Time-frequency analysis of gustatory event related potentials (gERP) in taste disorders.

In taste disorders, the key to a correct diagnosis and an adequate treatment is an objective assessment. Compared to psychophysical tests, EEG-derived gustatory event-related potentials (gERP) could be used as a less biased measure. However, the responses identified using conventional time-domain averaging show a low signal-to-noise ratio. This study included 44 patients with dysgeusia and 59 healthy participants, who underwent a comprehensive clinical examination of gustatory function. gERPs were recorded in response to stimulation with two concentrations of salty solutions, which were applied with a high precision gustometer. Group differences were examined using gERP analyzed in the canonical time domain and with Time-Frequency Analyses (TFA). Dysgeusic patients showed significantly lower scores for gustatory chemical and electrical stimuli. gERPs failed to show significant differences in amplitudes or latencies between groups. However, TFA showed that gustatory activations were characterized by a stronger power in controls than in patients in the low frequencies (0.1-4 Hz), and a higher desynchronization in the alpha-band (8-12 Hz). Hence, gERPs reflect the altered taste sensation in patients with dysgeusia. TFA appears to enhance the signal-to-noise ratio commonly present when using conventional time-domain averaging, and might be of assistance for the diagnosis of dysgeusia.

Association of gustatory dysfunction and Alzheimer.

BACKGROUND: Chemosensory dysfunction has been reported to be involved in the pathogenesis of Alzheimer’s disease (AD). Compared with olfaction, gustatory dysfunction in AD has not been evaluated in depth. We reviewed previously published studies regarding gustatory dysfunction in patients with AD compared with healthy controls. METHODS: A systematic review was conducted by searching the MEDLINE, Cochrane Library, Embase, and PubMed databases covering publications from January 2000 to February 2023. The search was performed using the keyword "Alzheimer* AND (gustatory OR taste OR gustation)." Only studies that performed gustatory function testing and compared the results between patients with AD and healthy controls were included. A random-effects meta-analysis was performed. RESULTS: Twelve articles were finally included, and various gustatory tests including taste strips, the taste disk test, taste solutions, and subjective questionnaires were applied. Overall gustatory function based on the taste strip test was significantly decreased in patients with AD compared with controls in two out of three papers. The overall gustatory function of patients with AD was significantly decreased in all studies based on the taste disk and taste solution tests. We also found that the sweet taste test showed low heterogeneity across all the included studies, and there was low publication bias. In studies using subjective questionnaires, gustatory function was not significantly different between patients with AD and healthy controls in the meta-analysis. CONCLUSIONS: Based on these studies, gustatory dysfunction diagnosed by gustatory function testing was closely related to AD. However, the results of subjective questionnaires were not significantly different between patients with AD and healthy controls in the current meta-analysis. As the number of studies and enrolled subjects was limited and unified gustatory function testing was lacking, further studies are needed to confirm this relationship.

The relationship between loneliness, psychological resilience, quality of life and taste change in cancer patients receiving chemotherapy.

PURPOSE: This study aimed to determine the correlation between taste change, nutritional intake and quality of life in cancer patients receiving chemotherapy. A total of 610 (F = 314, M = 296) volunteers aged 19 and 65 who received outpatient chemotherapy treatment participated in the study. METHODS: Individuals' general information was obtained, anthropometric measurements were carried out, malnutrition status (Patient-Generated Subjective Global Assessment PG-SGA), loneliness (Cancer Loneliness Scale), psychological resilience (Psychological Resilience Scale), quality of life (Quality of Life Scale (EORT QLQ-C30) and taste changes were scrutinized [Chemotherapy-Induced Taste Alteration Scale (CiTAS)]. RESULTS: There was a negative correlation between the Cancer Loneliness Scale and PG-SGA and General Health Status (r = -0.494, p = 0.000; r = -0.406, p = 0.000) and a positive correlation with Symptom Scales (r = 0.484, p = 0.000; r = 0.506, p = 0.000) (p < 0.05). There was a positive correlation between the Psychological Resilience Scale and General Health Status (r = 0.393, P = 0.000), Functional Scales (r = 0.349, P = 0.000), and a negative correlation between Symptom Scales (r = -0.302, p = 0.000) (p < 0.05). 70.9% of men and 70.7% of women had severe malnutrition. General Taste Changes, General Health and Symptom Scale values were significant predictors of severe malnutrition status (p < 0.05). CONCLUSION: The symptoms that develop during the treatment process cause many psychological problems. Before starting treatment, patients should be evaluated comprehensively, depression anxiety levels and quality of life levels should be determined, and precautions should be taken accordingly.

