Topical Therapy in Anosmia: Relevance of Steroid-Responsiveness:

Exhaled Nitric Oxide and Olfactory Dysfunction in Patients with Asthma: Association with Chronic Rhinosinusitis

Objectives: Olfactory dysfunction is a clinical sign that is important to detect with coexistent upper airway comorbidities in patients with asthma. This study aimed to investigate the etiology of olfactory dysfunction in patients with asthma and the relationship between fractional exhaled nitric oxide (FeNO) levels. Materials and Methods: This study included 47 asthma patients who were evaluated for olfactory dysfunction at Hiroshima University Hospital between 2012 and 2020. The etiologies of olfactory dysfunction were evaluated, and they were classified according to the FeNO levels of patients with asthma. Results: Olfactory dysfunction was observed in 30 patients with asthma, with chronic rhinosinusitis (77%) being the most prevalent etiology. Eosinophilic chronic rhinosinusitis (ECRS) was the most prevalent etiology of olfactory dysfunction in asthma patients with high FeNO levels (≥25 ppb), while non-eosinophilic chronic rhinosinusitis (NCRS) was the most prevalent etiology in asthma patients with low FeNO levels (<25 ppb). Additionally, the prevalence of ECRS was significantly higher in asthma patients with olfactory dysfunction and high FeNO levels (74%) than in those with either high FeNO levels or olfactory dysfunction and those with low FeNO levels and no olfactory dysfunction (12% and 9%, respectively). Conclusions: We found that ECRS was the predominant cause of olfactory dysfunction in patients with high FeNO levels, while NCRS was more common in those with low FeNO levels. The present study showed that both ECRS and NCRS are common etiologies of olfactory dysfunction in patients with asthma. Additionally, this study supports the link between upper and lower airway inflammation in patients with asthma complicated with olfactory dysfunction.

Olfactory Function and Olfactory Disorders

The sense of smell is important. This became especially clear to patients with infection-related olfactory loss during the SARS-CoV-2 pandemic. We react, for example, to the body odors of other humans. The sense of smell warns us of danger, and it allows us to perceive flavors when eating and drinking. In essence, this means quality of life. Therefore, anosmia must be taken seriously. Although olfactory receptor neurons are characterized by regenerative capacity, anosmia is relatively common with about 5 % of anosmic people in the general population. Olfactory disorders are classified according to their causes (e. g., infections of the upper respiratory tract, traumatic brain injury, chronic rhinosinusitis, age) with the resulting different therapeutic options and prognoses. Thorough history taking is therefore important. A wide variety of tools are available for diagnosis, ranging from short screening tests and detailed multidimensional test procedures to electrophysiological and imaging methods. Thus, quantitative olfactory disorders are easily assessable and traceable. For qualitative olfactory disorders such as parosmia, however, no objectifying diagnostic procedures are currently available. Therapeutic options for olfactory disorders are limited. Nevertheless, there are effective options consisting of olfactory training as well as various additive drug therapies. The consultation and the competent discussion with the patients are of major importance.

Topical Administration of Mometasone Is Not Helpful in Post-COVID-19 Olfactory Dysfunction

Persistent olfactory dysfunction is a major concern post-COVID-19, affecting up to 5% of all patients. Different therapeutic options, including mometasone nasal spray, have been recommended, only some of which have been validated for post-COVID-19 olfactory dysfunction. In this study we psychophysically assessed the effect of intranasally applied mometasone furoate on the recovery of olfaction. The spray was applied with a long applicator so that the olfactory cleft could be reached effectively. After olfactory dysfunction had been confirmed psychophysically using Sniffin’ Sticks, patients were randomly assigned to two different treatment arms: the study group (n = 40) underwent olfactory training and intranasal administration of mometasone furoate twice daily, whereas the control group (n = 46) performed olfactory training only. After a study duration of three months, psychophysical testing of olfaction was repeated using Sniffin’ Sticks. We found no benefit of an additional topical administration of mometasone furoate compared to olfactory training alone. These results psychophysically confirm two previous studies which were based on patients’ subjective self-ratings. Our findings are in contrast to current recommendations for the management of olfactory dysfunction post-COVID-19, which might have to be adapted accordingly.

Management of Post-Infectious Anosmia and Hyposmia: A Systematic Review

BACKGROUND

Anosmia and hyposmia significantly affect patients' quality of life and have many etiologies, including trauma, inflammatory conditions including chronic rhinosinusitis, neoplasm, and viral infections, such as rhinovirus and SARS-CoV-2.

OBJECTIVE

Our purpose was to establish whether a consensus exists regarding optimal management of olfactory dysfunction and to provide insight into the treatment of anosmia in the current climate of increased prevalence secondary to COVID-19. Thus, we aimed to systematically review the literature on the management of non-Chronic-rhinosinusitis- related anosmia/hyposmia.

METHODS

PubMed, EMBASE, and Cochrane databases were searched for articles published since January 1990 using terms combined with Medical Subject Headings (MeSH). We included articles evaluating management of anosmia and hyposmia written in the English language, with original data, a minimum of 3 months of follow-up except for COVID-related studies, at least 2 patients, and well-defined and measurable outcomes.

RESULTS

A total of 3013 unique titles were returned upon the initial search. Of these, 297 abstracts were examined, yielding 19 full texts meeting inclusion criteria (8 with level 1 evidence, 3 with level 2, 1 with level 3, and 7 with level 4). The studies included a total of 1522 subjects, with follow up ranging from 3 to 72 months, with an exception for COVID related studies. Endpoints were based on clinically significant improvements of olfactory functions as measured through validated smell tests. Treatments with the most robust data were intranasal corticosteroids and olfactory training.

CONCLUSION

The literature on the treatment of anosmia and hyposmia includes randomized trials showing the efficacy of a few modalities. While further research is needed to expand therapeutic options for this debilitating condition, the current literature supports the use of olfactory training and topical corticosteroids.

