Dravet syndrome is one of the most severe epilepsy syndromes of early childhood, 
and it comes with very high morbidity and mortality. The typical presentation is 
characterized by hemiclonic or generalized clonic seizures triggered by fever 
during the first year of life, followed by myoclonic, absence, focal and 
generalized tonic-clonic seizures. Non-convulsive status epilepticus and 
epileptic encephalopathy are common. Development is normal in the first year of 
life, but most individuals eventually suffer from intellectual impairment. 
Dravet syndrome is associated with mutations in the sodium channel alpha1 
subunit gene (SCN1A) in 70-80% of individuals. SCN1A mutation results in 
inhibition of the GABAergic inhibitory interneurons, leading to excessive 
neuronal excitation. The "interneuron hypothesis" is the current most accepted 
pathophysiological mechanism of Dravet syndrome. The mortality rate is increased 
significantly in Dravet syndrome. Ataxia, a characteristic crouched gait and 
Parkinson's symptoms may develop in some individuals. It is likely that Dravet 
syndrome is underdiagnosed in adults with treatment-resistant epilepsy. Early 
diagnosis is important to avoid anti-seizure medications that exacerbate 
seizures.