Clinical assessment of patients with smell and taste disorders

Comparison of sinonasal symptoms in upper respiratory tract infections during the infectious diseases season of November 2023 to March 2024-a cross-sectional study

Introduction

Upper respiratory tract infections (URTIs) are among the most common reasons for patients consulting a general practitioner (GP) during the infectious diseases season, with viruses being the predominant cause. The COVID-19 pandemic has significantly impacted GPs' perception of these infections. The pandemic's progression, especially with the emergence of the Omicron variant, has complicated the diagnosis and treatment of URTIs, with evolving symptoms.

Aim

The aim of this study was to assess the differences in symptoms reported by patients with various infections, such as COVID-19, influenza, common cold, and post-viral rhinosinusitis, during the infectious diseases season of November 2023 to March 2024.

Materials and methods

The study was conducted in a primary health care clinic, providing care for a population of approximately 10,000 people, among adult patients presenting with URTI symptoms during the 2023/2024 infectious diseases season. Patients qualified for the study were swabbed for SARS-CoV-2, influenza A and B and respiratory syncytial virus (RSV) antigens. Symptoms were assessed with the use of a semi-structured questionnaire.

Results

Of the 1810 patients presenting with symptoms of URTIs, 276 patients were included in the study. Among patients with COVID-19, symptoms of nasal obstruction (p = 0.005) and nasal discharge (p = 0.001) were less common than in those with influenza or common cold. However, these nasal symptoms were significantly more frequent among patients with COVID-19 who had confirmed previous immunization (COVID-19 history or vaccination) (p = 0.028).

Conclusion

The incidence of individual sinonasal symptoms varies significantly depending on the aetiological agent of the URTI. This observation may not only help clinicians make the correct diagnosis, but also suggests an inflammatory response in the nasal mucosa and paranasal sinuses that is dependent on the aetiological agent. The study also indicates that this response is altered within the same virus species following immunization.

Limitations

The study's limitations include a small sample size (276 patients), focus on one season and one GP practice, and reliance on clinical signs and antigen tests. Nonetheless, the findings provide valuable insights. Further research with larger patient groups and extended follow-up periods is required to confirm these findings.

An fMRI-based investigation of the effects of odors on the functional connectivity network underlying the working memory

In the human brain, the regions responsible for emotion processing, motivation, and memory are heavily influenced by olfaction, whose neural pathway is directly exposed to the outer world. In this study, we used fMRI to examine how different olfactory conditions might affect the functional connectivity circuit underlying working memory in the brain. To this end, 30 adults (aged 20-35), 13 males and 17 females, with high educational levels were chosen. Participants were screened for potential olfactory issues before undergoing the Sniffin' sticks test, which was part of the inclusion criteria. Before imaging, each participant was given the required level of training and was then asked to complete four olfactory tests involving pleasant and unpleasant odors, air, and null stimulation. The results of Seed-based analysis suggested a function connection between the inferior parietal region and the left frontal pole region upon olfactory stimulation with vanilla scent in contrast to null stimulation in this comparison, ROI-based analysis revealed an inverse synchronous among the entorhinal cortex, orbitofrontal cortex, and dorsolateral prefrontal cortex (dlPFC). Both dlPFC and hippocampus were involved in olfactory discrimination between two different stimulants. Our findings indicate the presence of inverse correlations between several regions associated with olfaction and working memory, with pleasant scents leaving a stronger impact on the working memory-related areas, particularly the inferior parietal region.

Taste and Smell Alterations (TSAs) in Cancer Patients

Recently, smell and taste disorders have seen renewed interest, as these symptoms are frequent complications of SARS-CoV-2 infection, since approximately 60% of patients affected by COVID-19 have shown olfactory and gustatory alterations. Otolaryngology pays attention to taste and smell abnormalities (TSAs), especially when associated with oncology. TSAs are common symptoms in people affected by cancer, yet they are ignored and underestimated. The clinical outcome of TSAs in cancer evidences the importance of identifying them with chemotherapy or radiotherapy in general, and they are associated with many types of cancer. We recognize the findings of the literature on TSAs in cancer, evaluating how it is important to consider and identify these disorders concerning reduced food enjoyment or inappropriate nutrient intake, and modulating the nutritional status, quality of life, and impact of therapy. This review aims to critically evaluate and recognize the assessment and clinical perspectives of taste and smell disorders in a cancer population.

Structures and functions of the normal and injured human olfactory epithelium

The olfactory epithelium (OE) is directly exposed to environmental agents entering the nasal cavity, leaving OSNs prone to injury and degeneration. The causes of olfactory dysfunction are diverse and include head trauma, neurodegenerative diseases, and aging, but the main causes are chronic rhinosinusitis (CRS) and viral infections. In CRS and viral infections, reduced airflow due to local inflammation, inflammatory cytokine production, release of degranulated proteins from eosinophils, and cell injury lead to decreased olfactory function. It is well known that injury-induced loss of mature OSNs in the adult OE causes massive regeneration of new OSNs within a few months through the proliferation and differentiation of progenitor basal cells that are subsequently incorporated into olfactory neural circuits. Although normal olfactory function returns after injury in most cases, prolonged olfactory impairment and lack of improvement in olfactory function in some cases poses a major clinical problem. Persistent inflammation or severe injury in the OE results in morphological changes in the OE and respiratory epithelium and decreases the number of mature OSNs, resulting in irreversible loss of olfactory function. In this review, we discuss the histological structure and distribution of the human OE, and the pathogenesis of olfactory dysfunction associated with CRS and viral infection.

Investigating sensitivity to multi-domain prediction errors in chronic auditory phantom perception

The perception of a continuous phantom in a sensory domain in the absence of an external stimulus is explained as a maladaptive compensation of aberrant predictive coding, a proposed unified theory of brain functioning. If this were true, these changes would occur not only in the domain of the phantom percept but in other sensory domains as well. We confirm this hypothesis by using tinnitus (continuous phantom sound) as a model and probe the predictive coding mechanism using the established local-global oddball paradigm in both the auditory and visual domains. We observe that tinnitus patients are sensitive to changes in predictive coding not only in the auditory but also in the visual domain. We report changes in well-established components of event-related EEG such as the mismatch negativity. Furthermore, deviations in stimulus characteristics were correlated with the subjective tinnitus distress. These results provide an empirical confirmation that aberrant perceptions are a symptom of a higher-order systemic disorder transcending the domain of the percept.

Comparison of the incidence of smell and taste disorders between influenza and COVID-19

OBJECTIVE

Smell and taste disorders among patients with COVID-19 has become increasingly reported in the literature, however the prevalence varies. Post-infectious respiratory dysfunction has also been linked to influenza. In this study, we aimed to compare the rates of smell and taste disorders between COVID-19 and Influenza in unvaccinated patients.

STUDY DESIGN

Retrospective cohort study.

SETTING

TriNetX research network.

METHODS

Two queries were made on 7/1/2023 to include Influenza without a diagnosis of COVID-19 and a COVID-19 without a diagnosis of Influenza. The queries included patients from January 1 to December 31, 2022 from 102 Healthcare Organizations. The resultant population of patients with ICD-10 codes for COVID-19 and Influenza were matched using demographic characteristics to evaluate the risk of smell disorders.

RESULTS

The overall 3-month incidence of smell and taste disorders was 0.73 % in the COVID-19 population and 0.1 % in the influenza population. The 3-month matched risk ratios were 11.1 [95 % CI (8.8,13.8)]; p < 0.001) times higher for disorders of the smell and taste secondary to COVID-19 compared to influenza.

CONCLUSIONS

Disorders of the smell and taste are more common among patients with COVID-19 compared to patients with Influenza. Beyond smell loss, patients experience additional nasal and sinus-related rhinological symptoms, pointing to COVID-19's and influenza's wider impact on overall rhinological health. We believe that due to the transient nature of these disorders, they might go underreported.

