Self-Limited & Absence Epilepsies
Self-Limited & Absence Epilepsies of Childhood
What Do You Need to Know?
- Febrile seizures: Most common childhood seizure type (2–5%); simple FS carry epilepsy risk of 1–2% (same as general population); no routine EEG/imaging per AAP; FEBSTAT links prolonged febrile SE → MTS → TLE
- SeLECTS: Most common childhood focal epilepsy (15–25%); centrotemporal spikes with horizontal dipole; hemifacial sensorimotor seizures from sleep; remission by age 16 in virtually all
- CAE vs JAE: CAE = dozens of absences/day, 3 Hz spike-wave, HV provokes >90%, 60–70% remit; JAE = less frequent absences, 80% GTC, typically lifelong treatment
- CSWS/ESES: EEG pattern (SWI ≥50%) drives encephalopathy, NOT seizure frequency; overnight EEG is mandatory; treat with high-dose benzodiazepine pulse → corticosteroids
- Drugs to AVOID in absence: CBZ, OXC, PHT, VGB — worsen absence seizures and may precipitate absence status
- GRIN2A: Genetic link across the SeLECTS → LKS → CSWS spectrum (10–20% of CSWS/LKS)
Febrile Seizures
Simple vs Complex Febrile Seizures
| Feature | Simple FS | Complex FS |
|---|---|---|
| Duration | <15 minutes | ≥15 minutes (febrile SE if ≥30 min) |
| Focal features | No — generalized (GTC) | Yes — clonic activity lateralized, eye deviation |
| Recurrence within 24 h | Single episode only | >1 seizure in the same febrile illness |
| Frequency | ~70–75% of all FS | ~25–30% of all FS |
| Risk of epilepsy | 1–2% (same as general population) | 4–6% (up to 10% with multiple complex features) |
| Todd paralysis | No | May occur after prolonged focal seizures |
Recurrence Risk Factors
- Age <18 months at first febrile seizure (strongest predictor)
- Lower temperature at the time of seizure
- Shorter duration of fever before seizure onset
- Family history of febrile seizures (first-degree relative)
- Complex features on the initial seizure
- Overall recurrence rate: ~1/3 of children with a first FS
Investigation — AAP Guidelines
- Simple FS: No routine EEG, no neuroimaging, no labs
- LP: Consider if age 6–12 months with incomplete immunization or if meningeal signs present
- Complex FS: Consider EEG if focal/prolonged/recurrent; MRI if abnormal neuro exam or developmental delay
- Antipyretics do NOT prevent FS recurrence; continuous daily ASM prophylaxis NOT recommended
FEBSTAT Study
- Prolonged febrile seizures (≥30 min) → acute hippocampal injury (T2 signal on MRI)
- Subset develops mesial temporal sclerosis (MTS) → temporal lobe epilepsy (TLE)
- Supports the “two-hit” hypothesis: prolonged febrile SE + predisposed brain → MTS → drug-resistant TLE
SeLECTS (Self-Limited Epilepsy with Centrotemporal Spikes)
Key Features
- Formerly: BECTS / benign rolandic epilepsy
- Most common childhood focal epilepsy — 15–25% of all childhood epilepsies
- Onset: 4–10 years (peak 7–10); slight male predominance
- Remission in virtually all by age 16; EEG normalizes after clinical remission
Seizure Semiology
- Hemifacial sensorimotor seizures: unilateral clonic jerking of face/mouth, tingling of tongue/lips/cheek
- Drooling (sialorrhea) and speech arrest (anarthria) with preserved consciousness
- Often from sleep (drowsiness or NREM); may secondarily generalize during sleep
- Brief: 30 sec to 2 min; infrequent (most have <10 lifetime seizures)
EEG
- Centrotemporal spikes: high-amplitude, biphasic/triphasic sharp waves at C3/C4 or C5/C6
- Horizontal dipole: negative over temporal, positive over frontal (board favorite)
- Sleep-activated: spike frequency markedly increases in NREM sleep
- Bilateral independent in ~30%; normal background (essential to distinguish from encephalopathies)
Treatment
