Prevalence and 24-month recovery of olfactory dysfunction in COVID-19 patients: A multicentre prospective study

Seawater nasal wash to reduce symptom duration and viral load in COVID-19 and upper respiratory tract infections: a randomized controlled multicenter trial

PURPOSE

The objective was to assess the efficacy of seawater nasal wash on symptom duration, intranasal viral load, household transmission in COVID-19 and URTIs.

METHODS

This prospective, randomized, controlled, multicentric, parallel study included 355 mild/moderate COVID-19 and URTI adults with rhinologic symptoms ≤ 48h. Active group performed 4-daily nasal washes with undiluted isotonic seawater versus control group (without nasal wash). Symptoms were self-assessed daily using the WURSS-21 questionnaire for 3 weeks. Viral load was measured by RT-PCR on nasopharyngeal swabs collected on Day 0, Day 5, Day 14 and Day 21. Digital droplet PCR was additionally performed for SARS-CoV-2.

RESULTS

Overall COVID-19 subjects recovered earlier the ability to accomplish daily activities in the active group (- 1.6 day, p = 0.0487) with earlier improvement of taste (- 2 days, p = 0.0404). COVID-19 subjects with severe nasal symptoms at D0 showed the earliest resolution of anosmia (- 5.2 days, p = 0.0281), post-nasal drip (- 4.1 days, p = 0.0102), face pain/heaviness (- 4.5 days, p = 0.0078), headache (- 3.1 days, p = 0.0195), sore throat (- 3.3 days, p = 0.0319), dyspnea (- 3.1 days, p = 0.0195), chest congestion (- 2.8 days, p = 0.0386) and loss of appetite (- 4.5 days, p = 0.0186) with nasal wash. In URTIs subjects, an earlier resolution of rhinorrhea (- 3.5 days, p = 0.0370), post-nasal drip (- 3.7 days, p = 0.0378), and overall sickness (- 4.3 days, p = 0.0248) was reported with nasal wash. Evolution towards more severe COVID-19 was lower in active vs control, with earlier viral load reduction in youngest subjects (≥ 1.5log10 copies/10000 cells at Day 5: 88.9% vs 62.5%, p = 0.0456). In the active group, a lower percentage of SARS-CoV-2 positive household contacts (0-10.7%) was reported vs controls (3.2-16.1%) among subjects with Delta variant (p = 0.0413).

CONCLUSION

This trial showed the efficacy and safety of seawater nasal wash in COVID-19 and URTIs.

TRIAL REGISTRATION

Trial registry ClinicalTrials.gov: NCT04916639. Registration date: 04.06.2021.

Parosmia in patients with post-infectious olfactory dysfunction in the era of COVID-19-associated olfactory impairment

OBJECTIVES

A large number of patients with olfactory impairment are affected by parosmia or phantosmia. This study aimed to examine the demographic and clinical characteristics of parosmia.

METHODS

We performed a retrospective data analysis of patients consulting at our Smell and Taste Outpatient Clinic. A total of 297 patients were included (203 women, mean age 44.4 ± 13.7 years). Olfactory function was quantified using the "Sniffin' Sticks" composite TDI (odor threshold, determination, and identification) score. The presence of qualitative olfactory impairment was assessed trough medical history and a parosmia questionnaire.

RESULTS

Most of the patients showed olfactory impairment after an infection with SARS-CoV‑2 (84%) and were diagnosed with parosmia (49%). Patients with parosmia (PAR) (n = 201) were significantly younger compared to the group without parosmia (noPAR; n = 92) (PAR 43.2 ± 13 years vs. noPAR 47 ± 15.1 years, p = 0.03) and had a slightly shorter duration of disease, without reaching statistical significance (PAR 10.3 ± 4.9 months, noPAR 13.6 ± 37.6 months, p = 0.23). They also had higher TDI scores (PAR 24.3 ± 7 points, noPAR 21.4 ± 8.2 points, p = 0.003).

CONCLUSIONS

Patients affected by parosmia were younger and had a better olfactory function compared to patients without parosmia.

Brain microstructure and connectivity in COVID-19 patients with olfactory or cognitive impairment

INTRODUCTION

The COVID-19 pandemic has affected millions worldwide, causing mortality and multi-organ morbidity. Neurological complications have been recognized. This study aimed to assess brain structural, microstructural, and connectivity alterations in patients with COVID-19-related olfactory or cognitive impairment using post-acute (time from onset: 264[208-313] days) multi-directional diffusion-weighted MRI (DW-MRI).

METHODS

The study included 16 COVID-19 patients with cognitive impairment (COVID-CM), 35 COVID-19 patients with olfactory disorder (COVID-OD), and 14 controls. A state-of-the-art processing pipeline was developed for DW-MRI pre-processing, mean diffusivity and fractional anisotropy computation, fiber density and cross-section analysis, and tractography of white-matter bundles. Brain parcellation required for probing network connectivity, region-specific microstructure and volume, and cortical thickness was based on T1-weighted scans and anatomical atlases.

