Taste Disorders in Acute Stroke

Soluble Epoxide Hydrolase Inhibitor Ameliorates Olfactory Dysfunction, Modulates Microglia Polarization, and Attenuates Neuroinflammation after Ischemic Brain Injury

Olfactory bulb (OB) microglia activation and inflammation can lead to olfactory dysfunction, which often occurs after an ischemic stroke. Inhibition of soluble epoxide hydrolase (sEH) attenuates neuroinflammation in brain injuries by reducing the degradation of anti-inflammatory epoxyeicosatrienoic acids. However, whether sEH inhibitors can ameliorate olfactory dysfunction after an ischemic stroke remains unknown. Ischemic brain injury and olfactory dysfunction were induced by middle cerebral artery occlusion (MCAO) in Wistar Kyoto rats. The rats were administered 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), a selective sEH inhibitor. Olfactory function, cerebral infarct volume, and the degree of degeneration, microglial polarization and neuroinflammation in OB were evaluated. Following treatment with AUDA, rats subjected to MCAO displayed mild cerebral infarction and OB degeneration, as well as better olfactory performance. In OB, AUDA triggered a modulation of microglial polarization toward the M2 anti-inflammatory type, reduction in proinflammatory mediators, and enhancement of the antioxidant process. The effectiveness of AUDA in terms of anti-inflammatory, neuroprotection and anti-oxidative properties suggests that it may have clinical therapeutic implication for ischemic stroke related olfactory dysfunction.

Interventions for people with perceptual disorders after stroke: the PIONEER scoping review, Cochrane systematic review and priority setting project

Background

Stroke often affects recognition and interpretation of information from our senses, resulting in perceptual disorders. Evidence to inform treatment is unclear.

Objective

To determine the breadth and effectiveness of interventions for stroke-related perceptual disorders and identify priority research questions.

Methods

We undertook a scoping review and then Cochrane systematic review. Definitions, outcome prioritisation, data interpretation and research prioritisation were coproduced with people who had perceptual disorders post stroke and healthcare professionals. We systematically searched electronic databases (including MEDLINE, EMBASE, inception to August 2021) and grey literature. We included studies (any design) of interventions for people with hearing, smell, somatosensation, taste, touch or visual perception disorders following stroke. Abstracts and full texts were independently dual reviewed. Data were tabulated, synthesised narratively and mapped by availability, sense and interventions. Research quality was not evaluated. Our Cochrane review synthesised the randomised controlled trial data, evaluated risk of bias (including randomisation, blinding, reporting) and meta-analysed intervention comparisons (vs. controls or no treatment) using RevMan 5.4. We judged certainty of evidence using grading of recommendations, assessment, development and evaluation. Activities of daily living after treatment was our primary outcome. Extended activities of daily living, quality of life, mental health and psychological well-being perceptual functional and adverse event data were also extracted.

Results

We included 80 studies (n = 893): case studies (36/80) and randomised controlled trials (22/80). No stroke survivor or family stakeholder involvement was reported. Studies addressed visual (42.5%, 34/80), somatosensation (35%, 28/80), auditory (8.7%, 7/80) and tactile (7.5%, 6/80) perceptual disorders; some studies focused on 'mixed perceptual disorders' (6.2%, 5/80 such as taste-smell disorders). We identified 93 pharmacological, non-invasive brain stimulation or rehabilitation (restitution, substitution, compensation or mixed) interventions. Details were limited. Studies commonly measured perceptual (75%, 60/80), motor-sensorimotor (40%, 32/80) activities of daily living (22.5%, 18/80) or sensory function (15%, 12/80) outcomes.

Cochrane systematic review

We included 18 randomised controlled trials (n = 541) addressing tactile (3 randomised controlled trials; n = 70), somatosensory (7 randomised controlled trials; n = 196), visual (7 randomised controlled trials; n = 225) and mixed tactile-somatosensory (1 randomised controlled trial; n = 50) disorders. None addressed hearing, taste or smell disorders. One non-invasive brain stimulation, one compensation, 25 restitution and 4 mixed interventions were described. Risk of bias was low for random sequence generation (13/18), attrition (14/18) and outcome reporting (16/18). Perception was the most commonly measured outcome (11 randomised controlled trials); only 7 randomised controlled trials measured activities of daily living. Limited data provided insufficient evidence to determine the effectiveness of any intervention. Confidence in the evidence was low-very low. Our clinical (n = 4) and lived experience (n = 5) experts contributed throughout the project, coproducing a list of clinical implications and research priorities. Top research priorities included exploring the impact of, assessment of, and interventions for post-stroke perceptual disorders.

Limitations

Results are limited by the small number of studies identified and the small sample sizes, with a high proportion of single-participant studies. There was limited description of the perceptual disorders and intervention(s) evaluated. Few studies measured outcomes relating to functional impacts. There was limited investigation of hearing, smell, taste and touch perception disorders.