- Many children require no treatment (infrequent, nocturnal, self-limited)
- If treatment needed: LEV, CBZ, OXC (sulthiame in Europe)
- Discontinue after 1–2 years seizure-free or by age 14–16
- Avoid overtreatment — overtreatment carries more risk than the epilepsy itself
Atypical Evolution of SeLECTS
- A small subset may develop more frequent seizures, cognitive decline, and EEG features of CSWS/ESES
- Red flags: language regression, behavioral deterioration, declining school performance
- If suspected → obtain overnight EEG to assess for spike-wave activation in sleep
- Presence of GRIN2A variants associated with higher risk of atypical evolution
Panayiotopoulos Syndrome (Self-Limited Epilepsy with Autonomic Seizures)
Key Features
- Second most common self-limited focal epilepsy after SeLECTS; onset 3–6 years
- Ictus emeticus: nausea and vomiting in ~80% of seizures — most characteristic feature
- Other autonomic features: pallor, flushing, mydriasis, incontinence
- Progressive obtundation; eye/head deviation; may evolve to hemiconvulsions or GTC
- Often prolonged: >30 min in one-third → autonomic status epilepticus
- Despite prolonged seizures, prognosis remains excellent
EEG
- Shifting, multifocal spikes — location may change between recordings
- Occipital predominance common but NOT required; sleep-activated; normal background
Prognosis & Treatment
- Universal remission within 1–2 years; most have <5 total seizures
- Treatment often not needed; rescue benzodiazepine plan is essential given risk of prolonged seizures
- If ASM needed: CBZ, OXC, or LEV
- Key to management: accurate diagnosis + parental reassurance (presentation mimics gastroenteritis, migraine, or encephalitis)
Gastaut-Type Childhood Occipital Visual Epilepsy
Key Features
- Peak onset 8–9 years; brief visual seizures are the hallmark
- Elementary visual hallucinations: multicolored circles/spots, one hemifield, seconds to minutes
- Ictal blindness: transient visual loss during or after hallucination
- Postictal migrainous headache — often misdiagnosed as migraine with aura
- EEG: occipital spikes; fixation-off sensitivity; sleep-activated; normal background
Seizure vs Migraine Aura
| Feature | Occipital Seizure | Migraine Aura |
|---|---|---|
| Duration | Seconds to 1–3 minutes | 5–60 minutes (gradual build) |
| Onset | Abrupt | Gradual (marching) |
| Visual features | Multicolored circles/spots | Black-and-white zigzag, scintillating scotoma |
| Headache | Postictal | Follows aura |
| EEG | Occipital spikes | Usually normal |
Treatment & Prognosis
- CBZ, OXC, or LEV — usually effective
- Most remit; small subset persists into adolescence (less universally self-limited than SeLECTS/Panayiotopoulos)
Comparison of Self-Limited Focal Epilepsies
| Feature | SeLECTS | Panayiotopoulos | Gastaut-Type |
|---|---|---|---|
| Peak onset | 7–10 years | 3–6 years | 8–9 years |
| Semiology | Hemifacial clonic, drooling, speech arrest; nocturnal | Autonomic (ictus emeticus); prolonged | Multicolored visual hallucinations; postictal headache |
| EEG | Centrotemporal spikes, horizontal dipole | Multifocal/shifting (often occipital) | Occipital spikes, fixation-off sensitivity |
| Duration | Brief (30 sec–2 min) | Often >30 min in 1/3 | Brief to moderate |
| Total seizures | <10 in most | <5 in most | Variable; may be frequent |
| Remission | Universal by age 16 | Universal; within 1–2 years | Highly likely; small subset persists |
| Treatment | Often not needed; LEV/CBZ/OXC | Often not needed; rescue BZD plan | Usually treated; CBZ/OXC/LEV |
GRIN2A — The SeLECTS–LKS–CSWS Spectrum
- GRIN2A encodes the GluN2A subunit of the NMDA receptor
- Pathogenic variants link a phenotypic spectrum:
- Mild: SeLECTS (typical, self-limited)
