Disorders of smell and taste

Head and neck complications of cancer therapies: taste and smell

Sensory deficits affect awareness of the environment and information processing, leading to dysfunction that may have significant consequences. Deterioration of taste and/or smell sensation has been linked to impaired nutritional intake, and overall decreased quality of life (QoL). Recent data suggest that loss of these senses is also associated with cognitive decline and worse overall cancer treatment prognosis. Cancer therapies have commonly been associated with sensory deterioration. We review these associations with taste and smell in light of new findings and discuss potential prophylactic and therapeutic modalities for taste and smell function.

Cross-Cultural Validation of the Short Version of the Questionnaire of Olfactory Disorders-Negative Statements into Italian: Towards Personalized Patient Care

Given the high burden of olfactory dysfunction worldwide, recently increased due to the COVID-19 pandemic, it is mandatory to adopt a specific questionnaire to assess the impact of olfactory impairment on quality of life, to be used in clinical practice. The aim of this study is to adapt and validate the short version of the Questionnaire of Olfactory Disorders-Negative Statements (svQOD-NS) for Italian. In the pilot phase, the Italian version of the questionnaire (ITA-svQOD-NS) was produced following recommended guidelines. It was then given to 50 healthy subjects and 50 patients (affected by either nasal polyposis or septal deviation), and results were compared to those of other widely used questionnaires. Test-retest reliability was assessed on a sample of 25 patients. All 50 patients repeated the questionnaires at one and nine months after surgery. The internal consistency of ITA-svQOD-NS measured with Cronbach α was excellent (α = 0.92). The intraclass correlation coefficient for test-retest reliability was also optimal (0.93; 95%CI: 0.90-0.96). Concurrent validity tested with the Pearson coefficient was significant with all other tests administered; also, concerning responsiveness, statistically significant differences were obtained between pre- and post-operative conditions. ITA-svQOD-NS showed high internal consistency, test-retest reliability, and significant correlation with all most-used clinical questionnaires; thus, it can be efficiently applied to assess olfaction-related QoL in the Italian population.

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 Aetiology of Olfactory Dysfunction and Its Relationship to Diet Quality

People with olfactory loss may choose foods rich in sugar, salt and fat to compensate their loss—foods that constitute a Western-style diet (WSD). However, olfactory dysfunction has not been consistently linked to any particular type of dietary change. Here we considered whether the aetiology of olfactory dysfunction may affect consumption of a WSD. Two-hundred and twenty-two people with olfactory dysfunction of varying cause, were tested for chemosensory performance and their frequency of consumption of a WSD. There was no evidence of a link between a WSD and olfactory dysfunction at the aggregate level, but an aetiology-based approach revealed various patterns, showing both positive and negative associations between olfactory performance and consumption of a WSD. We suggest a number of reasons why, in certain cases, greater olfactory dysfunction may be linked to lower intakes of a WSD, and the role that different aetiologies may have in affecting choices for foods that may appeal following olfactory impairment.

SARS-CoV-2 Receptor ACE2 Is Enriched in a Subpopulation of Mouse Tongue Epithelial Cells in Nongustatory Papillae but Not in Taste Buds or Embryonic Oral Epithelium

As a result of the COVID-19 pandemic, evidence revealed that SARS-CoV-2 infection caused taste loss at a rate higher than that of influenza. ACE2, the entry receptor of SARS-CoV-2, has been identified in the oral epithelium; however, it is unclear at what developmental stage ACE2 expression emerges and whether ACE2 is expressed in taste buds. To identify the specific developmental stage, we analyzed RNA-Seq data from embryonic and newborn mouse oral tissue. We found that robust ACE2 expression was observed in the newborn oral epithelium. In contrast, only extremely low levels, if any, of ACE2 transcripts in the embryonic stage oral tissue were found (E12.5 and E14.5). Analyses of three public scRNA-seq data sets of adult mouse tongue epithelial cells showed that receptors for various viruses were enriched in distinct clusters of tongue epithelial cells. ACE2 was enriched in a subpopulation of epithelial cells in the basal region of nongustatory filiform papillae but not in the taste papillae or taste buds. Expression of ACE2 was detected in a small proportion of type III taste cells. Our results indicate that when applied across species, nongustatory papilla epithelial cells are the prime targets for SARS-CoV-2 infection in the tongue; thus, taste loss in COVID-19 patients is likely not caused by a direct infection of SARS-CoV-2 to taste bud cells. Additionally, fetuses at different stages of development may have distinct susceptibility to SARS-CoV-2 infection.

Assessment of the effect of inflammatory changes and allergic reaction on TAS2R38 receptor expression in patients with chronic sinusitis (CRS)

<b>Background:</b> Chronic rhinosinusitis (CRS) is one of the most common health complaints affecting 15% of the world's population. Recent reports confirm the participation of sensory organs in the defense process against pathogenic microorganisms. The bitter taste receptor TAS2R38 is described to play a role in the upper airway defense system. <br><b>Purpose:</b> The purpose of this study was to assess the function of the bitter taste receptor in correlation with the severity of CRS, sensory organ disorders and allergic reaction. <br><b>Material and method: </b>The study contained 100 patients undergoing nasal surgery, divided into two groups: CRS with and without nasal polyps. The control group consisted of patients undergoing septoplasty after excluding rhinosinusitis. Sinus mucosa samples obtained during surgery were used to assess TAS2R38 expression using immunohistochemistry. The IgE level was indicated from blood samples collected from patients. The Sniffin' Sticks Test was performed. <br><b>Results:</b> CRS patients had higher expression of TAS2R38 receptor compared to controls (p = 0.0175). A statistically significantly higher TAS2R38 H-score in nasal mucosa was found among patients with a higher inflammation process in CT scan (p = 0.001), higher IgE level (p = 0,04) and an abnormal result of the Sniffin' Sticks Test. <br><b>Conclusions: </b>Patients with CRS had significant TAS2R38 receptor overexpression correlating with the severity of inflammatory changes in CT scans, abnormal perception of smells and higher IgE level. A cumulative impact was found between the inflammatory changes, smell disfunction and the severity of subjective symptoms of CRS (according to EPOS) and the intensity of cell staining (index H-score).

