An Overview of Lennox-Gastaut Syndrome

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Lennox-Gastaut syndrome (LGS) is an epilepsy syndrome that begins during childhood and is characterized by frequent—often daily—seizures that are difficult to control with medication. While you can live well into adulthood and older age with LGS, there is a moderately higher risk of death due to issues such as injury, seizures, medication side effects, and health problems such as infections.

Types of Seizures That Occur in Lennox-Gastaut Syndrome
Verywell / JR Bee


The symptoms of Lennox-Gastaut syndrome begin in early childhood, typically before the age of 4. Seizures are the most prominent symptom, and most children who have LGS may also develop cognitive dysfunction, delays in reaching developmental milestones, and behavior problems.

LGS continues into adulthood, but symptoms generally change with age.

Children with LGS often have many different types of seizures, while adults tend to have fewer types and less frequent seizures.


One of the hallmarks of Lennox-Gastaut syndrome is several types of seizures that occur frequently—as often as several times a day—which is more often than in most other types of epilepsy. 

Often, a person who has had a seizure may feel groggy and even unaware that a seizure occurred afterward.

A number of types of seizures occur with LGS.

Type of Seizures
Seizure Type Symptoms Loss of Consciousness? Duration
Tonic Sudden muscle rigidity; possible recurring relaxation and stiffening Usually A few seconds to a minute
Atonic Loss of muscle tone; possible falling Yes A few seconds
Myoclonic Brief spasms of arms and/or legs Rarely Several seconds
Atypical Absence Appearance of "spacing out," staring into space, lack of awareness Yes Less than 15 seconds
Tonic-clonic (less common) Involuntary jerking and stiffness; impaired recollection of the event Frequent One to two minutes
Status epilepticus Seizure requires emergency injection of medication to stop; possible brain damage or death (in LGS involving absence, tonic, or tonic-clonic seizures) Yes More than 30 minutes
Infantile spasms May precede diagnosis of LGS; sudden jerks in very young babies Possible Less than a second or two, often in a series

Developmental Delay

Children who have LGS also experience developmental delays, either cognitive (most common), physical, or both. The severity of this varies greatly from person to person.

Compromised physical abilities may interfere with independence.


There are several known causes of Lennox-Gastaut syndrome, including:

  • Disorders of brain development
  • Neurological conditions
  • Damage to the brain during fetal development or shortly after birth

However, sometimes no cause can be identified.

West Syndrome

An estimated 20% to 30% of children with LGS have West syndrome, a condition characterized by three features:

  • Infantile spasms
  • Developmental regression
  • A pattern of erratic brain activity on electroencephalogram (EEG), which is known as hypsarrhythmia

West syndrome has many causes, and children who have both LGS and West syndrome may need treatment for both conditions. West syndrome is often treated with adrenocorticotrophic hormone (ACTH) or steroids.

Tuberous Sclerosis

A disorder in which tumors grow in multiple areas of the body, tuberous sclerosis can cause Lennox-Gastaut syndrome and physical and/or cognitive deficits.


Hypoxia is oxygen deprivation. Children who experience hypoxia before or shortly after birth often have consequences related to brain development and function. This can manifest with a variety of problems, including LGS (with or without West syndrome) and cerebral palsy.


Encephalitis is an infection or inflammatory disease of the brain. It's likely to cause persistent problems, and Lennox-Gastaut syndrome can be one of them.

Cortical Dysplasia

A type of abnormal brain development that occurs before birth, cortical dysplasia is characterized by brain malformations and can cause LGS. Cortical dysplasia can be caused by genetic or hereditary problems, or by lack of oxygen or blood flow to the baby. In some cases, no reason is identified.


It can be emotionally difficult to find out that your child has Lennox-Gastaut syndrome. Most parents already have an idea that something serious is going on because of the repeated seizures and developmental problems. However, it's natural to still wish to hear that there is a minor cause behind it all.

If your child has symptoms of LGS, rest assured that his or her healthcare providers will test for all possibilities, including serious and minor diseases, and will not overlook important diagnostic tests or simple treatments for your child’s condition.

The most consistent features of Lennox-Gastaut syndrome are the clinical features and the pattern seen on an EEG. Diagnosis may take weeks or months.

Sometimes, LGS is a diagnosis of exclusion, which means that other diseases have to be ruled out before a child is diagnosed with it.

To diagnose children who have seizures, healthcare providers will generally look at:

  • Medical and neurological evaluations
  • The child's seizure history
  • The child's other medical problems (if any)
  • Brain imaging
  • EEG results
  • Blood test results
  • Lumbar puncture results (possible)

Clinical History

If your child has several types of seizures and they're frequent, especially if there is a cognitive or physical delay, your healthcare provider will consider a diagnostic workup for a syndrome such as Lennox-Gastaut syndrome or West syndrome. 

Brain Imaging

Most children who have seizures will have brain imaging, which can include a computed tomography (CT) scan, magnetic resonance imaging (MRI) scan, or ultrasound. MRI is considered the most detailed of these tests, but it requires a child to lie still in the machine for about half an hour, which may just not be possible for many children.

For young kids, healthcare providers may order a CT scan instead. For babies, an ultrasound may be a better option. It's faster and can identify early problems with brain development. 


In many cases of LGS, an EEG will show a distinctive slow spike wave and pattern when a seizure is not happening. Not everyone with the condition has this pattern, though. When someone with LGS is actively having a seizure, the EEG pattern is generally consistent with the seizure type. 