Conclusion

Evidence informing interventions for perceptual disorders after stroke is limited for all senses.

Future work

Further research, including high-quality randomised controlled trials, to inform clinical practice are required.

Study registration

This study is registered as PROSPERO CRD42019160270.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR128829) and is published in full in Health Technology Assessment; Vol. 28, No. 69. See the NIHR Funding and Awards Website for further award information.

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.

Increased sensitivity in detection of deficits following two commonly used animal models of stroke

Stroke is a leading cause of death and disability in the United States. Most strokes are ischemic, resulting in both cognitive and motor impairments. Animal models of ischemic stroke such as the distal middle cerebral artery occlusion (dMCAO) and photothrombotic stroke (PTS) procedures have become invaluable tools, with their own advantages and disadvantages. The dMCAO model is clinically relevant as it occludes the artery most affected in humans, but yields variability in the infarct location as well as the behavioral and cognitive phenotypes disrupted. The PTS model has the advantage of allowing for targeted location of infarct, but is less clinically relevant. The present study evaluates phenotype disruption over time in mice subjected to either dMCAO, PTS, or a sham surgery. Post-surgery, animals were tested over 28 days on standard motor tasks (grid walk, cylinder, tapered beam, and rotating beam), as well as a novel odor-based operant task; the 5:1 Odor Discrimination Task (ODT). Results demonstrate a significantly greater disturbance of motor control with PTS as compared with Sham and dMCAO. Disruption of the PTS group was detected up to 28 days post-stroke on the grid walk, and up to 7 days on the rotating and tapered beam tasks. PTS also led to significant short-term disruption of ODT performance (1-day post-surgery), exclusively in males, which appeared to be driven by motoric disruption of the lick response. Together, this data provides critical insights into the selection and optimization of animal models for ischemic stroke research. Notably, the PTS procedure was best suited for producing disruptions of motor behavior that can be detected with common behavioral assays and are relatively enduring, as is observed in human stroke.

Perceived Taste and Olfactory Dysfunctions and Subsequent Stroke Risk

Background

Taste and olfactory dysfunction are commonly associated with neurodegenerative diseases and cardiovascular risk factors, but their specific associations with stroke risk remain uncertain.

Objectives

The purpose of this paper was to explore whether perceived taste and olfactory dysfunctions were associated with stroke risk.

Methods

Included were 85,656 participants (mean age 51.0 ± 15.3 years) of the Kailuan study. Perceived olfactory and taste dysfunctions were assessed via a questionnaire at baseline (in 2014-2016). Incident stroke cases were confirmed by review of medical records. Cox proportional hazards models were used to investigate associations of perceived olfactory and taste dysfunctions with stroke risk, and mediation analysis was used to estimate the mediating effect of chronic disease statuses.

Results

We documented 2,198 incident stroke cases during a mean of 5.6 years of follow-up. Perceived taste dysfunction was associated with a doubled risk of developing total stroke (adjusted HR: 2.03; 95% CI: 1.36-3.04; P < 0.001) even with adjustment of lifestyle factors, biomarkers (ie, blood lipids, blood glucose, blood pressure, and uric acid), and other potential confounders. However, perceived olfactory dysfunction (adjusted HR: 1.22; 95% CI: 0.79-1.90; P = 0.34) was not significantly associated with a high risk of total stroke. Similar results of both perceived taste and olfactory dysfunctions were observed for ischemic stroke. Presence of chronic diseases, including hypertension, diabetes, chronic kidney disease, and overweight/obesity, mediated 4% to 5% of the association of perceived taste dysfunction with both total stroke and ischemic stroke.

Conclusions

In this large cohort study, perceived taste dysfunction was associated with a high risk of developing stroke.

The effect of post-COVID-19 on gustatory and olfactory function: A preliminary case-controlled study

AIMS

The aim of the study was to analyze objective and subjective olfactory/gustatory function in post-COVID-19 infection (PCI).

MATERIALS AND METHODS

Patients with past PCR-confirmed COVID-19 infection and persistent olfactory/gustatory complaints were investigated. Olfactory threshold and identification, gustatory detection, identification, and magnitude scaling were tested.

RESULTS

A total of 42 PCI subjects were compared to 41 age- and gender-matched controls with no COVID-19 history. All PCI tested had mild COVID-19 disease. Mean interval between COVID-19 confirmations to testing was 7.4 ± 3.1 months. PCI subjects complained of combined dysfunction in 85.7%, isolated olfactory or gustatory dysfunction in 7.1% each. Combined complaints were significantly higher in PCI (p < 0.001). Objective testing showed significantly higher prevalence of dysfunction in PCI versus controls for hyposmia (73.8%, 12.2%), anosmia (11.9%, 0%), odor identification (68.5%, 83.0%), hypogeusia (23% and 2.4%, respectively), and impaired magnitude scaling, (p < 0.05). All PCI subjects with hypogeusia had abnormal gustatory magnitude scaling.

