Taste dysfunction: a practical guide for oral medicine

Giving a Voice to Patients With Smell Disorders Associated With COVID-19: Cross-Sectional Longitudinal Analysis Using Natural Language Processing of Self-Reports

BACKGROUND

Smell disorders are commonly reported with COVID-19 infection. The smell-related issues associated with COVID-19 may be prolonged, even after the respiratory symptoms are resolved. These smell dysfunctions can range from anosmia (complete loss of smell) or hyposmia (reduced sense of smell) to parosmia (smells perceived differently) or phantosmia (smells perceived without an odor source being present). Similar to the difficulty that people experience when talking about their smell experiences, patients find it difficult to express or label the symptoms they experience, thereby complicating diagnosis. The complexity of these symptoms can be an additional burden for patients and health care providers and thus needs further investigation.

OBJECTIVE

This study aims to explore the smell disorder concerns of patients and to provide an overview for each specific smell disorder by using the longitudinal survey conducted in 2020 by the Global Consortium for Chemosensory Research, an international research group that has been created ad hoc for studying chemosensory dysfunctions. We aimed to extend the existing knowledge on smell disorders related to COVID-19 by analyzing a large data set of self-reported descriptive comments by using methods from natural language processing.

METHODS

We included self-reported data on the description of changes in smell provided by 1560 participants at 2 timepoints (second survey completed between 23 and 291 days). Text data from participants who still had smell disorders at the second timepoint (long-haulers) were compared with the text data of those who did not (non-long-haulers). Specifically, 3 aims were pursued in this study. The first aim was to classify smell disorders based on the participants' self-reports. The second aim was to classify the sentiment of each self-report by using a machine learning approach, and the third aim was to find particular food and nonfood keywords that were more salient among long-haulers than those among non-long-haulers.

RESULTS

We found that parosmia (odds ratio [OR] 1.78, 95% CI 1.35-2.37; P<.001) as well as hyposmia (OR 1.74, 95% CI 1.34-2.26; P<.001) were more frequently reported in long-haulers than in non-long-haulers. Furthermore, a significant relationship was found between long-hauler status and sentiment of self-report (P<.001). Finally, we found specific keywords that were more typical for long-haulers than those for non-long-haulers, for example, fire, gas, wine, and vinegar.

CONCLUSIONS

Our work shows consistent findings with those of previous studies, which indicate that self-reports, which can easily be extracted online, may offer valuable information to health care and understanding of smell disorders. At the same time, our study on self-reports provides new insights for future studies investigating smell disorders.

Dysgeusia in Patients with Breast Cancer Treated with Chemotherapy-A Narrative Review

Breast cancer (BC) is the most common cancer worldwide. Chemotherapy (CT) is essential for the treatment of BC, but is often accompanied by several side effects, including taste alterations, due to different mechanisms. Although dysgeusia is usually underestimated by clinicians, it is considered very worrying and disturbing by cancer patients undergoing CT, because it induces changes in dietary choices and social habits, affecting their physical and psychological health, with a profound impact on their quality of life. Several strategies and therapies have been proposed to prevent or alleviate CT-induced dysgeusia. This review aimed to evaluate the available evidence on prevalence, pathophysiological mechanisms, clinical consequences, and strategies for managing dysgeusia in BC patients receiving CT. We queried the National Library of Medicine, the Cochrane Library, Excerpta Medica dataBASE, and the Cumulative Index to Nursing and Allied Health Literature database, performing a search strategy using database-specific keywords. We found that the literature on this topic is scarce, methodologically limited, and highly heterogeneous in terms of study design and criteria for patient inclusion, making it difficult to obtain definitive results and make recommendations for clinical practice.

How to Manage Taste Disorders

Purpose of the Review

This study aims to summarize the current state of the art of how taste disorders are clinically best managed.

Recent Findings

Taste disorders are distressing for the concerned patients since eating and drinking become bothersome or impossible. Apart from nutritional problems, quality of life is impaired. Still, diagnosis and treatment of taste disorders are elusive, and general knowledge about taste and its affection is little within the population and the medical community. This review stresses the importance of accurate workup and diagnosis of taste disorders in order to offer an effective treatment. Yet unclear aspects of taste disorders are discussed, and interesting findings regarding the treatment of taste disorders are reviewed. A special focus is given to current pharmacological options on how to treat taste disorders.