Blood Tests

Often, blood tests to evaluate for an infection or a metabolic disorder are part of the initial evaluation of seizures. If your child with Lennox-Gastaut syndrome has a sudden worsening of seizures, his or her healthcare provider will check to see if there is an infection, which can produce more seizures in people with epilepsy. 

Lumbar Puncture

As part of the initial evaluation, your child may have a lumbar puncture, which is a test that examines the cerebrospinal fluid surrounding the brain and spinal cord. The fluid is collected with a needle inserted into the lower back.

The procedure is uncomfortable and can be stressful or scary for children, particularly if they're cognitively delayed or cannot understand the diagnostic process. If your child’s healthcare provider strongly suspects a brain infection or inflammatory disease, they may want to perform this test while your child is under anesthesia.


LGS is a complex, lifelong condition that is not curable, and its seizures are difficult to control. Even with medication, most people with the condition continue to have some episodes. However, treatment is necessary, as it can reduce seizure frequency and severity. Additional treatments include the ketogenic diet and epilepsy surgery.


Specific medications are used to control the seizures of Lennox-Gastaut syndrome, as many of the usual anti-seizure drugs are not effective.

Medications used for seizure control in LGS include:

  • Benzel (rufinamide)
  • Depakote (valproate)
  • Felbatol (felbamate)
  • Fintepla (fenfluramine)
  • Klonopin (clonazepam)
  • Lamictal (lamotrigine)
  • Onfi (clobazam)
  • Topamax (topiramate)

Despite these anticonvulsant options, people with Lennox-Gastaut syndrome often continue to suffer from persistent seizures. Some of the medications used for LGS seizure control can have serious side effects, and they are reserved for especially difficult-to-control cases.

Cannabis has gained a great deal of attention as a treatment for childhood epilepsy. In 2018, the U.S. Food and Drug Administration (FDA) approved Epidiolex (cannabidiol or CBD) for treatment of seizures in patients with LGS.

Ketogenic Diet 

The ketogenic diet is a high-fat, low-carbohydrate diet that can help control seizures in people who have hard-to-manage epilepsy. It can reduce seizure frequency and severity in LGS, and it can make it possible to reduce the dose of anti-seizure medication. 

The diet itself is not easy to follow because of the carbohydrate restriction, and it may not be practical for many, including children who often favor carbohydrate-rich foods.

Epilepsy Surgery 

Epilepsy surgery is an option for some people with refractory epilepsy (that which does not improve with medication) caused by LGS. Procedures include surgeries in which the seizure-promoting region of the brain is removed.

Another option is corpus callosotomy, which involves an incision in the corpus callosum (the area that connects the right and left sides of the brain) to prevent the spread of seizures.

Placement of devices such as a vagal nerve electrical stimulator (VNS) may also be considered to prevent seizures. Your child may benefit from one of these types of brain surgery, and pre-surgical testing is needed to determine whether there is a chance of improvement.


If your child has LGS, you'll likely have to deal with many medical, social, and behavioral issues as your child gets older. This is not an easy situation for anyone. You may need help from others to care for a person who has LGS.

As you embark on this challenge, there are several strategies you can use to optimize your child’s medical condition and quality of life—and to ease the burden on you.

Understand the Disease

While not everyone has the exact same outcome and prognosis, there are certain things you can expect. It helps to familiarize yourself with the disease and its probable course so you can anticipate medical, behavioral, and emotional challenges as your child gets older. 

Get to Know Your Medical Team

You will need to see a lot of practitioners and healthcare providers over the years to manage your child’s condition. It will help your child if you understand the role of each team member, who should be contacted in what type of situation, and who will maintain care of your child for short versus long periods of time.

Some children with LGS continue to see their pediatric neurologists as they enter adulthood, and some move to the care of an adult neurologist. This depends on the availability of neurologists in your area and their specialization in epilepsy, as well as your preference.

Communicate With Your Child's School

Your child’s education and social adjustment may be a challenge. If possible, look for a school that has resources geared toward epilepsy, as well as learning and behavioral disabilities.

Maintain close communication with the staff members who oversee the services that your child needs, and stay in contact with teachers and your child’s aids. Listen to feedback and understand that your child may need to change schools.

Get Help

Taking care of someone with a disability is exhausting. If you can get help from family members, friends, volunteers, or a professional caregiver, this can provide you with relief and give your child or adult with LGS some variety and a fresh perspective. 

You might also consider looking for a day camp or daycare where your child can interact with other kids and receive proper care while you work or take care of other responsibilities.

Living Arrangements

If physically caring for your child with LGS is becoming impossible, you may need to seek alternative living arrangements. Many parents opt for this due to their own health issues, to devote more time to other children, the need to work, or an inability to deal with behavioral problems.

You can search for and research assisted living centers by talking to your healthcare providers, speaking with current or former patients, and interviewing staff and leadership. Once your child moves to a living facility, you can visit and maintain a close relationship.

Support Groups

LGS is a rare disease, and meeting others who are dealing with it can give you and your child resources and support as you navigate the illness throughout the upcoming years. Support groups are a great place to find this.

If you don't have any support groups near where you live, you may be able to find one you like online.

A Word From Verywell

LGS is a rare neurological disorder that has a major impact on a person’s life and the life of their whole family. Resources are available to help you get the best care possible. As a caretaker, it's important for you to have time off. Be sure to reach out for the help you need and practice self-care.

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  1. Zogenix Inc. FINTEPLA® (fenfluramine) oral solution.

Additional Reading

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.