Dravet syndrome is a rare and severely disabling type of epilepsy presenting in infancy, sometimes called a catastrophic epilepsy. It was first described in 1978 by Charlotte Dravet, a paediatric epilepsy specialist working in Marseille. Other names that have been used for the condition include Severe Myoclonic Epilepsy of Infancy and Severe Polymorphous Epilepsy of Infancy.
A ‘syndrome’ is a group of signs and symptoms that, when considered together, suggest a particular medical condition. An epilepsy syndrome is diagnosed from the combination of age of onset of seizures, the different types of seizures, how they change over time, findings on EEG tests and other features such as behaviour and learning. As such, epilepsy is just one part of Dravet syndrome; there are various other health conditions and symptoms, which are often found in children with the condition.
Dravet syndrome is rare with latest research showing it affects approximately 1 in 19,000 people. Normally, the first seizure takes place in the first year of life; three-quarters of these seizures accompany a high fever caused by an illness. Sometimes, if a child has a fever caused by immunisation, this might be associated with a seizure. At first, doctors may diagnose a one-off febrile convulsion (a ‘fit’ that a child might have associated with a very high fever). Febrile convulsions are fairly common and, while very alarming for parents, most children tend to have normal development and have only one or very few seizures restricted to early childhood. However, with Dravet syndrome, other seizures follow, increasing in severity.
Seizures in the first year of Dravet syndrome are often clonic (jerking movements), prolonged, and tend to affect one side of the body.
The child’s development during the first year of life is usually normal; after this first year, a range of seizures may appear including:
- Myoclonic seizures, single or multiple muscle jerks, which may involve one part of the body or the whole body
- Atypical absences (where the child will stare) with brief loss of awareness
- Focal seizures, which may involve loss of awareness
- Non-convulsive status where the child develops a groggy, poorly functional state
- Serial seizures or status epilepticus, a prolonged seizure or a cluster of shorter seizures with little or no recovery in between.
Patients with Dravet syndrome are particularly prone to status epilepticus, therefore swift medical intervention is essential to stop the seizure as soon as possible to reduce the risk of damage to the brain or breathing problems caused by a long seizure.
From the second year onwards, the child’s development slows down or regresses, sometimes severely. Features of autism and attention deficit hyperactivity disorder (ADHD) are common.
Dravet patients often experience mobility issues, in particular with regards to an unsteady gait called ataxia. Some patients are affected severely, whilst in others the problem may be less severe.