This is a neurodevelopmental disorder beginning in the infancy that presents a lifelong form of epilepsy. Most of the children affected with this condition have persistent, prolonged seizures and also present developmental disability. The case is variable between each individual and begins within the first year of the child’s life. The prevalence of this rare disorder is estimated to range from 1:20,000 to 1:40,000 infants. The medical treatment for this syndrome appears to be complicated as most medications don’t seem to have effective control of the seizures.
Causes
It is estimated that around 79% of the cases occur as the result of the mutation in the SCN1A gene. There are more than 400 SCN1A mutations have been identified but the severity of this syndrome is not well correlated with the type or the location of the mutation. The SCN1A gene provides instruction for the production of proteins that monitor the function of sodium ion channels. The genetic mutation results in the abnormality of the functions of the sodium ion channels in the brain which is believed to be the cause of seizures. Among most of the cases of dravet syndrome, the genetic mutation appears to be ‘de novo’ or new and rarely appears to be inherited from the parents.
Symptoms
The seizures are different from one case to another but usually begin in the first year of the individual’s life. The seizures may occur with the fever that is tonic-clonic involving the entire body or can be single sided convulsions. The seizure that lasts longer than five minutes requires medical treatment. Additional types of seizures can occur later with the increase in frequency that may develop without the fever. The most common types of seizures include the myoclonic (single jerks) or atypical absence seizures (unresponsiveness and staring). They may present additional symptoms such as sleep disturbance, ataxia (unsteadiness) and problems with their behavior. These children are at increased risk of sudden unexplained death in epilepsy but have an 85% chance of survival into adulthood.
Diagnosis
This syndrome is usually detected around the 6 months of age when fever develops from vaccination. If the child develops seizures around the time of vaccination and continues to have another episode before the first year, the genetic testing for the mutation in the gene SCN1A is usually recommended.
Treatment
This mainly involves the antiepileptic medications to control seizures and mostly the condition persists regardless of the treatment. Various medications have been identified to be beneficial although some appear to have an aggravating effect. Parents should be informed about the treatment of fever and the management of prolonged seizures. An EEG monitoring may be necessary to assess if the individual is in non-convulsive status epilepticus. Developmental evaluation is essential to begin early implementation of therapies for the affected children. This can include occupational, speech, physical and social therapies.
References
http://www.dravet.org.uk/what-is-dravet-syndrome/
https://rarediseases.org/rare-diseases/dravet-syndrome-spectrum/
http://www.dravetfoundation.org/what-is-dravet-syndrome/
