Cyclophosphamide induces the loss of taste bud innervation in mice.

Many common chemotherapeutics produce disruptions in the sense of taste which can lead to loss of appetite, nutritional imbalance, and reduced quality of life, especially if taste loss persists after treatment ends. Cyclophosphamide (CYP), an alkylating chemotherapeutic agent, affects taste sensitivity through its cytotoxic effects on mature taste receptor cells (TRCs) and on taste progenitor cell populations, retarding the capacity to replace TRCs. Mechanistic studies have focused primarily on taste cells, however, taste signaling requires communication between TRCs and the gustatory nerve fibers that innervate them. Here, we evaluate cyclophosphamide's effects on the peripheral gustatory nerve fibers that innervate the taste buds. Following histological analysis of tongue tissues, we find that CYP reduces innervation within the fungiform and circumvallates taste buds within 4 days after administration. To better understand the dynamics of the denervation process, we used 2-photon intravital imaging to visualize the peripheral gustatory nerve fibers within individual fungiform taste buds up to 20 days after CYP treatment. We find that gustatory fibers retract from the taste bud properly but are maintained within the central papilla core. These data indicate that in addition to TRCs, gustatory nerve fibers are also affected by CYP treatment. Because the connectivity between TRCs and gustatory neurons must be re-established for proper function, gustatory fibers should continue to be included in future studies to understand the mechanisms leading to chemotherapy-induced persistent taste loss.

The burden of persistent symptoms after COVID-19 (long COVID): a meta-analysis of controlled studies in children and adults.

BACKGROUND: Previous meta-analyses estimating the prevalence of the post-COVID-19 condition (PCC) were confounded by the lack of negative control groups. This may result in an overestimation of the prevalence of those experiencing PCC, as these symptoms are non-specific and common in the general population. In this study, we aimed to compare the burden of persistent symptoms among COVID-19 survivors relative to COVID-19-negative controls. METHODS: A systematic literature search was conducted using the following databases (PubMed, Web of Science, and Scopus) until July 2023 for comparative studies that examined the prevalence of persistent symptoms in COVID-19 survivors. Given that many of the symptoms among COVID-19 survivors overlap with post-hospitalization syndrome and post-intensive care syndrome, we included studies that compare the prevalence of persistent symptoms in hospitalized COVID-19 patients relative to non-COVID-19 hospitalized patients and in non-hospitalized COVID-19 patients relative to healthy controls that reported outcomes after at least 3 months since infection. The results of the meta-analysis were reported as odds ratios with a 95% confidence interval based on the random effects model. RESULTS: Twenty articles were included in this study. Our analysis of symptomatology in non-hospitalized COVID-19 patients compared to negative controls revealed that the majority of symptoms examined were not related to COVID-19 infection and appeared equally prevalent in both cohorts. However, non-COVID-19 hospitalized patients had higher odds of occurrence of certain symptoms like anosmia, ageusia, fatigue, dyspnea, and brain fog (P < 0.05). Particularly, anosmia and ageusia showed substantially elevated odds relative to the negative control group at 11.27 and 9.76, respectively, P < 0.05. In contrast, analysis of hospitalized COVID-19 patients compared to those hospitalized for other indications did not demonstrate significantly higher odds for the tested symptoms. CONCLUSIONS: The persistent symptoms in COVID-19 survivors may result from hospitalization for causes unrelated to COVID-19 and are commonly reported among the general population. Although certain symptoms exhibited higher odds in non-hospitalized COVID-19 patients relative to controls, these symptoms are common post-viral illnesses. Therefore, the persistent symptoms after COVID-19 may not be unique to SARS-CoV-2. Future studies including well-matched control groups when investigating persistent symptoms in COVID-19 survivors are warranted to draw a firm conclusion.

Long-term symptoms after SARS-CoV-2 infection in a cohort of hospital employees: duration and predictive factors.

