Olfactory cleft and sinus opacification differentially impact olfaction in chronic rhinosinusitis

Olfactory cleft stenosis and obstruction on paranasal sinus CT scan in pre-septo-rhinoplasty patients: normal variants or pathologic findings?

OBJECTIVE(S)

To determine the frequency of olfactory cleft (OC) stenosis and obstruction on paranasal sinus CT scans in pre-septorhinoplasty of patients who had septal deviation, septopyramidal deformation or nasal obstruction without other sinonasal conditions.

METHODS

This retrospective study included patients referred to our institution between December 2013 and December 2021 for septorhinoplasty due to nasal obstruction without other sinonasal or neurological conditions. All patients underwent preoperative paranasal sinus CT scan and olfactory testing. OC stenosis was quoted as none, partial, or total (less than 1/3 contact between nasal septum and ethmoid turbinates, 1/3-2/3, more than 2/3, respectively), as well as OC obstruction as none, partial, or complete (obstruction of less than 1/3 of OC, 1/3-2/3, more than 2/3, respectively). Radiologic evaluation was validated by near perfect interobserver agreement.

RESULTS

A total of 75 patients (32 women, 43 men) with a mean age of 44.2 ± 15.64 (23-74) years were included, of which 36 were normosmic and 39 hyposmic. OC stenosis was partial in 58.7% (n = 44) of the patients, absent in 28% (n = 21), and total in 13.3% (n = 10), without difference between normosmic and hyposmic patients (p = .66). OC obstruction was absent in 52% (n = 39) and partial in 46.7% (n = 35), without difference between normosmic and hyposmic patients (p = .51). Only one normosmic patient had complete OC obstruction.

CONCLUSION

OC partial stenosis and partial obstruction were frequent findings in pre-septorhinoplasty patients without respiratory mucosa disease and did not influence their olfactory status. Total stenosis and complete obstruction were rarer and require further investigation.

CLINICAL RELEVANCE STATEMENT

Isolated partial olfactory cleft stenosis and obstruction should be considered normal variants, whereas the impact of complete olfactory cleft stenosis and obstruction on patient's olfactory status remains to be determined.

KEY POINTS

• The incidence of olfactory cleft stenosis and obstruction in asymptomatic patients remains unknown, even though it is encountered in clinical practice. • Partial and total olfactory cleft stenosis occurred in 58.7% and 13.3% of the patients; partial obstruction occurred in half of the cases, but complete obstruction was extremely rare. • There are frequent findings of partial olfactory cleft obstruction and stenosis, but complete obstruction and total stenosis should be further investigated.

Propriety of various examinations for subjective symptoms of olfactory disorders

PURPOSE

In Japan, two types of tests for diagnosing olfactory disorders, T and T (T&T) olfactometry and intravenous olfactory tests, are covered by insurance and performed on patients with olfactory disorders. This study examined the validity of these olfactory tests and whether psychophysical or morphological tests are more helpful in evaluating olfactory disorders.

METHODS

We evaluated patients who visited our department and underwent two types of olfaction tests and sinus computed tomography (CT). Data regarding the age, sex, peripheral blood eosinophil percentage, presence of bronchial asthma, diagnoses, olfactory symptom score, results of the two olfactory tests, and CT findings in eligible patients were extracted from medical records and retrospectively reviewed.

RESULTS

One hundred and sixty-three patients underwent all tests during the study period. The results of the T&T olfactometry and intravenous olfactory tests were significantly correlated. However, only the results of T&T olfactometry and olfactory cleft opacification on CT were statistically significant predictors of the olfactory symptom scores.

CONCLUSION

T&T olfactometry and CT evaluations of olfactory cleft opacification helped evaluate olfactory dysfunction. It is important to note that intravenous olfactory tests are best performed with careful control and not blindly to assess olfactory disorders.

Utilization of RNA sequencing to investigate olfactory dysfunction in chronic rhinosinusitis without nasal polyps: A pilot study

Objectives

Prior research on olfactory dysfunction in chronic rhinosinusitis (CRS) has focused on patients with polyps and suggests that direct inflammation of the olfactory cleft mucosa plays a contributory role. The purpose of this study was to evaluate gene expression in superior turbinate mucosal specimens, comparing normosmic and dysosmic CRS patients without polyps (CRSsNP).

