[Severe myoclonic epilepsy in infancy. Clinical and paraclinical aspects]

Severe myoclonic epilepsy in infancy (SMEI), or Dravet s syndrome, is one of the most serious forms of epilepsy in infancy. In this study we analyse the clinical characteristics of the process.

The cases reported in the literature are surveyed, together with a personal casuistic, from both a clinical and paraclinical point of view, and we assess the form of onset and the clinical, EEG and neuroimaging manifestations at different ages.

In most cases the disorder is characterised by onset during the first year of life, with febrile seizures, normal development prior to the onset of the seizures, multivariate critical phenomenology throughout the progression, early resistance to treatment, initial normality of EEG results and progressive neurological deterioration with ataxia and long tract signs.

The diagnosis of SMEI depends on the combination of clinical manifestations and EEG at different ages, and the presence of myoclonic seizures constitutes the most significant fact. The lack of strict diagnostic criteria allows for the existence of cases that are not perfectly identified. A percentage of cases exist that do not fulfil all the abovementioned criteria. The recent description of a mutation in the alpha subunit of a neuronal voltage dependent sodium channel (SCN1A) in chromosome 2q24, as the likely source of the process, will allow screening to be carried out in the early phases of the disorder. It will also allow studies to be conducted on the phenotype genotype correlation of the disease.