CHARACTERISTICS OF THE GENIOGLOSSUS AND MUSCULUS UVULAE IN SLEEP-APNEA HYPOPNEA SYNDROME AND IN SNORERS

Genioglossus (GG) activity has been extensively studied by electromyog raphic recordings in the investigation of the pathophysiology of sleep anpnea-hypopnea syndrome (SAHS). However, the effective force develop ed by this upper airway (UA) dilator muscle depends on its metabolic a nd histochemical characteristics. The aim of this study was to compare the metabolic and fiber type characteristics of two UA dilator muscle s, musculus uvulae (MU) and GG, in 17 patients with SAHS and in 11 non apneic snorers. MU and GG samples were obtained during uvulopalatophar yngoplasty. Anthropomorphic characteristics were similar in snorers an d patients with SAHS, who differed only in the presence of sleep-relat ed breathing abnormalities. MU glycolytic, glycogenolytic, and anaerob ic enzyme activities were significantly greater in patients with SAHS than in snorers. These differences were not observed for GG. MU and GG enzyme activities differed only in snorers. The proportion of type I muscle fiber was greater in GG than in MU, but it was similar in patie nts with SAHS and snorers for each muscle. Type IIA and IIB muscle fib ers were, respectively, in greater and smaller proportions in patients with SAHS than in snorers. We conclude that (1) the differences in me tabolic characteristics between patients with SAHS and snorers are not observed in all UA muscles, and (2) similar histochemical differences are observed in GG and MU between these two groups, thus suggesting t hat these differences may be implicated in the pathophysiology of SAHS .