Dravet syndrome

Who gets Dravet syndrome?

Dravet syndrome is a rare epilepsy syndrome. It affects around 1 in 15,000 children in the UK. It usually starts in the first year of life, often around six months. Babies usually show normal development before they start getting seizures associated with Dravet syndrome.

At least 8 out of 10 children with Dravet syndrome have a change (called a ‘mutation’) in a particular gene called the SCN1A gene. Most of the time, these are new changes that appear for the first time, rather than being passed down from a parent. Less often, there may be changes affecting other genes and this can sometimes make the diagnosis difficult.

Up to half of children with Dravet syndrome have a family history of febrile seizures (seizures associated with a high temperature) or other types of epilepsy. Sometimes this may be part of a syndrome called Genetic epilepsy with febrile seizure plus (GEFS+), which affects several members of the same family.

Symptoms of Dravet syndrome

Dravet syndrome usually starts with seizures similar to febrile seizures. It can be hard to tell whether a child has Dravet syndrome or just simple, febrile seizures at first. The more typical features of Dravet syndrome usually become more obvious during the child’s second year of life.

When children with Dravet syndrome first start to have seizures, they usually:

• Are linked to a high temperature. This could be due to a fever or high outside temperatures
• Involve just one side of the body
• May cause stiffness and jerking (a tonic-clonic seizure), or just repeated jerking (a clonic seizure) on one or both sides of the body
• Last a long time – often more than 20 minutes

Seizures that last a long time can be a serious situation called status epilepticus. This is when a seizure lasts longer than five minutes, or several seizures happen one after another without the person regaining consciousness.

Non-convulsive status epilepticus can happen when a non-convulsive seizure (without jerking), such as an absence or focal seizure, lasts too long. These can be harder to spot because the signs and symptoms can be less obvious. Your child might be confused and less responsive than usual, or have changes to their speech or behaviour for no clear reason.

Both types of status epilepticus can be dangerous and might need emergency treatment. Your specialist will talk to you about your child’s risk and make a care plan with you.

Between the ages of 1 and 5, your child might develop other types of seizures. These can include:

• Tonic-clonic seizures– which cause stiffness and jerking movements, and loss of consciousness
• Myoclonic seizures– causing jerks of the head, arms or legs
• Focal seizures– these start in one area of the brain and affect movements or sensations
• Atypical absence seizures – where your child goes limp and ‘floppy’ and can’t respond normally

Seizures aren’t always linked to a high temperature. They may also be triggered by physical activity, excitement, flashing or flickering lights (photosensitive epilepsy) and rarely, certain patterns such as checked or striped materials.

Children with Dravet syndrome usually start to have problems with development and behaviour from the second year of life. Behaviour problems can include features of ADHD (attention deficit hyperactivity disorder) or autism spectrum disorder (ASD). Children often have delays with their speech and language development. Sometime children walk in a crouching position called ‘crouching gait’.

The NHS website has information on autism and ADHD that you may find helpful.

Diagnosing Dravet syndrome

Your child should be assessed by a specialist doctor called a paediatrician if they are having seizures. The first couple of seizures in Dravet syndrome can look like simple febrile seizures. But if your child has a lot of these seizures associated with high temperatures and each one lasts more than five or more minutes, it may suggest that they have Dravet syndrome.

Your child’s specialist will ask questions about your child’s seizures and their development, and take a detailed family history. It can be useful if you’re able to show the doctor a video of your child’s seizures.

Your child’s doctor may recommend a number of tests to confirm a diagnosis. These will include an EEG (electroencephalogram) to look at electrical activity in the brain. The EEG is usually normal early on in the condition, but may start to show abnormal activity from the age of 2. If your child is sensitive to flashing or flickering lights, this may show up on an EEG. This is called photosensitivity. Your child may also have an MRI brain scan. This will usually be normal.

Your child’s specialist will also recommend that they have a genetic test to check for genes that can be linked to with this syndrome. This is usually done with a simple blood test. The genetic test can be helpful in confirming a diagnosis of this epilepsy syndrome. But having a change in an affected gene doesn’t automatically mean someone has Dravet syndrome. And not having a change in a gene doesn’t rule it out.

