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Oral Diseases Nov 2022The COVID-19 pandemic caused by SARS-CoV-2 virus quickly spread globally, infecting over half a billion individuals, and killing over 6 million*. One of the more unusual... (Review)
Review
The COVID-19 pandemic caused by SARS-CoV-2 virus quickly spread globally, infecting over half a billion individuals, and killing over 6 million*. One of the more unusual symptoms was patients' complaints of sudden loss of smell and/or taste, a symptom that has become more apparent as the virus mutated into different variants. Anosmia and ageusia, the loss of smell and taste, respectively, seem to be transient for some individuals, but for others persists even after recovery from the infection. Causes for COVID-19-associated chemosensory loss have undergone several hypotheses. These include non-functional or destroyed olfactory neurons and gustatory receptors or of their supporting cells, disruption of the signaling protein Neuropilin-1, and disruption in the interaction with semaphorins, key molecules in the gustatory and olfactory axon guidance. The current paper will review these hypotheses and chart out potential therapeutic avenues.
Topics: Humans; COVID-19; Pandemics; SARS-CoV-2; Taste Disorders; Olfaction Disorders; Anosmia
PubMed: 35790059
DOI: 10.1111/odi.14300 -
Chemical Senses Jan 2021Among those many individuals who experience a reduced odor sensitivity (hyposmia/anosmia), some individuals also have disorders that lead to odor distortion, such as...
Among those many individuals who experience a reduced odor sensitivity (hyposmia/anosmia), some individuals also have disorders that lead to odor distortion, such as parosmia (i.e. distorted odor with a known source), or odor phantoms (i.e. odor sensation without an odor source). We surveyed a large population with at least one olfactory disorder (N = 2031) and found that odor distortions were common (46%), with respondents reporting either parosmia (19%), phantosmia (11%), or both (16%). In comparison to respondents with hyposmia or anosmia, respondents with parosmia were more likely to be female, young, and suffering from post-viral olfactory loss (P < 0.001), while respondents with phantosmia were more likely to be middle-aged (P < 0.01) and experiencing symptoms caused by head trauma (P < 0.01). In addition, parosmia, compared to phantosmia or anosmia/hyposmia, was most prevalent 3 months to a year after olfactory symptom onset (P < 0.001), which coincides with the timeline of physiological recovery. Finally, we observed that the frequency and duration of distortions negatively affects the quality of life, with parosmia showing a higher range of severity than phantosmia (P < 0.001). Previous research often grouped these distortions together, but our results show that they have distinct patterns of demographics, medical history, and loss in quality of life.
Topics: Female; Humans; Male; Middle Aged; Odorants; Olfaction Disorders; Prevalence; Quality of Life; Smell
PubMed: 34698820
DOI: 10.1093/chemse/bjab046 -
Ugeskrift For Laeger Feb 2023Change in olfactory and/or gustatory dysfunction have gained attention in recent years because of COVID-19. However, these symptoms are common and have numerous... (Review)
Review
Change in olfactory and/or gustatory dysfunction have gained attention in recent years because of COVID-19. However, these symptoms are common and have numerous different aetiologies, which should not be forgotten. Adequate diagnostic work up and clinical examination is essential. Treatment may include olfactory training, topically applied steroids and perhaps surgery. This review summarises common reversible causes of olfactory and/or gustatory dysfunction and current treatment modalities.
Topics: Humans; COVID-19; SARS-CoV-2; Olfaction Disorders; Smell; Taste Disorders
PubMed: 36892317
DOI: No ID Found -
Chemical Senses Sep 2017Anosmia and hyposmia, the inability or decreased ability to smell, is estimated to afflict 3-20% of the population. Risk of olfactory dysfunction increases with old age... (Review)
Review
Anosmia and hyposmia, the inability or decreased ability to smell, is estimated to afflict 3-20% of the population. Risk of olfactory dysfunction increases with old age and may also result from chronic sinonasal diseases, severe head trauma, and upper respiratory infections, or neurodegenerative diseases. These disorders impair the ability to sense warning odors in foods and the environment, as well as hinder the quality of life related to social interactions, eating, and feelings of well-being. This article reports and extends on a clinical update commencing at the 2016 Association for Chemoreception Sciences annual meeting. Included were reports from: a patient perspective on losing the sense of smell with information on Fifth Sense, a nonprofit advocacy organization for patients with olfactory disorders; an otolaryngologist's review of clinical evaluation, diagnosis, and management/treatment of anosmia; and researchers' review of recent advances in potential anosmia treatments from fundamental science, in animal, cellular, or genetic models. As limited evidence-based treatments exist for anosmia, dissemination of information on anosmia-related health risks is needed. This could include feasible and useful screening measures for olfactory dysfunction, appropriate clinical evaluation, and patient counseling to avoid harm as well as manage health and quality of life with anosmia.
Topics: Delivery of Health Care; Humans; Neuronal Plasticity; Olfaction Disorders; Prognosis; Quality of Life; Smell; Stem Cell Transplantation
PubMed: 28531300
DOI: 10.1093/chemse/bjx025 -
Science Translational Medicine Dec 2022SARS-CoV-2 causes profound changes in the sense of smell, including total smell loss. Although these alterations are often transient, many patients with COVID-19 exhibit...