Lipopolysaccharide-Induced Inflammatory Cytokine Expression in Taste Organoids

Inflammatory cytokines are signaling molecules that regulate numerous physiological processes, from tissue homeostasis to metabolism and food intake. Expression of certain cytokines can be markedly induced in subsets of taste bud cells under acute and chronic inflammation. This may contribute to altered taste perception and preference associated with many diseases. Although the pathways of cytokine induction are well studied in immune cells, they remain poorly characterized in taste cells, in part due to the difficulties of performing biochemical analyses with a limited number of taste cells. The recently developed taste organoid model provides an opportunity to carry out these mechanistic studies in vitro. However, it was unknown whether taste organoids respond to inflammatory stimuli as do in vivo native taste buds. Here we analyze lipopolysaccharide (LPS)-induced expression and secretion of two inflammatory cytokines, tumor necrosis factor (TNF), and interleukin-6 (IL-6). We show that, similarly to native mouse taste epithelia, organoids derived from mouse circumvallate stem cells express several toll-like receptors (TLRs), including TLR4-the primary receptor for LPS. Organoids and native taste epithelia express all five genes in the nuclear factor-κb (Nfkb) family that encode the transcription factor NF-κB, a critical regulator of inflammatory responses. LPS stimulates fast induction of TNF and IL-6 with similar induction kinetics in organoids and native taste epithelia. These results show that taste epithelial cells possess necessary components for inflammatory cytokine induction and secretion and suggest that the organoid model can be a useful tool to dissect the underlying mechanisms.

[Short term olfactory memory and olfactory function after inhalation anesthetic agents: a randomized clinical trial]

BACKGROUND AND OBJECTIVES

This clinical trial aimed to evaluate the effects of two different inhalation anesthetic agents on postoperative olfactory memory and olfactory function in patients who underwent micro laryngeal surgery.

METHODS

This randomized prospective controlled study consisted of 102 consecutive patients with a voice disorder. The patients underwent micro laryngeal surgery for voice disorders under general anesthesia. Patients who did not meet inclusion criteria and/or declined to participate (n=34) were excluded from the study. Patients were divided into two groups. Four patients from Group 1 and four patients from Group 2 were lost to follow-up. Group 1 (n=30) received sevoflurane, and Group 2 (n=30) received desflurane during anesthesia. We compared the results by performing the pre-op and post-op Connecticut Chemosensory Clinical Research Center Olfactory test.

RESULTS

Thirty-three patients (55%) were male and 27 (45%) were female. The mean age was 48.18±13.88 years (range: 19-70 years). Preoperative and postoperative olfactory functions did not show a significant difference within the groups postoperatively (p> 0.05). Preoperative and postoperative olfactory memory showed a significant decrease 3hours after the surgery (p <0.05).

CONCLUSIONS

Olfactory functions and memory were not affected by desflurane in the early postoperative period. Although sevoflurane did not affect olfactory functions, it had a temporary negative effect on olfactory memory in the early postoperative period.

Short term olfactory memory and olfactory function after inhalation anesthetic agents: a randomized clinical trial

Background and objectives

This clinical trial aimed to evaluate the effects of two different inhalation anesthetic agents on postoperative olfactory memory and olfactory function in patients who underwent micro laryngeal surgery.

Methods

This randomized prospective controlled study consisted of 102 consecutive patients with a voice disorder. The patients underwent micro laryngeal surgery for voice disorders under general anesthesia. Patients who did not meet inclusion criteria and/or declined to participate (n = 34) were excluded from the study. Patients were divided into two groups. Four patients from Group 1 and four patients from Group 2 were lost to follow-up. Group 1 (n = 30) received sevoflurane, and Group 2 (n = 30) received desflurane during anesthesia. We compared the results by performing the pre-op and post-op Connecticut Chemosensory Clinical Research Center Olfactory test.

Results

Thirty-three patients (55%) were male and 27 (45%) were female. The mean age was 48.18 ± 13.88 years (range: 19‒70 years). Preoperative and postoperative olfactory functions did not show a significant difference within the groups postoperatively (p > 0.05). Preoperative and postoperative olfactory memory showed a significant decrease 3 hours after the surgery (p < 0.05).

Conclusions

Olfactory functions and memory were not affected by desflurane in the early postoperative period. Although sevoflurane did not affect olfactory functions, it had a temporary negative effect on olfactory memory in the early postoperative period.

Immune Responses Alter Taste Perceptions: Immunomodulatory Drugs Shape Taste Signals during Treatments

Considering that nutrients are required in health and diseases, the detection and ingestion of food to meet the requirements is attributable to the sense of taste. Altered taste sensations lead to a decreased appetite, which is usually one of the frequent causes of malnutrition in patients with diseases. Ongoing taste research has identified a variety of drug pathways that cause changes in taste perceptions in cancer, increasing our understanding of taste disturbances attributable to aberrant mechanisms of taste sensation. The evidence discussed in this review, which addresses the implications of innate immune responses in the modulation of taste functions, focuses on the adverse effects on taste transmission from taste buds by immune modulators responsible for alterations in the perceived intensity of some taste modalities. Another factor, damage to taste progenitor cells that directly results in local effects on taste buds, must also be considered in relation to taste disturbances in patients with cancer. Recent discoveries discussed have provided new insights into the pathophysiology of taste dysfunctions associated with the specific treatments. SIGNIFICANCE STATEMENT: The paradigm that taste signals transmitted to the brain are determined only by tastant-mediated activation via taste receptors has been challenged by the immune modification of taste transmission through drugs during the processing of gustatory information in taste buds. This article reports the findings in a model system (mouse taste buds) that explain the basis for the taste dysfunctions in patients with cancer that has long been observed but never understood.

