The characteristics of epilepsy in a largely untreated population in rural Ecuador.

A house-to-house survey of epileptic seizures covering a population of 72,121 persons was carried out in a rural area of northern Ecuador. A cascade system of diagnosis was used to identify all cases of epileptic seizures in this population. 1029 cases were found, of whom 881 were considered to be definite cases and 148 were possible cases. Of the 1029 cases, 56% had active epilepsy. The lifetime prevalence rate was found to lie between 12.2 and 19.5/1000 and the prevalence of active cases between 6.7 and 8.0/1000. An annual incidence rate of between 122/100,000 and 190/100,000 was estimated. Seizure type was classified without EEG data and almost half of the cases had partial seizures. In 27% of cases an aetiology was proposed on clinical grounds. This is one of few reported studies of a population that has been largely unexposed to antiepileptic drugs, providing an opportunity to study the natural history of the untreated condition. It has been suggested that treatment in newly developing epilepsy will prevent its development to a chronic condition. Only 37% of the 1029 cases had ever received antiepileptic drugs, and only 12% of the cases were taking them at the time of the survey. Despite this, a high rate of inactivity was observed, with 44% of all cases free of seizures. Nearly two thirds of the inactive cases identified had never received treatment with antiepileptic drugs. In a subgroup of untreated cases with an active condition, treatment with antiepileptic drugs was initiated and was highly effective even in cases with a long previous history. Thus the findings from this study suggest that the development of epilepsy resistant to therapy is not always associated with a long duration of untreated epilepsy.