Anosmia in COVID-19 Patients at a Health Center in Yogyakarta, Indonesia

BACKGROUND: SARS-CoV-2, which causes COVID-19, is one of the viruses that has been spreading globally since 2019. AIM: This research aims to see how common anosmia is among COVID-19 patients. MATERIALS AND METHODS: A retrospective study with a consecutive sample and quantitative descriptive design was utilized to collect data by spreading questionnaires on patient experiences COVID-19 infection. COVID-19 was detected by RT-PCR at a Health Center in Yogyakarta, Indonesia. RESULT: A total of 124 persons tested positive for COVID-19. The remaining 59% experienced no anosmia or smell issues. Anosmia was present in 40.3% of those examined, 57.3% of those tested had no anosmia before or after the RT-PCR test and 31.5 had it before being diagnosed with COVID-19. Less than 5 days, 13.7% of those who had recovered, whereas 22.6% had more than 5 days to recover. CONCLUSION: People who were diagnosed as COVID-19 positive using the RT-PCR test had the symptom earlier than those who reported anosmia after diagnosis, according to when they first reported it.

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.

“Anosmia” the mysterious collateral damage of COVID-19

COVID-19 pandemic spreads worldwide, with more than 100 million positive cases and more than 2 million deaths. From the beginning of the COVID-19 pandemic, several otolaryngologists described many cases of a sudden loss of smell (anosmia) associated with the disease with or without additional symptoms. Anosmia is often the first and sometimes the only sign in the asymptomatic carriers of COVID-19. Still, this disorder is underestimated, and it is not life-threatening. However, it significantly decreases the quality of life. This olfactory dysfunction continues in several cases even after the nasopharyngeal swab was negative. The occurrence of anosmia can be used as a screening tool for COVID-19 patients and can be used to identify these patients to accomplish the isolation and tracking procedures. In this review, we highlighted the possible mechanisms of anosmia in COVID-19 patients, major pathologies and features of anosmia, implications of anosmia in early diagnosis of COVID-19, evaluation of the smell function during COVID-19, and management and treatment options of COVID-19 anosmia.

Olfactory dysfunction as a post-infectious symptom of SARS-CoV-2 infection

The unexpected onset smell and taste disability was being recognized as a COVID-19 related symptom. Loss of smell might occur alone or be followed by other COVID-19 symptoms, such as a dry cough, fever, headache, and shortness of breath. Other virus infections have been linked to anosmia (parainfluenza, rhinovirus, SARS, and others), affecting up to 20% of the adult population, which is much less common than SARS-CoV-2 infection. A hypothesis about the pathophysiology of post-infectious olfactory loss is that viruses could make an inflammatory response of the nasal mucosa or directly damage the olfactory neuroepithelium. However, in patients with COVID-19, loss of smell may occur without other rhino logic symptoms or suggestive nasal inflammation. According to evidence, anosmia-related SARS-CoV-2 could be a new viral syndrome unique to COVID-19. Furthermore, through experimental intranasal inoculation in mice, SARS-CoV-2 can be inoculated into the olfactory neural circuitry. This disease has not had the required focus, most likely because it is not life-threatening in and of itself. Though patients' quality of living is significantly reduced as their olfactory ability is lost, resulting in lowering and inadequate appetite, excessive or unbalanced food consumption, as well as an overall sense of insecurity. This review aims to give a quick overview of the latest epidemiological research, pathological mechanisms for the dysfunction of smell, and taste in patients infected with SARS-CoV-2. In addition, the initial diagnosis and treatment options for dysfunction are also discussed.

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The pathological mechanism of SARS-CoV-2 infection in olfactory dysfunction.

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Pathognomonic symptoms of sinonasal impairment in COVID-19 patients.

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Treatment of olfactory dysfunction after SARS-CoV-2 infection.

The potential therapeutic effect of platelet-rich plasma in the treatment of post-COVID-19 parosmia

Background

COVID-19-related olfactory dysfunction is an emerging problem with a significant impact on the quality of life of affected individuals. Different lines of treatment have been used with varying results. This study aimed to assess the potential therapeutic effect of PRP in the treatment of post-COVID olfactory dysfunction. This work aimed to assess the potential therapeutic effect of platelet-rich plasma (PRP) in treating post-COVID-19 parosmia. A pilot study was conducted on 60 patients with post-COVID parosmia without responding to a 3-month course of olfactory training, topical corticosteroids, omega-three, vitamin B12, and zinc supplementation. The patients were distributed randomly and equally among 2 groups. The case group was subjected to three PRP injections in the olfactory cleft at 3 weeks intervals. The control group continued the pre-study treatment protocol for 6 weeks. The degree of parosmia was assessed before and after treatment subjectively using a visual analog scale (VAS) from 0 to 10. Reaching 0–1 on the visual analog scale was a complete improvement. The primary outcome was assessing the post-treatment score for parosmia 1 month after the third injection in the case group. The second outcome was the comparison between both groups regarding the degree of improvement 1 month after cessation of treatment.

Results

There was a highly significant improvement in VAS for parosmia (p < 0.00001) in the case group and a significant improvement in VAS for parosmia in the control group (p = P = 0.00148). There was a significant difference between both groups regarding the degree of improvement favoring the case group (p = 0.002).

Conclusion

Platelet-rich plasma injection in the olfactory cleft offers a therapeutic option for treating patients with post-COVID-19 olfactory parosmia who failed to respond to traditional conservative treatment.

Steroids and Olfactory Training for Postviral Olfactory Dysfunction: A Systematic Review

Background: Postviral olfactory dysfunction (PVOD) is a clinical challenge due to limited therapeutic options and poor prognosis. Both steroids and olfactory training have been proved to be effective for olfactory dysfunction with varied etiologies. We sought to perform a systematic review to summarize the evidence of steroids or olfactory training for patients with PVOD.

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 PVOD receiving steroid or olfactory training.