Diseases of the nasal cavity

Despite garnering minimal attention from the medical community overall, olfaction is indisputably critical in the manner in which we as humans interact with our surrounding environment. As the initial anatomical structure in the olfactory pathway, the nasal airway plays a crucial role in the transmission and perception of olfactory stimuli. The goal of this chapter is to provide a comprehensive overview of olfactory disturbances as it pertains to the sinonasal airway. This comprises an in-depth discussion of clinically relevant nasal olfactory anatomy and physiology, classification systems of olfactory disturbance, as well as the various etiologies and pathophysiologic mechanisms giving rise to this important disease entity. A systematic clinical approach to the diagnosis and clinical workup of olfactory disturbances is also provided in addition to an extensive review of the medical and surgical therapeutic modalities currently available.

Effects of isotretinoin on the olfactory function in patients with acne

Background:

Isotretinoin is a synthetic analog of vitamin A. Recent studies support a role for retinoic acid in the recovery of olfactory function following injury in mice.

Objective:

This study aimed at determining the effect of isotretinoin on olfactory function in patients who have acne and are otherwise healthy.

Methods:

Forty-five patients (aged 25-40 years) with acne were included in the study. All patients underwent a rhinological examination. Olfactory function was assessed by the Sniffin' Sticks Test. The test was assessed at baseline and in the third month of isotretinoin treatment.

Results:

Isotretinoin improved the performance of patients in the olfactory test. The SST score increased from 8.7±1.09 to 9.5±1.19 (p<0.001), prevalence of hyposmia decreased from 40% to 24% and normosmia increased from 60% to 75% (p=0.059). The percentage of patients whose olfactory function was categorized as "good" increased from 6% to 21.3%. This increase was statistically significant (p<0.05).

Study limitations:

Absence of a control group is one of the limitations of this study. Also, we did not evaluate patients with smell test after stopping isotretinoin treatment.

Conclusion:

We examined the effect of systemic isotretinoin on olfactory function. It can be concluded from the present investigation that isotretinoin therapy improves the sense of smell.

Nitrogen dioxide pollution exposure is associated with olfactory dysfunction in older U.S. adults

BACKGROUND

Olfactory dysfunction has profound effects on quality of life, physical and social function, and mortality itself. Nitrogen dioxide (NO2 ) is a pervasive air pollutant that is associated with respiratory diseases. Given the olfactory nerve's anatomic exposure to airborne pollutants, we investigated the relationship between NO2 exposure and olfactory dysfunction.

METHODS

The ability to identify odors was evaluated using a validated test in respondents from the National Social Life, Health, and Aging Project (NSHAP), a representative probability sample of home-dwelling, older U.S. adults age 57 to 85 years. Exposure to NO2 pollution was assessed using measurements obtained from the U.S. Environmental Protection Agency (EPA) Aerometric Information Retrieval System (AIRS) ambient monitoring site closest to each respondent's home. We tested the association between NO2 exposure and olfactory dysfunction using multivariate logistic regression.

RESULTS

Among older adults in the United States, 22.6% had impaired olfactory function, defined as ≤3 correct (out of 5) on the odor identification test. Median NO2 exposure during the 365 days prior to the interview date was 14.7 ppb (interquartile range [IQR], 10.8 to 19.7 ppb). An IQR increase in NO2 exposure was associated with increased odds of olfactory dysfunction (OR, 1.35; 95% CI, 1.07 to 1.72), adjusting for age, gender, race/ethnicity, education, cognition, comorbidity, smoking, and season of the home interview (n = 1823).

CONCLUSION

We show for the first time that NO2 exposure is associated with olfactory dysfunction in older U.S. adults. These results suggest an important role for NO2 exposure on olfactory dysfunction, and, potentially, nasal disease more broadly.

Fine particulate matter exposure and olfactory dysfunction among urban-dwelling older US adults

OBJECTIVES

The olfactory nerve is anatomically susceptible to injury from pollution in inspired air, but there are no large-scale epidemiologic studies investigating this relationship.

METHODS

Cross-sectional study using data from the National Social Life, Health, and Aging Project, a representative sample of home-dwelling US adults age 57-85 years. Olfactory function was tested using a validated 5-item odor identification test (Sniffin' Sticks). Exposure to fine particulate matter (PM_2.5) at each respondent's home was estimated as 1-12 month moving averages prior to olfactory assessment using validated spatio-temporal models.

RESULTS

Olfactory dysfunction was significantly associated with PM_2.5 exposures averaged over 3-12 months in urban-dwelling respondents. The strongest effect was for 6 month average exposure (per 1-IQR increase in PM_2.5: OR 1.28, 95% CI 1.05, 1.55) adjusting for age, gender, race/ethnicity, education, cognition, comorbidity, smoking, and the season. Interestingly, the most deleterious effects were observed among the youngest respondents, 57-64 years old, and those living in the northeast and south.

CONCLUSIONS

We show for the first time that air pollution exposure is associated with poor olfaction among urban-living, older US adults.

Role of ortho-retronasal olfaction in mammalian cortical evolution

Fossils of mammals and their extinct relatives among cynodonts give evidence of correlated transformations affecting olfaction as well as mastication, head movement, and ventilation, and suggest evolutionary coupling of these seemingly separate anatomical regions into a larger integrated system of ortho-retronasal olfaction. Evidence from paleontology and physiology suggests that ortho-retronasal olfaction played a critical role at three stages of mammalian cortical evolution: early mammalian brain development was driven in part by ortho-retronasal olfaction; the bauplan for neocortex had higher-level association functions derived from olfactory cortex; and human cortical evolution was enhanced by ortho-retronasal smell.

Intensity and pleasantness of sucrose taste in patients with winter depression

OBJECTIVES

Increased consumption of carbohydrates and craving for sweets are considered core features of winter depression. Unfortunately, little is known about neural and behavioral correlates of these symptoms. The primary aim of the present study was to evaluate taste responses to sucrose solutions in depressed patients with seasonal affective disorder (SAD).

METHODS

Intensity and pleasantness ratings of sucrose solutions, electrogustometric thresholds, and taste identification abilities were assessed in depressed patients with SAD and non-seasonal affective disorder (non-SAD), and in non-depressed controls.