CONCLUSIONS

While most PCI subjects complained of combined gustatory and olfactory dysfunction, objective testing showed in the majority an isolated single sense dysfunction, with a low level of agreement between subjective and objective findings. Abnormal objective results for all olfactory and gustatory functions tested may suggest a central rather than peripheral mechanism, although concomitant mechanisms cannot be excluded.

Clinical Neurology in Practice: The Tongue (part 2)

BACKGROUND

The tongue is an essential organ for the development of certain crucial functions such as swallowing and speech. The examination of the tongue can be very useful in neurology, as the various types of lingual alterations can lead to certain specific diagnoses, the tongue being a kind of 'mirror' of some neurological function.

REVIEW SUMMARY

To discuss the elements of clinical examination of the tongue in relation to neurological disorders. After reviewing the different superficial lesions of the tongue, we deal with various movement disorders of the tongue (fasciculations/myokimia, orolingual tremor, choreic movements of the tongue, dystonia of the tongue, lingual myoclonus, and psychogenic movements), disorders of taste and lingual sensitivity and lingual pain.

CONCLUSIONS

Examination of the tongue should not be limited to studying its motility and trophicity. It is equally important to check the sensory function and understand how to interpret abnormal movements involving the tongue. This study also aimed to demonstrate the importance of nonmotor tongue function in neurological practice.

The Revived Interest in Ageusia Research during the COVID-19 Pandemic: A Bibliometric Analysis

The evolution of ageusia research literature has yet to be investigated. This bibliometric study analyzed the entire ageusia research literature indexed in Web of Science, to reveal its growth and the most productive entities in terms of authors, institutions, countries, journals, and journal categories. In addition, this study aimed to identify medical conditions (and their treatments) that were frequently associated with ageusia. On 7 March 2022, the Web of Science Core Collection database was accessed with the following search query: TS = (ageusia OR "taste loss" OR "loss of taste" OR "loss of gustat*" OR "gustatory loss"). The search identified publications mentioning these terms in their title, abstract, or keywords. No additional filters were placed on publication year, language, etc. The basic publication and citation counts were extracted from the in-built functions of the database. The complete record of the publications was exported into VOSviewer, a bibliometric software for visualizations. The search yielded 1170 publications. The cumulative publication and citation counts of the ageusia research sharply increased in 2020. The most productive author was Professor Thomas Hummel from Technische Universität Dresden. Ageusia research had heavy contributions from the United States, Italy, the United Kingdom, Germany, and India. The top 5 most productive journals mainly belonged to the otorhinolaryngology and medicine categories. The medical conditions frequently investigated in ageusia research included COVID-19, cancers (head and neck, and advanced basal cell), Guillain-Barré syndrome, neurodegenerative diseases, diabetes, and Sjogren's syndrome. This study could act as a begvinner's guide for (1) clinicians who are not familiar with ageusia so that they might better understand which scenarios they need to be more aware of since ageusia could be a co-morbidity of a patient's underlying disease, and (2) for those who wish to search for relevant authors and journals for suitable publications related to the topic.

A Simple Taste Test for Clinical Assessment of Taste and Oral Somatosensory Function-The "Seven-iTT"

Taste dysfunctions may occur, for example, after viral infection, surgery, medications, or with age. In clinical practice, it is important to assess patients' taste function with rapidity and reliability. This study aimed to develop a test that assesses human gustatory sensitivity together with somatosensory functions of astringency and spiciness. A total of 154 healthy subjects and 51 patients with chemosensory dysfunction rated their gustatory sensitivity. They underwent a whole-mouth identification test of 12 filter-paper strips impregnated with low and high concentrations of sweet, sour, salty, bitter (sucrose, citric acid, NaCl, quinine), astringency (tannin), and spiciness (capsaicin). The percentage of correct identifications for high-concentrated sweet and sour, and for low-concentrated salty, bitter and spicy was lower in patients as compared with healthy participants. Interestingly, a lower identification in patients for both astringent concentrations was found. Based on the results, we proposed the Seven-iTT to assess chemo/somatosensory function, with a cut-off of 6 out of 7. The test score discriminated patients from healthy controls and showed gender differences among healthy controls. This quantitative test seems to be suitable for routine clinical assessment of gustatory and trigeminal function. It also provides new evidence on the mutual interaction between the two sensory systems.

Sensory Involvement in Amyotrophic Lateral Sclerosis

Although amyotrophic lateral sclerosis (ALS) is pre-eminently a motor disease, the existence of non-motor manifestations, including sensory involvement, has been described in the last few years. Although from a clinical perspective, sensory symptoms are overshadowed by their motor manifestations, this does not mean that their pathological significance is not relevant. In this review, we have made an extensive description of the involvement of sensory and autonomic systems described to date in ALS, from clinical, neurophysiological, neuroimaging, neuropathological, functional, and molecular perspectives.

