An Overview of Lennox-Gastaut Syndrome

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Electroencephalogram (EEG) on a 4-year old girl. Epilepsy tracing on the screen.
AJ PHOTO /BSIP / Getty Images

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. 

LGS continues into adulthood, although there are some changes in the symptoms as people get older.  Children often have many different types of seizures, while adults tend to have fewer types  and less frequent seizures. Often, people with LGS have cognitive impairment and sometimes, physical abilities are compromised as well, which can interfere with independence.

While you can live well into adulthood and older age with LGS, there is a moderately higher risk of dying due to issues such as injury, seizures, medication side effects, or health problems, such as infections.


The symptoms of LGS begin in early childhood, typically before the age of four. Seizures are the most prominent symptom, and most children who have LGS also have a delay in developmental milestones. 


One of the hallmarks of LGS is that children have several types of seizures. With LGS, the seizures occur frequently, on a daily basis or even more, which is much more frequent than with most other types of epilepsy. 

Seizures may be preceded by an aura, which is a sensory change or a feeling that a seizure may happen. It can be difficult for someone who has a cognitive impairment to notice an aura. However, parents and siblings might learn to recognize signs that a seizure is likely to occur. Often, a person who has had a seizure may feel groggy afterward or may be unaware that a seizure occurred. 

Types of seizures that occur with LGS include:

  • Tonic seizures: Tonic seizures may or may not involve some impairment in level of consciousness. These types of seizures are characterized by sudden rigidity of the muscles, often with recurring relaxation and stiffness often lasting less than 20 seconds. . 
  • Atonic seizures: These seizures are characterized by loss of muscle tone, and may result in falling and loss of consciousness. 
  • Myoclonic seizures: Myoclonic seizures are very brief spasms, that can affect arms and/or legs, usually not associated with impairment or loss of consciousness.lasting no more than a second or two.
  • Absence seizures: Also often referred to as petit mal seizures, these seizures are not associated with physical movements, but rather by unawareness of surroundings. People may appear to be spacing out during an absence seizure, and unlike atonic seizures, they typically do not lose muscle tone or fall, and usually remain still in a seated or lying down position. You might not know how often your child with LGS is experiencing absence seizures, because they are often brief and unnoticeable.
  • Tonic-clonic seizures: While it is not the most common seizure type in LGS, a person with LGS can experience tonic-clonic seizures, also often referred to as grand mal seizures. These seizures are characterized by involuntary jerking movements of the body, usually lasting for a minute or longer, often with loss of consciousness afterward or fatigue and impaired recollection of the seizure. 
  • Status epilepticus: A person with LGS is more likely to experience status epileptics than are people who have other types of epilepsy. Status epilepticus is a seizure that does not stop on its own and requires medical intervention, usually with an intravenous (IV) or injected anti-seizure medication. Children and adults with LGS can experience status epilepticus with generalized tonic-clonic seizures, absence seizures, or tonic seizures.
  • Infantile spasms: A type of seizure that often precedes the diagnosis of LGS, infantile spasms are sudden jerks that occur in very young babies. They may be associated with impairment of consciousness, but it is hard for parents to recognize that they are seizures because babies may continue to cry when having these movements. 

    Developmental Delay 

    Children who have LGS also experience a developmental delay. This can include a range in the severity of cognitive delay and physical delay, generally with long-term impairment of cognitive skills, physical abilities, or both.


    There are several known causes, including disorders of brain development, neurological conditions, and damage to the brain during fetal development or shortly after the birth of a child. However, sometimes no cause can be identified.

    West Syndrome

    It is estimated that 20 percent to 30 percent of children with LGS have West syndrome, a condition characterized by a triad of infantile spasms, developmental regression, and a pattern of erratic brain activity on electroencephalogram (EEG) which is described as hypsarrhythmia. There are many causes of West syndrome, and children who have both LGS and West syndrome may need treatments for both conditions. Children with West syndrome are often treated with adrenocorticotrophic hormone (ACTH) or steroid treatment. 

    Tuberous Sclerosis

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


    Children who experience oxygen deprivation prior to or shortly after birth often experience consequences that affect brain development and function. This can manifest with a variety of problems, including LGS with or without West syndrome and cerebral palsy. 

    An infection or inflammatory disease of the brain is likely to cause persistent problems, and LGS can be one of those problems. 

    Cortical Dysplasia

    A type of abnormal brain development that occurs before a baby is born, cortical dysplasia is characterized by brain malformations, and can cause LGS. Cortical dysplasia can be caused by genetic or hereditary problems, lack of oxygen or blood flow to the baby, or there may or be an identifiable reason.


    It is emotionally difficult to find out that your child has LGS. Most parents already have an idea that something serious is going on because of the repeated seizures and the developmental problems. Yet, most parents also wish to hear that there is a minor cause behind the symptoms that can be easily cured with medication or surgery. If your child has symptoms of LGS, rest assured that your child’s doctors 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 LGS are the pattern seen on an electroencephalogram (EEG) and the clinical features. 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 LGS.

