Palatal Sensory Threshold Reflects Nocturnal Hypoxemia and Airway Occlusion in Snorers and Obstructive Sleep Apnea Patients

Study Objectives: Upper airway sensory deficit has been reported to be associated with snoring or obstructive sleep apnea. There are limited data on the correlation between disease severity and upper airway sensation. In this study, we investigated the relationship between clinical parameters and standardized palatal sensory threshold (SPST) using Semmes Weinstein monofilaments. Methods: We recruited 40 snorers and 19 control subjects. Palatal sensory threshold was measured in all study subjects, using Semmes Weinstein monofilaments. Standardized palatal sensory threshold was determined by subtraction of hard palate sensation from uvular sensation. All subjects with snoring underwent a modified Muller maneuver during wakefulness before polysomnography. Results: SPST was higher in snorers than in control subjects, but did not differ according to the severity of obstructive sleep apnea. Patients with higher SPST (>= 0.45 g/mm(2)) were older and had more severe hypoxemia indices: lower nadir oxyhemoglobin saturation (SpO(2)) and higher percentage of sleep time at < 90% SpO(2). Adjusted for age, sex, neck circumference, and body mass index, SPST was correlated with the apnea-hypopnea index and hypoxemia indices. With a cutoff value >= 0.45 g/mm(2), the sensitivity of SPST for nocturnal hypoxemia (nadir SpO(2), < 80%) was 81.3%. Patients with higher SPST (>= 0.45 g/mm(2)) showed more airway occlusion in modified Muller maneuver, than those with lower values. Conclusions: The SPST measured using Semmes Weinstein monofilaments reflects nocturnal hypoxemia and airway occlusion. This test provides a potential tissue marker of the severity of hypoxemia in patients who snore.