title: Daytime sympathetic hyperactivity in OSAS is related to excessive daytime sleepiness.
abstract: The aim of this study was to investigate the relationships among sympathetic hyperactivity, excessive daytime sleepiness (EDS) and hypertension in obstructive sleep apnoea syndrome (OSAS). Ten newly diagnosed OSAS patients with untreated EDS and daytime hypertension underwent polysomnography (PSG) and daytime measurements of plasma noradrenaline (NA), ambulatory blood pressure (BP), muscle sympathetic nerve activity (MSNA) by microneurography and objective assessment of EDS before and during 6 months of compliance-monitored continuous positive airway pressure (CPAP) treatment. One month after the start of CPAP, BP, MSNA and NA were significantly lowered, remaining lower than baseline also after 3 and 6 months of treatment. CPAP use caused a significant improvement of sleep structures, and reduced EDS. A statistical correlation analysis demonstrated that EDS was not correlated with sleep measures obtained from baseline PSG (% sleep stages, apnoea and arousal index, mean oxygen saturation value), whereas daytime sleepiness was significantly correlated with MSNA. Furthermore, MSNA and BP showed no correlation. Our data obtained from selected patients suggest that the mechanisms inducing EDS in OSAS are related to the degree of daytime sympathetic hyperactivity. Additionally, resting MSNA was unrelated to BP suggesting that factors other than adrenergic neural tone make a major contribution to OSAS-related hypertension. The results obtained in this pilot study need, however, to be confirmed in a larger study involving more patients.
authors: Department of Neurological Sciences, University of Bologna, Bologna, Italy. donadio@neuro.unibo.it
authors: Vincenzo
authors: V
authors: Donadio
authors: Rocco
authors: R
authors: Liguori
authors: Roberto
authors: R
authors: Vetrugno
authors: Manuela
authors: M
authors: Contin
authors: Mikael
authors: M
authors: Elam
authors: B Gunnar
authors: BG
authors: Wallin
authors: Tomas
authors: T
authors: Karlsson
authors: Enrico
authors: E
authors: Bugiardini
authors: Agostino
authors: A
authors: Baruzzi
authors: Pasquale
authors: P
authors: Montagna
mesh_terms: D000818:Animals; D045422:Continuous Positive Airway Pressure; D006970:Disorders of Excessive Somnolence / Q000150:complications / Q000209:etiology* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006948:Hyperkinesis / Q000150:complications* / Q000503:physiopathology*; D006973:Hypertension / Q000150:complications; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation; D017286:Polysomnography; D011817:Rabbits; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D016896:Treatment Outcome