Taste and smell function in chronic disease: a review of clinical and biochemical evaluations of taste and smell dysfunction in over 5000 patients at The Taste and Smell Clinic in Washington, DC

Gustatory dysfunction and long COVID in Chinese patients with COVID-19: A 6-month follow-up study

AIMS

To evaluate long COVID of gustatory dysfunction and the associated risk factors regarding onset and recovery in Chinese patients.

METHODS

We conducted a cross-sectional study of patients with SARS-CoV-2 Omicron infection at Changxing Mobile Cabin Hospital in Shanghai, China, from March to May 2022. A prospective follow-up of patients with gustatory dysfunction was conducted at 6 months after discharge.

RESULTS

In total, 18.48% (241/1304) reported gustatory dysfunction. The 6-month follow-up response rate was 89.63% (216/241) and 74.02% recovered their taste sense within 1-3 weeks. A total of 20.37% of patients (44/216) presented with long COVID. Symptoms persisted for 12 patients (5.56%) after 6 months. Having multiple taste impairments (OR, 2.364; 95% CI, 1.286-4.348; p = 0.006) was associated with a higher risk of gustatory dysfunction with long COVID. Having received a COVID-19 vaccine booster was positively associated with taste sensation recovery (HR, 1.344; 95% CI, 1.012-1.785; p = 0.041).

CONCLUSIONS

About 20.37% of patients with COVID-19 might develop long COVID of gustatory dysfunction and 5.56% with persisting changes in their sense of taste. Most patients recovered taste sensations within 1-3 weeks after COVID-19 symptom onset and receiving a booster shot of the COVID-19 vaccine presented a protective effect on the taste sensation recovery.

Taste disturbance in patients with advanced cancer: a scoping review of clinical features and complications

PURPOSE

The purpose of this scoping review is to appraise the published literature on taste disturbance in patients with advanced cancer, with the specific objectives being to determine its prevalence, clinical features and complications.

METHODS

This scoping review was conducted using the recommended methodological framework. A detailed search of databases (Medline, Embase, CINAHL and PsycInfo) was conducted to identify eligible studies: eligible studies needed to include patients with advanced cancer and needed to include details of clinical features and/or complications of taste disturbance. Standard bibliographic/systematic review software was used to store the records and manage the review process, respectively.

RESULTS

Twenty-five studies were identified from the database searches. The studies identified included eight physical and/or psychological symptom studies, six symptom cluster studies, five oral symptom studies and six taste and/or smell specific studies. Detailed data is presented on the clinical features and complications of taste disturbance and on the symptom clusters involving taste disturbance in this cohort of patients.

CONCLUSION

This scoping review identified a relatively small number of relevant studies involving a relatively small number of participants. Nevertheless, it confirms that taste disturbance is a common problem in patients with advanced cancer and is associated with significant morbidity because of the primary condition and the associated complications.

Characteristics of Chemosensory Perception in Long COVID and COVID Reinfection

Emerging data suggest an increasing prevalence of persistent symptoms in individuals affected by coronavirus disease-19 (COVID-19). The objective of this study was to determine the relative frequency of altered taste and smell in COVID reinfection (multiple COVID positive tests) and long COVID (one COVID positive test). We sent an electronic survey to patients in the Indiana University Health COVID registry with positive COVID test results, querying if they were experiencing symptoms consistent with long COVID including altered chemosensory perceptions. Among the 225 respondents, a greater long COVID burden and COVID reinfection was observed in women. Joint pain was reported as the most common symptom experienced by 18% of individuals in the long COVID cohort. In the COVID reinfection cohort >20% of individuals reported headache, joint pain, and cough. Taste perception worse than pre-COVID was reported by 29% and 42% of individuals in the long COVID and COVID reinfection cohorts, respectively. Smell perception worse than pre-COVID was reported by 37% and 46% of individuals in long COVID and COVID reinfection cohorts, respectively. Further, Chi-square test suggested significant association between pre-COVID severity of taste/smell perception and headache in both cohorts. Our findings highlight the prevalence of persistent chemosensory dysfunction for two years and longer in long COVID and COVID reinfection.

A prospective study of dysgeusia and related symptoms in patients with multiple myeloma after autologous hematopoietic cell transplantation

BACKGROUND

Dysgeusia is a common but understudied complication in patients undergoing autologous hematopoietic cell transplantation (auto-HCT). We assessed the feasibility of using chemical gustometry (CG) to measure dysgeusia and explored its associations with symptom burden, nutrition, chemotherapy pharmacokinetics (PK), and the oral microbiome.

METHODS

We conducted a single-center, prospective feasibility study (NCT03276481) of patients with multiple myeloma undergoing auto-HCT. CG was performed longitudinally testing five flavors (sweet, sour, salty, bitter, umami) to calculate a total taste score (maximum score, 30). We measured caloric intake and patient-reported symptoms, assessing their correlation with oral microbiota composition and salivary and blood melphalan PK exposure.

RESULTS

Among all 45 patients, 39 (87%) completed at least four (>60%) and 22 (49%) completed all six CG assessments. Median total CG scores remained stable over time but were lowest at day +7 (27, range 24-30) with recovery by day +100. Symptom burden was highest by day +10 (area under the curve, 2.9; range, 1.0-4.6) corresponding with the lowest median overall caloric intake (1624 kcal; range, 1345-2267). Higher serum/salivary melphalan levels correlated with higher patient-reported dysgeusia and lower caloric intake. Oral microbiota α-diversity was stable early and increased slightly by day +100.

CONCLUSIONS

Assessment of dysgeusia by CG is feasible after auto-HCT. Most dysgeusia, symptom burden, and lowest caloric intake occurred during the blood count nadir. Higher melphalan concentrations correlated with more dysgeusia and poorer caloric intake. Future studies will aim to modulate melphalan exposure by PK-targeted dosing and characterize patient taste preferences to personalize diets for improved nutritional intake.

LAY SUMMARY

Taste changes after cancer treatments are very common. We used chemical gustometry (taste testing) to study taste changes and to better understand why patients with multiple myeloma experience this symptom after autologous hematopoietic cell transplantation. We found that taste testing was feasible, taste changes peaked when blood counts were lowest, and most patients recovered their taste by 100 days after transplantation. Taste changes correlated with lower food intake and with higher levels of chemotherapy in the body. Future work will focus on using personalized chemotherapy doses to reduce taste changes and to match patients' individual taste preferences with their diets.

Taste perception and food preferences in patients with diabetic foot ulcers before and after hyperbaric oxygen therapy

Objective

The aim of the study was to evaluate the effect of hyperbaric oxygen therapy (HBOT) on taste perception and food preferences in patients with diabetic foot ulcers.

Methods

The study involved 75 healthy people (Group C) and 23 patients with diabetic foot ulcers before HBOT (Group Db) and after 25–30 HBOT treatments (Group Da) (2.5 ATA, 87 min). The sip and spit method was used to examine the taste perception for 5 basic flavours. Food preferences were studied using photographs of dishes.