[Transient changes in food preference in a patient with cerebellar infarction]

A 44-year-old woman was admitted to our hospital due to dizziness and ataxia of the trunk and right upper limb. Brain MRI revealed an acute infarct lesion in the right posterior inferior cerebellar artery territory. In addition to the cognitive deterioration observed in the subacute phase, a change was noted in her food preference-from light-tasting, low-caloric Japanese cuisine, sugarless coffee, and hot drinks to strong-tasting, high-caloric Western cuisine, sugar-rich coffee, and iced drinks. Single-photon emission computed tomography showed hypoperfusion in the bilateral frontal lobes and right cerebellum. These cognitive and food preference-related changes were gradually restored over six months after the onset. The reduced cerebral blood flow in the bilateral frontal lobes also restored along with the clinical improvement, with the maximal changes in the bilateral subcallosal areas. This case suggests that changes in food preference can occur as a symptom of cerebellar infarction, possibly by the mechanism similar to cerebellar cognitive affective syndrome.

[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.

Gustatory dysfunction in patients with olfactory dysfunction and the associated factors

BACKGROUND

Little is known about the occurrence of gustatory dysfunction (GD) in relation to different aetiologies of olfactory dysfunction (OD) as assessed by psychophysical chemosensory tests. The aim of this study was to analyse gustatory function in patients with OD and to investigate clinical factors associated with GD.

METHODS

A total of 742 individuals who underwent both olfactory and gustatory function tests at a tertiary medical centre from November 2019 to March 2021 were retrospectively enrolled. Olfactory and gustatory function were assessed by the YSK olfactory and gustatory function tests, respectively. Patients with OD were classified into four groups according to the aetiology: sinonasal disease, post-infection OD (PIOD), post-traumatic OD (PTOD), and others. Secondary outcomes included age, sex, smoking history, and alcohol history.

RESULTS

Among the 488 patients with OD, 93 (19.1%) showed GD and 395 (80.9%) had normal gustatory function. Only 25 (9.8%) among 254 individuals with normosmia showed GD. Analyses of these frequencies revealed a significant association between OD and GD. In addition, the taste score was significantly lower in patients with OD than individuals with normosmia. The frequency of GD was significantly higher in patients with PTOD (53.6%) than in those with OD of other aetiologies (sinonasal disease, 6.7%; PIOD, 13.0%; others, 24.4%). In the multivariate analysis, age ≥55 years and PTOD were associated with a high frequency of GD among patients with OD.

CONCLUSIONS

The current study show that GD is significantly associated with OD. In particular, GD is more common in patients with PTOD than in those with OD of other aetiologies.

Evaluating the GAD-2 to screen for post-stroke anxiety on an acute stroke unit

Post stroke anxiety is associated with reduced quality of life, worse rehabilitation outcomes and poor social functioning in stroke survivors. Despite its clinical relevance, there are a lack of screening tools to identify post-stroke anxiety. The Hospital Anxiety and Depression Scale (HADS-A) and Geriatric Anxiety Inventory (GAI) are the only self-report screening test for anxiety validated in stroke patients. However, both of these measures have limitations associated with their clinical utility, length of time to administer and cost to purchase. This study aimed to assess the classiciation accuracy of a freely available and shorter alternative, the Generalized Anxiety Disorder 2-item (GAD-2) for use in the acute stroke setting. This study used retrospective analysis of a sequential sample in a clinical database of mood and cognitive scores. Patients' scores on the GAD-2 and HADS-A were compared. The GAD-2 demonstrated strong convergent validity with the HADS-A and good specificity and sensitivity for clinical anxiety. In conclusion, the GAD-2 may be a useful screening assessment of post-stroke anxiety in the acute setting; however, it should be used with due consideration of the methodological limitations of this study.

Why Taste Is Pharmacology

The chapter presents an argument supporting the view that taste, defined as the receptor-mediated signaling of taste cells and consequent sensory events, is proper subject matter for the field of pharmacology. The argument develops through a consideration of how the field of pharmacology itself is to be defined. Though its application toward the discovery and development of therapeutics is of obvious value, pharmacology nevertheless is a basic science committed to examining biological phenomena controlled by the selective interactions between chemicals - regardless of their sources or uses - and receptors. The basic science of pharmacology is founded on the theory of receptor occupancy, detailed here in the context of taste. The discussion then will turn to consideration of the measurement of human taste and how well the results agree with the predictions of receptor theory.

Taste perception in children with different caries activity

PURPOSE

The aim of the study was to investigate whether caries-active and caries-free children differ in terms of their taste perception for sweet, sour, salty and bitter.

METHODS

The study group consisted of 100 children aged 5-10 years: 50 caries-free children and 50 children with at least four untreated carious lesions. Taste perception was analysed using two test systems. First, filter paper strips impregnated with four taste qualities (sweet, sour, salty, and bitter) at four defined intensities were used ("taste strips"). Then a tasting spray in suprathreshold concentration of the respective taste was applied. The children were asked to name the perceived taste. The parents answered a questionnaire about the children's dietary habits.