RESULTS

Compared to controls, COVID-CM patients showed overall gray matter atrophy (age and sex corrected p = 0.004), and both COVID-19 patient groups showed regional atrophy and cortical thinning. Both groups presented an increase in gray matter mean diffusivity (corrected p = 0.001), decrease in white matter fiber density and cross-section (corrected p < 0.05), , and COVID-CM patients also displayed an overall increased diffusivity (p = 0.022) and decreased anisotropy (corrected p = 0.038) in white matter. Graph-based analysis revealed reduced network modularity, with an extensive pattern of connectivity increase, in conjunction with a localized reduction in a few connections, mainly located in the left hemisphere. The left cingulate, anterior cingulate, and insula were primarily involved.

CONCLUSION

Expanding upon previous findings, this study further investigated significant alterations in brain morphology, microstructure, and connectivity in COVID-19 patients with olfactory or cognitive disfunction. These findings suggest underlying neurodegeneration, neuroinflammation, and concomitant compensatory mechanisms. Future longitudinal studies are required to monitor the alterations over time and assess their transient or permanent nature.

Olfactory dysfunction as an early predictor for post-COVID condition at 1-year follow-up

BACKGROUND

Olfactory dysfunction together with neurological and cognitive symptoms are common after COVID-19. We aimed to study whether performance on olfactory and neuropsychological tests following infection predict post-COVID condition (PCC), persisting symptoms, and reduced health-related quality of life.

METHODS

Both hospitalized (N = 10) and non-hospitalized individuals (N = 56) were enrolled in this prospective cohort study. Participants were evaluated 1-3 months after infection with an olfactory threshold test and neuropsychological tests, which was used as predictors of PCC. A questionnaire outlining persisting symptoms and the validated instrument EuroQol five-dimension five-level for health-related quality of life assessment were used as outcome data 1 year after infection (N = 59). Principal component analysis was used to identify relevant predictors for PCC at 1 year.

RESULTS

Objectively assessed olfactory dysfunction at 1-3 months post infection, but not subjective olfactory symptoms, predicted post-COVID condition with reduced health-related quality of life (PCC+) at 1 year. The PCC+ group scored more often below the cut off for mild cognitive impairment on the Montreal Cognitive Assessment (61.5% vs. 21.7%) and higher on the Multidimensional Fatigue Inventory-20, compared to the group without PCC+.

CONCLUSION

Our results indicate that objectively assessed, olfactory dysfunction is a predictor for PCC+. These findings underscore the importance of objective olfactory testing. We propose that olfactory screening in the early post-acute phase of COVID-19 infection might identify individuals that are at higher risk of developing long-term health sequalae.

Olfactory immunology: the missing piece in airway and CNS defence

The olfactory mucosa is a component of the nasal airway that mediates the sense of smell. Recent studies point to an important role for the olfactory mucosa as a barrier to both respiratory pathogens and to neuroinvasive pathogens that hijack the olfactory nerve and invade the CNS. In particular, the COVID-19 pandemic has demonstrated that the olfactory mucosa is an integral part of a heterogeneous nasal mucosal barrier critical to upper airway immunity. However, our insufficient knowledge of olfactory mucosal immunity hinders attempts to protect this tissue from infection and other diseases. This Review summarizes the state of olfactory immunology by highlighting the unique immunologically relevant anatomy of the olfactory mucosa, describing what is known of olfactory immune cells, and considering the impact of common infectious diseases and inflammatory disorders at this site. We will offer our perspective on the future of the field and the many unresolved questions pertaining to olfactory immunity.

Recovery rates and long-term olfactory dysfunction following COVID-19 infection

Objectives

Olfactory dysfunction is one of the most recognized symptoms of COVID-19, significantly impacting quality of life, particularly in cases where recovery is prolonged. This review aims to explore patterns of olfactory recovery post-COVID-19 infection, with particular focus on delayed recovery.

Data Sources

Published literature in the English language, including senior author's own work, online and social media platforms, and patients' anecdotal reports.

Method

A comprehensive review of the literature was undertaken by the authors with guidance from the senior author with expertise in the field of olfaction.

Results

Based on self-report, an estimated 95% of patients recover their olfactory function within 6 months post-COVID-19 infection. However, psychophysical testing detects higher rates of persistent olfactory dysfunction. Recovery has been found to continue for at least 2 years postinfection; negative prognostic indicators include severe olfactory loss in the acute phase, female sex, and older age. Variability in quantitative and qualitative disturbance in prolonged cases likely reflects both peripheral and central pathophysiological mechanisms. Limitations of many of the reviewed studies reflect lack of psychophysical testing and baseline olfactory assessment.

Conclusions

Post-COVID-19 olfactory dysfunction remains a significant health and psychosocial burden. Emerging evidence is improving awareness and knowledge among clinicians to better support patients through their olfactory rehabilitation, with hope of recovery after several months or years. Further research is needed to better understand the underlying pathogenesis of delayed recovery, identify at risk individuals earlier in the disease course, and develop therapeutic targets.

Mechanisms by Which SARS-CoV-2 Invades and Damages the Central Nervous System: Apart from the Immune Response and Inflammatory Storm, What Else Do We Know?