Methods

Tissue samples were obtained from the superior turbinates of patients with CRSsNP at the time of endoscopic sinus surgery. Samples subsequently underwent RNA sequencing and functional analysis to investigate biological pathways associated with differentially expressed genes between dysosmic (n = 7) and normosmic (n = 4) patients.

Results

Differential gene expression analysis comparing dysosmic and normosmic CRSsNP patients showed upregulation of 563 genes and downregulation of 327 genes. Using stringent criteria for multiple comparisons, one upregulated gene (Immediate Early Response 3 [IER3]) had an false discovery rate (FDR) correction adjusted P value considered statistically significant (P < 0.001, fold change 2.69). Reactome functional analysis revealed eight biological pathways significantly different between dysosmic and normosmic patients (P < 0.05, FDR correction) including IL-4 and IL-13 signaling, IL-10 signaling, and rhodopsin-like receptors.

Conclusions

RNA sequencing of the superior turbinates in patients with CRSsNP can provide valuable information regarding biological pathways and genes involved in olfactory dysfunction. This study supports literature suggesting that Type 2 inflammation may play a role in olfactory dysfunction in at least some patients with CRSsNP. This study also prompts questions regarding the role of IL-10, rhodopsin-like receptors, and IER3 in the pathogenesis of olfactory dysfunction.

Chronic rhinosinusitis in the era of CFTR modulator therapy

Chronic rhinosinusitis is a common manifestation of CF that is associated with impaired quality of life and can be difficult to treat. CFTR modulator therapy has resulted in significant improvements in lower respiratory and nutritional outcomes for people with CF however their impact on chronic rhinosinusitis has received less attention. We review the literature in relation to chronic rhinosinusitis in CF and examine the impact of CFTR modulator therapy on symptoms, imaging, endoscopic appearances, and olfactory outcomes in the treatment of chronic rhinosinusitis. While an overall improvement in symptoms, imaging and endoscopic appearances is seen in response to treatment, limited impact is documented on olfaction. Outcome measures employed were heterogenous, limiting comparison of findings. There is a need for well powered prospective real-world studies with standardised outcome measures.

Impact of Nasal Cavity CT Opacification Upon Sinonasal Quality of Life

BACKGROUND

Current methods of quantifying inflammation in chronic rhinosinusitis (CRS) on computed tomography (CT) imaging focus on opacification of the paranasal sinuses and show limited correlation with patient-reported outcome measures.

OBJECTIVE

This study aimed to determine if quantifying CT opacification of the nasal cavity correlated with Sino-Nasal Outcomes Test scores (SNOT-22).

METHODS

Thirty patients with CRS were enrolled. Lund-Mackay and SNOT-22 scores were measured. Nasal cavity regions of interest (ROIs) were measured by 2 independent raters using ImageJ at 3 points on coronal CT scans: anteriorly at the lacrimal duct, at the approximate midpoint demarcated by the posterior aspect of the globe, and posteriorly at the transition from the hard to soft palate. Superior and inferior regions were defined based upon the root of the inferior turbinate. Percent opacification was calculated for each ROI. Analyses were conducted bilaterally and for the side with greater opacification (worse side).

RESULTS

Interrater reliability was strong for all ROIs. Lund-Mackay scores correlated with nasal blockage only (r = .495, P = .01) and did not correlate with nasal cavity ROI opacification. Inferior nasal cavity opacification for worse-sided anterior ROI and middle ROI correlated with SNOT-22 scores for nasal blockage (anterior r = .41, P = .03) (middle r = .42, P = .023) and runny nose (anterior r = .44, P = .02) (middle r = .38, P = .04). Posterior ROIs did not correlate with SNOT-22.

CONCLUSIONS

Traditional CT scoring of sinus opacification does not correlate well with nasal cavity opacification or SNOT-22. Inferior nasal cavity inflammation provides unique correlations with SNOT-22 nasal questions and may guide targeted interventions in these regions.

Olfactory cleft mucus galectin-10 predicts olfactory loss in chronic rhinosinusitis

BACKGROUND

Eosinophils have been reported to be involved in the pathogenesis of olfactory fluctuation in chronic rhinosinusitis (CRS). Galectin-10 is more frequently associated with type 2 inflammation and potentially a sign of intense eosinophil activation.

OBJECTIVE

To explore olfactory cleft mucus and olfactory mucosa galectin-10 level and its association with olfactory dysfunction (OD) in CRS.