Results: Of the initial 273 abstracts reviewed, 20 articles with data from 2,415 patients with PVOD were included. Treatments including topical steroids, systemic steroids, classical olfactory training (COT), modified olfactory training (MOT), and olfactory training with steroid were analyzed. Both psychophysical olfactory testing and subjective symptom scores were utilized to assess the olfactory function. The routine use of nasal steroid spray alone during the management of PVOD seems to have no positive effect on olfactory dysfunction. Direct injection of steroid or nasal steroid spray into the olfactory cleft significantly improved the olfactory function in patients with PVOD. Olfactory improvement is greater than that of the natural course of the disease with short-term COT. Patients with PVOD would benefit more from long-term COT (>12 weeks). Treatment duration, various odorants, olfactory training devices, changing the types of odors periodically, different molecular odorants, and different concentrations of odorants tended to increase the efficiency of MOT. Clinically significant improvement after olfactory training was defined as an increase of threshold, discrimination, and identification (TDI) score ≥6. From week 24 to week 36, both COT and MOT groups reached the maximum therapeutic effect regarding the number of participants achieving clinically significant improvement. A combination of local or oral steroids with olfactory training is more efficient than COT only.

Conclusion: Olfactory function in patients with PVOD was effectively improved through direct steroid administration in the olfactory cleft, COT, or modification of COT. The addition of topical steroids to COT therapy showed a tendency for greater olfactory improvement in patients with PVOD.

Postinfectious Olfactory Dysfunction: Oral Steroids and Olfactory Training versus Olfactory Training Alone: Is There any Benefit from Steroids?

INTRODUCTION

There are limited treatment options for postinfectious olfactory dysfunction (PIOD). Olfactory training has recently been used in clinical practice, but no medical treatment is widely accepted. Although there is weak evidence for their value, some physicians use oral corticosteroids as first-line treatment. The aim of this study was to compare combined oral methylprednisolone and olfactory training with olfactory training alone in the management of PIOD.

METHODS

This prospective cohort study included 131 patients with PIOD over a 2-year period before the COVID-19 pandemic. Seventy-eight patients who were treated with oral methylprednisolone and olfactory training (group A) were compared with 53 patients who were treated with olfactory training only (group B). Olfactory function was evaluated with "Sniffin' Sticks" at baseline and 2, 8, and 16 weeks after initial assessment. Patients who improved after steroid treatment underwent magnetic resonance imaging of the paranasal sinuses, skin prick tests, lung spirometry, and sputum eosinophil assessment.

RESULTS

Oral steroids improved 19.23% of patients (n = 15) of group A. History, clinical evaluation, imaging, and laboratory tests identified an inflammatory background in half of them (n = 8). The remaining 7 had no findings of nasal inflammation, and all had a short history of olfactory dysfunction. Both groups significantly improved in olfactory testing results at the end of the olfactory training scheme without significant difference between them.

CONCLUSIONS

The percentage of improved patients after oral methylprednisolone was relatively low to suggest it as first-line treatment. Half of the improved patients had an underlying upper airway inflammatory condition not related to the infection that caused the acute loss of olfactory function.

Adverse Events Associated with Intranasal Sprays: An Analysis of the Food and Drug Administration Database and Literature Review

BACKGROUND

Intranasal sprays (INSs) are commonly used medications for the treatment of many rhinologic conditions. Despite their popularity, an analysis of a nationwide reporting database and comparison to the available literature has never been performed.

METHODS

The Food and Drug Administration Adverse Event Reporting System (FAERS) database was accessed to obtain adverse event (AE) records from 2014 to 2019 for varying INSs, including: 10 corticosteroids, 1 alpha adrenergic, and 3 antihistamines. The Proportional Reporting Ratios (PRR) and Reporting Odds Ratios (ROR) were calculated for dyspnea, anosmia, ageusia/dysgeusia, epistaxis, and headache. A PRR ≥ 2 or ROR ≥ 1 was considered significant.

RESULTS

Corticosteroids had 98 864 total reported AEs to the database, followed by antihistamines (7011) and alpha adrenergics (2071). In total, dyspnea was reported 5843 times, followed by headache (4230), epistaxis (1205), ageusia/dysgeusia (920), and anosmia (312). Overall, PRR and ROR values for dyspnea ranged from 0.51 to 4.25 and 0.51 to 4.49; for dysgeusia/ageusia from 0.56 to 6.09 and 0.56 to 6.12; and for epistaxis from 1.03 to 27.24 and 1.03 to 30.76, respectively. All medications which listed anosmia within the top AEs had PRR and ROR values exceeding 2 and 1, respectively. The PRR for headache exceeded 2 for 1 medication and the ROR exceeded 1 in 7 medications.

CONCLUSION

The AEs of dyspnea, anosmia, ageusia/dysgeusia, epistaxis, and headache are reported within the FAERS database for commonly prescribed INSs. When compared against the existing scientific literature, the clinical significance of this reporting tool from the FDA for these classes of medications remains unvalidated.

Prevalence of Olfactory Dysfunction in Coronavirus Disease 2019 (COVID-19): A Meta-analysis of 27,492 Patients

OBJECTIVES/HYPOTHESIS

Olfactory dysfunction has been observed as one of the clinical manifestations in COVID-19 patients. We aimed to conduct a systematic review and meta-analysis to estimate the overall pooled prevalence of olfactory dysfunction in COVID-19 patients.

STUDY DESIGN

Systematic review and meta-analyses.

METHODS

PubMed, Scopus, Web of Science, Embase, and Google Scholar databases were searched to identify studies published between 1 December 2019 and 23 July 2020. We used random-effects model to estimate the pooled prevalence with 95% confidence intervals (CIs). Heterogeneity was assessed using the I2 statistic and Cochran's Q test. Robustness of the pooled estimates was checked by different subgroup and sensitivity analyses This study is registered with PROSPERO (CRD42020183768).

RESULTS

We identified 1162 studies, of which 83 studies (n = 27492, 61.4% female) were included in the meta-analysis. Overall, the pooled prevalence of olfactory dysfunction in COVID-19 patients was 47.85% [95% CI: 41.20-54.50]. We observed olfactory dysfunction in 54.40% European, 51.11% North American, 31.39% Asian, and 10.71% Australian COVID-19 patients. Anosmia, hyposmia, and dysosmia were observed in 35.39%, 36.15%, and 2.53% of the patients, respectively. There were discrepancies in the results of studies with objective (higher prevalence) versus subjective (lower prevalence) evaluations. The discrepancy might be due to false-negative reporting observed in self-reported health measures.

