Clinical and electroencephalographic characteristics of a cohort of patients with epilepsy and absence seizures

Abstract

BACKGROUND: Epileptic syndromes with absence seizures (AS) possess unique clinical and electroencephalographic (EEG) characteristics. In typical or atypical AS, ictal phenomenology may include various characteristics. Vídeo-EEG monitoring enables findings to be correlated with ictal phenomenology. OBJECTIVE: To evaluate the different AS in a cohort of patients with drug-resistant epilepsy (DRE) based on the International League against Epilepsy (ILAE)'s 2006 classification, to correlate with ictal phenomenology recorded and to apply the Panayiotopoulos criteria. METHOD: This study included patients with criteria of AS followed up at the Epilepsy Clinic. A dual, cross-sectional cohort study was carried out between 2005 and 2008. Patients receiving care in the Epilepsy Program of the HUCFF-UFRJ, who had been investigated by video-EEG and who presented clinical and EEG criteria for absence seizures, typical or atypical, according to the criteria defined by the ILAE, were included in the study, independent of age onset, the review of clinical history, age onset, family history, epilepsy onset and evolution, seizures phenomenology, antiepileptic drugs response and neuroimaging studies were used to classify the patients among the different epileptic syndrome associated to absence seizures. RESULTS: Typical absences were more frequent (71.4%) than atypical absences. Cases of juvenile absence epilepsy were the most frequent (19%) in this series, followed by childhood absence epilepsy (14.4%) and juvenile myoclonic epilepsy (4.8%). In 14 patients (66.67%), diagnosis was modified from focal epilepsy to primary generalized epilepsy. Clinical and EEG diagnosis of absence epilepsy resulted in a dramatic improvement in the control of seizures following modification of diagnosis and indication of an appropriate antiepileptic drug. CONCLUSION: Our results show that typical AS are more frequent than atypical. AS was successfully defined in 10 patients following application of Panayiotopoulos' criteria. The consequent change in diagnosis and therapy resulted in resolution of refractoriness in 9 patients. We concluded that in DRE, AS associated to unusual ictal phenomenology improve dramatically when diagnosed by video-EEG, permitting seizures to be controlled. Clinical and EEG evaluation confirm that myoclonus, automatisms and autonomic disorders are involved and that the consciousness may be affected to different degrees.