The novel coronavirus (COVID-19) has become a cause for global concern. Apart from a multitude of symptoms, the virus is known for its ability to cause loss of taste and smell that can be irreversible in a few cases. In fact, even after recovery, post-covid syndrome can still lead to devastating outcomes, specifically with reference to loss of smell and taste. A number of mechanisms that have been postulated include receptor-mediated uptake, increased inflammation, transneuronal migration, and direct damage to the olfactory pathway. Considering how important these two senses are, many psychological, social, and emotional repercussions can be expected. These repercussions include lowering of self-esteem and developmental of mental health issues. Long-term altered taste sensation can also lead to the development of unhealthy eating habits that can result in increasing risk for diabetes and hypertension. A few solutions have been investigated for treating these chemosensory dysfunctions, such as olfactory training, corticosteroids, theophylline and acupuncture. Although the results have been promising but a new modality, virtual reality, requires more in-depth exploration because it targets not only the dysfunction but also the mental health issues being experienced. It is important that affected individuals be provided with strong emotional and family support. Additionally, physicians can help the patients through support groups, cognitive behavioural therapy, olfactory, and virtual reality training.

Olfactory and gustatory dysfunctions: Two systematic review and meta-analysis (26,602 patients from 18 different countries) found that the overall prevalence of alteration of the sense of smell or taste was 47–52% [32, 33]. The loss of smell and taste preceded other symptoms in 20% (95% CI 13–29%) of cases and it was concomitant in 28% (95% CI 22–36%) . A total of 21,515 patients were assessed in a systematic review and meta-analysis. The OR of olfactory and/or gustatory dysfunctions in COVID-19 patients were 11.26 (95% CI 5.41–23.4) when compared with acute respiratory infection without detectable virus and 6.46 (95% CI 2.79–14.97) in patients with other respiratory viruses. The OR of olfactory dysfunction in COVID-19 patients were 11.67 (95% CI 6.43–21.17) when compared with the acute respiratory infection patients without detectable virus and 4.17 (95% CI 1.34–12.98) with other respiratory viruses. The OR of gustatory dysfunction in COVID-19 patients were 12.70 (95% CI 7.9–20.44) when compared with the acute respiratory infection patients without detectable virus and 4.94 (95% CI 1.59–15.31) with other respiratory viruses. Fifty percent (95% CI 36.7–63.3%) of COVID-19 patients had olfactory and/or gustatory dysfunctions .
Ocular symptoms: A cross-sectional study (535 patients from China) showed that conjunctival congestion (5.0%) was one of the COVID-19-related ocular symptoms, which could occur as the initial symptoms. The other ocular symptoms, including increased conjunctival secretion (29.6%), ocular pain (18.5%), photophobia (11.1%), dry eye (37.0%) and tearing (22.2), were also found in patients with conjunctival congestion . A cross-sectional study of 121 patients demonstrated that ocular symptoms including itching, redness, tearing, discharge, and foreign body sensation were among the symptoms of covid-19(5.0%) . A cross-sectional study (56 patients) showed that ocular symptoms (27%) are relatively common in COVID-19 disease and may appear just before the onset of respiratory symptoms . Another cross-sectional study (38 patients) found that one-third (31.6%) of patients with COVID-19 had ocular abnormalities, which frequently occurred in patients with more severe COVID-19 (66.7%) .

Purpose Of Review: This article aims to educate clinical neurologists on the importance of taste and smell disorders in clinical neurology. These disorders commonly occur in head trauma, multiple sclerosis, seizure disorders, and neurodegenerative diseases such as idiopathic Parkinson disease and dementia, mild cognitive impairment, and Alzheimer disease, just to name a few. This article covers the basic anatomy of smell and taste, notes the important points of taking a proper history, and discusses smell and taste testing, which are inexpensive, minimally time-consuming procedures. Recurrent bad smells and tastes are not uncommon in these disorders, which cause major impairment in quality of life, including loss of appetite, decreased eating, and weight loss. The diagnosis and treatment of these disorders will also be discussed.

Recent Findings: Despite past widespread negative prognoses of taste and smell disorders, more recent work in the last 10 years has shown an improved prognosis for smell and taste recovery in most disorders, and recommendations for changes in food preparation have helped many patients enjoy their food and increase their appetite. Recent experimental evidence has shown that smell loss and testing can assist in separating idiopathic Parkinson disease from other parkinsonian syndromes, can suggest which patients with rapid eye movement (REM) sleep behavior disorder will more likely develop Parkinson disease, and can be predictive of the progression of cognitive impairment and Alzheimer dementia.

Summary: This article discusses the common smell and taste disorders that a clinical neurologist will encounter in practice. The anatomy and function of smell and taste will be reviewed, followed by office evaluation and testing. The common disorders will be reviewed, along with their prognosis and management.

Disorders of smell and taste are reported by approximately one-fifth of people 40 years and older, and one-third of people 80 years and older. These disorders affect quality of life and the ability to identify smoke and toxins. Smell and taste disorders can be early signs of dementia or Parkinson disease and are associated with increased mortality. Dysfunction may be apparent or may develop insidiously. Screening questionnaires are available, but many patients are unaware of their disorder. Most smell and taste disorders are due to sinonasal disease but also could be caused by smoking, medications, head trauma, neurodegenerative disease, alcohol dependence, or less common conditions. The differential diagnosis should guide the evaluation and include anterior rhinoscopy and an examination of the oral cavity, head, and cranial nerves. Further investigation is often unnecessary, but nasal endoscopy and computed tomography of the sinuses may be helpful. Magnetic resonance imaging of the head with contrast should be performed if there is an abnormal neurologic examination finding or if trauma or a tumor is suspected. Olfactory testing is indicated in refractory cases or for patients with poor quality of life and disease associated with smell or taste dysfunction. Smell and taste disorders may resolve when reversible causes are treated, but improvement is less likely when they are due to trauma, age, or neurodegenerative disease. Olfactory training is a self-administered mindful exposure therapy that may improve olfactory function. Physicians should encourage patients to ensure that smoke and other alarms are operational and to adhere to food expiration dates.

Purpose: This study investigates the impact of etiology on the epidemiologic profile, disease severity, type of treatment and therapy outcome in smell and taste disorders.

Methods: This is a retrospective analysis of 270 patients that presented with a smell or taste disorder in a specialized, tertiary care center. An established questionnaire was used to collect data from patients and physicians. Olfactometry was performed with the Sniffin' Sticks test kit, while gustometry was performed by taste strips.

Results: Post-traumatic etiology was associated with young age (median 46 years) and male sex, and showed the most severe degrees of smell loss compared to other etiologies (64.3% anosmia). Postinfectious causes occurred more frequently in females (77.3%) and correlated with a history of pharyngeal surgery, suggesting a vulnerability for virally mediated sensory dysfunction following adenoid/tonsil removal. Parosmia also correlated with both postinfectious etiology (62.5%) and female sex. In sinunasal etiology, the presence of nasal polyps worsened the overall olfactory test score by approximately 50%. In particular, smell threshold and discrimination were reduced, while smell identification was not significantly impacted by nasal polyp obstruction. Sinunasal dysfunction was the only etiology to show significant improvement after therapy (73.9% improved). Finally, we could establish good correlations between the subjective impairment and objective dysfunction for each sensory modality.

Conclusion: Each etiology of chemosensory dysfunction shows particular distributions of variables like sex, age, comorbidities and operations, disease severity, sensory threshold, discrimination and identification. This paper offers a detailed account of the correlations between the cause and the characteristics of smell and taste loss.

