Prevalence
~10% of childhood epilepsies.

Incidence
~7/100,000 of children with non-febrile seizures <16 years.

Age at onset
4 to 10 years; peak at 5 to 7 years.

Sex
2/3 are females.

Neurological and mental state
Normal.

Etiology
Genetically determined of unknown, probably multifactorial, mode of inheritance. Probable linkage with chromosomes 1p, 8q24, 5q31.1, and 19p13.2.

Clinical manifestations
Typical absence seizures in their most characteristic form. These are severe and frequent, tens or hundreds per day, hence the term pyknolepsy. They are of abrupt onset and abrupt termination, lasting from 4 to 20 sec (mainly ~10 sec). The hallmark of the absence is severe impairment of consciousness with unresponsiveness and interruption of the ongoing voluntary activity. Automatisms occur in 2/3 of the seizures but are not stereotyped. Mild myoclonic elements of eyes, eyebrows, and eyelids may feature at the onset of the absence. More severe and sustained myoclonic jerks of facial muscles indicate other IGEs.

Other than absences, types of seizures are incompatible with CAE except febrile seizures and solitary or infrequent generalized tonic-clonic seizures (usually in adolescence after absences have remitted).

Seizure-precipitating factors
Absences are nearly invariably provoked by hyperventilation.

Inter-ictal EEG
Normal background, with frequent rhythmic posterior delta activity.

Ictal EEG
Generalized 3 Hz (2.5 to 4 Hz) spike (single, double, or occasionally triple) slow-wave discharges.

Prognosis
Excellent, with remission of absences before the age of 12 years. Less than 10% of patients develop infrequent or solitary generalized tonic-clonic seizures in adolescence or adult life. Poor social adjustment has been reported.

Differential diagnosis
Non-epileptic episodic disorders or daydreaming. Hyperventilation for 3 min will provoke an absence in as many as 90% of those with CAE.

Other epilepsy syndromes with absence seizures that may be lifelong and have a worse prognosis should be meticulously differentiated from CAE.

Management options*
Monotherapy with valproate, ethosuximide, or lamotrigine. Adding small doses of lamotrigine to valproate may be the preferable combination in resistant cases.

Contraindicated drugs: vigabatrin#, tiagabine, carbamazepine, and gabapentin.

*Expert opinion, please check FDA-approved indications and prescribing information
#Not approved by the FDA

This page was adapted from:

The educational kit on epilepsies: The epileptic syndromes By C. P. Panayiotopoulos Originally published by MEDICINAE 21 Cave Street, Oxford OX4 1BA
First published 2006 and reprinted in 2007

Authored By: 
C. P. Panayiotopoulos MD, PhD, FRCP
I<
Authored Date: 
01/2006
Reviewed By: 
Steven C. Schachter MD
on: 
Sunday, June 1, 2008