PALATAL MUSCLE ELECTROMYOGRAM ACTIVITY IN OBSTRUCTIVE SLEEP-APNEA

Eight subjects (5 men, 3 women, ages 27 to 55) with obstructive sleep apnea syndrome (OSAS) were studied to quantify and compare electromyog raphic (EMC) activity of levator veli palatini (LVP) and palatoglossus (PC), two velopharyngeal muscles, and genioglossus (CC) during obstru ctive apnea cycles in non-rapid eye movement (NREM) sleep. EMC activit y of three successive preapneic breaths, first and last apneic efforts , and three successive postapneic breaths was quantified for each musc le as peak phasic inspiratory EMC normalized as percent activity of th e last preapneic breath. In all subjects, apnea onset coincided with s imultaneous inspiratory EMC nadir of all three muscles (LVP = 63 +/- 4 0%, PC = 74 +/- 5396, GG = 83 +/- 48%, mean +/- SD activity of last pr eapneic breath). Apnea resolution did not occur until inspiratory EMC of all three muscles simultaneously reached maximal activity, at level s significantly greater than preapneic activity as well as activity of the last preapneic effort (LVP = 215 +/- 205%, PC = 227 +/- 240%, GG = 235 +/- 202%, mean +/- SD activity of last preapneic breath, p < 0.0 5, Fisher's partial least-squares difference [PLSD] test for each musc le). The presence or absence of electroencephalographic arousal at apn ea resolution did not influence these patterns of EMG activity. Inspir atory recruitment of velopharyngeal as well as oropharyngeal muscles a ppears to be associated with upper airway patency during sleep in pati ents with OSAS.