METHODS

We prospectively enrolled 50 patients with CRS and 15 healthy controls. Olfactory cleft mucus and superior turbinate biopsy specimens were collected to analyze galectin-10 levels and quantify tissue eosinophils. Psychophysical olfactory testing, olfactory cleft endoscopy scale, and olfactory cleft computed tomography scores were obtained. The predictability of galectin-10 levels for OD in patients with CRS was analyzed by multivariable logistic regression analysis.

RESULTS

Both olfactory cleft mucus and olfactory mucosa galectin-10 levels in patients with CRS with OD were significantly higher than those in patients with CRS without OD (all P < .001). Mucus galectin-10 levels were positively correlated with tissue eosinophils (r = 0.541, P = 0.002), olfactory cleft endoscopy scale (r = 0.498, P = 0.006), and olfactory cleft computed tomography scores (r = 0.432, P = 0.019) in patients with CRS. Mucus galectin-10 levels were negatively correlated threshold, discrimination, and identification (r = -0.589,  P = 0.001), olfactory threshold (r = -0.522, P = 0.003), olfactory discrimination (r = -0.488, P = 0.007), and olfactory identification (r = -0.466, P = 0.011) scores. After adjusting for patient demographics and comorbidities, mucus galectin-10 levels were significantly associated with OD in patients with CRS (odds ratio, 1.299; P = .008). Mucus galectin-10 levels greater than 8.975 ng/mL were the best predictor of OD in CRS.

CONCLUSION

Olfactory cleft mucus galectin-10 is highly associated with OD in CRS.

Olfaction Now and in the Future in CRSwNP

BACKGROUND

Chronic rhinosinusitis (CRS) is the leading cause of olfactory dysfunction in the general population. Olfactory dysfunction is more common in patients with CRS with nasal polyposis (CRSwNP) compared to those without polyps.

PURPOSE

The present review aims to summarize the current literature on the mechanism behind olfactory dysfunction in CRSwNP and the impact of therapy on olfactory outcomes in this patient population.

METHODS

A comprehensive review of the available literature on olfaction in CRSwNP was performed. We evaluated the most recent evidence from studies on the mechanisms behind smell loss in CRSwNP and the impact of medical and surgical therapy for CRS on olfactory outcomes.

RESULTS

The mechanism behind olfactory dysfunction in CRSwNP is not completely understood, but evidence from clinical research and animal models suggests both an obstructive component causing conductive olfactory loss and an inflammatory response in the olfactory cleft leading to sensorineural olfactory loss. Oral steroids and endoscopic sinus surgery have both shown efficacy in improving olfactory outcomes in CRSwNP in the short term; however, the long-term response of these treatments remains uncertain. Newer targeted biologic therapies, such as dupilumab, have also shown remarkable and durable improvement in smell loss for CRSwNP patients.

CONCLUSION

Olfactory dysfunction is highly prevalent in the CRSwNP population. Although significant advances have been made in our understanding of olfactory dysfunction in the setting of CRS, additional studies are needed to elucidate cellular and molecular changes mediated by type 2-mediated inflammation in the olfactory epithelium with potential downstream effects on the central olfactory system. Further identification of these underlying basic mechanisms will be vital for developing future therapies targeted to improve olfactory dysfunction in patients with CRSwNP.

Association of computed tomography scores to psychophysical measures of olfaction: A systematic review and meta-analysis

BACKGROUND

While various sinus computed tomography (CT) scoring systems have been proposed and used in the literature, no single system has been identified as superior. The strength of associations between CT scoring systems and measures of olfaction also remains unclear.

METHODS

A systematic review of PubMed, CINAHL, Scopus, and the Cochrane Library was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies that reported both CT scores and measures of olfaction in a cross-sectional manner were included.

RESULTS

A total of 37 studies were eligible for meta-analysis. Of 8035 patients with chronic rhinosinusitis, 55.6% were male patients and 53.2% had chronic rhinosinusitis with nasal polyps. Analysis by meta-regression was performed of Lund-Mackay (LM) versus Smell Identification Test-40 (SIT-40; 12 studies), Brief Smell Identification Test (BSIT; 10 studies), Sniffin' Sticks (SS; 10 studies), and Toyota & Takagi (T&T) olfactometry (four studies). A significant moderate association was found between LM and SIT-40 (R²  = 0.612, p < 0.001) and LM and SS (R²  = 0.612, p < 0.001). An association between LM and BSIT approached significance (R²  = 0.461, p = 0.054). No significant associations were noted between LM and T&T olfactometry and between LM and SS when stratified by nasal polyp status.

