Typical absence seizures associated with localization-related epilepsy: a clinical and electroencephalographic characterization

INTRODUCTION: This paper describes the characteristics of patients with typical absence seizures associated with localization related epilepsy (LRE) and compares electroclinical features of absences occurring in these patients with those having childhood absence epilepsy (CAE). METHODS: Consecutive patients presenting with both LRE and typical absences in their epilepsy history were included in the study (Group 1). Clinical assessments and EEG investigations were conducted during the follow-up. Patients observed during the same period, but with typical absences fulfilling the CAE diagnostic criteria, were assigned to a second group (Group 2). RESULTS: Fourteen patients were included in Group 1. These patients had a mean age at their last visit of 11.3 years (range 7.2-16.8), with a mean follow-up period of 6.8 years. In all patients LRE was the first type of seizure to occur at median age of 4.95+/-2.1 years (range 1.9-8.8). Typical absences appeared at median age of 7.5+/-2.5 years (range 4.5-12.5), and were well controlled by therapy. Ictal EEG and semiology features of typical absences did not show any distinctive features when compared to those of Group 2 represented by 53 patients affected by CAE. However, age at onset was significantly higher in Group 1, as was the number of patients who underwent polytherapy, and the number with relapses after drug discontinuation. None of patients in Group 1 showed terminal remission. CONCLUSION: Although clinically heterogeneous and rare, the association of LRE with typical absences may be more than coincidental. In these patients, typical absences responded well to therapy, but terminal remission rates were lower than for CAE patients.