~1% to 2% of epilepsies that start before the age of 3 years.

Age at onset
6 months to 3 years but also earlier (4 months) or later (4 years).

Males (66%) predominate.

Neurological and mental state

Probably genetic. It is the earliest form of idiopathic generalized epilepsy (IGE).

Clinical manifestations
Myoclonic jerks, singular or clusters. Consciousness is intact but mild clouding may occur during cluster of jerks.

There are no other types of seizures other than simple febrile seizures in 10%.

Seizure-precipitating factors
Photosensitivity (20%), unexpected acoustic or tactile stimuli (10%).

Awakening or during the first hours of sleep.

Inter-ictal EEG

Ictal EEG
Generalized polyspike or spike and slow-wave discharges.

Remission usually occurs within 1 year (6 months to 5 years) from onset. 10% to 20% develop infrequent generalized tonic-clonic seizures in their early teens. 10% to 20%, if untreated, may develop mild cognitive, behavioral, or motor deficits. EEG photosensitivity may persist after remission of seizures.

Differential diagnosis
(1) Non-epileptic conditions (hypnagogic jerks and benign non-epileptic myoclonus) and (2) Dravet syndrome and West syndrome.

Management options*
Excellent response to valproate, which should be withdrawn 3 to 5 years from onset. Patients with acoustic and somatosensory evoked myoclonus may not need treatment.

*Expert opinion, please check FDA-approved indications and prescribing information

This section 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. The Educational Kit on Epilepsies was produced through an unrestricted educational grant from UCB Pharma SA. UCB Pharma SA assumes no responsibility of the views expressed and recommended treatments in these volumes.

Authored By: 
C. P. Panayiotopoulos MD, PhD, FRCP
Authored Date: 
Reviewed By: 
Steven C. Schachter MD
Sunday, June 1, 2008