Initially reported as pneumonia of unknown origin, COVID-19 is increasingly being recognized for its impact on the nervous system, despite nervous system invasions being extremely rare. As a result, numerous studies have been conducted to elucidate the mechanisms of nervous system damage and propose appropriate coping strategies. This review summarizes the mechanisms by which SARS-CoV-2 invades and damages the central nervous system, with a specific focus on aspects apart from the immune response and inflammatory storm. The latest research findings on these mechanisms are presented, providing new insights for further in-depth research.

Olfactory Sensitivity in Covid 19 Infection Recovered Subjects

Sense of smell is a vital perception in mammals. Temporary loss of smell is the main neurological symptom and one of the earliest and most commonly reported indicators of COVID-19. A observational hospital based analytical study carried out at a tertiary care centre for a period of 22 months from January 2021 to October 2022. All the patients were subjected to sniffin stick test and all the data were noted, tabulated and compared to know the correlation of olfactory sensitivity to different parameters. Males were affected with hyposmia slightly more than females. There was not much difference in the olfactory sensitivity in various phases of uterine cycle. Olfactory sensitivity had a negative correlation with serum oestrogen and serum progesterone levels, which was significant. Mean olfactory sensitivity of males for different odours were slightly higher than females. BMI has a negative correlation with olfactory sensitivity in males as well as females, which was significant.

Olfactory immune response to SARS-CoV-2

Numerous pathogens can infect the olfactory tract, yet the pandemic caused by SARS-CoV-2 has strongly emphasized the importance of the olfactory mucosa as an immune barrier. Situated in the nasal passages, the olfactory mucosa is directly exposed to the environment to sense airborne odorants; however, this also means it can serve as a direct route of entry from the outside world into the brain. As a result, olfactotropic infections can have serious consequences, including dysfunction of the olfactory system, CNS invasion, dissemination to the lower respiratory tract, and transmission between individuals. Recent research has shown that a distinctive immune response is needed to protect this neuronal and mucosal tissue. A better understanding of innate, adaptive, and structural immune barriers in the olfactory mucosa is needed to develop effective therapeutics and vaccines against olfactotropic microbes such as SARS-CoV-2. Here, we summarize the ramifications of SARS-CoV-2 infection of the olfactory mucosa, review the subsequent immune response, and discuss important areas of future research for olfactory immunity to infectious disease.

One-year psychophysical evaluation of COVID-19-induced olfactory disorders: a prospective cohort study

BACKGROUND

Olfactory disorders are common in COVID-19. While many patients recover within weeks, a notable number of patients suffer from prolonged olfactory disorders. Much research has focused on the acute phase of olfactory disorders in COVID-19; however, there is still inconsistency regarding the prognosis. We aim to assess both objective and subjective olfactory function in patients with persisting olfactory disorders following COVID-19, 1 year after diagnosis.

METHODS

We objectively measured olfactory function in 77 patients who initially had COVID-19-induced smell disorders, 1 year after confirmed diagnosis. These patients previously underwent two objective measurements at approximately 3 and 6 months after COVID-19, in the context of the COCOS trial (COrticosteroids for COvid-19-induced loss of Smell). The main outcome measurement was TDI score (threshold-discrimination-identification) on Sniffin' Sticks Test (SST). Secondary outcomes included objective gustatory function on Taste Strip Test (TST), self-reported olfactory, gustatory and trigeminal function on a visual analogue scale (VAS) and outcomes on questionnaires about quality of life, and nasal symptoms.

RESULTS

The findings of this study show that 1 year following COVID-19, the median TDI score increased to 30.75 (IQR 27.38-33.5), regarded as normosmia. The median TDI score started at 21.25 (IQR 18.25-24.75) at baseline and increased to 27.5 (IQR 23.63-30.0) at 6 months following COVID-19. The increase of 9.5 points on the TDI score between baseline and 1 year after COVID-19 marks a clinically relevant improvement. Regarding the self-reported VAS score (1-10) on sense of smell, it increased from 1.2 (IQR 0.4-3.0) at baseline to 3.2 (IQR 1.4-6.0) at 6 months and further improved up to 6.1 (IQR 2.7-7.5) after 1 year. Objective gustatory function increased with 2 points on TST a year after diagnosis. Self-reported olfactory, gustatory, and trigeminal functions also improved over time, as did quality of life.

CONCLUSIONS

Objective and self-reported olfactory function continued to improve 1 year after COVID-19. The median TDI score of 30.75 (IQR 27.38-33.5) is regarded as normosmia, which is a favorable outcome. However, the rate of improvement on TDI score reduces over time.

Olfactory recovery following omicron variant infection: a psychophysical prospective case-control study with six-month follow up

OBJECTIVE

This study aimed to evaluate the recovery of olfactory function at six months in individuals infected with the coronavirus disease 2019 omicron variant, using psychophysical tests.

METHODS

A prospective case-control study that included severe acute respiratory syndrome coronavirus-2 patients infected in February and March 2022 was conducted. Patients underwent the Sniffin' Sticks test within 10 days of infection and again after at least 6 months. The olfactory scores were compared with those of a control group.

