Underestimated olfactory domains in Huntington's disease: odour discrimination and threshold

BACKGROUND

Olfaction has recently found clinical value in prediction, discrimination and prognosis of some neurodegenerative disorders. However, data originating from standard tests on olfactory dysfunction in Huntington's disease are limited to odour identification, which is only one domain of olfactory perceptual space.

METHOD

Twenty-five patients and 25 age- and gender-matched controls were evaluated by the Sniffin' Sticks test in three domains of odour threshold, odour discrimination, odour identification and the sum score of them. Patients' motor function was assessed based on the Unified Huntington's Disease Rating Scale.

RESULTS

Compared with controls, patients' scores of all olfactory domains and their sum were significantly lower. Besides, our patients' odour threshold and odour discrimination impairments were more frequently impaired than odour identification impairment (86 per cent and 81 per cent vs 34 per cent, respectively).

CONCLUSION

Olfactory impairment is a common finding in patients with Huntington's disease; it is not limited to odour identification but is more pronounced in odour discrimination and odour threshold.

Olfaction-associated quality of life: Polish adaptation and validation of a Questionnaire of Olfactory Disorders (QOD-PL) in patients with chronic rhinosinusitis

BACKGROUND

The focus on health-related quality of life (HRQOL) in medical research is becoming more and more intensive, with attention being paid to the patient's subjective feelings and assessment of one's health status. Smell disorders can significantly impact human life. The Questionnaire of Olfactory Disorders (QOD) is a self-monitoring questionnaire that provides subjective information about olfactory disorders.

OBJECTIVES

This study aimed to check the reliability and validation of the Polish version of QOD (QOD-PL) for use in patients with olfactory impairment in Poland.

MATERIAL AND METHODS

A total of 158 patients (76 females, mean age (Mage) 45.97 ±16.37 years), suffering from chronic rhinosinusitis (CRS), whose olfactory function was measured using the Sniffin' Sticks test (SST), were studied. All patients completed 3 validated questionnaires: Importance of Olfaction (IO), Sino-Nasal Outcome Test-22 (SNOT-22) and QOD-PL.

RESULTS

Internal consistency and test-retest reliability of the entire QOD-PL scale were good (Cronbach's α = 0.88). The convergent validity of the QOD-PL and its subscales correlated with IO and SNOT-22. The life quality statements in the QOD-PL (QOD-PL-LQ) score, its negative statements, and the mean score for VAS scales were significantly and positively correlated with all symptoms measured with SNOT-22 and none of the IO scales.

CONCLUSIONS

The QOD-PL is a reliable, valid and important tool for assessing HRQOL in patients with olfactory disorders. However, it is important to note that not all of its subscales can be considered and interpreted separately.

Olfactory and taste disorders in COVID-19: a cross-sectional study in primary health care

OBJECTIVE

The objective of this study was to describe the occurrence of self-reported olfactory and taste disorders in non-hospitalized Brazilian adults who presented severe acute respiratory syndrome-related coronavirus 2 infection symptoms and attended primary health care.

METHODS

This cross-sectional study was based on a routine standardized diagnostic screening questionnaire applied in a Brazilian primary care facility. The olfactory and taste disorder occurrence was compared between severe acute respiratory syndrome-related coronavirus 2-positive and severe acute respiratory syndrome-related coronavirus 2-negative cases and described by age and sex.

RESULTS

Severe acute respiratory syndrome-related coronavirus 2-positive patients had a higher proportion of self-reported olfactory and taste disorders, as compared with severe acute respiratory syndrome-negative (50.7%, vs. 20.6%, p<0.0001). Of all individuals with self-reported olfactory and taste disorder cases, 69% presented both olfactory and taste impairments, 13% olfactory only, and 17% taste only. In severe acute respiratory syndrome-related coronavirus 2-positive cases, the frequency of olfactory and taste disorders was significantly higher among females as compared with males (71% vs. 34%). Additionally, people with olfactory and taste disorders were significantly younger in the severe acute respiratory syndrome-related coronavirus 2-positive group.

CONCLUSION

Self-reported olfactory and taste disorders are highly common among non-hospitalized severe acute respiratory syndrome-related coronavirus 2-positive Brazilian people who attended the Family Health Care Unit. The co-occurrence of both self-reported olfactory and taste disorders was more frequent than self-reported olfactory or taste disorders alone.

Cross-cultural modification of the University of Pennsylvania smell identification test for the Saudi Arabian population: Validation and normative values

OBJECTIVES

To develop a reliable version of the Saudi Arabian-University of Pennsylvania smell identification test (SA-UPSIT) and to establish normative values for both genders.

METHODS

This cross-sectional study was carried out on voluntarily recruited normal participants in King Saud University Medical City, Riyadh, Saudi Arabia, from April 2018 to May 2023. Culture-familiar odors were chosen and the kit was translated into Arabic for the study. The test was modified 3 times in 4 versions. Following this, a random sample was collected to carry out a re-test after 6 weeks.

RESULTS

A total of 288 subjects participated in the development of the SA-UPSIT across all versions, including 146 females and 142 males. The average age of the participants was 28.4±9.9 years. In the final version, 111 participants scored an average of 34.5±2.5 for the total score, 35±2.3 for females, and 34.1±2.6 for males. The test-retest reliability coefficient was 0.73, indicating acceptable reliability.

CONCLUSION

The new changes carried out to the SA-UPSIT increased the average scores and demonstrated good reliability, making it clinically applicable for diagnosing and monitoring olfactory dysfunction.

Threshold and suprathreshold component analysis in olfactory dysfunction: a retrospective study

OBJECTIVE

To analyse variations in the n-butanol threshold and odour identification scores of the Connecticut Chemosensory Clinical Research Centre test in various grades of olfactory dysfunction and in different nasal conditions leading to olfactory loss.

METHOD

Retrospective observational study.

RESULTS

All grades of olfactory dysfunction were predominantly noted among males. In chronic rhinosinusitis, anosmia or severe hyposmia was seen in 87.5 per cent of patients without polyps in comparison with 68 per cent of patients with polyps. In addition, 90 per cent of patients with atrophic rhinitis and post-traumatic loss had anosmia, but only 30.7 per cent of patients with allergic rhinitis had anosmia. Pepper was the most affected smell for all the nasal diseases except atrophic rhinitis, in which asafoetida and baby powder smells were affected more.

CONCLUSION

In most inflammatory sinonasal conditions, odour identification is relatively preserved even when the threshold is maximally affected. In patients with comparable olfactory dysfunction based on the Connecticut Chemosensory Clinical Research Centre test score, a relatively preserved suprathreshold odour identification score may predict better prognosis.

Incidence of Olfactory Dysfunction and Associated Factors: A Nationwide Cohort Study From South Korea

OBJECTIVES

Olfactory dysfunction, a reduced or complete loss of the ability to smell, is gaining attention because of its substantial impact on an individual's quality of life and the possibility that it is an important sign of underlying disease. However, olfactory dysfunction is underdiagnosed in the general population due to diagnostic difficulty and unpredictable prognosis. This study aimed to evaluate the prevalence of clinically diagnosed olfactory dysfunction in South Korea by using well-organized, nationwide, population-based cohort data, and the associations between olfactory dysfunction and risk of neurodegenerative disorders.

METHODS

We investigated the Korean National Health Insurance Service-National Sample Cohort for patients diagnosed with olfactory dysfunction according to the International Classification of Diseases. Annual and overall incidence and prevalence of olfactory dysfunction during 2003 to 2013 and patient characteristics were analyzed. Based on those identified patients who were later diagnosed with neurodegenerative disorder, hazard ratios (HRs) of sociodemographic factors and comorbidities associated with neurodegenerative disorder were evaluated using a Cox proportional hazard regression model.

RESULTS

In total, 6296 patients were clinically diagnosed with olfactory dysfunction during the study period (524.67 patients/year). The prevalence increased annually and was higher in female patients. The incidence of neurodegenerative disorders among patients with olfactory dysfunction was 4.2% within the study period. Multivariate cox regression analysis of the patients (n = 249) revealed that diabetes mellitus (HR = 1.976) and depression (HR = 2.758) were significant risk factors.

CONCLUSIONS

Olfactory dysfunction is underdiagnosed in South Korea, but it is clinically important considering the possibility of presymptom of neurodegenerative disorders. In clinical practice, we should consider its association with neurodegenerative disorders and possibly other systemic conditions.

Chemosensory Dysfunction 3-Months After COVID-19, Medications and Factors Associated with Complete Recovery

OBJECTIVES

To examine the longitudinal prevalence and recovery of olfactory, gustatory, and oral chemesthetic deficits in a sizable cohort of SARS-CoV-2 infected persons using quantitative testing. To determine whether demographic and clinical factors, mainly the medications used after the COVID-19 diagnosis, influence the test measures.

METHODS

Prospective cohort in a hospital with primary, secondary, tertiary, and quaternary care. Patients with confirmed COVID-19 were tested during the acute infection phase (within 15 days of initial symptom, n = 187) and one (n = 113) and 3 months later (n = 73). The University of Pennsylvania Smell Identification Test, the Global Gustatory Test, and a novel test for chemesthesis were administered at all visits.

