[Refractory epilepsy: use of the new definition and related risk factors. A study in the Mexican population of a third-level centre].

INTRODUCTION: The International League against Epilepsy (ILAE) has recently proposed a consensus to define refractory epilepsy. PATIENTS AND METHODS: A retrospective, analytical, descriptive study was conducted involving 206 patients who were attended at the epilepsy clinic of a third-level centre in Mexico. The ILAE's new definition of pharmacoresistance was used to classify the patients. The frequency and risk factors involved in the refractoriness were reported. The tendency to prescribe antiepileptic drugs (AED) in this population was analysed using secondary data.
RESULTS: Of the 206 patients analysed, 57 (28%) were free of seizures, 115 (56%) continued to have seizures, 17 (8%) were classified as undetermined and 17 (8%) were pseudo-refractory. The statistically significant factors associated to pharmaco-resistance that were found in our population were: focal versus generalised epilepsy (p = 0.02), catamenial epilepsy (p = 0.02), abnormal psychomotor development (p = 0.02), history of epilepsy in the family (p = 0.025), neurological examination with focal abnormality (p = 0.04), perinatal hypoxia (p = 0.06) and prior psychiatric illness (p = 0.03). The mostly frequently AED used in mono- and polytherapy were valproate and carbamazepine. Of all the patients who were free of seizures, 47% were treated using monotherapy.
CONCLUSIONS: The frequency of pharmacoresistance in the population analysed was estimated to be 56%. Identification of the factors associated with pharmacoresistance makes it possible to consider surgical treatment or to optimise the treatment with AED. There is a tendency to use the new AED, above all in combination therapy. Our findings are consistent with those described in the literature.