Epilepsia mioclónica grave de la infancia (síndrome de Dravet). Ubicación nosológica y aspectos terapéuticos

AIMS: Severe myoclonic epilepsy in infancy (SMEI) is an epileptic syndrome recognised by the ICE of 1985 and 1989 and in the proposal put forward by the ILAE Task Force on Classification and Terminology in 2001. In this paper, its historical development, nosological characteristics and treatment are described. DEVELOPMENT: Although identified by Dravet in 1978, it has been called severe myoclonic epilepsy in infancy since 1981. As an alternative the name polymorphic epilepsy has also been put forward and in 2001 the ILAE recognised the eponym Dravet's syndrome. We describe how it may be mistaken for febrile convulsions in the early stages and later for Lennox Gastaut syndrome, Doose's myoclonic astatic epilepsy and certain progressive myoclonic epilepsies. We outline the risk factors, recognised in 1992, that facilitate an early diagnosis and the defining clinical criteria established in 1984. We point out the existence of atypical forms due to the absence of some of the defining criteria, which will never be above one, to formulate a diagnosis of SMEI. The frequency with which a family background of febrile convulsions and epilepsy appears seems to point to a genetic origin. Recently, de novo mutations have been found in the alpha subunit of the voltage dependent sodium channel as well as mutations in the gamma subunit of the GABAA receptor. Nosologically, it is located in group 3 of the 1989 ICE, which corresponds to epileptic syndromes without a focal determination, or which are generalised, and on the list of epilepsy/syndromes that was presented in 2001. SMEI is an epilepsy syndrome which is, in most cases, resistant to classical and new AED, and other more unusual treatment. The drugs that have proved to be more effective, although only relatively so, are topiramate, valproate and the benzodiazepines. At present another alternative that has appeared is stiripentol. Intravenous use of immunoglobulins can be useful. CONCLUSIONS: Dravet's syndrome, admitted as such by the ILAE in 2001 and probably caused by de novo mutations in the sodium channels or in the GABAA receptors, is one of the severest forms of epilepsy in infancy with very little or no response to current antiepileptic drugs. Those that have been seen to be most effective are topiramate, the benzodiazepines, valproate and, more recently, stiripentol.