RESULTS

During the acute phase, 93% were anosmic or microsmic and 29.4% were hypogeusic. No one was ageusic. A deficit in oral chemesthesis was present in 13.4%. By 3 months, taste and chemesthesis had largely recovered, however, some degree of olfactory dysfunction remained in 54.8%. Remarkably, patients who had been treated with anticoagulants tended to have more olfactory improvement. Recovery was greater in men than in women, but was unrelated to disease severity, smoking behavior, or the use of various medications prior to, or during, COVID-19 infection.

CONCLUSIONS

When using quantitative testing, olfactory disturbances were found in nearly all SARS-CoV-2 infected patients during the acute infection phase. Taste or chemesthetic deficits were low. Olfactory impairment persisted to some degree in over half of the patients at the 3-month follow-up evaluation, being more common in women and less common in those who had been treated earlier with anticoagulants.

LEVEL OF EVIDENCE

3.

Relationship of Lesion Location to Postoperative Steroid Use in Eosinophilic Chronic Rhinosinusitis

OBJECTIVES

Eosinophilic chronic rhinosinusitis (ECRS) is known to recur after surgery. The treatment choice for recurrent ECRS, such as oral steroids or biological agents, must be chosen carefully, and identifying the lesion location may be useful. This study aimed to evaluate the postoperative course of ECRS patients and assess the relationship between endoscopic lesion location and postoperative oral steroid use.

METHODS

Patients with chronic rhinosinusitis who underwent bilateral endoscopic sinus surgery from April 2018 to March 2020 were divided into two groups based on the presence or absence of oral steroid use after surgery. The primary endpoint was the lesion location on endoscopic findings during surgery: middle turbinate, middle meatus, superior turbinate, superior meatus, nasal septum, and sphenoethmoidal recess. Subjective symptoms, blood tests, and computerized tomography (CT) findings (Lund-Mackay score) were evaluated as secondary endpoints.

RESULTS

Among 264 patients, 88 were diagnosed histologically with ECRS (mean 48.98 ± 1.40 years, 67 males/21 females). Twenty-three patients were steroid-using, 65 were steroid-free, and six stopped attending their appointments. Patients with sphenoethmoidal recess lesions were significantly more likely to require steroids (p = 0.019). There was a significant association between steroid use and younger age (p = 0.041), olfactory dysfunction (p = 0.021), and all sinuses (Frontal sinus: p < 0.001, Anterior ethmoid sinus: p = 0.002, Posterior ethmoid sinus: p = 0.011, Maxillary sinus: p = 0.018, Sphenoid sinus: p = 0.034, Total score: p < 0.001).

CONCLUSION

A sphenoethmoidal recess lesion was a risk factor for requiring postoperative steroids. Young age, olfactory dysfunction, and preoperative severe CT findings were also significant risk factors.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:2511-2516, 2023.

Partial Reversal of Anosmia Following Platinum-Based Chemotherapy in a Patient With Colorectal Adenocarcinoma

Platinum-based chemotherapy is known to cause taste and smell changes (TSCs) via a host of mechanisms, including altered receptor activity, saliva/mucus production, and induction of receptor destruction via mitotic inhibition. In the literature to date, these changes have primarily resulted in worsening of taste and smell. In this case report, we document the first instance of an individual regaining their sense of olfactory detection following treatment with oxaliplatin for colorectal adenocarcinoma. We theorize that the improvement in his sense of smell may have resulted from oxaliplatin-induced destruction of his nasal polyps through the caspase-9/procaspase-9 apoptotic pathway, a pathway shared with other mechanisms of nasal polyp destruction. These findings were supported by nasal endoscopy and sphenoid sinusoscopy, which demonstrated no clinical persistence of nasal polyps, in contrast to nasal endoscopy prior to chemotherapy which demonstrated persistent nasal polyposis. Objective smell testing post-treatment revealed a diminished ability to discriminate odors. Chemotherapy-induced TSCs play a key role in poor weight gain, food aversion, emotional distress, and an overall decrease in quality of life, and patients should be informed of these potential consequences prior to starting treatment. However, in patients with anosmia secondary to nasal polyposis, treatment with platinum-based chemotherapy may provide an additional therapeutic benefit. Further studies may help elucidate the potential therapeutic benefits of these agents in managing steroid-resistant polyposis for patients suffering from olfactory dysfunction.

Hyposmia in COVID-19: Temporal Recovery of Smell: A Preliminary Study

Background and Objectives: Hypo/anosmia is a characteristic symptom of COVID-19 infection. The aim of this study is to investigate the time of smell recovery and to identify a possible order of perception recovery of different odors in COVID-19 patients. Materials and Methods: A prospective observational study was conducted on not hospitalized COVID-19 patients, selected according to eligible criteria. The study was approved by the Ethical Committee. A questionnaire formulated by our team was submitted to patients in order to know the duration of the hypo/anosmia and hypo/ageusia and the order of odor recovery: vanillin (mixed olfactory/gustatory substances), phenyl ethyl alcohol (rosewater) (pure olfactory substances), eucalyptol (mixed olfactory/trigeminal substances), and eugenol (mixed olfactory/trigeminal/gustatory substances). Results: 181 patients were included. Hypo/ageusia and hypo/anosmia lasted on average 10.25 (±8.26) and 12.8 (±8.80) days, respectively. The most frequent odor recovery sequence was: (1) phenyl ethyl alcohol; (2) eucalyptol; (3) vanillin; and (4) eugenol. In COVID-19 patients, hypo/anosmia occurs more often in women and at a young age. Conclusions: This preliminary investigation highlighted novel data: there is a chronological order in perception recovery of different olfactory substances and, therefore, in the restoration of the various sensitive nerve pathways involved in the sense of smell.

Subjective Perception of Recovery and Measured Olfactory Function in COVID-19 Patients

This cross-sectional study aimed to investigate self-rated olfactory dysfunction in relation to measured olfactory function after partial or complete subjective recovery in individuals with a history of coronavirus disease 2019 (COVID-19) infection. A total of 186 individuals (aged 5-62 years) with a history of COVID-19 infection were included. Visual analogue scale (VAS) ratings for olfactory function (before, during, and after infection) and age-appropriate psychophysical olfactory test scores (odor threshold and odor identification: "Sniffin' Sticks" for adults and both "Sniffin' Sticks" and "U-Sniff" for children) were determined. Participants were assigned to four "age groups" and three "recovery classes" (incomplete recovery, complete recovery, no smell loss). Surprisingly, there were no significant differences in odor threshold and adult identification scores between the "recovery classes". However, children with "incomplete recovery" had lower identification scores than those with "complete recovery" (p = 0.033) and those with "no smell loss" (p = 0.022). The pediatric age groups had significantly higher VAS ratings during and after COVID-19 compared to older participants. Older individuals experienced greater magnitude of changes in their sense of smell after COVID-19 infection, but those with parosmia were 3.5 times more likely to report "incomplete recovery" of olfaction after COVID-19. The general prognosis for olfactory recovery after COVID-19 is good but appears to be particularly confounded by the presence of parosmia, leading patients to subjectively report incomplete olfactory recovery. Although it is of high significance to monitor recovery using validated psychophysical olfactory tests, subjective measures of olfaction help provide specific insight, especially for qualitative olfactory dysfunction.

Italian version of the brief Questionnaire of Olfactory Disorders (brief-IT-QOD)

Objective

To evaluate the reliability and validity of the Italian brief-QOD (Brief-IT-QOD).

Methods

The study consisted of six phases: item generation, reliability analysis (112 dysosmic patients for internal consistency analysis and 61 for test-retest reliability analysis), normative data generation (303 normosmic subjects), validity analysis (comparison of Brief-IT-QOD scores of healthy and dysosmic subjects and scores correlation with psychophysical olfactory testing (TDI) and SNOT-22 scores), responsiveness analysis (10 dysosmic chronic rhinosinusitis with nasal polyps (CRSwNP) patients before and after biologic therapy), and cut-off value determination (ROC curve analysis of Brief-IT-QOD sensitivity and specificity).

Results

All subjects completed the Brief-IT-QOD. Internal consistency (α > 0.70) and test-retest reliability (ICC > 0.7) were acceptable and satisfactory for both questionnaire subscales. A significant difference between dysosmic and control subjects was found in both subscales (p < 0.05). Significant correlations between subscales scores and TDI and SNOT-22 scores were observed. Brief-IT-QOD scores before treatment were significantly higher than after biological therapy.

Conclusions

Brief-IT-QOD is reliable, valid, responsive to changes in QoL, and recommended for clinical practice and outcome research.

