Dravet syndrome is a rare and severe form of early onset epileptic syndrome beginning in infancy characterized by refractory seizures and neurological development disorders. The first seizure occurs in the first year of life (usually at 5-8 months of age) in a normal developing child (Dravet et al. 2011).

Dravet Syndrome was first described in 1978 as « Severe Myoclonic Epilepsy in Infancy » (SMEI) by Dr Charlotte DRAVET but has been recognized throughout the world since then.

The first description of the clinical picture was :

  • Seizures appeared before the age of one year in an otherwise normally developing infant
  • The first seizures were convulsions (
    clonicMore or less rapid jerky movements, repeated at more or less regular intervals.
    tonic-clonicSeizures during which a tonic phase is succeeded by a clonic phase, with loss of consciousness, still known as 'grand mal'.
    ) associated with fever. These seizures were often long or very long (in some cases, more than one hour) and required emergency treatment (rectal or intravenous injection of an anti-convulsive drug).
  • Between the age of 2 and 3 years, other types of seizures developed (
    myoclonic seizuresSudden, very brief movements, sometimes repeated, similar to "jumping" (the physical reaction to being startled).
    atypical absencesAbsence is a brief loss of consciousness for a few seconds, characteristic of a type of general seizure without convulsion. Atypical absences are absences difficult to recognise because they start and end gradually.
    partial (focal) seizuresSeizures involving only a limited area of the brain.
    accompanied by developmental regression or stagnation with behaviour disorders. The brain
    CT scan Computed Tomography
    remained normal.

Because all of these clinical signs were not present in every patient, the criteria were enlarged and in 2001, the International League Against Epilepsy changed the epilepsy syndrome name from “SMEI” to “Dravet syndrome”.

The exact frequency in the general population is unknown. In 1990 it was estimated that Dravet syndrome occurred between 1/20,000 and 1/40,000 births. This frequency was probably an underestimate because the disease was not well known at that time.

Dravet syndrome seems to affect an equal number of boys and girls and no geographic region has a particularly high or low number of cases.