Lennox-Gastaut Syndrome


Epilepsy is a disorder of the nervous system. Epilepsy causes sudden, intense bursts of electrical activity in the brain.

Lennox-Gastaut syndrome (LGS) is a type of epilepsy. Patients with LGS experience many different types of seizures including:

  • Tonic - stiffening of the body
  • Atonic - temporary loss of muscle tone and consciousness, causing the patient to fall
  • Atypical absence - staring episodes
  • Myoclonic - sudden muscle jerks


Symptoms of LGS can vary depending on the type of seizure the patient is experiencing.

Symptoms of a tonic seizure include:

  • Stiffening of the arms, legs or torso
  • Affecting both sides of the body
  • Falling

Symptoms of an atonic seizure include:

  • Sudden loss of muscle tone
  • Going limp and falling to the ground
  • Brief loss of consciousness
  • Drooping eyelids
  • Head nod
  • Jerking

Atypical absence seizure symptoms include:

  • Muscle weakness in the head, abdomen, arms or legs, often resulting in a gradual slump
  • Subtle jerking (myoclonic) movements
  • Loss of awareness

Myoclonic seizure symptoms include muscle spasms that are:

  • Sudden
  • Brief
  • Involuntary
  • Shock-like
  • Variable in intensity and frequency
  • Affect one part of the body or all over the body
  • Sometimes severe enough to interfere with eating, speaking or walking

Patients with LGS often have some amount of mental or behavioral challenges. This may include:

  • Developmental delays
  • Behavioral disturbances
  • Difficulty processing information

Causes and Risk Factors

LGS is most common in children between the ages of 2 and 7 years old. Boys are slightly more likely to be affected than girls.

In most cases the cause for LGS is known. Common causes include:


To be diagnosed with LGS the patient must have all three of the following:

  • A number of different seizure types
  • A specific brain wave pattern
  • Cognitive and/or behavioral challenges

The most useful way to diagnose seizures is an electroencephalogram (EEG). This records electrical activity in the brain. The EEG can record unusual spikes or waves in electrical activity patterns. Different types of epilepsy can be identified with these patterns.

Routine lab tests may be used to rule out other medical conditions that might be causing the seizures.

  • A complete blood count (CBC) will provide the doctor with information regarding infection, abnormal electrolyte levels (such as magnesium, potassium and calcium), kidney or liver malfunction or genetic conditions.
  • A lumbar puncture (spinal tap) can rule out infections, such as spinal meningitis and encephalitis.
  • A toxicology screening can show poisons, illegal drugs or other toxins.

Magnetic resonance imaging (MRI) and computed tomography (CT) scans may be used to look at the cause and the location within the brain. The scans can show scar tissue, tumors or structural problems in the brain.


LGS seizures can be difficult to treat. The seizures often do not respond to anti-seizure medications. Medications may be used in combination with a special diet and surgery.

Surgery may be an option if medication can't control the seizures. A vagus nerve stimulator (VNS) is sometimes implanted and used with anti-epileptic medication to lower seizures. The VNS is a tool placed under the skin of the chest. It sends electrical energy through the vagus nerve in the neck to the brain.

Certain types of epilepsy may be controlled with a ketogenic diet. This is a high-fat, low-carbohydrate diet used most often for children who have not responded to medications.

Corpus Callostomy is another treatment option. The corpus callosum is a band of nerve fibers located deep in the brain that connects the two halves (hemispheres) of the brain. It helps the halves of the brain share information, but it also contributes to the spread of seizure impulses from one side of the brain to the other. A corpus callostomy is an operation that cuts the corpus callosum, interrupting the spread of seizures. Seizures generally do not completely stop after this procedure. They will still happen on the side of the brain where they start. They will usually become less severe, as they can no longer spread to the other side of the brain.

A corpus callostomy may be performed in people with the most extreme and uncontrollable forms of epilepsy, when frequent seizures affect both sides of the brain. People considered for corpus callostomy are typically those who do not respond to treatment with antiseizure medications.

Candidates for corpus callostomy undergo an extensive pre-surgery evaluation—including seizure monitoring, electroencephalography (EEG), magnetic resonance imaging (MRI) and positron emission tomography (PET). These tests help the doctor pinpoint where the seizures begin and how they spread in the brain. It also helps the doctor to determine if a corpus callostomy is an appropriate treatment

The staff at the Cedars-Sinai Epilepsy Program will work with each patient to determine the best treatment option.

© 2000-2022 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
Looking for a Physician?

Choose a doctor and schedule an appointment.

Looking for Virtual Care?

Get the care you need from world-class medical providers working with advanced technology.

Want More Information?

Cedars-Sinai has a range of comprehensive treatment options.

Need Help?


Available 7 days a week, 6 am - 9 pm PT

Need Help?


Looking for a Physician

Choose a doctor and schedule an appointment.