CONCLUSIONS

The prevalence of olfactory dysfunction in COVID-19 patients was found to be 47.85% based on high-quality evidence. Due to the subjective measures of most studies pooled in the analysis, further studies with objective measures are advocated to confirm the finding.

LEVEL OF EVIDENCE

2 Laryngoscope, 131:865-878, 2021.

[Neuromuscular complications of SARS-CoV-2 infections-Part 1: peripheral nerves]

In recent months various disorders and diseases of the peripheral nerves (including cranial nerves) and the musculature have been described in association with the pulmonary disease coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In the first part of our review the current knowledge about a potential association of a SARS-CoV‑2 infection with dysfunction and diseases of cranial and peripheral nerves is discussed. Anosmia, ageusia, motor cranial nerve involvement and Guillain-Barré syndrome (GBS) were described in a temporal association with a SARS-CoV‑2 infection. Several studies could show that anosmia and ageusia were frequent symptoms of a SARS-CoV‑2 infection. In contrast the failure of other cranial nerves has so far only been sporadically described. A number of case reports and case series indicate a causal association between a SARS-CoV‑2 infection and GBS but epidemiological evidence is still lacking.

Clinical Olfactory Working Group consensus statement on the treatment of postinfectious olfactory dysfunction

BACKGROUND

Respiratory tract viruses are the second most common cause of olfactory dysfunction. As we learn more about the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with the recognition that olfactory dysfunction is a key symptom of this disease process, there is a greater need than ever for evidence-based management of postinfectious olfactory dysfunction (PIOD).

OBJECTIVE

Our aim was to provide an evidence-based practical guide to the management of PIOD (including post-coronavirus 2019 cases) for both primary care practitioners and hospital specialists.

METHODS

A systematic review of the treatment options available for the management of PIOD was performed. The written systematic review was then circulated among the members of the Clinical Olfactory Working Group for their perusal before roundtable expert discussion of the treatment options. The group also undertook a survey to determine their current clinical practice with regard to treatment of PIOD.

RESULTS

The search resulted in 467 citations, of which 107 articles were fully reviewed and analyzed for eligibility; 40 citations fulfilled the inclusion criteria, 11 of which were randomized controlled trials. In total, 15 of the articles specifically looked at PIOD whereas the other 25 included other etiologies for olfactory dysfunction.

CONCLUSIONS

The Clinical Olfactory Working Group members made an overwhelming recommendation for olfactory training; none recommended monocycline antibiotics. The diagnostic role of oral steroids was discussed; some group members were in favor of vitamin A drops. Further research is needed to confirm the place of other therapeutic options.

Acute Olfactory Dysfunction-A Primary Presentation of COVID-19 Infection

COVID-19 is a zoonotic illness caused by a new strain of coronavirus and has recently been declared a pandemic by the World Health Organization, with an estimated fatality rate of 1% to 2%. Early identification and isolation of patients in the preliminary infective stage has been a mainstay of most governmental strategies in order to limit transmission. Four otherwise healthy patients presented to a specialist open access Ear, Nose & Throat Clinic in central London with acute total or subtotal loss of their sense of smell in a single one-week period, coinciding with rapid escalation of COVID-19 infection in the indigenous population. The diagnosis was confirmed by the validated University of Pennsylvania Smell Identification Test (UPSIT) in 3. Endoscopic examination and magnetic resonance imaging (2 cases) excluded a range of alternative potential pathological conditions. Covid-19 antibody testing carried out 6 to 8 weeks after the onset of nasal symptoms showed positive immunoglobulin G antibodies in 3 of the 4 patients. Acute severe anosmia is therefore almost certainly an unusual presenting local nasal feature of a COVID-19 viral infection. All 4 patients achieved significant partial olfactory recovery by one week after treatment with subjective ratings of 40% to 85% of normal (mean 60%) and complete olfaction recovery after 2 to 3 weeks in all 4 patients. The significance, possible pathogenesis, and public health implications are highlighted and discussed.

Pharmacologic therapy of olfaction disroders induced by COVID-19 upper respiratory infection

Postviral olfactory disorder refers to the sensorineural olfactory loss caused by upper respiratory tract infections. With the increasing awareness of olfactory or gustatory dysfunction as a potential early symptom of coronavirus disease 2019, postviral olfactory disorder has been attracting much attention. Postviral olfactory disorder is the most common type of olfactory disorder, especially among women aged over 50 years. Systemic or topical corticosteroids have commonly been used for treating this disorder, but the mechanism of corticosteroid action is unclear. Other medical treatment options such as alpha-lipoic acids and caroverine that stimulate nerve growth factor expression or prevent glutamatergic neurotoxicity have also been used. Although these drugs have been found to be useful in the treatment of postviral olfactory disorder in previous studies, the efficacy has not been statistically proven through a meta-analysis. Recently, olfactory training has been introduced in the treatment strategy for postviral olfactory disorder. It is a safe option without side effects that can be used for treating olfactory disorders caused by upper respiratory tract infections. Further rigorous studies are needed to determine the efficacy of the combination of drug treatment and olfactory training.

Anosmia and ageusia associated with coronavirus infection (COVID-19) - what is known?

In 2020 a new pandemic caused by the SARS-CoV-2 coronavirus is affecting the lives of millions of patients and healthcare workers worldwide. The clinical picture of this infection is in a dynamic process of discovery, and more symptoms emerge as the clinicians observe and diagnose manifestations that affect multiple organs. Anosmia (loss of smell), and ageusia (loss of taste) become more frequently cited as independent symptoms or in association with the most common manifestations of the disease, such as fever, cough and dyspnea. A thorough screening program will prevent most nosocomial and community-acquired infections by promoting efficient triage and specific measures such as isolation of the patients. Therefore, it is important to include frequent symptoms in the anamnesis and questionnaires to select those patients who might benefit from testing, isolation, and treatment. This study summarizes the existing data regarding the association of anosmia and ageusia with the SARS-CoV-2 infection. It also aims to describe manifestations of these, particularly in the clinical picture of all symptomatic patients.