Olfaction is an essential chemosensory system in the living world. Although less appreciated in humans, smell impairment significantly affects many aspects of quality of life. Smell disorders may be caused by an impaired nasal airway or by lesions in the olfactory system, leading to reduced or distorted smell perception. The most common causes of smell disorders are aging, upper respiratory tract infection, sinonasal disease, and head trauma. Recovery is rarely complete. Counseling is important in progressive or severe smell loss. In patients with distorted smell perception, antidepressant medication is sometimes necessary. Best response to treatment is achieved for nasal obstruction and sinonasal inflammatory disease. Treatment of olfactory impairment caused by sinonasal disease includes medication with topical and systemic steroids, or surgery for refractory cases. Although there are reports that surgical resection of olfactory neurons may lead to reinnervation and recovery of smell, adequate treatment of the smell loss remains an unmet need.

Smell and taste disorders can be challenging to diagnose because of the large number of potential etiologies. Patients are often unable to provide a clear history of symptoms, because they frequently cannot distinguish between difficulties with smell and taste. Standardized questionnaires may be helpful in diagnosis. Smell and taste dysfunction have been implicated in loss of appetite, unintended weight loss, malnutrition, and reduced quality of life. Taste dysfunction may be complete or partial, and affect one or more aspects of taste (sweetness, bitterness, sourness, saltiness, and umami [savory]). An estimated 95% of taste disorders are caused by impairment of smell rather than gustatory loss. The most common causes of olfactory dysfunction include allergic rhinitis, chronic rhinosinusitis (with or without sinonasal polyps), and upper respiratory infection. Other potential causes include head trauma, neurodegenerative diseases (including Parkinson disease and cognitive impairments), and medications. Examination of the nose, mouth, and oropharynx as well as neurologic examination (focusing on cranial nerves I, VII, IX, and X) is essential. Additional assessment such as cognitive testing, nasal endoscopy, computed tomography of the sinuses or nose, or brain magnetic resonance imaging may be indicated. Up to one-half of patients with olfactory dysfunction improve over time. Improvement in olfactory function is inversely correlated with severity and duration of loss, age, smoking, and male sex.

Background: Disorders of the sense of smell have received greater attention because of the frequency with which they occur as a symptom of SARS-CoV-2 infection. Olfactory dysfunction can lead to profound reduction in quality of life and may arise from many different causes.

Methods: A selective literature review was conducted with consideration of the current version of the guideline issued by the Association of the Scientific Medical Societies in Germany.

Results: The cornerstones of diagnosis are the relevant medical history and psychophysical testing of olfactory function using standardized validated tests. Modern treatment strategies are oriented on the cause of the dysfunction. While treatment of the underlying inflammation takes precedence in patients with sinunasal dysosmia, olfactory training is the primary treatment option for other forms of the disorder. The prognosis is determined not only by the cause of the olfactory dysfunction and the patient's age, but also by the olfactory performance as measured at the time of diagnosis.

Conclusion: Options for the treatment of olfactory dysfunction are available but limited, depending on the cause. It is therefore important to carry out a detailed diagnostic work-up and keep the patient informed of the expected course and prognosis.

Decreased olfactory function is very common in the older population, being present in over half of those between the ages of 65 and 80 years and in over three quarters of those over the age of 80 years. Such dysfunction significantly influences physical well-being and quality of life, nutrition, the enjoyment of food, as well as everyday safety. Indeed a disproportionate number of the elderly die in accident gas poisonings each year. As described in this review, multiple factors contribute to such age-related loss, including altered nasal engorgement, increased propensity for nasal disease, cumulative damage to the olfactory epithelium from viral and other environmental insults, decrements in mucosal metabolizing enzymes, ossification of cribriform plate foramina, loss of selectivity of receptor cells to odorants, changes in neurotransmitter and neuromodulator systems, and neuronal expression of aberrant proteins associated with neurodegenerative disease. It is now well established that decreased smell loss can be an early sign of such neurodegenerative diseases as Alzheimer's disease and sporadic Parkinson's disease. In this review we provide an overview of the anatomy and physiology of the aging olfactory system, how this system is clinically evaluated, and the multiple pathophysiological factors that are associated with its dysfunction.

Disorders of smell and taste are reported by approximately one-fifth of people 40 years and older, and one-third of people 80 years and older. These disorders affect quality of life and the ability to identify smoke and toxins. Smell and taste disorders can be early signs of dementia or Parkinson disease and are associated with increased mortality. Dysfunction may be apparent or may develop insidiously. Screening questionnaires are available, but many patients are unaware of their disorder. Most smell and taste disorders are due to sinonasal disease but also could be caused by smoking, medications, head trauma, neurodegenerative disease, alcohol dependence, or less common conditions. The differential diagnosis should guide the evaluation and include anterior rhinoscopy and an examination of the oral cavity, head, and cranial nerves. Further investigation is often unnecessary, but nasal endoscopy and computed tomography of the sinuses may be helpful. Magnetic resonance imaging of the head with contrast should be performed if there is an abnormal neurologic examination finding or if trauma or a tumor is suspected. Olfactory testing is indicated in refractory cases or for patients with poor quality of life and disease associated with smell or taste dysfunction. Smell and taste disorders may resolve when reversible causes are treated, but improvement is less likely when they are due to trauma, age, or neurodegenerative disease. Olfactory training is a self-administered mindful exposure therapy that may improve olfactory function. Physicians should encourage patients to ensure that smoke and other alarms are operational and to adhere to food expiration dates.

Disturbances in both the ability to smell and to taste are common in older persons. Such disturbances influence nutrition, safety, quality of life, and psychological and physical health. The anatomic and physiologic causes of age-related disturbances are multiple and interacting, and depend on genetic and environmental factors. Frank losses of function, distortions, and hallucinations are common. Most distortions resolve over time, although this can take months or even years. Olfactory dysfunction occurs during the earliest stages of several neurologic disorders, most notably Alzheimer's disease and Parkinson's disease, likely heralding the onset of the underlying pathologies.

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.

The novel coronavirus (COVID-19) has become a cause for global concern. Apart from a multitude of symptoms, the virus is known for its ability to cause loss of taste and smell that can be irreversible in a few cases. In fact, even after recovery, post-covid syndrome can still lead to devastating outcomes, specifically with reference to loss of smell and taste. A number of mechanisms that have been postulated include receptor-mediated uptake, increased inflammation, transneuronal migration, and direct damage to the olfactory pathway. Considering how important these two senses are, many psychological, social, and emotional repercussions can be expected. These repercussions include lowering of self-esteem and developmental of mental health issues. Long-term altered taste sensation can also lead to the development of unhealthy eating habits that can result in increasing risk for diabetes and hypertension. A few solutions have been investigated for treating these chemosensory dysfunctions, such as olfactory training, corticosteroids, theophylline and acupuncture. Although the results have been promising but a new modality, virtual reality, requires more in-depth exploration because it targets not only the dysfunction but also the mental health issues being experienced. It is important that affected individuals be provided with strong emotional and family support. Additionally, physicians can help the patients through support groups, cognitive behavioural therapy, olfactory, and virtual reality training.

The mechanisms of olfactory dysfunction in COVID-19 are still unclear. In this review, we examine potential mechanisms that may explain why the sense of smell is lost or altered. Among the current hypotheses, the most plausible is that death of infected support cells in the olfactory epithelium causes, besides altered composition of the mucus, retraction of the cilia on olfactory receptor neurons, possibly because of the lack of support cell-derived glucose in the mucus, which powers olfactory signal transduction within the cilia. This mechanism is consistent with the rapid loss of smell with COVID-19, and its rapid recovery after the regeneration of support cells. Host immune responses that cause downregulation of genes involved in olfactory signal transduction occur too late to trigger anosmia, but may contribute to the duration of the olfactory dysfunction.