Summary

Despite impressive insights into the gustatory function and molecular logic of taste receptor cells, there is currently poor clinical knowledge on the pathophysiology of taste disorders in humans. Diagnosing, measuring, and treating gustatory disorders remain restricted to a handful of specialized smell and taste centers worldwide. Despite interesting work on potential drugs treating taste disorders, many of the reported medications lack controlled and randomized trials confirming their efficacy in taste dysfunction. Future efforts need to be focused on the treatment of taste disorders.

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.

Chemosensory Dysfunction Induced by Environmental Pollutants and Its Potential As a Novel Neurotoxicological Indicator: A Review

Air pollution composed of the complex interactions among particular matter, chemicals, and pathogens is an emerging and global environmental issue that closely correlates with a variety of diseases and adverse health effects, especially increasing incidences of neurodegenerative diseases. However, as one of the prevalent health outcomes of air pollution, chemosensory dysfunction has not attracted enough concern until recently. During the COVID-19 pandemic, multiple scientific studies emphasized the plausibly essential roles of the chemosensory system in the airborne transmission airway of viruses into the human body, which can also be utilized by pollutants. In this Review, in addition to summarizing current progress regarding the contributions of traditional air pollutants to chemosensory dysfunction, we highlight the roles of emerging contaminants. We not only sum up clarified mechanisms, such as inflammation and apoptosis but also discuss some not yet completely identified mechanisms, e.g., disruption of olfactory signal transduction. Although the existing evidence is not overwhelming, the chemosensory system is expected to be a useful indicator in neurotoxicology and neural diseases based on accumulating studies that continually excavate the deep link between chemosensory dysfunction and neurodegenerative diseases. Finally, we argue the importance of studies concerning chemosensory dysfunction in understanding the health effects of air pollution and provide comments for some future directions of relevant research.

Regulation effect of lipopolysaccharide on the alternative splicing and function of sweet taste receptor T1R2

OBJECTIVES

To identify the alternative splicing isoform of mouse sweet taste receptor T1R2, and investigate the effect of lipopolysaccharide (LPS) local injection on T1R2 alternative splicing and the function of sweet taste receptor as one of the bacterial virulence factors.

METHODS

After mouse taste bud tissue isolation was conducted, RNA extraction and reverse transcription polymerase chain reaction (PCR) were performed to identify the splicing isoform of T1R2. Heterologous expression experiments in vitro were utilized to detect how the T1R2 isoform regulated the function of sweet taste receptors. The effect of local LPS injection on the expression of the T1R2 isoform was measured by real-time fluorescent quantitative PCR.

RESULTS

T1R2 splicing isoform T1R2_Δe3p formed sweet taste receptors with T1R3, which could not be activated by sweet taste stimuli and significantly downregulated the function of canonical T1R2/T1R3. Local LPS injection significantly increased the expression ratio of T1R2_Δe3p in mouse taste buds.

CONCLUSIONS

LPS stimulation affects the alternative splicing of mouse sweet taste receptor T1R2 and significantly upregulates the expression of non-functional isoform T1R2_Δe3p, suggesting that T1R2 alternative splicing regulation may be one of the mechanisms by which microbial infection affects host taste perception.

Putting the 2019 Nutrition Recommendations for Pressure Injury Prevention and Treatment into Practice

GENERAL PURPOSE

To explore the changes in the National Pressure Injury Advisory Panel, European Pressure Ulcer Advisory Panel, and Pan Pacific Pressure Injury Alliance Clinical Practice Guideline for Prevention and Treatment of Pressure Ulcers/Injuries (CPG) nutrition recommendations and strategies for implementation.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant will:1. Synthesize the current evidence regarding nutrition approaches to medical conditions, including pressure injury prevention and treatment.2. Summarize the changes and recommendations in the 2019 edition of the CPG.

ABSTRACT

Healthy diets provide essential nutrients needed to maintain healthy skin and prevent or manage pressure injuries. The 2019 Clinical Practice Guideline for Prevention and Treatment of Pressure Ulcers/Injuries published by the National Pressure Injury Advisory Panel, European Pressure Ulcer Advisory Panel, and Pan Pacific Pressure Injury Alliance includes specific nutrition recommendations for patients with pressure injuries. The purpose of this CE/CME article is to explore the changes in the nutrition recommendations and strategies for implementation.

Loss of Olfactory Function-Early Indicator for Covid-19, Other Viral Infections and Neurodegenerative Disorders

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.