Oral manifestations of COVID-19 in unvaccinated patients: a cross-sectional study.

BACKGROUND: Early studies have highlighted the possible development of dysgeusia and anosmia in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and these manifestations should be considered a potential indication of coronavirus disease 19 (COVID-19). As potential contributors to these symptoms, dentists should perform careful oral and oropharyngeal examinations and document suspicious oral lesions in patients with COVID-19, especially in those who complain of loss of taste and smell. The study's objective was to assess the prevalence of oral manifestations among ambulatory unvaccinated symptomatic patients with suspected COVID-19 during the acute phase of the disease. METHODS: This cross-sectional study evaluated oral manifestations in adults (aged ≥ 18 years) with suspected and confirmed SARS-CoV-2 infection. Chi-square and Fisher's exact tests were used to compare data between the groups (rRT-PCR-positive and rRT-PCR-negative patients). RESULTS: One hundred thirty-six participants were included. Most were female (n = 79; 58.1%), with a mean age of 39.53 (± 14.17) years. Of these, 54 (39.7%) had a positive rRT-PCR test, and 82 (60.3%) had negative rRT-PCR results. Oral manifestations were observed in 40 participants (74.1%) in the rRT-PCR-positive group and 67 participants (81.7%) in the rRT-PCR-negative group. The most common oral manifestations were xerostomia (n = 85; 62.5%) and dysgeusia/ageusia (n = 57; 41.9%). Different rates of gingivitis (n = 12; 22.2% vs. n = 5; 6.1%; p = 0.005) and halitosis (n = 7; 13.0% vs. n = 1; 1.2%; p = 0.007) were observed between the rRT-PCR-positive and -negative groups, respectively. Mouth ulcers, glossitis, tongue coating, and petechiae were reported in both groups without significant differences. CONCLUSIONS: A high prevalence of oral manifestations was observed in symptomatic patients with suspected or confirmed COVID-19. CLINICAL RELEVANCE: This study highlights the importance of routine oral examinations by dentists as part of the multidisciplinary care of COVID-19 patients.

Lithium-Induced Dysgeusia and Hyposmia: A Case Report and a Literature Review.

BACKGROUND: Bipolar disorder is a complex psychiatric disorder where long-term treatment is crucial to maintain stabilization. Although largely well tolerated, lithium has a wide spectrum of adverse effects in different organs and seems to also cause taste and smell disorders, which remain rare and not largely described. We aim to present a rare case of hyposmia and dysgeusia secondary to lithium treatment in a bipolar patient and also conduct a review on these rare lithium adverse effects. CASE PRESENTATION: The case is a 43-year-old woman with type I bipolar disorder who became stabilized and fully functional with lithium therapy. After 4 months of treatment, she began to notice progressive hyposmia and dysgeusia. After multiple diagnostic and screening tests, lithium was implicated as the cause of the symptoms, which led to a switch to valproic acid. After 3 months, she was not compensated with valproic acid treatment, returned to lithium therapy despite its adverse effects, and became stabilized again. CONCLUSIONS: There are few data on lithium therapy taste and smell adverse effects. Most studies on this topic are likely to be case reports. Lithium therapy may cause dysgeusia and hyposmia, although mechanisms are not fully understood. These adverse effects can interfere negatively in patient's treatment adherence. Therefore, physicians who prescribe lithium should be aware of them. Further structured studies are needed to better understand these lithium rare adverse effects and the appropriate way to assess and monitoring them.

