Influence of gender and age on upper-airway length during development

Obstructive sleep apnea has a strong male predominance in adults but not in children. The collapsible portion of the upper airway is longer in adult men than in women (a property that may increase vulnerability to collapse during sleep). We sought to test the hypothesis that in prepubertal children, pharyngeal airway length is equal between genders, but after puberty boys have a longer upper airway than girls, thus potentially contributing to this change in apnea propensity.

Sixty-nine healthy boys and girls who had undergone computed tomography scans of their neck for other reasons were selected from the computed tomography archives of Rambam and Carmel hospitals. The airway length was measured in the midsagittal plane and defined as the length between the lower part of the posterior hard palate and the upper limit of the hyoid bone. Airway length and normalized airway length/body height were compared between the genders in prepubertal (4- to 10-year-old) and postpubertal (14- to 19-year-old) children.

In prepubertal children, airway length was similar between boys and girls (43.2 +/- 5.9 vs 46.8 +/- 7.7 mm, respectively). When normalized to body height, airway length/body height was significantly shorter in prepubertal boys than in girls (0.35 +/- 0.03 vs 0.38 +/- 0.04 mm/cm). In contrast, postpubertal boys had longer upper airways (66.5 +/- 9.2 vs 52.2 +/- 7.0 mm) and normalized airway length/body height (0.38 +/- 0.05 vs 0.33 +/- 0.05 mm/cm) than girls.

Although boys have equal or shorter airway length compared with girls among prepubertal children, after puberty, airway length and airway length normalized for body height are significantly greater in boys than in girls. These data suggest that important anatomic changes at puberty occur in a gender-specific manner, which may be important in explaining the male predisposition to pharyngeal collapse in adults.