Depression Severity Is Different in Dysosmic Patients Who Have Experienced Traumatic Brain Injury Compared with Those Who Have Not

Traumatic brain injury (TBI) in humans can result in olfactory, cognitive, and affective changes. Surprisingly, research on the consequences of TBI often did not control for olfactory function in the investigated groups. Consequently, the affective or cognitive differences might be misleading as related rather to different olfactory performance than to a TBI experience. Hence, our study aimed to investigate whether TBI occurrence would lead to altered affective and cognitive functioning in two groups of dysosmic patients, one with TBI experience and one without. In total, 51 patients with TBI experience and 50 controls with varied causes of olfactory loss were thoroughly examined in terms of olfactory, cognitive, and affective performance. Student t-tests demonstrated that the only significant difference between the groups appeared in the depression severity, with TBI patients being more depressed (t = 2.3, p = 0.011, Cohen's d = -0.47). Regression analyses further showed that TBI experience was significantly associated with depression severity (R2 = 0.05, F [1, 96] = 5.5, p = 0.021, beta = 1.4). In conclusion, the present study showed that TBI experience is linked to depression, which is more pronounced compared to individuals with olfactory loss without TBI.

Persistent olfactory dysfunction associated with poor sleep quality and anxiety in patients with long COVID

Introduction

Poor sleep quality have been widely reported in patients with long COVID. Determining the characteristics, type, severity, and relationship of long COVID with other neurological symptoms is essential for the prognosis and management of poor sleep quality.

Methods

This cross-sectional study was conducted at a public university in the eastern Amazon region of Brazil between November 2020 and October 2022. The study involved 288 patients with long COVID with self-report neurological symptoms. One hundred thirty-one patients were evaluated by using standardised protocols: Pittsburgh sleep quality index (PSQI), Beck Anxiety Inventory, Chemosensory Clinical Research Center (CCRC), and Montreal Cognitive Assessment (MoCA). This study aimed to describe the sociodemographic and clinical characteristics of patients with long COVID with poor sleep quality and their relationship with other neurological symptoms (anxiety, cognitive impairment, and olfactory disorder).

Results

Patients with poor sleep quality were mainly women (76.3%), 44.04 ± 12.73 years old, with >12 years of education (93.1%), and had monthly incomes of up to US $240.00 (54.2%). Anxiety and olfactory disorder were more common in patients with poor sleep quality.

Discussion

Multivariate analysis shows that the prevalence of poor sleep quality was higher in patients with anxiety, and olfactory disorder is associated with poor sleep quality. In this cohort of patients with long COVID, the prevalence of poor sleep quality was highest in the group tested by PSQI and were associated with other neurological symptoms, such as anxiety and olfactory dysfunction. A previous study indicates a significant association between poor sleep quality and psychological disorders over time. Recent studies involving neuroimaging found functional and structural changes in Long COVID patients with persistent olfactory disfunction. Poor sleep quality are integral part of complex changes related to Long COVID and should be part of patient's clinical management.

High prevalence of olfactory dysfunction detected in treatment-naive patients with head and neck cancer

BACKGROUND

Previous studies demonstrated the difficulty of patients with Head and Neck Cancer (HNC) in sensing food taste, a function in which olfaction has a significant role. However, neither study employed psychophysical tests or control groups to establish the veracity of such complaints.

AIMS/OBJECTIVES

In this study, we quantitatively tested the olfactory function of HNC individuals and compared their function to that of healthy controls.

METHODS

Thirty-one HNC naïve treatment patients and thirty-one controls, matched for sex, age, schooling, and smoking, were tested with the University of Pennsylvania Smell Identification Test (UPSIT).

RESULTS

The olfactory function was significantly worse among the patients diagnosed with head and neck cancer [UPSIT cancer = 22.9(CI 95%: 20.5-25.4) vs. UPSIT controls = 29.1(CI 95%: 26.9-31.3); p < .001]. Most patients with HNC had olfactory disorders (n = 29, 93.5%). The risk of olfactory loss was higher in the cancer group [OR: 10.5(CI 95%: 2.1-51.9; p = .001)].

CONCLUSION AND SIGNIFICANCE

Olfactory disorders can be detected in more than 90% of patients with head and neck cancer when evaluated using a well-validated olfactory test. Smell disorders may be a potential marker for early diagnosis of HNC.

Applicability of Sniffin' Sticks Identification Test as a Screening Tool for Olfactory Dysfunction in Northeast China

BACKGROUND Because most case of smell loss are unrecognized, a valid and reliable screening test for olfactory function is needed. The Sniffin' Sticks test is one of the most widely used olfactory tests. As olfaction can be affected by environment and social background, we investigated the regional applicability of Sniffin' Sticks identification subtest as a screening tool. MATERIAL AND METHODS Normosmic volunteers were recruited between May 2021 and August 2021. We collected data on participants' age, sex, and educational level. The Self-Reported Mini-Olfactory Questionnaire and identification test of Sniffin' Sticks test battery were used to assess their olfactory function. RESULTS A total of 688 subjects (316 male, 371 female) volunteered for the screening test. The mean age of participants was 30±7.69 years (range, 15-63 years), and the average score of all subjects was 12.7±0.81 points. The 3 least recognized items among all 16 tests were lemon (correct identification rate 5.4%), clove (correct identification rate 1.5%), and apple (correct identification rate 0.7%). For Self-Reported Mini-Olfactory Questionnaire, 48 of the 687 subjects (7%) stated that they could not recognize the smell of freshly mowed grass. CONCLUSIONS We investigated the applicability of using Sniffin' Sticks Identification test and Self-MOQ as a screening tool for olfactory dysfunction in northeast China. Most of the subjects enrolled in this study failed to reach the normative standard for their age groups in the Sniffin' Sticks test. We suggest the deletion or replacement of items with extremely low correct identification rates and that physicians who use the Sniffin's Sticks test in clinical practice test the applicability in advance to avoid misdiagnosis.

Dysphagia, dysphonia and olfactory disease: a map of Cochrane evidence relevant to rehabilitation for people with post COVID-19 condition

INTRODUCTION

Currently, no evidence exists on specific treatments for post COVID-19 condition (PCC). However, rehabilitation interventions that proved effective for similar symptoms in other health conditions could be applied to people with PCC. With this overview of systematic reviews with mapping, we aimed to describe the Cochrane evidence on rehabilitation interventions proposed for dysphagia, dysphonia and olfactory dysfunction in different health conditions that can be relevant for PCC.

EVIDENCE ACQUISITION

We searched the last five years' Cochrane Systematic Review (CSRs) using the terms "dysphagia," "swallowing disorder," "dysphonia," "voice disorder," "olfactory dysfunction," "smell changes" and "rehabilitation" in the Cochrane Library. We extracted and summarized the available evidence using a map. We grouped the included CSRs for health conditions and interventions, indicating the effect and the quality of evidence.

EVIDENCE SYNTHESIS

We found 170 CSRs published between 2016 and 2021 and 1 was included. It provided data on dysphagia in acute and subacute stroke. Interventions included were acupuncture, neuromuscular electrical stimulation, transcranial magnetic stimulation and behavioral interventions, and swallowing therapy, with very low- to moderate-quality evidence. We did not find any CSR on dysphonia and olfactory disease.

CONCLUSIONS

These results are the first step of indirect evidence able to generate helpful hypotheses for clinical practice and future research. They served as the basis for the three recommendations on treatments for these PCC symptoms published in the current WHO Guidelines for clinical practice.

Phantosmia May Predict Long-Term Measurable Olfactory Dysfunction After COVID-19

Objectives

Persistent olfactory dysfunction (OD) after 6 months caused by SARS‐CoV‐2 infection has been reported with a variable prevalence worldwide. This study aimed to determine the prevalence of long‐term OD and identify predisposing factors.

Methods

A prospective cohort study was conducted on 100 adults with COVID‐19. Olfactory function was assessed with the University of Pennsylvania Smell Identification Test and a symptom survey at the onset of disease and 30 days later. Patients with persistent quantitative OD at the second assessment were reevaluated after 1 year. Demographic variables, symptoms, and the degree of smell loss were analyzed.

Results

Participants included 100 patients. The mean age was 42.2 ± 15.6 years, 55 (55%) were female, and 56 (56%) were outpatients. Baseline smell loss was identified in 75/100 (75%) patients, decreasing to 39/95 (40%) after 1 month, and persisting in 29 patients after 1 year. Phantosmia at baseline was the only risk factor identified for persistent OD after 1 year (relative risk 2.51; 95% confidence interval 1.53–4.12; p < 0.001). Regardless of the outcome in smell function, a significant decline in olfaction was associated with the presence of phantosmia at 1 month (β = −12.39; 95% CI −19.82 to −4.95; p < 0.01).

Conclusions

SARS‐CoV‐2 (2019–2020 variants) produced a highly frequent OD that persisted in 29% of the patients after 1 year. The presence of phantosmia at baseline and 1 month was associated with a worse evolution, but phantosmia may interfere with the performance in an identification smell test. A longer follow‐up is required in these patients.