Quantitive Assessment of Gustatory Function and Its Association with Demographics, and Systemic Morbidity

This study aimed to analyze the associations of gustatory dysfunction as measured by validated taste strips with demographics and co-morbidities. This cross-sectional study retrospectively analyzed records of patients who attended the Orofacial Chemosensory Center of Hadassah Medical Center between 2017 and 2020. Taste strips were used as a validated method to determine taste dysfunction. A total of 272 subjects were included, 137 (50.4%) women and 135 (49.6%) men, with a mean age of 53.5 ± 19.3 years and age range of 18-98 years. The total taste score among the study population was 8.53 ± 4.03 (scale range 0-16). Age had a significant negative correlation with the total taste score (p = 0.001), and men exhibited worse total (p < 0.001), salty (p = 0.003), and bitter (p < 0.001) scores. Major trauma was associated with worse total (p < 0.001) and specialized taste assessments (sweet (p = 0.001), sour (p = 0.002), salty (p = 0.016), and bitter (p < 0.001)). Chemotherapy was associated with reduced total (p < 0.001), salty (p = 0.003), and bitter (p = 0.001) taste scores. Zinc deficiency exhibited worse salty (p = 0.027) and total (p = 0.038) taste scores. Patients with burning mouth syndrome (BMS) showed higher salty scores (p = 0.017). Patients who experienced exposure to toxic chemicals exhibited worse salty scores (p = 0.024). We conclude that gustatory dysfunction is associated with older age, male sex, and co-morbidities of major trauma, current chemotherapy, zinc deficiency, BMS, and exposure to toxins. The study highlights the importance of systemic evaluation and quantitive gustatory dysfunction assessment as part of the diagnostic process of patients with subjective complaints of taste disorders.

Effect of Regular Consumption of a Miraculin-Based Food Supplement on Taste Perception and Nutritional Status in Malnourished Cancer Patients: A Triple-Blind, Randomized, Placebo-Controlled Clinical Trial-CLINMIR Pilot Protocol

Taste disorders are common among cancer patients undergoing chemotherapy, with a prevalence ranging from 20% to 86%, persisting throughout treatment. This condition leads to reduced food consumption, increasing the risk of malnutrition. Malnutrition is associated not only with worse treatment efficacy and poor disease prognosis but also with reduced functional status and quality of life. The fruit of Synsepalum dulcificum (Daniell), commonly known as miracle berry or miracle fruit, contains miraculin, a taste-modifying protein with profound effects on taste perception. The CLINMIR Protocol is a triple-blind, randomized, placebo-controlled clinical trial designed to evaluate the regular consumption of a food supplement containing a miraculin-based novel food, dried miracle berry (DMB), on the taste perception (measured through electrogustometry) and nutritional status (evaluated through the GLIM Criteria) of malnourished cancer patients under active antineoplastic treatment. To this end, a pilot study was designed with 30 randomized patients divided into three study arms (150 mg DMB + 150 mg freeze-dried strawberries, 300 mg DMB, or placebo) for three months. Throughout the five main visits, an exhaustive assessment of different parameters susceptible to improvement through regular consumption of the miraculin-based food supplement will be conducted, including electrical and chemical taste perception, smell perception, nutritional and morphofunctional assessment, diet, quality of life, the fatty acid profile of erythrocytes, levels of inflammatory and cancer-associated cytokines, oxidative stress, antioxidant defense system, plasma metabolomics, and saliva and stool microbiota. The primary anticipated result is that malnourished cancer patients with taste distortion who consume the miraculin-based food supplement will report an improvement in food taste perception. This improvement translates into increased food intake, thereby ameliorating their nutritional status and mitigating associated risks. Additionally, the study aims to pinpoint the optimal dosage that provides maximal benefits. The protocol adheres to the SPIRIT 2013 Statement, which provides evidence-based recommendations and is widely endorsed as an international standard for trial protocols. The clinical trial protocol has been registered at the platform for Clinical Trials (NCT05486260).

Assessment of COVID-19-related olfactory dysfunction and its association with psychological, neuropsychiatric, and cognitive symptoms

Purpose of review

To provide a detailed overview of the assessment of COVID-19-related olfactory dysfunction and its association with psychological, neuropsychiatric, and cognitive symptoms.

Recent findings

COVID-19-related olfactory dysfunction can have a detrimental impact to the quality of life of patients. Prior to the COVID-19 pandemic, olfactory and taste disorders were a common but under-rated, under-researched and under-treated sensory loss. The pandemic has exacerbated the current unmet need for accessing good healthcare for patients living with olfactory disorders and other symptoms secondary to COVID-19. This review thus explores the associations that COVID-19 has with psychological, neuropsychiatric, and cognitive symptoms, and provide a framework and rationale for the assessment of patients presenting with COVID-19 olfactory dysfunction.

Summary

Acute COVID-19 infection and long COVID is not solely a disease of the respiratory and vascular systems. These two conditions have strong associations with psychological, neuropsychiatric, and cognitive symptoms. A systematic approach with history taking and examination particularly with nasal endoscopy can determine the impact that this has on the patient. Specific olfactory disorder questionnaires can demonstrate the impact on quality of life, while psychophysical testing can objectively assess and monitor olfaction over time. The role of cross-sectional imaging is not yet described for COVID-19-related olfactory dysfunction. Management options are limited to conservative adjunctive measures, with some medical therapies described.

Olfactory Dysfunction following COVID-19 and the Potential Benefits of Olfactory Training

COVID-19 is associated with a common symptom of olfactory dysfunction, which may persist even after the infection is resolved. Olfactory training (OT) has emerged as the most effective intervention for post-viral olfactory dysfunction. OT involves daily exposure of the olfactory system to various odors. The current study aims to explore olfactory dysfunction following COVID-19 and the potential benefits of olfactory training.

METHODS

This is a cross-sectional study conducted among adults aged 18-60 living in Alahssa, Saudi Arabia. An online questionnaire containing an informed consent form and a survey to collect demographic data, vaccination status, level of loss of smell and taste, and the level of awareness about olfactory training (OT) was distributed among all participants who agreed to participate in this study.

RESULTS

The study included 524 participants and presented their baseline characteristics, including age, gender, COVID-19 infection status, and complaints. Most patients were female (66.0%), and 46.2% had previously been infected with COVID-19. About 54.8% of participants reported chemosensory dysfunction, while 286 had olfactory dysfunction. Of those, 29.8% had anosmia, 16.8% had hyposmia, and 8.0% had parosmia. Results suggest that being fully or partially vaccinated may offer some protection against olfactory dysfunction compared to being unvaccinated. Adherence to olfactory training was associated with improvement in the sense of smell.

CONCLUSIONS

The study highlights the importance of awareness and adherence to olfactory training, which may improve the sense of smell in individuals with chemosensory dysfunction. The findings of this study can inform public health policies and interventions aimed at reducing the burden of olfactory dysfunction associated with COVID-19 vaccination.

Can photobiomodulation restore anosmia and ageusia induced by COVID-19? A pilot clinical study

Along with other COVID-19 clinical manifestations, management of both olfactory and gustatory dysfunction have drawn a considerable attention. Photobiomodulation (PBM) has emerged to be a possible effective therapy in restoring taste and smell functionality, but the evidence is scarce. Hence, the present pilot study is aimed to evaluate the effectiveness of intranasal and intraoral PBM administrations in management of anosmia and ageusia respectively. Twenty Caucasian subjects who diagnosed with anosmia and ageusia were recruited. Visual analogue scale was utilised to evaluate patients' self-reported for both olfactory and gustatory functionality. The laser-PBM parameters and treatment protocols for anosmia and ageusia were as follows respectively: 660 nm, 100 mW, two points intranasally, 60 J/session, 12 sessions; dual wavelengths (660 nm and 808 nm), 100 mW, three points intraorally, 216 J/session, 12 sessions. Our results showed a significant functionality improvement of both olfactory and gustatory functionality. Extensive studies with large data and long-term follow-up period are warranted.

