Validation study of a novel approach for assessment of retronasal olfactory function with combination of odor thresholds and identification

Abstract

Purpose The present study aimed to establish a test battery for the clinical assessment of retronasal odor thresholds and retronasal odor identification. Study design Prospective case–control series. Methods Sixty participants (36 women, 24 men, mean age 37.6 ± 19.4 years) were enrolled in this study; 36 were healthy controls and 24 were patients with olfactory dysfunction. Orthonasal olfactory function was assessed with the “Sniffin’ Sticks” test battery. Retronasal olfaction was assessed with oral odorant delivery using special containers for threshold function, and with oral tasteless powders for odor identification. Results Retronasal and orthonasal olfaction were significantly correlated for threshold scores, identification score, and the sum of threshold and identification score (TI score). Validity analyses showed that the retronasal TI score was able to discriminate between healthy controls and patients with olfactory dysfunction. Conclusions Normosmic participants can be distinctly differentiated from patients with olfactory dysfunction using a valid test battery comprised of retronasal threshold and identification tests. Based on the current findings, we advocate a TI score of 16 as a cut-off between patients and controls. Therefore, TI scores of 17 and above would indicate retronasal normosmia.

Ortho‐ and Retronasal stimulations with specific food odours: Hedonic and familiarity ratings are related to chemosensory pleasure scale (CPS) scores

“…Indeed, it has been shown that some physiological factors related to gustatory function, such as salivation, enzymes, chewing…, could influence retronasal stimulation. 58 The straw technique used in the present work, and in recent studies, 18,46,47 is another technique of retronasal stimulation in which no simultaneous gustatory stimulation occurs. This technique is non-invasive and allows a more ecological stimulation insofar as retronasal stimulation occurs during food intake, i.e., volatile molecules reach the olfactory epithelium via rhino-pharyngeal crossroad.…”

“…The retronasal stimulation was based on the “straw” technique developed by Chen and Halpern 46 and used in recent studies 18,47 . Six millitres of each odorant were placed in a 30 mL amber glass bottle.…”

“…The retronasal stimulation was based on the "straw" technique developed by Chen and Halpern 46 and used in recent studies. 18,47 Six millitres of each odorant were placed in a 30 mL amber glass bottle. Participants were asked to pinch their nose and to inhale the fragrant air (containing the odour) through a straw placed in a hole of the bottle cap.…”

Orthonasal and retronasal odor identification in patients with parosmia

“…This possible unequal affection of the ortho- and retronasal mucosa could be tested in studies using biopsies or brushings from the anterior and posterior part of the olfactory mucosa. Other possibilities would be the study of ortho- or retronasal odor thresholds [ 27 ] for parosmigenic odors [ 28 ].…”