Absence seizure

What it is

Epilepsy is defined as 2 unprovoked seizures 24 h apart; it is a chronic neurological disorder characterised by recurrent unprovoked seizures, consisting of transient signs or symptoms associated with abnormal, excessive or synchronous neuronal activity in the brain.

Seizures divide first into generalised, where the discharge arises from both hemispheres, and focal, where they arise from one hemisphere or part of one. The generalised ones are absence, myoclonic, tonic, tonic-clonic and atonic. Within the generalised group the absence seizure is the nonconvulsive one, while the tonic, myoclonic, clonic and tonic-clonic are the convulsive ones.

Childhood absence epilepsy is the disorder these seizures sit in.

How it presents

Onset is at 6-7 years, and the disorder, also named pyknolepsy, is less common in males than in females.

• Absence seizures lasting 5-10 seconds, up to 100x a day.
• Brief unresponsiveness without convulsions.
• Amnestic during the seizures; children appear to be staring or daydreaming.
• Lip smacking, eye fluttering or head nodding are common.
• No postictal phase.

Triggers are hyperventilation and lights.

The atypical absence seizure is set apart by a more gradual onset and ending and a duration of more than 30 seconds.