RESULTS

Electrogustometric thresholds and identification abilities did not differ between the study groups. There were no differences between the groups in intensity or pleasantness ratings of sucrose solutions (1-30%). The proportion of 'sweet likers', i.e. subjects rating the highest sucrose concentration as most pleasant, was similar in the controls, SAD, and non-SAD patients.

DISCUSSION

The present results suggest that: (i) winter depression is not associated with major alterations in gustatory function; and (ii) sweet craving and increased consumption of carbohydrates in patients with winter depression is not secondary to altered responses to sweet tastants. More studies are needed to characterize hedonic responses of patients with SAD to other sweet and non-sweet foods.

Conductive olfactory losses in chronic rhinosinusitis? A computational fluid dynamics study of 29 patients

BACKGROUND

Besides sensorineural factors, conductive impediments likely contribute to olfactory losses in chronic rhinosinusitis (CRS) patients, yet no conclusive evidence exists. We aimed to examine possible conductive factors using computational fluid dynamics (CFD) models.

METHODS

A total of 29 CRS patients were assessed via odorant detection thresholds (ODTs), rhinomanometry (nasal resistance [NR]), acoustic rhinometry (minimum-cross-sectional area [MCA]) and computed tomography (CT) staging. CFD simulations of nasal airflow and odorant absorption to olfactory region were carried out based on individual CTs. Biopsies of olfactory epithelium (OE) were collected, cryosectioned, stained, and scored for erosion.

RESULTS

Significant correlations to ODTs were found for 3 variables: odor absorption in the olfactory region (r = -0.60, p < 0.01), MCA (r = -0.40, p < 0.05), and CT staging (r = 0.42, p < 0.05). However, significant findings were limited to ODTs of the highly soluble l-carvone. Multiple regression analysis revealed that these variables combined, with the addition of NR, can account for 65% of the total variance in ODTs. CT staging correlated significantly with OE erosion (r = 0.77, p < 0.01) and can replace the latter in the regression with comparable outcomes. Partial correlations suggest the contributions of both conductive and sensorineural variables are more prominent if adjusted for the effects of the other. Olfactory loss and inflammatory factors have strong bilateral involvement, whereas conductive factors are independent between sides. As validation, CFD-simulated NRs significantly correlated with rhinomanometrically assessed NRs (r = 0.60, p < 0.01).

CONCLUSION

Both conductive and sensorineural mechanisms can contribute to olfactory losses in CRS. CFD modeling provides critical guidance in understanding the role of conductive impediments in olfactory dysfunction in CRS.

Taste bud homeostasis in health, disease, and aging

The mammalian taste bud is an onion-shaped epithelial structure with 50-100 tightly packed cells, including taste receptor cells, supporting cells, and basal cells. Taste receptor cells detect nutrients and toxins in the oral cavity and transmit the sensory information to gustatory nerve endings in the buds. Supporting cells may play a role in the clearance of excess neurotransmitters after their release from taste receptor cells. Basal cells are precursor cells that differentiate into mature taste cells. Similar to other epithelial cells, taste cells turn over continuously, with an average life span of about 8-12 days. To maintain structural homeostasis in taste buds, new cells are generated to replace dying cells. Several recent studies using genetic lineage tracing methods have identified populations of progenitor/stem cells for taste buds, although contributions of these progenitor/stem cell populations to taste bud homeostasis have yet to be fully determined. Some regulatory factors of taste cell differentiation and degeneration have been identified, but our understanding of these aspects of taste bud homoeostasis remains limited. Many patients with various diseases develop taste disorders, including taste loss and taste distortion. Decline in taste function also occurs during aging. Recent studies suggest that disruption or alteration of taste bud homeostasis may contribute to taste dysfunction associated with disease and aging.

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

PURPOSE

To describe systematic methods developed over 40 years among over 5000 patients at The Taste and Smell Clinic in Washington, DC to evaluate taste and smell dysfunction.

MATERIALS AND METHODS

A tripartite methodology was developed. First, methods to determine clinical pathology underlying the multiple disease processes responsible for taste and smell dysfunction were developed. Second, methods to determine biochemical parameters responsible for these pathologies were developed. Third, methods to implement these techniques were developed to form a unified basis upon which treatment strategies can be developed to treat these patients.

RESULTS

Studies were performed in 5183 patients. Taste loss was present in 62% of patients, smell loss in 87%. Most patients with taste loss (52%) exhibited Type II hypogeusia; most patients with smell loss (56%) exhibited Type II hyposmia. Sensory distortions were present in 60%. Four common diagnostic entities were found: post influenza-type hyposmia and hypogeusia (27% of patients), idiopathic causes (16%), allergic rhinitis (15%) and post head injury (14%). Regardless of clinical diagnosis the major biochemical abnormality found in most patients (~70%) was diminished parotid salivary and nasal mucus secretion of cAMP and cGMP.

CONCLUSIONS

Taste and smell dysfunctions are common clinical problems associated with chronic disease processes. These symptoms require a systematic, integrated approach to understand their multiple and complex components. The approach presented here can and has led to effective treatment.

Development of a new method using narrow band imaging for taste assessment

OBJECTIVES/HYPOTHESIS

The observation of fungiform papillae is a useful objective taste examination. The purpose of this study is to develop a new method using narrow band imaging for assessment of taste function.

STUDY DESIGN

Using a narrow band imaging endoscope, we assessed the number and blood vessel morphology of fungiform papillae and compared with the gustatory threshold by the filter paper disc test.

METHODS

The number of fungiform papillae was counted in 20 mm(2) , and blood vessels in fungiform papillae were evaluated morphologically by a five-point scoring system in 11 patients who had undergone middle ear surgery. The filter taste disc test was performed simultaneously to obtain the gustatory threshold and was compared with the number and blood vessel morphology of fungiform papillae.

