Dravet Syndrome

Dravet syndrome is a rare but severe form of epilepsy that begins in infancy. The condition also used to be called severe myoclonic epilepsy of infancy or polymorphic epilepsy in infancy. Infants with Dravet syndrome have seizures that last for a long time and can happen often. These seizures can cause many developmental delays and other health problems.1,2

Who gets Dravet syndrome?

About 1 in every 15,700 people in the United States have Dravet syndrome. The exact number is unknown.1,2

What causes Dravet syndrome?

In most cases, Dravet syndrome is caused by a mutation (change) in the SCN1A gene. Sodium channels are proteins in the brain that help control the flow of electric signals. These signals are important for your brain to function. When the SCN1A gene is mutated, the sodium channels do not work correctly. This can cause problems with electric signaling in your brain, leading to seizures.1,2

Some SCN1A mutations are linked to less severe forms of epilepsy. So not all children with these mutations will get Dravet syndrome.1,2

Inheritance

There are different ways genetic information can be passed down from 1 generation to the next. Each method has its own set of rules.3

Dravet syndrome is passed down in some families in an autosomal dominant pattern. Autosomal means the gene mutation is on 1 of the chromosomes that do not determine the baby's sex. If 1 parent has the mutation, there is a 1 in 2 chance that the child will inherit it. That is because the mutated gene is "dominant" over the non-mutated gene.3

But in 9 out of 10 children with Dravet syndrome, the mutation is "de novo" or new to the family. In other words, it is not passed on from a parent.3

Symptoms

The first seizure usually occurs by age 1. Heat is a trigger in many children. The heat could be from a fever, hot bath, or being overheated. The baby's first seizure might be tonic-clonic (stiffening, loss of consciousness, jerking) or clonic (jerking only). Many times, the symptoms appear on 1 side of the body only.1,4

Infants with Dravet syndrome can also have other types of seizures, including:1,5-9

  • Myoclonic seizures – Quick, shock-like jerks
  • Atypical absence seizures – Absent stare (absence seizure) but can respond a little
  • Atonic seizures – Baby suddenly goes limp
  • Focal onset aware (simple partial) seizures – Infant is awake and alert but might have unusual muscle spasms, a blank stare, or head movements
  • Focal onset impaired awareness (complex partial) seizures – Unusual muscle spasms, a blank stare, or head movements but baby seems confused or impaired

The seizures in Dravet syndrome can often last more than 5 minutes, resulting in status epilepticus. Status epilepticus is a medical emergency. It requires rapid treatment in a hospital to prevent serious complications or even death.10

Seizure triggers

Children with Dravet syndrome may have different seizure triggers, including:1

Diagnosis

A correct diagnosis is critical in Dravet syndrome, as some anti-seizure drugs can worsen the condition. Your doctor will perform a complete history and order tests such as an electroencephalogram (EEG). An EEG is a painless test that measures the electrical activity of your baby’s brain.1,11

Genetic blood tests confirm the diagnosis of Dravet syndrome. Your doctor may also order different tests to rule out other conditions.1

Treatment for Dravet syndrome

Getting care at an epilepsy center is a priority. These centers have experts at a central location. This ensures the best care.1

Seizures from Dravet syndrome are hard to control. But, doctors will often prescribe 2 or more anti-seizure drugs to try to control them. Common drugs prescribed include:1

  • Valproic acid
  • Clobazam
  • Topiramate
  • Stiripentol
  • Fenfluramine
  • Cannabidiol

A diet that is very low in carbohydrates and high in fat (ketogenic or "keto" diet) helps some but not all people with seizures. A keto diet has risks. Talk to your doctor or nutritionist before starting a new diet.1

Problems linked to Dravet syndrome

Seizures are common and hard to manage. This often results in children with Dravet syndrome having developmental delays. Specific issues include:2

  • Seizures that last a long time
  • Seizures that occur often
  • Delayed development and behavior
  • Balance and movement problems
  • Bone and muscle problems
  • Delayed speech and language
  • Sleeping disorders
  • Chronic infections
  • Sensory problems
  • Problems regulating “automatic” body functions like:
    • Blood pressure
    • Temperature
    • Heart rate

Outcomes

While severity can vary, Dravet syndrome can negatively impact the entire family's quality of life. The constant care needed can be physically and emotionally draining for caregivers. While some treatment is available, the options are limited. Those with Dravet syndrome face a 15 to 20 percent death rate because of sudden unexpected death in epilepsy (SUDEP). More research is needed to provide a much-needed cure for this complex disease.2

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Written by: Katie Murphy │ Last reviewed: April 2022