PURPOSE: To evaluate the frequency, duration and patterns of long-term coronavirus disease 2019 (COVID-19) symptoms and to analyse risk factors for long-lasting COVID-19 sequelae among a cohort of hospital employees (HEs). METHODS: We conducted a survey regarding persistent COVID-19 related symptoms with all HEs from three medical centres in Cologne, Germany, who were tested SARS-CoV-2 PCR positive from March 2020 until May 2021. Duration of symptoms and possible risk factors for protracted COVID-19 course were analysed. RESULTS: Of 221 included HEs, a number of 104 HEs (47.1%) reported at least one persisting symptom for more than 90 days after initial SARS-CoV-2 detection. Each one cycle higher initial Ct value significantly increased the chances of overcoming symptoms (odds ratio [OR] 1.05; 95% confidence interval (95%CI) 1.01-1.09; p = 0.019). The occurrence of breathlessness within the first ten days (OR 7.89; 95%CI 1.87-41.43; p = 0.008), an initial Ct value under 30 (OR 3.36; 95%CI 1.22-9.94; p = 0.022) as well as the occurrence of anosmia or ageusia within the first ten days (OR 3.01; 95%CI 1.10-8.84; p = 0.037) showed a statistically significant association with increased odds of illness duration over 90 days. CONCLUSION: About half of the HEs suffered from long lasting symptoms over 90 days after almost entirely mild acute COVID-19. Predictive factors could possibly be used for early treatment to prevent development of long-term symptoms after COVID-19 in future.

The predictive role of symptoms in COVID-19 diagnostic models: A longitudinal insight.

To investigate the symptoms of SARS-CoV-2 infection, their dynamics and their discriminatory power for the disease using longitudinally, prospectively collected information reported at the time of their occurrence. We have analysed data from a large phase 3 clinical UK COVID-19 vaccine trial. The alpha variant was the predominant strain. Participants were assessed for SARS-CoV-2 infection via nasal/throat PCR at recruitment, vaccination appointments, and when symptomatic. Statistical techniques were implemented to infer estimates representative of the UK population, accounting for multiple symptomatic episodes associated with one individual. An optimal diagnostic model for SARS-CoV-2 infection was derived. The 4-month prevalence of SARS-CoV-2 was 2.1%; increasing to 19.4% (16.0%-22.7%) in participants reporting loss of appetite and 31.9% (27.1%-36.8%) in those with anosmia/ageusia. The model identified anosmia and/or ageusia, fever, congestion, and cough to be significantly associated with SARS-CoV-2 infection. Symptoms' dynamics were vastly different in the two groups; after a slow start peaking later and lasting longer in PCR+ participants, whilst exhibiting a consistent decline in PCR- participants, with, on average, fewer than 3 days of symptoms reported. Anosmia/ageusia peaked late in confirmed SARS-CoV-2 infection (day 12), indicating a low discrimination power for early disease diagnosis.

Bilateral hypogeusia and food aversion due to lacunar infarct in the right dorsomedial pontine tegmentum.

A 70-year-old right-handed housewife suffered an acute loss of taste, an unpleasant change in the taste of foods and liquids, and a strong aversion to all kinds of food due to a small lacune in the right dorsomedial pontine tegmentum. Eating became so unpleasant that she lost 7 kg in three weeks. Olfaction and the sensibility of the tongue were spared. The right medial longitudinal fascicle, the central tegmental tract, or both, were injured by the tegmental lesion. A discrete right-sided lesion in the upper pontine tegmentum may cause a reversible syndrome consisting of bilateral hypogeusia which is more severe ipsilaterally.

Loss of sweet taste despite the conservation of sweet receptor genes in insectivorous bats.

