Lennox-Gastaut syndrome

This 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. It is also known as an ‘epileptic and developmental encephalopathy’ because the epileptic seizures and the abnormal EEG are thought to be important in these childrens’ developmental delay and learning difficulties. The most common time for Lennox- Gastaut syndrome to start is between 3 and 5 years of age although it can start as early as 18 months or as late as 7 years of age.

Symptoms

The seizures children experience can vary and care-givers will usually describe a number of different types of seizure for each child.

The most common types are atonic and tonic seizures. These used to be called ‘drop attacks’ or ‘drop seizures’ because the child will always ‘drop’. During these, the child will suddenly fall to the ground, which may at first be mistaken as tripping up or poor balance.  In an atonic seizure the child will fall as if a puppet’s strings have been cut. In a tonic seizure, the body and limbs will stiffen and the child will fall like a tree being cut down. These seizures usually happen many times a day and are very upsetting as the child is often injured during them. Injuries can be to the face, teeth and head.

Another common type is an atypical absence seizure, 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, rapid eye-blinking or head turning to one side. 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.

A focal (previously called partial) seizure is another common seizure type.  Most focal seizures start in the temporal lobes and can show themselves in many different ways. Both focal and tonic seizures occur commonly during the night when the child is asleep.

Children with Lennox-Gastaut syndrome also have other types of seizures including generalised tonic-clonic  and myoclonic seizures. Myoclonic seizures are the least frequent seizure type in this epilepsy syndrome. The generalised tonic-clonic seizures may be prolonged and form a state called convulsive status epilepticus. This is a medical emergency and must be treated urgently.

All children with Lennox-Gastaut syndrome will develop learning difficulties that will be moderate to severe in degree. Some children will even have developmental delay or learning difficulties before the seizures start. Most children will need to attend a special school and this is often from quite a young age of 5 or 6 years.

About 2 or 3 out of 10 children will develop Lennox-Gastaut syndrome after having West syndrome (infantile spasms).

Diagnosis

The diagnosis may be made by the age of 2 years but it becomes clearer with time. The electroencephalogram (EEG) test is very helpful as it will often show typical abnormalities. The abnormalities may be seen between seizures (called the ‘inter-ictal’ EEG) and the time of a seizure (called the ‘ictal’ EEG). The inter-ictal EEG pattern is called, ‘slow spike and slow wave activity’ and the ictal EEG during a tonic seizure is called, ‘fast spike activity’.

Some children will be found to have a cause for their epilepsy. These include genetic conditions such as tuberous sclerosis complex or a brain malformation. They may also have had previous brain damage. Examples of these include following problems before or around the time of birth (caused by a lack of oxygen to the brain, or ‘hypoxic ischaemic encephalopathy’), 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

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

Sometimes ketogenic dietary therapy (often called the ketogenic diet) may be effective. If it is effective this often means that one or more of the child’s epilepsy medicines can be gradually withdrawn.

Corticosteroid drugs, called prednisolone or hydrocortisone, may be given for a few (2-6) weeks when seizures are particularly difficult to control.

Another medicine, called cannabidiol (Epidiolex) has recently been shown to be effective in the treatment of Lennox-Gastaut syndrome. The medicine reduces the number of the different seizures the child has, particularly the atonic and tonic seizures. It may also help improve the child’s development, usually because they are having far fewer seizures. 

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 are likely to have prolonged or repeated seizures. This includes convulsive and non-convulsive status epilepticus. 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.

Outlook

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 involving a clinical psychologist or child psychiatrist. Some children will develop problems that include aspiration (where fluids and occasionally some soft foods get into the lungs) and repeated or severe chest infections which may shorten their life.

Support

Lennox-Gastaut Foundation
This organisation is based in America. As well as information, it offers a support group  for families across the UK. The group is hosted on Facebook and is private to families who live with LGS. 
Website: lgsfoundation.org

Tuberous Sclerosis Association
Advice and support for families affected by tuberous sclerosis.
Website: tuberous-sclerosis.org

Contact
Charity for families of disabled children.
Freephone 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 the Epilepsy Action Helpline.