Smell and taste disorders can be challenging to diagnose because of the large number of potential etiologies. Patients are often unable to provide a clear history of symptoms, because they frequently cannot distinguish between difficulties with smell and taste. Standardized questionnaires may be helpful in diagnosis. Smell and taste dysfunction have been implicated in loss of appetite, unintended weight loss, malnutrition, and reduced quality of life. Taste dysfunction may be complete or partial, and affect one or more aspects of taste (sweetness, bitterness, sourness, saltiness, and umami [savory]). An estimated 95% of taste disorders are caused by impairment of smell rather than gustatory loss. The most common causes of olfactory dysfunction include allergic rhinitis, chronic rhinosinusitis (with or without sinonasal polyps), and upper respiratory infection. Other potential causes include head trauma, neurodegenerative diseases (including Parkinson disease and cognitive impairments), and medications. Examination of the nose, mouth, and oropharynx as well as neurologic examination (focusing on cranial nerves I, VII, IX, and X) is essential. Additional assessment such as cognitive testing, nasal endoscopy, computed tomography of the sinuses or nose, or brain magnetic resonance imaging may be indicated. Up to one-half of patients with olfactory dysfunction improve over time. Improvement in olfactory function is inversely correlated with severity and duration of loss, age, smoking, and male sex.

Purpose: This study investigates the impact of etiology on the epidemiologic profile, disease severity, type of treatment and therapy outcome in smell and taste disorders.

Methods: This is a retrospective analysis of 270 patients that presented with a smell or taste disorder in a specialized, tertiary care center. An established questionnaire was used to collect data from patients and physicians. Olfactometry was performed with the Sniffin' Sticks test kit, while gustometry was performed by taste strips.

Results: Post-traumatic etiology was associated with young age (median 46 years) and male sex, and showed the most severe degrees of smell loss compared to other etiologies (64.3% anosmia). Postinfectious causes occurred more frequently in females (77.3%) and correlated with a history of pharyngeal... (truncated preview)

Olfaction is an essential chemosensory system in the living world. Although less appreciated in humans, smell impairment significantly affects many aspects of quality of life. Smell disorders may be caused by an impaired nasal airway or by lesions in the olfactory system, leading to reduced or distorted smell perception. The most common causes of smell disorders are aging, upper respiratory tract infection, sinonasal disease, and head trauma. Recovery is rarely complete. Counseling is important in progressive or severe smell loss. In patients with distorted smell perception, antidepressant medication is sometimes necessary. Best response to treatment is achieved for nasal obstruction and sinonasal inflammatory disease. Treatment of olfactory impairment caused by sinonasal disease includes medication with topical and systemic steroids, or surgery for refractory cases. Although there are reports that surgical resection of olfactory neurons may lead to reinnervation and recovery of smell, adequate treatment of the smell loss remains an unmet need.

Purpose Of Review: This article aims to educate clinical neurologists on the importance of taste and smell disorders in clinical neurology. These disorders commonly occur in head trauma, multiple sclerosis, seizure disorders, and neurodegenerative diseases such as idiopathic Parkinson disease and dementia, mild cognitive impairment, and Alzheimer disease, just to name a few. This article covers the basic anatomy of smell and taste, notes the important points of taking a proper history, and discusses smell and taste testing, which are inexpensive, minimally time-consuming procedures. Recurrent bad smells and tastes are not uncommon in these disorders, which cause major impairment in quality of life, including loss of appetite, decreased eating, and weight loss. The diagnosis and treatment of these disorders will also be discussed.

Recent Findings: Despite past widespread negative prognoses of taste and smell disorders, more recent work in the last 10 years has shown an improved prognosis for smell and taste recovery in most disorders, and recommendations for changes in food preparation have helped many patients enjoy their food and increase their appetite. Recent experimental evidence has shown that smell loss and testing can assist in separating idiopathic Parkinson disease from other parkinsonian syndromes, can suggest which patients with rapid eye movement (REM) sleep behavior disorder will more likely develop Parkinson disease, and can be predictive of the progression of cognitive impairment and Alzheimer dementia.

Summary: This article discusses the common smell and taste disorders that a clinical neurologist will encounter in practice. The anatomy and function of smell and taste will be reviewed, followed by office evaluation and testing. The common disorders will be reviewed, along with their prognosis and management.

Although olfaction is the primal sense in animals, its importance in humans is underappreciated. Extensive literature demonstrates that aging is accompanied by olfactory loss and hyposmia/anosmia which is also a feature of several neurodegenerative disorders. Alzheimer's and Parkinson's diseases are characterized by severe olfactory deficits, while problems of olfactory discrimination are less prominent features in several other disorders. Olfactory loss is accompanied by structural abnormalities of the olfactory epithelium, the olfactory bulb and the central olfactory cortices. This review summarizes our present knowledge about the pathological changes in the olfactory system during aging and in various neurodegenerative diseases.

Although many conditions and medications have been associated with chemosensory disturbances, data from major chemosensory clinical research centers support three major disorders as being causative: nasal and paranasal sinus disease (21%), post-upper respiratory tract viral infection (19%), and head trauma (14%). Despite extensive evaluation, 22% of patients do not demonstrate identifiable causation.

Objective: To review the scientific literature on the alterations in the senses of taste and smell in the elderly, including causes, diagnosis, prognosis, and treatment.

Data Sources: Original reports and reviews obtained through MEDLINE searches from 1966 through June 1997 using the MeSH headings of "taste," "taste buds," "taste disorders," "taste thresholds," "smell," "odors," "aged," and "aging." Articles frequently cited in reference lists were also included.

Study Selection: All articles were reviewed, tabulated, and summarized.

Data Extraction: Criteria for extraction included data quality and validity, statistical treatment of the data, venue of publication, and relevance to clinical care.

Conclusion: Losses of taste and smell are common in the elderly and result from normal aging, certain disease states (especially Alzheimer disease), medications, surgical interventions, and environmental exposure. Deficits in these chemical senses cannot only reduce the pleasure and comfort from food, but represent risk factors for nutritional and immune deficiencies as well as adherence to specific dietary regimens. Chemosensory decrements can lead to food poisoning or overexposure to environmentally hazardous chemicals that are otherwise detectable by taste and smell. Use of flavor-enhanced food can increase enjoyment of food and have a positive effect on food intake and immune status.

Among the first clinical symptoms of the SARS-CoV-2 infection is olfactory−gustatory deficit; this continues for weeks and, in some cases, can be persistent. We prospectively evaluated 162 patients affected by COVID-19 using a visual analogue scale (VAS) for nasal and olfactory−gustatory symptoms. Patients were checked after 7, 14, 21, 28, 90, and 180 days. A total of 118 patients (72.8%) reported an olfactory VAS < 7 at baseline (group B), and 44 (27.2%) reported anosmia (VAS ≥ 7) (group A) and underwent the Brief Smell Identification Test (B-SIT) and Burghart Taste Strips (BTS) to quantify the deficit objectively and repeated the tests to confirm the sense recovery. Group A patients showed B-SIT anosmia and hyposmia in 44.2% and 55.8% of cases, respectively. A total of 88.6% of group A patients reported ageusia with VAS ≥ 7, and BTS confirmed 81.8% of ageusia and 18.2% of hypogeusia. VAS smell recovery was recorded starting from 14 days, with normalization at 28 days. The 28-day B-SIT score showed normosmia in 90.6% of group A patients. The mean time for full recovery (VAS = 0) was shorter in group B (22.9 days) than in group A (31.9 days). Chemosensory deficit is frequently the first symptom in patients with COVID-19, and, in most cases, recovery occurs after four weeks.

