Abstracts

Rationale: The prevalence of interictal epileptiform discharges (IED) in patients less than one of year of age referred for polysomnogram (PSG) studies is unknown. We sought to determine the prevalence of IED in this patient cohort, raising the possibility that abnormal brain electrical activity may contribute to the sleep disorder. Specific aims of this study include (i) identify prevalence of IED in referred patients less than one year of age, (ii) quantify and characterize sleep stage(s) during which IED occur, (iii) correlate reason for PSG referral and IED frequency. Methods: Charts of infants less than 1 year of age referred for PSG at the Alberta Children's Hospital (ACH) from 2011 to 2013 inclusive were reviewed. Quantification of IED was performed by a pediatric sleep neurologist for the entire study, unless there were greater than 20 IED within the first hour, in which case quantification was done for three 1 hour blocks (beginning, middle and end). Descriptive statistics was used for data analysis. Results: 53 patients met study criteria, 3 patients were excluded due to incomplete EEG data. One patient's study was analyzed in three 1 hour blocks, as there were greater than 20 IED in the first hour and the remaining 49 studies were analyzed for the entire duration. Of the 50 patients, 14 (28%) had IED. One patient had generalized IED, the remainder were focal. Of the patients with IED, 1 (7%) had IED in N1 sleep, 9 (64%) in N2 sleep, 11 (78%) in N3, and 5 (36%) in REM sleep. The most common comorbid condition in patients with IED was Trisomy 21 (6 out of 14 [43%]), followed by Pierre Robin (3 out of 14 [21%]). Conclusions: Infants under one year undergoing PSG have a prevalence of IED of 28%. IED were seen mostly in N2 and N3 sleep stages. The most common condition seen in infants with IED was Trisomy 21. Our findings suggest that a more detailed examination of the EEG, and potentially a full EEG during PSG, may be warranted in this population, which may prompt subsequent referral for formal neurological consultation.