Association of air pollution with olfactory identification performance of São Paulo residents: a cross-sectional study

OBJECTIVE

Exposure to particulate matter of 10 μm or less in diameter (PM₁₀) has been implicated in pulmonary and cardiovascular diseases. However, the effect of PM₁₀ on olfaction has not been well established. We estimated individual acute and chronic PM₁₀ exposure levels in a large Brazilian cohort and related them to the ability to identify odors.

METHODS

Adults from São Paulo (n = 1358) were recruited from areas with different levels of air pollution. To verify individual exposure to air pollution, the averages of 30, 60, 90, 180 and 364 days of PM₁₀ were interpolated to subjects' zip codes using the kriging method. Olfactory identification performance was tested using the University of Pennsylvania Smell Identification Test (UPSIT®). Multiple linear regressions were used to calculate the effect of air pollution on olfactory identification performance, controlling for demographic and other variables that affect the sense of smell.

RESULTS

Acute exposures to PM₁₀ were related to worse UPSIT® scores, including 30- (β =  - 0.94, 95% Confidence Interval [CI]  - 0.98,  - 0.89), 60- (β =  - 1.09, 95% CI = - 1.13,  - 1.04) and 90-day intervals (β =  - 1.06, 95% CI  - 1.10,  - 1.02) (reference for β: 1 µm/m³ increase in PM10 exposure per point decrease in UPSIT® score). Chronic exposures were also associated with worse olfaction for both 180- (β =  - 1.06, 95% CI  - 1.10,  - 1.03) and 364-day (β =  - 0.87, 95% CI  - 0.90,  - 0.84) intervals. As in prior work, men, older, low-income, and low-schooling people demonstrated worse olfactory performance.

CONCLUSION

Acute and chronic exposure to PM₁₀ is strongly associated with olfactory identification performance in Brazilian adults. Understanding the mechanisms which underlie these relationships could help to improve chemosensory function with a large public health impact.

Taste and Smell Disorders in Cancer Treatment: Results from an Integrative Rapid Systematic Review

Taste and smell disorders (TSDs) are common side effects in patients undergoing cancer treatments. Knowing which treatments specifically cause them is crucial to improve patients' quality of life. This review looked at the oncological treatments that cause taste and smell alterations and their time of onset. We performed an integrative rapid review. The PubMed, PROSPERO, and Web of Science databases were searched in November 2022. The article screening and study selection were conducted independently by two reviewers. Data were analyzed narratively. Fourteen studies met the inclusion criteria and were included. A high heterogeneity was detected. Taste disorders ranged between 17 and 86%, while dysosmia ranged between 8 and 45%. Docetaxel, paclitaxel, nab-paclitaxel, capecitabine, cyclophosphamide, epirubicin, anthracyclines, and oral 5-FU analogues were found to be the drugs most frequently associated with TSDs. This review identifies the cancer treatments that mainly lead to taste and smell changes and provides evidence for wider studies, including those focusing on prevention. Further studies are warranted to make conclusive indication possible.

Taste and smell abnormalities in advanced cancer: Negative impact on subjective food intake

BACKGROUND

Taste and smell abnormalities (TSAs) are present in all cancer stages and may contribute to malnutrition. Despite this, they are rarely screened for. This study examined the prevalence and characteristics of TSAs and their influence on subjective food intake in advanced cancer.

METHODS

Consecutive patients with advanced cancer were recruited. A modified Taste and Smell Survey assessed subjective TSAs. Objective TSAs were assessed with validated taste strips and "Sniffin Sticks." A six-item food intake questionnaire identified any effect TSAs had on food preferences/aversions. Nutrition status was evaluated with the abridged Patient-Generated Subjective Global Assessment.

RESULTS

All 30 participants had either subjective or objective TSAs. The prevalence of TSAs varied based on the assessment tool used. Participants were more aware of taste changes (TCs) than smell changes (SCs). TCs caused reduced food intake in 13 participants. Six reported SCs affected food intake. Food choices caused by TSAs were inconsistent. Some foods preferred because of TSAs were avoided by other participants. None received nutrition counseling on TSA management. Almost all were at malnutrition risk (97%). Almost half (47%) felt TSAs reduced quality of life (QoL). Participants reported "not looking forward to meals" and "can't sit down and eat anything" because of TSAs.

CONCLUSION

TSAs were highly prevalent and impactful on food intake. Both TCs and SCs were complex and varied on an individual basis. Despite the effect on health and QoL, no patients received any nutrition counseling on TSA management. Individualized screening and advice are needed for TSAs in advanced cancer.

Pathophysiology of SARS-CoV-2 Infection of Nasal Respiratory and Olfactory Epithelia and Its Clinical Impact

PURPOSE OF REVIEW

While the predominant cause for morbidity and mortality with SARS-CoV-2 infection is the lower respiratory tract manifestations of the disease, the effects of SARS-CoV-2 infection on the sinonasal tract have also come to the forefront especially with the increased recognition of olfactory symptom. This review presents a comprehensive summary of the mechanisms of action of the SARS-CoV-2 virus, sinonasal pathophysiology of COVID-19, and the correlation with the clinical and epidemiological impact on olfactory dysfunction.

RECENT FINDINGS

ACE2 and TMPRSS2 receptors are key players in the mechanism of infection of SARS-CoV-2. They are present within both the nasal respiratory as well as olfactory epithelia. There are however differences in susceptibility between different groups of individuals, as well as between the different SARS-CoV-2 variants. The sinonasal cavity is an important route for SARS-CoV-2 infection. While the mechanism of infection of SARS-CoV-2 in nasal respiratory and olfactory epithelia is similar, there exist small but significant differences in the susceptibility of these epithelia and consequently clinical manifestations of the disease. Understanding the differences and nuances in sinonasal pathophysiology in COVID-19 would allow the clinician to predict and counsel patients suffering from COVID-19. Future research into molecular pathways and cytokine responses at different stages of infection and different variants of SARS-CoV-2 would evaluate the individual clinical phenotype, prognosis, and possibly response to vaccines and therapeutics.

Investigations and Outcomes for Olfactory Disorders

Purpose of Review

To provide a detailed overview of the investigations and core outcome measures for olfactory disorders.

Recent Findings

Olfactory disorders can have a detrimental impact to the quality of life of patients. There are a wide range of causes of olfactory loss including sinonasal conditions, idiopathic, post-head trauma or infection. This review highlights the key investigations and reasoning for their use to clinically assess and research patients with olfactory disorders. In addition, this review outlines the core outcome measures for olfaction that will help inform future research in olfactory disorders.

Summary

A systematic approach with history taking and examination particularly with nasal endoscopy can determine the cause of the olfactory disorder in most cases. Specific olfactory disorder questionnaires can demonstrate the impact on quality of life, while psychophysical testing can objectively assess and monitor olfaction over time. Olfactory-evoked potentials and functional MRI are reserved for research, whereas CT and MRI imaging are used depending on history and examination. A core outcome set for olfaction has been developed that will help standardise the outcome measures used in olfaction and olfactory disorders research.

Olfactory dysfunction in type II diabetes: Therapeutic options and lessons learned from other etiologies - A scoping review

INTRODUCTION

Olfactory dysfunction (OD) is highly prevalent amongst type 2 diabetes mellitus (DM2) patients and has many associated health risks. For example, OD can lead to poor nutrition, safety issues related to diminished hazard detection, and increased mortality rates. While limited research exists about therapeutics for DM2-associated OD, recovery of olfactory function is better studied in other pathologic states. The objectives of this scoping review are to synthesize the existing data on interventions for DM2-associated OD and present the evidence for therapies that have been utilized for non-DM2-associated causes of OD. Additionally, the potential therapeutic opportunities for patients with DM2 are explored.