CONCLUSION

There is a significant moderate association of current CT scoring systems to SIT-40 and SS. Further research should focus on associations of objective measures of olfaction to CT scores of the nasal cavity, sinuses, and olfactory cleft, as well as other disease markers.

Clinically meaningful changes in efficacy outcomes in chronic rhinosinusitis with nasal polyposis

PURPOSE OF REVIEW

Chronic rhinosinusitis with nasal polyps (CRSwNP) carries a high disease burden, and many studies have been done investigating the efficacy of various medical and surgical therapies. However, outcome metrics have varied across these studies, making it difficult to compare therapeutic efficacy on a large scale. In this article, we discuss various outcome metrics used across prior studies as well as the relationship between these measures.

RECENT FINDINGS

Outcome metrics in CRSwNP studies include both clinically assessed and patient-reported outcome measures (PROMs). The former includes olfaction testing, scoring systems based on imaging and endoscopic evaluation, and histopathological and immunohistochemical evaluation of sinus tissue, and the latter includes quality-of-life instruments, symptom severity scales, and disease-control instruments. Recent studies evaluating the efficacy of new biologics have used a combination of both types of metrics.

SUMMARY

Both clinical metrics and patient-reported outcomes provide utility in evaluating disease severity and control in patients with CRSwNP, although there are nuances when comparing therapies in this population as patients with CRSwNP are heterogeneous and may have symptoms across several domains. However, PROMs in conjunction with clinical metrics provide useful information to assess patient symptoms and response to interventions.

Predictive significance of the questionnaire of olfactory disorders-negative statements for olfactory loss in patients with chronic rhinosinusitis

Objectives

The questionnaire of olfactory disorder-negative statements (QOD-NS) is a valid and reliable instrument for assessing the olfactory-specific quality of life. This study aimed to explore the association between the QOD-NS and objective olfactory metrics (including objective olfactory cleft assessment) and then evaluate the predictive significance of the QOD-NS for olfactory loss in Chinese patients with chronic rhinosinusitis (CRS).

Methods

A total of 70 patients with CRS were enrolled in the study. Olfaction was assessed with Sniffin’ Sticks. The olfactory cleft was assessed by the sinus CT scan and nasal endoscopy (the Lund–Mackay olfactory cleft scale, LM-OC and olfactory cleft endoscopy scale, OCES). The QOD-NS and its short version were utilized to assess the patient-reported olfaction. The predictors associated with olfactory loss were analyzed by the logistic regression analysis. The optimal cutoff points of the predictors were determined by the receiver-operating characteristic curves and the Youden index.

Results

The TDI score in patients with CRS significantly correlated with the QOD-NS (r = − 0.755, P < 0.001), OCES (r = − 0.520, P < 0.001), LM-OC (r = − 0.615, P < 0.001). After adjusting for patient demographics and comorbidities, QOD-NS was significantly associated with olfactory dysfunction [odds ratio (OR) = 1.243; P = 0.001] and anosmia in patients with CRS (OR = 1.838; P = 0.006). Furthermore, the QOD-NS significantly correlated with the LM-OC (r = 0.610, P < 0.001), and the OCES (r = 0.464, P < 0.001) in patients with CRS. The QOD-NS had the highest predictive value for olfactory dysfunction (optimal cutoff = 10.5; Youden index = 0.635; area under the curve = 0.861) and anosmia (optimal cutoff = 20.5; Youden index = 0.790; area under the curve = 0.928) in patients with CRS.

Conclusion

The QOD-NS showed high validity and correlated well with objective olfactory metrics and olfactory cleft assessment in patients with CRS. The QOD-NS was a reliable predictor for olfactory dysfunction and anosmia in patients with CRS, which may aid in the fast screening of olfactory loss in the clinic.

[Application research and development of objective examination of olfactory function]

The sense of smell is one of the five most primitive human sensory functions, and it plays a very important role in our daily lives. Despite numerous methods for evaluating olfactory function, there is still a lack of standardization of olfactory tests and the results are often inconsistent. Furthermore, the related research on objective evaluation started relatively late. Along with the deciphering of the olfactory pathway, the technical level of olfactory objective inspection has been greatly improved and significant progress has also been made in terms of clinical application, such as: olfactory pathway MRI and fMRI imaging, OERPs, BEAM for various olfactory disorders and early diagnosis of neurodegenerative disorders, as well as related research based on bionic olfactory sensing technology. This article mainly introduces the recent research progress of several commonly used objective olfactory tests and provides reference for more accurate evaluation of olfactory function.

