Soft palate sensory neuropathy in the pathogenesis of obstructive sleep apnea.

OBJECTIVES/ HYPOTHESIS: In general, obstructive sleep apnea (OSA) seems to be a progressive disorder whose pathogenesis is not fully understood. One hypothesis is that long-standing snoring vibrations cause a local neuropathy in the upper airway, which predisposes to obstructive events during sleep. The aim of this study was to investigate sensory function in the upper airway in a cohort of subjects comprising nonsnorers, snorers, and untreated subjects with OSA, and to correlate data to apnea-hypopnea index (AHI) and duration of snoring.

STUDY DESIGN: Cross-sectional cohort study.

METHODS: Subjects were recruited from primary care hypertension clinics. Whole-night respiratory recordings were performed to determine presence and degree of OSA. Three groups were formed based on AHI and snoring history: 1) nonsnorers (n = 25); 2) snorers, AHI < 10 (n = 32); 3) OSA subjects, AHI ≥ 10 (n = 33). Quantitative cold sensory testing of the soft palate and lip was used to assess neuropathy.

RESULTS: There were no significant differences concerning lip sensory function between groups. Nonsnorers showed significantly lower thresholds for cold (i.e., better sensitivity) in the soft palate compared to both other groups (P < .01). Snorers had lower thresholds than OSA subjects (P < .05). There were significant correlations (P < .01) between decreased sensory function and AHI (r(s) = .41) and to duration of snoring (r(s) = .47).

CONCLUSIONS: The degree of sensory neuropathy in the upper airway correlates with degree of obstructive sleep disorder. Our results strengthen the hypothesis that snoring vibrations may cause a neuropathy in the upper airway, which contributes to the progression and development of OSA.