What Is Dravet Syndrome? Symptoms, Causes, Diagnosis, and Treatment

Dravet syndrome is a rare, severe form of epilepsy with symptoms that begin before a child turns 15 months old (and often within the first year of life). (1)

Formerly known as severe myoclonic epilepsy of infancy (SMEI), Dravet syndrome initially causes convulsive seizures but can present with different types.

Children with this neurological disorder typically develop normally within at least the first few years of life. But as their seizures increase, they may begin missing developmental milestones and have difficulties with eating, appetite, balance, and crouched gait (walking). Other symptoms may include loss of motor skills, intellectual disability, impaired speech, and issues with movement. (2)

Early signs and symptoms of Dravet syndrome include convulsive seizures that can be described as follows: (1)

• They are often prolonged in duration and involve half the body, which may be followed by seizures that affect the other side of the body. These initial seizures are commonly triggered by high temperatures (febrile seizures). (2) They may also be caused by temperature changes, such as getting out of the bath. (1)
• These early seizures, which usually happen every few weeks in infancy and early childhood, may be tonic-clonic (convulsive), or may feature clonic (jerking) movements on one side of the body. (3)
• They often last more than five minutes and can lead to status epilepticus (when seizures don’t stop or occur close together).

Other types of seizures that people with Dravet syndrome may experience include:

• Myoclonic Seizures These are brief jerks of a muscle or group of muscles, and typically begin when a child is between 1 and 5 years old.
• Atypical Absence Seizures With these seizures, a person may stare but may be able to respond somewhat. (4)
• Atonic Seizures With atonic seizures, a person suddenly loses muscle tone, which may cause their head or body to go limp. (5)
• Focal Onset Aware or Impaired Awareness Seizures These were previously called partial seizures. (6) In focal onset aware (sometimes simply called focal aware) seizures, the person stays alert and can interact with others. In focal onset impaired awareness seizures, the person is unaware of what is going on around them.
• Tonic Seizures In these seizures, the body, arms, or legs may all of a sudden become stiff or tense. (7) These usually happen during sleep and may begin in later childhood. (3)
• Nonconvulsive Status Epilepticus These are long or multiple absence or focal impaired awareness seizures, where the person is somewhat less responsive and the body twitches for prolonged periods of time. (3,8)

Seizures may be triggered by various factors, including fevers, infections, changes in body temperature, flashing lights, and emotional stress. (3)

Learn More About Signs and Symptoms of Dravet Syndrome

About 80 percent of people with Dravet syndrome have a specific mutation of the SCN1A gene that is directly responsible for the disorder (but not all SCN1A mutations cause Dravet syndrome). (3) SCN1A belongs to a family of genes involved in making sodium channels, which help brain cells function. (9) In most cases, this gene mutation is not inherited from parents (3). Instead, it is regarded as a de novo, or new mutation in the child.

In rare cases, atypical Dravet syndrome may be linked to other genetic mutations, such as SCN1B, GABRG2, or HCN1.

Diagnosis of Dravet syndrome is based on a clinical exam, medical history, and genetic testing. (2)

Seizures that last longer than 10 minutes, occur on one side of the body, and are caused by a warm water bath in children under 1 year old may indicate a Dravet syndrome diagnosis. (3)

A blood test can confirm the diagnosis. Even if the test does not reveal a gene mutation, Dravet syndrome may still be diagnosed based on symptoms.

A panel of 13 physicians and five family members of children with Dravet syndrome recommended new diagnostic criteria for the condition. (10) For infants and young children, the criteria include:

• Seizures that begin between 12 and 18 months old
• Recurrent tonic-clonic or hemi-convulsive seizures (those that affect only half the body)
• Myoclonic seizures that arise by age 2, followed by various other types of seizures
• Seizures triggered by hyperthermia (high body temperature) or other triggers, including flashing lights, bathing, and overexertion
• Normal results for developmental tests, neurological exams, MRIs, and EEG readings

Prognosis of Dravet Syndrome

As children with Dravet syndrome grow up, the decline in their cognitive abilities levels off. (1) However, most teenagers and adults with Dravet syndrome are dependent on their caregivers. This is due to the intellectual disability — ranging from mild to profound — that Dravet syndrome causes.

Seizures from Dravet syndrome typically lessen in frequency and duration as children get older, but gait abnormalities appear to get worse during adolescence.

People with Dravet syndrome face a 15 to 20 percent mortality rate due to a fatal complication called SUDEP (sudden unexpected death in epilepsy), prolonged seizures, seizure-related accidents like drowning, and infections. (11)

Dravet syndrome is a lifelong condition. (1)

The primary goal of treating Dravet syndrome is to reduce the frequency and duration of seizures. (2)

Treatment involves finding the best combination of medications to control seizures.