    Most children who have seizures will have a medical and neurological evaluation, which includes a careful history of the seizures, a history of other medical problems, brain imaging and an EEG as well as blood tests and possibly a lumbar puncture.

    Clinical History

    If your child has several types of seizures and has frequent seizures, especially if there is a cognitive or physical delay, your doctor will consider a diagnostic workup for a syndrome such as LGS or West syndrome. 

    Brain Imaging

    Most children who have seizures will have brain imaging, which can include a brain CT scan, a brain MRI, or a brain ultrasound. A brain MRI is considered the most detailed of these tests, but it requires a child to lie still in the MRI machine for about half an hour. This is not possible for many young children or for babies. Young children may have a brain CT scan instead, and young babies may have an ultrasound of the brain, which is a faster test that can identify problems with brain development at a young age. 


    The EEG pattern in LGS is characterized by interictal (when a seizure is not happening) slow spike wave and patterns. This can be very helpful in the diagnosis of LGS, although a person can have LGS even without this pattern. 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. And, if your child with LGS has a sudden worsening of seizures, his or her doctor will check to see if there is an infection, which can produce more seizures in people who have 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, the fluid that surrounds the brain and spinal cord. This is a test that requires collecting the fluid with a needle placed in the lower back.

    The procedure is a bit uncomfortable and can be stressful or scary for children, particularly children who are cognitively delayed and who cannot understand the diagnostic process. If your child’s doctor has a strong suspicion of an infection of the brain or an inflammatory disease, then your child may need to have this test while under anesthesia. 


    The seizures of LGS are difficult to control, and even with medication, most children and adults with the condition continue to have some seizures. However, treatment is necessary, as it can reduce seizure frequency and severity. There are several anticonvulsant medications that are more useful for the treatment of LGS than others. Other strategies for treatment include dietary modification with the ketogenic diet and epilepsy surgery. 


    There are specific medications used to control seizures of LGS, as many of the usual anticonvulsants are not effective. Some of the medications used for LGS seizure control can have serious side effects, and they are reserved for people who have difficult to control epilepsy. Medications used for seizure control in LGS include  Topamax (topiramate), Lamictal (lamotrigine), Klonopin (clonazepam), and Felbatol (felbamate).

    Despite these anticonvulsant options, people with LGS often continue to suffer from persistent seizures.

    Cannabis has also gained a great deal of attention as a treatment for childhood epilepsy, with recent FDA approval  (June 2018) of Epidiolex (cannabidiol or CBD) for treatment of seizures in patients with LGS.

    Ketogenic Diet 

    The ketogenic diet is a high fat, no carbohydrate diet that can help control seizures in people who have hard to manage epilepsy. It can reduce seizure frequency and severity among people with 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 be more practical for children and adults who are dependent on others for their needs, such as food.

    Epilepsy Surgery 

    Refractory epilepsy is epilepsy that does not improve with medication. Epilepsy surgery is an option for some people with refractory epilepsy caused by LGS. Procedures include surgeries in which the seizure-promoting region of the brain is removed to stop seizures. Another procedure, a corpus callosotomy, involves a lesion 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, there is a strong chance that you will have to deal with many medical, social and behavioral issues as your child gets older. This is not an easy situation for parents or for a child. Siblings or other relatives may step in to care for a person who has LGS as well.

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

    Understand the Disease

    LGS is a complex, lifelong condition that is not curable. 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 probable disease course so that you can anticipate medical, behavioral and emotional challenges as your child gets older. 

    Get to Know Your Medical Team

    You will need to see many doctors and health care 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 a short versus a long duration of time

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

    Communicate With Your Child's School

    Your child’s education and social adjustment may be a challenge. Parents of children with LGS can look for a school that has resources for learning and behavioral disabilities and epilepsy. Maintain close communication with the administrative staff members who oversee the services that your child needs, and maintain contact with teachers and your child’s aids. Listen to feedback and understand that you may need to make changes in where your child attends school if the resources are limited or not suitable.

    Get Help at Home

    Taking care of an adult 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. 

    Day Care

    You might consider looking for a day camp or a day care where your child can interact with others and receive 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 parental illness, parental childcare responsibilities, parental work responsibilities, or behavior that is impossible to manage at home or without professional oversight. You can search and research for an assisted living center by talking to your healthcare providers, speaking with patients who are staying there, and interviewing staff and leadership. Once your child moves to a living facility, you can visit and maintain a close relationship with your son or daughter. 

    Support Groups

    LGS is a rare disease, and meeting others who have been through it can give you and your child advice, resources, and friendships as you navigate the illness throughout the upcoming years. 

    A Word From Verywell

    LGS is a rare neurological disorder that has a major impact on a person’s life and the life of the whole family. If you have a child or sibling with LGS, you already know that this is a lifelong disease which comes with many difficulties.

    There are resources available to help you and your family get the best care possible as you steer your way through the changes and setbacks that are a part of this condition.

    Be sure to take care of yourself by not expecting perfection from yourself and by tag-teaming with others so that you can get breaks.

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