RESULTS

In all, 102 patients and 120 controls were enrolled in the study. At baseline, 26 patients (25.5 per cent) self-reported smell loss. The median threshold, discrimination and identification score was 33.6 (interquartile range, 12.5) for the cases and 36.5 (interquartile range, 4.38) for the controls (p < 0.001). Based on the threshold, discrimination and identification scores, 12 controls and 34 patients reported olfactory dysfunction (p < 0.001). Eighty cases underwent re-evaluation at six months; the median threshold, discrimination and identification score was 37.1 (interquartile range, 4.75) with no significant differences compared with the controls.

CONCLUSION

Six months after infection, the prevalence of olfactory dysfunction in patients did not differ significantly from the control population.

Evaluating long-term smell or taste dysfunction in mildly symptomatic COVID-19 patients: a 3-year follow-up study

INTRODUCTION

No studies have reported data on 3-year prevalence and recovery rates of self-reported COVID-19-related olfactory and gustatory dysfunction. The aim of the present study was to estimate the 3-year prevalence and recovery rate of self-reported COVID-19-related chemosensory dysfunction in a cohort of patients with antecedent mild COVID-19.

METHODS

This is a prospective observational study, measuring the prevalence of altered sense of smell or taste at follow-up and their variation from baseline, on adult patients consecutively assessed at Treviso and Trieste University Hospitals, who tested positive for SARS-CoV-2 RNA by polymerase chain reaction during March 2020.

RESULTS

Overall, out of 403 respondents, 267 patients (66.3%) reported an altered sense of smell or taste (SNOT-22 > 0) at baseline, while 56 (13.9%), 29 (7.2%), and 21 (5.2%) reported such alterations at 6-24 months, 2 years, and 3 years, respectively. Among the 267 patients with COVID-19-associated smell or taste dysfunction at baseline, 246 (92.1%) reported complete resolution at 3 years. Of the patients who still experienced smell or taste dysfunction 2 years after COVID-19, 27.6% and 37.9% recovered completely and partially, respectively, at the 3-year follow-up.

CONCLUSION

Among subjects with antecedent mildly symptomatic SARS-CoV-2 infection, the 3-year prevalence and recovery rate of COVID-19-related alteration in sense of smell or taste was 5% and 92%, respectively. In approximately two-thirds of patients experiencing chemosensory dysfunction still 2 years after COVID-19, it is still possible to observe a delayed complete or partial recovery after a period of 3 years, while the remaining one-third of individuals continues to have unchanged persistent chemosensory alteration.

Mechanism and treatment of olfactory dysfunction caused by coronavirus disease 2019

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the start of the pandemic, olfactory dysfunction (OD) has been reported as a common symptom of COVID-19. In some asymptomatic carriers, OD is often the first and even the only symptom. At the same time, persistent OD is also a long-term sequela seen after COVID-19 that can have a serious impact on the quality of life of patients. However, the pathogenesis of post-COVID-19 OD is still unclear, and there is no specific treatment for its patients. The aim of this paper was to review the research on OD caused by SARS-CoV-2 infection and to summarize the mechanism of action, the pathogenesis, and current treatments.

Distinct smell and taste disorder phenotype of post-acute COVID-19 sequelae

PURPOSE

Olfactory dysfunction (OD) commonly accompanies coronavirus disease 2019 (COVID-19). We investigated the kinetics of OD resolution following SARS-CoV-2 infection (wild-type and alpha variant) and its impact on quality of life, physical and mental health.

METHODS

OD prevalence was assessed in an ambulatory COVID-19 survey (n = 906, ≥ 90 days follow-up) and an observational cohort of ambulatory and hospitalized individuals (n = 108, 360 days follow-up). Co-occurrence of OD with other symptoms and effects on quality of life, physical and mental health were analyzed by multi-dimensional scaling, association rule mining and semi-supervised clustering.

RESULTS

Both in the ambulatory COVID-19 survey study (72%) and the observational ambulatory and hospitalized cohort (41%) self-reported OD was frequent during acute COVID-19. Recovery from self-reported OD was slow (survey: median 28 days, observational cohort: 90 days). By clustering of the survey data, we identified a predominantly young, female, comorbidity-free group of convalescents with persistent OD and taste disorders (median recovery: 90 days) but low frequency of post-acute fatigue, respiratory or neurocognitive symptoms. This smell and taste disorder cluster was characterized by a high rating of physical performance, mental health, and quality of life as compared with convalescents affected by prolonged fatigue or neurocognitive complaints.

CONCLUSION

Our results underline the heterogeneity of post-acute COVID-19 sequelae calling for tailored management strategies. The persistent smell and taste disorder phenotype is characterized by good clinical, physical, and mental recovery and may pose a minor challenge for public health.

STUDY REGISTRATION

ClinicalTrials.gov: NCT04661462 (survey study), NCT04416100 (observational cohort).

