O050 Hypersomnolence in children: the diagnostic dilemma

BACKGROUND: Excessive daytime sleepiness (EDS) is reported to affect up to 20% of pre-pubertal children and 50% of adolescents. EDS can be due narcolepsy and idiopathic hypersomnolence (IH). Currently diagnosis is by a multiple sleep latency test (MSLT) with protocols adapted from adults. The aim of this study was to describe the results of MSLTs in a paediatric population and assess whether a 5th nap altered diagnosis. METHODS: Retrospective analysis of 253 MSLTs at a single tertiary paediatric centre from May 2004 – Jan 2021 with consent obtained in 214 patients. Narcolepsy defined as a mean sleep latency (MSL) <8min with ≥2 sleep onset REM (SOREM). IH defined as a MSL < 8 minutes with <2 SOREMs. Results outside these parameters were grouped as hypersomnolence not otherwise specified (HNOS), with ambiguous HNOS defined as MSL 8–12 minutes or ≥2 SOREM. PROGRESS TO DATE: There were 108 (50%) females, 132 (62%) >12 years old (range 3.3–19.4 years) and 17 patients had repeat studies. Narcolepsy was diagnosed in 48 (22%) and IH in 22 (10%). Criteria for ambiguous HNOS were met by 43 (20%) patients including 11 (5%) with MSL >12 minutes with ≥2 SOREMs. A 5th nap was performed in 58 (27%) MSLTs which did not change the diagnosis. Obstructive sleep apnoea was diagnosed in 48 (22%) patients and 27 (13%) had elevated periodic limb movement index. INTENDED OUTCOME AND IMPACT: Applying current MLST criteria in children may significantly under-estimate diagnostic categories for paediatric EDS as evidenced by the ambiguous HNOS.