Olfactory Dysfunction in Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a prevalent and heterogeneous inflammatory disease that affects millions of people worldwide. Olfactory dysfunction (OD) is one of the most common symptoms of CRS patients. Increasing evidence suggests that the mechanisms underlying OD in different clinical subtypes and inflammatory endotypes of CRS may show discrepancy. Additionally, assessing the severity of OD in CRS patients, and selecting appropriate and effective treatment approaches have emerged as critical concerns in clinical practice. This article aims to provide new insights into the pathogenesis, diagnosis and treatment of OD in patients with CRS.

Recent studies have further highlighted the heterogeneity of CRS, categorizing it into Type 2 and non-Type 2 subtypes based on distinct inflammatory patterns. Furthermore, the diverse mechanisms of OD in patients with different subtypes of CRS have been revealed. Beyond the conventionally recognized conductive factors, inflammatory factors are increasingly being identified as crucial pathogenic contributors to OD in patients with CRS. Generally, the evaluation methods for OD mainly include three different categories, including self-reported assessments based on questionnaires or scales, psychophysical tests, and electrophysiological or imaging assessments. Despite considerable efforts on new approaches, the long-term and effective treatments of OD in CRS still remain elusive. Olfactory training (OT) can be recommended for patients with OD, although it requires further evaluation in CRS patients.

This article, based on recent progress, overviewed the epidemiological characteristics and pathophysiological mechanisms of OD in CRS patients, and summarized the methods of clinical assessment and treatment strategies of OD. We emphasized the diverse mechanisms of OD in different subtypes of CRS. Although drugs, biological products, and OT may be beneficial for improving olfactory function in CRS patients, further research is needed to confirm their long-term efficacy and develop more effective treatment approaches for OD in CRS.