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

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

Comparative Study of Chemosensory Dysfunction in COVID-19 in 2 Geographically Distinct Regions.

OBJECTIVE: To directly compare the prevalence of chemosensory dysfunction (smell and taste) in geographically distinct regions with the same questionnaires. METHODS: A cross-sectional study was performed to evaluate the self-reported symptoms among adults (older than 18 years) who underwent COVID-19 testing at an ambulatory assessment center in Canada and at a hospital in Israel between March 16, 2020, and August 19, 2020. The primary outcome was the prevalence of self-reported chemosensory dysfunction (anosmia/hypomsia and dysgeusia/ageusia). Subgroup analysis was performed to evaluate the prevalence of chemosensory deficits among the outpatients. RESULTS: We identified a total of 350 COVID-19-positive patients (138 Canadians and 212 Israelis). The overall prevalence of chemosensory dysfunction was 47.1%. There was a higher proportion of chemosensory deficits among Canadians compared to Israelis (66.7% vs 34.4%, P < .01). A subgroup analysis for outpatients (never hospitalized) still identified a higher prevalence of chemosensory dysfunction among Canadians compared to Israelis (68.2% vs 36.1%, P < 0.01). A majority of patients recovered their sense of smell after 4 weeks of symptom onset. CONCLUSION: Although the prevalence of chemosensory deficit in COVID-19 was found to be similar to previously published reports, the prevalence can vary significantly across different geographical regions. Therefore, it is important to obtain regionally specific data so that the symptom of anosmia/dysgeusia can be used as a guide for screening for the clinical diagnosis of COVID-19.

[Gustatory disorders in COVID-19]. / Narusheniya vkusooshchushcheniya pri COVID-19.

Taste disturbances are present in 20.3-88.0% of COVID-19 cases and are the first signs of infection in 11.0-18.1% of cases. They often manifested 3-7 days after the onset of general respiratory symptoms and last 2 to 16 days, followed by recovery. There are also prolonged disturbances of taste sensation (up to 61-76 days or more), which is associated with damage to various types of receptor cells of the mucous membrane of the tongue. More severe taste disturbances are recorded in the elderly. In women, changes in taste sensation are noted more often than in men, and with a longer recovery period. Severe and critical forms of taste disorders predominate in COVID-19; dysgeusia, as a rule, prevails over hypogeusia and ageusia. Taste disturbance is a common clinical symptom in COVID-19, which can and should be considered as a marker of early manifestation of coronavirus infection.

Factors associated with development and persistence of post-COVID conditions: A cross-sectional study.

INTRODUCTION: The post-COVID condition has become a social concern. Although the patient characteristics associated with the development of this condition are partially known, those associated with its persistence have not been identified. METHODS: We conducted a cross-sectional questionnaire-based survey among patients who had recovered from COVID-19 and visited the National Center for Global Health and Medicine between February 2021 and March 2021. Demographic and clinical data, and data regarding the presence and duration of post-COVID conditions were obtained. We identified factors associated with the development and persistence of post-COVID conditions using multivariate logistic and linear regression analyses, respectively. RESULTS: We analyzed 457 of 526 responses (response rate, 86.9%). The median patient age was 47 years. Of these, 378 patients (84.4%) had mild disease in the acute phase. The number of patients with symptoms at 6 and 12 months after onset or diagnosis was 120 (26.3%) and 40 (8.8%), respectively. Women were at risk of developing fatigue (odds ratio [OR]: 2.03, 95% confidence interval [CI]: 1.31-3.14), dysosmia (OR: 1.91, 95%CI: 1.24-2.93), dysgeusia (OR: 1.56, 95%CI: 1.02-2.39), hair loss (OR: 3.00, 95%CI: 1.77-5.09), and persistence of any symptoms (coefficient: 38.0, 95%CI: 13.3-62.8). Younger age and low body mass index were factors for developing dysosmia (OR: 0.96, 95%CI: 0.94-0.98 and OR: 0.94, 95%CI: 0.89-0.99, respectively) and dysgeusia (OR: 0.98, 95%CI: 0.96-1.00 and OR: 0.93, 95%CI: 0.88-0.98, respectively). CONCLUSION: We identified factors involved in the development and persistence of post-COVID conditions. Many patients, even those with mild conditions, experience long-term residual symptoms.

