1
Introduction
It is widely accepted that particular mouth and tongue positions affect patency of the upper airway. Specifically, mouth opening is believed to decrease the cross-sectional area, whereas tongue protrusion is believed to increase the dimensions of the upper airway. Variable response to mouth opening and tongue protrusion may be responsible for inconsistent response to targeted treatment options for obstructive sleep apnea/hypopnea syndrome (OSAHS).
Nasal obstruction has been postulated to decrease the cross-sectional area of the airway as a result of compensatory mouth breathing. However, the expected decrease in airway size with mouth opening is not universal. Although nasal obstruction is a risk factor for the development of OSAHS, studies have shown limited and unpredictable efficacy of nasal surgery as a treatment for OSAHS. These inconsistencies may be explained in part by the unpredictable patterns of change seen in the hypopharyngeal airway with mouth opening.
Similarly, studies have shown that tongue protrusion does not universally increase the cross-sectional area of the hypopharyngeal airway. These findings may play a significant role in patient selection for genioglossal advancement or hypoglossal nerve stimulation, where genioglossal protrusion is intended to improve the hypopharyngeal airway.
Consideration of the unique anatomic features that contribute to a patient’s upper airway obstruction may facilitate more successful outcomes of OSAHS treatment. It is necessary to characterize the effects of mouth and tongue position on hypopharyngeal airway dimensions and determine the prevalence of patients who exhibit atypical patterns of change.
2
Airway Examination
During anatomic staging utilizing Friedman tongue position and lingual tonsil hypertrophy grading, visualization of the hypopharyngeal airway in different oral positions should be included as part of a patient’s initial assessment. In addition to identifying any degree of hypopharyngeal obstruction, this procedure will guide the selection of patients seeking targeted OSAHS treatment. Because multiple views of the hypopharyngeal airway with varying degrees of mouth opening and tongue protrusion provide a better representation of the airway, awake endoscopy is a complement to drug-induced sleep endoscopy (DISE). Trends of obstruction observed at different magnitudes of oral position may play a role in choosing patients who are likely to respond to surgical treatment.
Upon visualization by flexible fiber-optic scope, the hypopharyngeal airway should be observed as the patient gradually opens their mouth with the tongue in neutral position. Similarly, observation of the hypopharyngeal airway as the patient gradually protrudes their tongue from a neutral position should be noted. Figs. 19.1 and 19.2 demonstrate expected and atypical patterns of change in the hypopharyngeal airway with oral positioning.
