Dravet syndrome

What is Dravet syndrome?

Dravet syndrome is a severe type of epilepsy that begins in infancy and is associated with seizures that are difficult to treat and significant neurodevelopmental impairments. Dravet syndrome is a rare disease. It is estimated to affect 1 in 15,700 people. Most children with Dravet syndrome have a mutation in the sodium channel gene SCN1A.

Children with Dravet syndrome have a wide range of seizure types. They also have many other symptoms, including developmental delays, autistic features, speech and language problems and balance and walking issues.

What are the symptoms of Dravet syndrome?

Children with Dravet syndrome present with seizures with fever in the first two to three months of life. These are prolonged and usually affect one half of the body. These children continue to have similar seizures with fever and later develop seizures without fever as well. In the second year of life, children with Dravet syndrome typically have developmental delays and language issues. Their seizures continue to be triggered by fever and infectious illnesses.

Your child may have multiple types of seizures, such as hemiclonic (seizures on only one side of the body), focal, myoclonic, generalized tonic clonic, atypical absence and atonic seizures. In addition, affected children may also have the following features:

• Developmental delay
• Autistic features
• Behaviour issues (such as aggression)
• Speech delay
• Balance and coordination issues
• Movement disorders such as dystonia
• Abnormal gait (crouch gait)
• Sleep problems
• Difficulty in temperature regulation
• Low muscle tone
• Growth problems

What causes Dravet syndrome?

A genetic variant (mutation) of the SCN1A gene is the most common cause of Dravet syndrome. Rarely, other genetic variants may be the cause.

Is Dravet syndrome inherited?

In most children, Dravet syndrome occurs because of a de novo variant. This means there is a new variant in the child, and parents do not carry the abnormal variant. Rarely, it may be an inherited condition (passed down in families through genes) in which several family members are affected.

How is Dravet syndrome diagnosed?

Neurologists diagnose Dravet syndrome by talking with you and your child about your child’s history, MRI of the brain, which is usually normal, and genetic testing to confirm diagnosis. Your child may also have EEGs. EEGs are usually normal at the beginning of the illness.

How is Dravet syndrome treated?

The treatment of Dravet syndrome is multi-disciplinary. This means many types of health-care providers will be involved in your child’s care:

• Neurologists treat the seizures and movement disorders.
• Developmental pediatricians manage developmental aspects such as global developmental delay and autism spectrum disorder.
• Children may also require educational support, physiotherapy, occupational therapy and speech therapy.
• Psychiatric and psychological support may be needed for challenging behaviours.

Anti-seizure medications

Seizures are a major concern in children with Dravet syndrome. Treatment is started with anti-seizure medications, usually valproate. Other drugs that may be tried include clobazam, topiramate and levetiracetam. Some anti-seizure medications may be beneficial in children who do not respond to the first- and second-line medications. These include stiripentol, cannabidiol (medical marijuana) and fenfluramine. Certain anti-seizure medications can worsen seizures in children with Dravet syndrome, so they must be avoided. These include phenytoin, carbamazepine and oxcarbazepine.

The ketogenic diet

The ketogenic diet may help reduce seizures in children with Dravet syndrome. Your child’s neurologist may recommend it if seizures continue after trying two or three anti-seizure medications.

Rescue medications

As children with Dravet syndrome are at risk of status epilepticus, your child’s neurologist will also prescribe rescue medications to try to stop seizures.

What are the severe complications of Dravet syndrome?

• Status epilepticus (prolonged seizures)
• Sudden unexplained death in epilepsy (SUDEP)

Dravet syndrome carries an increased risk of SUDEP. Your child’s neurologist will guide you on having a seizure action plan and will explain measures for preventing SUDEP.

What are the long-term outcomes for children with Dravet syndrome?

Dravet syndrome has significant long-term impacts on children, including ongoing seizures, developmental delays and behavioural problems.  Children with Dravet syndrome may develop difficulties with gait and movement, with some individuals experiencing a crouch gait pattern and difficulty walking long distances.  While seizure frequency and severity may decrease with age, Dravet syndrome is a lifelong condition with associated health challenges.

Resources

If you wish to learn more about Dravet syndrome, visit the following resources: 

• Dravet Syndrome Foundation: https://dravetfoundation.org
• Dravet Syndrome UK: https://www.dravet.org.uk