COVID-19 and rhinological surgery

The Coronavirus-19 (COVID-19) pandemic has caused disruptions in the normal patient care workflow, necessitating adaptations within the healthcare profession. The objective of this article is to outline some of these adaptations and considerations necessitated by COVID-19 within the subspeciality of rhinology and endoscopic skull base surgery.

Clinical Assessment of Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a common disease that affects >10% of the adult population in Europe and the United States. It has been delineated phenotypically into CRS without nasal polyps and CRS with nasal polyps. Both have a high disease burden and an overlapping spectrum of symptoms such as nasal obstruction, olfactory dysfunction, facial pain, pressure, and nasal discharge. Primary assessment includes evaluation of patient symptoms and impact on quality of life, nasal endoscopic examination, and imaging. Significant progress has been made in the understanding of CRS pathophysiology. There is a move toward describing CRS in terms of the predominant endotype or inflammatory pattern pathomechanism rather than the traditional classification of patients with and without nasal polyps. An increased elucidation of the disease endotypes, as characterized by their inflammatory pathways and mediators, is leading to a tailored more personalized treatment approach to the different disease subtypes.

International consensus statement on allergy and rhinology: Olfaction

BACKGROUND

The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).

METHODS

Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.

RESULTS

The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.

CONCLUSION

This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Olfactory Outcomes with Dupilumab in Chronic Rhinosinusitis with Nasal Polyps

BACKGROUND

Loss of smell (LoS) is one of the most troublesome and difficult-to-treat symptoms of severe chronic rhinosinusitis with nasal polyps (CRSwNP).

OBJECTIVE

To assess the impact of dupilumab on sense of smell in severe CRSwNP.

METHODS

In the randomized SINUS-24 and SINUS-52 studies, adults with severe CRSwNP received dupilumab 300 mg subcutaneously or matching placebo every 2 weeks for 24 or 52 weeks, respectively. Smell was assessed using daily patient-reported LoS score (0-3) and University of Pennsylvania Smell Identification Test (UPSIT; 0-40). Data from the 2 studies were pooled through week 24. Relationships between patient phenotypes and smell outcomes were also assessed.

RESULTS

We randomized 724 patients (286 placebo, 438 dupilumab); mean CRSwNP duration was 11 years; 63% had prior sinonasal surgery. Mean baseline LoS was 2.74. Dupilumab produced rapid improvement in LoS, evident by day 3, which improved progressively throughout the study periods (least squares mean difference vs placebo -0.07 [95% CI -0.12 to -0.02]; nominal P < .05 at day 3, and -1.04 [-1.17 to -0.91]; P < .0001 at week 24). Dupilumab improved mean UPSIT by 10.54 (least squares mean difference vs placebo 10.57 [9.40-11.74]; P < .0001) at week 24 from baseline (score 13.90). Improvements were unaffected by CRSwNP duration, prior sinonasal surgery, or comorbid asthma and/or nonsteroidal anti-inflammatory drug-exacerbated respiratory disease. Baseline olfaction scores correlated with all measured local and systemic type 2 inflammatory markers except serum total immunoglobulin E.

CONCLUSIONS

Dupilumab produced rapid and sustained improvement in sense of smell, alleviating a cardinal symptom of severe CRSwNP.

Olfactory dysfunction in cystic fibrosis: Impact of CFTR modulator therapy

BACKGROUND

Elexacaftor-tezacaftor-ivacaftor (ETI) improves pulmonary health and chronic rhinosinusitis (CRS) for people with cystic fibrosis (PwCF), however its impact on olfaction has not been investigated. Olfactory dysfunction impairs quality-of-life (QOL). This study evaluated the impact of ETI on multiple olfactory metrics.

METHODS

Adult PwCF/CRS with CF transmembrane conductance regulator genotype F508del/F508del or F508del/minimal function who clinically initiated ETI participated in a prospective, observational study. Endpoints included changes after 6 months of ETI in quantitative olfactory function (Smell Identification Test, SIT), olfactory QOL (Questionnaire of Olfactory Disorders, QOD) and percent olfactory cleft opacification (%OCO), representing superior nasal cavity inflammation where afferent olfactory neurons are concentrated.