Olfactory and gustatory dysfunction, evaluation and the impact on quality of life among COVID-19 patients: a multi-centre study

Background

Olfactory and gustatory dysfunctions are frequently reported symptoms among COVID-19 patients. However, several reports suggested that there might be significant variation in the prevalence and clinical picture of chemosensory dysfunction in COVID-19 patients among different population.

Objective

To study the prevalence of chemosensory dysfunction, recovery time and its impact on quality of life (QoL) among COVID-19 patients in Saudi population.

Methods

This multi-centre observational study was conducted at three COVID-19 centres in Saudi Arabia. Epidemiological and clinical data were extracted at baseline and within the 2-month post-infection. Olfactory and gustatory dysfunctions were assessed via valid taste and smell questionnaire, electronically collected via online survey. Short version of questionnaire of Olfactory disorders-negative statements (sQOD-NS) was used to assess the impact on QoL.

Result

Total 1734 patients [926 males and 808 females, the mean age of patients was 37.7±11.6 years] with laboratory confirmed COVID-19 were recruited for this study. Chemosensory dysfunction was reported in 56.5% cases. olfactory and gustatory dysfunctions were significantly high in females (66.2%) and age group younger than or equal to 40 years (62.2%). Among patients with olfactory dysfunction and gustatory dysfunction, recovery rate was 757 (77.2%) and 702 (71.6%). Furthermore, the recovery time was within 8 days of onset of symptoms in 53.6% and 61.3% of olfactory dysfunction and gustatory dysfunction cases, respectively. Overall mean QoL score indicated Olfactory and gustatory dysfunction has significant impact on QoL [11.3±6.2 (P value<0.001)]. female as compared to males (12.8±7). Females had significant impact on QoL (11.4±6.6) as compared to males [12.8±7 (P value<0.001)].

Conclusion

Chemosensory dysfunction among Saudi population was comparable to the European data and significantly higher than Asian supporting the fact that these symptoms vary as per ethnicity. Olfactory and gustatory dysfunction significantly impaired QoL and could present as an early symptom of COVID-19. Recovery rate of these symptoms can serve as a good prognostic data for patient's counselling. Further long-term follow-up studies would lead to better understanding of prognosis and clinical outcomes.

Psychophysical assessment of olfactory and gustatory function in post-mild COVID-19 patients: A matched case-control study with 2-year follow-up

BACKGROUND

The aim of this study was to psychophysically evaluate the prevalence of smell and taste dysfunction 2 years after mildly symptomatic severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection compared to that observed at 1-year follow-up and while considering the background of chemosensory dysfunction in the no-coronavirus disease 2019 (COVID-19) population.

METHOD

This is a prospective case-control study on 93 patients with polymerase chain reaction (PCR)-positive SARS-CoV-2 infection and 93 matched controls. Self-reported olfactory and gustatory dysfunction was assessed by 22-item Sino-Nasal-Outcome Test (SNOT-22), item "Sense of smell or taste." Psychophysical orthonasal and retronasal olfactory function and gustatory performance were estimated using the extended Sniffin' Sticks test battery, 20 powdered tasteless aromas, and taste strips test, respectively. Nasal trigeminal sensitivity was assessed by sniffing a 70% solution of acetic acid.

RESULTS

The two psychophysical assessments of chemosensory function took place after a median of 409 days (range, 366-461 days) and 765 days (range, 739-800 days) from the first SARS-CoV-2-positive swab, respectively. At 2-year follow-up, cases exhibited a decrease in the prevalence of olfactory (27.9% vs. 42.0%; absolute difference, -14.0%; 95% confidence interval [CI], -21.8% to -2.6%; p = 0.016) and gustatory dysfunction (14.0% vs. 25.8%; absolute difference, -11.8%; 95% CI, -24.2% to 0.6%; p = 0.098). Subjects with prior COVID-19 were more likely than controls to have an olfactory dysfunction (27.9% vs. 10.8 %; absolute difference, 17.2%; 95% CI, 5.2% to 28.8%) but not gustatory dysfunction (14.0% vs. 9.7%; absolute difference, 4.3%; 95% CI, -5.8% to 14.4% p = 0.496) still 2 years after the infection. Overall, 3.2% of cases were still anosmic 2 years after the infection.

CONCLUSIONS

Although a proportion of subjects recovered from long-lasting smell/taste dysfunction more than 1 year after COVID-19, cases still exhibited a significant excess of olfactory dysfunction 2 years after SARS-CoV-2 infection when compared to matched controls.

Persistent post-COVID-19 dysosmia: Practices survey of members of the French National Union of Otorhinolaryngology-Head and Neck Surgery Specialists. CROSS analysis

INTRODUCTION

Persistent dysosmia more than 3 months after SARS-CoV-2 disease (COVID-19) is considered as long-COVID olfactory disease (LCOD). The primary objective of this study was to evaluate the diagnostic and therapeutic management of LCOD in the daily clinical practice of members of the National Union of Otorhinolaryngology-Head and Neck Surgery Specialists (Syndicat national des médecins spécialisés en ORL et chirurgie cervico-faciale) (SNORL). The secondary objective was to identify factors influencing management within the descriptive survey data.

