Brief Seizures: Absence Seizures and Sub-Second Events

Seizures can last <1 second. Absence seizures (typical) last 3–20 seconds: abrupt impairment of consciousness, staring, eyelid fluttering, no postictal state. Myoclonic jerks are <100 ms. Epileptic spasms (infantile spasms) last 0.5–2 seconds. Ultra-brief events (<1 sec) may be myoclonus or focal aware seizures with minimal manifestation.

EEG correlates: 3 Hz spike-wave (absence), polyspike-wave (myoclonic), hypsarrhythmia (spasms). Diagnosis requires clinical correlation and EEG. Absence seizures are common in childhood absence epilepsy (age 4–10), often remit by adolescence.