Results

The recognition thresholds in Group C were lower than in Group Db for 5 basic flavours. The taste intensity in Group C was higher than in Group Db for: 0.1% and 1.0% monosodium glutamate, 0.02% citric acid, and 0.002% quinine hydrochloride. The hedonic response in Group C was more negative than in Group Db for: 0.18% sodium chloride, 0.3% monosodium glutamate and 0.1% citric acid. The pleasure derived from eating in Group C was lower than in Group Db for sour and salty products. The recognition thresholds in Group Db were higher than in Group Da for umami and sour. The taste intensity in Group Db was lower than in Group Da for: 0.1%, 0.3% and 1.0% monosodium glutamate. The pleasure derived from eating in Group Db was higher than in Group Da for chocolate and crisps.

Conclusions

In people with diabetic foot ulcers, an impaired all 5 basic tastes occurred with different food preferences compared to healthy people. HBOT causes beneficial changes resulting in increased sensitivity to umami and sour taste as well as a decrease in the pleasure derived from eating chocolate and crisps.

Relationship between subjective taste sensations and taste strip test in patients with taste disorders with and without burning mouth syndrome

Background/purpose

Both subjective and objective evaluations are required to assess taste function. Evaluation of taste function has important clinical significances in patients with burning mouth syndrome (BMS) due to pain-taste interactions. The purpose of this study was to investigate the relationship between subjective and objective taste evaluations in patients with taste disorders based on the presence of BMS.

Materials and methods

Fifty–one patients with taste disturbances were included. The patients completed questionnaires on subjective taste sensations. The taste strip test was performed to examine objective taste function. The patients were divided into two groups: subjects with BMS (n = 24, 3 males and 21 females) and without BMS (n = 27, 8 males and 19 females).

Results

Significant differences were not observed in age, age distribution, and gender distribution between the groups. There were no significant differences in self-reported taste abilities based on the presence of BMS. However, the taste strip test showed higher correct answer rates for bitterness (P = 0.027) in the patients with BMS. In addition, a significant difference (P = 0.034) was observed in the distribution of objective types of taste disorders between the groups. A significant correlation between the subjective and objective evaluation results was observed only in patients with BMS.

Conclusion

In patients with taste disorders, patients with BMS had significant correlations between subjective and objective evaluations and different distributions in the types of taste disorders compared with those without BMS. The presence or absence of BMS should be evaluated in the diagnosis and management of taste disorders.

Olfactory Dysfunction in Aging African American and Caucasian Men With HIV: A Pilot Study

ABSTRACT

As people age with HIV, olfactory dysfunctions may become more pronounced, especially for African Americans who are predisposed to declines in olfaction. In this cross-sectional study, 34 middle-age and older African American and 17 Caucasian men living with HIV were administered two objective olfactory measures (UPSIT). In the Smell Threshold Test, compared to the HIV-negative age norms, adults living with HIV were significantly less able to detect a lower threshold smell. In the University of Pennsylvania Smell Identification Test, compared to the HIV-negative age norms, adults living with HIV were significantly less able to correctly identify odors; furthermore, using such norms, African Americans with HIV were less likely to correctly identify odors compared to Caucasians with HIV. Since the literature indicates that African Americans have a stronger attraction for salty and sweet foods, such olfactory dysfunction may contribute to poor eating habits, potentially predisposing this population to additional health problems.

Therapeutic diminution of Interleukin-10 with intranasal theophylline administration in hyposmic patients

OBJECTIVE

To determine changes in nasal mucus Interleukin-10 (IL-10) before and after intranasal theophylline treatment in hyposmic patients, and the relationship of these changes to orally administered theophylline treatment.

DESIGN

IL-10 was measured in nasal mucus samples of 17 normal subjects and 39 patients with hyposmia of multiple etiologies by use of a sensitive spectrophotometric ELISA assay. Hyposmia is defined clinically by standardized evaluation of impaired olfactometry, as well as subjectively self reported by the patient.

RESULTS

Prior to treatment, IL-10 levels in nasal mucus were increased in hyposmic patients compared to controls. Following intranasal theophylline administration, over half of treated patients experienced a decrease of nasal mucus IL-10 toward control levels, correlated with a significant improvement in taste and smell function. Patients who increased with intranasal administration, similar to previously reported oral administration, showed no significant improvement in taste or smell function.

CONCLUSIONS

Nasal mucus IL-10 decreased in patients treated with intranasal theophylline. Mechanisms of action include phosphodiesterase and nuclear factor kappa-B inhibition, correlated with an improvement in both olfaction and gustation. IL-10 is induced by therapeutic and systemic administration of theophylline as with oral dosage, but reduced by lower and localized treatment.

Future foods: Alternative proteins, food architecture, sustainable packaging, and precision nutrition

There are numerous challenges facing the modern food and agriculture industry that urgently need to be addressed, including feeding a growing global population, mitigating and adapting to climate change, decreasing pollution, waste, and biodiversity loss, and ensuring that people remain healthy. At the same time, foods should be safe, affordable, convenient, and delicious. The latest developments in science and technology are being deployed to address these issues. Some of the most important elements within this modern food design approach are encapsulated by the MATCHING model: Meat-reduced; Automation; Technology-driven; Consumer-centric; Healthy; Intelligent; Novel; and Globalization. In this review article, we focus on four key aspects that will be important for the creation of a new generation of healthier and more sustainable foods: emerging raw materials; structural design principles for creating innovative products; developments in eco-friendly packaging; and precision nutrition and customized production of foods. We also highlight some of the most important new developments in science and technology that are being used to create future foods, including food architecture, synthetic biology, nanoscience, and sensory perception.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2022.2033683.

A clinical survey on patients with taste disorders in Japan: A comparative study

OBJECTIVE

To investigate changes in the clinical state of taste disorders between 1990, 2003, and 2019 using the same methodology as that in previous studies.

MATERIALS AND METHODS

In June 2019, we mailed a questionnaire to 1100 otolaryngologists belonging to the Japan Society of Stomato-pharyngology and investigated three question categories: "Institution", "Number of patients for 3 months", and "Treatment". In addition, we analyzed some results by the class of institution.

RESULTS

The rate of patients who complained of taste disorders in the 2019 survey (220/100,000 persons/year) was twice that of the 1990 survey (110/100,000 persons/year), and slightly higher than that of the 2003 survey (192/100,000 persons/year). The rate of female patients was higher than that of male patients in all age groups. The number of patients was correlated with age up to 70 years of age in both genders. The rates of performing taste tests to assess taste function in the 2019 survey were significantly decreased compared with a 2003 survey (electrogustometry: p<0.001, filter paper disk method: p<0.05 in university). The rate of examination of the serum zinc in the 2019 survey was increased compared with the 1990 survey (p<0.001). Zinc oral therapy was used for the treatment of taste disorders in 239/299 (79.9%) patients/institutes for 3 months. In addition, 213 institutions (69.6%) answered that zinc oral therapy was efficacious for taste disorders.