[A case of left dysgeusia due to hemorrhage near the left superior cerebellar peduncle].

We report a rare case with unilateral dysgeusia due to cerebrovascular disease. A 45-year-old man was admitted to the hospital with a sudden onset of dysesthesia in the right face and upper and lower limbs. A CT scan revealed a left pontine hemorrhage. A day after onset, the patient became aware of unilateral dysgeusia. Electrogustometry showed significantly higher thresholds in the left chorda tympani nerve and glossopharyngeal nerve compared to the right nerves. We diagnosed the hemorrhage caused unilateral dysgeusia. Although dysesthesia in the right face and upper and lower limbs disappeared, the dysgeusia in the left tongue persisted six months after symptom onset. Based on the neurological and radiological findings in this case, we discuss the central gustatory pathway with literatures.

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.

The etiologies and considerations of dysgeusia: A review of literature.

BACKGROUND: Dysgeusia is a prevalent qualitative gustatory impairment that may affect food intake and quality of life. The facial (VII), glossopharyngeal (IX), and vagus (X) nerves are the three cranial nerves responsible for sensing taste. Typically, dysgeusia is considered a general term for all taste disorders. In addition, dysgeusia may be a symptom of underlying systemic conditions such as diabetes mellitus, chronic kidney disease, respiratory infections, and nutritional deficiencies. Various subjective and objective diagnostic approaches are available to aid clinicians, each with its own set of benefits and drawbacks. HIGHLIGHTS: Taste impairment can lead to a lack of enjoyment while eating, food aversion, and malnutrition, resulting in a decrease in the quality of life and loss of muscle mass. Therefore, the present review aims to address the probable etiologies, diagnostic aids, and management of dysgeusia. A broad search for studies was conducted using PubMed, Web of Science, Scopus, and Google Scholar. In addition, relevant studies found in the references of the selected articles were also studied. CONCLUSION: Oral health care providers should be aware of the possible etiologies of dysgeusia, diagnostic tools, and treatment options. Accurate diagnosis of the cause of taste dysfunction has a significant impact on the management of taste impairment.

Temporomandibular Disorders and Oral Features in Idiopathic Inflammatory Myopathies (IIMs) Patients: An Observational Study.

Aim: Inflammatory idiopathic myopathies (IIMs) are inflammatory processes affecting skeletal musculature and extramuscular organs. Temporomandibular disorders (TMD) involve jaw muscles and temporomandibular joint. The aim of this observational study was to investigate the prevalence of the main TMD symptoms and signs as well as oral implications in IIM patients. Methods: The study group included 54 patients (42 women and 12 men), 22 of whom affected by dermatomyositis (DM), 29 by polymyositis (PM) and 3 by inclusion body myositis (IBM). A group of 54 patients not affected by this disease, served as CG. Oral and TMD signs and symptoms were evaluated by means of a questionnaire and through clinical examination. Results: About oral symptoms, the study group complained more frequently dysgeusia, with loss of taste or unpleasant taste (p<0.0001) and feeling of burning mouth (9.4% versus 0 controls). Xerostomia was more prevalent in the study group respect to the CG (p<0.0001). Dysphagia was reported by 48.1% of IIM patients while was absent in CG (p<0.0001). About oral signs, cheilitis (p<0.05) and oral ulcers (p<0.05) were significantly more frequent in CG. As regard to TMD symptoms, arthralgia and tinnitus didn't showed significant differences between the two groups, while neck/shoulders and masticatory muscle pain was significantly more referred in IIM patients than in the CG (p<0.05). About TMJ signs, sounds were overlapping in the two groups: click=11.1% in both IIM patients and CG (p>0.05), crepitation in 11.1% of IIM and 9.3% of controls (p>0.05). No significant difference was detected about deflection (9.3%, p>0.05), while deviation was wider in CG (p<0.05). Active opening and lateralities showed no significant differences, while endfeel was significantly increased in IIM group for a higher presence of muscular contracture. Bruxism was present only in CG. Conclusion: The data collected from this observational study seem to support the existence of a relationship between the prevalence of TMD symptoms and signs as well as oral features in patients with myositis. A remarkable reduction of salivary flow and dysphagia were more frequent and severe in IIM patients, as well as muscle contracture and myofacial pain evoked by palpation, this result being highly significant.