Level of Evidence

2 Laryngoscope, 2022

Olfactory Training in Post-COVID-19 Persistent Olfactory Disorders: Value Normalization for Threshold but Not Identification

(1) Background: Persistent post-viral olfactory disorders (PPVOD) are estimated at 30% of patients one year after COVID-19 infection. No treatment is, to date, significantly effective on PPVOD with the exception of olfactory training (OT). The main objective of this work was to evaluate OT efficiency on post-COVID-19 PPVOD. (2) Methods: Consecutive patients consulting to the ENT department with post-COVID-19 PPVOD were included after completing clinical examination, the complete Sniffin’ Stick Test (TDI), the short version of the Questionnaire of olfactory disorders and the SF-36. Patients were trained to practice a self-olfactory training with a dedicated olfactory training kit twice a day for 6 months before returning to undergo the same assessments. (3) Results: Forty-three patients were included and performed 3.5 months of OT in average. We observed a significant TDI score improvement, increasing from 24.7 (±8.9) before the OT to 30.9 (±9.8) (p < 0.001). Based on normative data, a significant increase in the number of normosmic participants was observed only for the threshold values (p < 0.001). Specific and general olfaction-related quality of life improved after the OT. (4) Conclusions: Olfactory function appeared to improve only in peripheral aspects of post-COVID-19 PPVOD after OT. Future controlled studies must be performed to confirm the OT role and justify new therapeutic strategies that may focus on the central aspects of post-COVID-19 PPVOD.

A follow-up on quantitative and qualitative olfactory dysfunction and other symptoms in patients recovering from COVID-19 smell loss

BACKGROUND

Sudden smell loss is a specific early symptom of COVID-19, which, prior to the emergence of Omicron, had estimated prevalence of ~40% to 75%. Chemosensory impairments affect physical and mental health, and dietary behavior. Thus, it is critical to understand the rate and time course of smell recovery. The aim of this cohort study was to characterize smell function and recovery up to 11 months post COVID-19 infection.

METHODS

This longitudinal survey of individuals suffering COVID-19-related smell loss assessed disease symptoms and gustatory and olfactory function. Participants (n=12,313) who completed an initial survey (S1) about respiratory symptoms, chemosensory function and COVID-19 diagnosis between April and September 2020, were invited to complete a follow-up survey (S2). Between September 2020 and February 2021, 27.5% participants responded (n=3,386), with 1,468 being diagnosed with COVID-19 and suffering co-occurring smell and taste loss at the beginning of their illness.

RESULTS

At follow-up (median time since COVID-19 onset ~200 days), ~60% of women and ~48% of men reported less than 80% of their pre-illness smell ability. Taste typically recovered faster than smell, and taste loss rarely persisted if smell recovered. Prevalence of parosmia and phantosmia was ~10% of participants in S1 and increased substantially in S2: ~47% for parosmia and ~25% for phantosmia. Persistent smell impairment was associated with more symptoms overall, suggesting it may be a key marker of long-COVID illness. The ability to smell during COVID-19 was rated slightly lower by those who did not eventually recover their pre-illness ability to smell at S2.

CONCLUSIONS

While smell ability improves for many individuals who lost it during acute COVID-19, the prevalence of parosmia and phantosmia increases substantially over time. Olfactory dysfunction is associated with broader persistent symptoms of COVID-19, and may last for many months following acute COVID-19. Taste loss in the absence of smell loss is rare. Persistent qualitative smell symptoms are emerging as common long-term sequelae; more research into treatment options is strongly warranted given that even conservative estimates suggest millions of individuals may experience parosmia following COVID-19. Healthcare providers worldwide need to be prepared to treat post COVID-19 secondary effects on physical and mental health.

Dysosmia Is a Predictor of Motor Function and Quality of Life in Patients with Parkinson's Disease

(1) Background: The correlation between dysosmia with quality of life (QoL) in patients with PD was rarely reported. The study aimed to examine the effect of dysosmia on motor function and QoL in PD. (2) Methods: This cross-sectional study, performed between October 2016 and February 2021, recorded the traditional Chinese version of the University of Pennsylvania Smell Identification Test (UPSIT), the Montreal Cognitive Assessment (MoCA), the Movement Disorder Society-sponsored revision of the Unified Parkinson’s Disease Rating Scale (MDS UPDRS), and the 39-item Parkinson’s Disease Questionnaire (PDQ-39) in patients with PD. UPSIT = 19 was applied to separate the total anosmia and non-anosmia groups. (3) Results: 243 patients with PD were recruited. The total anosmia group had higher MDS UPDRS total, part II, and part III scores than the non-anosmia group. They also had worse scores on the dimensions of activities of daily living (ADL) and cognition of the PDQ-39 than the non-anosmia group. The UPSIT score correlated MDS UPDRS part III score (p < 0.0001), PDQ-39 ADL quartile (p = 0.0202), and Dopamine transporter scan (p = 0.0082) in the linear regression. (4) Conclusions: Dysosmia in PD predicted a phenotype with defective motor function, ADL, and cognition QoL. The findings supported the olfactory transmission of α-synuclein to the cortices, substantia nigra.

Otolaryngic sensory loss as a measure of frailty among older US adults

BACKGROUND

Frailty is a syndrome characterized by reduced physiologic reserve and increased vulnerability to poor health outcomes. Disruption of sensorineural function appears to serve as a novel biomarker of frailty. Using population-level data, we sought to characterize the association between otolaryngic sensory dysfunction and frailty.

METHODS

A cross-sectional analysis of the 2011-2012 US National Health and Nutrition Examination Survey was performed on adults ≥40 years of age (n = 2138). Participants were grouped by subjective gustatory dysfunction (sGD), olfactory dysfunction (sOD), hearing loss (sHL), and measured hearing loss (mHL) with pure tone averages (PTAs). Frailty was operationalized using a continuous 36-item frailty index (FI) scored from 0 to 1, stratified in 4 categories ("non-frail," "vulnerable," "frail," or "most frail").

RESULTS

All sensory loss groups had significantly higher FI scores than those without sensory loss (sGD = 0.15; sOD = 0.14; sHL = 0.15; low-frequency mHL = 0.16; high-frequency mHL = 0.14 vs control = 0.11; p < 0.007 for all). "Vulnerable" individuals had increased odds of sOD (adjusted odds ratio [aOR], 1.45; 95% confidence interval [CI], 1.05-2.00), whereas "frail" individuals had increased odds of sOD (aOR, 1.85; 95% CI, 1.26-2.71) and low-frequency mHL (aOR, 4.01; 95% CI, 1.27-12.63). The "most frail" individuals had increased odds of sHL (aOR, 11.72; 95% CI, 2.88-47.66) and high-frequency mHL (aOR 5.10; 95% CI, 1.72-15.12). PTAs were linearly associated with FI (low: β = 10.15; 95% CI, 1.78-18.51; high: β = 19.85; 95% CI, 5.19-34.53).

CONCLUSION

Otolaryngic sensory loss is associated with increased frailty. Independent association of frailty with measures of olfaction and hearing suggests that olfactory and hearing assessments may help identify at-risk individuals with modifiable risk factors.

Factors associated with anosmia recovery rate in COVID-19 patients

Objectives

The present study aimed to assess the 4- and 8-week recovery rate of anosmia and determine the factors associated with recovery in COVID-19 patients.

Method

This retrospective study was conducted from December 2020 to March 2021. RT-PCR-proven COVID-19 adult patients (over 18 years of age) with a positive history of anosmia were included in this study. Anosmia was assessed based on the COVID-19 Anosmia Reporting Tool. The recovery rate of anosmia after 4 and 8 weeks were evaluated, and the relationship between the patients' recovery and their clinical and demographic data was assessed.

Results

A total of 235 patients were included. Their mean age (±SD) was 43.95 ± 15.27 years. Anosmia recovery was reported in 207(88.51%) and 219 (93.19%) participants till 4 and 8 weeks. The mean recovery time was 19.42 ± 8.81 days. The result of logistic regression showed that smoking (P = .031; OR = 10.813), ageusia (P = .002; OR = 5.340), headache (P = .006; OR = 0.243), and nasal discharge (P < .001; OR = 0.080) were significantly associated with 4 weeks anosmia recovery. The only risk factor which was associated with a lower rate of 8 weeks anosmia recovery was presence of nasal discharge (OR = 0.106, P = .002).

Conclusion

The only risk factor which was associated with a lower rate of 8 weeks anosmia recovery was presence of nasal discharge. Our result demonstrated that although smoking was associated with higher recovery rate till 4 weeks, it could not be considered as a protective factor after 8 weeks. More studies are recommended to investigate the relationship between anosmia and the associated factors by consideration of both short- and long-term recovery rates and assess the possible mechanisms that could justify this association.

Levels of Evidence

3b.

Olfactory dysfunction in passive vs active smoking

BACKGROUND

The aim of this study is to assess the olfactory functions of passive smokers compared to active smokers and nonsmokers.

METHODS

This prospective case-control study included 30 nonsmokers, 30 passive smokers, and 30 active smoker participants. All groups were matched for gender and age. The Sino-Nasal Outcome Test 22 (SNOT-22) and Sniffin' Sticks test battery were administered to all subjects. Threshold (T), discrimination (D), and identification (I) scores were noted. Olfactory function was subjectively assessed as 0: severe dysfunction and 5: no problem.