CONCLUSION

The patients who complained of taste disorder have increased. The zinc administration is an appropriate clinical treatment for taste disorders in Japan. To enhance treatment for taste disorders, simpler methods for assessing taste function need to be developed, and the pathological mechanisms of taste disorders other than zinc deficiency need to be clarified.

Gustatory Function and Salivary Flow Rate in Healthy Adults

OBJECTIVES/HYPOTHESIS

In this study, we assessed gustatory function and whole-mouth saliva in healthy adults and investigated the association between gustatory function, salivary flow rate (SFR), and dry mouth.

STUDY DESIGN

Descriptive clinical study.

METHODS

We recruited 413 participants who reported a normal sense of smell-taste, comprising 206 females and 207 males with an age range of 19 to 80 years. Taste scores were obtained using whole-mouth tests to evaluate the gustatory function, SFR was assessed using the spitting method, and dry mouth was measured with the visual analog scale.

RESULTS

The total taste score (TTS) and SFR were significantly negatively correlated with age (r_taste  = -0.522, P < .001; r_SFR  = -0.200, P < .001): TTS was significantly lower after the age of 50 and SFR decreased significantly after age 65. Women exhibited a significantly higher TTS than men (P < .001). However, there was no effect of sex on SFR. Dry mouth was negatively correlated with TTS (r = -0.223, P < .01) and SFR (r = -0.218, P < .01). Multiple regression analysis showed the independent variables of age, sex, and dry mouth predicted 34% of the variation in taste, while the independent variables of age and dry mouth predicted 6.1% of the variation in whole-mouth saliva. TTS was not significantly correlated with the SFR in healthy adults (r = 0.094, P = .056).

CONCLUSIONS

Age and dry mouth are important factors affecting gustatory function and whole-mouth saliva, with women exhibiting better taste sensitivity than men. Furthermore, there is no direct correlation between SFR and gustatory function in healthy adults.

LEVEL OF EVIDENCE

3 Laryngoscope, 2021.

Dysgeusia: A review in the context of COVID-19

Background

Taste disorders in general, and dysgeusia in particular, are relatively common disorders that may be a sign of a more complex acute or chronic medical condition. During the COVID-19 pandemic, taste disorders have found their way into the realm of general as well as specialty dentistry, with significance in screening for patients who potentially may have the virus.

Types of Studies Reviewed

The authors searched electronic databases (PubMed, Embase, Web of Science, Google Scholar) for studies focused on dysgeusia, ageusia, and other taste disorders and their relationship to local and systemic causes.

Results

The authors found pertinent literature explaining the normal physiology of taste sensation, proposals for suggested new tastes, presence of gustatory receptors in remote tissues of the body, and etiology and pathophysiology of taste disorders, in addition to the valuable knowledge gained about gustatory disorders in the context of COVID-19. Along with olfactory disorders, taste disorders are one of the earliest suggestive symptoms of COVID-19 infection.

Conclusions

Gustatory disorders are the result of local or systemic etiology or both. Newer taste sensations, such as calcium and fat tastes, have been discovered, as well as taste receptors that are remote from the oropharyngeal area. Literature published during the COVID-19 pandemic to date reinforces the significance of early detection of potential patients with COVID-19 by means of screening for recent-onset taste disorders.

Practical Implications

Timely screening and identification of potential gustatory disorders are paramount for the dental care practitioner to aid in the early diagnosis of COVID-19 and other serious systemic disorders.

Presence of gustatory and olfactory dysfunction in the time of the COVID-19 pandemic

BACKGROUND

The unexpected outbreak of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused more than 49 million cases and an estimated 2,000,000 associated deaths worldwide. In Germany, there are currently more than 2,000,000 laboratory-confirmed coronavirus disease 2019 (COVID-19) cases including 51,800 deaths. However, regional differences also became apparent and with the second wave of infections, the detailed characterization of COVID-19 patients is crucial to early diagnosis and disruption of chains of infections.

METHODS

Handing out detailed questionnaires to all individuals tested for COVID-19, we evaluated the clinical characteristics of negative and positive tested individuals. Expression of symptoms, symptom duration and association between predictor variables (i.e. age, gender) and a binary outcome (olfactory and gustatory dysfunction) were assessed.

RESULTS

Overall, the most common symptoms among individuals who tested positive for SARS-CoV-2 were fatigue, headache, and cough. Olfactory and gustatory dysfunction were also reported by many SARS-CoV-2 negative individuals, more than 20% of SARS-CoV-2 negative tested individuals in our study reported olfactory and gustatory dysfunction. Independent of SARS-CoV-2 status, more females displayed symptoms of gustatory (29.8%, p = 0.0041) and olfactory dysfunction (22.9%, p = 0.0174) compared to men.

CONCLUSIONS

Bringing early SARS-CoV-2 tests to the populations at risk must be a main focus for the upcoming months. The reliability of olfactory and gustatory dysfunction in COVID-19 negative tested individuals requires deeper investigation in the future.

Pathophysiology and possible treatments for olfactory-gustatory disorders in patients affected by COVID-19

SARS-CoV-2 infects host cells mainly through the interaction between the virus's Spike protein and the viral receptors namely Angiotensin-Converting Enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). Both are highly expressed in the gastrointestinal tract, in the nasal and bronchial epithelium, as well as in the type II alveolar epithelial cells. The aim of this review is to report the evidences from the scientific literature on the pathophysiology and the available treatments for olfactory-gustatory disorders in patients with COVID-19. The mechanisms involved in these disorders are still unclear and studies on specific therapies are scarce. However, it has been hypothesized that a decrease in the sensitivity of the sensory neurons as well as the co-expression of ACE2 and TMPRSS2 in the alveolar epithelial cells are the main causes of olfactory-gustatory disorders. The possible mechanisms described in the literature for changes in taste perception in patients with COVID-19 include olfactory disorders and a competitive activity of COVID-19 on ACE2 receptors in the taste buds. In addition, SARS-CoV-2 can bind to sialic acid receptors in the taste buds. In general, evidences show that there is no specific treatment for olfactory-taste disorders induced by SARS-CoV-2, even though some treatments have been used and have shown some promising results, such as olfactory training, intranasal application of sodium citrate and vitamin A, as well as systemic use of omega-3 and zinc. Corticosteroids have also been used as a pharmacological approach to treat patients with olfactory dysfunction with some contradictory results. The knowledge of the mechanisms by which SARS-CoV-2 influences the sensory systems and how effective therapies can treat the loss of smell and taste will have important implications on the understanding and clinical management of olfactory-taste disorders.