RESULTS

The children with high caries activity scored lower on average on the taste strips than the caries-free participants. For the taste sprays, the perception of the taste quality "bitter" was significantly worse in the children with caries than in caries-free children (Mann-Whitney U test p < 0.05).

CONCLUSION

The results of this study suggest that taste preferences in children are associated with increased susceptibility to tooth decay.

Therapeutic supplementation with zinc in the management of COVID-19-related diarrhea and ageusia/dysgeusia: mechanisms and clues for a personalized dosage regimen

Zinc supplementation is indicated for diarrhea and taste disorders, which are both features of COVID-19. Nevertheless, this strategy has not been tested for the treatment of these secondary complications in the current pandemic. Through an updated review, a practical appraisal was considered as a means of providing a medical nexus of therapeutic zinc regimens as an adjunct in the management of COVID-19–related diarrhea and ageusia/dysgeusia. While diarrhea and taste disorders are consequences of COVID-19, zinc supplementation is useful for non–COVID-19 patients with these clinical problems. The overwhelming evidence for supplementing with zinc in diarrhea and pneumonia is associated with the treatment of children, while for taste disorders the use of supplementing with zinc is more examined in adults. Whereas COVID-19 is more prevalent in adults, precautions should be exercised not to translate the zinc dosage used for children with diarrhea and taste disorders into the current pandemic. Therapeutic doses of zinc used for adults (∼50–150 mg/day of elemental zinc) could be included in the treatment strategies for COVID-19, but this proposal should be examined through randomized studies.

Excessive Expression of Microglia/Macrophage and Proinflammatory Mediators in Olfactory Bulb and Olfactory Dysfunction After Stroke

BACKGROUND/AIM

Olfactory dysfunction can be caused by stroke but the pathogenesis is still unclear. Previous studies have proved that olfactory dysfunction could be caused by microglia activation in the olfactory bulb and that middle cerebral artery occlusion (MCAO) may induce ipsilateral olfactory bulb microglia activation. This study aimed to explore the possible pathogenesis of ischemic stroke-induced olfactory dysfunction.

MATERIALS AND METHODS

We used a rat model of MCAO to simulate ischemic stroke. Olfactory function tests were performed using buried food test. The mRNA expression of olfactory marker protein (OMP), microglia/macrophage activation, and proinflammatory mediators were measured using reverse transcription-quantitative polymerase chain reaction.

RESULTS

Following MCAO, rats had poorer olfactory performance. In the olfactory bulb of the rats, the mRNA expression of OMP decreased and the mRNA expression of microglia/macrophage activation and proinflammatory mediators increased.

CONCLUSION

Ischemic stroke causes microglia/macrophage activation and promotes neuroinflammation in the olfactory bulb, causing olfactory dysfunction.

Taste changes in amyotrophic lateral sclerosis and effects on quality of life

The primary aim of the study is to evaluate possible taste changes in a cohort of amyotrophic lateral sclerosis patients (pALS) with dysphagia, focusing on eventual psychological and quality of life (QoL) implications. The second aim is to evaluate the changes of QoL following the use of a specific device that provides food flavour. Thirty-two ALS patients were recruited and divided into two groups: subjects feeding only through enteral tube (ET) and subjects still eating by oral way (OW). A specific set of questionnaires was selected and adapted to investigate possible changes of taste and the impact on psychological status and QoL. Moreover, a specific device that provides food flavours in a safety manner was applied to all patients. We found a perceived reduction of taste in ALS patients, in particular in the ET group. All patients showed a strong interest in the preservation of taste, and its loss negatively related to their QoL. The use of the flavour device improved the perceived QoL showing no side effects, even in the ET group. For the first time, our study revealed changes in taste perception in a cohort of ALS patients and the negative consequences that these changes have on psychological status and QoL. Furthermore, the positive effects of the device used to provide flavours suggest a possible rehabilitative effect, which should be better evaluated and confirmed in further studies.

Assessment of taste functions in allergic rhinitis patients undergoing allergen-specific immunotherapy

BACKGROUND

We evaluated taste functions of patients with perennial allergic rhinitis (AR) before and after allergen-specific immunotherapy (AIT).

METHODS

The study was designed as a prospective clinical study in our tertiary care hospital. Patients (n = 21) who were diagnosed with perennial AR on the basis of physical examination, skin prick test of at least 3* for HDM allergen and treated with AIT were enrolled in this study. A control group (n = 21) was selected from patients who were given intranasal steroids (INS) for perennial AR. Both groups had self-reported hyposmia and subjective loss of the sense of taste before treatment. Taste strips (Burghart, Wedel, Germany) were used for the taste identification scores before and after 6 months treatment.

RESULTS

A total of 42 subjects were included, with a mean age of 24.1 ± 7.9 years (range 15-43 years). Overall, the AIT group showed more of an improvement of taste function, observed in the total average test scores, compared to the INS group (p < 0.05), but no change was detected between the groups before treatment. No difference was found for the bitter taste scores between the study groups (p = 0.053).