RESULTS

30 PwCF/CRS met inclusion criteria; 25 completed the study. Mean ETI adherence was 93%. At baseline, participants were hyposmic (mean SIT 31.3), had significant %OCO (mean 65.6%), yet reported non-impaired olfactory QOL (mean QOD 6.1). At follow-up, mean SIT worsened mildly (p=0.009), mean %OCO remained stable (p=0.46), and mean QOD improved modestly (p=0.008). No outcomes were impacted by prior modulator use, genotype, nasal polyps, or CF-related diabetes. Prior sinus surgery was associated with QOD improvement (p=0.04). Increased (worse) baseline QOD scores and %OCO were associated with greater improvements (p<0.003), but not SIT (p=0.44).

CONCLUSIONS

ETI was not associated with improvement in quantitative olfaction or olfactory cleft opacification after 6 months. PwCF/CRS have hyposmia but do not report impairment in olfactory QOL. Further study to investigate mechanisms explaining olfactory dysfunction and whether olfaction improves with greater duration of ETI or in younger age groups is warranted.

The temporal course of COVID-19 anosmia and relation to other clinical symptoms

OBJECTIVE

This study aimed to define the clinical course of anosmia in relation to other clinical symptoms.

METHODS

135 patients with COVID-19 were reached by phone and subsequently included in the study. Olfactory functions were evaluated using a questionnaire for assessment of self-reported olfactory function. Patients were divided into four subgroups according to the presence of olfactory symptoms and temporal relationship with the other symptoms: group1 had only olfactory complaints (isolated, sudden-onset loss of smell); group2 had sudden-onset loss of smell, followed by COVID-19 related complaints; group3 initially had COVID-19 related complaints, then gradually developed olfactory complaints; and group4 had no olfactory complaints.

RESULTS

In total, 59.3% of the patients interviewed had olfactory complaints during the disease course. The olfactory dysfunction severity during COVID-19 infection was significantly higher in group1 compared to groups 2 and 3. In groups1-3, the odor scores after recovery from COVID-19 disease were significantly lower compared to the status prior to disease onset. The residual olfactory dysfunction was similar between groups1 and 2, but was more evident than group3. Mean duration for loss of smell was 7.8 ± 3.1 (2-15) days. Duration of loss of smell was longer in groups1 and 2 than in group3. Odor scores completely returned back to the pre-disease values in 41 (51.2%) patients with olfactory dysfunction. Rate of complete olfactory dysfunction recovery was higher in group3 compared to groups1 and 2.

CONCLUSION

In isolated anosmia cases, anosmia is more severe, and complete recovery rates are lower compared to the patients who have other clinical symptoms.

LEVEL OF EVIDENCE

Level 4.

A systematic review to examine the relationship between objective and patient-reported outcome measures in sinonasal disorders: recommendations for use in research and clinical practice

BACKGROUND

Common sinonasal disorders include chronic rhinosinusitis (CRS), allergic rhinitis (AR), and a deviated nasal septum (DNS), which often coexist with shared common symptoms including nasal obstruction, olfactory dysfunction, and rhinorrhea. Various objective outcome measures and patient-reported outcome measures (PROMs) are used to assess disease severity; however, there is limited evidence in the literature on the correlation between them. This systematic review aims to examine the relationship between them and provide recommendations.

METHODS

A search of MEDLINE and EMBASE identified studies quantifying correlations between objective outcome measures and PROMs for the sinonasal conditions using a narrative synthesis.

RESULTS

In total, 59 studies met inclusion criteria. For nasal obstruction, rhinomanometry shows a lack of correlation whereas peak nasal inspiratory flow (PNIF) shows the strongest correlation with PROMs (r > 0.5). The Sniffin' Stick test shows a stronger correlation with PROMs (r > 0.5) than the University of Pennsylvania Smell Identification Test (UPSIT) (r < 0.5). Computed tomography (CT) sinus scores show little evidence of correlation with PROMs and nasal endoscopic ratings (weak correlation, r < 0.5).

