Health Library

Lennox-Gastaut Syndrome

Seizures associated with LGS begin between the ages of 1 and 7. In children, the incidence is estimated at 2 per 100,000. LGS accounts for only 1-8% of all childhood epilepsies. It is slightly more common in boys than girls.

This epilepsy syndrome is named after two researchers who helped the medical field identify and understand it.

What Causes Lennox-Gastaut Syndrome?

In many cases, doctors cannot identify a cause for LGS. Unknown genetic factors may play a role in such cases.

In other patients, the cause is known and can include:

• Injury at birth
• Trauma
• Malformations in the brain
• Tuberous sclerosis complex
• Infection of the brain tissue (encephalitis) or the covering of the brain (meningitis)

What are the Symptoms of Lennox-Gastaut Syndrome?

Most people with LGS have seizures every day. Sometimes they have them many times a day or in clusters. These can include many different types of seizures:

• Tonic seizures involve stiffening of the body and/or extremities (arms or legs). As with other seizures, they may occur when the person is awake or asleep. If they happen while standing or sitting, the person may fall to the ground. These seizures last from a few seconds to about a minute.
• Atonic seizures involve a sudden loss of muscle tone. Sometimes called a “drop attack,” these can cause a person to fall suddenly or drop things. Other symptoms can include the head dropping down or eyelids drooping.
• Myoclonic seizures involve sudden, shock-like muscle contractions affecting one or more limbs. These seizures may happen once or in clusters, with more than one occurring in a short period of time.
• Atypical absence seizures involve periods of interruption of consciousness. They typically begin and end very slowly. This makes them very hard to identify.
• Focal seizures (also called “partial seizures”) involve jerking of the face and / or an arm or leg, or another part of the body. Sometimes there are other signs. They may or may not progress to a convulsive seizure that affects the entire body.
• Tonic-clonic seizures, sometimes called a “grand mal seizure,” cause a loss of consciousness or change in awareness. This type of seizure has two phases. One phase is a tonic phase, in which the person’s muscles stiffen and they fall to the floor. Phase two is a clonic phase, which involves repeated, rhythmic jerking of the body. The person’s arms and usually legs begin to jerk. Sometimes the person loses control of their bladder or bowel.

Seizures or clusters of seizures in LGS can sometimes last for long periods. This is an emergency condition called “status epilepticus.”

The types of seizures a child has may change over time. Your child’s doctor will work to identify the seizure types your child has to create a personalized treatment plan.

Other Conditions Associated with Lennox-Gastaut

Most children with LGS also experience cognitive impairment, behavior problems and/or developmental delays. These may not be obvious until seizures begin. These problems can be caused by complex, underlying disturbances in how the child’s brain functions. They may be caused by the seizures themselves, or the medication needed to control the seizures. It can be hard for doctors to determine what is causing LGS in a child.

Young children with LGS may have behavior issues like poor social skills, aggressiveness and unstable moods. They may have personality disturbances, mood instability, and a slower-than-normal rate of psychomotor development. These can be caused by the effects of the medication, difficulty interpreting information, or continued electrical disturbances in the brain.

About 30% of children who have LGS also have a history of infantile spasms.

How is Lennox-Gastaut Syndrome Diagnosed?

LGS can be hard to diagnose because it may take years for different symptoms to develop. For a doctor to diagnose someone with Lennox-Gastaut, three factors must be present:

• Multiple seizure types.
• A distinct electroencephalogram (EEG) pattern.
• Moderate to severe cognitive impairment, behavior problems, and/or developmental delays.

To diagnose LGS, the medical team will:

• Ask questions about the child’s birth, seizure history and health history.
• Complete a physical and neurological exam.
• Perform a magnetic resonance imaging (MRI) of the brain.
• Perform an electroencephalogram (EEG) while the child is awake and asleep.
• Order blood tests.

Rarely the team may order additional tests.

How is Lennox-Gastaut Syndrome Treated?

The goal for patients with LGS is to achieve the best quality of life with the fewest seizures, negative treatment effects and medications.

Controlling seizures caused by LGS can be challenging. Two or more seizure medications are usually needed. Even then, the medicines may only provide partial relief. Some patients with LGS have benefited from new seizure medications in recent years.

“Rescue medications” help stop or shorten seizures or clusters of seizures.

Other treatment strategies also have been helpful for some children. These can include:

• Vagus nerve stimulation, in which a surgeon implants a device below the collarbone. The device reduces the frequency of seizures and keeps a seizure from progressing.
• Dietary therapies, including the ketogenic diet and modified Atkins diet.
• Corpus callosotomy, a surgery that involves cutting the corpus callosum, a band of nerve fibers that connects the two halves of the brain.

Lennox-Gastaut Syndrome Prognosis

Every child with LGS is different. It is not possible to predict what each child’s needs will be long-term. However, people who have LGS will require life-long care due to their seizures and cognitive impairment, behavior problems and/or developmental delays.

School-aged children with LGS typically need special services at school or in a therapy setting. As people with LGS grow into adulthood, day programs or residential programs may be needed, especially if their cognitive or behavior problems worsen. Caring for someone with LGS can take a toll on family members. It is essential that they find support and resources to help them on this journey.