0941 UNILATERAL CONTINUOUS SPIKE AND WAVES DURING SLOW SLEEP (CSWS): CLINICAL AND SLEEP EEG FEATURES

Abstract

Introduction: Continuous spikes and wave during slow sleep (CSWS) is an age-related epileptic encephalopathy of childhood that is often associated with sleep-related seizures, neurocognitive regression, and an EEG pattern characterized by the dominant presence of bilateral spike-wave discharges during sleep. While focal and lateralized electrographic features have been described in association with this entity, there is little known about the clinical and sleep EEG features of unilateral CSWS. Methods: A retrospective analysis of consecutive 21+-channel pediatric sleep EEG studies at our institution from the years 2011-2016 was performed. If unilateral CSWS was demonstrated, medical charts were then subsequently reviewed for clinical information that included chief complaint and reason for EEG; neurodevelopmental history; neurobehavioral and neuropsychiatric co-morbidities; neurological exam features; and neuroimaging study findings. Results: Out of a total of 5,190 consecutive pediatric sleep EEG studies performed over this 6-year period, only 4 children (or 0.08%) demonstrated unilateral CSWS (2M;2F; aged 3-3-8.5 years). All but one of these children demonstrated a well-controlled sleep-related seizure disorder that was largely responsive to a singular seizure medication. In addition, all of these childen demonstrated normal speech and language development; an absence of attention deficits or any neurobehavioral or neuropsychiatric co-morbidities; a non-lateralized neurological examination; and a completely normal or benign MR neuroimaging study. Their EEG patterns were characterized by the unilateral and dominant presence of moderate-to-high amplitude spike-wave discharges exclusively relegated to an isolated cerebral hemisphere (3L;1R), while occupying more than 85% of the recording during sustained non-REM sleep; as well as a broad field of involvement that included the ipsilateral parietal and/or frontal regions. Conclusion: Unilateral CSWS is a rare electroclinical entity that is typically associated with a well-controlled sleep-related seizure disorder. It may be differentiated clinically from bilateral CSWS by a relatively intact neurodevelopment and neurocognition; an age-appropriate language development; and an absence of neurobehavioral abnormalities and attention deficits. It may be distinguished electrographically from the more common benign focal epilepsies of childhood by their broader field of involvement throughout the hemisphere; the absence of independent contralateral spike-wave discharges; and their dominant expression during sustained non-REM sleep.