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Lennox-Gastaut syndrome

This type of epilepsy syndrome is uncommon and occurs in between 1 and 5 in every 100 children with epilepsy. However, it is the most common type of intractable (difficult to treat) childhood epilepsy. The most common time for it to start is between 3 and 5 years of age although it can start earlier or later.


The seizures experienced can vary and care givers will describe a mixture of types for each child.

The most common type is atonic seizures or ‘drop attacks’. During these, the child will suddenly fall to the ground, which may at first be mistaken as tripping up or poor balance. These seizures usually happen many times a day and are very upsetting as the child is often injured during them.

Another common seizure type is atypical absence seizures, which can last from 10 seconds to several minutes. During these seizures the child will appear vacant or blank. They may have other features like head nodding, or rapid blinking. The child may have some awareness of what is going on around them. These seizures can be very frequent and can even merge to be constant, forming a state called ‘non-convulsive status epilepticus’. During these episodes the child will be described as ‘not being with it’, be drooling, unable or slow to speak, need help with feeding and be floppy or wobbly.

Another frequent seizure type is tonic seizures. They may only happen at night. During these, there will be a general stiffening of the arms and legs.

Children with Lennox-Gastaut syndrome may have other types of seizures including generalised tonic-clonic seizures, focal (partial) motor seizures, focal (partial) seizures with some loss of awareness, and myoclonic seizures.

All children with Lennox-Gastaut syndrome will develop learning difficulties that will be moderate to severe. Some children will have developmental delay or learning difficulties before the seizures start.

About 2 out of 10 children will develop Lennox-Gastaut syndrome after having West syndrome (infantile spasms).


The diagnosis becomes clearer with time. The EEG is very helpful as typical abnormalities are seen, even when the child is not having any obvious seizures.

Some children may have a cause for their epilepsy that can be identified. These include genetic conditions such as tuberous sclerosis complex or a brain malformation. They may also have had previous brain damage. Examples are after problems before or around the time of birth, meningitis as a young baby or a head injury. In about half of all children with Lennox-Gastaut syndrome, no cause can be found.


Treatment of Lennox-Gastaut syndrome is very difficult. The medicines that may be effective in some cases include sodium valproate (Epilim), lamotrigine (Lamictal), topiramate (Topamax), clobazam (Frisium) and phenytoin (Epanutin).

Sometimes ketogenic dietary therapy (often called the ketogenic diet) may be effective.

Courses of corticosteroid drugs are sometimes used when seizures are particularly difficult to control.

Some children who have repeated drop attacks may be offered a type of epilepsy surgery to reduce the number and severity of their seizures. This surgery will not make them seizure free. The two types of surgery that may be considered are corpus callosotomy and vagus nerve stimulation (VNS).

If your child has this syndrome they may have prolonged or repeated seizures. Your child’s doctor will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures.

There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.

Information about treatments for children can be found on the Medicines for Children website.


The long term outlook is poor in terms of seizure control and intellectual development.

A very small number of children will outgrow their seizures by their teenage years. However, the remaining children will continue to have seizures, often on a daily basis, into adult life. These children will be dependent on others for the rest of their life.

Behavioural problems are also very common and may need management from a specialist team. Some children will develop problems like repeated or severe chest infections which may shorten their life.


Lennox-Gastaut Support Group
Tel: 01664 454 305
Email: andrew.gibson15@btopenworld.com

Lennox-Gastaut Syndrome UK
Website: lgsfoundation.org.uk

Tuberous Sclerosis Association
Website: tuberous-sclerosis.org

Helpline: 0808 808 3555
Website: cafamily.org.uk
Email: info@cafamily.org.uk

What is a syndrome?

A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether the child has physical or learning difficulties, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.

If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact Epilepsy Action.


Epilepsy Action would like to thank Drs Richard Appleton and Rachel Kneen (at Alder Hey Children’s Hospital, Liverpool) and Stewart Macleod (at Yorkhill Children’s Hospital, Glasgow), consultants who specialise in children’s epilepsy, who have updated this fact sheet.


This information is exempt under the terms of The Information Standard.

  • Updated June 2016
    To be reviewed June 2019

Comments: read the 6 comments or add yours


My grandchild has just been diagnosed with infantile spasms and is just starting on steroids, but we are confused and very worried as it has taken five weeks to come to this diagnosis as there were no signs of IS on EEG but the video showed some sort of spasm or siezure, I am now extremely worried that my grandchild could get Lennox Gaustat syndrome and is four months old. Could someone please let me know if this syndrome is as bad as it sounds ...