SARS-CoV-2 causes profound changes in the sense of smell, including total smell loss. Although these alterations are often transient, many patients with COVID-19 exhibit olfactory dysfunction that lasts months to years. Although animal and human autopsy studies have suggested mechanisms driving acute anosmia, it remains unclear how SARS-CoV-2 causes persistent smell loss in a subset of patients. To address this question, we analyzed olfactory epithelial samples collected from 24 biopsies, including from nine patients with objectively quantified long-term smell loss after COVID-19. This biopsy-based approach revealed a diffuse infiltrate of T cells expressing interferon-γ and a shift in myeloid cell population composition, including enrichment of CD207 dendritic cells and depletion of anti-inflammatory M2 macrophages. Despite the absence of detectable SARS-CoV-2 RNA or protein, gene expression in the barrier supporting cells of the olfactory epithelium, termed sustentacular cells, appeared to reflect a response to ongoing inflammatory signaling, which was accompanied by a reduction in the number of olfactory sensory neurons relative to olfactory epithelial sustentacular cells. These findings indicate that T cell-mediated inflammation persists in the olfactory epithelium long after SARS-CoV-2 has been eliminated from the tissue, suggesting a mechanism for long-term post-COVID-19 smell loss.
Topics: Animals; Humans; COVID-19; Anosmia; SARS-CoV-2; RNA, Viral; Olfaction Disorders; Olfactory Mucosa; Gene Expression
PubMed: 36542694
DOI: 10.1126/scitranslmed.add0484 -
International Forum of Allergy &... Nov 2020
Topics: Humans; Odorants; Olfaction Disorders; Olfactory Bulb; Smell
PubMed: 32776673
DOI: 10.1002/alr.22681 -
Cell and Tissue Research Jan 2021The sense of smell essentially contributes to social communication, guides nutrition behaviour and elicits avoidance towards environmental hazards. Olfactory smell... (Review)
Review
The sense of smell essentially contributes to social communication, guides nutrition behaviour and elicits avoidance towards environmental hazards. Olfactory smell impairment may hence entail severe consequences for affected individuals. Compared with sensory loss in other modalities, reduced olfactory function is often unnoticed by those affected and diagnosed late. Those patients seeking help frequently suffer from long-term impairments resulting in reduced well-being and quality of life. The current review provides an overview of aetiology, prevalence and specifics of diagnostics in acquired and congenital olfactory loss and focusses on short- and long-term consequences. Compensation strategies are elaborated, and treatment options are mentioned. Individual characteristics associated with the development of serious mental health impairment are discussed in order to help practitioners identifying populations at risk.
Topics: Humans; Olfaction Disorders
PubMed: 33496882
DOI: 10.1007/s00441-020-03381-9 -
Journal of Huntington's Disease 2021Olfactory dysfunction is a common symptom in patients with neurodegenerative disorders, including Huntington's disease (HD). Understanding its pathophysiology is... (Review)
Review
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.
Topics: Humans; Huntington Disease; Neurodegenerative Diseases; Olfaction Disorders; Smell
PubMed: 34719504
DOI: 10.3233/JHD-210497 -
Current Opinion in Otolaryngology &... Feb 2022This article reviews the literature on COVID-19 related anosmia, focusing on the epidemiology, pathophysiology recovery rates, current available treatment options, and... (Review)
Review
PURPOSE OF REVIEW
This article reviews the literature on COVID-19 related anosmia, focusing on the epidemiology, pathophysiology recovery rates, current available treatment options, and research regarding novel treatments.
RECENT FINDINGS
Loss of sense of smell is one of the most prevalent symptoms reported by patients after COVID-19 infection. Even though there is a high self-reported recovery rate, recent studies have demonstrated that up to 7% of the patients remain anosmic more than 12 months after onset, leaving millions worldwide with severe olfactory dysfunction. Olfactory training remains the first line recommended treatment. Given the paucity of effective medical treatments options researchers are exploring novel therapeutic options.
SUMMARY
Olfactory dysfunction remains a significant and persistent legacy of the COVID-19 pandemic, but heightened awareness may stimulate research that leads to the development of much-needed treatment options.
Topics: COVID-19; Humans; Olfaction Disorders; Pandemics; SARS-CoV-2; Smell
PubMed: 34889850
DOI: 10.1097/MOO.0000000000000783 -
Journal of Investigational Allergology... 2020The first cases of coronavirus 2019 disease (COVID-19) occurred in Wuhan, China, and the disease rapidly become a public health emergency of international proportions.... (Review)
Review
The first cases of coronavirus 2019 disease (COVID-19) occurred in Wuhan, China, and the disease rapidly become a public health emergency of international proportions. COVID-19 can cause mild-to-severe acute respiratory syndrome (SARS) and is caused by the SARS-CoV-2 coronavirus. The clinical manifestations of COVID-19 include fever, dry cough, fatigue, sputum production, shortness of breath, sore throat, and headache. We performed this narrative review to analyze the current literature on postviral olfactory dysfunction related to the SARSCoV- 2 pandemic. Since the initial anecdotal reports from China, increasingly frequent international reports on COVID-19 indicate that 5% to 85% of affected patients lose their sense of smell, thus highlighting the very heterogeneous nature of the literature in this area. Therefore, we advise home isolation measures and/or social distancing, as well as tests to detect SARS-CoV-2 when possible, in patients with sudden and severe loss of smell who cannot be promptly evaluated.
Topics: Betacoronavirus; COVID-19; Coronavirus Infections; Disease Outbreaks; Female; Humans; Male; Olfaction Disorders; Olfactory Bulb; Pandemics; Pneumonia, Viral; SARS-CoV-2; Smell
PubMed: 32406374
DOI: 10.18176/jiaci.0567