The evolution of taste perception is usually associated with the ecology and dietary changes of organisms. However, the association between feeding ecology and taste receptor evolution is unclear in some lineages of vertebrate animals. One example is the sweet taste receptor gene Tas1r2 Previous analysis of partial sequences has revealed that Tas1r2 has undergone equally strong purifying selection between insectivorous and frugivorous bats. To test whether the sweet taste function is also important in bats with contrasting diets, we examined the complete coding sequences of both sweet taste receptor genes (Tas1r2 and Tas1r3) in 34 representative bat species. Although these two genes are highly conserved between frugivorous and insectivorous bats at the sequence level, our behavioral experiments revealed that an insectivorous bat (Myotis ricketti) showed no preference for natural sugars, whereas the frugivorous species (Rousettus leschenaultii) showed strong preferences for sucrose and fructose. Furthermore, while both sweet taste receptor genes are expressed in the taste tissue of insectivorous and frugivorous bats, our cell-based assays revealed striking functional divergence: the sweet taste receptors of frugivorous bats are able to respond to natural sugars whereas those of insectivorous bats are not, which is consistent with the behavioral preference tests, suggesting that functional evolution of sweet taste receptors is closely related to diet. This comprehensive study suggests that using sequence conservation alone could be misleading in inferring protein and physiological function and highlights the power of combining behavioral experiments, expression analysis, and functional assays in molecular evolutionary studies.

COVID-19 associated anosmia in pediatric patients: subject publications review.

OBJECTIVE: Aim: To review the publications subject to the problem of COVID-19 associated anosmia incidence in pediatric patients as well as its pathogenesis, diagnostics, treatment and recovery. The peculiarity of pediatric COVID-19 anosmia is due to children accounting for very low percentage of COVID-19 patients (comparing to one in adults), mostly with milder course of the disease. Awareness of anosmia and its proper diagnostics is crucial in children and adolescents, considering it can be the only manifestation in COVID-19 positive pediatric patients. PATIENTS AND METHODS: Materials and Methods: In order to achieve this goal a meta-analysis of information from databases followed by statistical processing and generalisation of the obtained data was carried out. CONCLUSION: Conclusions: Publications on COVID-19 anosmia in children and adolescents are less numerous than those concerning adult patients, so it is important to use every single trustworthy one. Anosmia/ageusia may be the only symptom, early identifier and the strongest predictor of COVID-19 infection in pediatric patients. Prospects for further scientific researches. Further researches regarding differential diagnostics of COVID-19 and other infections, including seasonal influenza, manifesting with both olfactory and taste dysfunction as well as anosmia diagnostics in children and adolescents with autistic spectrum and different types of mental disorders are possible.

SARS-CoV-2 infection in children evaluated in an ambulatory setting during Delta and Omicron time periods.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and re-emergence of other respiratory viruses highlight the need to understand the presentation of and factors associated with SARS-CoV-2 in pediatric populations over time. The objective of this study was to evaluate the sociodemographic characteristics, symptoms, and epidemiological risk factors associated with ambulatory SARS-CoV-2 infection in children and determine if factors differ by variant type. We conducted a retrospective cohort study of outpatient children undergoing SARS-CoV-2 polymerase chain reaction testing between November 2020 and January 2022. Test-positive were compared with test-negative children to evaluate symptoms, exposure risk, demographics, and comparisons between Omicron, Delta, and pre-Delta time periods. Among 2264 encounters, 361 (15.9%) were positive for SARS-CoV-2. The cohort was predominantly Hispanic (51%), 5-11 years (44%), and 53% male; 5% had received two coronavirus disease 2019 (COVID-19) vaccine doses. Factors associated with a positive test include loss of taste/smell (adjusted odds ratio [aOR]: 6.71, [95% confidence interval, CI: 2.99-15.08]), new cough (aOR: 2.38, [95% CI: 1.69-3.36]), headache (aOR: 1.90, [95% CI: 1.28-2.81), fever (aOR: 1.83, [95% CI: 1.29-2.60]), contact with a positive case (aOR: 5.12, [95% CI: 3.75-6.97]), or household contact (aOR: 2.66, [95% CI: 1.96-3.62]). Among positive children, loss of taste/smell was more predominant during the Delta versus Omicron and pre-Delta periods (12% vs. 2% and 3%, respectively, p = 0.0017), cough predominated during Delta/Omicron periods more than the pre-Delta period (69% and 65% vs. 41%, p = 0.0002), and there were more asymptomatic children in the pre-Delta period (30% vs. 18% and 10%, p = 0.0023). These findings demonstrate that the presentation of COVID-19 in children and most susceptible age groups has changed over time.

Coronavirus infection in chemosensory cells.

