Lennox-Gastaut Syndrome

Medically Reviewed by Christopher Melinosky, MD on December 21, 2022
6 min read

Lennox-Gastaut syndrome (LGS) is a rare and severe kind of epilepsy that starts in childhood. Children with LGS have seizures often, and they have several different kinds of seizures.

This condition is hard to treat, but researchers are looking for new therapies. Finding practical and emotional support is key to help you give your child the best quality of life while facing the challenges and stress this illness brings.

The seizures usually start between ages 2 and 6. Children with LGS have learning difficulties and developmental delays (like sitting, crawling, walking) that can be moderate to severe. They can also have behavioral problems.

Each child develops differently, and it's impossible to predict how a child with LGS will do. While most children have ongoing seizures and some form of learning disability, some may respond well to treatment and have fewer seizures.

Others may continue to have seizures often, as well as problems with thinking, development, and behavior, and will need help with daily living activities. Some parents find that a special diet, called the ketogenic diet, helps.

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 encephalitis, meningitis, or rubella)
  • Seizures that start in infancy, called infantile spasms or West’s syndrome
  • A 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
  • Genetics

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.

Your doctor will want to know:

  • When did you first notice a problem?
  • Has your child had seizures? How many? How frequent?
  • How long did it last, and how would you describe what happened?
  • Does your child have any medical conditions or take any medications?
  • Were there any complications during birth?
  • Do you know if your child has any brain injuries?
  • Does your child have problems with learning or behavior?

Your doctor will look for three signs to diagnose LGS:

  • Multiple kinds of seizures that are hard to control
  • Developmental delays or intellectual disability
  • An electroencephalogram (EEG) that shows a specific kind of pattern, called a slow spike-wave pattern, between seizures. An EEG uses a machine to record electrical activity in the brain.
  • Does my child need any more tests?
  • Have you treated other children with this condition?
  • What treatment do you recommend?
  • How will treatment make my child feel?
  • What can I do to keep my child safe during seizures?
  • Are there clinical trials my child could take part in?
  • How do I connect with other families who have children with LGS?


Doctors may prescribe a variety of drugs to treat seizures from LGS. The goal is to reduce the number of seizures with medication that causes the fewest side effects. Finding the right treatment for your child will probably take time and close coordination with the doctor. Drugs used to treat seizures include:

Usually, no single medication controls seizures completely. The doctor will monitor your child's medication closely, especially if your child takes more than one at a time.


A special high-fat, low-carbohydrate diet, called the ketogenic diet, helps some people with epilepsy, including some children with LGS. It's a high-fat, low-protein, low-carb diet. It has to be started in a specific way and followed very strictly, so you need a doctor's supervision.

Your doctor will watch closely to see whether or when any medication levels can be lowered. Because the diet is so specific, your child may need to take vitamin or mineral supplements.

Doctors aren't sure why the ketogenic diet works, but some studies show that children with epilepsy who stay on the diet have a better chance of reducing their seizures or their medications.

For some kids, a modified Atkins diet may work, too. It is slightly different from the ketogenic diet. You don't have to restrict calories, protein, or fluids. Also, you don't weigh or measure foods. Instead, you monitor carbohydrates.

People with seizures that are hard to treat have also tried a low glycemic index diet. This diet focuses on the type of carbs, as well as the amount, that someone eats.

Medical Marijuana

A lot of attention has been focused on using medical marijuana to treat children with epilepsy, and many families are interested in learning more. Doctors haven't yet studied the use of medical marijuana in children who have LGS, and most of the studies using it to treat epilepsy have focused on short-term benefits. According to the Lennox-Gastaut Foundation, more research is needed to find out if this is a safe and effective treatment for children with LGS.


If medications and other treatments aren't reducing the number of seizures, your doctor may suggest surgery.

The vagus nerve stimulator is a small device placed in the arm or near the chest. It sends electrical impulses to the vagus nerve, which runs from the abdomen to the brain. The nerve then sends those impulses to the brain to help control seizures. The surgery is done under general anesthesia and takes about an hour.

The RNS stimulator is a device that's placed inside the skull and is connected to the brain. It senses any abnormal electrical activity and then sends electrical impulses to the brain to try to keep seizures from happening.

Corpus callosotomy divides the left and right hemispheres of the brain. That keeps seizures that start in one part of the brain from spreading to the opposite side. It is usually suggested only for people who have severe, uncontrollable seizures that cause them to fall and get hurt. Someone who has corpus callosotomy will need to stay in the hospital for 2 to 4 days, and will keep taking anti-seizure drugs after they go home.

Parenting a child with LGS is tough. If your child has frequent seizures, they may need to wear a helmet to protect them if they fall. 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.

To learn more about Lennox-Gastaut syndrome, you can visit the web site of the LGS Foundation. It’s a good starting place to find the support you and your family may need.