Submitted by Annie on



This must be a worrying time for you and your family.


It would be best to talk to your grandchild’s consultant. They should be able to explain how they made the diagnosis and what they believe could happen in the future. The long-term outlook, depends mainly on the cause of the syndrome.


If we can be of any more help, please feel free to contact our helpline team directly. You can email helpline@epilepsy.org.uk  or phone the Epilepsy Action Helpline freephone 0808 800 5050. Our helpline is open Monday to Friday, 8.30am until 5.30pm.


Some families also find it helpful to contact, the charity Contact A Family for support.





Epilepsy Action Helpline Team

Submitted by rich on

Hi, my grandson has just finished his course of ACTH and starts his steriids today, is it common to have any spasms in the next few weeks.

Submitted by Annie on

Hi Annie

I’m sorry we’re not medically people so I can’t answer that question for you. Hopefully his nurse or doctor will be able to.





Epilepsy Action Helpline Team

Submitted by rich on

Hi, althought much of this information is correct it is misleading. Lennox Gastaut shows the 'onset' of the condition in childhood. It is a life-long condition and goes into adulthood. This should be stated.

There are no results to show EEG as there is a particular spike wave for this condition, which helps to confirm the condition AND with clinical observation of seizures.

Note: any operations for seizure control, such as Vegus Nerve stimulation, should be noted with the full facts, as this is misleading as a potential cure for this. This is very misleading to just state these without giving the full information for people on this website.
I wrote a letter to the professor that was researching VNS and she said that the studies were inconclusive and that they were not being carried out.
I contacted her after seeing an advert for this for severe epilepsy sufferers of someone trying to raise funds for this operation. At the time the operation was not available and also not stated are the dangers and consequences of this.
Stating this may give false hope to parents of sufferers, but people need to be shown the full facts.

The website shows constantly this is a childhood condition, and these websites have led to other professionals in the care system reading these and using these as diagnostic tools in the assessment of my son and insisted it was a childhood disease. This was an extremely dangerous diagnoses for people of little awareness of Lennox-Gastaut syndrome, and if i had not have been present this would have had disasterous consequences for my son. He is an adult and these healthcare professionals insisted he did not have the condition. This potentially would have changed his medication, and killed him.

Medical facts or medical literature should be added to any statements on this website to support what the lay person is stating on here and to not do this is errnoeous and dangerous for diagnostics of lennox-gastaut sufferers.

I have 28 years of experience of LG and with my adult son, who was diagnosed when little information was available as this was only identified in the 60's as a syndrome.
Websites like this are helpful but it needs medical literature to back up statements.

i would also like to point out that this website states: 'behavioural problems' with LG. Could this website state what these are? This information is picked up by the layperson and labels people with LG, particularly my son with behavioural problems. He does not display behavioural problems, just problems associated with the condition: learning disabilities, some autism, ataxia, slowness in response, particular to touch and sound.
To state 'behavioiural' is careless and very misleading.
His high IQ before the onset of this condition, helped him later in life when the conditon and the right medication, became less severe, and he could continue to read and write.
Also to determine length of life, or life expectancy is misleading, as speaking to a neurologist he said that multiple disability overloads will give a shorter life expectancy.

The sinusitus and chest infections may come from a medication used for the treatment of LG, and that is Lamotragine.

The medication stated by British National Formula states that any confinement using this medication requires Vit D supplements.

The medication prevents the manufacture of Vit D, and can lead to immune deficiencies and can see the onset of chest infections, and sinusitis as my son has had quite frequently. My son has been confined, and the professionals do not listen to this information, resulting in many chest infections for my son.

LG may not be directly related to the chest infections but it could be the medication. All medications for this should be published with all the contra-indications and side effects. Most information with side-effects only cover some of the problems not all.

Please publish this as a source of information.

Submitted by keyna leyland on

My son was diagnosed with a seizure disorder about 3 1/2-4 years ago when he was about 3 or 4 years old. No specific name. Still, we don't have a specific name to his seizures, but they do resemble almost every symptom of LG I've seen listed. He doesn't have drop seizures that I've been able to discern and he doesn't have the specific spike they look for on the EEG. Other than that, he is text book LG for sure. His neurologist even told me that the it this g keeping him from being diagnosed clinically with LG is the EEG. He is being treated with Onfi and Keppra.

Submitted by Brandy Hutchinson on

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