Clinical manifestations of human coronavirus (HCoV)-related diseases are mostly related to the respiratory system, although secondary complications such as headache, anosmia, ageusia, and myalgia have been reported. HCoV infection and replication in chemosensory cells associated with ageusia and anosmia is poorly understood. Here, we characterized HCoV-OC43 and SARS-CoV-2 infection in two types of chemosensory cells, olfactory and taste cells, with their unique molecular and histological characteristics. We first assessed HCoV-OC43 infection in in vitro cultured human olfactory epithelial cells (hOECs) and fungiform taste papilla (HBO) cells. Interestingly, while both cell types were susceptible to HCoV-OC43 infection, viral replication rates were significantly reduced in HBO cells compared to hOECs. More interestingly, while culture media from hOECs was able to produce secondary infection in Vero cells, there was very limited secondary infection from HBO cells, suggesting that HBO cells may not be able to release infectious virus. On the other hand, unlike HCoV-OC43, SARS-CoV-2 showed comparable levels of viral infection rates in both hOECs and HBO cells. Furthermore, our RT-qPCR-based gene array studies revealed that several key genes involved in taste and olfactory functions were significantly altered by SARS-CoV-2 infection. These results may suggest a possible mechanism associated with chemosensory symptoms, such as anosmia and ageusia in patients infected with SARS-CoV-2.

Taste loss as a distinct symptom of COVID-19: a systematic review and meta-analysis.

Chemosensory scientists have been skeptical that reports of COVID-19 taste loss are genuine, in part because before COVID-19 taste loss was rare and often confused with smell loss. Therefore, to establish the predicted prevalence rate of taste loss in COVID-19 patients, we conducted a systematic review and meta-analysis of 376 papers published in 2020-2021, with 235 meeting all inclusion criteria. Drawing on previous studies and guided by early meta-analyses, we explored how methodological differences (direct vs. self-report measures) may affect these estimates. We hypothesized that direct measures of taste are at least as sensitive as those obtained by self-report and that the preponderance of evidence confirms taste loss is a symptom of COVID-19. The meta-analysis showed that, among 138,015 COVID-19-positive patients, 36.62% reported taste dysfunction (95% confidence interval: 33.02%-40.39%), and the prevalence estimates were slightly but not significantly higher from studies using direct (n = 15) versus self-report (n = 220) methodologies (Q = 1.73, df = 1, P = 0.1889). Generally, males reported lower rates of taste loss than did females, and taste loss was highest among middle-aged adults. Thus, taste loss is likely a bona fide symptom of COVID-19, meriting further research into the most appropriate direct methods to measure it and its underlying mechanisms.

Covid-19 affects taste independent of taste-smell confusions: results from a combined chemosensory home test and online survey from a large global cohort.

People often confuse smell loss with taste loss, so it is unclear how much gustatory function is reduced in patients self-reporting taste loss. Our pre-registered cross-sectional study design included an online survey in 12 languages with instructions for self-administering chemosensory tests with 10 household items. Between June 2020 and March 2021, 10,953 individuals participated. Of these, 5,225 self-reported a respiratory illness and were grouped based on their reported COVID test results: COVID-positive (COVID+, N = 3,356), COVID-negative (COVID-, N = 602), and COVID unknown for those waiting for a test result (COVID?, N = 1,267). The participants who reported no respiratory illness were grouped by symptoms: sudden smell/taste changes (STC, N = 4,445), other symptoms excluding smell or taste changes (OthS, N = 832), and no symptoms (NoS, N = 416). Taste, smell, and oral irritation intensities and self-assessed abilities were rated on visual analog scales. Compared to the NoS group, COVID+ was associated with a 21% reduction in taste (95% confidence interval (CI): 15-28%), 47% in smell (95% CI: 37-56%), and 17% in oral irritation (95% CI: 10-25%) intensity. There were medium to strong correlations between perceived intensities and self-reported abilities (r = 0.84 for smell, r = 0.68 for taste, and r = 0.37 for oral irritation). Our study demonstrates that COVID-19-positive individuals report taste dysfunction when self-tested with stimuli that have little to none olfactory components. Assessing the smell and taste intensity of household items is a promising, cost-effective screening tool that complements self-reports and may help to disentangle taste loss from smell loss. However, it does not replace standardized validated psychophysical tests.