RESULTS

Using a narrow band imaging endoscope, we could clearly detect not only fungiform papillae but also blood vessel morphology. There was a significant correlation between the values of the number of papillae and blood vessel morphology. Moreover, these two parameters revealed a significant inverse correlation with gustatory function. As expected, both parameters on the affected side were significant lower than those on the unaffected side in patients.

CONCLUSIONS

The assessment of fungiform papillae using narrow band imaging endoscopy is easy, highly sensitive, and reliable; therefore, it might be useful as an objective examination of taste function.

LEVEL OF EVIDENCE

N/A.

An investigational report into the causes of pine mouth events in US consumers

Between July 2008 and June 2012, the US Food and Drug Administration received 501 consumer reports of prolonged taste disturbances consistent with pine mouth syndrome. Consumers consistently reported a delayed bitter or metallic taste beginning hours to days following consumption of pine nuts that recurred with intake of any food or meal. This dysgeusia lasted in some cases up to a few weeks, but would eventually resolve without serious health consequences. To evaluate these reports, a questionnaire was developed to address various characteristics of the pine nuts consumed, pertinent medical history of complainants and other dysgeusia-related factors. Pine nut samples associated with 15 complaints were collected for analysis. The investigation of reports found no clear evidence of an underlying medical cause or common trigger that could adequately explain the occurrence of dysgeusia in complainants. Rather, the results of our investigation suggest that the occurrence of "pine mouth syndrome" in US consumers is correlated with the consumption of the pine nut species Pinus armandii.

Sweet liking in patients with Parkinson's disease

Pleasant tastes and odors are considered phylogenetically old natural rewards and their hedonic evaluation is regarded as a good indicator of the reward system function. The primary aim of the present study was to compare pleasantness ratings of sucrose solutions (1-30%, w/w) and sweet liking/disliking status in 20 patients with Parkinson's disease (PD) and in 20 age-matched healthy controls. In addition, basic sensory aspects of gustatory (intensity ratings, electrogustometric thresholds) and olfactory function (identification abilities in the Sniffin' Stick test) were assessed in both groups. The number of odors rated as pleasant, unpleasant, and neutral was also compared. As expected, the PD patients showed a significant impairment in olfactory identification abilities. There were no differences between the PD patients and controls in electrogustometric thresholds. Rated intensity of higher sucrose concentrations did not differ between the groups. The PD patients tended to rate water taste as more intense in comparison with the controls. Pleasantness ratings of sucrose solutions, the proportion of subjects rating 30% sucrose as the most pleasant (sweet likers), and the number of odors rated as pleasant did not differ between the study groups. The present results suggest that PD does not lead to any obvious alterations in pleasantness ratings of chemosensory stimuli. The study requires replication in larger samples.

Anosmia after exposure to a pyrethrin-based insecticide: a case report

We present the case of a subject developing anosmia, preceded by nasal transient irritation and short lasting phantosmia and torqosmia, upon re-entrance into a room treated with a pyrethrin-based insecticide. The concentration of the insecticide in the room is unknown, but relatively high levels are predicted basing upon the modality of exposure and by the irritation symptoms in the subject. Despite corticosteroids therapy, anosmia has persisted unmodified for more than three years; according to, and based on evidence in the literature on olfactory disturbance prognosis, anosmia in this patient is likely to be permanent. The significance of this case report is related to the current wide use of insecticides containing pyrethrin and pyrethroids and highlights the need for more adequate attention to lowering airborne concentrations of pyrethrins and pyrethroids prior to re-entering the treated rooms. In particular, in a closed space sprayed with pyrethrins and pyrethroids insecticide, any irritant symptoms and/or dysosmia should be immediately considered relevant warning signs, and must be avoided.

Effects of statins on the recovery of olfactory function in a 3-methylindole-induced anosmia mouse model

BACKGROUND

Despite the importance of olfactory function, no effective medications have been identified to treat olfactory disorders. This study was performed to evaluate the functional recovery of olfaction damaged by 3-methylindole (3MI) in a mouse model with hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins).

METHODS

In a randomized placebo-controlled trial, 24 healthy female BALB/c mice (aged 9-10 weeks and weighing 18-20 g each) were randomly allocated to statin-treated or control groups. Olfactory loss was induced by i.p. injections of 3MI. Atorvastatin (10 mg/kg) or normal saline was then administered per os with a gastric tube for 3 weeks. The effects of treatment were evaluated by food-finding tests and Western blot analysis.

RESULTS

Both groups showed complete losses of olfactory function 1 week after 3MI injection. Three weeks after 3MI injection, 9 of the 12 mice in the statin-treated group (75%) passed a food-finding test, in which they were able to find the food within 3 minutes, at least two times out of three trials. However, only two mice in the control group (16.6%) passed the food-finding test, and this difference was statistically significant (p = 0.004; chi-square test). The expression level of the olfactory marker protein was also elevated in the statin-treated group (p = 0.030; Wilcoxon rank sum test).

CONCLUSION

Statins are associated with recovery of olfaction after 3MI injection in a mouse model.

Smell and taste disorders

Olfaction and taste promote satisfaction and protection in daily life. The astute facial plastic surgeon recognizes the importance of a baseline smell test to document the patients' olfactory status before surgery. After surgery, the surgeon must be alert to the possible mechanisms of hyposmia and anosmia and the pertinent treatment strategies. The surgeon must also understand the importance of counseling the patient and family regarding the cause of the dysfunction and the proper treatments. This article updates the facial plastic surgeon on the importance of smell and taste and associated disorders with a current review of the literature.

Breaking paradigms: a new definition for halitosis in the context of pseudo-halitosis and halitophobia

It is known that almost one-third of patients who seeks treatment for bad breath do not have genuine halitosis. Halitosis can occur even in cases when the malodor is not perceived by those around the patient and can neither be confirmed by organoleptic tests, nor by sulfur portable monitor readings. In such cases, these patients have been considered as halitophobic or have pseudo-halitosis. The complaint might signal the existence of a chemosensory dysfunction. Factors associated with taste and smell perception can be potentially connected to the occurrence of oral malodor. The threshold values of volatile sulfur compounds that have been used to establish the diagnosis of genuine halitosis do not take into account that the patient may perceive low levels of these and of other volatile compounds through retronasal olfaction. The current concept of halitosis requires the presence of a signal that has been based on equipment results, from the olfactory perception of the examiners and of those who interact with the patient. Nevertheless, the concept does not encompass the symptoms of halitosis. This paper addresses some of the possible causes of chemosensory dysfunction and proposes a new definition for halitosis.