Longitudinal comparisons of a whole-mouth taste test to clinician-rated and patient-reported outcomes of dysgeusia postradiotherapy in patients with head and neck cancer and associations with oral intake.

BACKGROUND: After head and neck cancer (HNC) treatment, dysgeusia may be a barrier to oral intake. In this exploratory study, we prospectively examined taste perception, clinician-rated (CRO) and patient-reported (PRO) taste changes and their effect on oral intake postradiotherapy. METHODS: Twenty-eight patients were assessed at baseline, treatment weeks 2 and 4, and 1, 3, and 6 months post-treatment using a whole-mouth taste test and associated CRO and subjective PRO measures. RESULTS: Greater taste impairment was reflected by subjective than by a whole-mouth taste test. The most significant and consistent decline occurred mid-treatment. The Chemotherapy-Induced Taste Alteration Scale (PRO) discomfort subscale correlated significantly with maintaining an oral diet, percent of oral intake, and appetite level from mid-treatment to 6 months post-treatment. CONCLUSIONS: PRO results indicated ongoing oral intake issues. Whole-mouth taste tests may fail to fully reflect functional taste-loss. Dysgeusia prevention and treatment methods are needed to improve patient outcomes.

Pathogenesis of dysgeusia in COVID-19 patients: a scoping review.

OBJECTIVE: The novel coronavirus disease-19 (COVID-19) pandemic had intense social and economic effects. Patients infected with COVID-19 may present with a series of conditions. A considerable number of patients express taste and smell disturbances as a prodromal, coexistent, or as the only manifestation of COVID-19 infection. The objective of the present review is to review the hypothetical mechanisms of action and etiopathogenesis of dysgeusia in COVID-19 patients. MATERIALS AND METHODS: Multiple scientific databases were explored, including PubMed, Medline, Scopus, Cochrane-library, LILACS, Livivo and OpenGrey. All types of articles that discussed the pathogenesis of dysgeusia were included, while articles that described dysgeusia without detail about its mode of action were excluded. RESULTS: A total of 47 articles, with different designs, were included in this review. These articles suggested direct viral neural invasion to olfactory and gustatory nerves, viral cytotoxicity to taste buds, angiotensin II imbalance, augmented pro-inflammatory cytokines, and disturbances in salivary glands and sialic acid. COVID-19 induced-dysgeusia was also associated with systemic diseases, medications, zinc, chemicals, and disinfectants. CONCLUSIONS: The most likely cause of transient dysgeusia in COVID-19 is peripheral neurotropism and direct toxicity to taste buds or olfactory epithelium. Other factors may also play a contributory role in dysgeusia, such as a defect in the quality and quantity of saliva, pro-inflammatory cytokines, angiotensin II accumulation, systemic diseases, hypozincemia, and excessive use of chemicals.

A comparative study on the clinical features of COVID-19 with non-SARS-CoV-2 respiratory viral infections.