Safety and efficacy of P2X3 receptor antagonist for the treatment of refractory or unexplained chronic cough: A systematic review and meta-analysis of 11 randomized controlled trials.

BACKGROUND AND OBJECTIVES: Chronic refractory cough is a challenging condition that requires a thorough evaluation and management approach. P2X3 receptors that are ATP-dependent play an important part in nerve fiber sensitization and pathological pain pathways. We conducted this systematic review and meta-analysis to determine the long-term safety and efficacy of P2X3 receptor antagonist drugs in chronic cough. METHODS: We systematically searched PubMed, Scopus, Web of Science, and Embase to identify all relevant published studies through January 15, 2023 that assessed P2X3 antagonists in chronic cough. The protocol was registered in the PROSPERO database with ID: CRD42023422408. Efficacy outcomes were awake (daytime) cough frequency, night cough frequency, 24-h cough frequency, Cough Severity Diary, and total Leicester Cough Questionnaire score. We used the random-effect model to pool the data using RStudio and CMA software. RESULTS: A total of 11 randomized controlled trials comprising 1350 patients receiving a p2x3 antagonist compared to the placebo group were included in this meta-analysis. A significant decrease in 24-h cough frequency (MD = -4.99, 95% CI [-7.15 to -2.82], P < 0.01), awake (daytime) cough frequency (MD = -7.18, 95% CI [-9.98 to 4.37], P < 0.01), and total Leicester Cough Questionnaire score (MD = 1.74, 95% CI [1.02 to 2.46], P < 0.01) exhibited between the P2X3 antagonist and placebo groups. The frequency of the night cough showed an insignificant difference between the two groups. According to the safety, drug-related adverse events, dysgeusia, hypogeusia, and ageusia significantly increased between the P2X3 antagonist and placebo groups. CONCLUSION: P2X3 receptor antagonists are promising drugs for treating chronic cough by significantly reducing the frequency, severity, and quality. Some potential side effects may include drug-related adverse events such as hypogeusia, ageusia, and dysgeusia.

Taste loss in cancer patients: clinicians' perceptions of educational materials and diagnostic tools.

PURPOSE: Cancer therapy is essential and lifesaving; however, it can have short- and long-term consequences on patients' health. Up to 87% of cancer patients report changes in taste function, yet patients report a lack of support from clinicians regarding their experience with taste loss during and following treatment. Thus, the objective of this study was to assess clinicians' knowledge and experience with managing patients with taste loss and identify potential gaps in the availability of educational materials and diagnostic tools. METHOD: In an online survey, sixty-seven participants who identify as clinicians and practice in the United States and work with cancer patients that complain of taste problems answered questions on their knowledge and experience supporting cancer patients experiencing changes in taste function and provided their opinion on access to educational materials. RESULTS: The current study reports gaps in participants' knowledge of taste and taste disorder terminology, with 15.4% correctly defining both taste and flavor and roughly half were familiar with specific taste disorder classifications. Over half of the participants reported not having access to adequate information to help their patients manage taste alterations. Only two-thirds of participants reported routinely asking patients if they are experiencing changes in taste function. CONCLUSION: Clinicians' responses emphasized the need to improve access to educational materials regarding taste changes and increase the availability of information regarding management strategies. Addressing these inequities in education and improving the standard of care is the first step in improving the care for cancer patients suffering from altered taste function.

Symptom profiles and their risk factors in patients with post-COVID-19 condition: a Dutch longitudinal cohort study.

