What Is Anosmia?

COVID-19 and anosmia: The story so far

OBJECTIVES

The pandemic has affected over 182 million coronavirus disease 2019 (COVID-19) cases worldwide. Accumulated evidence indicates that anosmia is one of the significant characteristics of COVID-19 with a high prevalence. However, many aspects of COVID-19-induced anosmia are still far from being fully understood. The purpose of this review is to summarize recent developments in COVID-19-induced anosmia to increase awareness of the condition.

METHODS

A literature search was carried out using the PubMed, Embase, Web of Science, and Scopus. We reviewed the latest literature on COVID-19-induced anosmia, including mechanisms of pathogenesis, olfactory testing, anosmia as predictive tool, pathological examinations, imaging findings, affected factors, co-existing diseases, treatments, prognosis, hypothesis theories, and future directions.

RESULTS

The possible pathogenesis of COVID-19-induced anosmia may involve inflammation of the olfactory clefts and damage to the olfactory epithelium or olfactory central nervous system by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The D614G spike variant may also play a role in the increased number of anosmia patients. Anosmia may also be an essential indicator of COVID-19 spread and an early indicator of the effectiveness of political decisions. The occurrence and development of COVID-19-induced anosmia may be influenced by smoking behaviors and underlying diseases such as type 2 diabetes, gastroesophageal disorders, and rhinitis. Most patients with COVID-19-induced anosmia can fully or partially recover their olfactory function for varying durations. COVID-19-induced anosmia can be treated with various approaches such as glucocorticoids and olfactory training.

CONCLUSION

Anosmia is one of the main features of COVID-19 and the underlying disease of the patient may also influence its occurrence and development. The possible pathogenesis of COVID-19-induced anosmia is very complicated, which may involve inflammation of the olfactory clefts and damage to the olfactory epithelium or olfactory central nervous system.

Transient Anosmia and Dysgeusia in COVID-19 Disease: A Cross Sectional Study

Objective

This study aims to explore the prevalence of anosmia and dysgeusia and their impact on COVID-19 patients.

Methods

This is a cross-sectional study. Patients diagnosed with COVID-19 between 1st October 2020 and 30th June 2021 were randomly selected from a national COVID-19 registry. COVID-19 cases were diagnosed using molecular testing method which measured the viral E gene. The Anosmia Reporting Tool, and a brief version of the questionnaire on olfactory disorders were used to measure the outcomes via telephone interviews. Data were analysed using SPSS 27 statistics software.

Results

A total of 405 COVID-19 adults were included in this study, 220 (54.3%) were males and 185 (45.8%) were females. The mean±SD age of participants was 38.2 ± 11.3 years. Alterations in the sense of smell and taste were reported by 206 (50.9%), and 195 (48.1%) of the patients, respectively. Sex and nationality of participants were significantly associated with anosmia and dysgeusia (p < 0.001) and (p-value=0.001) respectively. Among patients who experienced anosmia and dysgeusia, alterations in eating habits (64.2%), impact on mental wellbeing (38.9%), concerns that the alterations were permanent (35.4%), and physical implications and difficulty performing activities of daily living (34%) were reported.

Conclusion

Anosmia and dysgeusia are prevalent symptoms of COVID-19 disease, especially among females. Although transient, anosmia and dysgeusia had considerable impact on patient's life. Neuropsychological implications of COVID-19 in acute infection phase and prognosis of anosmia and dysgeusia in COVID-19 are areas for further exploration.

Whole-Body Cryotherapy as an Innovative Treatment for COVID 19-Induced Anosmia-Hyposmia: A Feasibility Study