METHODS

A scoping review was conducted with a medical librarian to identify studies investigating treatments of DM2-related OD. 6 databases were searched (Embase, CINAHL, the Cochrane Library, Google Scholar, OVID Medline, and Web of Science). Studies were eligible if the primary discussion involved treatment of olfactory deficits in the context of DM2. All publication dates were included, and studies published in languages other than English were excluded.

RESULTS

3631 articles were identified; 3 articles met inclusion criteria and underwent full text review. Hyperbaric oxygen (HBO), the DPP-4 inhibitor Linagliptin and the GLP-1 agonists Exenatide and Liraglutide are the only therapeutics that have been used in the context of DM2. Only HBO and GLP-1 agonists produced statistically significant improvements in olfactory identification. The literature regarding non-DM2-associated OD supports interventions such as olfactory training, dietary supplements, and intranasal insulin. Specifically, olfactory training was very effective in many contexts such as post-viral and traumatic OD while being affordable and non-invasive.

CONCLUSION

This scoping review of olfactory rehabilitation options for DM2-induced OD demonstrates a paucity of prospective investigations of plausible therapeutics. Additionally, treatments for OD related to non-DM2-associated etiologies, such as olfactory training, are well-studied, efficacious, and should be investigated in the context of DM2. Future investigation has the potential to enhance the quality of clinical intervention for OD and improve short- and long-term outcomes for DM2 patients.

Testing for anosmia and ageusia in patients presenting to the emergency department with suspected coronavirus disease 2019 in Saudi Arabia

Objective

This study investigated the role of objective olfactory dysfunction (OD) and gustatory dysfunction (GD) testing among patients with suspected coronavirus disease 2019 (COVID-19) who presented with respiratory symptoms.

Methods

A prospective, blinded, observational study was conducted in the emergency units of two tertiary hospitals. Participants were asked to identify scents in the pocket smell test (PST) and flavors in four different solutions in the gustatory dysfunction test (GDT). We assessed the level of agreement between objective findings and self-reported symptoms. We evaluated the diagnostic accuracy of chemosensory dysfunction for diagnosing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Results

Of 250 participants, 74 (29.6%) were SARS-CoV-2-positive. There was slight agreement between self-reported symptoms and objective findings (kappa = 0.13 and 0.10 for OD and GD, respectively). OD assessed by the PST was independently associated with COVID-19 (adjusted odds ratio = 1.89, 95% confidence interval, 1.04–3.46). This association was stronger when OD was combined with objective GD, cough, and fever (adjusted odds ratio = 7.33, 95% confidence interval, 1.17–45.84).

Conclusions

Neither the PST nor GDT alone are useful screening tools for COVID-19. However, a diagnostic scale based on objective OD, GD, fever, and cough may help triage patients with suspected COVID-19.

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.

Psychophysical chemosensory dysfunction in eating disorders: a qualitative systematic review

PURPOSE

Patients with chemosensory dysfunction experience significant quality of life disruptions, including reduced enjoyment of eating. While chemosensory dysfunction has been associated with eating disorders, the relationship is poorly understood. This systematic review aims to characterize psychophysical gustation and olfaction in patients with eating disorders.

METHODS

Systematic review of investigations assessing psychophysical chemosensory function in patients with organic eating disorders.

RESULTS

26 studies were included. Five studies assessed both chemosenses, while 12 and 9 assessed exclusively gustation or olfaction, respectively. In total, 779 patients were included [72.4% anorexia nervosa (AN), 26.7% bulimia nervosa (BN), 0.8% combined AN/BN]. Patients with eating disorders experienced rates of hypogeusia up to 87% in AN and 84.6% in BN. There was evidence for alterations in psychophysical olfaction, but orientation of trends were less clear. Chemosensory dysfunction was more evident in AN patients. Treatment correlated with improved chemosensory function.

CONCLUSIONS

Despite heterogeneity in study methodology and results, this review demonstrates that patients with eating disorders experience some degree of chemosensory dysfunction, particularly in gustation. This symptomatology overlaps with those experienced by patients with other causes of chemosensory impairment. These findings suggest potential broad psychosocial, dietary, and mental health implications in patient populations experiencing chemosensory dysfunction.

LEVEL OF EVIDENCE

Level II.

Restoration of olfactory dysfunctions by nanomaterials and stem cells-based therapies: Current status and future perspectives

Dysfunction in the olfactory system of a person can have adverse effects on their health and quality of life. It can even increase mortality among individuals. Olfactory dysfunction is related to many factors, including post-viral upper respiratory infection, head trauma, and neurodegenerative disorders. Although some clinical therapies such as steroids and olfactory training are already available, their effectiveness is limited and controversial. Recent research in the field of therapeutic nanoparticles and stem cells has shown the regeneration of dysfunctional olfactory systems. Thus, we are motivated to highlight these regenerative approaches. For this, we first introduce the anatomical characteristics of the olfactory pathway, then detail various pathological factors related to olfactory dysfunctions and current treatments, and then finally discuss the recent regenerative endeavors, with particular focus on nanoparticle-based drug delivery systems and stem cells. This review offers insights into the development of future therapeutic approaches to restore and regenerate dysfunctional olfactory systems.

Bilateral Nervus Intermedius Sectioning for Geniculate Neuralgia: Case Report and Operative Video

BACKGROUND AND IMPORTANCE

Geniculate neuralgia is a rare condition characterized by excruciating ear pain. Surgical options for geniculate neuralgia include microvascular decompression and sectioning of the nervus intermedius. We report herein a case of bilateral geniculate neuralgia treated by nervus intermedius sectioning without prior microvascular decompression. To our knowledge, this is the first report of this treatment strategy with a subsequent description of the side effects of bilateral nervus intermedius disruption.

CLINICAL PRESENTATION

A 54-yr-old woman presented with bilateral geniculate neuralgia, worse on the left, refractory to medical therapy. Surgical treatment options were reviewed, including microvascular decompression and sectioning of the nervus intermedius. She opted for left nervus intermedius sectioning. The procedure was uncomplicated and no compressive vascular loop was identified during surgery. Postoperatively, she had complete symptom resolution with no discernable side effects. Three years later, the patient developed worsening geniculate neuralgia on the contralateral side. After the discussion of treatment options, she opted again for sectioning of the contralateral nervus intermedius with successful resolution of all symptoms after surgery. Following surgery, the patient identified partial impairment of lacrimation and gustation. She continued to have functional taste of the anterior two-thirds of the tongue, lacrimation, and hearing bilaterally.

CONCLUSION

Bilateral sectioning of nervus intermedius may provide benefit in patients with bilateral geniculate neuralgia without egregious side effects. However, lacrimatory and gustatory alterations are a potentially significant side effect with a wide range of symptomatology.

Olfactory dysfunction in primary Sjogren's syndrome and its correlation with dry eye

Objective

To evaluate the olfactory function in primary Sjögren’s syndrome (pSS) patients and investigate its correlation with dry eye parameters.

Methods

Thirty-eight pSS patients (49.47 ± 10.06 years) and 20 healthy volunteers (47.40 ± 8.92 years) were enrolled in the study. All participants underwent ENT and eye examinations including a modified Connecticut Chemosensory Clinical Research Center (CCCRC) test, tear break-up time (TBUT), ocular surface staining (OSS) and Schirmer test. The parameters were compared between the two groups using Student-t test, and Pearson test was used to evaluate the correlations.

