Skip to
  1. Homepage
  2. Rare diseases
  3. Search
Simple search

Simple search

(*) mandatory field


Other search option(s)

Lennox-Gastaut syndrome

Synonym(s) -
Prevalence 1-5 / 10 000
Inheritance Autosomal dominant
or Multigenic/multifactorial
or Not applicable
Age of onset Childhood
  • G40.4
  • C0238111
  • C535500
  • 10048816


Disease definition

Lennox-Gastaut syndrome (LGS) belongs to the group of severe childhood epileptic encephalopathies.


Incidence is estimated at 1:1,000,000 inhabitants per year, and the estimated prevalence is 15/100,000. LGS represents 5-10% of epileptic patients, and 1-2% of all childhood epilepsies.

Clinical description

This disorder is defined as a cryptogenic or symptomatic generalized epilepsy, which is characterized by the following symptomatic triad: several epileptic seizures (atypical absences, axial tonic seizures and sudden atonic or myoclonic falls); diffuse slow interictal spike wave in the waking electroencephalogram (EEG) (< 3 Hz) and fast rhythmic bursts (10 Hz) during sleep; slow mental development associated with personality disturbances. The onset occurs between 2 and 7 years. The most characteristic clinical manifestations in LGS consist of tonic seizures (17-92%), atonic seizures (26-56%) and atypical absences (20-65%).


The symptoms in cryptogenic LGS forms (20-30%) appear without antecedent history or evidence of brain pathology, whereas symptomatic LGS cases (30-75%) are associated with pre-existent brain damage. In the cryptogenic form, symptoms appear without antecedent history or evidence of cerebral pathology. The symptomatic cases are associated with perinatal asphyxia, tuberous sclerosis, meningoencephalitis sequelae, cortical dysplasia, cranial trauma and more rarely tumors or metabolic diseases. Some idiopathic cases have been described (< 5%).

Diagnostic methods

Diagnosis is based on the presence of specific EEG recordings.

Differential diagnosis

All the epilepsies with frequent and brief seizures (``minor motor seizures''), occurring in childhood should be considered with myoclonic epilepsies, benign atypical partial epilepsy of childhood, epilepsy absence with tonic or atonic component, ESES syndrome, Landau-Kleffener syndrome, multifocal severe epilepsy, Rett syndrome, Angelman syndrome, and ceroid lipofuscinoses (see these terms) being included in the differential diagnosis.

Management and treatment

Treatment is problematic as LGS isusually refractory to conventional therapy. Some of the new antiepileptic drugs (AED; felbamate, lamotrigine, topiramate and levetiracetam) have proven to be efficient in the control of seizures in LGS. The drug rufinamide received a European marketing authorization in January 2007. LGS is one of the most severe epileptic syndromes in childhood, it is generally refractory to treatment and intellectual deficit is frequently associated with the condition.


The mortality rate is around 5% but is only rarely directly related to the epilepsy itself. Death is usually associated with accidents or episodes of status epilepticus.

Expert reviewer(s)


(*) Required fields.

Attention: Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.

Captcha image

Detailed information

Summary information
Emergency guidelines
Clinical genetics review
Get Acrobat Reader
The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.