During this coronavirus disease 2019 (COVID-19) pandemic, physicians have the important task of risk stratifying patients who present with acute respiratory illnesses. Clinical presentation of COVID-19, however, can be difficult to distinguish from other respiratory viral infections. Thus, identifying clinical features that are strongly associated with COVID-19 in comparison to other respiratory viruses can aid risk stratification and testing prioritization especially in situations where resources for virological testing and resources for isolation facilities are limited. In our retrospective cohort study comparing the clinical presentation of COVID-19 and other respiratory viral infections, we found that anosmia and dysgeusia were symptoms independently associated with COVID-19 and can be important differentiating symptoms in patients presenting with acute respiratory illness. On the other hand, laboratory abnormalities and radiological findings were not statistically different between the two groups. In comparing outcomes, patients with COVID-19 were more likely to need high dependency or intensive care unit care and had a longer median length of stay. With our findings, we emphasize that epidemiological risk factors and clinical symptoms are more useful than laboratory and radiological abnormalities in differentiating COVID-19 from other respiratory viral infections.

Acute Corneal Endothelial Graft Rejection With Coinciding COVID-19 Infection.

PURPOSE: To report a case of acute corneal endothelial graft rejection with the concurrent onset of coronavirus disease 2019 (COVID-19) symptoms. METHODS: Case report. RESULTS: A 31-year-old African American woman with a history of asthma, sleep apnea, obesity (body mass index of 40), and bilateral keratoconus was noted to have acute corneal endothelial graft rejection 3 months after uncomplicated penetrating keratoplasty of the left eye. The patient developed dysgeusia and subjective fever on the same day as ocular discomfort, and she was subsequently diagnosed with COVID-19 with only these 2 classic symptoms of the viral infection. CONCLUSIONS: Severe acute respiratory syndrome coronavirus 2 is known to cause conjunctivitis and has demonstrated transmissibility through ocular secretions. Acute immune and inflammatory dysregulations have been seen in cases of COVID-19 through various mechanisms. COVID-19 infection may potentially compromise ocular immune privilege contributing to acute corneal graft rejection.

Dysosmia and dysgeusia in patients with COVID-19 in northern Taiwan.

BACKGROUND/PURPOSE: To investigate the characteristics of dysosmia and dysgeusia among patients diagnosed with coronavirus disease 2019 (COVID-19) in Taiwan. METHODS: Prospective data collection between January 22, 2020 to May 7, 2020 of nucleic acid confirmed COVID-19 hospitalized patients in northern Taiwan by the Taiwan Centers for Disease Control were analyzed. RESULTS: Of 217 patients enrolled, 78 (35.9%) reported dysosmia (n = 73, 33.6%) and/or dysgeusia (n = 62, 28.6%). The median duration of COVID-19 associated symptom-onset to development of dysosmia and/or dysgeusia was <1 days (interquartile range [IQR], <1-6 days) and 53 of 78 (67.9%) patients developed dysosmia and/or dysgeusia as one of the initial symptoms of COVID-19. Of 59 closely monitored patients, 41 (69.5%) patients recovered within 3 weeks after symptoms onset and the median time to recovery was 12 days (IQR, 7-20 days). Only 6 of the 59 (10.2%) patients reported persistent dysosmia and/or dysgeusia before discharge from hospitals. Multivariate analysis showed that younger individuals (adjusted hazard ratio [AHR], 0.93 per one-year increase; 95% confidence interval [95% CI], 0.89-0.97; P = 0.001), women (AHR, 2.76; 95% CI, 1.05-7.25; P = 0.04) and travel to North America (AHR, 2.35; 95% CI, 1.05-5.26; P = 0.04) were the significant factors associated with dysosmia and/or dysgeusia. CONCLUSION: Dysosmia and/or dysgeusia are common symptoms and clues for the diagnosis of COVID-19, particularly in the early stage of the disease. Physicians should be alerted to these symptoms to make timely diagnosis and management for COVID-19 to limit spread.