Results

Mean Schirmer and TBUT values were 2.39 ± 1.48 mm/5 min and 3.66 ± 1.5 sec in pSS and 18.30 ± 6.16 mm/5 min and 14.60 ± 3.64 sec in healthy subjects (p < 0.001, both). There was a significant decrease in mean odour threshold, odour identification, CCCRC and VAS scores in the pSS group (p < 0.001). Dry eye parameters showed moderate correlations with CCCRC parameters (r = 0.4-0.6, p < 0.001) and olfaction VAS score (r = 0.4-0.75, p < 0.05).

Conclusions

There is a mild clinical impairment in smell sense in patients with pSS which seems to be correlated with dry eye parameters. Therefore, smell complaints should be queried in pSS patients suffering from severe dry eye.

Transitioning the eating experience in survivors of head and neck cancer

PURPOSE

Applying the Social Cognitive Transition (SCT) Model of Adjustment as an interpretive framework, this mixed-methods case series explored how head and neck cancer (HNC) survivors participate in the dimensions of the eating experience (described as physiological, psychological, social, cultural).

METHODS

This was a sub-study of a primary study, "The Natural History and Impact of Taste Change in Oncology Care." Qualitative interviews and quantitative data (questionnaires and exams) were intersected to examine and describe the complexities of transitioning the eating experience after treatment for HNC. Triangulation of qualitative and quantitative data within and across cases was examined to produce rich descriptions of the changes and transitions in the eating experience.

RESULTS

Four case studies were detailed. All reported some taste and/or smell changes. Each case described worry about weight loss and the decreased ability to engage and finding meaning in the eating experience. Each expressed coping strategies that drew upon the social and cultural dimensions of their prior eating experience that brought meaning and purpose to the post-treatment eating experience.

CONCLUSIONS

This case series explored the impact of taste and oral function and the participant's pre- and post-treatment mental model of the eating experience. Application of the SCT Model of Adjustment to the eating experience in adults with HNC provided a deeper insight into how cognitive adaptation and coping strategies supported transition in identity related to the eating experience following cancer therapy.

The Etiologies and Considerations of Dysgeusia: A Review of Literature

BACKGROUND

Dysgeusia is a prevalent qualitative gustatory impairment that may affect food intake and quality of life. The facial (VII), glossopharyngeal (IX), and vagus (X) nerves are the three cranial nerves responsible for sensing taste. Typically, dysgeusia is considered a general term for all taste disorders. In addition, dysgeusia may be a symptom of underlying systemic conditions such as diabetes mellitus, chronic kidney disease, respiratory infections, and nutritional deficiencies. Various subjective and objective diagnostic approaches are available to aid clinicians, each with its own set of benefits and drawbacks.

HIGHLIGHTS

Taste impairment can lead to a lack of enjoyment while eating, food aversion, and malnutrition, resulting in a decrease in the quality of life and loss of muscle mass. Therefore, the present review aims to address the probable etiologies, diagnostic aids, and management of dysgeusia. A broad search for studies was conducted using PubMed, Web of Science, Scopus, and Google Scholar. In addition, relevant studies found in the references of the selected articles were also studied.

CONCLUSION

Oral health care providers should be aware of the possible etiologies of dysgeusia, diagnostic tools, and treatment options. Accurate diagnosis of the cause of taste dysfunction has a significant impact on the management of taste impairment.

SELF-REPORTED OLFACTORY, GUSTATORY AND OTOLOGIC DYSFUNCTIONS AMONG COVID-19 POSITIVE ADULTS IN NIGERIA- A PRELIMINARY REPORT

INTRODUCTION

The pathophysiology of COVID-19 is evolving. We investigated self-reported sudden loss of sense of smell and taste, and otologic disorders among COVID-19 patients.

METHODS

This was a case-control olfaction, gustation and otology study of COVID-19 RT-PCR tested adults. The study took place at the isolation centres for COVID-19 positive individuals in Abuja and Ibadan, among the epicentres of the disease in Nigeria. The participants were 46 COVID-19 positive adults and 46 COVID-19 negative adults. They responded to a validated online questionnaire-based on olfactory, gustatory and auditory loss. Chi-square tests and correlation analysis was done. Level of significance was at P<0.05.

RESULTS

Among cases, sudden loss of smell, taste and hearing were reported by 14 (30.4%), 8 (17.4%) and 5 (10.9%) cases respectively during the COVID- 19 infection. First symptom was loss of smell in 7 (15.2%) and loss of taste in 2 (4.3%) cases. The controls did not present with any of the symptoms. There was no significant correlation between loss of smell and age (r = 0.023, p=0.879); sex (r = -0.132, p=0.382) and co-morbidities (r = -0.028, p = 0.857). Similarly, there was no significant correlation between loss of taste and age (r = 0.052, p = 0.732); sex (0.040, p = 0.792) and co-morbidities (r = -0.014, p = 0.925).

CONCLUSION

Sudden loss of smell and taste are commoner among COVID - 19 positive adults than those without the infection in Nigeria. There is evidence of associated reduction in hearing acuity but further study with objective audiometric testing is recommended.

Smell and Taste in Severe CoViD-19: Self-Reported vs. Testing

One of the most striking reported symptoms in CoViD-19 is loss of smell and taste. The frequency of these impairments and their specificity as a potential central nervous system function biomarker are of great interest as a diagnostic clue for CoViD-19 infection as opposed to other similar symptomatologic diseases and because of their implication in viral pathogenesis. Here severe CoViD-19 was investigated by comparing self-report vs. testing of smell and taste, thus the objective severity of olfactory impairment and their possible correlation with other symptoms. Because a significant discrepancy between smell and taste testing vs. self-report results (p < 0.001) emerges in our result, we performed a statistical analysis highlighting disagreement among normosmia (p < 0.05), hyposmia, severe hyposmia, and anosmia (p < 0.001) and, in hypogeusia and severe hypogeusia, while no differences are observed in normogeusia and ageusia. Therefore, we analyzed the olfactory threshold by an objective test revealing the distribution of hyposmic (34%), severe hyposmic (48%), and anosmic (13%) patients in severe CoViD-19. In severe CoViD-19 patients, taste is lost in 4.3% of normosmic individuals, 31.9% of hyposmic individuals, 46.8% of severe hyposmic individuals, and 17% of anosmic individuals. Moreover, 95% of 100 CoViD-19 patients objectively tested were affected by smell dysfunction, while 47% were affected by taste dysfunction. Furthermore, analysis by objective testing also highlighted that the severity of smell dysfunction in CoViD-19 subjects did not correlate with age and sex. In conclusion, we report by objective testing that the majority of CoViD-19 patients report severe anosmia, that most of the subjects have olfactory impairment rather than taste impairment, and, finally, that the olfactory impairment correlate with symptom onset and hospitalization (p < 0.05). Patients who exhibit severe olfactory impairment had been hospitalized for about a week from symptom onset; double time has taken place in subjects with normosmia. Our results may be limited by the relatively small number of study participants, but these suggest by objective testing that hyposmia, severe hyposmia, and anosmia may relate directly to infection severity and neurological damage. The smell test assessment could be a potential screening symptom that might contribute to the decision to test suspected cases or guide quarantine instructions, further therapeutic approach, and evaluation of neurological damage.

Olfactory Dysfunction in a Mexican Population Outside of COVID-19 Pandemic: Prevalence and Associated Factors (the OLFAMEX Study)

PURPOSE OF REVIEW

To study the prevalence of olfactory loss and its associated factors in a Mexican population a cross-sectional analytical study based on a population interviewed about health, epidemiologic aspects, and sense of smell (tested with four scents: rose, banana, perfume, and gas) was conducted to evaluate olfactory detection, memory, and identification. Levels of sense of smell perception were determined when the participants detected, recognized, or identified all (normosmia), 1-3 (hyposmia), or none (anosmia) of the odorants. Associated factors of olfactory dysfunction were identified by multivariate analysis (odds ratio, 95%CI).