- Intermediate: Landau-Kleffner syndrome (acquired aphasia)
- Severe: CSWS/ESES (global cognitive regression)
- Found in 10–20% of CSWS/LKS cases
- Any child with SeLECTS who develops language regression → evaluate for atypical evolution; overnight EEG mandatory
CAE vs JAE — Absence Epilepsies
Comparison Table
| Feature | CAE | JAE |
|---|---|---|
| Onset | 4–10 years (peak 5–7) | 9–13 years (peak 10–12) |
| Absence frequency | Very frequent — dozens to hundreds/day | Less frequent — several/week to few/day |
| GTC seizures | 15–30% (usually in adolescence) | ~80% (often the presenting seizure type) |
| Myoclonic jerks | Not part of the syndrome | ~15–25%; if prominent → consider JME |
| EEG ictal | 3 Hz (2.5–4 Hz) generalized spike-wave | 3–5.5 Hz spike-wave or polyspike-wave |
| HV provocation | >90% of untreated patients | Effective but less reliable |
| Photosensitivity | ~10% | ~15–25% |
| Remission | 60–70% by adolescence | <20% remit off medication |
| ILAE 2022 | Self-limited | Not self-limited |
| First-line ASM | Ethosuximide (if no GTC) | Valproate (broad-spectrum) |
ILAE 2022 Diagnostic Criteria for CAE
- Mandatory: Onset 4–10 y; frequent typical absences (usually daily); 2.5–4 Hz GSW; normal development and neuro exam
- Exclusion: Myoclonic seizures, eyelid myoclonia, tonic/atonic/focal seizures, intellectual disability, GTC at onset
- GTC may develop later in a minority — does not exclude diagnosis if absent at onset
Treatment of Absence Epilepsy
Ethosuximide (SANAD II = First-Line for CAE Without GTC)
- Mechanism: T-type calcium channel blocker
- ~70% seizure freedom at 12 months (equal to VPA, superior to LTG)
- Better attentional performance than VPA — important for school-age children
- Effective ONLY for absence seizures — does NOT protect against GTC
- Side effects: GI (nausea, vomiting); rare SJS, blood dyscrasias
VPA Teratogenicity Concern
- 9–11% major congenital malformations (highest of all ASMs)
- Dose-dependent IQ reduction: 7–10 points lower; increased autism risk
- FDA pregnancy category X for migraine/bipolar; requires pregnancy prevention counseling
- Alternatives for women: lamotrigine, levetiracetam
Drugs That WORSEN Absence Seizures
- CBZ and OXC — may increase absence frequency or precipitate absence status
- PHT, VGB; also tiagabine, gabapentin, pregabalin
- Accurate syndrome classification BEFORE treatment is critical — misclassifying absences as focal impaired awareness seizures → Na channel blocker → paradoxical worsening
CSWS / ESES
Definition
- ESES = the EEG pattern — near-continuous spike-wave during NREM sleep
- CSWS = the clinical syndrome — ESES + global cognitive/behavioral regression + seizures
- DEE-SWAS = ILAE 2022 umbrella term (encompasses CSWS and LKS)
- Spike-wave index (SWI): ≥50% during NREM (classically ≥85% for “classic” CSWS)
The EEG Pattern Drives the Encephalopathy
- Cognitive regression driven by the ESES pattern during sleep, NOT seizure frequency
- Seizures may be infrequent or absent — child still regresses
- Treatment must target the EEG pattern, not just clinical seizures
EEG & Diagnosis
- NREM: Near-continuous bilateral spike-wave (1.5–3 Hz); SWI ≥50%
- REM: Marked attenuation of discharges (key diagnostic feature)
- Overnight EEG is MANDATORY — routine 30-min awake EEG misses the pattern
- Loss of normal sleep spindles and K-complexes in severe cases
Etiology
- Genetic: GRIN2A in 10–20%; also KCNQ2, CNKSR2, SLC6A1; 15q11.2-13.1 duplication
- Structural: Thalamic lesions (perinatal thalamic injury) strongly associated — thalamus generates and propagates sleep oscillations
- Also: polymicrogyria, focal cortical dysplasia, porencephaly, shunted hydrocephalus
