Abstracts

Rationale: Dravet syndrome (DS) is a genetic epileptic encephalopathy, characterized by infantile onset of refractory seizures, developmental slowing and often behavioral problems. Parents of children with DS frequently complain that their child has sleep problems. There is a bidirectional relationship between epilepsy and sleep. Poor sleep exacerbates seizures, and seizures and epileptiform activity lead to fragmented sleep. We studied the frequency and nature of sleep disturbances in children with DS.Methods: A Sleep Disturbance Scale for Children (SDSC) questionnaire was sent to 89 families (91 affected participants). Questions about nocturnal seizures and the use of sleep medications were asked. 15 children had 1-2 nights of at-home pulse oximetry; with selection towards those reported to have sleep problems.Results: Questionnaires were returned on 50/91 children with DS including 25 female, with a mean age 14 years (range 2-36 years). 45/50 (90%) had SCN1A mutations, 42 were de novo, 2 were siblings with a mosaic father and 1 the child of a mother with DS. 21/50 (42%) children had a total sleep score indicative of sleep disturbance. Subscores indicated difficulty initiating and maintaining sleep (21/50, 42%), sleep-wake transition disorders (17/50, 34%), and sleep breathing disorders (16/50, 30%). 18/50 (36%) children took medication to assist sleep, predominantly melatonin (10/18). Only 12/18 had a pathogenic total sleep score. 9/18 had difficulty initiating and maintaining sleep, including 4 on melatonin. 25/50 (50%) children had had nocturnal seizures in the past 6 months, with 8% (n=4) experiencing them nightly. Of 10/50 (20%) with disorders of excessive somnolence, only 3 reported nocturnal seizures. Sleep-wake transition disorders scores predominantly comprised frequent (>3nights/week) jerks (11/17) or nocturnal hyperkinesia (16/17). Overnight pulse oximetry on 15 patients with mean age 7.7 years (range 2-26 years). 13/15 (87%) had a higher oxygen desaturation index (>3%), and 5/15 (33%) higher mean pulse rates in sleep, than the normative values for age. There was no evidence of obstructive sleep apnea. Only 1 patient reported nocturnal seizures during pulse oximetryConclusions: Almost half of the children with DS have sleep difficulties of variable nature. Despite sleep medication in 18 children, 12 had ongoing sleep problems. We found that of 42% with difficulty in sleep initiation or maintenance, only 9/21 were on medication suggesting more widespread use should be considered. Overnight pulse oximetry was well tolerated by the participants, despite the presence of intellectual and behavioral issues. The higher than expected oxygen desaturation and mean pulse rates on pulse oximetry may reflect unrecognized nocturnal seizures. Clinical evaluation and appropriate investigation with polysomnography of sleep is required to delineate the cause and initiate appropriate interventions. This will improve quality of life for child and family and has the potential to ameliorate developmental outcome.