Prevalence
~5% to 10% of children with seizures.

Incidence
~2.8/10,000 live births.


Editor's note: This section was sponsored by the generosity of Lundbeck. However, in order to avoid any possible sponsorship bias, the sponsor was not known to either the author or the editor.

Epilepsy Therapy Project would like to thank Lundbeck for their generosity in providing an unrestricted educational grant in support of the Lennox-Gastaut Syndrome section on professionals.epilepsy.com.

Age at onset
~1 to 7 years; peak at 3 to 5 years.

Sex
Males (60%) slightly predominate.

Neurological and mental state
Motor, cognitive, and behavioral abnormalities in ~60% prior to seizure onset.

Etiology
Extensive and diverse. Often severe brain disorders and malformations of cortical development (70%). 1/3 are idiopathic or probably symptomatic cases.

Clinical manifestations
Clusters of multiform seizures and mental retardation. Tonic seizures, atonic seizures, and atypical absences in this order of prevalence are the characteristic seizures. Falls, often traumatic, are common.

Non-convulsive status epilepticus of atypical absences, tonic and atonic seizures, and myoclonic jerks occur in half of the patients.

Seizure-precipitating factors
Sleep and inactivity.

Timing
Tonic seizures mainly during sleep.

Diagnostic procedures
Biochemical, hematological, metabolic, and other relevant screenings are rarely abnormal, depending on cause. Brain imaging is often abnormal.

Inter-ictal EEG
Background is usually slow, with paroxysms of fast rhythms and <2.5 Hz spike waves.

Ictal EEG
Variable according to seizure type. Tonic seizures = accelerating fast paroxysms (~20 Hz), atypical absences = <2.5 Hz spike-slow waves, myoclonic seizures = polyspikes, atonic seizures = spikes/polyspikes/slow spike waves and fast paroxysms. Flattening of all EEG activity alone or in combination with fast paroxysms is common.

Prognosis
Poor; 5% die, 80% to 90% continue having seizures in adult life. Nearly all (85% to 92%) have severe neurological and mental deficits. Normal development is exceptional.

Differential diagnosis
Non-epileptic conditions, other epileptic encephalopathies, EM-AS.

Management options*

Complete seizure control is highly unlikely. Valproate (all seizures), clonazepam (myoclonic), and phenytoin (tonic) are used. Clobazam and rufinamide are particularly helpful for atonic and tonic seizures. Lamotrigine, levetiracetam, or topiramate may be more effective than older medications. Felbamate is for specific cases.

Steroids are occasionally helpful.

Ketogenic diet is an appropriate option.

Vagal nerve stimulation may be useful but in limited cases.

Resective neurosurgery for intractable cases with localized structural lesions can be considered.

Corpus callosotomy for intractable drop attacks can be considered.

In status epilepticus, intravenous benzodiazepines are used, sometimes with concomitant steroids, and with respiratory assistance. Intravenous diazepam and lorazepam may induce tonic seizures.

A multidisciplinary approach to the management of the patient and support for the family is needed.

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

Authored by: C. P. Panayiotopoulos MD PhD FRCP on 1/2005
Reviewed by: Steven C. Schachter MD on 6/2008
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