Dravet syndrome, also known as severe myoclonic epilepsy of infancy (SMEI), is an uncommon form of epilepsy that starts in babies or young children. Children with Dravet syndrome have frequent, hard-to-control seizures and often face challenges with learning and development. The condition can also affect movement, behavior, and general health. Dravet syndrome lasts a lifetime, and seizures can be hard to control. While there is no cure, several treatments are available that can help reduce the frequency and severity of seizures and support a better quality of life for people and families living with this condition.

Dravet syndrome is a genetic form of epilepsy that begins in infancy, often between 5 and 12 months of age. Before seizures start, children with Dravet syndrome typically develop normally. Dravet syndrome belongs to a group of severe epilepsy conditions called developmental and epileptic encephalopathies. These are conditions in which ongoing seizures and abnormal brain activity cause delays in development and other problems.

Children with Dravet syndrome can have several types of seizures. These include tonic-clonic seizures (sometimes called grand mal seizures), which cause loss of consciousness and shaking of the whole body. They may also have hemiclonic seizures, in which the jerking affects only one side of the body. Seizures are often prolonged and may be triggered by fever, heat, or excitement. As children grow, they may develop other seizure types, movement difficulties, and problems with learning and behavior. Dravet syndrome is rare, affecting only about 1 to 6 people out of every 100,000. Both boys and girls can have Dravet syndrome. Dravet syndrome is lifelong, and symptoms and seizure types may change as a person ages.

Dravet syndrome is most often due to changes in the SCN1A gene. This gene helps the brain make proteins that allow brain cells to communicate properly. When this gene does not work as it should, the normal balance of electrical activity in the brain is disrupted, leading to seizures and other symptoms.

Most children with Dravet syndrome have a new change in the SCN1A gene that they did not inherit from either parent. In some cases, the gene change can be passed down from a parent who may have mild symptoms or no symptoms at all.

Sometimes, Dravet syndrome can be caused by changes in a different gene. The severity of symptoms can vary, even among people with the same gene change.

The main risk factors for Dravet syndrome are related to genetics and family history. Risk factors include:

• Having a parent who carries a changed SCN1A gene (or other gene changes), even if that parent has mild or no symptoms
• Having a family history of epilepsy or febrile seizures (seizures with fever)

Dravet syndrome causes several kinds of seizures and can lead to challenges with learning, movement, and behavior. Symptoms often start in the first year of life and can change as the child grows. Common symptoms include:

• Seizures that are often prolonged and difficult to control, sometimes triggered by fever, excitement, or other factors
• Tonic-clonic seizures, which involve loss of consciousness and shaking of the whole body
• Hemiclonic seizures, which cause jerking on one side of the body
• Myoclonic seizures, which are brief muscle jerks
• Absence seizures, which are short staring spells
• Status epilepticus, a prolonged seizure that does not stop on its own and requires emergency medical care
• Developmental delays, including slower learning, speech, or movement
• Intellectual disability, which can range from mild to severe
• Features of autism, such as difficulty with social interaction or communication
• Features of attention deficit hyperactivity disorder (ADHD), such as hyperactivity, impulsivity, or difficulty concentrating
• Movement and balance problems, such as unsteady walking or tremors
• Sleep problems, such as frequent waking or trouble falling asleep
• Feeding difficulties or slow weight gain
• Sensory processing difficulties, such as trouble with lights, sounds, or touch
• Problems with the body’s autonomic functions, such as heart rate, breathing, and temperature regulation

Diagnosis of Dravet syndrome involves a careful review of the person’s medical history, symptoms, and a physical and neurological exam. Doctors look for patterns of seizures that start in infancy, especially if they are prolonged, hard to control, and associated with developmental delays.

Doctors will ask about the age when seizures started, what triggers the seizures, and whether there is a family history of epilepsy or febrile seizures. They will also check for signs of developmental delays, movement problems, or behavioral changes.

Several tests can help confirm the diagnosis or rule out other conditions:

• Electroencephalogram (EEG): This test records the brain’s electrical signals to find patterns that may show epilepsy.
• Magnetic resonance imaging (MRI) scan: This scan uses magnets and radio waves to make detailed images of the brain and look for any structural issues.
• Genetic testing: This test checks for changes in the SCN1A gene or other genes known to cause Dravet syndrome. Finding a change can confirm the diagnosis and help guide treatment. (If no gene change is found but symptoms fit Dravet syndrome, doctors may still make the diagnosis based on clinical features.)
• Other laboratory tests: Additional tests may be used to rule out metabolic or infectious causes of seizures.

Treatment for Dravet syndrome focuses on reducing the number and severity of seizures, preventing emergencies, and supporting development and quality of life.

Treatments include:

• Anti-seizure medicines: Several drugs, including valproic acid, clobazam, stiripentol, fenfluramine, cannabidiol, and topiramate, may help control seizures. The choice depends on age, seizure type, and side effects.
• Ketogenic diet: This high-fat, low-carbohydrate eating plan may help reduce seizures and should be managed by doctors and dietitians.
• Epilepsy surgical options: There are some epilepsy surgeries that may help certain patients with Dravet syndrome, including vagus nerve stimulation (VNS).
• Physical, occupational, and speech therapy: These treatments help with movement, everyday tasks, and talking skills.
• Behavioral and educational support: Counseling, special teaching, and family support can help address behavior and learning issues.
• Emergency seizure plan: Families need a clear plan for seizure emergencies, including when to use rescue medicines (like benzodiazepines, which calm seizures) and when to call for help.
• Avoiding seizure triggers: Controlling fever, staying cool, and reducing exposure to flashing lights or patterns may lower seizure chances.
• Monitoring and follow-up: Regular visits with a child neurologist and other specialists allow doctors to monitor the condition and update treatments as needed.

Some medicines, such as carbamazepine, oxcarbazepine, phenytoin, and lamotrigine, can make seizures worse in Dravet syndrome and should generally be avoided. New treatments, including gene-based therapies, are being studied in clinical trials.

Complications of Dravet syndrome can affect many areas of health and daily life. The most serious complications include:

• Injury from falls or accidents during seizures.
• Status epilepticus, which means a long or repeated seizure that does not stop on its own and needs emergency care.
• Sudden unexpected death in epilepsy (SUDEP), which means a person with epilepsy may die suddenly without warning.
• Developmental delays and intellectual disability, which can affect learning, communication, and independence.
• Movement problems, such as unsteady walking, crouched gait, or tremors, which may get worse with age.
• Behavioral and psychiatric issues, including anxiety, attention problems, or features of autism.
• Sleep disturbances, such as frequent awakenings or insomnia.
• Problems with growth, nutrition, or feeding, which may require special support.
• Skeletal problems, such as curvature of the spine (scoliosis) or foot deformities, often in adolescence.

The outlook for people with Dravet syndrome depends on how severe the seizures are, how well treatments work, and whether there are other health problems. People with Dravet syndrome need ongoing care for this lifelong condition. Seizures often become less frequent with age, but problems with movement, learning, and behavior may continue or get worse over time.

Many people with Dravet syndrome live into adulthood, but there is a higher risk of early death, mainly due to status epilepticus or SUDEP. Early diagnosis, careful management, and support from a team of specialists can help improve quality of life for many people with Dravet syndrome. Research and new therapies continue to offer hope for better outcomes in the future.

“The Yale Pediatric Epilepsy team provides customized treatment plans for many children with Dravet syndrome,” says Yale Medicine pediatric neurologist Vinita Knight, MD. “We carefully consider a patient’s severity of seizures and comorbid conditions, along with the family’s priorities, to craft a tailor-made treatment plan that provides the patient with the best quality of life possible.”