While olfactory dysfunction associated with coronavirus disease 2019 (COVID-19) has attracted considerable interest, few studies have tracked outcomes at serial time points or beyond 2 weeks. Furthermore, data are conflicting regarding whether COVID-19 severity correlates with degree of olfactory dysfunction. This prospective case-control study analyzed prevalence and severity of subjective loss of smell in outpatients (n = 23) and inpatients (n = 20) with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection vs healthy controls (n = 25). Olfactory dysfunction was reported more commonly in COVID-19 patients than in healthy controls ( < .001), and outpatients paradoxically reported loss of smell more commonly than inpatients ( = .02). Headaches were present in 52% of patients with olfactory dysfunction. Anosmia or hyposmia persisted beyond 5 days but most of the patients recovered by 30 days, suggesting favorable prognosis for olfaction. Differences between inpatients and outpatients are potentially reflective of timeline of olfactory symptoms and contextual factors, underscoring the importance of corroborative objective testing, coupled with careful tracking of temporal relationships.

Introduction: COVID-19 is causing a wide range of clinical manifestations. Severe complications and long-lasting sequelae have been identified. Thus, olfactory disorders are reported in up to 86% of cases in mild and moderate COVID-19 infections. We present the first study comparing simple and complex post-COVID-19 cases with matched non-COVID-19 post-infectious smell and taste disorders.

Methods: A total of 328 patients were recruited from the University Clinic for Flavour, Balance and Sleep, Ear-nose-throat Department, Goedstrup Hospital, Denmark. A non-COVID -19 post-infectious population of 148 individuals was identified from the Redcap database, and was matched by duration of smell and taste disorders. Post-COVID-19 patients were divided into 99 patients with simple smell and taste disorders (only suffering from smell and taste disorders after COVID-19); and (81 patients with complex smell and taste disorder plus several other post-COVID-19 complaints). Besides patient-reported outcome measures (PROM) questionnaires and quality of life score (QoL), ear-nose-throat examination, Mini-Mental State Examination (MMSE), orthonasal smell test (Sniffing's sticks), retronasal quick test, and taste screening were performed.

Results: Cases with post-COVID-19-related smell and taste disorders deviated from non-COVID-19 post-infectious cases; the patients were younger, had a lower occurrence of anosmia/ageusia, and had higher overall smell test scores. In contrast, patients with post-COVID-19-related smell and taste disorders more frequently complained of distorted senses. Parosmia and phantosmia were more prevalent among patients with simple post-COVID-19 complaints than among complex cases and their QoL were more negatively affected.

Conclusion: Smell and taste function differ significantly between post-COVID-19 and other non-COVID-19 post-viral cases.

Level Of Evidence: 3 Laryngoscope, 133:169-174, 2023.

The COVID-19 pandemic has highlighted the relevance of olfactory and gustatory disorders. However, these symptoms can also be caused by various other factors. In this study we aimed to compare the incidence, severity and duration between COVID-19 related and non-COVID-19 related smell and taste disorders. We conducted a longitudinal cohort study using data from the Dutch biobank Lifelines, which includes over 167,000 participants. The data were collected using 27 questionnaires distributed between March 2020 and May 2022. Descriptive data and the incidence of smell and taste loss in both groups were calculated. To visualize the proportion of severity rates of symptoms, a heatmap was created. A survival analysis was conducted and presented in a reversed Kaplan-Meier curve to show the probability of having persistent smell loss in both groups. The study included 235,722 participants. The incidence of smell loss was higher in the COVID-19 positive group, when compared to the COVID-19 negative group. We found varying degrees of symptom severity in COVID-19 positive cases, ranging from mild to severe, while non-COVID-19 related cases mostly reported mild symptoms. The survival outcome for smell and taste loss was 0.12 (SE 0.03, 95% CI 0.07-0.21) in COVID-19 related cases, and was 0.17 (SE 0.03, 95% CI 0.12-0.24) in cases related to other causes. This study reveals a higher incidence and severity of smell and taste loss in individuals with COVID-19 compared to non-COVID-19 related cases. However, non-COVID-19 related smell and taste loss tend to have a longer duration.

Olfaction is an essential chemosensory system in the living world. Although less appreciated in humans, smell impairment significantly affects many aspects of quality of life. Smell disorders may be caused by an impaired nasal airway or by lesions in the olfactory system, leading to reduced or distorted smell perception. The most common causes of smell disorders are aging, upper respiratory tract infection, sinonasal disease, and head trauma. Recovery is rarely complete. Counseling is important in progressive or severe smell loss. In patients with distorted smell perception, antidepressant medication is sometimes necessary. Best response to treatment is achieved for nasal obstruction and sinonasal inflammatory disease. Treatment of olfactory impairment caused by sinonasal disease includes medication with topical and systemic steroids, or surgery for refractory cases. Although there are reports that surgical resection of olfactory neurons may lead to reinnervation and recovery of smell, adequate treatment of the smell loss remains an unmet need.

Disturbances in both the ability to smell and to taste are common in older persons. Such disturbances influence nutrition, safety, quality of life, and psychological and physical health. The anatomic and physiologic causes of age-related disturbances are multiple and interacting, and depend on genetic and environmental factors. Frank losses of function, distortions, and hallucinations are common. Most distortions resolve over time, although this can take months or even years. Olfactory dysfunction occurs during the earliest stages of several neurologic disorders, most notably Alzheimer's disease and Parkinson's disease, likely heralding the onset of the underlying pathologies.

Objective: Although olfaction is often compromised by such factors as head trauma, viruses, and toxic agents, the olfactory epithelium and sectors of the olfactory bulb have the potential for regeneration. This study assessed the degree to which olfactory function changes over time in patients presenting to a university-based smell and taste center with complaints of olfactory dysfunction and the influences of etiology (eg, head trauma, upper respiratory infection), sex, age, smoking behavior, degree of initial dysfunction, and other factors on such change.

Methods: Well-validated odor identification tests were administered to 542 patients on 2 occasions separated from one another by 3 months to 24 years. Multivariable regression and chi2 analyses assessed the influences of the variables on the longitudinal changes in olfactory test scores.

Results: On average, smell test scores improved modestly over time. Patient age, severity of initial olfactory loss, and the duration of dysfunction at first testing were significant predictors of the amount of the change. Etiology, sex, time between the two test administrations, and initial smoking behavior were not significant predictors. The percentage of anosmic and microsmic patients exhibiting statistically significant change in function was 56.72 and 42.86%, respectively. However, only 11.31% of anosmic and 23.31% of microsmic patients regained normal age-related function over time.

Interpretation: Some recovery can be expected in a significant number of patients who experience smell loss. The amount of recovery depends on the degree of initial loss, age, and the duration of loss. Etiology, per se, is not a significant determinant of prognosis, in contrast with what is commonly believed.

