleep with focal frontal EEG abnormalities. Formerly called NFLENocturnal Frontal Lobe Epilepsy was renamed to Sleep-Related Hypermotor Epilepsy in 2017 because: 1) seizures can occur during daytime sleep, 2) the origin isn't always frontal, and 3) the semiology is more accurately described as hyperkinetic rather than just nocturnal..

Familial Mesial Temporal Lobe Epilepsy (FMTLE)

Focal temporal seizures with a positive family history. Features psychic and autonomic aurasCommon aura types include déjà vu, jamais vu, epigastric rising sensations, and fear. Unlike sporadic MTLE, FMTLE is typically not associated with hippocampal sclerosis and has a better prognosis with many achieving seizure freedom on medication., often well-controlled.

Familial Focal Epilepsy with Variable Foci (FFEVF)

Focal seizures with variable localization among family members. Associated with DEPDC5DEPDC5 gene mutations account for about 12-37% of FFEVF cases. This gene is part of the mTOR pathway regulation, and mutations can lead to cortical malformations including focal cortical dysplasia. mutations.

Epilepsy with Auditory Features (EAF)

Focal seizures with auditory auras and possible temporal EEG abnormalities. Familial form associated with LGI1LGI1 (Leucine-rich Glioma Inactivated 1) gene mutations are found in about 50% of familial cases, known as Autosomal Dominant Lateral Temporal Lobe Epilepsy (ADLTLE), but are rare in sporadic cases. mutations.

Autoimmune Epilepsies

Various syndromes with autoimmune etiology, including anti-NMDARAnti-NMDA receptor encephalitis typically affects young women and features psychiatric symptoms, memory deficits, seizures, and movement disorders. It's often responsive to immunotherapy, with 80% of patients achieving good outcomes., anti-LGI1, and GAD65 antibody-associated epilepsies.

Progressive Myoclonus Epilepsies (PME)

Severe myoclonic seizures with progressive neurological decline. Includes Unverricht-Lundborg diseaseCaused by mutations in the CSTB gene encoding cystatin B. The most common PME in Europe, especially Finland. Characterized by stimulus-sensitive myoclonus and tonic-clonic seizures with onset at 6-16 years, followed by progressive neurological deterioration., Lafora disease, and others.

Rasmussen Syndrome (RS)

Intractable seizures with progressive hemiplegia and unilateral EEG abnormalities. Features epilepsia partialis continuaEpilepsia partialis continua is a form of ongoing focal motor seizure activity that may continue for extended periods (days to years). In Rasmussen syndrome, it frequently affects the face and hand. Hemispherectomy may be required for seizure control. and unilateral atrophy.