Data-science based analysis of perceptual spaces of odors in olfactory loss

Diminished sense of smell impairs the quality of life but olfactorily disabled people are hardly considered in measures of disability inclusion. We aimed to stratify perceptual characteristics and odors according to the extent to which they are perceived differently with reduced sense of smell, as a possible basis for creating olfactory experiences that are enjoyed in a similar way by subjects with normal or impaired olfactory function. In 146 subjects with normal or reduced olfactory function, perceptual characteristics (edibility, intensity, irritation, temperature, familiarity, hedonics, painfulness) were tested for four sets of 10 different odors each. Data were analyzed with (i) a projection based on principal component analysis and (ii) the training of a machine-learning algorithm in a 1000-fold cross-validated setting to distinguish between olfactory diagnosis based on odor property ratings. Both analytical approaches identified perceived intensity and familiarity with the odor as discriminating characteristics between olfactory diagnoses, while evoked pain sensation and perceived temperature were not discriminating, followed by edibility. Two disjoint sets of odors were identified, i.e., d = 4 “discriminating odors” with respect to olfactory diagnosis, including cis-3-hexenol, methyl salicylate, 1-butanol and cineole, and d = 7 “non-discriminating odors”, including benzyl acetate, heptanal, 4-ethyl-octanoic acid, methional, isobutyric acid, 4-decanolide and p-cresol. Different weightings of the perceptual properties of odors with normal or reduced sense of smell indicate possibilities to create sensory experiences such as food, meals or scents that by emphasizing trigeminal perceptions can be enjoyed by both normosmic and hyposmic individuals.

A Systematic Review of the Neuropathologic Findings of Post-Viral Olfactory Dysfunction: Implications and Novel Insight for the COVID-19 Pandemic

BACKGROUND

Post-viral olfactory dysfunction is a common cause of both short- and long-term smell alteration. The coronavirus pandemic further highlights the importance of post-viral olfactory dysfunction. Currently, a comprehensive review of the neural mechanism underpinning post-viral olfactory dysfunction is lacking.

OBJECTIVES

To synthesize the existing primary literature related to olfactory dysfunction secondary to viral infection, detail the underlying pathophysiological mechanisms, highlight relevance for the current COVID-19 pandemic, and identify high impact areas of future research.

METHODS

PubMed and Embase were searched to identify studies reporting primary scientific data on post-viral olfactory dysfunction. Results were supplemented by manual searches. Studies were categorized into animal and human studies for final analysis and summary.

RESULTS

A total of 38 animal studies and 7 human studies met inclusion criteria and were analyzed. There was significant variability in study design, experimental model, and outcome measured. Viral effects on the olfactory system varies significantly based on viral substrain but generally include damage or alteration in components of the olfactory epithelium and/or the olfactory bulb.

CONCLUSIONS

The mechanism of post-viral olfactory dysfunction is highly complex, virus-dependent, and involves a combination of insults at multiple levels of the olfactory pathway. This will have important implications for future diagnostic and therapeutic developments for patients infected with COVID-19.

COVID 19-Induced Smell and Taste Impairments: Putative Impact on Physiology

Smell and taste impairments are recognized as common symptoms in COVID 19 patients even in an asymptomatic phase. Indeed, depending on the country, in up to 85-90% of cases anosmia and dysgeusia are reported. We will review briefly the main mechanisms involved in the physiology of olfaction and taste focusing on receptors and transduction as well as the main neuroanatomical pathways. Then we will examine the current evidences, even if still fragmented and unsystematic, explaining the disturbances and mode of action of the virus at the level of the nasal and oral cavities. We will focus on its impact on the peripheral and central nervous system. Finally, considering the role of smell and taste in numerous physiological functions, especially in ingestive behavior, we will discuss the consequences on the physiology of the patients as well as management regarding food intake.

Alteration, Reduction and Taste Loss: Main Causes and Potential Implications on Dietary Habits

Our sense of taste arises from the sensory information generated after compounds in the oral cavity and oropharynx activate taste receptor cells situated on taste buds. This produces the perception of sweet, bitter, salty, sour, or umami stimuli, depending on the chemical nature of the tastant. Taste impairments (dysgeusia) are alterations of this normal gustatory functioning that may result in complete taste losses (ageusia), partial reductions (hypogeusia), or over-acuteness of the sense of taste (hypergeusia). Taste impairments are not life-threatening conditions, but they can cause sufficient discomfort and lead to appetite loss and changes in eating habits, with possible effects on health. Determinants of such alterations are multiple and consist of both genetic and environmental factors, including aging, exposure to chemicals, drugs, trauma, high alcohol consumption, cigarette smoking, poor oral health, malnutrition, and viral upper respiratory infections including influenza. Disturbances or loss of smell, taste, and chemesthesis have also emerged as predominant neurological symptoms of infection by the recent Coronavirus disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus strain 2 (SARS-CoV-2), as well as by previous both endemic and pandemic coronaviruses such as Middle East Respiratory Syndrome Coronavirus (MERS-CoV) and SARS-CoV. This review is focused on the main causes of alteration, reduction, and loss of taste and their potential repercussion on dietary habits and health, with a special focus on the recently developed hypotheses regarding the mechanisms through which SARS-CoV-2 might alter taste perception.

Relationships between subjective taste sensations and electrogustometry findings in patients with taste disorders

This study aimed to examine the relationships between subjective taste sensations and electrogustometry (EGM) findings in patients with taste disturbances according to the presence of burning mouth (BM) symptoms. Forty-six patients were included and asked to complete a questionnaire that contained questions on subjective taste sensations for the four basic taste qualities and the pattern of taste disorders such as ageusia, hypogeusia and dysgeusia. EGM was performed to measure detection thresholds. To examine the influence of BM symptoms, patients were divided into two groups: patients with and without BM symptoms. The patients consisted of 11 men and 35 women. The group without BM symptoms (n=26) had significantly lower degrees of subjective taste sensations for all taste qualities and higher correlation levels between subjective taste sensations and EGM thresholds than the group with BM symptoms (n=20). The patterns of taste disorders also showed more significant associations with the levels of subjective taste sensations in the patients without BM symptoms compared with those with BM symptoms. In conclusion, patients with taste disorders without BM symptoms had more severe taste disturbances than those with BM symptoms. The pathophysiology of taste disturbances differs according to the presence or absence of BM symptoms.

A Systematic Review and Meta-Analysis of Taste Dysfunction in Chronic Rhinosinusitis

OBJECTIVES

Patients with chronic rhinosinusitis (CRS) often describe alterations in sense of taste. These complaints have historically been attributed to olfactory dysfunction; however, there is evidence of direct, objective, gustatory disturbances in the setting of CRS that are not thoroughly characterized. This study sought to investigate and summarize gustatory dysfunction experienced by patients with CRS.

METHODS

PubMed, EMBASE, Cochrane Library, Web of Science, and Scopus databases were reviewed following PRISMA guidelines. English language, original studies investigating objective taste in adult patients with CRS were included. A meta-analysis with inverse variance, random-effects model was performed.