Smell and taste disorders can be challenging to diagnose because of the large number of potential etiologies. Patients are often unable to provide a clear history of symptoms, because they frequently cannot distinguish between difficulties with smell and taste. Standardized questionnaires may be helpful in diagnosis. Smell and taste dysfunction have been implicated in loss of appetite, unintended weight loss, malnutrition, and reduced quality of life. Taste dysfunction may be complete or partial, and affect one or more aspects of taste (sweetness, bitterness, sourness, saltiness, and umami [savory]). An estimated 95% of taste disorders are caused by impairment of smell rather than gustatory loss. The most common causes of olfactory dysfunction include allergic rhinitis, chronic rhinosinusitis (with or without sinonasal polyps), and upper respiratory infection. Other potential causes include head trauma, neurodegenerative diseases (including Parkinson disease and cognitive impairments), and medications. Examination of the nose, mouth, and oropharynx as well as neurologic examination (focusing on cranial nerves I, VII, IX, and X) is essential. Additional assessment such as cognitive testing, nasal endoscopy, computed tomography of the sinuses or nose, or brain magnetic resonance imaging may be indicated. Up to one-half of patients with olfactory dysfunction improve over time. Improvement in olfactory function is inversely correlated with severity and duration of loss, age, smoking, and male sex.

Disorders of smell and taste are reported by approximately one-fifth of people 40 years and older, and one-third of people 80 years and older. These disorders affect quality of life and the ability to identify smoke and toxins. Smell and taste disorders can be early signs of dementia or Parkinson disease and are associated with increased mortality. Dysfunction may be apparent or may develop insidiously. Screening questionnaires are available, but many patients are unaware of their disorder. Most smell and taste disorders are due to sinonasal disease but also could be caused by smoking, medications, head trauma, neurodegenerative disease, alcohol dependence, or less common conditions. The differential diagnosis should guide the evaluation and include anterior rhinoscopy and an examination of the oral cavity, head, and cranial nerves. Further investigation is often unnecessary, but nasal endoscopy and computed tomography of the sinuses may be helpful. Magnetic resonance imaging of the head with contrast should be performed if there is an abnormal neurologic examination finding or if trauma or a tumor is suspected. Olfactory testing is indicated in refractory cases or for patients with poor quality of life and disease associated with smell or taste dysfunction. Smell and taste disorders may resolve when reversible causes are treated, but improvement is less likely when they are due to trauma, age, or neurodegenerative disease. Olfactory training is a self-administered mindful exposure therapy that may improve olfactory function. Physicians should encourage patients to ensure that smoke and other alarms are operational and to adhere to food expiration dates.

The novel coronavirus (COVID-19) has become a cause for global concern. Apart from a multitude of symptoms, the virus is known for its ability to cause loss of taste and smell that can be irreversible in a few cases. In fact, even after recovery, post-covid syndrome can still lead to devastating outcomes, specifically with reference to loss of smell and taste. A number of mechanisms that have been postulated include receptor-mediated uptake, increased inflammation, transneuronal migration, and direct damage to the olfactory pathway. Considering how important these two senses are, many psychological, social, and emotional repercussions can be expected. These repercussions include lowering of self-esteem and developmental of mental health issues. Long-term altered taste sensation can also lead to the development of unhealthy eating habits that can result in increasing risk for diabetes and hypertension. A few solutions have been investigated for treating these chemosensory dysfunctions, such as olfactory training, corticosteroids, theophylline and acupuncture. Although the results have been promising but a new modality, virtual reality, requires more in-depth exploration because it targets not only the dysfunction but also the mental health issues being experienced. It is important that affected individuals be provided with strong emotional and family support. Additionally, physicians can help the patients through support groups, cognitive behavioural therapy, olfactory, and virtual reality training.

Evidence is insufficient to provide a recommendation for or against any intervention.
How should smell and taste disturbances be managed?
A Cochrane systematic review aimed to assess interventions to treat persistent COVID-19–related olfactory dysfunction. The search for RCTs for inclusion resulted in only one small trial comparing prednisone plus nasal irrigation (intranasal steroids with mucolytic and decongestant agents) for 15 days versus no treatment. The study included nine patients in each arm but was graded as high risk of bias, and the results were reported only up until 40 days, limiting the ability to draw conclusions []. The manuscript included a consensus statement by the clinical olfactory working group, which recommended routine use of olfactory training, but was controversial regarding pharmacologic therapy with a recommendation to consider steroids (nasal or systemic), theophylline, and sodium citrate.
A role of smoking and olfactory dysfunction in general has been discussed. The consensus document states that the benefit of smoking cessation in patients with long-COVID anosmia/ageusia is not clear, but an overall benefit justifies the recommendation. Other therapies described that need further study include oral and intranasal corticosteroids, theophylline, sodium citrate, N-methyl D-aspartate antagonist (caroverine), traditional Chinese acupuncture, a-lipoic acid, vitamin A, minocycline, and zinc sulphate [
Evidence is insufficient to provide a recommendation for or against any intervention. Due to its simplicity and safety, olfactory training should probably be suggested for all patients. Physicians should discuss the likelihood for spontaneous recovery with patients, and other interventions should be suggested only in clinical trials. Smoking cessation should be recommended.

Olfaction is an essential chemosensory system in the living world. Although less appreciated in humans, smell impairment significantly affects many aspects of quality of life. Smell disorders may be caused by an impaired nasal airway or by lesions in the olfactory system, leading to reduced or distorted smell perception. The most common causes of smell disorders are aging, upper respiratory tract infection, sinonasal disease, and head trauma. Recovery is rarely complete. Counseling is important in progressive or severe smell loss. In patients with distorted smell perception, antidepressant medication is sometimes necessary. Best response to treatment is achieved for nasal obstruction and sinonasal inflammatory disease. Treatment of olfactory impairment caused by sinonasal disease includes medication with topical and systemic steroids, or surgery for refractory cases. Although there are reports that surgical resection of olfactory neurons may lead to reinnervation and recovery of smell, adequate treatment of the smell loss remains an unmet need.

Background: Disorders of the sense of smell have received greater attention because of the frequency with which they occur as a symptom of SARS-CoV-2 infection. Olfactory dysfunction can lead to profound reduction in quality of life and may arise from many different causes.

Methods: A selective literature review was conducted with consideration of the current version of the guideline issued by the Association of the Scientific Medical Societies in Germany.

Results: The cornerstones of diagnosis are the relevant medical history and psychophysical testing of olfactory function using standardized validated tests. Modern treatment strategies are oriented on the cause of the dysfunction. While treatment of the underlying inflammation takes precedence in patients with sinunasal dysosmia, olfactory training is the primary treatment option for other forms of the disorder. The prognosis is determined not only by the cause of the olfactory dysfunction and the patient's age, but also by the olfactory performance as measured at the time of diagnosis.

Conclusion: Options for the treatment of olfactory dysfunction are available but limited, depending on the cause. It is therefore important to carry out a detailed diagnostic work-up and keep the patient informed of the expected course and prognosis.

The loss of the senses of smell (anosmia) and taste (ageusia) are rather common disorders, affecting up to 20% of the adult population. Yet, this condition has not received the attention it deserves, most probably because per se such a disorder is not life threatening. However, loss of olfactory function significantly reduces the quality of life of the affected patients, leading to dislike in food and insufficient, exaggerated or unbalanced food intake, unintentional exposure to toxins such as household gas, social isolation, depression, and an overall insecurity. Not only is olfactory dysfunction rather prevalent in the healthy population, it is, in many instances, also a correlate or an early indicator of a panoply of diseases. Importantly, olfactory dysfunction is linked to the two most prominent neurodegenerative disorders, Parkinson's disease and Alzheimer's disease. Anosmia and hyposmia (reduced sense of smell) affect a majority of patients years before the onset of cognitive or motor symptoms, establishing olfactory dysfunction as early biomarker that can enable earlier diagnosis and preventative treatments. In the current health crisis caused by SARS-CoV2, anosmia and dysgeusia as early-onset symptoms in virus-positive patients may prove to be highly relevant and crucial for pre-symptomatic Covid-19 detection from a public health perspective, preceding by days the more classical respiratory tract symptoms such as cough, tightness of the chest or fever. Thus, the olfactory system seems to be at the frontline of pathologic assault, be it through pathogens or insults that can lead to or at least associate with neurodegeneration. The aim of this review is to assemble current knowledge from different medical fields that all share a common denominator, olfactory/gustatory dysfunction, and to distill overarching etiologies and disease progression mechanisms.