Toxic exposures and the senses of taste and smell

This review addresses the adverse influences of neurotoxic exposures on the ability to smell and taste. These chemical senses largely determine the flavor of foods and beverages, impact food intake, and ultimately nutrition, and provide a warning for spoiled or poisonous food, leaking natural gas, smoke, airborne pollutants, and other hazards. Hence, toxicants that damage these senses have a significant impact on everyday function. As noted in detail, a large number of toxicants encountered in urban and industrial air pollution, including smoke, solvents, metals, and particulate matter can alter the ability to smell. Their influence on taste, i.e., sweet, sour, bitter, salty, and savory (umami) sensations, is not well documented. Given the rather direct exposure of olfactory receptors to the outside environment, olfaction is particularly vulnerable to damage from toxicants. Some toxicants, such as nanoparticles, have the potential to damage not only the olfactory receptor cells, but also the central nervous system structures by their entrance into the brain through the olfactory mucosa.

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.

Gustatory dysfunction

Tastes in humans provide a vital tool for screening soluble chemicals for food evaluation, selection, and avoidance of potentially toxic substances. Taste or gustatory dysfunctions are implicated in loss of appetite, unintended weight loss, malnutrition, and reduced quality of life. Dental practitioners are often the first clinicians to be presented with complaints about taste dysfunction. This brief review provides a summary of the common causes of taste disorders, problems associated with assessing taste function in a clinical setting and management options available to the dental practitioner.

Oral toxicity produced by chemotherapy: A systematic review

Introduction: Antineoplastic chemotherapy remains one of the most widely used management strategies in cancer, either alone or in combination with other types of treatment. The main inconvenience of chemotherapy is its lack of selectivity, since it acts upon both tumor cells and rapidly multiplying normal cells such as bone marrow cells, hair follicle cells and oral and gastrointestinal mucosal cells. Material and method: An exhaustive search was made of the main oral toxic effects of chemotherapy in the PubMed-Medline, Cochrane Library and Scopus databases. A total of 1293 articles were identified, of which 333 met the study inclusion criteria. Results: The toxic effects of chemotherapy at oral mucosal level comprise mucositis, osteonecrosis of the jaws secondary to bisphosphonate use, susceptibility to infections, dental alterations, salivary and neurological disorders, dysgeusia and bleeding tendency. These complications have a negative impact upon patient quality of life, and in some cases can prove life-threatening. Conclusions: Evaluation of patient oral and dental health is essential before administering chemotherapy, in order to minimize the risk of oral and systemic complications of such treatment.

Key words:Chemotherapy, oral complications, dental, saliva and osteonecrosis jaw.

Oral complications and management strategies for patients undergoing cancer therapy

With cancer survival rate climbing up over the past three decades, quality of life for cancer patients has become an issue of major concern. Oral health plays an important part in one's overall quality of life. However, oral health status can be severely hampered by side effects of cancer therapies including surgery, chemotherapy, radiotherapy, and hematopoietic stem cell transplantation. Moreover, prevention and treatment of these complications are often overlooked in clinical practice. The present paper aims at drawing health care professionals' attention to oral complications associated with cancer therapy by giving a comprehensive review. Brief comments on contemporary cancer therapies will be given first, followed by detailed description of oral complications associated with cancer therapy. Finally, a summary of preventive strategies and treatment options for common oral complications including oral mucositis, oral infections, xerostomia, and dysgeusia will be given.

An evolutionary perspective on food and human taste

The sense of taste is stimulated when nutrients or other chemical compounds activate specialized receptor cells within the oral cavity. Taste helps us decide what to eat and influences how efficiently we digest these foods. Human taste abilities have been shaped, in large part, by the ecological niches our evolutionary ancestors occupied and by the nutrients they sought. Early hominoids sought nutrition within a closed tropical forest environment, probably eating mostly fruit and leaves, and early hominids left this environment for the savannah and greatly expanded their dietary repertoire. They would have used their sense of taste to identify nutritious food items. The risks of making poor food selections when foraging not only entail wasted energy and metabolic harm from eating foods of low nutrient and energy content, but also the harmful and potentially lethal ingestion of toxins. The learned consequences of ingested foods may subsequently guide our future food choices. The evolved taste abilities of humans are still useful for the one billion humans living with very low food security by helping them identify nutrients. But for those who have easy access to tasty, energy-dense foods our sensitivities for sugary, salty and fatty foods have also helped cause over nutrition-related diseases, such as obesity and diabetes.

Cacogeusia following pine nut ingestion: a six patient case series

This is a retrospective case series of 6 patients complaining of a bad taste (cacogeusia) specifically metallogeusia, following the ingestion of pine nuts.(1) The taste arose always within 48h of ingestion, and in all but one patient spontaneously resolved within 14 days. Pine nuts also have a potential for triggering anaphylaxis.(2).