Impact of obstructive sleep apnea syndrome on olfactory and gustatory capacity

Only a few studies have investigated olfactory function in patients with obstructive sleep apnea syndrome (OSAS) using psychophysical testing, and there is a scarcity of data regarding taste evaluation in the existing literature. The primary objectives of this study were to assess both smell and taste in patients with OSAS and to explore the correlation between the severity of symptoms and sensory perception. A total of 85 OSAS patients and a control group comprising 81 subjects were enrolled. Initial assessments included anamnesis, nasal endoscopy, and the completion of questionnaires (Epworth Sleepiness Scale, Visual Analogue Scale, Questionnaire of Olfactory Disorders, and the importance of olfaction questionnaire). The diagnosis of OSAS was confirmed by polysomnography, while nasal airflow was evaluated using rhinomanometry. Olfaction was assessed using the Sniffin' Sticks test, and the Threshold-Discrimination-Identification (TDI) score was calculated. Taste evaluation was conducted in a subgroup of participants (42 patients, 38 controls) using taste strips. The mean TDI score was 31 +/- 5.6 for OSAS patients and 35 +/- 4.6 for controls, indicating a significant difference (P < 0.001). Similarly, the taste score was 7 +/- 3.0 for OSAS patients and 12.6 +/- 3.2 for controls (P < 0.001). No correlations were observed between TDI and Apnea Hypopnea Index (AHI) (r = -0.12; P = 0.28), as well as between the taste score and AHI (r = -0.31; P = 0.22). However, a weak but significant correlation between TDI score and Epworth Sleepiness Scale was detected (r = -0.05; P = 0.002). The study revealed a significant decrease in sensory perception among patients with OSAS, though open questions persist about the pathophysiology.