Taste evaluation in adolescents and pediatric patients with benign migratory glossitis

OBJECTIVE

Benign migratory glossitis (BMG) is a disease that affects the tongue and is considered an inflammatory disorder well recognized. It is characterized by the appearance of erosive areas on the dorsum and lateral border of the tongue that can be isolated or multiple. The aim of this study was to assess whether the perception of taste to the four basic tastes is altered due to the presence of BMG.

METHODS

Forty individuals of both sexes with a mean age of 12.1 years were divided into two groups (20 BMG patients and 20 healthy controls) and had their taste function assessed in relation to four basic tastes: bitter, sour, sweet, and salty.

RESULTS

All participants in the case group exhibited lesions over the dorsum, edges and tip of the tongue with a possible extension to the surface below. No statistic difference was observed between BMG patients and controls for the taste scores (Mann-Whitney U test: P=0.0955). The percentage of correctly identified taste strips for the highest concentrations was 100% for all tastes. For the lowest concentrations it was 85% for sweet, 50% for sour, 95% for salty, and 95% for bitter. Three patients with BMG and three control subjects showed hypogeusia.

CONCLUSION

This study revealed that BMG is not able to change the perception of taste for salty, sweet, sour and bitter.

A Pilot Study of Taste Changes Among Hospice Inpatients With Advanced Cancer

Identification of taste abnormalities can help understand difficulties in nutrition. We evaluated 15 hospice inpatients with advanced cancer for subjective taste changes. The majority had both subjective and objective taste changes. Most thought all food was tasteless followed by loss of sweet sensation and meat aversion. About half of the participants exhibited anorexia and weight loss with decreased energy intake. Both detection and recognition thresholds for these basic tastes were abnormal for the majority of participants. Reduced sensitivity for sweet and salt taste and altered perception for sour predominated in formal taste testing.

Effects of statins on regeneration of olfactory epithelium

BACKGROUND

This study was performed to investigate whether statins can enhance the recovery of the olfactory epithelium (OE) damaged by 3-methylindole (3MI), an olfactotoxicant, and to compare the effects with those of steroids.

METHODS

Randomized placebo-controlled trial was performed. Fifty-four healthy female Sprague-Dawley rats (aged 9-10 weeks and weighing 160-180 g each) were randomly allocated to the statin-treated, steroid-treated, or control groups. Olfactory loss was induced using i.p. injection of 3MI in adult rats. Atorvastatin (10 mg/kg for 4 weeks), prednisolone (1 mg/kg for 2 weeks), or normal saline (1 cc for 4 weeks) was then administered per os with a gastric tube. Hematoxylin and eosin (H&E) staining and immunohistochemical staining were performed to evaluate the change of thickness and the arrangement of the OE, and immunoreactivity to protein gene product (PGP) 9.5 and proliferating cell nuclear antigen (PCNA).

RESULTS

The statin-treated group showed the earliest increase of the thickness of the OE (p = 0.002 at 7 days after 3MI injection) and the immunoreactivity to PCNA (p = 0.032 at 7 days after 3MI injection) among the three groups. The immunoreactivity to PGP 9.5 showed significantly better improvement at the 7th and 28th days after 3MI injection compared with the steroid-treated or control groups (p = 0.002 and p < 0.001, respectively).

CONCLUSION

Statins might enhance the proliferation and neuroregenesis of the OE after 3MI injection.

Inflammation and taste disorders: mechanisms in taste buds

Taste disorders, including taste distortion and taste loss, negatively impact general health and quality of life. To understand the underlying molecular and cellular mechanisms, we set out to identify inflammation-related molecules in taste tissue and to assess their role in the development of taste dysfunctions. We found that 10 out of 12 mammalian Toll-like receptors (TLRs), type I and II interferon (IFN) receptors, and their downstream signaling components are present in taste tissue. Some TLRs appear to be selectively or more abundantly expressed in taste buds than in nongustatory lingual epithelium. Immunohistochemistry with antibodies against TLRs 1, 2, 3, 4, 6, and 7 confirmed the presence of these receptor proteins in taste bud cells, of which TLRs 2, 3, and 4 are expressed in the gustducin-expressing type II taste bud cells. Administration of TLR ligands, lipopolysaccharide, and double-stranded RNA polyinosinic:polycytidylic acid, which mimics bacterial or viral infection, activates the IFN signaling pathways, upregulates the expression of IFN-inducible genes, and downregulates the expression of c-fos in taste buds. Finally, systemic administration of IFNs augments apoptosis of taste bud cells in mice. Taken together, these data suggest that TLR and IFN pathways function collaboratively in recognizing pathogens and mediating inflammatory responses in taste tissue. This process, however, may interfere with normal taste transduction and taste bud cell turnover and contributes to the development of taste disorders.

Gustatory and olfactory function in patients with unipolar and bipolar depression

Although the crucial distinction between unipolar depressive disorder and bipolar disorder is the presence of mania (or hypomania) in the course of the latter, significant differences between unipolar and bipolar depression have also been found in clinical studies. The primary aim of the present investigation was to assess pleasantness/unpleasantness ratings of chemosensory stimuli in depressed patients, including subjects with unipolar and bipolar depression. Sensory aspects (thresholds and identification abilities) of gustatory and olfactory function were also assessed. There were no major differences between a depression group, as a whole, and healthy controls in terms of gustatory and olfactory thresholds and identification abilities. Similarly, pleasantness ratings of various gustatory and olfactory stimuli did not differ between the control and depression group. Gustatory and olfactory thresholds and identification abilities did not differ between individuals with unipolar and bipolar depression. Bipolar patients tended to rate less gustatory stimuli as unpleasant and more olfactory stimuli as pleasant compared to unipolar patients. The present results suggest that: i) depression is not associated with any major deficit in sensory aspects of gustatory and olfactory function or altered hedonic ratings of chemosensory stimuli; ii) hedonic responses to chemosensory stimuli tend to be increased in bipolar as compared to unipolar depressed patients.

