Residency · Residency · Neurology
Febrile Seizures and Childhood Epilepsy Syndromes
Introduction
Childhood epilepsy syndromes represent a diverse group of disorders defined by characteristic seizure types, age of onset, EEG patterns, and prognosis. Understanding these syndromes is essential because accurate syndromic diagnosis determines treatment selection, genetic counseling, and prognostic discussions with families. Febrile seizures, the most common seizure type in childhood, serve as an important entry point for understanding the interplay between genetic predisposition and developmental factors.
Febrile Seizures
Definition and Classification
Febrile seizures are seizures occurring in children aged 6 months to 5 years, associated with fever (temperature 38 degrees C or higher) without CNS infection or other defined cause. Simple febrile seizures are generalized tonic-clonic, last less than 15 minutes, do not recur within 24 hours, and produce no postictal focal deficits. Complex febrile seizures have focal features, last 15 minutes or longer, recur within 24 hours, or are followed by postictal Todd paralysis.
Epidemiology and Prognosis
Febrile seizures affect 2-5% of children with peak incidence at 12-18 months. There is a strong genetic predisposition with family history present in 25-40% of cases. The risk of recurrence is approximately 30-35% after a first febrile seizure. The risk of subsequent epilepsy is 2-4% after simple febrile seizures (slightly higher than the general population risk of 1%) and 6-8% after complex febrile seizures.
Management
Acute management involves benzodiazepines (rectal diazepam or intranasal midazolam) for seizures lasting longer than 5 minutes. Continuous antiseizure medication is not recommended for simple febrile seizures. Intermittent diazepam at the onset of febrile illness may be considered for children with frequent recurrences. Lumbar puncture should be considered in infants 6-12 months (especially if unvaccinated) and any child with meningeal signs. Neuroimaging and EEG are not routinely indicated after a simple febrile seizure.
Self-Limited Childhood Epilepsy Syndromes
Self-Limited Epilepsy with Centrotemporal Spikes (Benign Rolandic Epilepsy)
This is the most common childhood epilepsy syndrome, accounting for 15-25% of childhood epilepsies, with onset between 3 and 13 years and peak at 7-10 years. Seizures are focal motor involving the face and oropharynx, manifesting as hemifacial twitching, drooling, dysarthria, and speech arrest, often occurring during drowsiness or sleep. Secondary generalization to tonic-clonic seizures may occur. The EEG shows centrotemporal (rolandic) spikes activated by sleep with a normal background. The prognosis is excellent, with remission by mid-adolescence in nearly all patients. Many children do not require antiseizure medication; if treatment is needed, levetiracetam or oxcarbazepine are preferred.
Childhood Absence Epilepsy (CAE)
CAE has onset between 4 and 10 years (peak 5-7 years) with female predominance. Seizures are typical absences consisting of brief staring spells lasting 5-20 seconds with abrupt onset and offset, occurring up to hundreds per day, and may have subtle automatisms such as eyelid fluttering or lip smacking. They are provoked by hyperventilation in nearly all untreated patients. The EEG shows generalized 3 Hz spike-and-wave discharges on a normal background. Ethosuximide is first-line for absence-only epilepsy, with valproic acid as an alternative. Carbamazepine, phenytoin, and gabapentin must be avoided as they can worsen absence seizures. The prognosis shows 60-70% remission by adolescence, with 10-15% developing generalized tonic-clonic seizures (juvenile absence epilepsy).
Panayiotopoulos Syndrome
This syndrome has onset between 3 and 6 years. Seizures feature predominant autonomic symptoms including nausea, retching, vomiting, pallor, and flushing, and may progress to eye deviation and impaired awareness. Prolonged seizures (autonomic status epilepticus) are common. EEG shows occipital spikes, though multifocal or shifting spikes may occur. The condition is self-limited with remission within 1-2 years of onset.