The article entitled, "Whole-Body Cryotherapy as an Innovative Treatment for COVID 19-Induced Anosmia-Hyposmia: A Feasibility Study," by Legrand FD, Polidori G, Beaumont F, Bouchet B, Morin A, Derruau S, and Brenet E (Epub ahead of print Jan 13, 2022; DOI: 10.1089/jicm.2021.0254) is officially retracted at the request of the authors. This request came after the paper had undergone full peer review, three rounds of revisions, acceptance, page proofs, and ultimately, online publication. The Methods section of the published paper states that the study had "secured University ethics clearance…"¹ but the authors explained that, "after re-discussion and internal reassessment, it appears clearly that this study required, according to French law, the approval of a specific committee known as the '[C]ommittee for the [P]rotection of [P]ersons (CPP)' and not a simple ethical agreement. For this reason, [we] request, in good faith, that the article be retracted. We apologize for this delay in taking a position, but this study gave rise to a re-discussion with our peers of the methodology which led us to realize our error 'a posteriori.'" The authors' respective institutions have been notified by the publisher. Journal of Integrative and Complementary Medicine is committed to upholding the rigors of scientific publishing and the veracity of the literature. Reference 1. Legrand FD, Polidori G, Beaumont F, et al. Whole-body cryotherapy as an innovative treatment for COVID 19-induced anosmia-hyposmia: a feasibility study. Epub ahead of print Jan 13, 2022; DOI: 10.1089/jicm.2021.0254.

Anosmia (smell failure) and dysgeusia (taste distortion) in COVID-19: it is genetic

The COVID-19 pandemic is a very contagious respiratory illness with has affected millions of individuals worldwide. In addition to the well-known symptoms of any respiratory virus, COVID-19 can present with anosmia (failure to smell) and dysgeusia (distortion of the sense of taste). It appears to be a genetic link to the biological mechanisms underlying COVID-19-related anosmia and dysgeusia. Significant locus in the vicinity of the UGT2A1 and UGT2A2 genes are currently considered as the main culprit of the symptoms. However, more studies are needed to delineate a clear pathophysiology.Communicated by Ramaswamy H. Sarma.

Alteration of Smell Sensation: Brief Review With Implications for Nursing Care During the COVID-19 Pandemic

ABSTRACT

BACKGROUND: Alteration in olfaction, the sense of smell, can lead to a surprisingly high level of functional disability. Effects can range from mild changes in nutrient intake to a significant decrease in quality of life. Olfactory dysfunction can follow clinical problems such as trauma to the brain and nose. During recent months, in the setting of the current worldwide pandemic of coronavirus disease 2019 (COVID-19), the infection caused by severe acute respiratory syndrome coronavirus 2, it has become clear that olfaction can also be damaged by viruses that enter the body through the nose. METHODS: To learn more about this important clinical problem, we reviewed the current literature about smell sensation and the contextual application of altered olfaction in the setting of COVID-19. Knowledge about this topic, along with other clinical aspects of COVID-19, is expanding quickly. CONCLUSION: Nurses perform assessments, assist with implementing treatment interventions, and provide vital education to patients and their families. These interventions help patients with olfactory dysfunction achieve the best possible functional outcome.

Pathophysiological relationship between COVID-19 and olfactory dysfunction: A systematic review

Introduction

SARS-CoV-2 is the pathogen of COVID-19. The virus is composed of the spike, membrane and envelope. On physiological smell, odoriferous substances bind to proteins secreted by sustentacular cells in order to be processed by olfactory receptor neurons. Olfactory disorder is one of the main manifestations of COVID-19, however, research is still required to clarify the mechanism involved in SARS-CoV-2 induced anosmia.

Objective

This article aims to analyze current scientific evidence intended to elucidate the pathophysiological relationship between COVID-19 and the cause of olfactory disorders.

Methods

Pubmed, Embase, Scopus and ScienceDirect were used to compose this article. The research was conducted on November 24th, 2020. Original articles with experimental studies in human, animal and in vitro, short communications, viewpoint, published in the English language and between 2019 and 2020 were included, all related to the pathophysiological relationship between olfactory disorders and COVID-19 infection.

Results

Both human cell receptors ACE2 and TMPRSS2 are essential for the SARS-CoV-2 entrance. These receptors are mostly present in the olfactory epithelium cells, therefore, the main hypothesis is that anosmia is caused due to damage to non-neuronal cells which, thereafter, affects the normal olfactory metabolism. Furthermore, magnetic resonance imaging studies exhibit a relationship between a reduction on the neuronal epithelium and the olfactory bulb atrophy. Damage to non-neuronal cells explains the average recovery lasting a few weeks. This injury can be exacerbated by an aggressive immune response, which leads to damage to neuronal cells and stem cells inducing a persistent anosmia. Conductive anosmia is not sufficient to explain most cases of COVID-19 induced anosmia.