Medication Options

Doctors often prescribe anticonvulsant drugs like valproic acid and clobazam as first-line medication to control seizures, but they usually aren’t effective enough on their own.

In June 2018, the U.S. Food & Drug Administration (FDA) approved the first drug for the treatment of Dravet syndrome, which was also the first drug to contain cannabidiol to be approved: Epidiolex. (12) Cannabidiol, or CBD, is derived from marijuana but does not cause intoxication or euphoria (the high associated with marijuana).

One study on Epidolex showed a 47.6 percent mean reduction in seizures, while another found that Epidiolex is safe and effective for Dravet syndrome seizures at a broader range of doses than originally approved. (13)

In August 2018, the FDA approved a second drug for the treatment of Dravet syndrome seizures. The drug, stiripentol (Diacomit), is an anticonvulsant that is only indicated for Dravet syndrome patients who are at least 2 years old and are also taking clobazam. (14)

Another medication to treat Dravet syndrome (as well as Lennox-Gastaut syndrome, another epilepsy-related condition), fenfluramine (Fintepla), was approved in June 2020. (3)

Doctors sometimes prescribe other anticonvulsant drugs to control seizures caused by Dravet syndrome, such as levetiracetam (Spritam, Keppra), notes one survey. (15) Another drug, STK-001, is currently being tested for Dravet syndrome.

Conversely, people with Dravet syndrome should not use sodium channel blockers, as this could worsen symptoms. These drugs include carbamazepine (Tegretol), oxcarbazepine (Trileptal), and lamotrigine (Lamictal), among others. (16)

Alternative and Complementary Therapies

Research suggests that a ketogenic diet, which is high in fats and low in carbohydrates, may help people with Dravet syndrome control seizures. (17)

Vagus nerve stimulation, in which a device is implanted under the skin in the chest to prevent seizures by sending pulses of electrical energy to the brain via the vagus nerve, can also be helpful. (3,18)

Learn More About Treatment for Dravet Syndrome: Medication, Alternative and Complementary Therapies, and More

People with Dravet syndrome may lose developmental and cognitive skills. (2) They may also experience speech impairment and difficulty walking.

In adulthood, nighttime seizures may occur. More serious complications include status epilepticus and sudden death.

Up to 20 percent of people with Dravet syndrome die from either SUDEP (sudden unexpected death in epilepsy), prolonged seizures, seizure-related accidents like drowning, or infections. (11)

Other complications that can develop from Dravet Syndrome include:

• Chronic infections
• Disruptions in the autonomic nervous system, which can lead to problems with regulating body temperature, heart rate, blood pressure, and other issues
• Sleeping issues
• Growth and nutrition problems
• Orthopedic conditions
• Sensory integration disorders

Learn More About the Complications of Dravet Syndrome: How It Affects Your Body in the Short and Long Term

Reports suggest that 1 in 20,000 to 1 in 40,000 people have Dravet syndrome. (3) Three to 8 percent of children who have their first seizure by 12 months old may have Dravet syndrome.

One report found that the rate of Dravet syndrome in the United States may be much higher than previously thought. (19) By looking at a cohort of California births, the scientists estimated that 1 in 15,700 U.S. infants have Dravet syndrome.

Two other types of epilepsy are also caused by defects in the SCN1A gene: borderline SMEI (SMEB) and another type of infant-onset epilepsy called generalized epilepsy with febrile seizures plus (GEFS+). (1)

Children with Dravet syndrome may be misdiagnosed with other forms of epilepsy, such as: (16)

• Myoclonic atonic epilepsy
• Lennox-Gastaut syndrome
• Myoclonic epilepsy of infancy
• Genetic epilepsy with febrile seizures plus
• Atypical febrile seizures
• Mitochondrial disorders

The National Institute of Neurological Disorders and Stroke

The National Institute of Neurological Disorders and Stroke is an institute within the National Institutes of Health (part of the U.S. Department of Health and Human Services) that aims to understand the brain and nervous system and to reduce the burden of neurological disease. Their website has information about the treatment and prognosis of Dravet Syndrome.

Epilepsy Foundation

The Epilepsy Foundation is a national nonprofit that advocates on behalf of people with epilepsy and their caregivers and works to find therapies and cures to stop seizures and save lives. Their website has information about who gets Dravet Syndrome and what to do when a seizure happens.

Dravet Syndrome Foundation

Dravet Syndrome Foundation (DSF) aims to raise funds for Dravet syndrome and related epilepsies; support and fund research; increase awareness; and provide support to affected individuals and families. Their website has information about the diagnosis of Dravet Syndrome, genetic testing, and more.