CONCLUSION

Overall, objective outcome measures and PROMs assessing sinonasal symptoms are poorly correlated, and we recommend that objective outcome measures be used with validated PROMs depending on the setting. PNIF should be used in routine clinical practice for nasal obstruction; rhinomanometry and acoustic rhinometry may be useful in research. The Sniffin' Sticks test is recommended for olfactory dysfunction with UPSIT as an alternative. CT scores should be excluded as a routine CRS outcome measure, and endoscopic scores should be used in combination with PROMs until further research is conducted.

Olfactory cleft mucus inflammatory proteins in CRS: a case-control study

BACKGROUND

Multiple hypotheses are evolving that suggest several, potentially overlapping etiologies for olfactory dysfunction (OD) in chronic rhinosinusitis (CRS). Understanding inflammatory cytokine profiles of the olfactory cleft (OC) and their association with olfactory function is foundational for future clinical care and research.

METHODS

This cross-sectional, case-control study evaluates associations among OC mucus inflammatory proteins, psychophysical olfactory testing, and computed tomography (CT) analysis of the OC and sinuses. Normative reference intervals were determined for each protein and odds ratios (ORs) were used to compare proportions of altered expression between CRS without nasal polyposis (CRSsNP) and CRS without nasal polyposis (CRSwNP).

RESULTS

Case subjects with CRS (n = 151) and controls (n = 74) were evaluated. A majority of OC proteins tested were found within detectable ranges for cases and controls. The CRS cohort had significantly higher concentrations for 23 of 26 proteins. CRS cases with abnormal levels of C-C motif chemokine ligand 2 (CCL2), CCL3, interleukin 5 (IL5), IL10, and IL13 associated with greater olfactory deficits. The prevalence of elevated IL5 and IL13 in anosmic patients was 64.6% and 62.5%, respectively (p < 0.004). CRS cases with the highest odds of elevated expression in CRSwNP were IL5 (OR = 10.83) and IL13 (OR = 8.36). However, both IL5 and IL13 were still elevated in approximately 14% of CRSsNP patients. The highest magnitude of correlation between the total percent of OC opacification was found to be with IL5 (r = 0.543; p < 0.001), whereas other moderate correlations were noted with immunoglobulin E (IgE), IL10, and IL13.

CONCLUSION

This study confirmed that OC inflammatory proteins vary both by disease phenotype and in their association with OD. Type 2 inflammatory mediators are increased in CRS, especially within the CRSwNP group. However, a substantial proportion of CRSsNP also express type 2 inflammatory mediators. Further research is necessary to understand the complex roles OC mucous inflammatory proteins might play in defining endotype and in impacting CRS-related OD. ©2021 ARSAAOA, LLC.

Endotyping chronic rhinosinusitis based on olfactory cleft mucus biomarkers

BACKGROUND

Although chronic rhinosinusitis (CRS) is considered the most treatable form of olfactory dysfunction, there has been relatively little clinical attention focused on assessing endotypes as they pertain to olfactory loss.

OBJECTIVES

The goal of this study was to explore inflammatory endotypes in CRS using an unsupervised cluster analysis of olfactory cleft (OC) biomarkers in a phenotype-free approach.

METHODS

Patients with CRS were prospectively recruited and psychophysical olfactory testing, Questionnaire of Olfactory Dysfunction (QOD-NS), and bilateral OC endoscopy were obtained. Mucus was collected from the OC and evaluated for 26 biomarkers using principal component analysis. Cluster analysis was performed using only OC biomarkers and differences in olfactory measures were compared across clusters.

RESULTS

A total of 198 subjects (128 with CRS and 70 controls) were evaluated. Evaluation of OC biomarkers indicated 6 principal components, explaining 69.50% of the variance, with type 2, mixed type 1/T_h17-cell, growth factor, and neutrophil chemoattractant inflammatory signatures. A total of 10 clusters were identified that differed significantly in frequency of controls, and subjects with CRS with nasal polyps, and subjects with CRS without nasal polyps across the clusters (likelihood ratio test, χ₁₈²=178.64; P < .001). Olfactory measures differed significantly across clusters, including olfactory testing, QOD-NS, and OC endoscopy (P < .001 for all).

CONCLUSIONS

Clustering based solely on OC biomarkers can organize patients into clinically meaningful endotypes that discriminate between subjects with CRS and controls. Validation studies are necessary to confirm these findings and further refine olfactory endotypes.

