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.
Other names for Dravet syndrome
• Severe myoclonic epilepsy in infancy (SMEI)
Dravet syndrome is a very rare form of childhood epilepsy. Out of 500 children with epilepsy, only one, or at most two, children are likely to have this form of epilepsy. The epilepsy usually starts with seizures that may seem to be very similar to febrile convulsions. The more typical features of Dravet syndrome usually become more obvious during the second year of life.
Epilepsy Action has more information about febrile convulsions.
The seizures begin in the first year of life. They are most often associated with a high temperature (febrile convulsion). They often involve just one side of the body, although both sides of the body may be involved. The seizures are characterised by stiffness and jerking (called a tonic-clonic seizure), or just repeated jerking (called a clonic seizure). Febrile convulsions in Dravet syndrome are usually quite long, sometimes lasting for 15 or 30 minutes, or even longer. They often happen repeatedly in the first year of life. However, at this time it can be difficult to differentiate these children from others with briefer febrile convulsions, who do not go on and develop other types of seizure.
During the second year of life the seizures become more frequent and persistent, and are often more obviously focal (also called partial) involving one part of the body. They may happen with or without a fever, and at any time of day and night. In addition to the tonic-clonic seizures, myoclonic seizures (‘myo’ meaning muscle, and ‘clonus’ meaning jerk) and focal seizures become common. Often the children are photosensitive (have seizures brought on by flashing or flickering lights). Seizures may also sometimes be brought on by hot environments or hot showers or baths. The early development of children with Dravet syndrome is usually normal. However, the child’s development starts to slow down and children may lose skills towards the end of the second year of life. The child’s speech and language is particularly affected.
A full history and description of the seizures that have happened in the past and at the time the child attends their hospital appointment is very important. It is also important for parents to give the doctor a detailed account of their child’s development.
The EEG, which records the electrical activity in the brain, is usually normal early on in this condition. By the time the child is 18 months old, the EEG shows evidence of epileptic activity, with spike and wave or polyspike discharges. These happen either as a single event, or in bursts. They may be generalised involving the whole brain, or happening just from one small area of the brain. Some, but not all, children with Dravet syndrome show EEG evidence of sensitivity to flashing or flickering lights, called photosensitivity. Brain scans in children with Dravet syndrome are usually normal.
Recently a specific genetic abnormality, called a ‘mutation’ has been found in at least eight out of 10 children with Dravet syndrome. This mutation is known as the ‘SCN1A’ mutation. The mutation can be looked for in a simple blood test. The discovery of this mutation has been very helpful in making or confirming a diagnosis of this epilepsy syndrome.
Dravet syndrome is one of the epilepsy syndromes that are most resistant to epilepsy medicines. Sodium valproate (Epilim) and lamotrigine (Lamictal) are usually tried first. However, lamotrigine makes the myoclonic seizures worse in many children. Other medicines which are helpful include clobazam (Frisium) and stiripentol (Diacomit).
Many children with Dravet syndrome seem to respond best to a specific combination of sodium valproate, stiripentol and clobazam. It is very important that only specialist epilepsy doctors, called paediatric neurologists, prescribe this combination of medicines. Other treatments which might be helpful include topiramate (Topamax), clonazepam (Rivotril) and zonisamide (Zonegram). A short course of a steroid (called prednisolone) and the ketogenic diet may also be helpful.
Children with Dravet syndrome may have seizures that go on for a long time and where an ambulance should be called. The children will need to be prescribed emergency or ‘rescue’ medicine to be given at home before the ambulance arrives.
Because children with Dravet syndrome always have learning disabilities they will also need full educational assessment and support.
The seizures continue to be very difficult to control, throughout childhood. Learning disabilities persist and are usually severe. As the condition progresses most children become unsteady on their feet (ataxic). Children with Dravet syndrome will need to be cared for throughout their lives. Usually by the age of 14 or 16 years, the seizures tend to become less frequent.
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Epilepsy Action would like to thank:
- Dr Richard Appleton, and Dr Rachel Kneen, consultant paediatric neurologists at Alder Hey Children’s Hospital, Liverpool, UK and
- Dr Stewart Macleod, consultant paediatric neurologist at Royal Hospital for Sick Children, Glasgow, UK.
They have kindly prepared the information on this page. It is based on their own research, experience and expertise.