RESULTS

Of 2750 studies screened, 11 articles with 471 unique patients were included. Patients with CRS exhibit worse gustatory function compared to healthy controls (standardized mean difference 0.94 [95% CI, 0.44-1.45]). Hypogeusia was identified in 32/95 (33.7%) patients from three studies that used methods with a validated definition of hypogeusia. Older age, male gender, and smoking history were associated with taste dysfunction, while objective gustatory and olfactory dysfunction were not correlated. Subjective taste and quality of life measures were also not associated with objective taste. The impact of sinus surgery on objective taste is unclear.

CONCLUSION

Approximately 34% of patients with CRS experience hypogeusia. Neither olfactory function nor subjective taste were associated with objective gustatory function. Given the substantial prevalence of taste dysfunction patients with CRS, there is significant potential for growth in understanding of pathogenesis, impact on quality of life, and potential treatment strategies of taste impairment in the CRS patient population.

LEVEL OF EVIDENCE

1 Laryngoscope, 131:482-489, 2021.

Heme as a Taste Molecule

PURPOSE OF REVIEW

The sense of taste has evolved to enable the identification of appropriate substances to consume, to acquire nutrients, and to avoid consuming potential toxins. Five basic taste classes have been recognized, although there may be others, including metallic taste, which have not been well defined. The purpose of this review was to survey available data from diverse sources to determine how much was known about the molecular basis for metallic taste.

RECENT FINDINGS

Metallic taste has been studied in the context of dysgeusia, primarily using non-heme iron as an inducer of metallic taste sensation. However, recent efforts by industry to develop plant-based meat substitutes have suggested that iron in the form of heme may be the main molecule underlying the taste of meat. Little work has been done on heme as a taste molecule. Data support a primary role for heme in metallic taste that may have evolved as part of a means to consume and preserve elemental iron for physiological needs.

Associations Among Taste Perception, Food Neophobia and Preferences in Type 1 Diabetes Children and Adolescents: A Cross-Sectional Study

Type 1 diabetes (T1D) is one of the most common systemic diseases in childhood which predisposes the patient to serious short-term and long-term complications, affecting all body systems. Taste and olfactory impairments were first described a long time ago in adult patients affected by diabetes (both type 1 and type 2 diabetes). However, studies evaluating taste perception, behavioral attitudes (e.g., food neophobia), and preferences toward foods in children and adolescents affected by T1D are globally lacking. Therefore, the purpose of this study was to assess taste sensitivity, food neophobia, and preferences among children and adolescents affected by T1D and healthy controls in a cross-sectional study. T1D patients presented a significantly lower ability in general to correctly identify taste qualities, especially bitter and sour tastes. Moreover, they were characterized by fewer fungiform papillae compared to controls, as well as a lower responsiveness to the bitter compound 6-n-propylthiouracil (PROP). There were no significant differences in food neophobia scores between the two groups, but differences were observed in the mean hedonic ratings for some product categories investigated. Diabetic patients showed a greater liking for certain type of foods generally characterized by sourness and bitterness, an observation probably linked to their impaired ability to perceive taste stimuli, e.g., sourness and bitterness. These results may help to enhance the understanding of these relationships in populations with elevated diet-related health risks.

The Use of Imaging to Detect Intracranial Tumors in Idiopathic Olfactory Dysfunction: A Systematic Review

Objectives

To review the literature regarding the use of intracranial imaging as a screening tool for idiopathic olfactory loss (IOL) and to review the incidence of identifying a sinonasal or intracranial neoplasm as a result of intracranial imaging.

Methods

A systematic review of published English-language literature was performed using PubMed, Ovid MEDLINE, Scopus, and Cochrane databases.

Results

Of the 694 available abstracts, 5 met inclusion criteria for this review. Out of 470 eligible patients, intracranial imaging identified tumors causing IOL in 8 patients (1.7%). Tumor detection rates ranged from 0% to 4.9%. Of the 470 eligible patients, intracranial imaging detected intracranial or sinonasal pathology, excluding tumors, causing IOL in 53 patients (11%). The findings ranged from 0.77% to 23%. Of the 604 eligible IOL patients, 470 (81%) underwent intracranial imaging, ranging from 53% to 100%.

Conclusions

In most cases, diagnostic imaging in IOL patients is frequently ordered. This study finds computed tomography or magnetic resonance imaging to be an important recommendation given to all patients with IOL. Although the overall rate of detecting tumor from diagnostic imaging is low, it is important to offer diagnostic imaging to this subset of patients to avoid missing tumors at an early stage.

Remission of anosmia in a patient receiving chiropractic care: A case report

OBJECTIVE

To chronicle the remission of anosmia in a 79-year-old female receiving chiropractic care using the Activator Methods Chiropractic Technique (AMCT) protocol.

CLINICAL FEATURES

A 79-year-old white female with a 4-year history of medically diagnosed anosmia. Postural alterations, reduction in cervical ranges of motion (ROM), and absent cranial nerve I function were found in conjunction with vertebral subluxation throughout the spine and mild to severe degenerative changes throughout the spine present on radiographic studies.

INTERVENTION & OUTCOMES

Chiropractic care using AMCT was provided for the assessment and correction of vertebral subluxations. The patient reported subjective improvement in olfaction, physical functioning and life enjoyment, and demonstrated objective improvement in posture, cervical ROM, cranial nerve I function.

CONCLUSION

A course of chiropractic care, following the AMCT protocol, was associated with remission of anosmia.

A machine-learned analysis suggests non-redundant diagnostic information in olfactory subtests

BACKGROUND

The functional performance of the human sense of smell can be approached via assessment of the olfactory threshold, the ability to discriminate odors or the ability to identify odors. Contemporary clinical test batteries include all or a selection of these components, with some dissent about the required number and choice.

METHODS

Olfactory thresholds, odor discrimination and odor identification scores were available from 10,714 subjects (3662 with anomia, 4299 with hyposmia, and 2752 with normal olfactory function). To assess, whether the olfactory subtests confer the same information or each subtest confers at least partly non-redundant information relevant to the olfactory diagnosis, we compared the diagnostic accuracy of supervised machine learning algorithms trained with the complete information from all three subtests with that obtained when performing the training with the information of only two or one subtests.

RESULTS

The training of machine-learned algorithms with the full information about olfactory thresholds, odor discrimination and odor identification from 2/3 of the cases, resulted in a balanced olfactory diagnostic accuracy of 98% or better in the 1/3 remaining cases. The most pronounced decrease in the balanced accuracy, to approximately 85%, was observed when omitting olfactory thresholds from the training, whereas omitting odor discrimination or identification was associated with smaller decreases (balanced accuracies approximately 90%).

CONCLUSIONS

Results support partly non-redundant contributions of each olfactory subtest to the clinical olfactory diagnosis. Olfactory thresholds provided the largest amount of non-redundant information to the olfactory diagnosis.

