[Transional syndrome: from West to Lennox-Gastaut syndromes].

West syndrome or infantile spasms is an epileptic encephalopathy, classified as generalized epilepsies and syndromes. There are multiple reports of the evolution from West to Lennox-Gastaut syndrome of 25 up to 60%, without a specific cause is determined. It has been reported that they may be only an epileptic entity age dependent that it would be in relation to the degree of brain immaturity. In this retrospective review of 130 cases of West syndrome, only 14 (10.7%) evolved to Lennox-Gastaut. Having received in all cases vigabatrin as a treatment, makes us suppose that the low incidence could be related to the use of this drug. Given that vigabatrin has a gabaergic action and increased levels of ACTH, may explain this relationship but this must be confirmed with the best knowledge of the intimate mechanisms of these serious epileptic encephalopathies.