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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

Lennox-Gastaut syndrome

Reviewed July 2010

What is Lennox-Gastaut syndrome?

Lennox-Gastaut syndrome is a form of severe epilepsy that begins in childhood. It is characterized by multiple types of seizures and intellectual disability.

People with Lennox-Gastaut syndrome begin having frequent seizures in early childhood, usually between ages 3 and 5. More than three-quarters of affected individuals have tonic seizures, which cause the muscles to stiffen (contract) uncontrollably. These seizures occur most often during sleep. Also common are atypical absence seizures, which cause a partial or complete loss of consciousness. Additionally, many affected individuals have drop attacks, which are sudden episodes of weak muscle tone. Drop attacks can result in falls that cause serious or life-threatening injuries. Other types of seizures have been reported less frequently in people with Lennox-Gastaut syndrome.

Most of the seizures associated with Lennox-Gastaut syndrome are very brief. However, more than two-thirds of affected individuals experience at least one prolonged period of seizure activity known as nonconvulsive status epilepticus. These episodes can cause confusion and a loss of alertness lasting from hours to weeks.

Almost all children with Lennox-Gastaut syndrome develop learning problems and intellectual disability associated with their frequent seizures. Because the seizures associated with this condition are difficult to control with medication, the intellectual disability tends to worsen with time. Some affected children develop additional neurological abnormalities and behavioral problems. Many also have delayed development of motor skills such as sitting and crawling. As a result of their seizures and progressive intellectual disability, most people with Lennox-Gastaut syndrome require help with some or all of the usual activities of daily living. However, a small percentage of affected adults live independently.

People with Lennox-Gastaut syndrome have an increased risk of death compared to their peers of the same age. Although the increased risk is not fully understood, it is partly due to poorly controlled seizures and injuries from falls.

How common is Lennox-Gastaut syndrome?

Lennox-Gastaut syndrome affects an estimated 1 in 50,000 to 1 in 100,000 children. This condition accounts for about 4 percent of all cases of childhood epilepsy. For unknown reasons, it appears to be more common in males than in females.

What genes are related to Lennox-Gastaut syndrome?

Researchers have not identified any genes specific to Lennox-Gastaut syndrome, although the disorder likely has a genetic component. About two-thirds of cases are described as symptomatic, which means that they are related to an existing neurological problem. Symptomatic Lennox-Gastaut syndrome can be associated with brain injuries that occur before or during birth, problems with blood flow in the developing brain, brain infections, or other disorders affecting the nervous system. The condition can also result from a brain malformation known as cortical dysplasia or occur as part of a genetic disorder called tuberous sclerosis complex. Many people with Lennox-Gastaut syndrome have a history of recurrent seizures beginning in infancy (infantile spasms) or a related condition called West syndrome.

In about one-third of cases, the cause of Lennox-Gastaut syndrome is unknown. When the disorder occurs without an apparent underlying reason, it is described as cryptogenic. Individuals with cryptogenic Lennox-Gastaut syndrome have no history of epilepsy, neurological problems, or delayed development prior to the onset of the disorder.

How do people inherit Lennox-Gastaut syndrome?

Most cases of Lennox-Gastaut syndrome are sporadic, which means they occur in people with no history of the disorder in their family. However, 3 to 30 percent of people with this condition have a family history of some type of epilepsy. People with the cryptogenic form of Lennox-Gastaut syndrome are more likely than people with the symptomatic form to have a family history of epilepsy.

Where can I find information about diagnosis or management of Lennox-Gastaut syndrome?

These resources address the diagnosis or management of Lennox-Gastaut syndrome and may include treatment providers.

  • Cleveland Clinic (
  • Genetic Testing Registry: Epileptic encephalopathy Lennox-Gastaut type (
  • National Institute of Neurological Disorders and Stroke: Diagnosis and Treatment of Epilepsy (
  • News Release: FDA Approves New Drug to Treat Severe Form of Epilepsy (U.S. Food and Drug Administration, November 20, 2008) (

You might also find information on the diagnosis or management of Lennox-Gastaut syndrome in Educational resources and Patient support.

General information about the diagnosis ( and management ( of genetic conditions is available in the Handbook. Read more about genetic testing (, particularly the difference between clinical tests and research tests (

To locate a healthcare provider, see How can I find a genetics professional in my area? ( in the Handbook.

Where can I find additional information about Lennox-Gastaut syndrome?

You may find the following resources about Lennox-Gastaut syndrome helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for Lennox-Gastaut syndrome?

  • childhood epileptic encephalopathy with diffuse slow spikes and waves
  • LGS

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines ( and How are genetic conditions and genes named? ( in the Handbook.

What if I still have specific questions about Lennox-Gastaut syndrome?

Ask the Genetic and Rare Diseases Information Center (

What glossary definitions help with understanding Lennox-Gastaut syndrome?

atypical ; cryptogenic ; disability ; dysplasia ; encephalopathy ; epilepsy ; epileptic ; family history ; malformation ; motor ; muscle tone ; nervous system ; neurological ; sclerosis ; seizure ; sporadic ; status epilepticus ; syndrome

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Arzimanoglou A, French J, Blume WT, Cross JH, Ernst JP, Feucht M, Genton P, Guerrini R, Kluger G, Pellock JM, Perucca E, Wheless JW. Lennox-Gastaut syndrome: a consensus approach on diagnosis, assessment, management, and trial methodology. Lancet Neurol. 2009 Jan;8(1):82-93. doi: 10.1016/S1474-4422(08)70292-8. Review. (
  • Autry AR, Trevathan E, Van Naarden Braun K, Yeargin-Allsopp M. Increased risk of death among children with Lennox-Gastaut syndrome and infantile spasms. J Child Neurol. 2010 Apr;25(4):441-7. doi: 10.1177/0883073809348355. Epub 2009 Dec 18. (
  • Crumrine PK. Lennox-Gastaut syndrome. J Child Neurol. 2002 Jan;17 Suppl 1:S70-5. Review. (
  • Hancock EC, Cross HH. Treatment of Lennox-Gastaut syndrome. Cochrane Database Syst Rev. 2009 Jul 8;(3):CD003277. doi: 10.1002/14651858.CD003277.pub2. Review. Update in: Cochrane Database Syst Rev. 2013;2:CD003277. (
  • Markand ON. Lennox-Gastaut syndrome (childhood epileptic encephalopathy). J Clin Neurophysiol. 2003 Nov-Dec;20(6):426-41. Review. (
  • Trevathan E, Murphy CC, Yeargin-Allsopp M. Prevalence and descriptive epidemiology of Lennox-Gastaut syndrome among Atlanta children. Epilepsia. 1997 Dec;38(12):1283-8. (
  • Trevathan E. Infantile spasms and Lennox-Gastaut syndrome. J Child Neurol. 2002 Feb;17 Suppl 2:2S9-2S22. Review. Erratum in: J Child Neurol. 2003 May;18(5):374. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: July 2010
Published: February 8, 2016