Evaluation of idiopathic olfactory loss with chemosensory event-related potentials and magnetic resonance imaging

Background

Idiopathic olfactory loss (IOL) accounts for a sizable fraction of olfactory dysfunction, but very little is known about its etiology and electrophysiological changes in the olfactory pathway.

Methods

We analyzed the physiology of IOL using chemosensory event‐related potentials (ERPs) (olfactory and trigeminal: oERP and tERP) and olfactory pathway magnetic resonance imaging (MRI) measured in adult patients with IOL and healthy controls. Subjective olfactory function was measured by Toyota and Takagi (T&T) olfactometry and Sniffin’ Sticks (SS).

Results

Olfactory function was worse in patients with IOL compared to controls (T&T, p < 0.001; SS, p < 0.001). oERPs could be evoked in 17 IOL patients. Signals in these patients showed lower amplitude in the N₁ and P₂ waves than controls (p < 0.05 for both), but there were no difference in latency between the 2 groups (p > 0.05). tERP were detected in all patients and controls; there were no differences in latency and nor amplitude between the 2 groups (p > 0.05). The olfactory bulb (OB) volume was significantly smaller in the IOL group than controls (p < 0.001), but there was no difference in the olfactory sulcus depth between groups (p > 0.05). Better olfactory function was associated with increasing magnitude of N₁ amplitude in oERPs (p < 0.05) and increasing OB volume (p < 0.05).

Conclusion

IOL patients show neurophysiologic deficits and some anatomic differences compared to healthy controls.

Effect of Intranasal Insulin on Olfactory Recovery in Patients with Hyposmia: A Randomized Clinical Trial

Objective

Hyposmia is a sensorial disorder in which patients have a reduced sense of smell. However, there are no effective regimens for the management of this disorder. Therefore, the aim of this study is to evaluate the therapeutic effect of intranasal insulin on olfactory recovery in patients with hyposmia.

Study Design

This is a double-blinded, randomized controlled trial.

Setting

Intervention.

Subjects and Methods

This study was administered on 38 patients with hyposmia according to the inclusion and exclusion criteria. Patients were randomly divided into 2 parallel groups. The intervention and placebo groups underwent endoscopic placement of intranasal insulin gel foam (40 IU) and saline-soaked gel foam into the olfactory cleft, respectively. The procedure was performed twice a week for 4 weeks with butanol threshold testing initially and 4 weeks after treatment.

Results

The Connecticut Chemosensory Clinical Research Center score in the intervention group was significantly higher compared to that of the placebo group after 4 weeks ( P = .01). Moreover, no adverse effects were reported in both groups.

Conclusion

Our findings indicated that intranasal insulin (40 IU) administration may trigger the improvement in the olfactory sense and also appears to be free of significant adverse events in this small cohort. However, due to limited research regarding this topic, further studies using a larger population are required.

Interventions for managing taste disturbances

BACKGROUND

The sense of taste is very much essential to the overall health of an individual. It is a necessary component to enjoy one's food, which in turn provides nutrition to an individual. Any disturbance in taste perception can hamper quality of life in such patients by influencing their appetite, body weight and psychological well-being. Taste disorders have been treated using different modalities of treatment and there is no consensus for the best intervention. Hence this Cochrane Review was undertaken. This is an update of the Cochrane Review first published in November 2014.

OBJECTIVES

To assess the effects of interventions for the management of patients with taste disturbances.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 4 July 2017); the Cochrane Central Register of Controlled Trials (CENTRAL; 2017 Issue 6) in the Cochrane Library (searched 4 July 2017); MEDLINE Ovid (1946 to 4 July 2017); Embase Ovid (1980 to 4 July 2017); CINAHL EBSCO (1937 to 4 July 2017); and AMED Ovid (1985 to 4 July 2017). The US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for trials. Abstracts from scientific meetings and conferences were searched on 25 September 2017. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing any pharmacological agent with a control intervention or any non-pharmacological agent with a control intervention. We also included cross-over trials in the review.

DATA COLLECTION AND ANALYSIS

Two pairs of review authors independently, and in duplicate, assessed the quality of trials and extracted data. Wherever possible, we contacted trial authors for additional information. We collected adverse events information from the trials.

MAIN RESULTS

We included 10 trials (581 participants), nine of which we were able to include in the quantitative analyses (566 participants). We assessed three trials (30%) as having a low risk of bias, four trials (40%) at high risk of bias and three trials (30%) as having an unclear risk of bias. We only included studies on taste disorders in this review that were either idiopathic, or resulting from zinc deficiency or chronic renal failure.Of these, nine trials with 544 people compared zinc supplements to placebo for patients with taste disorders. The participants in two trials were children and adolescents with respective mean ages of 10 and 11.2 years and the other seven trials had adult participants. Out of these nine, two trials assessed the patient-reported outcome for improvement in taste acuity using zinc supplements (risk ratio (RR) 1.40, 95% confidence interval (CI) 0.94 to 2.09; 119 participants, very low-quality evidence). We meta-analysed for taste acuity improvement using objective outcome (continuous data) in idiopathic and zinc-deficient taste disorder patients (standardised mean difference (SMD) 0.44, 95% CI 0.23 to 0.65; 366 participants, three trials, very low-quality evidence). We also analysed one cross-over trial separately using the first half of the results for taste detection (mean difference (MD) 2.50, 95% CI 0.93 to 4.07; 14 participants, very low-quality evidence), and taste recognition (MD 3.00, 95% CI 0.66 to 5.34; 14 participants, very low-quality evidence). We meta-analysed taste acuity improvement using objective outcome (dichotomous data) in idiopathic and zinc-deficient taste disorder patients (RR 1.42, 95% 1.09 to 1.84; 292 participants, two trials, very low-quality evidence). Out of the nine trials using zinc supplementation, four reported adverse events like eczema, nausea, abdominal pain, diarrhoea, constipation, decrease in blood iron, increase in blood alkaline phosphatase, and minor increase in blood triglycerides.One trial tested taste discrimination using acupuncture (MD 2.80, 95% CI -1.18 to 6.78; 37 participants, very low-quality evidence). No adverse events were reported in the acupuncture trial.None of the included trials could be included in the meta-analysis for health-related quality of life in taste disorder patients.

AUTHORS' CONCLUSIONS

We found very low-quality evidence that was insufficient to conclude on the role of zinc supplements to improve taste acuity reported by patients and very low-quality evidence that zinc supplements improve taste acuity in patients with zinc deficiency/idiopathic taste disorders. We did not find any evidence to conclude the role of zinc supplements for improving taste discrimination, or any evidence addressing health-related quality of life due to taste disorders.We found very low-quality evidence that is not sufficient to conclude on the role of acupuncture for improving taste discrimination in cases of idiopathic dysgeusia (distortion of taste) and hypogeusia (reduced ability to taste). We were unable to draw any conclusions regarding the superiority of zinc supplements or acupuncture as none of the trials compared these interventions.