CONCLUSION

Subcutaneous allergen immunotherapy resulted in more of an improvement in taste function than intranasal steroids. Further studies are needed.

Bilateral Ageusia and Tongue Anesthesia Following Unilateral Brainstem Infarct: A Case Report with a Brief Review of the Literature

We present the case of a 63-year-old male patient who suffered bilateral ageusia following a unilateral left-sided mesencephalon infarct. To the best of our knowledge, this is the first description of a mesencephalon lesion leading to ageusia. We discuss the literature on this rare but important symptom following a stroke.

Chemosensory function before and after multimodal treatment in chronic rhinosinusitis patients

OBJECTIVES/HYPOTHESIS

Olfactory dysfunction is common among the general population, with chronic rhinosinusitis (CRS) as one of the leading causes. Patients affected by CRS often report changes in taste sensations; however, quantitative measurements have not been performed to date. Therefore, the present study aimed to investigate gustatory and olfactory function in CRS patients prior to and after multimodal treatment.

STUDY DESIGN

Prospective cohort study.

METHODS

Twenty-one patients suffering from CRS with nasal polyps (14 male, seven female) with a mean age of 48 ± 15 years were included in the study. Chemosensory function was assessed prior to and approximately 190 days after multimodal treatment, which included endoscopic sinus surgery, oral antibiotics for 5 days, oral steroids for 12 days, and at least 6 weeks of topical nasal steroids. Olfactory function was tested with the Sniffin' Sticks test battery, whereas gustatory function was measured with taste strips. A clinically relevant change in olfactory function was defined as a change of ≥5 points in the threshold, discrimination, and identification scores.

RESULTS

Compared to normative data, patients baseline gustatory and olfactory function was impaired. After multimodal treatment, improvements were seen in olfactory function for eight patients (42%), remained stable in 10 patients (53%), and deteriorated in one patient (5%). Taste function remained unchanged following sinus surgery.

CONCLUSIONS

Patients suffering from CRS with polyps exhibit olfactory and taste dysfunctions. Multimodal treatment leads to an improvement in olfactory, but not gustatory functionality.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:E86-E90, 2018.

Sour taste increases swallowing and prolongs hemodynamic responses in the cortical swallowing network

Sour stimuli have been shown to upregulate swallowing in patients and in healthy volunteers. However, such changes may be dependent on taste-induced increases in salivary flow. Other mechanisms include genetic taster status (Bartoshuk LM, Duffy VB, Green BG, Hoffman HJ, Ko CW, Lucchina LA, Weiffenbach JM. Physiol Behav 82: 109-114, 2004) and differences between sour and other tastes. We investigated the effects of taste on swallowing frequency and cortical activation in the swallowing network and whether taster status affected responses. Three-milliliter boluses of sour, sour with slow infusion, sweet, water, and water with infusion were compared on swallowing frequency and hemodynamic responses. The sour conditions increased swallowing frequency, whereas sweet and water did not. Changes in cortical oxygenated hemoglobin (hemodynamic responses) measured by functional near-infrared spectroscopy were averaged over 30 trials for each condition per participant in the right and left motor cortex, S1 and supplementary motor area for 30 s following bolus onset. Motion artifact in the hemodynamic response occurred 0-2 s after bolus onset, when the majority of swallows occurred. The peak hemodynamic response 2-7 s after bolus onset did not differ by taste, hemisphere, or cortical location. The mean hemodynamic response 17-22 s after bolus onset was highest in the motor regions of both hemispheres, and greater in the sour and infusion condition than in the water condition. Genetic taster status did not alter changes in swallowing frequency or hemodynamic response. As sour taste significantly increased swallowing and cortical activation equally with and without slow infusion, increases in the cortical swallowing were due to sour taste.

Using Animal Models to Determine the Role of Gustatory Neural Input in the Control of Ingestive Behavior and the Maintenance of Body Weight

INTRODUCTION

Decades of research have suggested that nutritional intake contributes to the development of human disease, mainly by influencing the development of obesity and obesity-related conditions. A relatively large body of research indicates that functional variation in human taste perception can influence nutritional intake as well as body mass accumulation. However, there are a considerable number of studies that suggest that no link between these variables actually exists. These discrepancies in the literature likely result from the confounding influence of a variety of other, uncontrolled, factors that can influence ingestive behavior.

STRATEGY

In this review, the use of controlled animal experimentation to alleviate at least some of these issues related to the lack of control of experimental variables is discussed. Specific examples of the use of some of these techniques are examined.

DISCUSSION AND CONCLUSIONS

The review will close with some specific suggestions aimed at strengthening the link between gustatory neural input and its putative influence on ingestive behaviors and the maintenance of body weight.

