Two-point palatal discrimination in patients with upper airway resistance syndrome, obstructive sleep apnea syndrome, and normal control subjects

Study objective: To compare the results of a two-point palatal discrimination response in normal subjects (n = 15), patients with obstructive sleep apnea syndrome (OSAS) [n = 15], and patients with upper airway resistance syndrome (LIARS) [n = 15] matched for age, sex, and body mass index. Design: Comparison study of three subject groups. Setting: A sleep-disorders clinic. Subjects: Participants were selected based on clinical questionnaire, clinical evaluation, and polysomnography. Intervention: Polysomnography involving measurement of flow limitation with a nasal cannula pressure transducer system and of respiratory effort with esophageal pressure was performed in order to recognize the presence, absence, and types of sleep-disordered breathing. The 45 subjects were submitted to a two-point palatal discrimination study during wakefulness performed by an investigator blinded to the polysomnogram results. Results: Patients with OSAS had a clear impairment of their palatal sensory input with a significant decrement in two-point discrimination, but patients with LIARS and normal control subjects had similar responses. Patients with LIARS exhibited at least intermittent snoring in most cases. Conclusion: The normal responses seen in patients with LIARS indicate that these patients are more capable of transmitting sensory inputs than patients with OSAS. This may be one element explaining the difference in arousal response previously documented in LIARS compared to OSAS.