Heterogeneity in vertical positioning of the hyoid bone in relation to genioglossal activity in men.

The aim of this study was to investigate whether there is any relationship among genioglossus (GG) baseline electromyographic (EMG) activity, upper airway resistance, and sex. We hypothesized that GG baseline EMG activity and its response to pharyngeal partial occlusion may be heterogeneous in men but homogeneous in women. Lateral head roentgenograms were obtained in the upright standing position with the head at natural posture from age-matched, healthy, 16 men and 15 women. A miniature balloon was placed in the retroglossal pharynx, and a record of GG EMG response was measured. The database was divided by sex and further categorized based on the increment of GG EMG response to inflation of the balloon. Both sexes included responsive subjects showing a greater GG EMG activity increase than the mean values and a counterpart, ie, a nonresponsive group. When the two subgroups were compared, the hyoid bone of the responsive subjects positioned more inferiorly than that of nonresponsive subjects in men (P < .05). When men and women were compared, most cephalometric measurements were significantly larger in the male responders, but no difference was shown in the nonresponders. We concluded that men with a lower hyoid bone show greater GG reflexive response to the partial oropharyngeal obstruction.