Disorders of "taste cognition" are associated with insular involvement in patients with Alzheimer's disease and vascular dementia: "memory of food is impaired in dementia and responsible for poor diet"

BACKGROUND

In dementia patients, dietary intake problems may occur despite the absence of swallowing problems. We investigated cognitive functions on food and taste in Alzheimer's disease (AD) and vascular dementia (VaD) patients.

METHODS

Participants included 15 healthy controls (HC), 30 AD and 20 VaD patients. Food Cognition Test: Replicas of three popular foods in Japan with no odors were presented visually to each participant, with the instruction to respond with the name of each food. Replicas of food materials were subsequently presented to ask whether they were included in these foods. Taste Cognition Test: Replicas of 12 kinds of foods were presented to describe their expected tastes.

RESULTS

The AD/VaD groups exhibited significantly lower scores on Food/Taste Cognition Tests compared with the HC group. These scores correlated inversely with Mini-Mental State Examination (MMSE) scores in the AD group. Decreased dietary intake was observed in 12 of the 50 patients; 8 of the 12 exhibited decreased Taste Cognition Test scores, higher than that of the normal-intake patients. There was no difference in the filter paper taste disc test between HC/AD/VaD groups. To test the hypothesis that the insula is associated with taste cognition, two MMSE-matched AD subgroups (n = 10 vs. 10) underwent positron emission tomography. Glucose metabolism in the right insula was lower in the low taste cognition subgroup. The VaD patients with insular lesions exhibited impaired Taste Cognition Test findings.

CONCLUSIONS

It is important to consider the cognitive aspect of dietary intake when we care for dementia patients.

Aroma and taste perceptions with Alzheimer disease and stroke

Chemosensory disorders of smell or taste in humans have been attributed to various physiological and environmental factors including aging and disease conditions. Aroma and taste greatly condition our food preference, selection and, consumption; the decreased appetite in patients with known neurodegenerative diseases may lead to dietary restrictions that could negatively impact nutritional and health status. The decline in olfactory and gustatory systems in patients with Alzheimer disease and various types of stroke are described.

Zinc deficiency and taste perception in the elderly

Taste, one of the major senses in humans, is the ability to detect the flavor of substances such as food, certain minerals, and poisons. Taste distortions in human beings have been attributed to various physiological and environmental factors including aging and disease conditions. Given the fact that taste is one of the most important factors in food preference, selection, and consumption, the decreased appetite in the elderly, probably due to disease conditions, may lead to dietary restrictions that could negatively impact nutritional and health status. The role of zinc on taste distortion in the elderly population and taste impairment are described. Although several studies demonstrate the associative nature of taste degeneration with age, additional investigations are required to clarify the mechanisms by which taste perception is altered with age.

Effect of bolus taste on the esophageal transit of patients with stroke

Stroke is a frequent cause of oropharyngeal dysphagia but may also cause alterations in esophageal motility. The aim of this investigation was to evaluate the effect of bolus taste on the esophageal transit of patients with stroke and controls. Esophageal transit and clearance were evaluated by scintigraphy in 36 patients in the chronic phase of stroke (44-82 years, mean: 63 years) and in 30 controls (33-85 years, mean: 59 years). The patients had a stroke 1-84 months (median: 5.5 months) before the evaluation of esophageal transit. Eight had dysphagia. Each subject swallowed in random order and in the sitting position 5 mL of liquid boluses with bitter (pH=6.0), sour (pH=3.0), sweet (pH=6.9), and neutral (pH=6.8) taste. Transit and clearance duration and the amount of residues were measured in the proximal, middle, and distal esophageal body. There was no difference between patients and controls in esophageal transit or clearance duration. In the distal esophagus, the transit and clearance durations were longer with the sour bolus than with the other boluses in both patients and controls. The amount of residues in the esophageal body was greater in patients than in controls after swallows of the neutral bolus. In control subjects, after swallows of a sour bolus, there was an increase in the amount of residues in the middle and distal esophagus compared with the other boluses. In conclusion, a sour bolus with low pH causes a longer transit and clearance duration in the distal esophageal body. There was no effect of bolus taste or pH on the esophageal transit of patients in the chronic phase of stroke compared with normal volunteers. The longer transit and clearance duration in the distal esophageal body with the sour bolus appears to be a consequence of the low pH of the bolus.

Altered taste and stroke: a case report and literature review

Patients with altered taste perception following stroke are at risk for malnutrition and associated complications that may impede recovery and adversely affect quality of life. Such deficits often induce and exacerbate depressive symptomatology, which can further hamper recovery. It is important for clinicians and rehabilitation specialists to monitor stroke patients for altered taste perception so that this issue can be addressed. The authors present the case of a patient who experienced an isolated ischemic infarct affecting a primary cortical taste area. This case is unusual in that the isolated injury allowed the patient to remain relatively intact cognitively and functionally, and thus able to accurately describe her taste-related deficits. The case is further used to describe the relevant neurological taste pathways and review potential taste-related therapies.

