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Objectives/hypothesis: The aim of this study was to investigate the effect of obstructive sleep apnea (OSA) on the parameters of olfactory functions (odor threshold, odor discrimination, and odor identification tests) for orthonasal olfaction, retronasal olfactory testing, and olfactory bulb (OB) volumes.
Study Design: Prospective clinical study.
Methods: This study was carried out in 78 volunteers between the ages of 20 and 60 years. The mean age of the patients was 46 ± 10.1 years. Patients were divided into three groups according to polysomnography results: 1) a control group, 2) a mild to moderate OSA group, and 3) a severe OSA group. Clinical features of the participants were evaluated with the Epworth Sleepiness Scale. Orthonasal and retronasal olfactory testing were performed with Sniffin' Sticks olfactory testing and retronasal olfactory testing, respectively. Olfactory bulb volumes were measured by planimetric manual contouring on magnetic resonance imaging (MRI).
Results: The current investigation produced four major findings: 1) The apnea-hypopnea index had a significant and strong negative correlation with odor threshold scores and odor discrimination scores; 2) The apnea-hypopnea index was significantly negatively correlated with odor identification score and both right and left OB volumes; 3) retronasal olfactory scores were not significantly affected by OSA; and 4) continuous O2 saturation had a significant positive correlation on orthonasal olfactory functions, particularly the odor threshold and discrimination scores.
Conclusions: This study demonstrated that OSA had significant negative effects on all orthonasal olfactory tasks, especially on threshold and discrimination. MRI also revealed volumetric shrinkage of OB volumes.
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http://dx.doi.org/10.1002/lary.24565 | DOI Listing |
ORL J Otorhinolaryngol Relat Spec
July 2025
Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany.
Introduction: Olfactory training (OT) is known to be beneficial for olfactory disorders. The study aimed to explore whether the familiarity of odors influences the effectiveness of OT.
Methods: Participants were divided into three groups: original training (OG), modified training with familiar odors to the Japanese population (FG), and modified training with unfamiliar odors to the Japanese population (UFG).
Front Neurosci
July 2025
Department of Brain Function, School of Medical Sciences, University of Fukui, Matsuoka, Fukui, Japan.
Mammalian sensory cortices detect changes both inside and outside of the body. They identify sensory information from the surrounding world, evaluate the current situation, and generate top-down signals to induce emotional and behavioral outputs. The cortices also detect physiological changes inside of the body, such as internal pain, thirst, fever, and retronasal odors.
View Article and Find Full Text PDFLaryngoscope
July 2025
Department of Otorhinolaryngology, Bilkent City Hospital, University of Health Sciences, Ankara, Türkiye.
Objective: To compare the efficacy of classical olfactory training (COT) protocols with a novel dual-route method targeting both orthonasal and retronasal pathways in the management of postinfectious olfactory dysfunction (PIOD), and to explore the neurotherapeutic potential of terpene-based odorants.
Methods: One hundred and seventeen patients diagnosed with PIOD received either conventional olfactory training or a modified protocol that integrates retronasal stimulation. The terpene profile of administered odorants was evaluated for its contribution to olfactory and cognitive outcomes.
Biol Cybern
July 2025
Statistics Department, Virginia Commonwealth University, 1015 Floyd Ave, Richmond, 23284-3083, VA, USA.
A fundamental question in neuroscience is how sensory signals are decoded from noisy cortical activity. We address this question in the olfactory system, decoding the route by which odorants arrive into the nasal cavity: through the nostrils (orthonasal), or through the back of the throat (retronasal). We recently showed with modeling and novel experiments on anesthetized rats that orthonasal versus retronasal modality information is encoded in the olfactory bulb (OB, a pre-cortical region).
View Article and Find Full Text PDFFoods
March 2025
School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, China.
Flavor is an important property affecting consumer acceptance, yet little is known about the correlation between the sensory attributes, volatile compounds, and consumer preference during cider consumption. This study was the first to evaluate which sensory attributes of commercial apple ciders in China were preferred by Chinese consumers. Meanwhile, GC-MS and GC-IMS were conducted to characterize the aroma release both in orthonasal and retronasal olfactory perceptions.
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