Difficulties with Odor Recognition Threshold Measurement Methods in T&T Olfactometry as Reported by Patients: A Survey

Abstract

　　Olfaction tests are essential for evaluating the function of the sense of smell. In T&T olfactometry, the detection threshold is measured from the concentration at which an odor is perceived, the recognition threshold is measured from the concentration at which description of the kind of odor is possible, and the degree of olfactory impairment is determined from the average of five different recognition thresholds. According to the clinical practice guidelines for the management of olfactory dysfunction, patients may have trouble describing smells; however, the actual manner by which patients perceive smells remains unclear. This study sought to elucidate patients' opinions and problems with the odor recognition threshold test in T&T olfactometry. A survey was conducted among patients who had undergone T&T olfactometry between April 2022 and March 2023. An odor recognition threshold test was presented with the olfactory term table to aid patients who struggle to describe the odor. The study included 125 patients. Among these patients, 20.2% and 50.8% had severe and moderate difficulty in describing smells, respectively. About 50.4% of the patients indicated that they needed to make a choice. The higher the difficulty in describing the odor, the higher the difference between the cognitive and detection thresholds increased, and the longer the test time was prolonged. In the recognition threshold test in T&T olfactometry, several patients struggled to describe smells. Standardization of the method of presenting the olfactory term table will contribute to more accurate testing and inspection operations.