The cause of this syndrome is not known. It usually happens in children who already have epilepsy or another epilepsy syndrome. The epilepsies and epilepsy syndromes in which ESES can happen include Lennox-Gastaut syndrome, focal epilepsies and less commonly, self-limiting epilepsy of childhood with centro-temporal spikes (what used to be called 'benign Rolandic epilepsy of childhood' [BREC] or 'benign epilepsy of childhood with centro-temporal spikes' [BECTS]).

ESES may happen in children with an epilepsy syndrome for which no cause has been found. But it may also happen in children in whom a cause is known. These causes include brain damage following a lack of oxygen at birth, or following meningitis or encephalitis or a head injury.

It may also happen if the brain has formed abnormally. This is called cortical dysplasia and can involve some or all of the brain. ESES that happens in a child with previous brain damage or an abnormally formed brain is usually more difficult to treat.

There is an even rarer syndrome, called Landau-Kleffner syndrome, which also shows some features of ESES.

Symptoms

The first sign of any problem is usually that the rate of a child's learning appears to slow significantly. Many of the children begin to have problems with either the understanding of speech and language (this is called receptive dysphasia) or expressing their own thoughts (expressive dysphasia) in the form of spoken language. There may also be problems with reading and short-term memory. Some children can learn new information and tasks over the course of a few days or weeks but they then seem to lose what they had learned.

Epilepsy develops and different kinds of seizures can happen either during the day or during sleep. Many children will have atypical absence (blank) seizures, some will have myoclonic (jerk) seizures.

Others will have focal onset motor seizures (seizures involving jerks of one side of the body only). These focal onset seizures happen particularly during the night. However, some children with ESES do not have any seizures during the night.

Despite the fact that sleep patterns are often severely disturbed due to the seizures, children with ESES usually wake the next morning feeling refreshed.

Diagnosis

An EEG must be done to make the diagnosis. It shows continuous spike and slow wave epileptic activity during sleep, especially during part of sleep called 'slow wave' sleep.

This is often continuous and lasts for many minutes, even for the whole time the child is in slow sleep. This is why ESES is also called 'continuous spike-wave of slow sleep' (CSWSS). Slow wave sleep happens in deeper sleep after the child has been asleep for about 20 to 30 minutes.

Because of this, it would be unusual to record slow sleep during a routine EEG outpatient appointment. This is because a routine appointment only lasts 25-30 minutes and there is not enough time for a child to reach slow sleep, even if they do fall asleep!

If there is a suspicion of ESES, then the child will need a much longer outpatient appointment of at least one to two hours. Alternatively, the EEG would have to be recorded over the whole night. This can usually be done at home or, if necessary, in hospital.

The EEG is often abnormal when the child is awake but in some cases, it may be normal. It is the EEG finding during a child's deeper sleep (slow sleep) that gives the syndrome its name.

Metabolic (blood) tests, which look at the way the body works, usually give normal results. Magnetic resonance imaging (MRI) brain scans may be normal or show previous damage as mentioned above.

Treatment

It is important that all children with ESES are seen by a consultant in paediatric neurology. If seizures are a problem to the child, then epilepsy medicines may be suggested to control the seizures.

These include sodium valproate (Epilim), levetiracetam (Keppra), ethosuximide (Zarontin) and clobazam (Frisium). These medicines may also treat the ESES but this is less likely than the medicines reducing the number of, or completely stopping the seizures.

Sometimes prednisolone (a steroid medicine) may be effective in treating ESES but this medicine needs careful monitoring. There is another medicine called sulthiame (Ospolot) which may also be helpful. Only a specialist in paediatric epilepsy can prescribe these medicines.

For some children the CSWSS on their EEG does not respond to any medicines.

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.

Outlook

For most young people an improvement is seen in ESES in the early teenage years. The EEG may return to normal during slow sleep. The seizures become less frequent and may even go completely. At about this time an improvement in speech and language skills and learning is also seen.

However, this improvement does not always mean that they will then show normal learning. Some will be left with learning difficulties or behaviour problems, or both. Rarely, ESES may carry on throughout childhood and into adult life. If this happens, then the outlook for learning is worse.

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 they have physical or learning disabilities, 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.

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