Association between Sex, CD4 Cell Counts, Antiretroviral Medications, and Olfactory and Gustatory Functions of HIV-Infected Adults

Objective To investigate the olfactory and gustatory functions of human immunodeficiency virus (HIV)-infected adults in Ibadan, Nigeria. Study Design A cross-sectional study of olfactory and gustatory functions of HIV-infected adults between March 2015 and December 2015. Setting Tertiary health institution. Subjects and Methods A structured questionnaire was administered to participants to obtain relevant sociodemographic and clinical information. Participants' nadir and most recent CD4 cell count and viral loads were obtained from their medical records. Participants' body mass indices were determined, and each subjectively rated their olfactory and gustatory performances. Objective olfactory and gustatory functions were determined using validated "Sniffin' Sticks" and "Taste Strips" impregnated with 4 different concentrations of sucrose, quinine hydrochloride, sodium chloride, and citric acid. Results In total, 135 HIV-infected adults, comprising 41 (30.4%) men and 94 (69.6%) women, were evaluated. Their ages ranged from 20 to 70 years, mean 43.4 ± 10.4 years. Participants were on highly active antiretroviral therapy for a mean duration of 75.8 ± 36.9 months. The proportions of male participants in HIV stages 1, 2, and 3 were 18 (43.9%), 19 (46.3%), and 4 (9.8%), respectively, while female participants were 46 (48.9%), 41 (43.6%), and 7 (7.4%), respectively. Participants' mean olfactory threshold, discrimination, identification, and TDI scores were 8.0 ± 4.9, 9.9 ± 4.7, 8.8 ± 4.5, and 26.7 ± 11.1, respectively, while total taste score was 25.1 ± 5.7. Conclusion HIV-infected adults have tendency to develop hyposmia and hypogeusia. These are worse with advanced stage of HIV infection.

Phantosmia and Dysgeusia following Endoscopic Transcribriform Approaches to Olfactory Groove Meningiomas

The endoscopic, endonasal transcribriform approach (EETA) is an important technique used to directly access the anterior skull base and is increasingly being used in the management of olfactory groove meningiomas (OGMs). As this approach requires removal of the cribriform plate and olfactory epithelium en route to the tumor, patients are anosmic postoperatively. Here, we report the development of phantosmia and dysgeusia in two patients who underwent EETAs for OGMs, which has not yet been reported in the literature. We hypothesize that phantosmia and dysgeusia may result from aberrant neuronal signals or misinterpretation centrally from the remaining distal portions of the olfactory and taste pathways. Since EETAs are newer than traditional open craniotomy-based techniques, reporting these outcomes will be important to appropriately counsel patients preoperatively.

Cerebral metabolic changes related to clinical parameters in idiopathic anosmic patients during olfactory stimulation: a pilot investigation

Idiopathic olfactory loss neural consequences have been studied especially by means of magnetic resonance imaging. Since other functional neuroimaging technique findings are lacking in the literature, present study used a validated ¹⁸F-2-fluoro-2-deoxy-D-glucose (FDG) functional positron emission tomography procedure under olfactory stimulation (OS) to assess brain changes in idiopathic anosmic patients (IAPs) in comparison with healthy subjects (HS). A voxel-based analysis between these groups was used to evaluate FDG uptake in the brain and perform a correlation analysis between metabolic responses and the Sniffin' stick test as well as intensity visuo-analogue scores and disease duration (DD). A significant relative decrease of glucose metabolism in the right and left frontal lobes, left insula, right parietal lobe, and left occipital, temporal and parietal lobes was found in IAPs during OS. The same condition resulted in a relative higher glucose metabolism in the right cerebellum in IAPs. Moreover, a negative correlation between DD and FDG uptake in the left temporo-parietal joint was found in IAPs. Such a correlation suggested a possible involvement of this area metabolic decrease in self-consciousness impairment, which is known to affect IAPs. Present preliminary functional results could be of interest to further deepen such neural impairments possibly useful for future perspective in pharmaceutical and rehabilitative protocols.

Improved smell function with increased nasal mucus sonic hedgehog in hyposmic patients after treatment with oral theophylline

PURPOSE

We previously demonstrated the presence of sonic hedgehog (Shh) in nasal mucus in normal subjects and in patients with smell loss (hyposmia). Nasal mucus Shh levels were found significantly diminished in untreated hyposmic patients of multiple etiologies. Since treatment with oral theophylline has been previously associated with improvement in smell function we wished to study if such treatment increased nasal mucus Shh as well as improved smell function in patients with hyposmia.

METHODS

Forty-four patients with hyposmia of several etiologies were evaluated for changes in hyposmia by subjective measurements of smell, taste and flavor perception and by olfactometry. Measurements of nasal mucus Shh were made in relationship to each set of sensory measurements. Patients were treated with oral theophylline at doses of 200-800mg for periods of 2-10months with sensory function, nasal mucus Shh and serum theophylline levels evaluated at these time intervals. Nasal mucus Shh measurements were made with a sensitive spectrophotometric ELISA assay and theophylline with a fluorometric assay.

RESULTS

There was consistent, significant improvement in subjective responses in smell, taste and flavor perception and in olfactometry associated with increased nasal mucus Shh and serum theophylline after theophylline treatment.

CONCLUSIONS

Improvement in smell function and in nasal mucus Shh was positively correlated in a dose-response relationship after treatment with oral theophylline. Results are consistent with a successful role for theophylline in improvement of smell function in hyposmic patients of multiple etiologies associated with increased nasal mucus Shh which can act as a biochemical marker for smell function.

Randomized Controlled Trial Demonstrating Cost-Effective Method of Olfactory Training in Clinical Practice: Essential Oils at Uncontrolled Concentration

OBJECTIVES

Published data examining the efficacy of olfactory training (OT) has used standardized concentrations of odorants and the Sniffin' Sticks testing method. Although well-validated, these methods are costly and time-intensive for the average otolaryngology practice. The purpose of our study was to evaluate the efficacy of using essential oils at random concentrations and the University of Pennsylvania Smell Test (UPSIT) for training and testing, and compare this with the existing data on OT.

STUDY DESIGN

Randomized Clinical TrialMethods: Patients presenting to a tertiary care rhinology center with subjective loss of smell and olfactory loss measured by UPSIT were randomized to OT or control for 6 months. Only patients with loss of smell greater than one-year duration, and loss associated with post-infectious and idiopathic etiologies were included. Baseline UPSIT was compared to 6-month UPSIT. An accepted 10% change or better was used to establish a significant improvement on UPSIT.

RESULTS

43 patients were enrolled. Eight patients were lost to follow-up, with a total of 35 completing the study. Age ranged from 39-71 with an average of 56. Of 19 patients in the OT group, 6 showed significant improvement (32%), while only two out of 16 patients (13%) in the control group improved. Increasing age and duration of loss were significantly correlated to lack of improvement.

