Dravet syndrome, previously known as Severe Myoclonic Epilepsy of Infancy (SMEI), is a rare form of intractable epilepsy that begins in infancy and proceeds with accumulating morbidity that significantly impacts individuals throughout their lifetime. Dravet syndrome has an estimated incidence rate of 1:15,700 individuals, over 80% of whom have a mutation in their SCN1A gene.
Dravet syndrome is a Developmental and Epileptic Encephalopathy, or DEE, part of a group of severe epilepsies with frequent and difficult to treat seizures and significant developmental delays. Seizures in Dravet syndrome usually begin during the first 2-15 months of life, often in the presence of fever or warm temperatures. Seizures are frequently prolonged, and are not well managed with current medications. Patients present with a variety of seizure types that generally evolve with age. As with all DEEs, Dravet syndrome includes more than just difficult to control seizures. Other comorbidities such as developmental delay and abnormal EEGs often emerge during the second or third year of life. Common issues associated with Dravet syndrome include:
- Prolonged seizures
- Frequent seizures
- Behavioral and developmental delays
- Movement and balance issues
- Orthopedic conditions
- Delayed language and speech issues
- Growth and nutrition issues
- Sleeping difficulties
- Chronic infections
- Sensory integration disorders
Dysautonomia, or disruptions of the autonomic nervous system which can lead to difficulty regulating body temperature, heart rate, blood pressure, and other issues
Who Gets It?
Researchers estimate that between 1 in 15,700 and 1 in 40,000 infants born in the U.S. have Dravet syndrome. About 3% to 8% of children who have their first seizure by 12 months of age are likely to have Dravet syndrome.
How is it treated?
There is no cure for this condition. However, treatments may decrease the number and severity of seizures. Treatment options include:
Doctors usually prescribe anticonvulsants to people with Dravet syndrome. These decrease the severity and amount of seizures. Two of the most common medications for Dravet syndrome are valproic acid and clobazam. In 2018, the Food and Drug Administration (FDA) approved a new drug called Epidiolex, which contains cannabidiol, to treat seizures associated with Dravet syndrome.
Research suggests the ketogenic diet which is high in fat and low in carbohydrates, may help individuals with Dravet syndrome. The diet affects biochemical pathways involved in the functioning of the central nervous system. It also affects GABA levels.
- Avoiding triggers
Avoiding seizure triggers is important for people with Dravet syndrome. Hot baths, jacuzzis, and flashing lights can all bring on seizures.
- A vagus nerve stimulator (VNS)
People with Dravet syndrome may benefit from a vagus nerve stimulator. A doctor will perform surgery to insert a small electrical device in the person’s chest for this treatment. The device, which sends electrical impulses to the brain via the vagus nerve, may help reduce seizure frequency. The vagus nerve is involved in the function of the nervous system.
- Treatment for developmental delays
There are many treatments for developmental delays, but none are curative. The most common treatments are occupational and physical therapy.
What Is The Outlook?
The average life expectancy of people with Dravet syndrome is not clear, but estimates suggest that 10–20% of individuals with Dravet syndrome do not survive beyond the age of 10.
Sudden unexpected death in epilepsy (SUDEP) is the most common cause. For this reason, neurologists recommend that parents of infants with this condition adopt SUDEP risk reduction strategies such as seizure detection and baby monitoring devices.
The frequency of seizures in individuals with Dravet syndrome becomes less frequent as they reach adulthood, but they typically still have developmental and motor disabilities. Many adults with Dravet syndrome have caretakers to help with day-to-day activities.
As scientists come to understand this condition better, they continue to create improvements to current treatments. For example, Epidiolex, the first FDA-approved drug for Dravet syndrome, may reduce seizure frequency by up to 39%.