What is Dravet syndrome?
Dravet syndrome, also known as severe myoclonic epilepsy of infancy (SMEI), is a rare form of epilepsy that begins in infancy. It is a debilitating, life-long condition that can severely impair the quality of life of the patient.
Patients experience frequent seizures, poor seizure control and developmental delays. Initial seizures are most often prolonged events when your child becomes feverish and in the second year of life other seizure types (often without fever) begin to emerge.
What causes Dravet syndrome?
While a diagnosis of Dravet syndrome is made clinically, up to 80% of cases will also test positive for an SCN1A gene mutation, helping to confirm the diagnosis. It is important to note that the absence of an SCN1A mutation does not exclude diagnosis.
How can my child get genetic testing?
Genetic testing is commercially available in most countries. Upon receiving a positive genetic test result, parents may also be tested to establish inheritance.
Who gets Dravet syndrome?
Dravet syndrome occurs randomly; even though it is a genetic disease, the mutations are most often new mutations affecting only the child with the syndrome. In other words, the gene mutation is not present in other family members.
What are the signs and symptoms of Dravet syndrome?
Signs and symptoms may include:
- Seizures accompanied by fevers in the first year of life
- Seizures of various types beginning after the first 12 months of life
- Episodes of status epilepticus (prolonged seizures)
- Seizures do not respond to standard anticonvulsant drugs
- Initial development is normal, then slows or stagnates in the second year of life
- Myoclonic seizures (brief shock-like jerks of a muscle or group of muscles) occur around the age 18 months of age
- Seizures associated with vaccinations, hot baths or warm temperatures
- Disruptions of the autonomic nervous system (which regulates things such as body temperature and sweating)
What tests are used to diagnose Dravet syndrome?
There are now commercially available blood tests which can screen for an SCN1A gene mutation that may be ordered by your doctor. However, current technology may not detect all mutations. Some screening labs also test for SCN2A, GABRG2 and PCDH19 mutations that may cause Dravet syndrome and related epilepsies. Consultation with a genetic counselor is available for families through some labs.
Why choose Children's Hospital Colorado for Dravet syndrome testing?
Children's Colorado follows the largest group of children with Dravet syndrome in the region; and therefore our providers have experience with this rare syndrome. We have compassionate use access to stiripentol (an anticonvulsant drug used in the treatment of epilepsy; approved for the treatment of Dravet syndrome, as well as participate in national trials for treatment of this rare disorder.
What to expect from Dravet syndrome testing
This is a simple blood test that can be drawn in the lab. The results can take up to three months to return.
How do providers at Children's Colorado make a diagnosis?
Dravet syndrome is diagnosed clinically based on seizure history, clinical aspects, neurologic examination, EEG pattern and observation. Subsequently, genetic testing of the SCN1A gene can confirm the diagnosis in the majority of cases. However, a mutated SCN1A gene cannot be identified in approximately 20% of the patients who meet the diagnostic criteria of the syndrome. Therefore, it is possible that other genes might be involved.
How is Dravet syndrome treated?
Because Dravet syndrome is a spectrum disorder, the course of the disease is variable from child to child and there is no standard treatment protocol. Multiple and changing seizure types are common and vary from patient to patient. EEG monitoring and neuroimaging techniques are often used to help further confirm diagnosis.
Anticonvulsants that have been shown to be useful for chronic seizure management in Dravet syndrome include benzodiazepines, topiramate and valproic acid. Stiripentol (Diacomit) has been shown to have efficacy in some Dravet patients when used in conjunction with other anticonvulsants, typically valproic acid and clobazam.
Anticonvulsants frequently used in treatment
- Clobazam (ONFI, Frisium, Urbanyl)
- Clonazepam (Klonopin, Rivotril)
- Levetiracetam (Keppra)
- Topiramate (Topamax)
- Valproic acid (Depakote, Depakene, Epilim, Epival)
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