Olfactory cleft mucus proteome in chronic rhinosinusitis: a case-control pilot study

BACKGROUND

Mechanisms of smell loss in chronic rhinosinusitis (CRS) are still unclear and likely multifactorial. Little attention has been given to olfactory cleft (OC) mucus proteins involved in odorant binding and metabolizing enzymes and their potential role in smell loss.

METHODS

Mucus from the OC was sampled from patients with CRS (n = 20) and controls (n = 10). Liquid chromatography and mass spectrometry were performed, followed by data processing so that protein groups could be identified, quantified, and compared. Hierarchical clustering and bioinformatic analysis were performed on significantly different proteins to explore for enrichment in known biologic pathways.

RESULTS

A total of 2514 proteins were found in OC mucus from all 30 subjects. Significant differences in protein abundance were found between CRS and controls, including both CRSsNP (n = 351 proteins; log₂ fold change range: -3.88 to 6.71) and CRSwNP (n = 298 proteins; log₂ fold change range: -4.00 to -6.13). Significant differences were found between patients with normosmia and those with dysosmia (n = 183; log₂ fold change range: -3.62 to -2.16) and across groups of interest for a number of odorant binding proteins and metabolizing enzymes.

CONCLUSION

OC mucous in CRS displays a rich and abundant array of proteins, many of which have been implicated in odorant transport and metabolization in animal studies. Significant differences in the olfactory mucus proteome were seen between CRS subtypes and controls, as well as between those with normal and abnormal olfaction. Further study should confirm these findings and explore the role individual proteins play in odorant transport and metabolization. ©2020 ARSAAOA, LLC.

Olfaction: Sensitive indicator of inflammatory burden in chronic rhinosinusitis

BACKGROUND AND OBJECTIVE

Olfactory dysfunction has a high prevalence in chronic rhinosinusitis (CRS) patients and significantly affects quality of life. CRS is recognized as a complex disorder encompassing heterogeneous inflammatory processes in the nose and paranasal sinuses. Olfactory dysfunction in CRS patients is associated with the level of inflammatory mediators and the efficiency of inflammatory control. Learning about the association between CRS-related inflammation and olfactory function will provide clues to the pathogenesis of CRS.

STRUCTURE

The first section of this review describes the assessment of olfactory function using various measures, from ratings to MR based imaging. Then, we discuss the conductive and inflammatory mechanisms related to olfactory dysfunction in CRS: olfaction is associated with certain inflammatory patterns and is potentially a marker of CRS subtype. Finally, we review anti-inflammatory therapies including conservative and surgical approaches, and their effectiveness in olfactory dysfunction in CRS.

CONCLUSION

Assessment of olfactory function should be considered in the clinical evaluation of CRS patients, not only for detecting and quantifying patients' symptom, but also because it appears to be useful to objectively assess the efficacy of CRS treatment over time. In addition, olfaction can be expected to expand the library of CRS phenotypes and endotypes and, hence, pave the way for more precise, tailored treatment options.

Radiological Markers of the Olfactory Cleft: Relations to Unilateral Orthonasal and Retronasal Olfactory Function

The opacification of the olfactory cleft (OC) has been associated with birhinal orthonasal olfaction in patients with chronic rhinosinusitis (CRS). The aim of this study was to determine the associations between monorhinal and birhinal orthonasal, and retronasal olfaction with radiological markers of the OC in a cohort of patients with CRS. Results were analyzed in a CRS-cohort including 13 patients with nasal polyposis (CRSwNP) and 12 patients with non-eosinophilic CRS (non-eCRS). Monorhinal and birhinal orthonasal olfactory function, and OC-air volume were higher in non-eCRS compared CRSwNP. OC-opacification was also higher in CRSwNP compared to non-eCRS. In the entire CRS-cohort, those with higher OC-opacification showed significantly lower orthonasal and retronasal olfactory test results compared to those with lower OC-opacification across all three coronal planes. Similarly, higher unilateral OC-opacification was also associated with lower ipsilateral orthonasal olfactory function. Correlation analysis further revealed a positive correlation between monorhinal and birhinal orthonasal olfaction with ipsilateral and overall OC-air volume. Likewise, birhinal and monorhinal orthonasal, and retronasal olfactory test results correlated negatively with the overall and ipsilateral Lund-Mackay scores. Monorhinal and birhinal orthonasal, and retronasal olfactory function were lower in CRS patients with higher ipsilateral and overall OC-opacification compared to those with lower OC-opacification.