Lennox-Gastaut syndrome

The Lennox-Gastaut syndrome is one of the most severe forms of childhood epilepsy. Several different kinds of seizures occur.

For about a third of children affected no known cause can be identified.

In some cases a cause is identified such as tuberous sclerosis, congenital infection, brain malformation, brain damage (due to birth asphyxia, meningitis or head injury) and some rare, metabolic diseases. Lennox-Gastaut syndrome does not usually run in families and the numbers of children affected is not known with certainty but it may account for some 10 per cent of all childhood epilepsies, and for up to 50 per cent of childhood epilepsies that do not respond to anti-epileptic drug treatment.

Symptoms
Seizures usually start between 2 and 5 years of age, but may start under two years. They rarely start after the age of 8.

The child's development is rarely normal before the seizures start. Often there is delayed development or other forms of epilepsy - 20 per cent of cases the child has previously had infantile spasms (West Syndrome). The first seizures are either atonic seizures (drop attacks) or atypical absences (child goes blank). Some children may have prolonged or repeated seizures very close together. This is called status epileptics and may need emergency help.

Atonic seizures
In these seizures there is a sudden loss of body tone and the child falls suddenly to the ground. At first these may be mistaken for tripping up or poor balance. Sometimes the child does not fall completely, but the head merely nods. These seizures build up in frequency until they are happening many times a day. As the child gets bigger they often hurt themselves during falls, cutting their chin, forehead or back of the head.

Atypical absences (blank spells)
These are episodes when the child goes blank and stares. Sometimes they are associated with blinking of the eyes, odd movements of the hands or nodding of the head. They are usually very brief, but extremely frequent. Sometimes they may appear so frequently as to merge into one another. This can go on for hours or even days. These episodes are called non-convulsive status epilepticus during which the child appears to 'switch off' completely, may dribble, is unable to feed or speak properly and could be very unsteady. Sometimes little twitches of the arms, legs or face can be observed.

Tonic seizures (stiffening)
During these attacks there is generally stiffening of the arms or legs, often associated with eyes rolling up or the head going back. Sometimes breathing is interrupted and the child may go blue. If the seizures lasts for more than 10-20 seconds then arms often start to tremble rapidly whilst remaining stiff. The child often falls backwards (or forwards) very suddenly.

Other seizures
As well as these three characteristic kinds of seizures children with Lennox-Gastaut syndrome often have other types of seizures such as generalised tonic-clonic and partial tonic-clonic seizures and complex partial seizures. Some children may also have very frequent jerks of the limbs or trunk. These are called myoclonic seizures.

Treatment
The Lennox-Gastaut syndrome is one of the hardest forms of childhood epilepsy to treat. There are many children for whom no anti-epileptic are effective and some children may need more than one anti-epileptic drug.
However, there are individuals for whom one or other of the available anti-epileptic drugs will be effective in reducing the number of seizures though the improvement is generally short-lived and rarely lasts for more than a year. Treatment with too many drugs should be avoided and if all the mainline drugs have been given a good trial then it is available to reduce treatment to one drug or at the most two.

The drugs that are frequently used are sodium valproate (Epilim), vigabatrin (Sabril), lamotrigine (Lamictal) and clobazam (Frisium).

A ketogenic diet (a high fat diet used with some younger children) may be effective in some cases and often less conventional therapies such as intravenous immunoglobin and steroids may be worth considering.
For children in whom repeated drop attacks are a problem, an operation to cut the corpus callosum (the large group of nerve fibres connecting the two halves of the brain) may be considered. This procedure is relatively safe, but it is not effective in every case and seizures may return in some children after several months or years of good control.

Outcome
The long term outcome is poor both in terms of seizure control and intellectual development. As seizures continue it becomes harder and harder for the child to cope in mainstream school and they gradually slip behind and have increasing learning difficulties. It is not clear whether they actually get worse in terms of learning abilities. What is most likely is that they fail to make progress because of all the lost learning opportunities. However, a small group of people (5 per cent) with otherwise typical Lennox-Gastaut syndrome grow out of their seizures by the time they are teenagers and subsequently will attain average or near average levels of ability.

The majority of children with Lennox-Gastaut syndrome will continue to have seizures, sometimes of the same type, sometimes changing to predominantly generalised tonic-clonic or complex partial seizures. Most of these people will have lower than average abilities and many will be dependent on others for some or all of the activities of daily living.