The effect of obstructive sleep apnea on olfactory functions

Area of Science:

• Neurology
• Ophthalmology
• Sleep Medicine

Background:

• Obstructive sleep apnea (OSA) is a common sleep disorder with potential systemic effects.
• Olfactory dysfunction can significantly impact quality of life.
• The relationship between OSA and olfactory function requires further elucidation.

Purpose of the Study:

• To investigate the impact of obstructive sleep apnea (OSA) on olfactory function parameters.
• To assess the effect of OSA on orthonasal and retronasal olfaction.
• To determine if OSA influences olfactory bulb (OB) volumes.

Main Methods:

• Prospective clinical study involving 78 volunteers aged 20-60.
• Participants categorized into control, mild-to-moderate OSA, and severe OSA groups based on polysomnography.
• Olfactory function assessed using Sniffin' Sticks; OB volumes measured via MRI.

Main Results:

• Apnea-hypopnea index negatively correlated with odor threshold, discrimination, and identification scores.
• Significant negative correlation found between apnea-hypopnea index and both right and left OB volumes.
• Continuous O2 saturation positively correlated with orthonasal olfactory functions.

Conclusions:

• Obstructive sleep apnea (OSA) significantly impairs orthonasal olfactory functions, especially odor threshold and discrimination.
• MRI confirmed volumetric reduction in olfactory bulb volumes in OSA patients.
• Retronasal olfactory testing was not significantly affected by OSA.