- May evolve from atypical SeLECTS (rare but important)
- Substantial proportion remain of unknown etiology (likely undiscovered genetic causes)
Clinical Features
- Cognitive regression: global — language, executive function, visuospatial, memory, attention
- Behavioral: hyperactivity, aggression, impulsivity (may be presenting complaint)
- Motor: ataxia, dyspraxia, epileptic negative myoclonus in some
- Seizures: variable (focal motor, atypical absences, atonic, GTC) — may be infrequent or absent
Treatment Algorithm
- Step 1: High-dose oral diazepam pulse at bedtime (0.5–1.0 mg/kg × 3–4 weeks)
- Step 2: Corticosteroids (oral prednisolone 1–2 mg/kg/day or IV methylprednisolone pulses)
- Step 3: ACTH, IVIg, or ketogenic diet for refractory cases
- Step 4: Epilepsy surgery if focal structural lesion identified
- Adjunctive ASMs: VPA, ethosuximide, clobazam, LEV
Landau-Kleffner Syndrome (Acquired Epileptic Aphasia)
Key Features
- Acquired auditory verbal agnosia in a previously normally developing child; onset 3–8 years
- Loss of comprehension of spoken language; child may appear deaf
- Receptive loss precedes or accompanies expressive loss
- Seizures in ~70–80% but often infrequent; seizure severity does NOT correlate with language regression
- EEG: spike-wave over temporal/perisylvian regions; ESES pattern with temporal predominance
LKS vs CSWS Comparison
| Feature | LKS | CSWS |
|---|---|---|
| Cognitive deficit | Selective — acquired aphasia (auditory verbal agnosia) | Global — language + executive + visuospatial + motor |
| EEG topography | Temporal/perisylvian predominance | Diffuse or frontal predominance |
| Motor involvement | Uncommon | May include ataxia, dyspraxia, motor regression |
| Seizure frequency | Often infrequent or absent | More frequent; multiple seizure types |
| Age of onset | 3–8 years | 2–12 years |
| Recovery | Partial language recovery common; complete less frequent | Variable; depends on etiology and treatment timing |
Treatment
- Same stepwise approach as CSWS: benzodiazepine pulse → corticosteroids → ACTH/IVIg
- Multiple subpial transections (MSTs): surgical option for refractory LKS
- MSTs disrupt horizontal cortical connections while preserving vertical columnar function
- Resective surgery for patients with identifiable focal structural lesions
- Earlier treatment associated with better language outcomes; delays in recognition are common and detrimental
- Neurodevelopmental and educational support is critical even after seizure remission
Jeavons Syndrome (Eyelid Myoclonia with Absences)
Key Features
- Eyelid myoclonia on eye closure: rapid eyelid fluttering + upward eye deviation ± brief absence
- Nearly 100% photosensitive — seizures provoked by eye closure and photic stimulation
- EEG: generalized polyspike-and-wave (3.5–6 Hz) triggered by eye closure and photic stimulation
- Onset in childhood; typically NOT self-limited; drug-resistant in 40–50%
Treatment & Self-Induced Seizures
- VPA is first-line; alternatives: LEV, LTG (caution — may worsen myoclonus); avoid CBZ/OXC/PHT
- Lifelong photosensitivity management required
- Self-induced seizures: patients may deliberately seek flickering lights or wave fingers before eyes
- This is an epileptic phenomenon, NOT behavioral — often misinterpreted as attention-seeking
Board Pearls
💎 Board Pearl
- Simple febrile seizure + normal child = reassure. No EEG, no imaging, no daily ASM. Antipyretics do NOT prevent recurrence. Epilepsy risk is 1–2% (same as general population).
- Centrotemporal spikes + horizontal dipole + sleep-activated + normal background = SeLECTS. Most common childhood focal epilepsy. Treatment often unnecessary. Remission by age 16.
