Lennox-Gastaut syndrome (LGS; childhood epilepsy)

• What is Lennox Gastaut Syndrome
• Statistics on Lennox Gastaut Syndrome
• Risk Factors for Lennox Gastaut Syndrome
• Progression of Lennox Gastaut Syndrome
• Symptoms of Lennox Gastaut Syndrome
• Clinical Examination of Lennox Gastaut Syndrome
• How is Lennox Gastaut Syndrome Diagnosed?
• Prognosis of Lennox Gastaut Syndrome
• How is Lennox Gastaut Syndrome Treated?
• Lennox Gastaut Syndrome References

What is Lennox Gastaut Syndrome

Lennox Gastaut Syndrome (LGS) is a severe form of epilepsy which develops in childhood. Lennox-Gastaut Syndrome is characterised by:

• Multiple seizures (fits) of various types, which are usually difficult to control
• A specific pattern of brain activity on the electroencephalogram (EEG)
• Intellectual impairment.

Statistics on Lennox Gastaut Syndrome

Lennox-Gastaut syndrome is a rare condition. It makes up only 5% of all cases of childhood epilepsy. Lennox-Gastaut syndrome more commonly affects boys. The syndrome usually develops between 3 and 5 years of age, and only rarely develops after the age of 8.

Risk Factors for Lennox Gastaut Syndrome

The symptoms of Lennox-Gastaut syndrome are thought to be the result of a non-specific brain injury occurring during a crucial stage of development. In some cases of Lennox-Gastaut syndrome, a predisposing cause can be identified. For example, meningitis, head trauma, or bleeds into the brain may all predispose to LGS. About one quarter of children with Lennox-Gastaut syndrome will have a history of infantile spasms or West syndrome.
Lennox-Gastaut syndrome is not thought to be genetic. However, some patients will have a family history of epilepsy.

Progression of Lennox Gastaut Syndrome

The symptoms of Lennox-Gastaut syndrome usually develop between 3 and 5 years of age. Rarely, patients may develop LGS during adolescence. There are three main features of Lennox-Gastaut syndrome:

1. Multiple types of seizures (fits)
2. Characteristic EEG changes
3. Progressive cognitive (mental) deterioration.

The type of fits can vary amongst the patients. They include:

• Tonic fits (sudden contraction of the muscles)
• Atonic fits (sudden relaxation of the muscles, leading to ‘floppy’ baby or child)
• Atypical absence fits (blank staring spells)
• Myoclonic fits (sudden jerking movements)

The main type of seizure experienced can change over time. Most young children with Lennox-Gastaut syndrome experience atypical absence seizures, but with age, tonic fits may become more common. Approximately 90% of children with Lennox-Gastaut syndrome will have some intellectual impairment and developmental delay. This often worsens over time. Speech and language may be severely affected. In addition, psychosis, hyperactivity, aggression or autistic features may develop.

How is Lennox Gastaut Syndrome Diagnosed?

Any child who has multiple seizures will need investigation to try to determine a possible cause for the seizures. If the child is to be admitted, routine blood tests may be done, including full blood count, liver function, kidney function, blood glucose (sugar), and iron level.
Electroencephalogram (EEG): An electroencephalogram looks at the electrical activity of the brain through electrodes placed along the child’s scalp. This test is necessary because the criteria for the diagnosis of Lennox-Gastaut syndrome is based on the EEG results.
Magnetic resonance imaging (MRI) This is an imaging test of the brain. It is important if Lennox-Gastaut syndrome is suspected because it may help identify any congenital malformations or past injury to the brain which may have contributed to the development of Lennox-Gastaut syndrome.

Prognosis of Lennox Gastaut Syndrome

The prognosis of LGS varies between individuals. In some patients, seizure activity may be well controlled, allowing good intellectual and behavioural development. However, in approximately 80% of patients, seizures are difficult to control. Ongoing seizures impair development and intellectual functioning. The progressive intellectual impairment associated with Lennox-Gastaut syndrome means that many patients require full-time care throughout life. The short-term mortality of Lennox-Gastaut syndrome is approximately 4-7%. This is largely due to seizure-related fatal accidents.

How is Lennox Gastaut Syndrome Treated?

There is no cure for Lennox-Gastaut syndrome, only symptom control. Unfortunately, seizure control is often difficult to achieve, and no one anti-epileptic drug has been found to be highly effective.
Drug treatments
 
Many drugs have been studied for the treatment of Lennox-Gastaut syndrome. At the moment, it is thought that a combination of sodium valproate with either topiramate or lamotrigine may be the best treatment.
Non-drug treatments
Other than drug treatment, a multidisciplinary team approach is essential in management of patients with LGS. Supportive modalities such as special education, support group, psychological counselling for the carers, and other health care professionals need to be involved.
Sometimes surgery may be helpful in patients with treatment resistant cases.
When used under supervision, a ketogenic diet (a diet high in fat, with adequate protein and low carbohydrate) may reduce seizure frequency in some patients, and even improve behaviour symptoms.

Lennox Gastaut Syndrome References

1. Braunwald, Fauci, Kasper, Hauser, Longo, Jameson. Harrison’s Principles of Internal Medicine. 16th Edition. McGraw-Hill. 2005.
2. Camfield P, Camfield C. ‘Epileptic syndromes in childhood: Clinical features, outcomes, and treatment.’ Epilepsia 2002;43:27-32
3. Collier J, Longmore M, Brinsden M. Oxford Handbook of Clinical Specialties. 7th edition. Oxford University Press. 2006.
4. Guerrini R. ‘Epilepsy in children.’ Lancet 2006;367(9509):499-524
5. Hancock, E, Cross, H. ‘Treatment of Lennox-Gastaut syndrome.’ Cochrane Database Syst Rev 2003
6. Wheless JW, Constantinou JE. ‘Lennox-Gastaut Syndrome.’ Pediatr Neurol 1997; 17:203