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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 1 comments or add yours


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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