Recurrence after a First Unprovoked Cryptogenic/Idiopathic Seizure in Children: A Prospective Study from São Paulo, Brazil

Summary: Purpose: To evaluate the recurrence risk after a first unprovoked seizure in a large population of children and adolescents of a developing country. Methods: This prospective study was conducted at two tertiary hospitals, between September 1989 and August 1998. Children were enrolled if they had a first unprovoked cryptogenic/idiopathic seizure and maximal interval to the enrollment ≤90 days. EEG and computed tomography (CT) were performed in most patients. Potential predictors of recurrence were compared by using the Cox proportional hazards model in univariate and multivariate analyses. Survival analysis was performed by using the Kaplan–Meier curves. Results: Two hundred thirteen children were included. Recurrence occurred in 34% of the patients, and mean time for recurrence was 12 months. Statistical analysis showed significance for seizure recurrence only for patients with abnormal EEGs. CT was performed in 182 patients, and abnormalities were found in 9.5%. Small calcifications were the most frequent finding, and this was not a predictor for recurrence. Conclusions: The risk of recurrence after a first unprovoked seizure in children from a developing country is similar to that found in developed countries. An abnormal EEG is a risk factor for seizure recurrence in children with a cryptogenic/idiopathic seizure. Calcifications on CT do not increase the risk of recurrence.