Abstracts

Rationale: Children with chromosome 15q11.2-13.1 duplication syndrome (Dup15q) are at higher risk for developmental delay, epilepsy of variable severity, mild to severe intellectual disability, hypotonia, autistic behavior, language difficulties and minor dysmorphic features. Even though children with Dup15q are frequently evaluated in epilepsy monitoring units their encephalographic (EEG) patterns during sleep are not well described. Methods: We conducted a retrospective chart review of overnight EEG recordings of children with Dup15q admitted in 3 level 4 epilepsy monitoring units (Massachusetts General Hospital, New York University Langone Medical Center, Minnesota Epilepsy Group). All centers have certified specialty clinics for children with Dup15q. The EEGs were reviewed and scored manually by board certified pediatric epileptologists and sleep medicine specialists. Results: 12 children were included in our study (7 males and 5 females) with mean age of 8 years (range 3-13). 11 children have isodicentric duplication of the chromosome 15 and 1 has interstitial 15q11.2-13.1 duplication of chromosome 15. Our patients had overnight EEG for evaluation of seizure like activity and 11 are diagnosed with epilepsy and on at least one antiepileptic medication. All the children have developmental delays with diagnosis of autism spectrum disorder. Three different EEG patterns were observed in our cohort: Pattern 1: Alpha delta sleep was observed in 4 out of 12 children (2 males) for which the data were available. Alpha-delta sleep in non rapid REM sleep was defined as the appearance of prominent alpha activity (frequency of 8-13 Hertz) on delta waves (frequency of 0.5-2 Hertz). Pattern 2: 10 out of 12 children (6 males) had continuous spike-wave during slow wave sleep (CSWS). CSWS was defined as continuous unilateral or bilateral epileptiform activity that occupied more than 50% of slow wave sleep. 9 out the 10 children have clinical seizures and all the children in this group have developmental delay. Pattern 3: 8 out of 12 children (5 males) had frequent bursts of high amplitude and fast frequency activity (12-15 Hertz) during non rapid REM that was disrupting the architecture of the sleep recording. Conclusions: This is the first report of electroencephalographic patterns during sleep of children with Dup15q reporting alpha delta rhythms, CSWS and high amplitude fast frequencies. Alpha delta rhythms are described in children with dysautonomia and/or mood disorders and CSWS in children with developmental regression. The significance of these findings in cognitive function and epilepsy for the children in our cohort needs to be determined with follow up studies.