Larynx height and voice pitch: possible predictors of obstructive sleep apnea in adults? An intriguing hypothesis

Excerpt

Obstructive sleep apnea (OSA) is characterized by repetitive collapses (apneas) or near collapses (hypopneas) of the upper airway (UA) during sleep, resulting in intermittent hypoxemia and increased sympathetic arousal [1]. The prevalence of OSA in the general adult population is reported to be 24% among men and 9% among women [1]. Adult humans are the only animals to suffer from OSA. There are “some exceptions that prove the rule”, such as the English bulldog and other obese animals (for example the Yucatan miniature pig and the Zucker rat), which are known for accumulating fat in pharyngeal soft tissues. It has been postulated that OSA is an anatomic illness caused by evolutionary changes in the human UA [2]. In less evolved mammals, we observe that the anatomy of UA guarantees very efficient respiration and deglutition, with a much less sophisticated mechanism than that in humans [3]. The epiglottis is located much higher than that of the adult human; it is located just behind the soft palate to guide the locking of the larynx directly in the nasopharynx, thus providing an air channel directly from the external nares to the trachea [3]. Food passes on either side of the interlocked epiglottis downwards into the esophagus without interfering with the patent airway (with no risk of aspiration of food) [3]. An interesting detail is that the oropharynx does not exist, and the tongue is entirely located within the oral cavity. Therefore, it would appear that in most mammals, there are no issues with maintaining the patency of the UA during sleep [3]. …