14 and 6 Hz like spike wave activity is a common finding in in young patients with Prader-Willi syndrome.

STUDY OBJECTIVES: Our aim was to characterize the 14 and 6 like spike wave activity seen on electroencephalogram (EEG) in children with Prader-Willi syndrome (PWS) undergoing polysomnogram (PSG).

METHODS: We performed a retrospective review of children with PWS and healthy controls who underwent diagnostic PSGs between January 1, 2007 to December 31, 2020 at SickKids, Toronto, Canada. EEGs from the PSGs were reviewed for the presence of the 14 and 6 like spike wave activity and its characteristics. Clinical correlation of the EEG variant with sleep disordered breathing indices from the PSG was also evaluated.

RESULTS: 94 children with PWS and 50 healthy controls were included. The age, median (IQR) for the cohort was 1.42 (0.6, 4.2) years. There were 50 (53.2%) males in the PWS cohort. The EEG variant prevalence in this cohort was 51.0% (n=48) in children with PWS and 0% for the healthy controls. 14 and 6 Hz like spike wave activity was bilateral in 52% (25/48) children with PWS. The waves had a negative deflection in almost all patients 44/48 (92%) with PWS. It was predominantly located in the frontal leads for children with PWS, 23/48 (47.9%). It most frequently occurred during NREM stage 2 sleep for children with PWS, 25/48 (52.0%). The mean (SD) frequency was 6.8 (0.97) Hz. The median (IQR) length of the waves was 1.1 (0.8, 1.4) seconds in children with PWS. There was no correlation between the presence of the EEG variant and sleep disordered breathing indices in children with PWS.

CONCLUSIONS: 14 and 6 Hz like spike wave activity EEG variant was present in more than 50% of a pediatric cohort of PWS as compared to 0% in healthy children. This EEG variant did not appear to be associated with sleep disordered breathing indices in children with PWS and is of unknown clinical significance.