Your child will also be referred to a specialist in children’s epilepsy called a paediatric neurologist. This is because your child’s seizures may be difficult to control and also because of any other problems they may have.

Treatment for Dravet syndrome

Treatment of Dravet syndrome is very difficult, as the seizures in this condition don’t respond very well to epilepsy medicines. But there are still treatment options available to help manage your child’s symptoms. The National Institute for Health and Care Excellence (NICE) has guidance for treating Dravet syndrome. NICE says children with Dravet syndrome should be seen by a paediatric neurologist.

Your specialist will usually try a medicine called sodium valproate first. Sodium valproate is not recommended for people who are able to get pregnant because it can harm an unborn baby if taken during pregnancy. It’s still usually tried first in Dravet syndrome because it’s thought to be the best available treatment.

If there’s a chance your child may have children when they are older, the specialist should explain the risks and benefits of taking sodium valproate. When they are old enough to get pregnant, they will make sure your child is using effective contraception if needed.

If sodium valproate on its own doesn’t work, your child’s specialist may try ‘triple-therapy’ with a combination of three medicines: stiripentol, clobazam and sodium valproate.

If ‘triple-therapy’ doesn’t work, other treatments your child’s doctor may suggest include:

• A combination of the medicines cannabidiol and clobazam, if your child is over 2 years old
• A medicine called fenfluramine, if your child is over 2 years old and their seizures haven’t been controlled with 2 or more medicines
• The ketogenic diet – a special low-carbohydrate diet, that can help some people with epilepsy
• The medicines levetiracetam and topiramate
• A medicine called potassium bromide, if all other options haven’t worked

If no other treatments have helped your child, vagus nerve stimulation (VNS) or deep brain stimulation may be an option. Your child’s doctor will talk to you about these options.

It’s unlikely that brain surgery would be effective for children with Dravet syndrome.  Your child’s doctor may refer them for assessment to see if they are suitable for epilepsy brain surgery if no other options have helped.

Emergency treatment for prolonged or repeated seizures

Your child is very likely to have prolonged or repeated seizures as part of Dravet syndrome, that can develop into status epilepticus. Your child’s paediatrician or paediatric neurologist will discuss a ‘rescue’ or emergency care plan to treat any prolonged or repeated seizures that may happen at home.

Outlook of Dravet syndrome

People with Dravet syndrome will usually need support and care throughout their life. Seizures in Dravet syndrome are likely to continue to be very difficult to control throughout childhood. By the time children become teenagers or young adults, their seizures may happen less often. The seizures may be shorter and more likely to happen during sleep.

Nearly all people with Dravet syndrome will have learning difficulties. These can range from mild to very severe. These tend to continue throughout life. Many children will also show some signs of autism. As the condition progresses, children also experience movement problems, with most becoming more unsteady on their feet (ataxia).

Sadly, children with Dravet syndrome seem to be at a higher risk of SUDEP (sudden unexpected death in epilepsy). SUDEP is more likely to happen to children under the age of 11, but it may happen in later childhood. Of course, this can feel extremely worrying, but it’s important to be aware of it and to discuss it with your child’s specialist. They may be able to suggest some ways you can reduce your child’s risk or be alert to any problems.

Caring for a child with Dravet syndrome can often come with a lot of challenges. It is important to remember that you are not alone in this diagnosis and there are many places you can get different types of support.

Dravet Syndrome UK is dedicated to improving the lives of people affected by Dravet syndrome, and Mencap supports anyone living with learning disabilities. Your child’s paediatrician or paediatric neurologist will be able to give you more advice about support available to you and your child.

Epilepsy Action also offers different types of support that you may find useful.

Support

Contact
Charity for families of disabled children.
Freephone helpline: 0808 808 3555
Email: info@contact.org.uk

Dravet Syndrome UK
Charity dedicated to improving the lives of people affected by Dravet Syndrome through support, education and medical research.
Phone: 01246 912 421
Email: info@dravet.org.uk

Mencap
Charity supporting anyone affected by a learning disability.
Freephone helpline: 0808 808 1111
Email: helpline@mencap.org.uk