Nonconvulsive status epilepticus in childhood localization-related epilepsy

Purpose: To report on three children with localization-related epilepsy who exhibited minor seizures (atypical absences, brief atonic, and myoclonic) and nonconvulsive status epilepticus (NCSE) consisting of these minor seizu res, and to elucidate their significance. Methods: We studied the electroclinical characteristics of these children. Ictal electroencephalograms (EEGs) of NCSE were evaluated by using simultan eous video-EEG-electromyogram (EMG) polygraphic recordings. Results: All patients began to have partial seizures between the ages of 6 months and 2 years 7 months, with minor seizures appearing later, between t he ages of 1 year 11 months and 6 years 6 months. These minor seizures evol ved into NCSE. Complex partial seizures remained after suppression of the m inor seizures. Interictal EEGs taken when the minor seizures appeared showe d excessive diffuse epileptic discharges in addition to multifocal spike-wa ves. Before and after suppression of the minor seizures, focal epileptic di scharges predominated on the EEGs. On ictal EEGs of brief atonic and myoclo nic seizures, diffuse spike-wave and polyspike-wave bursts were detected. I ctal EEGs of the atypical absences revealed diffuse spike-wave bursts mixed with irregular high-voltage slow waves, often interspersed with brief aton ic and myoclonic seizures. When atypical absences lasted for a long time, p atients manifested NCSE. Polytherapy might be related to the occurrence of minor seizures and NCSE, because all patients were treated with polytherapy at their appearance, and simplification of antiepileptic drug (AED) therap y seemed to be effective. Conclusions: We concluded that this NCSE is a type of atypical absence stat us which is an age-dependent, transient, electroclinical condition. The mec hanism of occurrence of these minor seizures might be related to secondary bilateral synchrony.