Generalized epilepsy in childhood

Last updated: May 30, 2021

Summary

Pediatric generalized epilepsy syndromes are a diverse group of conditions with onset in infancy or childhood. The International League Against Epilepsy (ILAE) classifies generalized epilepsy syndromes according to the etiology as either idiopathic, symptomatic, or cryptogenic. In idiopathic generalized epilepsy syndromes, the most common form of childhood epilepsy, genetic causes are suspected. The symptomatic forms are associated with metabolic or structural abnormalities, while the etiology of cryptogenic epilepsies is unknown. The syndromes are further classified according to the patient's age at onset, as well as clinical and EEG characteristics. A detailed patient history, including a description of seizures, offers vital diagnostic clues. The diagnosis may be confirmed with an EEG. With adequate treatment, idiopathic epilepsy syndromes have a good prognosis. In comparison, symptomatic epilepsy syndromes do not respond well to treatment and have a relatively poor prognosis, often resulting in developmental delays and cognitive impairments.

Etiology

Etiology of seizures according to age

Infants
- Congenital (idiopathic; genetic association)
- Secondary to
  - Perinatal or postnatal infections
  - Head trauma
  - Metabolic disorders
Children
- Idiopathic (genetic association suspected)
- Secondary to
  - Metabolic disorders
  - Structural abnormalities of the cerebrum
  - Infections
  - Head trauma
  - Febrile seizures

References:^[1]^[2]^[3]^[4]

Idiopathic generalized epilepsy syndromes

Idiopathic generalized epilepsy syndromes are the most common forms of epilepsy in children. Genetic causes are suspected and, in some cases, have been identified. The majority of these syndromes occur in otherwise healthy individuals.

	Age at disease onset	Clinical findings and characteristics	Ictal EEG	Treatment	Prognosis
Childhood absence epilepsy (pyknolepsy)	6–7 years Sex: ♂ < ♀	Absence seizures lasting 5–10 seconds up to 100x/day Brief unresponsiveness without convulsions Amnestic during seizures; children appear to be staring or daydreaming Lip smacking, eye fluttering or head nodding are common No postictal phase Atypical absence seizure: more gradual onset and ending, duration of > 30 seconds. Triggers: hyperventilation, lights	3 Hz spikes and waves in all regions of the brain	1^st line: ethosuximide 2^nd line: sodium valproate 3^rd line: lamotrigine	80% of children are seizure-free with treatment Usually subsides before adulthood
Juvenile absence epilepsy	9–13 years Sex: ♂ = ♀	Absence seizures Tonic-clonic seizures (on awakening) are common Photosensitivity less common	Regular 3–4 Hz spikes and waves in all regions of the brain	1^st-line: valproic acid Avoid triggers: sleep deprivation, alcohol, drugs, flickering lights	60% are seizure-free under treatment Transition to juvenile myoclonic epilepsy possible
Juvenile myoclonic epilepsy (Janz syndrome)	12–20 years	Triad of seizures : Bilateral symmetrical myoclonic jerks, primarily after awakening, without impaired consciousness Generalized tonic-clonic seizures Absence seizures with impaired consciousness Triggers: sleep deprivation, alcohol consumption, flickering lights	Irregular 3–5 Hz polyspikes and waves with frontocentral predominance	Responds well to antiseizure drug therapy; seizures become less frequent in adulthood Life-long treatment usually required (high risk of recurrence) Increased risk of psychiatric comorbidities

Age at disease onset

Clinical findings and characteristics

Ictal EEG

Treatment

Prognosis

Childhood absence epilepsy

(pyknolepsy)

6–7 years
Sex: ♂ < ♀

Absence seizures lasting 5–10 seconds up to 100x/day
- Brief unresponsiveness without convulsions
- Amnestic during seizures; children appear to be staring or daydreaming
- Lip smacking, eye fluttering or head nodding are common
- No postictal phase
Atypical absence seizure: more gradual onset and ending, duration of > 30 seconds.
Triggers: hyperventilation, lights

3 Hz spikes and waves in all regions of the brain

1^st line: ethosuximide
2^nd line: sodium valproate
3^rd line: lamotrigine

80% of children are seizure-free with treatment
Usually subsides before adulthood

Juvenile absence epilepsy

9–13 years
Sex: ♂ = ♀

Absence seizures
Tonic-clonic seizures (on awakening) are common
Photosensitivity less common

Regular 3–4 Hz spikes and waves in all regions of the brain

1^st-line: valproic acid
Avoid triggers: sleep deprivation, alcohol, drugs, flickering lights

60% are seizure-free under treatment
Transition to juvenile myoclonic epilepsy possible

Juvenile myoclonic epilepsy

(Janz syndrome)