Olfactory disorders have been increasingly reported in individuals infected with SARS-CoV-2, the virus causing the coronavirus disease 2019 (COVID-19). Losing the sense of smell has a strong impact on the quality of life, since it may lead to malnutrition, weight loss, food poisoning, depression, and exposure to dangerous chemicals. Individuals who suffer from anosmia (inability to smell) also cannot sense the flavor of food, which is a combination of taste and smell. Interestingly, infected individuals have reported sudden loss of smell with no congested nose, as is frequently observed in common colds or other upper respiratory tract infections. These observations suggest that SARS-CoV-2 infection leads to olfactory loss through a distinct mechanism, which is still unclear. This article provides an overview of olfactory loss and the recent findings relating to COVID-19. Possible mechanisms of SARS-CoV-2-induced olfactory loss are also discussed.

Disorders of smell and taste are reported by approximately one-fifth of people 40 years and older, and one-third of people 80 years and older. These disorders affect quality of life and the ability to identify smoke and toxins. Smell and taste disorders can be early signs of dementia or Parkinson disease and are associated with increased mortality. Dysfunction may be apparent or may develop insidiously. Screening questionnaires are available, but many patients are unaware of their disorder. Most smell and taste disorders are due to sinonasal disease but also could be caused by smoking, medications, head trauma, neurodegenerative disease, alcohol dependence, or less common conditions. The differential diagnosis should guide the evaluation and include anterior rhinoscopy and an examination of the oral cavity, head, and cranial nerves. Further investigation is often unnecessary, but nasal endoscopy and computed tomography of the sinuses may be helpful. Magnetic resonance imaging of the head with contrast should be performed if there is an abnormal neurologic examination finding or if trauma or a tumor is suspected. Olfactory testing is indicated in refractory cases or for patients with poor quality of life and disease associated with smell or taste dysfunction. Smell and taste disorders may resolve when reversible causes are treated, but improvement is less likely when they are due to trauma, age, or neurodegenerative disease. Olfactory training is a self-administered mindful exposure therapy that may improve olfactory function. Physicians should encourage patients to ensure that smoke and other alarms are operational and to adhere to food expiration dates.

Background: The impact of anosmia on quality-of-life (QoL) for patients with aspirin-exacerbated respiratory disease (AERD) is poorly understood. We aimed to investigate how the severity of smell loss and olfactory dysfunction (OD) in patients with AERD affects their QoL, mental health and physical well-being.

Methods: Five validated QoL questionnaires (Sinonasal Outcome Test-22, Asthma Control Test, Healthy Days Core Module-4, Short Form-36 and Patient Health Questionnaire-4) and two newly developed questionnaires assessing severity and consequences of OD were electronically sent to all 2913 patients in the Brigham and Women's Hospital AERD registry. Responses were received from 853 participants for analysis.

Results: Overall, 85% of participants reported a present diminished sense of smell and/or taste, and 30% categorized their OD severity was, "as bad as it can be." There were significant relationships between the severity of self-reported OD and both psychological distress and general health scores, even after adjusting for asthma control. Additionally, incidence rates for physically and mentally unhealthy days in the prior month were higher for patients with moderate or severe OD than for normosmic patients. Patients with diminished smell responded that they could not identify spoiled food (86%), did not enjoy food (71%), felt unsafe (63%) and had encountered dangerous situations (51%) as consequences of their OD.

Conclusions: Anosmia and hyposmia severely impact the physical, emotional and mental health of AERD patients, and lead to safety concerns in their daily lives. The importance of olfaction and the relevance of OD to patients' QoL should be acknowledged and evaluated by clinicians caring for these patients.

Chemosensory disorders of smell or taste in humans have been attributed to various physiological and environmental factors including aging and disease conditions. Aroma and taste greatly condition our food preference, selection and, consumption; the decreased appetite in patients with known neurodegenerative diseases may lead to dietary restrictions that could negatively impact nutritional and health status. The decline in olfactory and gustatory systems in patients with Alzheimer disease and various types of stroke are described.

Olfactory disorders are common and affect about one-fifth of the general population. The main causes of olfactory loss are post viral upper respiratory infection, nasal/sinus disease, and head trauma and are therefore very frequent among patients in ear, nose, and throat clinics. We have systematically reviewed the impact of quantitative, qualitative, and congenital olfactory disorders on daily life domains as well as on general quality of life and depression. From the extensive body of literature, it can be concluded that loss of the sense of smell leads to disturbances in important areas, mainly in food enjoyment, detecting harmful food and smoke, and to some extent in social situations and working life. Most patients seem to deal well and manage those restrictions. However, a smaller proportion has considerable problems and expresses a noticeable reduction in general quality of life and enhanced depression. The impact of coping strategies is discussed.

Objective: To review the scientific literature on the alterations in the senses of taste and smell in the elderly, including causes, diagnosis, prognosis, and treatment.

Data Sources: Original reports and reviews obtained through MEDLINE searches from 1966 through June 1997 using the MeSH headings of "taste," "taste buds," "taste disorders," "taste thresholds," "smell," "odors," "aged," and "aging." Articles frequently cited in reference lists were also included.

Study Selection: All articles were reviewed, tabulated, and summarized.

Data Extraction: Criteria for extraction included data quality and validity, statistical treatment of the data, venue of publication, and relevance to clinical care.

Conclusion: Losses of taste and smell are common in the elderly and result from normal aging, certain disease states (especially Alzheimer disease), medications, surgical interventions, and environmental exposure. Deficits in these chemical senses cannot only reduce the pleasure and comfort from food, but represent risk factors for nutritional and immune deficiencies as well as adherence to specific dietary regimens. Chemosensory decrements can lead to food poisoning or overexposure to environmentally hazardous chemicals that are otherwise detectable by taste and smell. Use of flavor-enhanced food can increase enjoyment of food and have a positive effect on food intake and immune status.

Decreased olfactory function is very common in the older population, being present in over half of those between the ages of 65 and 80 years and in over three quarters of those over the age of 80 years. Such dysfunction significantly influences physical well-being and quality of life, nutrition, the enjoyment of food, as well as everyday safety. Indeed a disproportionate number of the elderly die in accident gas poisonings each year. As described in this review, multiple factors contribute to such age-related loss, including altered nasal engorgement, increased propensity for nasal disease, cumulative damage to the olfactory epithelium from viral and other environmental insults, decrements in mucosal metabolizing enzymes, ossification of cribriform plate foramina, loss of selectivity of receptor cells to odorants, changes in neurotransmitter and neuromodulator systems, and neuronal expression of aberrant proteins associated with neurodegenerative disease. It is now well established that decreased smell loss can be an early sign of such neurodegenerative diseases as Alzheimer's disease and sporadic Parkinson's disease. In this review we provide an overview of the anatomy and physiology of the aging olfactory system, how this system is clinically evaluated, and the multiple pathophysiological factors that are associated with its dysfunction.