- Ictus emeticus in a young child = think Panayiotopoulos. Seizures often prolonged (>30 min in 1/3) but prognosis is excellent. Do not mistake for gastroenteritis.
- Hyperventilation provokes absences in >90% of untreated CAE. Have the child HV for 3–5 min during EEG. Failure to provoke suggests wrong diagnosis or effective treatment.
- CBZ/OXC/PHT/VGB worsen absence seizures. Always classify the syndrome before starting treatment. Misdiagnosis → Na channel blocker → paradoxical worsening or absence status.
- Cognitive regression in a child with epilepsy = overnight EEG. Routine awake EEG misses ESES. The EEG pattern (not seizure frequency) drives CSWS encephalopathy.
- GRIN2A links SeLECTS → LKS → CSWS. Same gene, phenotypic spectrum. SeLECTS + language regression → evaluate for atypical evolution (10–20% of CSWS/LKS).
Clinical Pearls
Clinical Pearl
Ethosuximide vs Valproate for CAE (SANAD II): Both achieve ~70% seizure freedom at 12 months (superior to lamotrigine). Ethosuximide preferred first-line when GTC absent due to better attentional performance and no teratogenicity risk. Valproate preferred when GTC coexist. For women of childbearing potential, VPA teratogenicity (9–11% MCM, 7–10 point IQ reduction) makes alternatives essential.
Clinical Pearl
Autonomic SE in Panayiotopoulos: Despite lasting >30 minutes, autonomic SE has excellent prognosis with no long-term cognitive sequelae. Acute treatment with rescue benzodiazepines is still indicated. A clear seizure action plan prevents both parental panic and undertreatment of prolonged events.
Clinical Pearl
LKS can present before seizures are recognized. A previously normal child with acquired auditory verbal agnosia should have an overnight EEG even if no seizures observed. Language regression may precede clinical seizures. Early aggressive treatment of the ESES pattern offers the best chance of language recovery.
References
- Specchio N, Wirrell EC, Scheffer IE, et al. ILAE classification and definition of epilepsy syndromes with onset in childhood. Epilepsia 2022;63(6):1398–1442.
- Hirsch E, French J, Scheffer IE, et al. ILAE definition of the idiopathic generalized epilepsy syndromes. Epilepsia 2022;63(6):1475–1499.
- Subcommittee on Febrile Seizures, AAP. Neurodiagnostic evaluation of the child with a simple febrile seizure. Pediatrics 2011;127(2):389–394.
- Shinnar S, Bello JA, Chan S, et al. MRI abnormalities following febrile status epilepticus in children: the FEBSTAT study. Neurology 2012;79(9):871–877.
- Glauser TA, Cnaan A, Shinnar S, et al. Ethosuximide, valproic acid, and lamotrigine in childhood absence epilepsy. Epilepsia 2013;54(1):141–155.
- Marson A, Burnside G, Appleton R, et al. The SANAD II study for newly diagnosed generalised and unclassifiable epilepsy. Lancet 2021;397(10282):1375–1386.
- Lesca G, Rudolf G, Bruneau N, et al. GRIN2A mutations in acquired epileptic aphasia and related childhood focal epilepsies. Nat Genet 2013;45(9):1061–1066.
- van den Munckhof B, de Vries EE, Braun KPJ, et al. Treatment of electrical status epilepticus in sleep: a pooled analysis of 575 cases. Epilepsia 2015;56(11):1738–1746.
- Landau WM, Kleffner FR. Syndrome of acquired aphasia with convulsive disorder in children. Neurology 1957;7(8):523–530.
- Panayiotopoulos CP. Benign childhood focal seizures and related epileptic syndromes. In: A Clinical Guide to Epileptic Syndromes and Their Treatment. 2nd ed. Springer; 2010.
- Caraballo RH, Cersosimo RO, Fejerman N. Childhood occipital epilepsy of Gastaut. Epilepsia 2008;49(2):288–297.
- Tassinari CA, Rubboli G, Volpi L, et al. Encephalopathy with ESES. Clin Neurophysiol 2000;111(Suppl 2):S94–S102.