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Generalized epilepsy in childhood

Last updated: May 30, 2021

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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 of seizures according to age

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

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)

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

Juvenile absence epilepsy

  • Regular 3–4 Hz spikes and waves in all regions of the brain
  • 1st-line: valproic acid
  • Avoid triggers: sleep deprivation, alcohol, drugs, flickering lights

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 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)

  • 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
  • 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
  • Majority of cases due to structural brain abnormalities
  • 40% of cases are cryptogenic
  • Multifocal sharp and slow waves
  • Abnormal interictal EEG: slow spike-wave pattern

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

References:[19]

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