Long term follow-up of lesional and non-lesional patients with electrical status epilepticus in slow wave sleep

Objectives - A retrospective study has been done at the Bethesda Children's Hospital Epilepsy Center with those patients whose EEG records fulfilled in one or more records the criteria of electrical status epilepticus in slow wave sleep (ESES) pattern, occupying at least 75% of NREM sleep with bilateral discharges, and had detailed disease history and long term follow-up data, between 2000 and 2012. Patients and methods - Thirty-three patients (mean 11.1 ±4.2 years of age) were studied by 171 sleep EEG records. Sleep was recorded after sleep deprivation or during spontaneous sleep at least for one hour length of NREM. From the 492 EEGs, 171 sleep records were performed (average five/patient). Average follow-up time was 7.5 years. Eighty-two ESES records have been analyzed in 15 non-lesional and 18 lesional (11 with dysgenetic and seven with perinatal - asphyxic or vascular origin) patients. Variability of seizure types, seizure frequency and frequency of status epilepticus was higher in the iesional group. Impairment of the cognitive functions was moderate and partial in the non-lesional, while severely damaged in the lesional group. Results - EEG records of 29 patients showed unihemispherial spike fields with a perpendicular axis (in anterior, medial and posterior variants) to the Sylvian fissure, regardless their lesional or non-lesional origin. Only three (lone non-lesional and two lesional) patients had bilateral synchronous spike-wave discharges with bilateral symmetric frontocentral spike fields. The individual discharges of the sleep EEG pattern were very similar to the awake interictal records except their extension in time and field, their increased number, amplitude, and continuity of them and furthermore in the increased trans-hemispheral propagation and their synchronity. Conclusions - Assumed circuits involved in the pathome-chanism of discharges during NREM sleep in ESES are discussed based on our findings.