RESULTS

Overall, TDI scores of active smokers (24.78 ± 3.02) and passive smokers (24.90 ± 2.45) were significantly lower than nonsmokers (34.23 ± 3.46). There was no statistically significant difference between passive smokers and smokers (F (2,87) = 13.47, P < .001)). All subscores are negatively affected by active or passive smoking. The greatest impact of smoking was on threshold scores (η 2 T  = 0.719), followed by identification (η 2 I  = 0.353) and discrimination (η 2 D  = 0.282) scores. SNOT-22 and TDI scores were weakly (r = -.352) correlated as subjective assessment, and TDI scores were moderately correlated (r: .539) (P values < .001). Age and pack-years cigarette dosage had a negative effect on the TDI score (TDI = 26.386 - (0.084 × age) - (0.072 × Pack.Year)) according to stepwise linear regression model (F = 10.187; P = .001).

CONCLUSIONS

Passive smoking has nearly the same adverse effect on olfactory function as active smoking. The threshold scores are the most negatively affected. The olfactory effect of cigarette smoke may not be directly related to nasal inflammation. Olfactory neuronal pathways should be investigated to elucidate the exact pathophysiology.

LEVEL OF EVIDENCE

3b.

Virus load and incidence of olfactory, gustatory, respiratory, gastrointestinal disorders in COVID-19 patients: A retrospective cohort study

OBJECTIVES

This study investigated the relationship between viral load and the incidence of olfactory and gustatory dysfunction (OD and GD), the incidence of respiratory and gastrointestinal symptoms and the recovery of OD and GD in COVID-19 patients.

DESIGN

A retrospective cohort study.

SETTING AND PARTICIPANTS

This study was conducted on 599 outpatients' cases in Golestan province between February and June 2020.

MAIN OUTCOME MEASURES

The incidence, severity (complete or partial) and recovery time of OD and GD and their associations with cycle threshold (CT) values of SARS-CoV-2 polymerase chain reaction were assessed.

RESULTS

The mean age of patients was 38.27 ± 13.62 years. The incidence of general symptoms included myalgia 70.1%, headache 51.8%, fever 47.7% and dyspnoea 21.4%. 41.9% of patients had gastrointestinal symptoms, including abdominal pain 26.5%, diarrhoea 25.2%, nausea 20.5% and vomiting 12.9%. 12.2% of patients had comorbidity. The trimester recovery rates of OD and GD were 93.94% and 94.74% respectively. The mean recovery time of OD and GD was 14.56 ± 13.37 and 13.8 ± 3.77 days respectively. The mean CT value in all patients was 27.45 ± 4.55. There were significant associations between the mean of CT value with headache (p = 0.04), GD (p = 0.002) and OD (p = 0.001).

CONCLUSIONS

The finding of this study indicates a possible association between viral load with incidence of OD and GD in COVID-19 patient's cases and assures the recovery of OD/GD in these patients.

Virus load and incidence of olfactory, gustatory, respiratory, gastrointestinal disorders in COVID-19 patients: A retrospective cohort study

Objectives

This study investigated the relationship between viral load and the incidence of olfactory and gustatory dysfunction (OD and GD), the incidence of respiratory and gastrointestinal symptoms and the recovery of OD and GD in COVID‐19 patients.

Design

A retrospective cohort study.

Setting and Participants

This study was conducted on 599 outpatients' cases in Golestan province between February and June 2020.

Main Outcome Measures

The incidence, severity (complete or partial) and recovery time of OD and GD and their associations with cycle threshold (CT) values of SARS‐CoV‐2 polymerase chain reaction were assessed.

Results

The mean age of patients was 38.27 ± 13.62 years. The incidence of general symptoms included myalgia 70.1%, headache 51.8%, fever 47.7% and dyspnoea 21.4%. 41.9% of patients had gastrointestinal symptoms, including abdominal pain 26.5%, diarrhoea 25.2%, nausea 20.5% and vomiting 12.9%. 12.2% of patients had comorbidity. The trimester recovery rates of OD and GD were 93.94% and 94.74% respectively. The mean recovery time of OD and GD was 14.56 ± 13.37 and 13.8 ± 3.77 days respectively. The mean CT value in all patients was 27.45 ± 4.55. There were significant associations between the mean of CT value with headache (p = 0.04), GD (p = 0.002) and OD (p = 0.001).

Conclusions

The finding of this study indicates a possible association between viral load with incidence of OD and GD in COVID‐19 patient's cases and assures the recovery of OD/GD in these patients.

Barriers to effective health care for patients who have smell or taste disorders

Objectives

Smell/taste disturbances are a common but underrated, under‐researched and under treated sensory loss and an independent risk factor for reduced longevity. This study aimed to characterise the experience of patients with these disorders in seeking help.

Design

The study was designed by patients together with clinicians through a dedicated workshop and conducted as a cross‐sectional survey to capture experiences in public and private healthcare settings internationally.

Setting

Primary, secondary and tertiary care.

Participants

Any members of the public self‐reporting a smell/taste disorder were invited to participate.

Main outcome measures

The survey captured information including experience of getting consultations and referrals to medical professionals, treatments offered, costs incurred and related problems with mental health.

Results

Of 673 participants; 510 female, 160 male, three not stated, self‐reported aetiology included sinonasal disease (24%), idiopathic (24%) and post‐viral olfactory dysfunction (22%); true gustatory disorders were typically rare. Failure of medical professionals to recognise the problem was a key concern ‐ 64%, 76% and 47% of GPs, ENT specialists and Neurologists acknowledged, respectively. Other issues included repeated ineffective treatments, difficulties getting referrals to secondary/tertiary care, mental health problems (60%) and a mean personal cost of £421 to seeking advice and treatment. Whilst the participants were self‐selecting, however, they do represent those who are seeking help and intervention for their disorders.

Conclusion

There is an unmet need for these patients in accessing health care including a clear need to improve education of and engagement with the medical profession in Otorhinolaryngology, General Practice and other specialties, in order to remove the current barriers they face.

Association between social determinants of health and olfactory function: a scoping review

BACKGROUND

Social determinants of health (SDoH) include the socioeconomic, demographic, and social conditions that influence differences in health status among individuals and groups. The impact of these conditions on olfactory function remains poorly understood. In this scoping review, we systematically review the available literature to synthesize the association between SDoH and olfactory function.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Review (PRISMA-ScR) guidelines, we performed systematic search queries in PubMed, Embase, and Ovid databases and categorized articles according to themes that emerged regarding SDoH. The primary outcomes included self-reported and objective measurements of smell.

RESULTS

We identified 722 unique references that underwent title and abstract review by two independent reviewers, with 70 articles undergoing full-text review and 57 relevant for data extraction. Six themes emerged in our review, under which we categorized the studies and synthesized respective associations with olfactory function. These include studies exploring socioeconomic status (n = 19, 33%), education status (n = 27, 47%), occupational exposures (n = 26, 46%), racial/ethnic disparities (n = 12, 21%), and lifestyle/behavioral factors (n = 33, 58%).

CONCLUSIONS

Within the context of this scoping review, olfactory dysfunction is significantly more prevalent in patients with lower socioeconomic status, exposure to environmental and occupational toxins, and of minority race/ethnicity, whereas the associations between olfactory dysfunction and education level and lifestyle factors such as smoking and drinking seem to be much more elusive. This review highlights the importance of accounting for SDoH in observational studies examining olfactory outcomes. Given the increased awareness of olfactory loss, special consideration should be given to understanding olfactory dysfunction in the context of these factors.

Psychometric properties of the brief version of the questionnaire of olfactory disorders in patients with chronic rhinosinusitis

BACKGROUND

The Questionnaire of Olfactory Disorders-Negative Statements (QOD-NS) is a 17-item instrument measuring olfactory-specific quality of life (QOL). However, in clinical research patients can be overwhelmed with multiple questionnaires. We recently developed the 7-item brief QOD-NS (B-QOD). Our objective was to evaluate the psychometric properties of the B-QOD in both the development (D) sample, and in a separate replication (R) sample.

METHODS

Testing on D (n = 203) and R (n = 281) samples included initial exploratory factor analysis (EFA), followed by internal reliability, information loss, and confirmatory factor analysis (CFA). Finally, incremental predictive utility analysis (IPUA) was performed by correlating the B-QOD with the 22-item Sino-Nasal Outcome Test (SNOT-22) survey.

RESULTS

EFAs of both D and R demonstrated an underlying single-factor structure (eigenvalue = 4.17 and 3.57, respectively) with comparable loading factors (R > 0.30 for both). B-QOD also had good internal reliability in both D and R (Cronbach's alpha = 0.88 and 0.83, respectively). Also, there is minimal information loss with B-QOD compared to QOD-NS in both D and R (R = 0.98 and 0.96, respectively). CFA indicates that the B-QOD single-factor model has good overall fit as measured by the Comparative Fit Index (CFI) and the Standardized Root Mean Squared Residuals (SRMSR) in the D and R samples (CFI = 0.99 and 0.97; SRMSR = 0.035 and 0.053). IPUA shows that the QOD-NS offers no additional predictive benefit of SNOT-22 scores when compared with B-QOD.

