Lennox-Gastaut Syndrome (LGS)

Fact: Lennox-Gastaut Syndrome (LGS) accounts for only 2 to 5% of childhood epilepsies

What is ​Lennox-Gastaut Syndrome (LGS)?
Lennox-Gastaut Syndrome (LGS) is a rare and often debilitating form of childhood-onset epilepsy. The syndrome is characterized by a triad of signs including multiple seizure types, moderate to severe cognitive impairment, and an abnormal EEG with slow spike-wave complexes.  This triad of mixed seizures, abnormal EEG and intellectual impairment represents one of the most difficult forms of epilepsy to treat. LGS is also a physically dangerous epilepsy syndrome of childhood because of the frequent falls, injuries, and cognitive impairment that can severely limit quality of life.

LGS constitutes between 1-4% of pediatric epilepsies and typically appears between the second and sixth year of life. This translates to a prevalence of 14,500 - 18,500 children under the age of 18 in the United States and more than 30,000 children and adults in the U.S. 

Doctors don't always know what caused a child's LGS. In some cases, it could be caused by:

  • Lack of oxygen during birth
  • Severe brain injuries linked with pregnancy or birth, such as low birth weight or premature birth
  • Brain infections (such as encephalitismeningitis, or rubella)
  • Seizures that start in infancy, called infantile spasms or West’s syndrome
  • brain problem called cortical dysplasia, where some nerve fibers in the brain don’t line up right during development in the womb
  • Tuberous sclerosis, where non-cancerous tumors form in many places throughout the body, including the brain

Children with LGS have frequent and severe seizures. And they often have different kinds of seizures, including:

Atonic seizures. Also called "drop attacks," because the person loses muscle tone and can fall to the ground. Their muscles may jerk. These seizures are brief, usually lasting a few seconds.

Tonic seizures. These seizures cause the person's body to stiffen and can last for a few seconds to a minute. They usually happen when the person is asleep. If they happen when the person is awake, they can cause falls. Like atonic seizures, they are also called drop attacks.

Absence seizures. During these seizures, a person may have a blank stare or nod their head or blink quickly.

In some children, the first sign of LGS is an ongoing seizure that lasts 30 minutes, or continuous seizures without full recovery between them. This is called status epilepticus, and it is a medical emergency.

People with LGS may also have slower reaction time. Some have problems learning and processing information. They may have behavioral problems, too.

Lennox-Gastaut syndrome is defined as having a clinical triad that must be identified for a diagnosis. This triad consists of multiple seizures of different types, a distinctive brain wave pattern (slow [1.5- to 2.5-Hz] spike-and-wave pattern) and some degree of cognitive impairment and behavioral abnormalities. However, these symptoms may not all be present at the onset of the disorder, making an accurate diagnosis of Lennox-Gastaut syndrome difficult. The wide variety of potential causes of Lennox-Gastaut syndrome also complicates the diagnosis.

A diagnosis of Lennox-Gastaut syndrome is usually made based upon a thorough clinical evaluation, a detailed patient history and a complete physical and neurological evaluation including advanced imaging techniques, such as electroencephalography (EEG) and magnetic resonance imaging (MRI). During an EEG, the brain's electrical impulses are recorded. In individuals with LGS, such EEG testing typically reveals the distinctive brain wave pattern (slow [1.5- to 2.5-Hz] spike-and-wave pattern). During a MRI scan, three-dimensional images are produced that reflect the brain's anatomy; such scanning helps physicians examine brain structure and potentially locate the cause of the seizure activity

How do you treat LGS?
Treatment is difficult, because the seizures often don't respond to seizure medications or AEDs. The intellectual changes do not respond to any currently available medicine or treatment either.

Partial relief of seizures, and also falls and injuries from seizures, may be obtained by valproic acid, lamotrigine, topiramate, felbamate, clonazepam, rufinamide, clobazam and occasionally other medications. 

Rescue therapies, or treatments that can be given to help stop or shorten clusters or seizures is an important part of seizure care for people with LGS. 
Stimulation of the vagus nerve in the neck, with an implanted pacemaker (VNS Therapy) sometimes improves seizures in people with LGS.

Dietary therapies have also been very helpful in some people. 

An operation to separate the two halves of the brain, called corpus callosum surgery, may reduce seizures and injuries, but obviously is a big undertaking.  

What to Expect
Parenting a child with LGS is tough. If your child has frequent seizures, he may need to wear a helmet to protect him if he falls. You may have to deal with behavioral problems like acting out, and side effects from anti-seizure drugs.

There is no cure for LGS, although there is a lot of research to find treatments that work better.
Each child with LGS has different needs. Most continue to have seizures and intellectual disabilities after they grow up. Some may be able to live independently, but most will need help with daily activities. They may need to live in a group or assisted living home.

It's important for parents and siblings to get the support they need as caregivers and family members facing life with this severe condition. Talking with other families facing the same challenges can help you feel less isolated, and getting tips and information from others can make daily life easier.

Information on this page taken directly from:
​Epilepsy Foundation
National Organization for Rare Disorders

Want to learn more?

The following are organizations and/or websites dedicated to providing information and education surrounding Lennox-Gestaut Syndrome. These organizations are dedicated to research, education, awareness, and/or support. They are listed in Alphabetical order without any preference or prejudice. Listing these organizations is not a recommendation or referral in any regard for seeking treatment or consultation or support for treatment.

About Kids Health
Child Neurology Foundation
Epilepsy Foundation
LGS Foundation
National Institute for Neurological Disorders and Stroke
National Organization for Rare Disorders