Conclusion

Olfactory disorders such as anosmia and hyposmia can be caused by COVID-19, the main mechanism is associated with olfactory epithelium damage, targeting predominantly non-neuronal cells. However, neuronal cells can also be affected, worsening the condition of olfactory loss.

Anosmia and dysgeusia in SARS-CoV-2 infection: incidence and effects on COVID-19 severity and mortality, and the possible pathobiology mechanisms - a systematic review and meta-analysis

Background: The present study aimed to determine the global prevalence of anosmia and dysgeusia in coronavirus disease 2019 (COVID-19) patients and to assess their association with severity and mortality of COVID-19. Moreover, this study aimed to discuss the possible pathobiological mechanisms of anosmia and dysgeusia in COVID-19. Methods: Available articles from PubMed, Scopus, Web of Science, and preprint databases (MedRxiv, BioRxiv, and Researchsquare) were searched on November 10th, 2020. Data on the characteristics of the study (anosmia, dysgeusia, and COVID-19) were extracted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Newcastle-Ottawa scale was used to assess research quality. Moreover, the pooled prevalence of anosmia and dysgeusia were calculated, and the association between anosmia and dysgeusia in presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was assessed using the Z test. Results: Out of 32,142 COVID-19 patients from 107 studies, anosmia was reported in 12,038 patients with a prevalence of 38.2% (95% CI: 36.5%, 47.2%); whereas, dysgeusia was reported in 11,337 patients out of 30,901 COVID-19 patients from 101 studies, with prevalence of 36.6% (95% CI: 35.2%, 45.2%), worldwide. Furthermore, the prevalence of anosmia was 10.2-fold higher (OR: 10.21; 95% CI: 6.53, 15.96, p < 0.001) and that of dysgeusia was 8.6-fold higher (OR: 8.61; 95% CI: 5.26, 14.11, p < 0.001) in COVID-19 patients compared to those with other respiratory infections or COVID-19 like illness. To date, no study has assessed the association of anosmia and dysgeusia with severity and mortality of COVID-19. Conclusion: Anosmia and dysgeusia are prevalent in COVID-19 patients compared to those with the other non-COVID-19 respiratory infections. Several possible mechanisms have been hypothesized; however, future studies are warranted to elucidate the definitive mechanisms of anosmia and dysgeusia in COVID-19. Protocol registration: PROSPERO CRD42020223204.

Positividad y proporción para muestras por COVID-19 en Colombia

Introducción: a partir la aparición del brote del síndrome respiratorio agudo severo coronavirus 2 (SARS-CoV-2) en Wuhan, China, en diciembre de 2019, se ha ido propagando a nivel mundial la enfermedad del coronavirus 2019 (COVID-19) enfermedad causada por un nuevo coronavirus, el síndrome respiratorio agudo severo coronavirus 2. Objetivo: describir el comportamiento de positividad y proporción de muestras tomadas para SARS-CoV-2. Metodología: esta investigación se centró en las muestras de PCR procesadas para COVID-19, con la información proveniente del Instituto Nacional de Salud, en el periodo comprendido entre el 6 de marzo al 31 de octubre 2020. Resultados: se pudo evidenciar que el día que se tomó el mayor número de muestras fue el 24-07-2020, con 41.550, seguido del 23-07-2020 con 40.034, y el 22-07-2020 con 39.228 muestras. El día que se presentó el mayor número de muestra positivas fue el 21-07-2020 con 12.160, seguido del 23-07-2020 con 11.983, y 11.879 para el día 29-07-2020. Se apreció también que el 19-07-2020 se presentó la mayor proporción de positividad de las muestras tomadas con 0,33, seguido de 09-08-2020 con 0,32, continuando con el 30-08-2020 con 0,31. Conclusión: hay que seguir en la búsqueda activa de contagiados a través de la práctica de mayor número de pruebas de PCR, antígeno viral y molecular, esta última con un alto nivel de precisión, por parte de las EPS, y que estas a su vez aceleren el proceso de entrega de resultados a las personas.