The diagnostic value of detecting sudden smell loss among asymptomatic COVID-19 patients in early stage: The possible early sign of COVID-19

IMPORTANCE

The newly emerged coronavirus disease 19 (COVID-19), is threatening the world. Olfactory or gustatory dysfunction is reported as one of the symptoms worldwide. As reported so far, different clinical features have been reported according to outbreak sites and gender; most of the patients, who complained of anosmia or hyposmia, were Europeans. We had a fast review for novel articles about COVID-19 infection and olfactory function.

OBSERVATIONS

Rapid reviews for COVID-19 or other viral infection and olfactory and/or gustatory dysfunctions were done in this review. Up to date, a lot of reports have shown that olfactory dysfunction is related to viral infections but no exact mechanism, clinical course, and definite treatment have been discovered, which is also same in COVID-19. In general, intranasal steroid (INS) and oral steroid for short time help improve the recovery of the olfactory function in case of olfactory dysfunction after virus infection. Considering severe respiratory complications and immunocompromised state of COVID-19, the use of steroid should be limited and cautious because we do not have enough data to support the usage of steroid to treat olfactory dysfunction in the clinical course of COVID-19.

CONCLUSIONS AND RELEVANCE

In the days of pandemic COVID-19, we should keep in mind that olfactory dysfunctions, even without other upper respiratory infection or otolaryngologic symptoms, might be the early signs of COVID-19.

Treatment of post-viral olfactory dysfunction: an evidence-based review with recommendations

Background

Post‐viral olfactory dysfunction (PVOD) is one of the most common causes of olfactory loss. Despite its prevalence, optimal treatment strategies remain unclear. This article provides a comprehensive review of PVOD treatment options and provides evidence‐based recommendations for their use.

Methods

A systematic review of the Medline, Embase, Cochrane, Web of Science, Scopus, and Google Scholar databases was completed according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. Studies with defined olfactory outcomes of patients treated for PVOD following medical, surgical, acupuncture, or olfactory training interventions were included. The Clinical Practice Guideline Development Manual and Conference on Guideline Standardization (COGS) instrument recommendations were followed in accordance with a previously described, rigorous, iterative process to create an evidence‐based review with recommendations.

Results

From 552 initial candidate articles, 36 studies with data for 2183 patients with PVOD were ultimately included. The most common method to assess olfactory outcomes was Sniffin’ Sticks. Broad treatment categories included: olfactory training, systemic steroids, topical therapies, a variety of heterogeneous non‐steroidal oral medications, and acupuncture.

Conclusion

Based on the available evidence, olfactory training is a recommendation for the treatment of PVOD. The use of short‐term systemic and/or topical steroids is an option in select patients after careful consideration of potential risks of oral steroids. Though some pharmacological investigations offer promising preliminary results for systemic and topical medications alike, a paucity of high‐quality studies limits the ability to make meaningful evidence‐based recommendations for the use of these therapies for the treatment of PVOD.

Differences in Mechanisms of Steroid Therapy and Olfactory Training for Olfactory Loss in Mice

Objective

Steroid therapy and olfactory training are common treatments for olfactory loss. Systemic steroid treatment is the most effective approach for treating sinonasal olfactory loss. Olfactory training is typically effective for treating sensorineural olfactory loss. However, the differences in mechanisms of steroid therapy and olfactory training for olfactory dysfunction are unclear. The aim of this study was thus to evaluate the differences in mechanisms of olfactory training and steroid therapy.

Subjects and Methods

Mice in each group were administered 3-methylindole at a dose of 300 mg/kg. Olfactory function was evaluated with a food-finding test once a week. The olfactory neuroepithelium was harvested for histologic examination and protein analysis. Subsequently, data analysis, gene ontology and pathway analysis, quantitative real-time polymerase chain reaction of mRNA, and western blot analysis were conducted.

Results

Mice were divided into four groups according to treatment. Control, anosmia, training, and steroid groups resumed food-finding. MMP27, CCL22 and IL18rap mRNA expression were significantly increased in the training group compared to that in the steroid group. IL1R2 mRNA expression was significantly higher in the olfactory neuroepithelium of steroid-treated mice than in that of the training group mice.

Conclusions

Steroid therapy improved olfactory function via anti-inflammatory effects, unlike olfactory training which involved cell regeneration and tissue remodeling. Protein and gene analyses revealed that steroid therapy and olfactory training are underpinned by distinct mechanisms. Selection of the most appropriate treatment will be dependent on the cause of olfactory loss.

Correlation of mucus inflammatory proteins and olfaction in chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) is one of the most common causes of olfactory loss, but the pathophysiology underlying olfactory dysfunction in CRS has not been fully elucidated. Previous studies found correlations between olfactory cleft (OC) inflammatory cytokines/chemokines and olfaction in CRS. The purpose of this study was to evaluate the relationship between OC mucus inflammatory proteins and olfaction in a multi-institutional cohort.

METHODS

Adults with CRS were prospectively recruited. Demographics, comorbidities, olfactory assessment (Sniffin' Sticks), computed tomography (CT), and OC mucus for protein analysis were collected. Statistical analysis was performed to determine associations between olfactory function, OC mucus protein concentrations, and CT opacification.

RESULTS

Sixty-two patients were enrolled in the study, with an average age of 48.2 (standard deviation, 16.2) years, and 56.5% were female and 59.7% were classified as CRS with nasal polyps (CRSwNP). Ten of 26 OC mucus proteins were significantly correlated with threshold, discrimination, and identification (TDI) scores and OC opacification. Subgroup analysis by polyp status revealed that, within the CRSwNP group, C-C motif ligand 2 (CCL2), interleukin-5 (IL-5), IL-6, IL-13, IL-10, IL-9, tumor necrosis factor-α (TNF-α), CCL5, and CCL11 were significantly correlated with olfaction. For CRS without nasal polyps (CRSsNP), only C-X-C ligand 5 (CXCL5) showed a correlation. In CRSwNP, IL-6, IL-10, vascular endothelial growth factor-A, and immunoglobulin E (IgE) correlated with OC opacification, whereas, in CRSsNP, only CXCL5 showed a correlation. OC mucus proteins and Lund-Mackay score correlated only in the CRSsNP group (CXCL5, IL-5, IL-13, IgE).