MATERIALS AND METHODS

A questionnaire was designed (GoogleForm®) and e-mailed to all 715 SNORL members in January 2022.

RESULTS

The response rate was 7.4% (n=53/715). In total, 94.3% of respondents (n=50) had managed LCOD cases, and 56% (n=28) used psychophysical olfactory tests. Specific olfactory medical therapy involved local corticosteroid nasal sprays in 49.1% of cases (n=26) and oral corticosteroids in 32.1% (n=17). Olfactory self-training was prescribed by 81.1% of respondents, with associated speech pathologist therapy in 15.1% (n=8) of cases. No predictive factors for specific management were identified.

CONCLUSION

Olfactometry is currently under-applied. Consistent with guidelines, non-drug therapy (olfactory training) is the first-line treatment for LCOD.

Alzheimer's early detection in post-acute COVID-19 syndrome: a systematic review and expert consensus on preclinical assessments

Introduction

The risk of developing Alzheimer's disease (AD) in older adults increasingly is being discussed in the literature on Post-Acute COVID-19 Syndrome (PACS). Remote digital Assessments for Preclinical AD (RAPAs) are becoming more important in screening for early AD, and should always be available for PACS patients, especially for patients at risk of AD. This systematic review examines the potential for using RAPA to identify impairments in PACS patients, scrutinizes the supporting evidence, and describes the recommendations of experts regarding their use.

Methods

We conducted a thorough search using the PubMed and Embase databases. Systematic reviews (with or without meta-analysis), narrative reviews, and observational studies that assessed patients with PACS on specific RAPAs were included. The RAPAs that were identified looked for impairments in olfactory, eye-tracking, graphical, speech and language, central auditory, or spatial navigation abilities. The recommendations' final grades were determined by evaluating the strength of the evidence and by having a consensus discussion about the results of the Delphi rounds among an international Delphi consensus panel called IMPACT, sponsored by the French National Research Agency. The consensus panel included 11 international experts from France, Switzerland, and Canada.

Results

Based on the available evidence, olfaction is the most long-lasting impairment found in PACS patients. However, while olfaction is the most prevalent impairment, expert consensus statements recommend that AD olfactory screening should not be used on patients with a history of PACS at this point in time. Experts recommend that olfactory screenings can only be recommended once those under study have reported full recovery. This is particularly important for the deployment of the olfactory identification subdimension. The expert assessment that more long-term studies are needed after a period of full recovery, suggests that this consensus statement requires an update in a few years.

Conclusion

Based on available evidence, olfaction could be long-lasting in PACS patients. However, according to expert consensus statements, AD olfactory screening is not recommended for patients with a history of PACS until complete recovery has been confirmed in the literature, particularly for the identification sub-dimension. This consensus statement may require an update in a few years.

The assessment of qualitative olfactory dysfunction in COVID-19 patients: a systematic review of tools and their content validity

Background

There is a lack of overview of the tools used to assess qualitative olfactory dysfunction, including parosmia and phantosmia, following COVID-19 illness. This could have an impact on the diagnosis and treatment offered to patients. Additionally, the formulations of symptoms are inconsistent and often unclear, and consensus around the wording of questions and responses is needed.

Aim of study

The aim of this systematic review is to provide an overview of tools used to assess qualitative olfactory dysfunction after COVID-19, in addition to addressing the content validity (i.e., item and response formulations) of these tools.

Methods

MEDLINE, Web of Science, and EMBASE were searched 5th of August 2022 and updated on the 25th of April 2023 to identify studies that assess qualitative olfactory dysfunction in COVID-19 patients. Primary outcomes were the tool used (i.e., questionnaire or objective test) and item and response formulations. Secondary outcomes included psychometric properties, study design, and demographic variables.

Results

The assessment of qualitative olfactory dysfunction is characterized by heterogeneity, inconsistency, and lack of validated tools to determine the presence and degree of symptoms. Several tools with overlapping and distinct features were identified in this review, of which some were thorough and detailed, while others were merely assessing the presence of symptoms as a binary measure. Item and response formulations are also inconsistent and often used interchangeably, which may lead to confusion, incorrect diagnoses, and inappropriate methods for solving the problem.

Conclusions

There is an unmet need for a reliable and validated tool for assessing qualitative olfactory dysfunction, preferably one that also captures quantitative olfactory issues (i.e., loss of smell), to ensure time-effective and specific assessment of the ability to smell. A consensus around the formulation of items and response options is also important to increase the understanding of the problem, both for clinicians, researchers, and the patient, and ultimately to provide the appropriate diagnosis and treatment.

Registration and protocol

The URL is https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=351621. A preregistered protocol was submitted and accepted (12.09.22) in the International prospective register of systematic reviews (PROSPERO) with the registration number CRD42022351621.

Evaluation of children and adults with post-COVID-19 persistent smell, taste and trigeminal chemosensory disorders: A hospital based study

BACKGROUND

Smell disorders are the most frequent persistent coronavirus disease 2019 (COVID-19) complications.

AIM

To describe the patterns and characteristics of persistent smell and taste disorders in Egyptian patients.