Immune cells of the human peripheral taste system: dominant dendritic cells and CD4 T cells

Taste loss or alterations can seriously impact health and quality of life due to the resulting negative influence on eating habits and nutrition. Infection and inflammation are thought to be some of the most common causes of taste perception disorders. Supporting this view, neuro-immune interactions in the peripheral gustatory system have been identified, underlying the importance of this tissue in mucosal immunity, but we have little understanding of how these interactions influence taste perception directly or indirectly. This limited understanding is evident by the lack of even a basic knowledge of the resident immune cell populations in or near taste tissues. The present study characterized the distribution and population of the major immune cells and their subsets in healthy human anterior, lingual, fungiform papillae (FP) using immunohistochemistry. Dendritic cells (DCs) were the predominant innate immune cells in this tissue, including four subtypes: CD11c(+) DCs, DC-SIGN+ immature DCs, CD83(+) mature DCs, and CD1a(+) DCs (Langerhans cells). While most DCs were localized beneath the lamina propria and only moderately in the epithelium, CD1a(+) Langerhans cells were exclusively present within the epithelium and not in sub-strata. A small number of macrophages were observed. T lymphocytes were present throughout the FP with CD4(+) T cells more prevalent than CD8(+) T cells. Very few CD19(+) B lymphocytes were detected. The results show that DCs, macrophages, and T lymphocytes are the constitutive guardians of human FP taste tissue, with DCs and CD4 T cells being dominant, while B lymphocytes are rare under normal, healthy conditions. These observations provide a basic anatomical foundation for the immune response in the healthy human tongue as a basis for subsequent disease-related studies, but none of the present data indicate that the immune cell populations identified are, in fact, altered in individuals with abnormal taste perception.

Depressive symptoms and olfactory function in older adults

AIMS

Neuroimaging studies suggest a significant overlap between brain regions involved in the regulation of olfaction and mood. The aim of the present study was to search for correlations between depressive symptomatology measured by the 15-item Geriatric Depression Scale (GDS) and olfactory function assessed with Sniffin' Sticks in non-demented older adults (aged 53-79 years).

METHODS

Taste detection thresholds were also measured by means of electrogustometry on the anterior tongue.

RESULTS

No correlation was found between the GDS scores (range: 0-12) and olfactory thresholds or olfactory identification scores. Similarly, there was no relationship between depressive symptoms and electrogustometric thresholds. Subjects (n = 25) scoring > or = 5 on the GDS were classified as 'depressed' and all other individuals (n = 60) were classified as 'non-depressed'. The two groups did not differ in terms of the olfactory measures and electrogustometric threshold.

CONCLUSION

Depressive symptoms are not associated with any major olfactory deficit in non-clinical older adults.

[Taste and smell senses estimation in patients with nasal polyps]

AIM

The purpose of this study was estimation of taste and smell senses functioning in patients with nasal polyps and the analysis of correlation between taste and smell perception threshold and polyps size.

MATERIAL AND METHOD

The study included 86 persons. The 35 of them were patients of Otolaryngology Department of Warsaw Military Institute with nasal polyps diagnosis. There were 51 healthy people as a control group. The smell perception examination was performed using Elsberg-Levy method in Pruszewicz modification. The gustatory function was investigated using gustatory method by Börstein and electrogustometry. The Börstein method based on four substances (each of them in three increasing concentrations) related to four basic tastes: sweet (glucose), bitter (chininum hydrochloride), sour (citric acid) and salty (sodium chloride). The taste feeling threshold (POS), that meant the lowest concentration of each solution being correctly recognized by a person, was noticed for each taste. For quantitative estimation of taste perception threshold we included impulse electrogustometry with bipolar electrode.

RESULTS

In our study the taste disturbances were observed, depending on kind of taste, in 20-70% cases in gustometry and for 13 patients in electrogustometry. Abnormal olfactory results we diagnosed in more then 57% patients. We did not confirmed correlation between taste perception threshold and polyps size but polyps size influenced on olfactory results.

CONCLUSIONS

Smell and taste disturbances are very often symptoms of nasal polyposis. The taste and olfactory estimation ought to be integral part of routine patient examination in otolaryngology department.

Olfactory cilia: our direct neuronal connection to the external world

An organism's awareness of its surroundings is dependent on sensory function. As antennas to our external environment, cilia are involved in fundamental biological processes such as olfaction, photoreception, and touch. The olfactory system has adapted this organelle for its unique sensory function and optimized it for detection of external stimuli. The elongated and tapering structure of olfactory cilia and their organization into an overlapping meshwork bathed by the nasal mucosa is optimized to enhance odor absorption and detection. As many as 15-30 nonmotile, sensory cilia on dendritic endings of single olfactory sensory neurons (OSNs) compartmentalize signaling molecules necessary for odor detection allowing for efficient and spatially confined responses to sensory stimuli. Although the loss of olfactory cilia or deletion of selected components of the olfactory signaling cascade leads to anosmia, the mechanisms of ciliogenesis and the selected enrichment of signaling molecules remain poorly understood. Much of our current knowledge is the result of elegant electron microscopy studies describing the structure and organization of the olfactory epithelium and cilia. New genetic and cell biological approaches, which compliment these early studies, show promise in elucidating the mechanisms of olfactory cilia assembly, maintenance, and compartmentalization. Importantly, emerging evidence suggests that olfactory dysfunction represents a previously unrecognized clinical manifestation of multiple ciliary disorders. Future work investigating the mechanisms of olfactory dysfunction combining both clinical studies with basic science research will provide us important new information regarding the pathogenesis of human sensory perception diseases.

