It is not fully understood why habitual snoring frequently progresses to obstructive sleep apnea syndrome (OSAS). Vibrations per se may cause peripheral nerve lesions. Therefore, snoring vibrations could cause nervous lesions, leading to impaired reflex activation of dilating muscles at inspiration. In this study, the methodology for quantitative sensory testing in the oropharynx was developed, and the presence of sensory nerve lesions in patients with OSAS and snoring was evaluated.
Vibration detection thresholds (VDTs) and/or cold detection thresholds (CDTs) were tested at the tonsillar pillars, tongue, lip, and finger in 23 nonsnoring individuals, 13 habitual snorers (apnea-hypopnea index [AHI] < 10), and 31 patients with OSAS (AHI > 20).
At tonsillar pillars, there were significant gender differences in both VDT and CDT, with women having lower thresholds. VDT showed no significant differences between any of the three groups when men only were tested. Two nonsnoring control subjects could not detect vibrations at all. When both genders were tested, there was significant difference only between nonsnorers and patients with OSAS (p = 0.003). CDT showed significant differences between nonsnorers and snorers (p = 0.001) and also between nonsnorers and patients with OSAS (p < 0.001), but not between snorers and patients with OSAS. CDT was easier to test than VDT with low variability in nonsnorers.
CDT gave more discriminative results than VDT. Signs of sensory nervous lesions were present in the oropharynx of most patients with OSAS and some snorers, supporting the hypothesis of a progressive oropharyngeal nervous lesion. CDT testing could be a useful clinical method to evaluate the degree of oropharyngeal nervous lesions in patients who snore and in those with OSAS.