Lennox-Gastaut syndrome (LGS) is a severe form of epilepsy that begins early in life. Individuals with the condition experience multiple types of seizures and have delayed intellectual development and behavioral problems.

A person with LGS may take medication to control seizures. Doctors may also recommend dietary therapy and surgical management.

This article discusses the causes and symptoms, treatment options, how doctors diagnose LGS, and more.

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There are many possible causes for LGS. A 2022 article cited statistics from an older study of children in Atlanta, United States, indicating that around 75% of those with LGS develop it due to an existing neurologic abnormality. This is known as secondary LGS.

Experts further divide LGS into three groups: structural causes, genetic disorders, and metabolic disorders.

Structural causes occur due to abnormal structures in the brain, such as congenital brain malformations, or as a result of acquired brain injuries due to an infection, such as encephalitis.

Certain genetic disorders, such as tuberous sclerosis complex, can cause structural changes in the brain. This can lead to LGS.

Rarely, metabolic disorders may lead to LGS.

There is no identifiable cause for about 25% of people with LGS.

Learn more about metabolic disorders.

LGS seizures begin in early childhood. They usually start when a child is aged between 3–5 years.

A person with LGS may experience multiple types of seizures. They include:

  • Tonic seizures: These are a distinctive feature of LGS and the most common seizure to occur with the condition. They involve stiffening of the body, upward eye gaze, altered breathing pattern, and dilated eyes.
  • Atypical absence seizures: These are the second most common subtype seen in LGS. They involve a period of unconsciousness and unresponsive staring spells lasting from 5–30 seconds, according to the Epilepsy Foundation.
  • Atonic seizures: Also called “drop attacks,” these are present in over half of people with LGS. The Epilepsy Foundation also indicate that atonic seizures can cause to become limp, and can cause recurrent falls and injuries.
  • Myoclonic seizures: These present as brief, jerking spasms of muscles or muscle groups.
  • Generalized tonic-clonic seizures: These cause muscle stiffness with rhythmic jerking.

Many people with LGS experience status epilepticus, which are prolonged seizures.

A child with LGS may have delays in motor milestones, such as sitting and crawling. They may also experience psychomotor regression, which is where they lose skills they have previously acquired.

LGS may also cause symptoms such as:

Learn more about types of epilepsy.

To diagnose LGS, a person must have the three critical features of LGS:

  • multiple seizures
  • characteristic electroencephalogram (EEG) pattern
  • cognitive impairment, developmental delay, or behavior problems

The doctor may begin by taking a full medical history, performing a physical examination, and asking questions about symptoms.

They may then order a series of laboratory and imaging tests. These can include:

An EEG with awake and sleep recording is also essential.

Learn about epileptic encephalopathy.

There are various treatments that a doctor may recommend for LGS.

Seizure medications

Treatment for LGS revolves around seizure control. Seizures in LGS can be difficult to control. Doctors usually prescribe two or more seizure medications to control seizures in people with LGS.

Medications proven helpful in reducing seizures in LGS include:

A doctor can recommend the most suitable medications and explain what taking them involves.

Learn more about seizure medications.

Dietary therapies

Dietary treatments may also reduce seizures in people with LGS. Different diets for LGS and other forms of epilepsy include:

A doctor may refer a person to a dietitian to help them to make dietary changes and ensure they get enough essential nutrients.

Learn about the differences between the keto and Atkins diets.

Surgical management

In rare cases, a person may require surgery, including the removal of a focal area of the brain to help with controlling seizures.

Brain surgery for LGS can include:

  • resection of tumors, tubers, or malformations
  • corpus callostomy
  • hemispherectomy

Vagus nerve stimulation may also be a suitable treatment for people with LGS. This involves placing a device in the chest and the left side of the neck. The device then uses electrical impulses to stimulate the vagus nerve, helping to control seizures.

A person’s doctor will advise on whether they feel surgery is an option for them and what type of procedure they recommend.

Learn more about different surgeries for epilepsy.

According to figures cited by the LGS Foundation, around 1–2% of all people have LGS. It affects around 48,000 children and adults in the United States.

Learn more about epilepsy in children.

Here are some frequently asked questions about LGS.

What is the life expectancy for Lennox-Gastaut syndrome?

According to some experts, LGS has a mortality rate of 3–7% over 8 to 10 years following diagnosis. Death can often happen as result of accidents, due to falls or other incidents relating to the syndrome.

Sudden unexpected death in epilepsy (SUDEP) may also be more common among people with LGS.

A doctor can advise on ways to reduce the risk of accidents and improve quality of life.

What triggers Lennox-Gastaut?

Various conditions can cause LGS. Possible causes include congenital brain malformations, infection, or genetic disorders, such as tuberous sclerosis complex.

What age does Lennox-Gastaut syndrome start?

Seizures in people with LGS typically begin in early childhood, usually appearing between the ages of 3–5 years.

What is the difference between epilepsy and Lennox-Gastaut syndrome?

Lennox-Gastaut syndrome is a severe form of epilepsy. It presents with different types of seizures.

Medical professionals consider it to be an epileptic encephalopathy. This means that there are other symptoms, such as developmental delays, as well as seizures.

Lennox-Gastaut syndrome (LGS) is a rare, severe form of epilepsy that usually begins in childhood. It presents with multiple types of seizures, cognitive or intellectual impairment, and a characteristic pattern on the EEG.

Existing brain abnormalities or injuries may cause LGS. The underlying cause is unclear in about 25% of cases.

Treatment for LGS focuses on seizure control with medications and dietary therapies. In some cases, a doctor may recommend brain surgery or vagus nerve stimulation.

It is best for a person to contact a doctor if they have concerns about LGS. The doctor will be able to order tests to confirm the diagnosis and rule out other possible causes.