Effect of mandibülar advancement splint (MAS) therapy on daytime sleepiness and neuropsychological function in obstructive sleep apnoea syndrome (OSAS)

Rationale: Effective treatment of OSAS with nasal CPAP can improve sleepiness and neuropsychological function. Aim: To assess whether similar benefits are achievable with MAS therapy. Methods: Patients received MAS (A) therapy for 4 w-eeks and Control (B) for 4 weeks, one week apart, following randomisation to treatment order. The Control consisted of an inactive oral plate. At the end of each 4-week period, subjects completed the Epworth Sleepiness Scale (ESS), a battery of neuropsychological tests, and underwent polysomnography followed by a Multiple Sleep Latency Test (MSLT). Complete response (CR) to treatment was defined as a reduction in the RDI to <5/hr and partial response (PR) as a ≥50% reduction in RDI but remaining ≥5:lir. Results: Baseline characteristics, mean (SD), of the 27 patients (20M. 7F) studied to date: age 49(11 ) yrs. BMI 28.515.5) kg/m:, RDI 24.3(14.8) /hr and MinSaO, 87(5) %. The MAS resulted in significant improiements, mean (SEM), in RDI (22.9(3.0) vs 9.3( 1.5) /hr). MinSaO; (87( 1 ) vs 91( 1 ) %). and ESS score (9(1) vs 6( 1 )), compared to the Control, (P<0.001 ). CR was achieved in 11 patients and PR in 5. There was a trend towards an improved mean SL on MSLT with the MAS (8.3(0.6) vs 9.9(0.9) min: P=0.05). There were no significant changes in any neuropsychological function test scores between active treatment and the Control for the group overall, however, in subjects who were subjectively sleepy at baseline (ESS 10), choice reaction time was significantly taster with active treatment (0.693 vs 0.601 sees; PO.05). Conclusions: These preliminary data confirm that MAS therapy is effective at improving subjective sleepiness, but it remains uncertain whether it impacts on objective sleepiness and neuropsvcholocical function.