Purpose: To better delineate the electroclinical features of infants who presented with focal seizures and typical midline sleep EEG abnormalities with a benign outcome. We discuss the significance of the typical EEG marker in non-epileptic patients.
Methods: Patients were selected from a group of epileptic subjects with seizure onset less than 3 years we observed from 1st November 1990 and 31st December 2003. Inclusion criteria were the presence of typical sleep EEG marker and focal seizures with benign outcome. Cases with less than 18 month follow-up period were excluded from this study.
Results: There were 19 patients (12 males, 7 females). Pre-, peri- and post-natal personal history was negative in all patients. Psychomotor development was normal, both before and after seizure onset. Neuroradiological investigations gave normal results. Seizure manifestations were typical, characterized by cyanosis, staring and rare lateralizing signs, of short duration. Age at onset was comprised between 4 and 30 months. The typical EEG marker, a spike followed by a bell-shaped slow-wave, localized in the midline regions, was present in all subjects only during sleep. All had a favorable outcome and the overwhelming majority of the patients were not treated.
Conclusions: Our patients have an homogeneous electroclinical picture to constitute a new epileptic syndrome not included in the ILAE classification. We propose to call it 'benign focal epilepsy in infancy with midline spikes and waves during sleep' (BIMSE).