A systematic review and meta-analysis of upper airway sensation in obstructive sleep apnea - Implications for pathogenesis, treatment and future research directions.

Impaired upper airway sensation may contribute to obstructive sleep apnea (OSA) pathophysiology and could represent a therapeutic target. However, the extent of impaired sensation and its functional role in OSA pathogenesis remains unclear. This study aimed to: 1) evaluate methods of upper airway sensory testing in people with OSA, 2) compare upper airway sensation in people with and without OSA and 3) investigate the potential relationship between upper airway sensation and OSA severity. Major electronic databases were searched for studies that reported methods of upper airway sensory testing in people with OSA (n = 3819). From the selected studies (n = 38), information on the type of sensation, testing methods, validity and test-retest reliability were extracted. Meta-analyses were performed on case-controlled studies and studies that investigated potential relationships between upper airway sensation and OSA severity. Seven categories of sensory tests were reported: olfactory, gustatory, chemical, tactile, vibratory, thermal and perioral neuro-sensation. Testing methods varied widely across studies. No tests were validated in OSA. People with OSA had impaired upper airway sensation to airflow (p = 0.0002), chemical (p = 0.0001), gustatory (p = 0.009), olfactory (p = 0.04), tactile (p = 0.0001) and vibratory (p = 0.005) stimuli. Upper airway sensory impairment increased with OSA severity (p < 0.001). These findings suggest that, while variable across testing methods, people with OSA have impaired upper airway sensation, which is related to increased OSA severity. Development of valid and reliable upper airway sensory testing methods that relate to upper airway function in people with OSA are required to inform future clinical and research practices and identify potential therapeutic targets.