The effect of nasal structure on olfactory function in patients with OSA

The aim of this study was to investigate the relationship between nasal structure and olfactory function in patients with obstructive sleep apnea (OSA). Olfaction and nasal structure of 76 adults with OSA diagnosed by polysomnography were measured using acoustic rhinometry and the Sniffin, Sticks (SS) smell test at Anzhen Hospital, a major academic center in Beijing, China. We tested the hypothesis that nasal structure in these patients would correlate with objectively measured olfactory performance. Minimum cross-sectional area (MCA) of the nose was significantly correlated with SS composite score ( r = 0.434, p < 0.001), a result that was driven by two of the test’s three components: olfactory threshold (OT) ( r = 0.385, p = 0.001) and olfactory discrimination (OD) ( r = 0.370, p = 0.001) but not olfactory identification (OI) ( p > 0.05). Additionally, nasal volume (NV) was associated with composite SS score ( r = 0.350, p = 0.002), a finding driven by OT ( r = 0.283, p = 0.014). These data suggest that nasal structure affects parameters of olfactory function, likely via alterations in nasal airflow. Thus, anatomic abnormalities and diseases involving airflow (such as OSA) may cause, in part, olfactory dysfunction that is amenable to treatment. We speculate that surgery that alters nasal volume and MCA may improve olfactory performance.