Severe (Developmental and Epileptic) Encephalopathies
| Syndrome | Age of Onset | Key Seizure Types | EEG Pattern | Treatment | Prognosis |
|---|---|---|---|---|---|
| Infantile spasms (West) | 3-12 months | Epileptic spasms in clusters | Hypsarrhythmia | ACTH; vigabatrin (if TSC) | Guarded; may progress to LGS |
| Lennox-Gastaut | 1-8 years | Tonic, atonic (drops), atypical absence | Slow (<2.5 Hz) spike-wave; GPFA | VPA, clobazam, rufinamide, CBD | Drug-resistant; lifelong seizures |
| Dravet | 5-8 months | Prolonged febrile/afebrile hemiclonic; later multiple types | Initially normal; later multifocal | VPA, clobazam, stiripentol, CBD, fenfluramine | High SUDEP risk; cognitive decline |
Infantile Epileptic Spasms Syndrome (Formerly West Syndrome)
This syndrome has onset at 3-12 months (peak 4-6 months) and is defined by the triad of epileptic spasms (brief symmetric or asymmetric flexion/extension movements in clusters), hypsarrhythmia on EEG (chaotic, high-amplitude, disorganized background with multifocal spikes), and developmental regression. Etiologies include structural causes (tuberous sclerosis, cortical malformations), genetic causes (many genes including ARX, CDKL5, STXBP1), metabolic causes, and unknown causes. Treatment is ACTH (adrenocorticotropic hormone) or vigabatrin (first-line if tuberous sclerosis is the etiology), and early treatment improves developmental outcomes. The prognosis is guarded, with many patients progressing to Lennox-Gastaut syndrome.
Lennox-Gastaut Syndrome
Lennox-Gastaut syndrome has onset between 1 and 8 years (peak 3-5 years) and involves multiple seizure types including tonic seizures (especially during sleep), atonic seizures (drop attacks), atypical absences, myoclonic seizures, and generalized tonic-clonic seizures. The EEG shows slow (less than 2.5 Hz) spike-and-wave complexes and generalized paroxysmal fast activity during sleep. Cognitive impairment is usually progressive. Treatment options include valproic acid, clobazam, rufinamide, lamotrigine, and cannabidiol (Epidiolex), with carbamazepine and phenytoin avoided as they worsen seizures. Vagus nerve stimulation and corpus callosotomy may be considered for drop attacks. The prognosis involves drug-resistant epilepsy in most patients with lifelong seizures and intellectual disability.
Dravet Syndrome
Dravet syndrome has onset in the first year of life, typically at 5-8 months. Initial seizures are prolonged febrile and afebrile hemiclonic or generalized seizures, often triggered by fever or warm baths. Later, multiple seizure types emerge including myoclonic, atypical absence, and focal seizures, along with developmental stagnation and regression. SCN1A pathogenic variants (loss-of-function) are identified in more than 80% of cases. EEG may be initially normal but later shows generalized and multifocal epileptiform discharges. Treatment includes valproic acid, clobazam, stiripentol, cannabidiol, and fenfluramine. Sodium channel blockers (carbamazepine, oxcarbazepine, phenytoin, lamotrigine) are strictly contraindicated as they worsen seizures. There is a high risk of SUDEP, and cognitive and behavioral comorbidities are significant.
Genetic Considerations
Genetic testing including epilepsy gene panels, chromosomal microarray, and whole exome sequencing is increasingly important in childhood epilepsy. Identification of a specific genetic etiology can guide treatment, such as vigabatrin for TSC-related epilepsy or avoiding sodium channel blockers in Dravet syndrome. Precision medicine examples include mTOR inhibitors (everolimus) for TSC-related epilepsy and quinidine for KCNT1-related epilepsy (with variable response). Genetic counseling should be offered to families with identified pathogenic variants.
Clinical Pearls
Simple febrile seizures do not require antiseizure medication, EEG, or neuroimaging; parental education and reassurance are the cornerstones of management. In childhood absence epilepsy, ethosuximide is first-line when absence seizures are the only seizure type, and sodium channel blockers worsen absence seizures. Dravet syndrome is a clinical and genetic diagnosis; SCN1A testing should be performed in any infant with prolonged febrile seizures beginning in the first year of life, especially if followed by afebrile seizures. Sodium channel blockers are contraindicated in Dravet syndrome and can precipitate status epilepticus. Infantile spasms require urgent treatment with ACTH or vigabatrin, and early treatment within 1 month of spasm onset is associated with better developmental outcomes.
References
- Scheffer IE, Berkovic S, Capovilla G, et al. ILAE classification of the epilepsies: position paper of the ILAE Commission for Classification and Terminology. Epilepsia. 2017;58(4):512-521.
- Subcommittee on Febrile Seizures, American Academy of Pediatrics. Neurodiagnostic evaluation of the child with a simple febrile seizure. Pediatrics. 2011;127(2):389-394.
- Wirrell EC, Nabbout R, Scheffer IE, et al. Methodology for classification and definition of epilepsy syndromes with a list of syndromes: report of the ILAE Task Force on Nosology and Definitions. Epilepsia. 2022;63(6):1333-1348.
- Dravet C, Oguni H. Dravet syndrome (severe myoclonic epilepsy in infancy). Handb Clin Neurol. 2013;111:627-633.