METHODS

Assessment was done to 185 patients (adults = 150, age: 31.41 ± 8.63 years; children = 35; age: 15.66 ± 1.63 years). Otolaryngology and neuropsychiatric evaluations were done. Measurements included: A clinical questionnaire (for smell and taste); sniffin' odor, taste and flavor identification tests and the Questionnaire of Olfactory Disorders-Negative Statements (sQOD-NS).

RESULTS

Duration of disorders was 11.53 ± 3.97 ms (6-24 ms). Parosmia (n = 119; 64.32%) was developed months after anosmia (3.05 ± 1.87 ms). Objective testing showed anosmia in all, ageusia and flavor loss in 20% (n = 37) and loss of nasal and oral trigeminal sensations in 18% (n = 33) and 20% (n = 37), respectively. Patients had low scoring of sQOD-NS (11.41 ± 3.66). There were no specific differences in other demographics and clinical variables which could distinguish post-COVID-19 smell and taste disorders in children from adults.

CONCLUSION

The course of small and taste disorders are supportive of the nasal and oral neuronal compromises. Post-COVID-19 taste and trigeminal disorders were less frequent compared to smell disorders. Post-COVID-19 flavor disorders were solely dependent on taste and not smell disorders. There were no demographics, clinical variables at onset or specific profile of these disorders in children compared to adults.

Post-COVID-19 persistent olfactory, gustatory, and trigeminal chemosensory disorders: Definitions, mechanisms, and potential treatments

The nose and the oral cavities are the main sites for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry into the body. Smell and taste deficits are the most common acute viral manifestations. Persistent smell disorders are the most common and bothersome complications after SARS-CoV-2 infection, lasting for months to years. The mechanisms and treatment of persistent post-coronavirus disease 2019 (COVID-19) smell and taste disorders are still challenges. Information sources for the review are PubMed, Centers for Disease Control and Prevention, Ovid Medline, Embase, Scopus, Web of Science, International Prospective Register of Systematic Reviews, Cumulative Index to Nursing and Allied Health Literature, Elton Bryson Stephens Company, Cochrane Effective Practice and Organization of Care, Cooperation in Science and Technology, International Clinical Trials Registry Platform, World Health Organization, Randomized Controlled Trial Number Registry, and MediFind. This review summarizes the up-to-date information about the prevalence, patterns at onset, and prognoses of post-COVID-19 smell and taste disorders, evidence for the neurotropism of SARS-CoV-2 and the overlap between SARS-CoV-1, Middle East respiratory syndrome coronavirus, and SARS-CoV-2 in structure, molecular biology, mode of replication, and host pathogenicity, the suggested cellular and molecular mechanisms for these post-COVID19 chemosensory disorders, and the applied pharmacotherapies and interventions as trials to treat these disorders, and the recommendations for future research to improve understanding of predictors and mechanisms of these disorders. These are crucial for hopeful proper treatment strategies.

Parosmia COVID-19 Related Treated by a Combination of Olfactory Training and Ultramicronized PEA-LUT: A Prospective Randomized Controlled Trial

During COVID-19 pandemic, clinicians have had to deal with an ever-increasing number of cases of olfactory disturbances after SARS-CoV-2 infections and in some people this problem persisted for long time after negativization from virus. This a prospective randomized controlled trial aims at evaluating the efficacy of ultramicronized palmitoylethanolamide (PEA) and Luteolin (LUT) (umPEA-LUT) and olfactory training (OT) compared to OT alone for the treatment of smell disorders in Italian post-COVID population. We included patients with smell loss and parosmia who were randomized and assigned to Group 1 (intervention group; daily treatment with umPEA-LUT oral supplement and OT) or Group 2 (control group; daily treatment with placebo and OT). All subjects were treated for 90 consecutive days. The Sniffin’ Sticks identification test was used to assess the olfactory functions at the baseline (T0) and the end of the treatment (T1). Patients were queried regarding any perception of altered olfaction (parosmia) or aversive smell, such as cacosmia, gasoline-type smell, or otherwise at the same observational points. This study confirmed the efficacy of combination of umPEA-LUT and olfactory training as treatment of quantitative smell alteration COVID-19 related, but the efficacy of the supplement for parosmia was limited. UmpEA-LUT is useful for the treatment of brain neuro-inflammation (origin of quantity smell disorders) but has limited/no effect on peripheral damage (olfactory nerve, neuro-epithelium) that is responsible of quality disorders.

Comparison of prevalence and evolution of COVID-19 olfactory disorders in patients infected by D614 (wild) and B.1.1.7. Alpha variant: a brief report

OBJECTIVES

To investigate the prevalence and the evolution of olfactory disorders (OD) related to coronavirus disease 2019 (COVID-19) in patients infected during the first and the second European waves.

METHODS

From March 2020 to October 2020, COVID-19 patients with OD were recruited and followed over the 12-month post-infection. The following data were collected: demographic, treatments, vaccination status, and olfactory function. Olfaction was assessed with the Olfactory Disorder Questionnaire (ODQ), and threshold, discrimination, and identification (TDI) test. Outcomes were compared between patients of the first wave (group 1: wild/D614G virus) and the second wave (group 2: B.1.1.7. Alpha variant) at 1-, 3- and 12-month post-infection.

