Summary

• Typical absence seizure: behavioural arrest or staring, lasting 5 to 10 seconds, interrupting otherwise normal activity. Can be hyperventilation-induced.
• Atypical absence seizures: less distinct beginning and end, not usually precipitated by hyperventilation.
• EEG is the definitive test. Determining the exact nature of their seizures is the key to the appropriate treatment and prognosis.
• Most typical absence seizures are medically responsive, and childhood absence epilepsy (CAE) tends to remit by adulthood. Typical absence seizures in CAE, juvenile absence epilepsy (JAE), and juvenile myoclonic epilepsy (JME) are treated with ethosuximide, valproate, or lamotrigine as first-line therapies.
• Atypical absence seizures tend to be medically refractory and associated with mental retardation. Atypical absence seizures in Lennox-Gastaut syndrome and epilepsy with myoclonic absences are treated with valproate or lamotrigine as first-line therapies.