BACKGROUND: To improve research and care for patients with post-COVID-19 condition more insight into different subtypes of post-COVID-19 condition and their risk factors is urgently needed. We aimed to identify risk factors of post-COVID-19 condition in general and for specific symptom profiles. METHODS: This study is based on data collected within the Lifelines Coronavirus disease 2019 (COVID-19) cohort (N = 76 503). Mean pre- and post-SARS-CoV-2 infection symptom scores were compared to classify post-COVID-19 condition. Latent Profile Analysis was used to identify symptom profiles. Logistic and multinomial regression analyses were used to examine the association between demographic, lifestyle and health-related risk factors and post-COVID-19 condition, and symptom profiles, respectively. RESULTS: Of the 3465 participants having had COVID-19, 18.5% (n = 642) classified for post-COVID-19 condition. Four symptom profiles were identified: muscle pain, fatigue, cardiorespiratory and ageusia/anosmia. Female sex was a risk factor for the muscle pain and fatigue profiles. Being overweight or obese increased risk for all profiles, except the fatigue profile. Having a chronic disease increased the risk for all profiles except the ageusia/anosmia profile, with the cardiorespiratory profile being only significant in case of multimorbidity. Being unvaccinated increased risk of the ageusia/anosmia profile. CONCLUSIONS: Findings from this study suggest that Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may trigger different pathophysiological mechanisms that may result in different subtypes of post-COVID-19 condition. These subtypes have shared and unique risk factors. Further characterization of symptom profiles and quantification of the individual and societal impact of specific symptom profiles are pressing challenges for future research.

Neurological and Psychiatric Manifestations of Post-COVID-19 Conditions.

BACKGROUND: We aimed to investigate the factors associated with neurological manifestations of post-coronavirus disease 2019 (COVID-19) conditions. METHODS: We retrospectively collected data from 440 patients who visited our post-COVID-19 clinic more than 4 weeks after severe acute respiratory syndrome coronavirus 2 infection. We analyzed the prevalence of different neurological symptoms (brain fog, memory impairment, headache, and dizziness) and assessed the associated factors. RESULTS: Brain fog was the most common symptom, observed in 170 patients (38.6%), followed by headaches (n = 137, 31.1%), dizziness (n = 128, 29%), and memory impairment (n = 104, 23.6%). Brain fog was associated with hyposmia or hypogeusia (odds ratio [OR], 2.54; P < 0.001), Fatigue Severity Scale (FSS) (OR, 1.06; P < 0.001), and Hospital Anxiety and Depression Scale-Anxiety (OR, 1.09; P = 0.037). Memory impairment was associated with sleep problems (OR, 2.83; P < 0.001), FSS (OR, 1.05; P < 0.001), and age (OR, 1.02; P = 0.015). Headache was associated with sleep problems (OR, 2.28; P = 0.001), sex (OR, 1.68; P = 0.042), and FSS (OR, 1.04; P < 0.001). Dizziness was associated with sleep problems (OR, 2.88; P < 0.001), and FSS (OR, 1.04; P < 0.001). The incidence of brain fog (P < 0.001), memory impairment (P < 0.001), dizziness (P = 0.007), and headache (P = 0.045) accompanied by hyposmia and hypogeusia was higher in patients with the aforementioned symptoms than in those without. CONCLUSION: This study suggests that there is a relationship between neurological symptoms and other clinical factors, such as fatigue, depression, anxiety, hyposmia, and hypogeusia.

Exploring brain functional connectivity in patients with taste loss: a pilot study.

PURPOSE: In a previous neuroimaging study, patients with taste loss showed stronger activations in gustatory cortices compared to people with normal taste function during taste stimulations. The aim of the current study was to examine whether there are changes in central-nervous functional connectivity in patients with taste loss. METHODS: We selected 26 pairs of brain regions related to taste processing as our regions of interests (ROIs). Functional magnetic resonance imaging (fMRI) was used to measure brain responses in seven patients with taste loss and 12 healthy controls as they received taste stimulations (taste condition) and water (water condition). The data were analysed using ROI-to-ROI functional connectivity analysis (FCA). RESULTS: We observed weaker functional connectivity in the patient group between the left and right orbitofrontal cortex in the taste condition and between the left frontal pole and the left superior frontal gyrus in the water condition. CONCLUSION: These results suggested that patients with taste loss experience changes of functional connectivity between brain regions not only relevant to taste processing but also to cognitive functions. While further studies are needed, fMRI might be helpful in diagnosing taste loss as an additional tool in exceptional cases.

Pure Sensory Lacunar Infarction in the Thalamus Presented as Bilateral Hypogeusia: A Case Report.