RESULTS

Sixty patients completed the evaluations accounting for 33 and 27 patients in group 1 and 2, respectively. The 1-month TDI score (23.7 ± 5.3) was significantly lower in group 2 compared to group 1 (29.8 ± 8.7; p = 0.017). Proportion of normosmic patients at 1-month post-infection was significantly higher in group 1 compared to group 2 (p = 0.009). TDI scores only significantly increased from 1- to 3-month post-infection in anosmic and hyposmic patients. Focusing on There was a negative association between the 1-month ODQ and the 1-month TDI (r_s = - 0.493; p = 0.012). ODQ was a significant predictor of TDI scores at 3- and 12-month post-infection. The 12-month prevalence of parosmia was 60.6% in group 1 and 42.4% in group 2, respectively. There was no significant influence of oral corticosteroid treatment, adherence to an olfactory training and vaccination status on the olfactory outcomes.

CONCLUSIONS

Patients of the second wave (Alpha B.1.1.7. variant) reported significant higher proportion of psychophysical test abnormalities at 1-month post-infection than patients infected during the first wave (D614G virus).

Therapies for COVID-19-Related Persistent Olfactory Disorders: One of the Good Fruits of the Pandemic

At the beginning of 2021, the scientific community realized the burden of COVID-19-related persistent olfactory disorders (ODs). The percentage of those infected with COVID-19 who developed severe and persistent ODs [1-3] with devastating effects on their quality of life was 5 to 40% [4,5].

Parosmia and Phantosmia: Managing Quality Disorders

Purpose of Review

The purpose of this review was to summarize the current knowledge on parosmia and phantosmia and introduce support and treatment algorithms for the two qualitative olfactory disorders.

Recent Findings

Recent literature regarding parosmia has revealed that patients with the disorder are mainly triggered by certain substances, including thiols and pyrazines. In 2015, the existing "olfactory training" regimen was improved to more effectively treat post-infectious olfactory loss and was named "modified olfactory training" (MOT). It was also found in 2022 that MOT is also effective against COVID-19-induced parosmia.

Summary

Parosmia, the distortion of smells, is a symptom in qualitative olfactory disorders that severely affects patients' mental well-being and enjoyment of their everyday lives. The condition was first documented in 1895 and can affect up to 5% of the general population. Etiologies of parosmia include sinonasal diseases, viruses, surgeries, traumatic brain injury, neurological and psychiatric conditions, toxic chemicals, and medications. Parosmia has seen a surge in cases since the onset of the COVID-19 pandemic and is linked to changes in brain structure following an infection. The evaluation of the symptom is done using surveys, smell identification tests, fMRI, MRI, PET/CT, and gas chromatography. Treatment for parosmia can vary in duration, which makes it essential to focus not only on helping the patients regain normosmia, but also on supporting the patient through the recovery journey. Parosmia should not be confused with phantosmia, in which the distortion of smells occurs in the absence of olfactory stimuli. The etiology of phantosmia can vary from infections and traumatic brain injury to psychiatric disorders like schizophrenia. Unlike parosmia, the treatment of phantosmia is less straightforward, with an emphasis on determining the etiology and providing symptomatic relief.

The Trajectories of Olfactory Dysfunction from the First to the Omicron Wave: Are We Getting over it?

It has now been two years since the publication in Pathogens of our European multicenter study on the prevalence of olfactory dysfunctions (OD) during COVID-19 [...].

Post-Viral Olfactory Loss: What We Learned from the SARS-CoV-2 Pandemic

Viral infections have always been one of the most frequent causes of persistent olfactory dysfunctions accounting for 18% to 45% of all cases [...].

Two-Year Follow-Up on Chemosensory Dysfunction and Adaptive Immune Response after Infection with SARS-CoV-2 in a Cohort of 44 Healthcare Workers

Persistent chemosensory dysfunction (PCD) is a common symptom of long-COVID. Chemosensory dysfunction (CD) as well as SARS-CoV-2-specific antibody levels and CD8⁺ T-cell immunity were investigated in a cohort of 44 healthcare workers up to a median of 721 days after a positive PCR test. CD was assessed using questionnaires and psychophysical screening tests. After 721 days, 11 of 44 (25%) participants reported PCD, with five describing an impaired quality of life. One participant reported hyperosmia (increased sense of smell). The risk of PCD at 721 days was higher for participants reporting qualitative changes (parosmia (altered smell), dysgeusia (altered taste), or phantosmia (hallucination of smell)) during initial infection than in those with isolated quantitative losses during the first COVID-19 infection (62.5% vs. 7.1%). The main recovery rate occurred within the first 100 days and did not continue until follow-up at 2 years. No correlation was found between antibody levels and CD, but we observed a trend of a higher percentage of T-cell responders in participants with CD. In conclusion, a significant proportion of patients suffer from PCD and impaired quality of life 2 years after initial infection. Qualitative changes in smell or taste during COVID-19 pose a higher risk for PCD.