CONCLUSION

Several OC mucus proteins have been found to correlate with olfactory function and OC opacification. The profile of OC mucus proteins differs between CRSsNP and CRSwNP subgroups, suggesting different mechanisms between groups, but further study is required.

Olfactory cleft mucus proteins associated with olfactory dysfunction in a cohort without chronic rhinosinusitis

BACKGROUND

Olfactory dysfunction (OD) is a common problem, affecting up to 20% of the general population. Previous studies identified olfactory cleft mucus proteins associated with OD in chronic rhinosinusitis (CRS) but not in a healthy population. In this study we aimed to identify olfactory cleft mucus proteins associated with olfaction in individuals without sinus disease.

METHODS

Subjects free of sinus disease completed medical history questionnaires that collected data regarding demographics, comorbidities, and past exposures. Olfactory testing was performed using Sniffin' Sticks, evaluating threshold, discrimination, and identification. Olfactory cleft mucus (OC) and, in select cases, inferior turbinate mucus (IT) were collected with Leukosorb paper and assays performed for 17 proteins, including growth factors, cytokines/chemokines, cell-cycle regulators, and odorant-binding protein (OBP).

RESULTS

Fifty-six subjects were enrolled in the study, with an average age of 47.8 (standard deviation [SD], 17.6) years, including 33 females (58.9%). The average threshold/discrimination/identification (TDI) score was 30.3 (SD, 6.4). In localization studies, OBP concentrations were significantly higher in OC than IT mucus (p = 0.006). Cyclin-dependent kinase inhibitor 2A (CDKN2A/p16INK4a), basic fibroblast growth factor (bFGF), chemokine ligand 2 (CCL2/MCP-1), granulocyte macrophage colony-stimulating factor (GM-CSF), and chemokine ligand 20 (CCL20/MIP-3a) all inversely correlated with overall TDI (all rho ≥ -0.479, p ≤ 0.004). Stem cell factor (SCF) correlated positively with overall TDI (rho = 0.510, p = 0.002).

CONCLUSION

Placement of Leukosorb paper is relatively site-specific for olfactory proteins and it is feasible to collect a variety of olfactory cleft proteins that correlate with olfactory function. Further study is required to determine mechanisms of OD in non-CRS subjects.

Intranasal application of glucocorticoid alleviates olfactory dysfunction in mice with allergic rhinitis

The aim of the present study was to investigate the effect of glucocorticoid intervention on olfactory dysfunction in mice with allergic rhinitis (AR). An AR animal model was established by intraperitoneal injection and intranasal application of ovalbumin to mice. The olfactory function of the mice was evaluated using a buried food test, and morphological changes in the nasal mucosa were determined using hematoxylin and eosin staining. The expression of olfactory marker protein (OMP) in the olfactory mucosa was tested by immunohistochemistry, and was observed on days 7 and 14 after the application of glucocorticoid. The incidence rate of olfactory dysfunction in AR mice was 75.34%, and the olfactory epithelium became thinner in mice with AR compared to the control group. In addition, the expression of OMP in the olfactory epithelium was downregulated in mice with AR compared with the control group. Expression of OMP in the olfactory epithelium was upregulated in the budesonide group A and betamethasone group A compared with the medicine-free group, whereas the expression of OMP in the olfactory epithelium of budesonide group A or betamethasone group A was not significantly different from the control group. Moreover, the expression of OMP in the budesonide group B was similar to budesonide group A, and expression of OMP in betamethasone group B was similar to betamethasone group A. The expression of OMP in olfactory mucosa is downregulated in AR mice with olfactory dysfunction. Following the application of glucocorticoid, the expression of OMP in the olfactory mucosa in mice is upregulated. Moreover, intranasal local glucocorticoid has a low incidence of systemic adverse reactions, and is recommended for the treatment of olfactory dysfunction in AR.

Anosmia: Differential diagnosis, evaluation, and management

The ability to scrutinize our surroundings remains heavily dependent on the sense of smell. From the ability to detect dangerous situations such as fires to the recollection of a fond memory triggered by an odor, the advantages of an intact olfactory system cannot be overstated. Outcomes studies have highlighted the profound negative impact of anosmia and parosmia on the overall quality of life. The National Institute on Deafness and Other Communication Disorders estimates that ∼1.4% of the United States population experiences chronic olfactory dysfunction and smell loss. Efforts have focused on improving both the diagnosis of olfactory dysfunction through olfactory testing and improved reporting of treatment outcomes of olfactory training. The purpose of this article was to review the differential diagnosis, workup, and current treatment strategies of anosmia and smell disorders.

Prognosis of Olfactory Dysfunction according to Etiology and Timing of Treatment

Objective We evaluated the severity of olfactory impairment according to risk factors, compared responses with risk factors and treatment timing, and investigated prognosis according to treatments. Study design Case series with chart review. Setting Tertiary referral center. Subjects and Methods We retrospectively reviewed medical records of patients complaining of loss of their sense of smell between January 2006 and May 2016. In total, 491 patients were included. We evaluated olfactory function using the Connecticut Chemosensory Clinical Research Center test (threshold test) and Cross-cultural Smell Identification Test. Results Post-upper respiratory infection patients showed better results than those with other risk factors (59.6% recovered). Patients with head trauma (12.5% recovered) and congenital olfactory dysfunction (0% recovered) showed poorer results. Earlier treatment showed better olfactory recovery outcomes for post-upper respiratory infection ( P = .001), head trauma ( P = .022), and nasal/sinus surgery ( P = .009). Xerostomia ( P = .73) and idiopathy ( P = .365) showed no significant difference in terms of treatment timing. The threshold test better reflected subjective recovery than the identification test. The systemic + topical steroid group and the systemic steroid treatment group both showed better smell recovery outcomes than the group with topical treatment alone (both, P < .001). However, there was no significant difference between the systemic treatment group and the systemic + topical treatment group ( P = .978). Conclusions Our findings suggest that the duration of smell loss is important for better olfactory outcomes with most etiologies. Also, the effects of systemic steroids were better than those of topical steroids, regardless of combined treatment.