PURPOSE: While the gustatory pathway of animals has been well-researched, that of humans is still a mystery. Several theories have been established, and some earlier reports hypothesized the relation to laterality. However, some cases could not be fully explained by the laterality theory (1). To clarify the gustatory pathway, we reported a case with bilateral hypogeusia after right thalamic infarction. CASE: This 55-year-old, right-handed man suffered from sudden decreased sensitivity of taste. He was unable to differentiate sweetness and saltiness at bilateral anterior parts of tongue. Additionally, there was numbness at the upper palate and the lips. Neurological examination revealed decreased taste sense at both sides of his anterior tongue and decreased pin-prick sensation of the left part of his lips. Brain magnetic resonance imaging (MRI) revealed acute ischemic stroke at the right ventral posteromedial nucleus (VPM). Thus, single antiplatelet therapy was administered. Two weeks later, the symptoms improved significantly and completely recovered without sequelae. CONCLUSION: The exact gustatory pathway in humans remains uncertain nowadays. First, there were few reports about dysgeusia, which might be related to clinical neglect of taste deficits. Second, our knowledge of the human gustatory pathway depends solely on sporadic cases of taste-involved brain lesions. We reported a case of bilateral hypogeusia after right thalamic infarction. This finding indicates that, although there might be laterality of gustatory fibers to the left hemisphere, anatomical variations may exist in the human gustatory system. More research is needed to elucidate the understanding of the gustatory pathway in humans.

Diode laser in management of loss of taste sensation in patients with post-COVID syndrome: a randomized clinical trial.

OBJECTIVE: Loss of taste (ageusia) is a symptom observed following recovery from COVID-19 infection. The loss of taste and smell sensation may negatively affect patients' quality of life (QoL). The present study aimed to evaluate the effectiveness of the Diode Laser in managing loss of taste sensation in patients with post-COVID syndrome versus the placebo. MATERIAL AND METHOD: The study sample was 36 patients who complained of persistent loss of taste sensation following COVID-19. The patients were randomly assigned to one of the two groups according to the received treatment: Group I (laser treatment) and Group II (light treatment), with each patient receiving a diode laser treatment or placebo from the same operator. Taste sensation was subjectively measured after treatment for four weeks. RESULTS: The results demonstrated a significant difference between both groups regarding taste restoration after one month (p = 0.041), with Group II having a significantly higher percentage of cases 7 (38.9%) with partial taste restoration. In contrast, a significantly higher proportion of Group I 17 cases (94.4%) had complete taste restoration (p < 0.001). CONCLUSION: The present study concluded that using a Diode laser 810 nm aided in a more rapid recovery from loss of taste dysfunction.

Hyposmia in COVID-19: Temporal Recovery of Smell: A Preliminary Study.

Background and Objectives: Hypo/anosmia is a characteristic symptom of COVID-19 infection. The aim of this study is to investigate the time of smell recovery and to identify a possible order of perception recovery of different odors in COVID-19 patients. Materials and Methods: A prospective observational study was conducted on not hospitalized COVID-19 patients, selected according to eligible criteria. The study was approved by the Ethical Committee. A questionnaire formulated by our team was submitted to patients in order to know the duration of the hypo/anosmia and hypo/ageusia and the order of odor recovery: vanillin (mixed olfactory/gustatory substances), phenyl ethyl alcohol (rosewater) (pure olfactory substances), eucalyptol (mixed olfactory/trigeminal substances), and eugenol (mixed olfactory/trigeminal/gustatory substances). Results: 181 patients were included. Hypo/ageusia and hypo/anosmia lasted on average 10.25 (±8.26) and 12.8 (±8.80) days, respectively. The most frequent odor recovery sequence was: (1) phenyl ethyl alcohol; (2) eucalyptol; (3) vanillin; and (4) eugenol. In COVID-19 patients, hypo/anosmia occurs more often in women and at a young age. Conclusions: This preliminary investigation highlighted novel data: there is a chronological order in perception recovery of different olfactory substances and, therefore, in the restoration of the various sensitive nerve pathways involved in the sense of smell.