Background: Posttraumatic olfactory dysfunction is a clinical challenge due to refractory characteristics and limited therapeutic options. Olfactory training has been proved to be effective for olfactory dysfunction with varied etiologies. We pooled existing studies to evaluate the effects of olfactory training in patients with posttraumatic olfactory dysfunction.Methods: A systematic literature review using PubMed, Embase, Cochrane Library, and Web of Science was conducted to identify studies assessing olfactory change in patients with posttraumatic olfactory dysfunction after olfactory training.Results: Of the initial 812 abstracts reviewed, 13 full‐text articles were included. Clinically significant results after olfactory training were defined as an improvement of threshold, discrimination, and identification (TDI) score ≥6 or University of Pennsylvania Smell Identification Test (UPSIT) score ≥4. Six studies were included in the meta‐analysis, 36.31% (95% confidence interval [CI], 0.28 to 0.45) of posttraumatic patients would achieve clinically significant results after olfactory training with a mean increase of TDI score of 4.61.Conclusion: Olfactory training might be a promising modality for the treatment of posttraumatic olfactory dysfunction. More high‐quality studies with controls are needed to clarify the effect of olfactory training on total olfactory performance and subcomponents of olfaction.

Purpose of Review: Olfactory dysfunction dramatically impairs quality of life with a prevalence of 20% in the general adult population. Psychophysical olfactory testing has been widely used to evaluate the ability to smell due to its validated utility and feasibility in clinic. This review summarizes the current literature regarding psychophysical olfactory testing and the clinical relevance of the olfactory testing with different components. Furthermore, the review highlights the diagnosis and treatment value of olfactory subtests in patients with olfactory dysfunction.Recent Findings: With the accumulation of studies of psychophysical olfactory testing in olfactory disorders, the clinical relevance of olfactory testing with different components is expanding. Different olfactory domains present with distinct olfactory processing and cortical activity. Psychophysical assessment of olfaction with three domains reveals different levels of olfactory processing and might assist with analyzing the pathophysiologic mechanism of the various olfactory disorders. Furthermore, olfactory thresholds provided the largest amount of non-redundant information to the olfactory diagnosis. Sinonasal olfactory dysfunction and non-sinonasal-related olfactory dysfunction are emerging classifications of smell disorders with certain characteristics of olfactory impairment and different responses to the therapy including steroids, sinus surgery, and olfactory training.Summary: These recent advancements should promote the understanding of psychophysical olfactory testing, the association between individual subcomponents and neurophysiological processes, and pave the way for precision assessment and treatment of the olfactory dysfunction.

Background: Acute exacerbations (AE) in chronic rhinosinusitis (CRS) have been increasingly recognized as an important clinical issue. The purpose of this study is to summarize the current definitions and evaluation parameters of AE and then identify and quantify the clinical and immunopathologic characteristics of AE in CRS. Methods: A systematic review of the literature was performed on PubMed, Scopus, and Cochrane databases from January 1990 through August 2020 to identify studies relating to AE in CRS. Exclusion criteria included non-English and non-human studies, and case reports. Results: The definitions of AE in CRS among all the studies were based on a description of short-term worsening sinonasal symptoms. Patient-reported sinus infection and exacerbation related medical treatment during the preceding 3 months to 1 year were used to evaluate the frequency of AE in CRS. The average decline in 22-item Sino-Nasal Outcome Test (SNOT-22) score during an exacerbation was 7.83 points relative to baseline. Comorbid asthma, SNOT-22 scores ≥24, allergic rhinitis, eosinophil count ≥150/μL and autoimmune disease were positively associated with an exacerbation-prone CRS phenotype. AE in chronic rhinosinusitis with nasal polyps (CRSwNP) was associated with increased expression of mucus cytokines including myeloperoxidase (percentage increase [PI] = 101%), IL-5 (PI = 125%), and IL-6 (PI = 162%) and could be predicted by the increasing mucus cystatin and periostin. Conclusion: The definition of AE in CRS is largely driven by patient-reported symptoms and is associated with several risk factors. Quantitative changes in mucus cytokines associated with AE in CRSwNP and may be used to predict events. The development of a consistent definition of AE in CRS is critical to help define disease control and treatment efficacy.

Background: Acute exacerbations of chronic rhinosinusitis (CRS) have been increasingly recognized as an important disease entity with a significant impact on the quality of life. There is a growing amount of research on the etiopathogenesis and management of acute exacerbations of CRS. This review aims to summarize the current literature and provide an overall understanding of acute CRS exacerbations. Methods: A related literature review with the key terms of “chronic rhinosinusitis” and “exacerbation” was performed using PubMed. Results: There is no consensus definition of the acute exacerbation of CRS. Impaired mucociliary clearance, atrophic rhinitis, and immunologic changes are important predisposing factors for acute CRS exacerbations. Current evidence supports the role of the transient viral infection as the initial inflammatory stimulus in the pathogenesis of acute CRS exacerbations. Secondary bacterial infection or microbial community dysbiosis within the sinonasal cavity is the main event during the acute exacerbation of CRS. Distinct changes in local and systemic immune responses during exacerbation provide new insights into the pathophysiology of CRS exacerbation. Although current guidelines suggest the use of short-term antibiotics in patients with acute CRS exacerbation for symptomatic relief, evidence-based treatment recommendations for acute CRS exacerbation are still lacking, and large-high-quality RCTs are required. Conclusion: There have been significant advances in understanding the etiology and immunological feathers of acute CRS exacerbation. Nevertheless, consensus definition, diagnostic criterion, biomarkers to differentiate acute CRS exacerbation from CRS, assessment of disease severity, and evidence-based treatment options for acute CRS exacerbation are still lacking.