Olfactory dysfunction in patients with chronic rhinosinusitis

Overview

Introduction: Chronic rhinosinusitis (CRS) is one of the most common causes of olfactory dysfunction. Despite available therapeutic options, treatment does not always result in complete recovery. Olfactory dysfunction in CRS arises from a combination of predominantly conductive and sensorineural mechanisms, with a significant role of type 2 inflammation. Olfactory assessment includes subjective questionnaires and psychophysical tests enabling evaluation of treatment effects, as well as objective olfactometric methods (e.g., olfactory evoked potentials). Materials and methods: A prospective observational study was conducted from October 1, 2022 to July 31, 2025 in a total of 119 patients divided into three groups: patients with chronic rhinosinusitis without nasal polyps (CRSsNP) indicated for functional endoscopic sinus surgery (FESS) (N = 33), patients with chronic rhinosinusitis with nasal polyps (CRSwNP) indicated for FESS (N = 65), and patients with CRSwNP after FESS receiving biologic therapy with omalizumab (Xolair®) (N = 21). Assessments were performed before treatment (in group 3 during biologic therapy) and after three months. Primary outcomes included changes in olfactory threshold measured by Sniffin’ Sticks (OT –⁠ threshold test) and the Odorized Marker Test (OMT); secondary outcomes included changes in SNOT-22 scores. OT interpretation was based on age -⁠ and sex-specific normative data (10th percentile), and a decrease of ≥ 8.9 points in SNOT-22 was considered the minimal clinically important difference. Results: After FESS, improvement in olfactory threshold was observed (CRSsNP: OT 2.95 → 4.44; CRSwNP: OT 2.52 → 3.74), along with a shift toward normosmia according to OMT and a reduction in SNOT-22 scores. Biologic therapy led to improvement in OMT (4.24 → 6.14) and a decrease in SNOT-22 scores (27.24 → 17.05). Conclusion: Psychophysical tests and the SNOT-22 questionnaire reliably assess the benefit of both surgical and biologic treatment of CRS on olfactory function and quality of life.