12–20 years

Triad of seizures :
- Bilateral symmetrical myoclonic jerks, primarily after awakening, without impaired consciousness
- Generalized tonic-clonic seizures
- Absence seizures with impaired consciousness
- Triggers: sleep deprivation, alcohol consumption, flickering lights

Irregular 3–5 Hz polyspikes and waves with frontocentral predominance

Responds well to antiseizure drug therapy; seizures become less frequent in adulthood
Life-long treatment usually required (high risk of recurrence)
Increased risk of psychiatric comorbidities

References:^[1]^[5]^[6]^[7]^[8]^[9]^[10]^[11]^[12]

Symptomatic or cryptogenic generalized epilepsy syndromes

Symptomatic generalized epilepsy syndromes typically occur in association with structural or metabolic abnormalities, whereas cryptogenic generalized epilepsy syndromes describe seizures of unknown etiology. These syndromes do not respond well to antiseizure drug therapy and are commonly associated with developmental delays, as well as motor and cognitive impairments.

	Age at disease onset	Etiology	Clinical findings and characteristics	EEG	Treatment	Prognosis
Infantile spasms (West syndrome)	3–7 months Sex: ♂ > ♀	Perinatal infections Hypoxic-ischemic injury PKU Tuberous sclerosis complex Idiopathic	Sudden symmetric, synchronous spasms, usually in clusters of 5–10 Jerking flexion (jackknife movement) or extension of the neck, torso, and extremities Followed by a tonic phase	Hypsarrhythmia: characteristic finding in interictal EEG; high-voltage delta waves with irregular multifocal spikes and slow waves Ictal EEG: very heterogeneous	First-line treatment: ACTH, prednisone, or vigabatrin	Poor; increased mortality Neurodevelopmental delay, regression of psychomotor abilities in > 85% of cases In ∼ 50% of cases spasms cease before age 5 years Most cases develop other forms of epilepsy )
Lennox-Gastaut syndrome	3–5 years Sex: ♂ > ♀	Majority of cases due to structural brain abnormalities 40% of cases are cryptogenic	Multiple types of seizures: myoclonic, tonic, atonic, absences Developmental delays Frequently periods of status epilepticus	Multifocal sharp and slow waves Abnormal interictal EEG: slow spike-wave pattern	Attempt anticonvulsive treatment, e.g., valproic acid, clobazam, lamotrigine, felbamate ^[13] Ketogenic diet, vagus nerve stimulation, surgery (see therapy of epilepsy)	Poor; only 10% are seizure-free under treatment Developmental delay, cognitive impairment, and psychotic symptoms Mortality rate of 3–7%

Age at disease onset

Etiology

Clinical findings and characteristics

EEG

Treatment

Prognosis

Infantile spasms

(West syndrome)

3–7 months
Sex: ♂ > ♀

Sudden symmetric, synchronous spasms, usually in clusters of 5–10
Jerking flexion (jackknife movement) or extension of the neck, torso, and extremities
Followed by a tonic phase

Hypsarrhythmia: characteristic finding in interictal EEG; high-voltage delta waves with irregular multifocal spikes and slow waves
Ictal EEG: very heterogeneous

First-line treatment: ACTH, prednisone, or vigabatrin

Poor; increased mortality
Neurodevelopmental delay, regression of psychomotor abilities in > 85% of cases
In ∼ 50% of cases spasms cease before age 5 years
Most cases develop other forms of epilepsy )

Lennox-Gastaut syndrome

3–5 years
Sex: ♂ > ♀

Majority of cases due to structural brain abnormalities
40% of cases are cryptogenic

Multiple types of seizures: myoclonic, tonic, atonic, absences
Developmental delays
Frequently periods of status epilepticus

Multifocal sharp and slow waves
Abnormal interictal EEG: slow spike-wave pattern

Attempt anticonvulsive treatment, e.g., valproic acid, clobazam, lamotrigine, felbamate ^[13]
Ketogenic diet, vagus nerve stimulation, surgery (see therapy of epilepsy)

Poor; only 10% are seizure-free under treatment
Developmental delay, cognitive impairment, and psychotic symptoms
Mortality rate of 3–7%

References:^[1]^[2]^[9]^[11]^[12]^[13]^[14]^[15]^[16]^[17]^[18]

Diagnosis

Seizure history (see diagnosis of epilepsy)
EEG: abnormal electrical discharges
Laboratory analysis
- Rule out metabolic abnormalities (e.g., hypoglycemia, electrolyte abnormalities)
- Toxicology screening; determine anticonvulsant plasma levels in previously diagnosed patients receiving medical treatment
- Blood cultures and lumbar puncture in febrile patients
Cranial MRI and CT scan: rule out structural brain abnormalities (e.g., tumors)

References:^[19]

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