RECENT FINDINGS

Olfactory dysfunction is a prevalent disorder affecting up to 20% of the general population. In addition to viral infection, including COVID-19, a number of other causes and factors may also be involved. 1,956 surveys were conducted and 1,921 were analyzed. Most of the participants (62.1%) were women. The general prevalence of olfactory dysfunction, regarding detection, was 7.2% (7.1% hyposmia, 0.1% anosmia). Age-related olfactory deterioration was observed in both sexes from the 5th decade of life (OR 2.74, p = 0.0050). Women showed better olfactory identification (OR 0.73, p = 0.0010). Obesity (OR 1.97, p = 0.0070), low educational level, bad/very bad self-perceived olfactory function (OR 2.74, p = 0.0050), olfactory loss for less than one week (OR 1.35, p = 0.0030), exposure to toxics/irritants (OR 1.31, p = 0.0030), active smoking (OR 1.58, p < 0.0010), and type 2 diabetes mellitus (OR 2.68, 95%CI 1.74-4.10, p < 0.0001) were identified as factors associated with olfactory dysfunction. These results in a Mexican population suggest better olfactory identification (verbalization) in females. Age was a determining factor in the olfactory deterioration process and obesity and diabetes mellitus were also associated with olfactory disorders. Finally, these findings reinforce the differential diagnosis with other potential causes of sense of smell loss, during the COVID-19 outbreak.

Taste and smell disturbances in cancer patients: a scoping review of available treatments

PURPOSE

Taste and smell disturbances in patients affected by cancer are very common, but often under-recognized symptoms. If not addressed properly, they may impact nutritional status, food enjoyment, and quality of life. Treatment tools available for clinicians to manage chemosensory alterations are limited and are often based on personal clinical experiences. The aim of this study was to assess current oncological and palliative care literature through a scoping review, in order to identify available treatments for taste and smell alterations in cancer patients.

METHODS

Medline, Embase, CINAHL, ProQuest Dissertations and Theses, and Google Scholar were searched from inception until January 2020, with subject headings relevant to the domains of chemosensory alterations, palliative, and cancer care. A total of 10,718 English and French language publications were reviewed, yielding 43 articles on the researched topic.

RESULTS

The heterogeneity of selected articles led to difficulties in interpretation and analysis of the available evidence. Included publications differed in study design, population sample, anticancer treatments, and measures of assessment for taste and smell disturbances. A broad variety of treatment options were described including zinc and polaprezinc, radio-protectors, vitamins and supplements, anti-xerostomia agents, active swallowing exercises, nutritional interventions, delta-9-tetrahydrocannabinol, and photobiomodulation.

CONCLUSION

This scoping review identifies the current state of knowledge regarding chemosensory alterations within supportive cancer care. Despite not reaching firm conclusions, this article offers therapeutic venues to further explore in larger and more methodologically sound studies.

Diffusion tensor imaging: a smart move to olfactory pathway imaging; comparative study of chronic sinonasal polyposis patients and normal control

Background

Olfaction is critically important for a good quality of life and incorporated in many physiological domains such as attention, emotion, memory, and airflow motor control. Olfactory researches have been expanded in the last decade due to close relation between the olfactory disorders and different brain diseases. Diagnosis of anosmia and hyposmia are based on history, smell tests, and physical examination which rely on the patient’s response without an objective measure of impairment. This study assessed the value of volumetry and DTI parameters as objective measurements for olfactory dysfunction.

Fourteen patients with chronic sinonasal polyposis for at least 6 months were included in this study; all of them underwent tailored MRI examination including volumetry and DTI for olfactory bulbs and tracts. The results were compared to the same number of age and sex-matched healthy control group.

Results

The study results showed that olfactory bulb and tract (OB/T) volume, FA and ADC could distinguish between patients and healthy controls. Statistically significant differences were noticed between the FA & ADC values of patient and control groups (p < 0.05) and a highly significant one was noticed as regarding the OT volume (p < 0.001).

Conclusion

MR volumetry and DTI parameters can be used as objective measurements for the olfactory dysfunction for patients with chronic sinonasal polyposis.

Cell-Based Therapy Restores Olfactory Function in an Inducible Model of Hyposmia

Stem cell-based therapies have been proposed as a strategy to replace damaged tissues, especially in the nervous system. A primary sensory modality, olfaction, is impaired in 12% of the US population, but lacks treatment options. We report here the development of a novel mouse model of inducible hyposmia and demonstrate that purified tissue-specific stem cells delivered intranasally engraft to produce olfactory neurons, achieving recovery of function. Adult mice were rendered hyposmic by conditional deletion of the ciliopathy-related IFT88 gene in the olfactory sensory neuron lineage and following experimentally induced olfactory injury, received either vehicle or stem cell infusion intranasally. Engraftment-derived olfactory neurons were identified histologically, and functional improvements were measured via electrophysiology and behavioral assay. We further explored mechanisms in culture that promote expansion of engraftment-competent adult olfactory basal progenitor cells. These findings provide a basis for translational research on propagating adult tissue-specific sensory progenitor cells and testing their therapeutic potential.

•

A novel mouse model of inducible olfactory loss was used to test stem cell therapy

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Purified adult tissue-specific stem cells can engraft and restore olfaction

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Culture expansion of engraftment-competent stem cells was examined via RNA-seq

Subjective and Objective Assessment of Taste and Smell Sensation in Advanced Cancer

Context:

Taste and smell abnormalities (TSA) occur throughout the cancer trajectory regardless of cancer primary site and contribute to cancer-associated malnutrition. TSA etiology is poorly understood. Tumor-related inflammation is a possible cause.

Objective:

This study examined the prevalence, characteristics, and severity of TSA in advanced cancer and explored the relationship between TSA and nutritional status. No previous study combined subjective and objective measures for both taste and smell assessment in this population.

Method:

Consecutive advanced cancer hospice patients were recruited. A modified version of the “Taste and Smell Survey” assessed subjective TSA. Validated taste strips and “Sniffin’ Sticks” were the objective measures. The abridged patient-generated subjective global assessment evaluated nutritional status.

Results:

A 93% prevalence of TSA in 30 patients with advanced cancer was identified. When subjective and objective evaluations were combined, 28 had taste abnormalities, 24 smell abnormalities, and 24 both. Taste changes included “persistent bad taste” (n = 18) and changes in how basic tastes were perceived. Half reported smell was not “as strong” as prediagnosis, while more than half (n = 16) had an objective smell abnormality. Most (97%) were at risk of malnutrition. Fatigue, dry mouth, early satiety, and anorexia were common nutrition-impact symptoms. No statistically significant relationship was found between TSA and malnutrition scores.

Conclusions:

TSA were highly prevalent. Subjective taste and smell changes did not always accord with objective TSA, suggesting both assessments are valuable. TSA characteristics varied, and particular foods tasted and smelled different and were not enjoyed as before. TSA are common, high-impact problems in advanced cancer.

Diseases of the nasal cavity

Despite garnering minimal attention from the medical community overall, olfaction is indisputably critical in the manner in which we as humans interact with our surrounding environment. As the initial anatomical structure in the olfactory pathway, the nasal airway plays a crucial role in the transmission and perception of olfactory stimuli. The goal of this chapter is to provide a comprehensive overview of olfactory disturbances as it pertains to the sinonasal airway. This comprises an in-depth discussion of clinically relevant nasal olfactory anatomy and physiology, classification systems of olfactory disturbance, as well as the various etiologies and pathophysiologic mechanisms giving rise to this important disease entity. A systematic clinical approach to the diagnosis and clinical workup of olfactory disturbances is also provided in addition to an extensive review of the medical and surgical therapeutic modalities currently available.