CONCLUSION

Allowing patients to use random concentrations of essential oils to perform OT is as effective as published data using controlled concentrations of odorants for post-infectious and idiopathic olfactory loss.

LEVEL OF EVIDENCE

1b.

Disrupted Odor Perception

Olfactory loss is frequent. However, in public not many people complain of that, or they are even not (fully) aware of it. This indicates that it is possible to live a life without a sense of smell, albeit it is more dangerous, less pleasant, and food tastes much less interesting. Most common causes for smell loss are sinunasal disease (chronic rhinosinusitis with and without nasal polyps), acute infections of the upper airways, head trauma, and neurodegenerative disorders. In many people smell loss seems to be due to the aging process. Before treatment olfactory disorders are diagnosed according to cause with the medical history being a big portion of the diagnostic process. Olfactory disorders are in principle reversible, with a relatively high degree of spontaneous improvement in olfactory loss following infections of the upper respiratory tract. Medical treatment is according to cause. It also involves surgical approaches as well as conservative treatments including the use of corticosteroids, antibiotics, or smell training. Because today olfactory dysfunction seems to receive more attention than in previous years it can be expected that tomorrow we will have more specific and effective treatment options available.

A genetic marker of the ACKR1 gene is present in patients with Type II congenital smell loss who have type I hyposmia and hypogeusia

PURPOSE

Our previous study of Type II congenital smell loss patients revealed a statistically significant lower prevalence of an FY (ACKR1, formerly DARC) haplotype compared to controls. The present study correlates this genetic feature with subgroups of patients defined by specific smell and taste functions.

METHODS

Smell and taste function measurements were performed by use of olfactometry and gustometry to define degree of abnormality of smell and taste function. Smell loss was classified as anosmia or hyposmia (types I, II or III). Taste loss was similarly classified as ageusia or hypogeusia (types I, II or III). Based upon these results patient erythrocyte antigen expression frequencies were categorized by smell and taste loss with results compared between patients within the Type II group and published controls.

RESULTS

Comparison of antigen expression frequencies revealed a statistically significant decrease in incidence of an Fy^b haplotype only among patients with type I hyposmia and any form of taste loss (hypogeusia). In all other patient groups erythrocyte antigens were expressed at normal frequencies.

CONCLUSIONS

Data suggest that Type II congenital smell loss patients who exhibit both type I hyposmia and hypogeusia are genetically distinct from all other patients with Type II congenital smell loss. This distinction is based on decreased Fy^b expression which correlated with abnormalities in two sensory modalities (hyposmia type I and hypogeusia). Only patients with these two specific sensory abnormalities expressed the Fy^b antigen (encoded by the ACKR1 gene on the long arm of chromosome 1) at frequencies different from controls.

On the mechanism of smell loss in patients with Type II congenital hyposmia

BACKGROUND

Smell function has been initiated with theophylline treatment in 63% of patients with Type II congenital smell loss. Based upon a systematic evaluation of the protein components of nasal mucus we have demonstrated that interactions among four chemical moieties in nasal mucus may play significant roles in this initiation. Prior to treatment three of these moieties, cAMP, cGMP and sonic hedgehog (Shh), were significantly decreased in concentration whereas one of these moieties, TNFalpha, was increased in concentration. The mechanism(s) responsible for initiation of smell function in these patients, not immediately apparent, may depend upon understanding interactions among these moieties.

METHODS

Measurements of cAMP, cGMP, Shh and TNFalpha in nasal mucus by specific spectrophotometric immunoassays before and after treatment with theophylline.

RESULTS

Before theophylline treatment cAMP, cGMP and Shh in nasal mucus, which act as growth factors to support olfactory receptor function, were significantly decreased below normal levels whereas TNFalpha which acts as a "death factor" to inhibit olfactory receptor function was significantly increased above normal. After theophylline treatment cAMP, cGMP and Shh increased significantly whereas TNFalpha decreased significantly.

CONCLUSIONS

These results indicate that there are specific biochemical changes associated with smell loss in patients with Type II congenital smell loss and that correction of these biochemical changes are associated with initiation of smell function in these patients. Understanding these relationships play an important role in understanding receptor action in smell function.

Hypothyroidism Affects Olfactory Evoked Potentials

Background. Objective electrophysiological methods for investigations of the organ of smell consist in recordings of olfactory cortex responses to specific, time restricted odor stimuli. In hypothyroidism have impaired sense of smell. Material and Methods. Two groups: control of 31 healthy subjects and study group of 21 with hypothyroidism. The inclusion criterion for the study group was the TSH range from 3.54 to 110 μIU/mL. Aim. Assessment of the latency time of evoked responses from the olfactory nerve N1 and the trigeminal nerve N5 using two smells of mint and anise in hypothyroidism. Results. The smell perception in subjective olfactory tests was normal in 85% of the hypothyroid group. Differences were noticed in the objective tests. The detailed intergroup analysis of latency times of recorded cortical responses P_N5 and P_N1 performed by means between the groups of patients with overt clinical hypothyroidism versus subclinical hypothyroidism demonstrated a significant difference (p < 0.05) whereas no such differences were found between the control group versus subclinical hypothyroidism group (p > 0.05). Conclusion. We can conclude that registration of cortex potentials at irritation of olfactory and trigeminal nerves offers possibilities for using this method as an objective indicator of hypothyroidism severity and prognostic process factor.

Alterations in taste perception as a result of hyperbaric oxygen therapy

The present study evaluates the effect of hyperbaric oxygen therapy on taste sensitivity, hedonic perception of taste, and food preferences. The studied groups included 197 people in total (79 in the study group; 118 in the control group). All patients from the study group were treated with hyperbaric oxygen therapy due to chronic non-healing wounds. The control group consisted of healthy people, who did not receive hyperbaric oxygen therapy. The taste intensity, recognition thresholds, and hedonic perception were examined using gustatory tests. The aqueous solutions of sucrose for sweet, sodium chloride for salty, citric acid for sour, quinine hydrochloride for bitter, and monosodium glutamate for umami taste were used. The participants fulfilled the questionnaire to examine pleasure derived from eating certain types of dishes. Gustatory tests and analyses of the pleasure derived from eating in the study group were carried out before the first exposure to hyperbaric oxygen and then at the end of therapy, after at least 25 sessions of treatment. In the control group, examination of perception of taste sensations was conducted only once. The results of comparing patients with non-healing wounds with healthy people are characterized by reduced taste sensitivity. After participation in hyperbaric oxygen therapy, the improvement in perception of taste sensations and changes in hedonic evaluation have occurred among patients with non-healing wounds. In terms of food preference, a decreased desire for eating sweet desserts, chocolate, and crisps was observed in those patients who received hyperbaric oxygen therapy.