CONCLUSION

The 7-item B-QOD captures a structurally coherent and reliable single dimension, with minimal information loss and excellent external predictive utility when compared to the QOD-NS.

[Research progress in the treatment of sensorineural olfactory dysfunction]

Sensorineural olfactory dysfunction refers to the reduction or distortion of sensory intensity due to insufficient reception or processing of stimulation by olfactory receptors, olfactory sensory neurons or central nervous system. As olfactory dysfunction can affect patients' physical and mental health and even safety of life and the etiology of sensorineural olfactory dysfunction is complicated, it has great clinical significance for understanding the development of olfactory dysfunction's treatment. This article summarizes the current promising treatment for sensorineural olfactory dysfunction, including drug therapy, cell therapy, gene therapy and olfactory training.

Neurological symptoms in Covid-19 patients in the emergency department

BACKGROUND

Coronavirus disease 2019 (Covid-19) might present neurological symptoms. We aimed to evaluate the frequency of them at the moment of emergency department (ED) visit and their impact in the prognosis.

METHODS

Retrospective cohort study including all consecutive hospitalized cases between March 8th and April 11th, 2020. Covid-19 diagnosis was confirmed by polymerase chain reaction test and/or serology. We compared, in patients with and without neurological symptoms on admission, demographic, clinical presentation, and frequency and type of abnormal laboratory values. We analyzed the variables that were associated with in-hospital all-cause mortality by Cox-regression log-rank test.

RESULTS

We included 576 hospitalized patients, 250 (43.3%) female, aged 67.2 years. At the moment of ED visit, 320 (55.6%) described neurological symptoms, including anosmia (146, 25.3%), myalgia (139, 24.1%), headache (137, 23.8%), and altered mental status (98, 17.0%). Neurological symptoms started the first symptomatic day in 198 (54.2%) cases. Patients with neurological symptoms presented later to the ED (7.9 versus. 6.6 days, p = .019). Only four (0.6%) cases had no typical Covid-19 general symptoms, and only six (1.9%) had a normal laboratory results, for a sensitivity of 98.7% (95% confidence interval (CI): 96.6%-99.6%) and 98.1% (95% CI: 95.7%-99.2%), respectively. In the multivariate Cox-regression of mortality predictors, anosmia (HR: 0.358, 95%CI: 0.140-0.916) and altered mental status (HR: 1.867, 95%CI: 1.162-3.001) were significant.

CONCLUSION

Neurological symptoms were the most frequent extrapulmonary symptoms. They were present in half of the Covid-19 patients at the time of the ED visit. Anosmia on admission was an independent predictor of lower in-hospital mortality and altered mental status on admission predicted in-hospital mortality.

Incidence of smell and taste disorders and associated factors in patients with mild to moderate COVID-19

&lt;b&gt;Objectives:&lt;/b&gt; To determine the incidence of smell and taste disorders in our health department and to analyse the factors that could be associated with these symptoms in patients with COVID-19. &lt;br&gt;&lt;b&gt;Methods:&lt;/b&gt; We conducted an observational descriptive study of all patients with COVID-19 in our health area diagnosed between 2020/03/10 and 2020/04/14. Factors related to smell and taste disorders were analysed. &lt;br&gt;&lt;b&gt;Results:&lt;/b&gt; A total of 126 patients, 63 women and 63 men, aged 16-80 years, were included. As many as 69 patients (62.7%) presented hyposmia, and 58 (46%) of them had anosmia. A total of 75 patients (59.5%) presented hypogeusia, and 57 (45.2%) of them had ageusia. The risk factors that were most commonly associated with these disorders were the female sex (adjusted odds ratio, aOR 2.43 for smell disorders and 2.44 for taste disorders), allergic rhinitis (aOR 3.34 for smell disorders) and a younger age. A protective factor was arterial hypertension (aOR 0.51 for smell disorders and 0.35 for taste disorders). A history of tonsillectomy was the risk factor for taste disorder (aOR 5.23). &lt;br&gt;&lt;b&gt;Conclusion:&lt;/b&gt; Our results indicate that these sensory disorders occurred more frequently in female patients and in young patients with mild to moderate COVID-19 infection who progressed with mild nasal congestion, posterior rhinorrhoea and without anterior rhinorrhoea. The recovery of taste occurred before the recovery of smell.

Olfactory Dysfunction in Frontline Health Care Professionals During COVID-19 Pandemic in Brazil

Upper respiratory viral infections can decrease the sense of smell either by inflammatory restriction of nasal airflow that carries the odorant molecules or through interference in olfactory sensory neuron function. During the coronavirus disease 2019 (COVID-19) pandemic, triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), worldwide reports of severe smell loss (anosmia/hyposmia) revealed a different type of olfactory dysfunction associated with respiratory virus infection. Since self-reported perception of smell is subjective and SARS-CoV-2 exposure is variable in the general population, we aimed to study a population that would be more homogeneously exposed to the virus. Here, we investigated the prevalence of olfactory loss in frontline health professionals diagnosed with COVID-19 in Brazil, one of the major epicenters of the disease. We also analyzed the rate of olfactory function recovery and the particular characteristics of olfactory deficit in this population. A widely disclosed cross-sectional online survey directed to health care workers was developed by a group of researchers to collect data concerning demographic information, general symptoms, otolaryngological symptoms, comorbidities, and COVID-19 test results. Of the 1,376 health professionals who completed the questionnaire, 795 (57.8%) were working directly with COVID-19 patients, either in intensive care units, emergency rooms, wards, outpatient clinics, or other areas. Five-hundred forty-one (39.3%) participants tested positive for SARS-CoV-2, and 509 (37%) were not tested. Prevalence of olfactory dysfunction in COVID-19-positive subjects was 83.9% (454 of 541) compared to 12.9% (42 of 326) of those who tested negative and to 14.9% (76 of 509) of those not tested. Olfactory dysfunction incidence was higher in those working in wards, emergency rooms, and intensive care units compared to professionals in outpatient clinics. In general, remission from olfactory symptoms was frequent by the time of responses. Taste disturbances were present in 74.1% of infected participants and were significantly associated with hyposmia. In conclusion, olfactory dysfunction is highly correlated with exposure to SARS-CoV-2 in health care professionals, and remission rates up to 2 weeks are high.

Olfactory function and findings on chest computed tomography in COVID-19: is there any correlation?

BACKGROUND

Olfactory dysfunction is frequent in COVID-19 and it might occur along with pulmonary involvement. These manifestations do not seem to share pathophysiological mechanisms, but clinical data on the subject is lacking. Aims/Objectives: This study aims to correlate the olfactory function (OF) and the radiological pulmonary involvement among in-hospital patients with COVID-19.

MATERIALS AND METHODS

Patients hospitalized with severe COVID-19 were consecutively recruited. They had their objective OF evaluated by the Alcohol Sniff Test and underwent a chest computed tomography (cCT). Qualitative and quantitative analyses of the cCT scans were performed by a blinded radiologist. The quantitative assessment included both the grade of involved parenchyma and the CT severity score (CT-SS). Data obtained were then compared.

RESULTS

57 patients were included. There was no correlation between the OF and the grade of lung involvement (p-value: .884) or the CT-SS (Pearson's coefficient: -.111). Yet, patients with radiological findings on the cCT typical for COVID-19 did not present significantly different OF from the remaining (p-value: .193). Conclusions: Olfactory dysfunction does not correlate with the radiological lung involvement in patients hospitalized with COVID-19.

SIGNIFICANCE

There is also clinical evidence that the olfactory disorder and the pulmonary disease in COVID-19 have distinct mechanisms.

Supplemental data for this article is available online at here.

Investigation of Normative Value of Commercialized Taiwan Smell Identification Test

Background

The Taiwan Smell Identification Test (TWSIT) was developed and successfully administered in Taiwanese population since 2015. However, for sanitation reason, the original liquid-jar form of this test is not appropriate. The commercialized TWSIT was then re-designed as “scratch-and-sniff” version: the TIBSIT (Top International Biotech, Taipei, Taiwan). This project aims to investigate the normative value of TIBSIT in different age groups and genders.

Methods

Volunteers aged 20 to 80 with no subjective smell loss were recruited in a rhinology clinic. The participants were given full instructions on using the TIBSIT.

Results

Two hundred and nine healthy subjects (female: male =107: 102) were enrolled into this study. The median TIBSIT score in female and male subjects is 47 and 46, respectively. Subjects were further divided into three age groups: (A) 20∼34 years (n = 77), (B) 35∼54 years (n = 77), and (C) 55∼80 years (n = 55). The TIBSIT scores at the tenth percentile value at each age group of male patients are 43, 42 and 37; while the scores at the tenth percentile value at each age group of female patients are 42, 42 and 41. TIBSIT score was significantly and inversely correlated with age (Spearman rho = − 0.20, p = 0.004.).

Conclusion

We established the normative values of the new TIBSIT in different age groups in Taiwan. Future nation-wide screening is needed for more sophisticated norms establishment.

Congenital Agenesis of the Olfactory Bulbs: What to Suspect?