Twice-daily application of topical corticosteroids with a squirt system for patients with steroid-responsive olfactory impairment

CONCLUSION

Twice-daily topical corticosteroid treatment using a squirt system was beneficial in maintaining improvements in olfactory dysfunction which had been achieved by oral steroid treatment.

OBJECTIVES

Some patients suffering from olfactory dysfunction respond well to corticosteroids. However, maintaining these improvements is challenging. The aim of this study was to evaluate the maintenance effect of twice-daily topical steroid treatment using a squirt system.

METHODS

Twenty-two anosmic patients with an increase in odor threshold, discrimination, and identification (TDI) scores in Sniffin' Sticks tests by more than six points after 1-week of oral steroid treatment were enrolled. All the patients used a squirt system to apply topical corticosteroids and were followed up at 1, 3, and 6 months.

RESULTS

Nineteen, 16, and 10 patients were followed-up at 1, 3, and 6 months after treatment, respectively. All the patients had significant visual analog scale scores improvements compared to pre-treatment. The mean improvements in TDI scores were 9.80 (p < 0.001), 11.58 (p = 0.001), and 13.87 (p = 0.005) after 1, 3, and 6 months of treatment, respectively. The self-rated and objective olfactory function scores were maintained with steroid squirt therapy without significant decline, even in the patients who were followed up for 6 months.

Recovery of Olfactory Function in Postviral Olfactory Dysfunction Patients after Acupuncture Treatment

Introduction. The aims of this study were to assess the impact of traditional Chinese acupuncture (TCA) in postviral olfactory dysfunction (PVOD) patients who were refractory to standardized treatment and to compare the results with the impact observed in an observation group. Methods. Fifty patients who presented to the outpatient clinic with PVOD and were refractory to standardized treatment were included: 25 were treated with TCA and 25 patients were simply observed. A subjective olfactory test was performed using the University of Pennsylvania Smell Identification Test (UPSIT). The effects of TCA were compared with the results obtained in the observation group. Results. Improved olfactory function was observed in eleven patients treated with TCA compared with four patients in the observation group. This study revealed significantly improved olfactory function outcomes in patients who underwent acupuncture compared with the observation group. No significant differences in olfaction recovery were found according to age, gender, or duration of disease between the two groups; however, hyposmic patients recovered at a higher rate than anosmic patients. Conclusion. TCA may aid the treatment of PVOD patients who are refractory to drugs or other therapies.

Prognosis of postviral olfactory loss: follow-up study for longer than one year

BACKGROUND

There have been very few studies on the prognosis of postviral olfactory dysfunction. The aim of the study was to evaluate its long-term prognosis and factors influencing the prognosis.

METHODS

This study included patients who were diagnosed with postviral olfactory dysfunction at least one year ago in a Smell and Taste Clinic and whose telephone interviews were available. Their medical records were reviewed, and they were asked to score their subjective olfactory function on a 100-point scale by telephone interview.

RESULTS

A total of 63 patients and 20 normal controls without nasal pathology were included. The mean age of the patients was 49.5 years, and 19 males and 44 females were included. The mean length of follow-up was 33.4 months. Olfactory dysfunction was subjectively improved in 85.7% of the patients. The recovery rate to subjective normosmia was 31.7%. The mean symptom scores for smell significantly increased in comparison with baseline from 25.6 to 69.0. Among the 25 patients (37.7%) who underwent follow-up butanol threshold test (BTT), the score improved from 4.6 to 7.3. Olfactory improvement was more frequently reported by females (p = .003) and in patients with follow-up duration for longer than 2 years (p = .043).

CONCLUSIONS

Follow-up of postviral olfactory loss revealed that over 80% of the patients reported subjective recovery after one year. The more favorable prognosis was associated with longer follow-up duration and female gender.

Topical corticosteroids applied with a squirt system are more effective than a nasal spray for steroid-dependent olfactory impairment

OBJECTIVES/HYPOTHESIS

Oral corticosteroids may restore conductive olfactory dysfunction that has been defined as steroid-dependent olfactory loss, but the effect may be temporary. This study was designed to evaluate whether applying topical corticosteroids with a squirt system was more effective than using a nasal spray to maintain olfactory improvement following oral corticosteroids.

STUDY DESIGN

Prospective randomized trial enrolling 32 patients.

METHODS

Patients were enrolled if they had suffered from olfactory dysfunction for more than 3 months, and if their composite scores of odor threshold, discrimination, and identification scores in Sniffin' Sticks olfactory tests increased by more than six points after 1 week of oral corticosteroid treatment. A total of 32 patients were enrolled and randomized into two groups. All patients were treated with topical corticosteroids for 2 months using either the spray or squirt system, respectively.

RESULTS

Both measured and self-rated olfactory functions after 1 and 2 months of topical corticosteroid treatment were better in the squirt group than in the spray group. However, 2 months of topical corticosteroid treatment with the squirt system only partially maintained olfactory improvement.

CONCLUSIONS

The application of topical corticosteroids with a squirt system was more effective than with a spray in maintaining olfactory improvement with oral corticosteroid treatment. Nevertheless, it only partially maintained the improvement so that topical corticosteroid treatment using a squirt system needs to be combined with intervals of short-term oral corticosteroids to treat steroid-dependent olfactory loss while avoiding the side effects of long-term oral corticosteroid use.

Radiofrequency inferior turbinate reduction: long-term olfactory and functional outcomes

OBJECTIVE

The aim of this study was to assess the long-term effects of radiofrequency inferior turbinate reduction (RITR) on nasal function in patients affected by nasal obstruction secondary to turbinate hypertrophy, focusing attention on increased sense of smell and its persistence after a 2-year follow-up.

STUDY DESIGN

Case series with planned data collection.