Inflammation activates the interferon signaling pathways in taste bud cells

Patients with viral and bacterial infections or other inflammatory illnesses often experience taste dysfunctions. The agents responsible for these taste disorders are thought to be related to infection-induced inflammation, but the mechanisms are not known. As a first step in characterizing the possible role of inflammation in taste disorders, we report here evidence for the presence of interferon (IFN)-mediated signaling pathways in taste bud cells. IFN receptors, particularly the IFN-gamma receptor IFNGR1, are coexpressed with the taste cell-type markers neuronal cell adhesion molecule and alpha-gustducin, suggesting that both the taste receptor cells and synapse-forming cells in the taste bud can be stimulated by IFN. Incubation of taste bud-containing lingual epithelia with recombinant IFN-alpha and IFN-gamma triggered the IFN-mediated signaling cascades, resulting in the phosphorylation of the downstream STAT1 (signal transducer and activator of transcription protein 1) transcription factor. Intraperitoneal injection of lipopolysaccharide or polyinosinic:polycytidylic acid into mice, mimicking bacterial and viral infections, respectively, altered gene expression patterns in taste bud cells. Furthermore, the systemic administration of either IFN-alpha or IFN-gamma significantly increased the number of taste bud cells undergoing programmed cell death. These findings suggest that bacterial and viral infection-induced IFNs can act directly on taste bud cells, affecting their cellular function in taste transduction, and that IFN-induced apoptosis in taste buds may cause abnormal cell turnover and skew the representation of different taste bud cell types, leading to the development of taste disorders. To our knowledge, this is the first study providing direct evidence that inflammation can affect taste buds through cytokine signaling pathways.

Diagnosis and management of olfactory disorders: survey of UK-based consultants and literature review

Background:

The diagnosis and management of olfactory disorders is an often neglected topic in otolaryngology. This article evaluates current clinical practice within the United Kingdom, and provides a literature-based review of the diagnosis, management and prognosis of olfactory pathology.

Design:

A questionnaire was sent to consultant and associate specialist members of the British Association of Otolaryngologists and Head and Neck Surgeons. The responses were documented to gain an impression of how olfactory disorders are managed in the United Kingdom. The literature relating to olfactory dysfunction was then evaluated and the findings summarised.

Conclusions:

Management of olfactory pathology varies across the United Kingdom. The literature suggests that chemosensory testing is optimal and that both forced-choice and threshold testing should be applied if objective evaluation is required. Imaging can be of value but the appropriate technique should be used. Olfactory function can recover following head injury, viral infection and chronic sinonasal disease, although varying degrees of dysfunction are likely to persist. There is a role for the use of corticosteroids, particularly when administered systemically. More research is needed to establish the appropriate dose and length of treatment.

Numerical modeling of nasal obstruction and endoscopic surgical intervention: outcome to airflow and olfaction

BACKGROUND

Mechanical obstruction of odorant flow to the olfactory neuroepithelium may be a primary cause of olfactory loss in nasal-sinus disease patients. Surgical removal of nasal obstruction may facilitate the recovery of olfactory ability. Unfortunately, quantifying the functional impact of nasal obstruction and subsequent surgical outcomes using acoustic rhinometry, rhinomanometry, or CT scans is inadequate.

METHODS

Using computational fluid dynamics (CFD) techniques, we can convert patient CT scans into anatomically accurate 3D numerical nasal models that can be used to predict nasal airflow and odorant delivery rates. These models also can be rapidly modified to reflect anatomic changes, e.g., surgical removal of polyps.

RESULTS

CFD modeling of one patient's nose pre- and postsurgery showed significant improvement in postsurgical ortho- and retronasal airflow and odorant delivery rate to olfactory neuroepithelium (> 1000 times), which correlated well with olfactory recovery.

CONCLUSION

This study has introduced a novel technique (CFD) to calculate nasal airflow dynamics and its effects on olfaction, nasal obstruction, and sinus disease. In the future, such techniques may provide a quantitative evaluation of surgical outcome and an important preoperative guide to optimize nasal airflow and odorant delivery.

Glutamate concentration in whole saliva and taste responses to monosodium glutamate in humans

It is universally accepted that saliva plays an important role in taste sensations. However, interactions between constituents of whole saliva and the five basic taste modalities are still poorly understood. The aim of the present study was to evaluate possible relationship between endogenous glutamate (Glu) levels in whole saliva and taste responses to a prototypic umami substance, monosodium glutamate (MSG; 0.03-10.0%). Rated intensity and pleasantness of MSG taste was studied in healthy volunteers divided into a high glutamate (HG) in saliva (HG; n = 19) and low glutamate in saliva (LG; n = 18) group based on the median split level of salivary Glu. The HG and LG group did not differ in terms of electrogustometric thresholds, rated intensity of the MSG samples and pleasantness of distilled water and the lower MSG concentrations (0.03-1.0%). Perceived intensity of water taste was significantly (P < 0.05) higher in the LG subjects. The LG group rated the higher MSG concentrations (3.0-10.0%) as more unpleasant (P < 0.01). The difference remained significant after controlling for a between-group difference in age. The present results suggest that individual differences in salivary Glu levels may alter hedonic responses to suprathreshold MSG concentrations.

Olfactory and sensory attributes of the nose

The human nasal cavity contains multiple sensory and olfactory structures. The nasal mucosa with its complex innervation detects the danger substances in the air and stimulates the protective reflexes. Healthy olfactory mucosa allows for appreciation of pleasant aromas and food flavors. The olfactory nerve, in concert with the trigeminal nerve, serves as a main interpreter and modulator of chemosensory information. The anatomy of the olfactory neuroepithelium, which occupies only a small portion of the nasal mucosa, is generally well understood, while the presence and distribution of the sensory/tactile receptors in the mucosa of the nasal cavity is still a subject of controversy. The nasal vestibule, lined with skin, contains receptors that can sense noxious stimuli and air-flow. The sensitivity of the nasal mucosa to air-flow still needs further research. Understanding the distribution of the air-flow receptors could help to guide nasal surgery for obstruction.