Complete agenesis of the olfactory bulbs (OB) constitutes a rare cause of congenital anosmia, which is more often associated with cerebral malformations or genetic disorders. The authors present a very rare case of a 28-year-old caucasian male with complaints of complete lack of the sense of smell since childhood. Radiologic study confirmed complete bilateral agenesis of the OB, with no other radiologic or clinical findings, such as delayed sexual development. Laboratorial investigation confirmed no signs of adrenocortical insufficiency. Despite being immature in the term neonate, the OB are already functional at birth. Congenital agenesis of the OB can occur as an isolated deformity. On the other hand, it is a constant feature of several genetic syndromes, such as Kallmann's syndrome or alobar holoprosencephaly. Most cases of isolated congenital anosmia occur sporadically, with no family history of the condition. Given the fact that no curative treatment is available, counselling for daily living precautions should be given to all patients. This is one of the first case reports about complete and isolated agenesia of the OB diagnosed in adulthood. The authors highlight the need to exclude several genetic syndromes that may be associated, albeit in a dissimulated way.

Olfactory Dysfunction in Huntington's Disease

Olfactory dysfunction is a common symptom in patients with neurodegenerative disorders, including Huntington's disease (HD). Understanding its pathophysiology is important in establishing a preventive and therapeutic plan. In this literature review, we cover the physiology of olfaction, its role in neurodegeneration, and its characteristics in patients with HD. In the general population, olfactory dysfunction is present in 3.8-5.8%and the prevalence increases significantly in those older than 80 years. For HD, data regarding prevalence rates are lacking and the scales used have been inconsistent or have been restructured due to concerns about cross-cultural understanding. Pathogenic huntingtin deposits have been found in the olfactory bulb of individuals with HD, although no studies have correlated this with the grade of olfactory impairment. Olfactory dysfunction is present in both premanifest and manifest patients with HD, showing a progressive decline over time with more severe deficits at advanced stages. No specific treatment for olfactory impairment in HD has been proposed; identifying and avoiding potential medications that cause olfactory dysfunction, as well as general safety recommendations remain the basis of the therapeutic strategy.

The association of frailty with olfactory and gustatory dysfunction in older adults: a nationally representative sample

BACKGROUND

Olfaction and gustation are associated with age-related decline. Deficits in these chemosenses have been associated with significant comorbidities. Meanwhile, frailty, defined as a reduced physiological reserve, is well correlated with mortality and worse health outcomes. We sought to analyze a nationally representative patient population to determine the association between chemosensory dysfunction and frailty.

METHODS

Cross-sectional analysis of U.S. National Health and Nutrition Examination Survey (NHANES) 2013-2014 was performed, using multivariate logistic regression to examine the association between chemosensory dysfunction and frailty in adults aged ≥40 years (n = 3547). Self-reported olfactory dysfunction (sOD) and gustatory dysfunction (sGD), and measured olfactory dysfunction (mOD) and gustatory dysfunction (mGD) were assessed for all participants. Frailty was operationalized using a 39-item frailty index (FI) and stratified into 4 groups using validated cutoffs.

RESULTS

Participants with sOD and mOD had significantly higher mean FI scores (sOD: 0.18 vs 0.13, p < 0.001; mOD: 0.20 vs 0.14, p < 0.001), whereas subjects with sGD, but not mGD, had higher mean FI scores (sGD: 0.21 vs 0.13, p < 0.001; mGD: 0.14 vs 0.14, p = 0.953). Multivariate logistic regression demonstrated frail participants had significantly greater odds of sGD (odds ratio [OR] 4.11; 95% confidence interval [CI], 3.46 to 4.88), sOD (OR 2.35; 95% CI, 1.98 to 2.78), and mOD (OR 1.58; 95% CI, 1.22 to 2.05), but not mGD (OR 1.21; 95% CI, 0.91 to 1.61). This association was strongest in the frailest group.

CONCLUSION

Self-reported chemosensory dysfunction and mOD are independently associated with measures of frailty, suggesting a novel method to assess or predict frailty.

Headache associated with COVID-19: Frequency, characteristics and association with anosmia and ageusia

OBJECTIVES

To assess the frequency and characteristics of headache in patients with COVID-19 and whether there is an association between headache and anosmia and ageusia.

METHODS

This was a cross-sectional study. Consecutive patients admitted to hospital with COVID-19, confirmed by reverse transcription polymerase chain reaction (RT-PCR) technique, were assessed by neurologists.

RESULTS

Seventy-three patients were included in the study, 63% were male; the median age was 58 years (IQR: 47-66). Forty-seven patients (64.4%) reported headaches, which had most frequently begun on the first day of symptoms, were bilateral (94%), presenting severe intensity (53%) and a migraine phenotype (51%). Twelve patients (16.4%) presented with headache triggered by coughing. Eleven (15%) patients reported a continuous headache. Twenty-eight patients (38.4%) presented with anosmia and 29 (39.7%) with ageusia. Patients who reported hyposmia/anosmia and/or hypogeusia/ageusia experienced headache more frequently than those without these symptoms (OR: 5.39; 95% CI:1.66-17.45; logistic regression). Patients with anosmia and ageusia presented headache associated with phonophobia more often compared to those with headache without these complaints (Chi-square test; p < 0.05). Headache associated with COVID-19 presented a migraine phenotype more frequently in those experiencing previous migraine (p < 0.05).

CONCLUSION

Headaches associated with COVID-19 are frequent, are generally severe, diffuse, present a migraine phenotype and are associated with anosmia and ageusia.

Olfactory Function After Surgical Treatment of CRS: A Comparison of CRS Patients to Healthy Controls

BACKGROUND

Many patients with chronic rhinosinusitis (CRS) have persistent olfactory dysfunction (OD) following endoscopic sinus surgery (ESS). Few studies compare outcomes to control subjects so it is unknown if residual OD is due to persistent CRS.

OBJECTIVE

Compare postoperative measures of OD in case patients with CRS to healthy controls without sinonasal disease.

METHODS

Prospective, observational, multicenter cohort study between October, 2016 and May, 2019. Case participants were selected from referred adult patients diagnosed with CRS, with or without nasal polyposis (NP), electing ESS as subsequent treatment modality. Controls voluntarily enrolled from a community-based sample without a history of CRS. Primary outcomes included measures of preoperative and postoperative OD using "Sniffin' Stick" pens which summarize odorant threshold (T), discrimination (D), and identification (I) scores. Secondary outcomes included the Questionnaire of Olfactory Disorders-Negative Statements (QOD-NS) survey and olfactory cleft endoscopy scores (OCES).

RESULTS

Outcomes were compared between 113 cases and 164 controls of similar average age and gender. Cases reported significantly worse baseline Sniffin' Sticks TDI total scores (-6.8[SE ± 1.0]; 95% CI: -4.9 to -8.7), QOD-NS (8.9[SE ± 1.1]; 95% CI: 6.8-10.9), and OCES (3.5[SE ± 0.4]; 95% CI: 2.9-4.2) on average. Cases reported significant postoperative improvement in TDI total score (3.7[SD ± 8.2]; 95% CI: 2.2-5.2), QOD-NS (-5.9[SD ± 8.7]; 95% CI: -7.6 to -4.3), and OCES (-1.7[SD ± 3.8]; 95% CI: -2.7 to -0.8) on average, while 63% of anosmics reported improved postoperative olfaction. Multivariate regression identified that NP (OR = 0.4; 95% CI: 0.2-1.0) and previous ESS (OR = 0.3; 95% CI: 0.1-0.8) decreased the odds of postoperative improvement equal to mean TDI scores of controls, while septoplasty increased those odds (OR = 4.5; 95% CI: 1.5-13.7).

CONCLUSION

ESS improved olfactory metrics and restored olfactory function in approximately 50% of patients with CRS to that of healthy controls. Concurrent septoplasty increased the likelihood of achieving normal olfaction, while NP and previous ESS decreased those odds.

Is loss of sense of smell a diagnostic marker in COVID-19: A systematic review and meta-analysis

Aims

To systematically review the currently available evidence investigating the association between olfactory dysfunction (OD) and the novel coronavirus (COVID‐19). To analyse the prevalence of OD in patients who have tested positive on polymerase chain reaction (PCR) for COVID‐19. To perform a meta‐analysis of patients presenting with olfactory dysfunction, during the pandemic, and to investigate the positive predictive value for a COVID‐19‐positive result in this population. To assess whether olfactory dysfunction could be used as a diagnostic marker for COVID‐19 positivity and aid public health approaches in tackling the current outbreak.

Methods

We systematically searched MedLine (PubMed), Embase, Health Management Information Consortium (HMIC), Medrxiv, the Cochrane Library, the Cochrane COVID‐19 Study Register, NIHR Dissemination centre, Clinical Evidence, National Health Service Evidence and the National Institute of Clinical Excellence to identify the current published evidence which associates coronaviridae or similar RNA viruses with anosmia. The initial search identified 157 articles. A total of 145 papers were excluded following application of our exclusion criteria. The 12 remaining articles that presented evidence on the association between COVID‐19 and olfactory dysfunction were critically analysed.