SETTING

ENT division, university hospital.

SUBJECTS AND METHODS

A total of 40 consecutive patients undergoing RITR for allergic or nonallergic chronic rhinitis with inferior turbinate hypertrophy were included. We planned a series of tests, including the "Sniffin' Sticks" test battery, anterior rhinomanometry, and the nasal Obstruction Symptom Evaluation (NOSE) scale, on the day of the procedure and at the 2-month and 2-year follow-up visits.

RESULTS

Of the 40 patients, 35 completed all the objective and subjective examinations on the day of the procedure and at the 2-month and 2-year follow-up visits. The authors found a significant decrease in nasal resistances from a mean of 1.13 Pa/cm(3)s(-1) preoperatively to a mean of 0.29 Pa/cm(3)s(-1) 2 years postoperatively and improvement in odor threshold, discrimination, and identification scores 2 years postoperatively. The NOSE score diminished significantly 2 years after surgery from a mean of 23.14 to a mean of 4.14 (all P < .01 with the t test for repeated measures).

CONCLUSION

This long-term evaluation showed that radiofrequency treatment for allergic or nonallergic inferior turbinate hypertrophy appeared to provide improvement in olfaction, decrease nasal resistances, and have subjective benefits, maintained 2 years after the procedure.

Radiofrequency inferior turbinate reduction: an evaluation of olfactory and respiratory function

OBJECTIVE

The aim of this study was to assess the outcomes after radiofrequency inferior turbinate reduction (RITR) on objective and subjective nasal function in patients with nasal obstruction caused by turbinate hypertrophy and to evaluate the possible effect on olfactory function.

STUDY DESIGN

Case series with planned data collection.

SETTING

ENT division, university hospital.

SUBJECTS AND METHODS

Forty consecutive patients who underwent RITR for allergic or nonallergic chronic rhinitis with inferior turbinate hypertrophy were tested before and two months after the surgical procedure, using the Sniffin' Sticks test battery, anterior rhinomanometry, and the nasal obstruction symptom evaluation (NOSE) scale.

RESULTS

The total basal nasal resistance at 150 Pa diminished significantly two months after surgery. Preoperative olfactory tests showed anosmia in five percent (n = 2) of the patients, hyposmia in 82 percent (n = 33), and normosmia in 12 percent (n = 5). At two months from the intervention, two percent (n = 1) were diagnosed as anosmic, 12 percent (n = 5) as hyposmic, and 85 percent (n = 34) as normosmic. The means of preoperative odor threshold (T), discrimination (D), identification (I), and the overall TDI score improved significantly postoperatively (P < 0.001). The NOSE score in the two-month follow-up improved in 97.5 percent (n = 39) of patients, with a mean difference in pre- vs. postintervention score of 40.12 (95% confidence interval 35.75-44.25; P < 0.001).

CONCLUSION

RITR may provide excellent outcomes in terms of improvement in olfactory function and nasal flow in patients affected by turbinate hypertrophy refractory to medical therapy.

Effects of typical inducers on olfactory xenobiotic-metabolizing enzyme, transporter, and transcription factor expression in rats

Several xenobiotic-metabolizing enzymes (XMEs) have been identified in the olfactory mucosa (OM) of mammals. However, the molecular mechanisms underlying the regulation of these enzymes have been little explored. In particular, information on the expression of the transcriptional factors in this tissue is quite limited. The aim of the present study was to examine the impact of five typical inducers, Aroclor 1254, 3-methylcholanthrene, dexamethasone, phenobarbital, and ethoxyquin, on the activities and mRNA expression of several XMEs in the OM and in the liver of rats. We also evaluated the effects of these treatments on the mRNA expression of transcription factors and transporters. On the whole, the intensities of the effects were lower in the OM than in the liver. Dexamethasone was found to be the most efficient treatment in the OM. Dexamethasone induced the transcription of several olfactory phase I, II, and III genes [such as cytochromes P450 2A3 and 3A9, UDP-glucuronosyltransferase (UGT) 2A1, and multidrug resistance-related protein type 1] and increased UGT activities. We observed that dexamethasone up-regulated sulfotransferase 1C1 expression in the OM but down-regulated it in the liver. Aroclor and ethoxyquin induced the gene expression of CYP1A and quinone reductase, respectively, in the OM. The transcription factors aryl hydrocarbon receptor, nuclear factor E2-related factor 2 (Nrf2), peroxisome proliferator-activated receptor α, pregnane X receptor, and glucocorticoid receptor were detected in the OM, but no constitutive androstane receptor expression was observed. Dexamethasone and Aroclor enhanced olfactory Nrf2 expression. These results demonstrate that olfactory XME can be modulated by chemicals and that the mechanisms involved in the regulation of these enzymes are tissue-specific.

Effects of traditional Chinese acupuncture in post-viral olfactory dysfunction

OBJECTIVE

To date, recovery of olfactory function after viral infection of the upper airway cannot be achieved reliably with pharmacotherapy. The aim of this study was to evaluate the effects of traditional Chinese acupuncture (TCA) on olfactory function in patients with persistent post-viral olfactory dysfunction (PVOD).

STUDY DESIGN

Historical cohort study.

SETTING

University Medical Center, Department of Otorhinolaryngology.

SUBJECTS AND METHODS

A total of 15 patients presenting to the outpatient clinic with PVOD were treated by TCA in 10 weekly, 30-minute sessions. Subjective olfactometry was performed with the Sniffin' Sticks test set. Treatment success was defined as an increase in Sniffin' Sticks test scores of at least six points. The effects of TCA, obtained with the chi(2) test, were compared with those of matched pairs suffering from PVOD who had been treated with vitamin B complex over 12 weeks.

RESULTS

Eight patients treated with TCA had improved olfactory function compared with two treated with vitamin B complex. chi(2) test revealed a significantly better outcome in olfactory function in patients undergoing acupuncture compared with patients receiving vitamin B complex (P = 0.02).

CONCLUSION

TCA possibly offers a new therapeutic regimen for post-viral dysosmia. More research in a larger case series is needed before a clearer picture will emerge.