Disorders of smell and taste are reported by approximately one-fifth of people 40 years and older, and one-third of people 80 years and older. These disorders affect quality of life and the ability to identify smoke and toxins. Smell and taste disorders can be early signs of dementia or Parkinson disease and are associated with increased mortality. Dysfunction may be apparent or may develop insidiously. Screening questionnaires are available, but many patients are unaware of their disorder. Most smell and taste disorders are due to sinonasal disease but also could be caused by smoking, medications, head trauma, neurodegenerative disease, alcohol dependence, or less common conditions. The differential diagnosis should guide the evaluation and include anterior rhinoscopy and an examination of the oral cavity, head, and cranial nerves. Further investigation is often unnecessary, but nasal endoscopy and computed tomography of the sinuses may be helpful. Magnetic resonance imaging of the head with contrast should be performed if there is an abnormal neurologic examination finding or if trauma or a tumor is suspected. Olfactory testing is indicated in refractory cases or for patients with poor quality of life and disease associated with smell or taste dysfunction. Smell and taste disorders may resolve when reversible causes are treated, but improvement is less likely when they are due to trauma, age, or neurodegenerative disease. Olfactory training is a self-administered mindful exposure therapy that may improve olfactory function. Physicians should encourage patients to ensure that smoke and other alarms are operational and to adhere to food expiration dates.

Background: Disorders of the sense of smell have received greater attention because of the frequency with which they occur as a symptom of SARS-CoV-2 infection. Olfactory dysfunction can lead to profound reduction in quality of life and may arise from many different causes.

Methods: A selective literature review was conducted with consideration of the current version of the guideline issued by the Association of the Scientific Medical Societies in Germany.

Results: The cornerstones of diagnosis are the relevant medical history and psychophysical testing of olfactory function using standardized validated tests. Modern treatment strategies are oriented on the cause of the dysfunction. While treatment of the underlying inflammation takes precedence in patients with sinunasal dysosmia, olfactory training is the primary treatment option for other forms of the disorder. The prognosis is determined not only by the cause of the olfactory dysfunction and the patient's age, but also by the olfactory performance as measured at the time of diagnosis.

Conclusion: Options for the treatment of olfactory dysfunction are available but limited, depending on the cause. It is therefore important to carry out a detailed diagnostic work-up and keep the patient informed of the expected course and prognosis.

Evidence is insufficient to provide a recommendation for or against any intervention.
How should smell and taste disturbances be managed?
A Cochrane systematic review aimed to assess interventions to treat persistent COVID-19–related olfactory dysfunction. The search for RCTs for inclusion resulted in only one small trial comparing prednisone plus nasal irrigation (intranasal steroids with mucolytic and decongestant agents) for 15 days versus no treatment. The study included nine patients in each arm but was graded as high risk of bias, and the results were reported only up until 40 days, limiting the ability to draw conclusions []. The manuscript included a consensus statement by the clinical olfactory working group, which recommended routine use of olfactory training, but was controversial regarding pharmacologic therapy with a recommendation to consider steroids (nasal or systemic), theophylline, and sodium citrate.
A role of smoking and olfactory dysfunction in general has been discussed. The consensus document states that the benefit of smoking cessation in patients with long-COVID anosmia/ageusia is not clear, but an overall benefit justifies the recommendation. Other therapies described that need further study include oral and intranasal corticosteroids, theophylline, sodium citrate, N-methyl D-aspartate antagonist (caroverine), traditional Chinese acupuncture, a-lipoic acid, vitamin A, minocycline, and zinc sulphate [
Evidence is insufficient to provide a recommendation for or against any intervention. Due to its simplicity and safety, olfactory training should probably be suggested for all patients. Physicians should discuss the likelihood for spontaneous recovery with patients, and other interventions should be suggested only in clinical trials. Smoking cessation should be recommended.

Olfaction is an essential chemosensory system in the living world. Although less appreciated in humans, smell impairment significantly affects many aspects of quality of life. Smell disorders may be caused by an impaired nasal airway or by lesions in the olfactory system, leading to reduced or distorted smell perception. The most common causes of smell disorders are aging, upper respiratory tract infection, sinonasal disease, and head trauma. Recovery is rarely complete. Counseling is important in progressive or severe smell loss. In patients with distorted smell perception, antidepressant medication is sometimes necessary. Best response to treatment is achieved for nasal obstruction and sinonasal inflammatory disease. Treatment of olfactory impairment caused by sinonasal disease includes medication with topical and systemic steroids, or surgery for refractory cases. Although there are reports that surgical resection of olfactory neurons may lead to reinnervation and recovery of smell, adequate treatment of the smell loss remains an unmet need.

Purpose Of Review: Olfactory dysfunction is a prevalent condition affecting 5-15% of the general population, with significant impact on quality of life. This review summarizes the most recent and relevant literature in the treatment of olfactory dysfunction.

Recent Findings: Current evidence supports the short-term use of topical corticosteroids and systemic therapy. These treatments may occur in conjunction with olfactory training, which is well supported by the literature. While there are several additional treatments currently under investigation, meaningful conclusions are not yet able to be made regarding their efficacy. The treatment of olfactory dysfunction is targeted at the suspected etiology when possible. After normal aging, chronic rhinosinusitis, post-infectious sequelae including as a result SARS-CoV-2 infection (COVID-19), and head trauma are the most common causes. Current evidence supports the short-term use of topical corticosteroids and systemic therapy. Several additional treatments are under investigation but recommendations for their use cannot currently be made.

Objective We evaluated the severity of olfactory impairment according to risk factors, compared responses with risk factors and treatment timing, and investigated prognosis according to treatments. Study design Case series with chart review. Setting Tertiary referral center. Subjects and Methods We retrospectively reviewed medical records of patients complaining of loss of their sense of smell between January 2006 and May 2016. In total, 491 patients were included. We evaluated olfactory function using the Connecticut Chemosensory Clinical Research Center test (threshold test) and Cross-cultural Smell Identification Test. Results Post-upper respiratory infection patients showed better results than those with other risk factors (59.6% recovered). Patients with head trauma (12.5% recovered) and congenital olfactory dysfunction (0% recovered) showed poorer results. Earlier treatment showed better olfactory recovery outcomes for post-upper respiratory infection ( P = .001), head trauma ( P = .022), and nasal/sinus surgery ( P = .009). Xerostomia ( P = .73) and idiopathy ( P = .365) showed no significant difference in terms of treatment timing. The threshold test better reflected subjective recovery than the identification test. The systemic + topical steroid group and the systemic steroid treatment group both showed better smell recovery outcomes than the group with topical treatment alone (both, P < .001). However, there was no significant difference between the systemic treatment group and the systemic + topical treatment group ( P = .978). Conclusions Our findings suggest that the duration of smell loss is important for better olfactory outcomes with most etiologies. Also, the effects of systemic steroids were better than those of topical steroids, regardless of combined treatment.