Evaluation of the Olfactory Function With the "Sniffin' Sticks" Test After Endoscopic Transsphenoidal Pituitary Surgery

The aim of this study was to evaluate the olfactory function of patients who had undergone endoscopic transsphenoidal pituitary surgery. In this prospective study, the "Sniffin' Sticks" test was performed between June 2016 and April 2017 at Izmir Katip Celebi University Ataturk Training and Research Hospital. Thirty patients who were scheduled to undergo endoscopic transsphenoidal pituitary surgery were evaluated preoperatively and 8 weeks postoperatively using the Sniffin' Sticks test battery for olfactory function, odor threshold, smell discrimination, and odor identification. The patients were evaluated preoperatively by an otolaryngologist. The patients' demographic data and olfactory functions were analyzed with a t test and Wilcoxon-labeled sequential test. The study group comprised 14 women (46.7%) and 16 men (53.3%) patients. The mean age of the patients was 37.50 ± 9.43 years (range: 16-53 years). We found a significant difference in the preoperative and postoperative values of the odor recognition test (P = 0.017); however, there was no significant difference between the preoperative and postoperative odor threshold values (P = 0.172) and odor discrimination values (P = 0.624). The threshold discrimination identification test scores were not significant (P = 0.110). The olfactory function of patients who were normosmic preoperatively was not affected postoperatively. This study shows that the endoscopic transsphenoidal technique for pituitary surgery without nasal flap has no negative effect on the olfactory function.

The Important Role of Carbohydrates in the Flavor, Function, and Formulation of Oral Nutritional Supplements

Patients who are malnourished or at-risk for malnutrition often benefit from the consumption of oral nutritional supplements (ONS). ONS supply a range of micro- and macro-nutrients, and they can be used to supplement a diet or provide total nutrition. Since ONS are specially formulated products, all ONS ingredients—including carbohydrates—are added ingredients. This may seem to be at odds with the growing public health discourse on the need to reduce “added sugars” in the diet. However, carbohydrate is an essential nutrient for human health and is a critical ingredient in ONS. Helping to educate patients on the value of “added sugars” in ONS may be useful to improve compliance with nutritional recommendations when ONS are indicated. This perspective paper reviews the important roles of “added sugars” in ONS, in terms of flavor, function, and product formulation.

A Pilot Study of the Snap & Sniff Threshold Test

OBJECTIVES

The Snap & Sniff^® Threshold Test (S&S) has been recently developed to determine the olfactory threshold. The aim of this study was to further evaluate the validity and test-retest reliability of the S&S.

METHODS

The olfactory thresholds of 120 participants were determined using both the Smell Threshold Test (STT) and the S&S. The participants included 30 normosmic volunteers and 90 patients (60 hyposmic, 30 anosmic). The normosmic participants were retested using the STT and S&S at an intertest interval of at least 1 day.

RESULTS

The mean olfactory threshold determined with the S&S was -6.76 for the normosmic participants, -3.79 for the hyposmic patients, and -2 for the anosmic patients. The olfactory thresholds were significantly different across the 3 groups ( P < .001). Snap & Sniff-based and STT-based olfactory thresholds were correlated weakly in the normosmic group (correlation coefficient = 0.162, P = .391) but more strongly correlated in the patient groups (hyposmic: correlation coefficient = 0.376, P = .003; anosmic: correlation coefficient = 1.0). The test-retest correlation for the S&S-based olfactory thresholds was 0.384 ( P = .036).

CONCLUSION

Based on validity and test-retest reliability, we concluded that the S&S is a proper test for olfactory thresholds.

Association of alterations in smell and taste with depression in older adults

Objective

Examine the relationship between depression and changes in smell or taste.

Study Design

Cross‐sectional analysis of 2011–2012 and 2013–2014 National Health and Nutrition Examination Survey (NHANES).

Methods

We examined 5,275 adults ≥40 years old who completed smell and taste questionnaires as well as a validated depression assessment instrument, the Patient Health Questionnaire (PHQ‐9). Analyses incorporated sampling weights to account for the complex sampling design and associations were analyzed using multivariate logistic regression adjusted for related demographics and socioeconomic data.

Results

The prevalence of altered smell and taste was 23.0% (95% CI: 20.7–25.3%) and 11.9% (95% CI: 10.7–13.1%), respectively. Among those who met criteria for major depressive disorder, the prevalence of altered smell and taste was higher at 39.8% (95% CI: 33.4–46.1%) and 23.7% (95% CI: 18.7–28.7%), respectively. In a multivariate model adjusting for age, gender, education, major comorbidities, smoking history, heavy alcohol use, sinus disease, cold symptoms, and trauma history, adults ≥40 and <65 years old who reported alterations in smell (OR: 1.64, p = 0.004) and adults ≥40 years old who reported alterations in taste (OR: 1.77, p = 0.001) were more likely to meet criteria for major depressive disorder.

Conclusion

There is a strong association between major depression and alterations in smell and taste among certain age groups in the general U.S. population. Primary care providers should screen for depression when patients report changes in smell or taste.

Level of Evidence

4.

Olfactory epithelium: Cells, clinical disorders, and insights from an adult stem cell niche

Disorders causing a loss of the sense of smell remain a therapeutic challenge. Basic research has, however, greatly expanded our knowledge of the organization and function of the olfactory system. This review describes advances in our understanding of the cellular components of the peripheral olfactory system, specifically the olfactory epithelium in the nose. The article discusses recent findings regarding the mechanisms involved in regeneration and cellular renewal from basal stem cells in the adult olfactory epithelium, considering the strategies involved in embryonic olfactory development and insights from research on other stem cell niches. In the context of clinical conditions causing anosmia, the current view of adult olfactory neurogenesis, tissue homeostasis, and failures in these processes is considered, along with current and future treatment strategies.

Level of Evidence

NA.

Significance of imaging in the diagnosis of olfactory disorder

The aim of this retrospective analysis was to examine olfactory disorders among the patients in the Ear, Nose, and Throat Clinic of Tampere University Hospital, Finland, from 2001 to 2011, and to evaluate the necessity of imaging in the examination of patients with olfactory disorders. Charts of 143 consecutive patients with a primary olfactory disorder were examined, and 69 patients who had undergone the necessary testing were included in the study. The most common causes of olfactory disorder were upper respiratory infection (23%), chronic rhinosinusitis (19%), head trauma (17%), and allergic or nonallergic rhinitis (6%). In 25% of the patients, no obvious cause for the symptoms was found. Computed tomography (CT) scans were normal in 37 of 52 (71%) patients and magnetic resonance imaging was normal in 21 of 25 (84%) patients. No intracranial or intranasal tumors were found in the overall cohort. Of the patients with additional symptoms (facial pain, headache, nasal discharge, or stuffiness), 58% had chronic rhinosinusitis. Of the patients with no additional symptoms or signs associated with chronic rhinosinusitis on clinical evaluation, only 2% had chronic rhinosinusitis on imaging. Only the detection of chronic rhinosinusitis and head trauma had clinical value in the determination of the etiology. A sinonasal CT scan should be considered in patients who have at least one symptom associated with sinusitis in addition to an olfactory disorder to confirm the etiology and to find those patients who may benefit from medical therapy or surgical treatment.

Characterization and Correction of Olfactory Deficits in Kidney Disease

Patients with CKD suffer from food aversion, anorexia, and malnutrition. Although olfaction has a significant role in determining food flavor, our understanding of olfactory impairment and of the olfaction-nutrition axis in patients with kidney disease is limited. We quantified odor identification, odor threshold, and subjective odor perception in a cohort (n=161) comprising 36 participants with CKD, 100 participants with ESRD, and 25 controls. We investigated olfaction-nutrition associations in these participants and examined a novel intervention to improve olfaction in ESRD. The mean odor identification score was lower in patients with CKD (75.6%±13.1%; P=0.02) and ESRD (66.8%±15.1%; P<0.001) than in controls (83.6%±11.4%). Patients with ESRD exhibited higher odor threshold than the remaining participants exhibited. All groups had similar scores for subjective smell assessment. In multivariable adjusted analyses, kidney disease associated with increased odds of odor identification deficits (odds ratio, 4.80; 95% confidence interval, 1.94 to 11.89). A reduction in odor identification score was associated with higher subjective global assessment score and lower serum total cholesterol, LDL cholesterol, and albumin concentrations. We found no associations between odor threshold and nutritional parameters. In a proof of concept, 6-week, open-label clinical trial, intranasal theophylline (an epithelial membrane transport and proton secretion activator) increased odor identification score in five out of seven (71%) patients with ESRD. In conclusion, patients with kidney disease have olfactory deficits that may influence their nutritional status. Our preliminary results regarding olfactory improvement using intranasal theophylline warrant confirmation in a randomized controlled trial.