Results

Olfactory dysfunction has been shown to be the strongest predictor of COVID‐19 positivity when compared to other symptoms in logistic regression analysis. In patients who had tested positive for COVID‐19, there was a prevalence of 62% of OD. In populations of patients who are currently reporting OD, there is a positive predictive value of 61% for a positive COVID‐19 result.

Conclusion

Our review has shown that there is already significant evidence which demonstrates an association between OD and the novel coronavirus—COVID‐19. It is unclear if this finding is unique to this coronavirus as individual viral phenotypes rarely present in such concentrated large numbers. We have demonstrated that OD is comparatively more predictive for COVID‐19 positivity compared to other associated symptoms. We recommend that people who develop OD during the pandemic should be self‐isolate and this guidance should be adopted internationally to prevent transmission.

Treatment of posttraumatic olfactory dysfunction with corticosteroids and olfactory training

Background: Few have investigated long-term effect of treatment of posttraumatic olfactory dysfunction (OD).Aims/objectives: To explore if sequential treatment with corticosteroids and olfactory training (OT) improved smell in patients with OD after moderate and severe traumatic brain injury (TBI).Material and methods: Twenty-two patients with persistent OD, mean 62 months after trauma, completed an open uncontrolled intervention study of treatment for 10 d with oral corticosteroids and thereafter for 3 months with OT twice daily. Olfaction was assessed by Sniffin' Sticks. They were tested at four-time points, with the last assessment 12 months after baseline measurements.Results: Mean age at trauma was 45 (SD 14) years. Mean threshold, discrimination and identification (TDI) score at baseline was 14.4 (SD 7.3) and increased to mean 20.8 (SD 7.4) after 1 year (minimum -3.0; maximum 19.5, p value <.001). Analysed separately, each TDI component increased significantly after 1 year. Half of the patients (11/22) experienced a clinically significant improvement of ≥6.0 TDI points. Improvement was not associated with any sociodemographic or trauma-related characteristics or with olfactory function at baseline.Conclusions and significance: Treatment with corticosteroids and OT was promising in persistent OD after TBI and should be further studied.

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.

Reversal of Olfactory Disturbance in Allergic Rhinitis Related to OMP Suppression by Intranasal Budesonide Treatment

PURPOSE

We evaluated the severity of olfactory disturbance (OD) in the murine model of allergic rhinitis (AR) and local allergic rhinitis (LAR) in mice. We also investigated the therapeutic effect of an intranasal steroid on OD.

METHODS

Forty BALB/c mice were divided into 5 groups (n = 8 for each). The control group was sensitized intraperitoneally (i.p.) and challenged intranasally (i.n.) with saline. Mice in the AR group got i.p. and i.n. ovalbumin (OVA) administration for AR induction. The LAR group was challenged i.n. with 1% OVA for inducing local nasal allergic inflammation, without inducing the systemic allergy. The OD group got an i.p. methimazole administration (75 mg/kg) to induce total destruction of olfactory mucosa. Mice in the intranasal budesonide group received i.n. budesonide (12.8 μ per time, 30 minutes after the i.n. OVA challenge) while using OVA to cause systemic allergies. We conducted a buried-food pellet test to functionally assess the degree of OD in each group by measuring the time taken until finding hidden food. We evaluated the damage to olfactory epithelium using histopathologic evaluation and compared the degree of olfactory marker protein (OMP) expression in olfactory epithelium using immunofluorescent staining.

RESULTS

Mice of the AR (81.3 ± 19.8 seconds) and LAR groups (66.2 ± 12.7 seconds) spent significantly more time to detect the pellets than the control group (35.6 ± 12.2 seconds, P < 0.01). After treatment, the intranasal budesonide group exhibited significantly better results (35.8 ± 11.9 seconds) compared with the AR and LAR groups (P < 0.01). The AR and LAR groups showed considerable olfactory epithelial damage and suppression of OMP expression compared with the control group. In the intranasal budesonide group, the olfactory lesions and OMP expression had improved substantially.

CONCLUSIONS

OD may be caused by olfactory epithelial damage and suppression of OMP expression in nasal allergic inflammation and could be reversed using an intranasal steroid.

[Using of ¹⁸F-FDG to evaluate the effect of traumatic olfactory nerve injury on drug delivery through the nasal-brain pathway: a PET-MRI pilot study]

Objective:This study evaluated the effect of traumatic olfactory nerve injury on drug delivery through the nasal-brain pathway via the instillation of ¹⁸F-FDG at the olfactory cleft. Method:Seven healthy volunteers and 5 patients with traumatic dysosmia were enrolled in the study. Subjects were all instilled with ¹⁸F-FDG on each side of the olfactory cleft under endoscopy. After 12 hours, a PET/MR scan was performed to track the metabolism pathway of ¹⁸F-FDG. Then, we compared the diameter of the olfactory bulb and the olfactory bulb intake between normal volunteers and patients with traumatic olfactory disorders. Result:In healthy volunteers, there was a significant difference in ¹⁸F-FDG uptake between the regions of interest in which ¹⁸F-FDG was or was not in contact with the cribriform plate（P=0.012 7）; this difference also existed in patients with traumatic olfactory disorders（P=0.038 1）. Patients with traumatic olfactory disorders did not exhibit significant differences in ¹⁸F-FDG uptake in the region of interest compared with healthy volunteers（P=0.937 2）. Conclusion:The olfactory bulb is obviously atrophied in patients with traumatic olfactory dysfunction, and the uptake of ¹⁸F-FDG in the olfactory bulb region of interest is also reduced. The administration of ¹⁸F-FDG via olfactory fissure area can enter olfactory bulb and parafrontal tissues through the nasal brain pathway,¹⁸F-FDG can enter the central nervous system through the nasal-brain pathway, which is not affected by olfactory nerve transection injury.

The Changing Landscape of Parkinson Epidemiologic Research

Despite recent successes in understanding the genetics of Parkinson’s disease (PD), the causes of late-onset sporadic PD remain elusive. Many of the epidemiologic findings on PD etiology have been challenged by alternative explanations such as reverse causation. This is mainly because PD often takes decades to develop before it can be diagnosed late in life. Convincing evidence shows that this prodromal stage of PD is characterized by various prodromal symptoms such as olfactory impairment and rapid-eye-movement sleep behavior disorder (RBD). As they likely reflect PD pathogenesis years, if not decades, before nigrostriatal involvement, research on these symptoms may represent an unprecedented opportunity to dissect the etiology of PD. Using PD prodromal symptoms as intermediate phenotypes, we may be able to identify factors that contribute to the development of these symptoms and factors that modify their progression to clinical PD. Further, this line of research will also enable examinations of novel etiological hypotheses of PD development such as the microbiome and prion hypotheses. In this article, the author used olfactory impairment and RBD as examples to illustrate the promises and challenges of epidemiologic research on prodromal symptoms to understand PD etiology.

[Advances in etiology and pathogenic mechanisms of postviral olfactory dysfunction]

Postviral olfactory disorders(PVOD) are one of the most commonly identified causes of olfactory dysfunction. However, its causative agent has yet been identified even though techniques of virus detection have been improved rapidly. It has been reported that some kinds of viruses are able to infect the olfactory neurons directly and result in the infection of central nervous system via olfactory pathway, which suggest the complexity of the pathogenic mechanism of PVOD. In the article, we review the advance in virus identification and pathogenesis of PVOD, which might be helpful to the diagnosis and treatment.

Olfactory impairment in frontotemporal dementia: A systematic review and meta-analysis

Frontotemporal dementia (FTD) presents clinically in three variants: one behavioral and two with progressive primary aphasia - non-fluent/agrammatic and semantic. Defined by the degenerative process and cerebral atrophy, olfactory dysfunction occurs in up to 96% of previous FTD case series.

Objective

the present study aims to critically synthesize data about the relationship between FTD and olfactory impairment to analyze the usefulness of olfactory evaluation tests as a complementary element in early diagnosis.

Methods

a database search was performed using the keywords "olfactory OR smell OR olfaction AND frontotemporal dementia". We included studies that evaluated olfactory function in patients diagnosed with frontotemporal dementia, all subtypes, compared with age-matched healthy controls. For comparative purposes, the effect size was calculated using Cohen's D. The studies selected were categorized according to dementia variant and olfactory test type. A meta-analysis was performed using forest plots - homogeneity was evaluated by statistical tests (i² and Cochran Q).

Results

ten articles met the inclusion criteria. Heterogeneity was classified as low for semantic dementia olfactory identification and behavioral variant olfactory discrimination groups (i² = 0 and 3.4%, respectively) and as moderate for the behavioral variant olfactory identification group (i² = 32.6%).

Conclusion

patients with the frontotemporal dementia behavioral variant seem to present with alterations in odor identification, but with preserved discrimination. Scent identification also seems to be impaired in semantic dementia. Therefore, we conclude that olfactory evaluation in these patients is possibly impacted by cognitive alterations and not by sensory deficits. Application of olfactory tests may prove important in differentiating prodromal states from other types of dementia with more pronounced olfactory impairment.