Absence Seizure

Overview

Absence seizures are a type of generalized non-motor (petit mal) seizure characterized by sudden, brief lapses of consciousness (staring spells), lasting 5–20 seconds, often with subtle automatisms (eye blinking, lip smacking). They usually occur in children and may happen multiple times per day.

EEG typically shows 3-Hz generalized spike-and-wave discharges. Unlike focal seizures, absence seizures have abrupt onset and termination without postictal confusion.

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Treatment Options

1. First-Line Therapy

• Ethosuximide (drug of choice in typical absence seizures)

  • Dose:

    • Children: Start 10–15 mg/kg/day PO in 2 divided doses; increase by 5 mg/kg every 4–7 days.

    • Usual: 20–30 mg/kg/day; max 40 mg/kg/day (≤1500 mg/day).

  • Side effects: GI upset, lethargy, headache, rare blood dyscrasias.

• Valproic acid (sodium valproate)

  • Preferred if absence + generalized tonic–clonic seizures coexist.

  • Dose:

    • Start 10–15 mg/kg/day PO, increase by 5–10 mg/kg weekly.

    • Usual: 20–60 mg/kg/day in divided doses.

  • Side effects: weight gain, tremor, hepatotoxicity, teratogenicity.

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2. Alternative Therapy

• Lamotrigine

  • Dose:

    • Start 0.3–0.6 mg/kg/day PO; titrate slowly to 5–15 mg/kg/day in 1–2 divided doses (max 200–400 mg/day).

  • Less effective than ethosuximide or valproate but used when those are contraindicated.

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3. Drugs to Avoid

• Carbamazepine, phenytoin, gabapentin, vigabatrin → may worsen absence seizures.

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Supportive Care

• Seizure safety counseling: avoid swimming alone, caution with driving (depending on local laws).

• Educational support: absence seizures may cause academic difficulties due to frequent lapses in attention.

• Monitoring: periodic EEGs and drug level checks.

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Key Notes

• Ethosuximide is first choice for isolated absence seizures.

• Valproate is best if other generalized seizures are present.

• Most children outgrow absence seizures by adolescence, but some progress to juvenile absence epilepsy or generalized tonic–clonic seizures.

• Early treatment improves quality of life and reduces academic impairment.