Does endoscopic sinus surgery improve olfaction in nasal polyposis?

Olfactory dysfunction in chronic rhinosinusitis: insights into the underlying mechanisms and treatments

INTRODUCTION

Olfactory dysfunction (OD) is a typical symptom of chronic rhinosinusitis (CRS), which adversely affects the patient's quality of life and results in mood depression. Studies investigating the impairment of olfactory epithelium (OE) have indicated that inflammation-induced cell damage and dysfunction in OE plays a vital role in the development of OD. Consequently, glucocorticoids and biologics are beneficial in the management of OD in CRS patients. However, the mechanisms underlying OE impairment in CRS patients have not been fully elucidated.

AREAS COVERED

This review focuses on mechanisms underlying inflammation-induced cell impairment in OE of CRS patients. Additionally, the methods used for detection of olfaction and both currently available and potentially new clinical treatments for OD are reviewed.

EXPERT OPINION

Chronic inflammation in OE impairs not only olfactory sensory neurons but also non-neuronal cells that are responsible for regeneration and support for neurons. The current treatment for OD in CRS is mainly aimed at attenuating and preventing inflammation. Strategies for use of combinations of these therapies may achieve greater efficacy in restoration of the damaged OE and consequently better management of OD.

Olfaction in nasal polyp patients after Reboot surgery: an endotype-based prospective study

PURPOSE

To report biomarkers present in the olfactory mucosa in chronic rhinosinusitis with nasal polyps (CRSwNP) in comparison with nasal polyps and to nasal mucosal tissues from control patients. To evaluate the kinetics of smell over 6 months in patients who underwent Reboot surgery.

METHODS

Cohort study from May 2021 to May 2022. We collected samples of olfactory mucosa and nasal polyps from 16 CRSwNP patients and inferior turbinate samples from 20 control subjects. The study was not randomized for surgical and/or medical treatment. Samples were analyzed by Luminex and Unicap 100 to measure biomarkers of inflammation (IL1-β, IL4, IL5, IL6, IL17, CCL3, CCL4, G-CSF, SE-IgE, total IgE and ECP). 12 of the CRSwNP patients underwent Extended Sniffin'tests at timepoints 1-4 days pre-surgery, and 1, 3 and 6 months after Reboot surgery.

RESULTS

Type-2 markers were significantly elevated in OM and polyp tissue in CRSwNP (n = 16) vs. controls (n = 20), P < 0.05. TDI scores improved already 1 month (P < 0.05) after surgery and remained stable for 6 months. Type-2 inflammation in nasal polyps was associated with decreased sense of smell and taste before surgery, but improved after surgery (P = 0.048). Type-3 inflammation was present in the olfactory mucosa and was associated with a better sense of smell before surgery, but a smaller improvement of smell afterward.

CONCLUSIONS

Type-2 inflammation is present in the olfactory mucosa in CRSwNP patients and is associated with smell loss. Reboot surgery, aiming to completely remove inflamed sinus mucosa, significantly improves the smell in this group of patients.

Reboot surgery for chronic rhinosinusitis with nasal polyposis: recurrence and smell kinetics

OBJECTIVE

To evaluate the time for recovery of the sense of smell in patients with CRSwNP who underwent Reboot surgery compared to patients undergoing ESS in a long-term follow-up study.

METHODS

Data were collected retrospectively from 168 patients with severe uncontrolled CRSwNP, who underwent revision surgery, either as Extended Endoscopic Sinus Surgery (Reboot, 140 patients) or as regular Endoscopic Sinus Surgery (ESS, 28 patients) between January 1, 2014, and December 31, 2015, aiming to compare the outcome of surgeries after 2 years of follow-up. Sense of smell was scored as judged by the patient using scores 0 to 3 reflecting a percentage estimate of remaining smell.

RESULTS

Smell improved similarly in the Reboot and ESS groups over the first 9 months, which was maintained over 24 months in the Reboot, but not the ESS group (p = 0.007 after 18 months, p = 0.001 after 24 months). Furthermore, polyp recurrence rates were significantly lower in the Reboot group.

CONCLUSION

Reboot surgery significantly improved olfactory function and significantly reduced nasal polyp recurrence rates over 2 years post-operatively. Therefore, Reboot should be considered for patients with uncontrolled severe CRSwNP, specifically when ESS failed, to offer long-term smell and a polyp-free status.

LEVEL OF EVIDENCE

3b.

Improvement of Subjective Olfactory Dysfunction in Chronic Rhinosinusitis With Nasal Polyps After Endoscopic Sinus Surgery

Objective

Olfactory impairment is a common complaint in patients with chronic rhinosinusitis with nasal polyps (CRSwNP), but the influence of endoscopic sinus surgery (ESS) on olfaction and the factors predicting olfactory impairment are not fully understood. This study aimed to assess the effect of ESS on improving olfactory dysfunction in patients with CRSwNP and to identify factors that predict prognosis.

Methods

A total of 56 patients with CRSwNP reported their self-evaluated olfactory dysfunction score preoperatively and 1 month, 3 months, and 12 months after ESS. Preoperative clinical characteristics, computed tomography (CT) scan, and sinonasal endoscopy examination results were collected before surgery. Additionally, factors that predicted olfactory loss and affected the improvement of olfaction after ESS were evaluated.

Results

Olfactory improvement can be observed 1 month after ESS. A total of 73.2% (41/56) subjects experienced sustained recovery of subjective olfaction with the self-evaluated olfactory dysfunction score improving from 2.04 to 0.64 (P < 0.001) after 12 months. The Lund–Mackay scores (r = 0.593, P < 0.001) and Lund–Kennedy scores (r = 0.265, P < 0.05) correlated with the preoperative olfactory dysfunction score. Multivariate logistic regression analysis revealed that longer duration of olfactory dysfunction, blood eosinophilia, lower Lund–Mackay scores, and peripheral distribution of CT opacification were risk factors that adversely affected the recovery of olfactory function (P < 0.05).

Conclusion

ESS improved self-evaluated olfactory function in patients with CRSwNP. Lund–Mackay scores and Lund–Kennedy scores were correlated with olfactory function prior to surgery, while a longer course of the disease, higher blood eosinophilia, lower Lund–Mackay scores, and peripheral distribution of CT opacification were risk factors for poor olfactory prognosis.

Significance of Medial Osteotomy on the Olfactory Function in Patients Who Underwent Septorhinoplasty

OBJECTIVE

This study was designed to explore the impact of medial osteotomy on olfactory function.

METHODS

This nonrandomized, prospective study included 60 adult patients who underwent open technique septoplasty (group 1), rhinoplasty with only lateral osteotomy (group 2), and septorhinoplasty with medial and lateral osteotomies (group 3). Olfactory functions were evaluated by using the Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory test. The CCCRC test includes the butanol threshold test and smell identification test using common smells. The butanol threshold test and smell identification test scores of each group were recorded preoperatively and at 1st and 4th months and compared.

RESULTS

Each group is consisted of 20 patients. The preoperative smell identification test and butanol threshold test scores were similar in each group. The smell identification test, butanol threshold test, and CCCRC olfactory test scores of the 1st month were statistically significantly low in group 3. There was no statistically significant difference between the groups at 4th month postoperatively.

CONCLUSION

The present study is the first analysis of the effect of medial osteotomy on olfactory function. Medial osteotomy may decrease the olfactory function in early time, but afterwards olfaction could recover at preoperative levels.