What is Lennox Gastaut Syndrome?

Lennox-Gastaut syndrome (LGS) is a rare type of epilepsy that affects around 1 to 5% of children who have childhood epilepsy. This condition is mainly diagnosed between 3 and 5 years of age and  is slightly more common in boys.

Many children with LGS will also develop learning or behavioural difficulties, which may appear before they have seizures. Lennox Gastaut is rare and so it’s very common for people to not have heard of it before. If a family member is facing a new diagnosis, you probably have lots of questions so let's take a closer look.

How does Lennox-Gastaut syndrome differ from other types of epilepsy?

Up to 90% of people with LGS have seizures. This epilepsy usually includes more than one kind of seizure, and it may be difficult to control. These seizures will vary among individuals, and can include:

About 2 or 3 out of 10 children will develop LGS after having infantile spasms. In more than 60% of LGS cases, people will experience “status epilepticus”. This occurs when a seizure lasts more than 5 minutes, or when a person has repeated seizures, without gaining consciousness in between. It can be scary to witness a loved one in status and we recommend talking to your doctor about this so that, if needed, you are able to recognise it and seek treatment.

What causes Lennox-Gastaut syndrome?

There are many causes of LGS, which aren’t always easy to identify. Around 70% of LGS cases result from an earlier disease, injury, or event. Some of these causes happen before a child is born. Others causes are linked to events in early childhood. About 10 to 30% of children with LGS have a medical history of infantile spasms. In 30 to 35% of LGS cases, no cause can be found.

Examples of recognised causes for LGS include:

  • Brain development problems before birth
  • Traumatic brain injuries or concussions
  • Infections like meningitis or encephalitis that damage the brain
  • Inherited metabolic conditions
  • Brain damage from lack of oxygen before or during birth
  • Tuberous sclerosis complex
  • Brain tumours
  • Infantile spasm: another type of epilepsy that can develop into LGS).
  • Ohtahara syndrome [early infantile epileptic encephalopathy (EIEE)].

How can it be diagnosed?

The types of seizures a child is experiencing can be a key indicator of LGS,  especially a combination of tonic, atonic and atypical absence seizures.

Doctors will look at a person’s medical history, and carry out a detailed clinical evaluation, as well as physical and neurological tests. The results will help to identify developmental delays or intellectual disability. Imaging tests may include:

  • An electroencephalogram (EEG) is used to detect any abnormal patterns in the brain’s electrical impulses. The patterns are known as “slow spike and slow-wave” and “fast spike activity”. These can often be seen in between LGS seizure activity.
  • Magnetic resonance imaging (MRI) can provide detailed images of the brain and the body’s organs.

Genetic testing can also be used to identify a positive genetic diagnosis in up to 40% of children with unexplained LGS.

What are the effects of Lennox-Gastaut syndrome?

The effects on children with LGS can vary from child to child. Complete recovery from seizures is very rare but different treatment options are available. Seizures in LGS often damage the brain, which can unfortunately also lead to learning difficulties and developmental delays.

Does it affect life expectancy?

Since LGS is a lifelong condition, and it’s very likely that children will need continued support for their medical, learning and behavioural challenges throughout their life. Overall, children with LGS tend to have shorter life expectancy than the general population as they are at higher risk for more severe seizures, leading to status epilepticus or potentially SUDEP.

Are there treatments available and is there a cure?

Since there is no cure for LGS, the main goal of LGS treatment is to reduce or eliminate the seizures. As LGS can be difficult to treat with anti-seizure medication (ASMs), so most children will need a combination of different ASMs.

Epilepsy in children with LGS may improve initially with medication, however, as they get older, they could also try alternative therapies such as such as the ketogenic diet, brain surgery and vagus nerve stimulation therapy to help to control  seizures.

Behavioural issues in children with LGS may also require special attention from the family, and therapy from a psychologist or psychotherapist.

If you are caring for someone with LGS, your medical team and other professionals will help you to find the best treatment, social, management and educational plan to achieve the best for them. Although Lennox Gastaut syndrome is a rare condition, you are not alone. Find other parents to chat to on The Hub or reach out to us here if you need someone to talk to.