Objective We evaluated the severity of olfactory impairment according to risk factors, compared responses with risk factors and treatment timing, and investigated prognosis according to treatments. Study design Case series with chart review. Setting Tertiary referral center. Subjects and Methods We retrospectively reviewed medical records of patients complaining of loss of their sense of smell between January 2006 and May 2016. In total, 491 patients were included. We evaluated olfactory function using the Connecticut Chemosensory Clinical Research Center test (threshold test) and Cross-cultural Smell Identification Test. Results Post-upper respiratory infection patients showed better results than those with other risk factors (59.6% recovered). Patients with head trauma (12.5% recovered) and congenital olfactory dysfunction (0% recovered) showed poorer results. Earlier treatment showed better olfactory recovery outcomes for post-upper respiratory infection ( P = .001), head trauma ( P = .022), and nasal/sinus surgery ( P = .009). Xerostomia ( P = .73) and idiopathy ( P = .365) showed no significant difference in terms of treatment timing. The threshold test better reflected subjective recovery than the identification test. The systemic + topical steroid group and the systemic steroid treatment group both showed better smell recovery outcomes than the group with topical treatment alone (both, P < .001). However, there was no significant difference between the systemic treatment group and the systemic + topical treatment group ( P = .978). Conclusions Our findings suggest that the duration of smell loss is important for better olfactory outcomes with most etiologies. Also, the effects of systemic steroids were better than those of topical steroids, regardless of combined treatment.

While olfactory dysfunction associated with coronavirus disease 2019 (COVID-19) has attracted considerable interest, few studies have tracked outcomes at serial time points or beyond 2 weeks. Furthermore, data are conflicting regarding whether COVID-19 severity correlates with degree of olfactory dysfunction. This prospective case-control study analyzed prevalence and severity of subjective loss of smell in outpatients (n = 23) and inpatients (n = 20) with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection vs healthy controls (n = 25). Olfactory dysfunction was reported more commonly in COVID-19 patients than in healthy controls ( < .001), and outpatients paradoxically reported loss of smell more commonly than inpatients ( = .02). Headaches were present in 52% of patients with olfactory dysfunction. Anosmia or hyposmia persisted beyond 5 days but most of the patients recovered by 30 days, suggesting favorable prognosis for olfaction. Differences between inpatients and outpatients are potentially reflective of timeline of olfactory symptoms and contextual factors, underscoring the importance of corroborative objective testing, coupled with careful tracking of temporal relationships.

Disorders of smell and taste are reported by approximately one-fifth of people 40 years and older, and one-third of people 80 years and older. These disorders affect quality of life and the ability to identify smoke and toxins. Smell and taste disorders can be early signs of dementia or Parkinson disease and are associated with increased mortality. Dysfunction may be apparent or may develop insidiously. Screening questionnaires are available, but many patients are unaware of their disorder. Most smell and taste disorders are due to sinonasal disease but also could be caused by smoking, medications, head trauma, neurodegenerative disease, alcohol dependence, or less common conditions. The differential diagnosis should guide the evaluation and include anterior rhinoscopy and an examination of the oral cavity, head, and cranial nerves. Further investigation is often unnecessary, but nasal endoscopy and computed tomography of the sinuses may be helpful. Magnetic resonance imaging of the head with contrast should be performed if there is an abnormal neurologic examination finding or if trauma or a tumor is suspected. Olfactory testing is indicated in refractory cases or for patients with poor quality of life and disease associated with smell or taste dysfunction. Smell and taste disorders may resolve when reversible causes are treated, but improvement is less likely when they are due to trauma, age, or neurodegenerative disease. Olfactory training is a self-administered mindful exposure therapy that may improve olfactory function. Physicians should encourage patients to ensure that smoke and other alarms are operational and to adhere to food expiration dates.

Olfactory dysfunction is a common complaint for patients with chronic rhinosinusitis, because smell loss decreases a patient's quality of life. Smell loss is caused by obstruction from polyps, nasal discharge, and mucosal edema, as well as inflammatory changes within the olfactory epithelium. Addressing olfaction before endoscopic sinus and skull base surgery is important in order to set postoperative expectations, because an improvement in smell is difficult to predict. Several commercially available olfactory testing measures are available and can easily be administered in clinic. During surgery, careful dissection within the olfactory cleft is recommended in order to optimize postoperative olfactory function.

Objective We evaluated the severity of olfactory impairment according to risk factors, compared responses with risk factors and treatment timing, and investigated prognosis according to treatments. Study design Case series with chart review. Setting Tertiary referral center. Subjects and Methods We retrospectively reviewed medical records of patients complaining of loss of their sense of smell between January 2006 and May 2016. In total, 491 patients were included. We evaluated olfactory function using the Connecticut Chemosensory Clinical Research Center test (threshold test) and Cross-cultural Smell Identification Test. Results Post-upper respiratory infection patients showed better results than those with other risk factors (59.6% recovered). Patients with head trauma (12.5% recovered) and congenital olfactory dysfunction (0% recovered) showed poorer results. Earlier treatment showed better olfactory recovery outcomes for post-upper respiratory infection ( P = .001), head trauma ( P = .022), and nasal/sinus surgery ( P = .009). Xerostomia ( P = .73) and idiopathy ( P = .365) showed no significant difference in terms of treatment timing. The threshold test better reflected subjective recovery than the identification test. The systemic + topical steroid group and the systemic steroid treatment group both showed better smell recovery outcomes than the group with topical treatment alone (both, P < .001). However, there was no significant difference between the systemic treatment group and the systemic + topical treatment group ( P = .978). Conclusions Our findings suggest that the duration of smell loss is important for better olfactory outcomes with most etiologies. Also, the effects of systemic steroids were better than those of topical steroids, regardless of combined treatment.

Background: Disorders of the sense of smell have received greater attention because of the frequency with which they occur as a symptom of SARS-CoV-2 infection. Olfactory dysfunction can lead to profound reduction in quality of life and may arise from many different causes.

Methods: A selective literature review was conducted with consideration of the current version of the guideline issued by the Association of the Scientific Medical Societies in Germany.

Results: The cornerstones of diagnosis are the relevant medical history and psychophysical testing of olfactory function using standardized validated tests. Modern treatment strategies are oriented on the cause of the dysfunction. While treatment of the underlying inflammation takes precedence in patients with sinunasal dysosmia, olfactory training is the primary treatment option for other forms of the disorder. The prognosis is determined not only by the cause of the olfactory dysfunction and the patient's age, but also by the olfactory performance as measured at the time of diagnosis.

Conclusion: Options for the treatment of olfactory dysfunction are available but limited, depending on the cause. It is therefore important to carry out a detailed diagnostic work-up and keep the patient informed of the expected course and prognosis.

Background: Olfactory impairment is one of important symptoms of Chronic rhinosinusitis with nasal polyps (CRSwNP). However, the relationship between course of olfactory impairment and postoperative symptom improvement was still unclear.

Objective: The aim of this study was to assess the relationship between the self-reported course of olfactory loss and the degree of improvement in olfaction to determine the timing for successful surgical intervention in improving olfaction in patients with CRSwNP.

Materials And Methods: A total of 86 CRSwNP patients with loss of smell and undergoing functional endoscopic sinus surgery (FESS) were recruited consecutively. The self-reported course of smell lose before treatment was recorded. Olfactory function was recorded before and after FESS using T&T Olfactometry.

Results: Fifty-seven patients demonstrated recovery of olfaction and 29 patients no-recovery. The average recovery time of smell loss in the study was 2.6 weeks. The course of smell loss showed moderate accuracy as a marker for determining the timing for successful FESS; with up to 4.5 years of self-reported smell loss being the cut-off point for recovery of smell following FESS.

Conclusion: This study suggests that FESS in CRSwNP patients with self-reported significant olfactory impairment for less than 4.5 years may lead to improvement in olfaction.

Significance: FESS in CRSwNP patients with self-reported significant olfactory impairment persisting for less than 4.5 years may lead to considerable improvement in olfaction in these patients.