Adaptive and maladaptive neural compensatory consequences of sensory deprivation-From a phantom percept perspective

It is suggested that the brain undergoes plastic changes in order to adapt to changing environmental needs. Sensory deprivation results in decreased input to the brain leading to adaptive or maladaptive changes. Although several theories hypothesize the mechanism of these adaptive and maladaptive changes, the course of action taken by the brain heavily depends on the age of incidence of damage. The growing body of literature on the topic proposes that maladaptive changes in the brain are instrumental in creating phantom percepts, defined as the perception of a sensory experience in the absence of a physical stimulus. The current article reviews the mechanisms of adaptive and maladaptive plasticity in the brain in congenital, early, and late-onset sensory deprivation in conjunction with the phantom percepts in the different sensory domains. We propose that the mechanisms of adaptive and maladaptive plasticity fall under a universal construct of updating hierarchical Bayesian prediction errors. This theory of the Bayesian brain hypothesizes that the brain constantly compares its internal milieu with changing environmental cues and either adjusts its predictions or discards the change, depending on the novelty or salience of the external stimulus. We propose that adaptive plasticity reflects both successful bottom-up compensation and top-down updating of the model while maladaptive plasticity reflects failure in one or both mechanisms, resulting in a constant prediction-error. Finally, we hypothesize that phantom percepts are generated by the brain as a solution to this prediction error and are thus a manifestation of unsuccessful adaptation to sensory deprivation.

A systematic review of smell alterations after radiotherapy for head and neck cancer

PURPOSE

To review the current knowledge on radiotherapy associated olfactory dysfunction among head and neck cancer (HNC) patients.

METHODS

A systematic review of RT-related olfactory dysfunction in HNC was performed. Searches were conducted in several databases (Medline, EMBASE, CINAHL, CAB Abstracts, SCOPUS, Proquest Dissertations and Theses, PROSPERO, ALLEBM Reviews - Cochrane DSR, ACP Journal Club, DARE, CCTR, CMR, HTA, and NHSEED). Publications investigating olfactory dysfunction as an explicit side effect of Radiotherapy (RT, or RT-chemo or RT-monoclonal antibodies) were eligible, no limits were applied.

RESULTS

Two hundred and twenty-nine papers were screened and 23 met inclusion criteria.

CONCLUSIONS

Odor detection, identification and discrimination are olfactory functions impaired after RT for HNC. An RT dose-effect has been calculated for odor identification and odor discrimination. There were no studies of the effect of olfactory dysfunction on weight loss or energy intake among RT-treated HNC patients. To improve our understanding of RT associated olfactory dysfunction among HNC patients, future studies should include a multi-dimensional assessment of olfactory function in a longitudinal design, track other conditions affecting olfaction, assess retronasal olfactory perception, adopt validated self-report tools and explore the impact of olfactory dysfunction on the eating experience of HNC patients.

Posttraumatic olfactory dysfunction

Impairment of smell may occur following injury to any portion of the olfactory tract, from nasal cavity to brain. A thorough understanding of the anatomy and pathophysiology combined with comprehensively obtained history, physical exam, olfactory testing, and neuroimaging may help to identify the mechanism of dysfunction and suggest possible treatments. Although most olfactory deficits are neuronal mediated and therefore currently unable to be corrected, promising technology may provide novel treatment options for those most affected. Until that day, patient counseling with compensatory strategies and reassurance is essential for the maintenance of safety and QoL in this unique and challenging patient population.

Higher Body Mass Index Is Associated with Subjective Olfactory Dysfunction

BACKGROUND

Morbidly obese patients demonstrate altered olfactory acuity. There has been no study directly assessing Body Mass Index (BMI) in patients with olfactory dysfunction. Our purpose was to compare BMI in a group of patients with subjective olfactory dysfunction to those without subjective olfactory complaints.

METHODS

Retrospective matched case-control study. Sixty patients who presented to a tertiary care otolaryngology center with subjective smell dysfunction over one year were identified. Neoplastic and obstructive etiologies were excluded. Demographics, BMI, and smoking status were reviewed. Sixty age, gender, and race matched control patients were selected for comparison. Chi-square testing was used.

RESULTS

48 out of 60 patients (80%) in the olfactory dysfunction group fell into the overweight or obese categories, compared to 36 out of 60 patients (60%) in the control group. There was a statistically significant difference between the olfactory dysfunction and control groups for this stratified BMI (p = 0.0168).  

CONCLUSION

This study suggests high BMI is associated with olfactory dysfunction. Prospective clinical research should examine this further to determine if increasing BMI may be a risk factor in olfactory loss and to elucidate what role olfactory loss may play in diet and feeding habits of obese patients.

A Pilot Study of the Self-Administered Computerized Olfactory Testing System

Background

The Self-Administered Computerized Olfactory Testing System (SCOTS) was developed recently to perform the olfactory threshold test under computer control. The aim of this study was to evaluate the validity and test-retest reliability of the SCOTS.

Methodology

A total of 180 subjects were tested for olfactory thresholds using an odor detection threshold test and the SCOTS. There were 60 normosmic volunteers, 60 hyposmic patients, and 60 anosmic patients. Among them, 30 normosmic subjects were retested with the SCOTS at least 1 day after the first test occasion. The olfactory threshold test and retest results from the SCOTS were compared.

Results

The mean olfactory threshold attained from the SCOTS was -5.48 for normosmic subjects, -3.18 for hyposmic patients, and -2 for anosmic patients. The olfactory thresholds among the normosmic, hyposmic, and anosmic patients were significantly different (p < .001). The correlation coefficient between the olfactory thresholds of an odor detection threshold test and the SCOTS was 0.809 (p < .001). The test-retest correlation for the SCOTS-based olfactory thresholds was strong (r = 0.671; p < .001).

Conclusion

Our results show that on the basis of its validity and test-retest reliability, the SCOTS was appropriate for self-administered tests of the olfactory threshold.

Main causes and diagnostic evaluation in patients with primary complaint of olfactory disturbances

Introduction

Establishing a diagnosis in patients with olfactory disturbances has always been challenging for physicians.One reason for this is the rarity of some of the diseases that affect this sense, such as Kallmann's syndrome and post-viral olfactory loss.

Objective

To identify the major causes of olfactory disturbances and to describe the diagnostic evaluation in outpatients attended to at an ambulatory clinic specialized in olfaction disorders.

Methods

A retrospective analysis was performed in outpatients with primary olfactory complaint attended to between June 1, 2011 and September 30, 2013 in a center specialized in olfactory disorders. Patient history, nasofibroscopy, and the University of Pennsylvania Smell Identification Test (UPSIT) comprised the examination.

Results

Sixty-two patients were evaluated. The major causes were chronic rhinosinusitis (31%); rhinitis, primarily the allergic type (19%); post-viral olfactory loss (13%); and post-traumatic loss (8%). UPSIT scores were statistically different among different etiologies (p = 0.01).

Conclusions

The major diagnoses that should be part of the physician assessment when a patient complains of olfactory disturbance are chronic rhinosinusitis with and without polyps, allergic rhinitis, post-viral olfactory loss, and post-traumatic loss.