What is Dravet Syndrome Causes and Symptoms

What is Dravet Syndrome? Causes and Symptoms

What is Dravet syndrome?

What is Dravet syndrome

Dravet syndrome is a rare form of epilepsy that begins in a baby's first year. It often starts with a prolonged seizure (lasting more than five minutes) triggered by a high fever.

Children with Dravet syndrome experience various types and severities of seizures. They may also face other challenges, such as developmental delays, speech and language difficulties, and problems with balance and walking.

Previously, Dravet syndrome was referred to as severe myoclonic epilepsy of infancy, epilepsy with polymorphic seizures, and polymorphic epilepsy in infancy.

What does Dravet syndrome look like?

Seizures typically begin within the first year of your child's life, often initially occurring with a fever. Subsequent seizures can occur without a fever and may involve jerking movements on one side of the body.

Other characteristics of Dravet syndrome include:

  • Seizures lasting longer than five minutes.
  • Seizures occurring every few weeks during infancy and early childhood.
  • A variety of seizure types.

Other triggers for seizures include:

  • Infections and illnesses.
  • An increase in body temperature not caused by fever, such as from warm or hot bath water, high air temperature, or physical exertion.
  • Photosensitivity, such as from flashing lights or patterns.
  • Emotional stress or excitement.

Initial Signs - First Year of Life

Initial Signs of dravet syndrome

Dravet Syndrome typically begins with prolonged, recurrent epileptic seizures often triggered by a fever. These seizures usually start in the first year of life, with the average onset around 5 months, but they can occur between 1 and 15 months. Until the first seizures, brain development appears normal. During the first year, seizures are often tonic-clonic (stiffness and jerking) or clonic (jerking), and they may affect one side of the body (hemiclonic).

Febrile seizures (or febrile convulsions) are common in childhood and usually not linked to epilepsy. They are caused by a high or rapidly rising temperature, often due to illness or vaccination. The first indication of Dravet Syndrome might be a prolonged febrile seizure in early infancy, lasting more than ten minutes and sometimes over half an hour (known as status epilepticus). These extended seizures may require emergency treatment and intensive care.

Early Childhood

Early Childhood signs

In the second year of life, seizures become more frequent and persistent, occurring with or without a fever and at any time of day or night. Between the ages of one and four, various seizure types may develop, including:

  • Myoclonic seizures: multiple muscle jerks involving one part or the entire body.
  • Atypical absences: brief staring episodes with a loss of awareness (usually less than 20 seconds).
  • Focal seizures: previously known as partial seizures, may involve loss of awareness and automatic movements such as lip-smacking, wandering, or hand fumbling.
  • Non-convulsive status: a prolonged groggy, poorly functional state.

Symptoms and Causes

Symptoms and Causes

What are the symptoms of Dravet syndrome?

Symptoms of Dravet syndrome vary widely among children, ranging from mild to severe.

Common Seizure-Related Symptoms:

  • Various types of seizures, including atypical absence seizures, complex febrile seizures, epilepsia partialis continua, focal aware seizures, focal hemiclonic seizures, focal impaired awareness seizures, generalized clonic seizures, photosensitive myoclonic seizures, and photosensitive tonic-clonic seizures.
  • Sudden muscle jerking (myoclonus).
  • Long-lasting seizures (more than five minutes).
  • Frequent seizures.
  • Behavioral, intellectual, and developmental setbacks. Initially, children develop normally, but as seizures become more frequent, developmental progress slows compared to other children.

Other Symptoms:

  • Problems with balance and coordination, such as an unsteady or crouched walk.
  • Anxiety.
  • Autistic behavior.
  • Attention deficit hyperactivity disorder (ADHD).
  • Delayed language development and difficulty speaking (slurred or slowed speech).
  • Learning difficulties, behavioral issues, and emotional dysregulation.
  • Growth and nutrition problems.
  • Sleeping difficulties.
  • Trouble regulating body temperature, heart rate, and blood pressure (dysautonomia).

What causes Dravet syndrome?

Dravet syndrome is caused by a mutation in the SCN1A gene. About 80% of children with Dravet syndrome have this gene mutation. However, having the mutation alone isn't enough for a diagnosis, and not having it doesn't rule out the condition. There is a spectrum of disorders related to SCN1A gene mutations. Not all children with this mutation will develop Dravet syndrome. The mildest condition in this spectrum is familial hemiplegic migraine, while the most severe is Dravet syndrome.

How is Dravet Syndrome Diagnosed?

How is Dravet Syndrome Diagnosed

To diagnose Dravet syndrome, your child’s healthcare provider will ask about their medical and medication history. Diagnosis can sometimes be delayed because MRI and EEG results are usually normal at first.

The healthcare provider will conduct a clinical exam to check for symptoms of Dravet syndrome. They will ask specific questions, including:

  • Did your child have normal or near-normal mental and physical/muscle development before the seizures started?
  • Did your child have two or more seizures, with or without fever, before the age of one?
  • Did two or more seizures last longer than five minutes?

You will also be asked to describe the types of seizures your child has had, what medications were prescribed (if any), and how well these medications controlled the seizures.

They might suggest a blood test to check for the SCN1A gene mutation, but they can often diagnose Dravet syndrome based on your child’s symptoms.

What’s the Prognosis if My Child Has Dravet Syndrome?

What’s the Prognosis if My Child Has Dravet Syndrome

Your child may experience long-lasting and frequent seizures. The aim of treatment is to achieve the best possible seizure control. Medications can help reduce the number and severity of seizures, but complete seizure freedom is usually not achievable.

Your child will also face other health issues and developmental delays that need early identification and management. As they grow older, particularly into their teen years and beyond, they may develop a crouched gait (unsteady walk/balance). Mental decline tends to slow and stabilize with age, and seizures often decrease in number and duration. Despite this, most individuals with Dravet syndrome will require ongoing care from parents or caregivers throughout their lives.

Is There a Cure for Dravet Syndrome?

Currently, there is no cure for Dravet syndrome, but research is ongoing.

What’s the Life Expectancy for a Child with Dravet Syndrome?

What’s the Life Expectancy for a Child with Dravet Syndrome

Approximately 15% to 20% of individuals with Dravet syndrome do not reach adulthood. Up to 20% of those with the condition may die from sudden unexpected death in epilepsy (SUDEP), prolonged seizures, or seizure-related accidents and injuries such as drowning and infections.


Receiving a diagnosis of Dravet syndrome is challenging. However, researchers have identified that the syndrome is often caused by a defect in the SCN1A gene, and they are working towards better treatments and, hopefully, a cure. Currently, three new medications have been approved specifically for Dravet syndrome. While controlling seizures in Dravet syndrome is difficult, these new medications, along with established ones and other therapies, can help reduce the number and severity of seizures. Your child will need lifelong care. Besides the medical support from your healthcare team, connecting with other families who have children with Dravet syndrome can be very helpful. Ask your child’s healthcare provider for recommendations on local support groups.

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