The EEG finding of 3 Hz spike-and-wave discharges in a child who briefly stares blankly and stops activity for ~10 seconds is pathognomonic of:

• A Lennox-Gastaut syndrome
• B Childhood absence epilepsy ✓
• C Juvenile myoclonic epilepsy
• D West syndrome (infantile spasms)

Explanation

Childhood absence epilepsy features brief staring spells (absences) with abrupt onset and offset, and the pathognomonic EEG of bilateral symmetric 3 Hz spike-and-wave complexes arising from a normal background. The thalamocortical circuit (through thalamic pacemaker neurons) generates these discharges. Lennox-Gastaut shows slow (<2.5 Hz) spike-wave with multiple seizure types; West syndrome shows hypsarrhythmia; juvenile myoclonic epilepsy shows 4–6 Hz polyspike-wave.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

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Written and medically reviewed by the StethoPrep medical team.