Altered taste and stroke: a case report and literature review

Patients with altered taste perception following stroke are at risk for malnutrition and associated complications that may impede recovery and adversely affect quality of life. Such deficits often induce and exacerbate depressive symptomatology, which can further hamper recovery. It is important for clinicians and rehabilitation specialists to monitor stroke patients for altered taste perception so that this issue can be addressed. The authors present the case of a patient who experienced an isolated ischemic infarct affecting a primary cortical taste area. This case is unusual in that the isolated injury allowed the patient to remain relatively intact cognitively and functionally, and thus able to accurately describe her taste-related deficits. The case is further used to describe the relevant neurological taste pathways and review potential taste-related therapies.

[Bilateral ageusia caused by right thalamic infarction]

A 58-year-old man noticed left hemiparesis at 01:00 pm on a particular day in March 2006. Because his symptoms developed gradually, he was referred to the emergency room of our hospital at 05:00 pm and was admitted with the diagnosis of cerebral infarction. While he presented slight left hemiparesis involving the face, impairment of sensation was not apparent. Diffusion-weighted magnetic resonance imaging of the head showed a high-intensity area in the ventromedial area in the right thalamus. The patient was treated with anticoagulant and edaravone, and his symptoms resolved on hospital day 3. When he began eating, he noticed that he was unable to distinguish tastes. On day 5, we performed taste examination using a commercial kit. The taste sensation on both sides of his tongue was severely affected, while the touch sensations in the mouth and olfaction were preserved. His symptoms improved spontaneously and resolved on hospital day 15. This is the second case report of bilateral ageusia caused by right thalamic infarction. Our study indicates the importance of the right thalamus in taste sensation involving both sides of the tongue.

Olfactory function in patients with ischemic stroke: a pilot study

The aim of this pilot study was to investigate olfactory function in unselected, cooperative patients with ischemic stroke and to gain information about olfactory perception in patients with distinct stroke localizations. Three ischemic stroke patients underwent olfactory testing using the Sniffin' Sticks test and olfactory event-related potentials recording. All stroke patients were found to be normosmic or only slightly hyposmic when using a psychophysical testing device with age-adjusted norms. No responses or longer latencies on the affected side were found, however, when recording evoked potentials. This seems to argue for the idea that on the affected side it is often possible to document the objective lesion although the subjective perception of the patient appears normal.

Percepção de sabores em pacientes com acidente vascular encefálico

OBJETIVO: avaliar a percepção dos sabores amargo, azedo, doce e neutro. MÉTODO: foram estudados 36 pacientes com Acidente Vascular Encefálico (AVE) (5 hemorrágicos e 31 isquêmicos) e 30 sujeitos controles. Foi realizada avaliação fonoaudiológica estrutural e funcional incluindo postura, vedamento labial, presença de resíduos, tosse, engasgo, e ausculta cervical. Cada sujeito deglutiu em sequência aleatória 5 mL de líquido com os 4 sabores [chá de boldo (amargo), suco de limão diluído (azedo), sacarose diluída (doce) e água (neutro)] na temperatura ambiente. Entre as deglutições os participantes eram questionados sobre a dificuldade em deglutir e qual o sabor do líquido daquela deglutição. RESULTADOS: entre os pacientes houve maior freqüência de erros na identificação dos sabores amargo (controles: 16,7%, AVE: 47,3%, p=0,01) e azedo (controles: 6,7%, AVE: 27,8%, p=0,05), sem diferenças para o sabores neutro (controles: 10,0%, AVE: 16,7%, p=0,50) e doce (controles: 13,3%, AVE: 16,7%, p=0,80). Os pacientes com AVE tiveram maior dificuldade para deglutir os líquidos do que os controles (p<0,04). CONCLUSÃO: houve maior dificuldade na percepção dos sabores amargo e azedo no grupo com AVE do que nos controles.

Developing workable research methods: lessons from a pilot study with vulnerable participants and complex assessments

Following acute stroke, deterioration in nutritional status and weight loss is common; few studies have investigated this, perhaps due to difficulties with recruitment and completion of complex assessments with stroke patients. This study reports the feasibility of a study protocol to determine predictors of nutritional intake in stroke patients. The aim of the study was to test the feasibility of a protocol to measure taste and smell function, and explore links with dietary intake following stroke. Patients were recruited from one Acute Stroke Unit in 2007/8. Data were collected at three time-points and entailed standardised validated assessments of taste and smell function, diet, appetite and mood state. Recruitment of this vulnerable population to a demanding assessment schedule was challenging. Of a cohort of 166 admissions, six were recruited and complete data collected from four participants. Slow recruitment was largely due to exacting inclusion criteria and rapid hospital discharge. Those who completed all assessments reported the schedule as tolerable and acceptable. This study illustrated the difficulties of recruiting this vulnerable population. Identification of reasons for slow recruitment facilitated development of measures to address them. It was possible to format a complex and lengthy assessment schedule to be acceptable to vulnerable participants.

Fluctuating gustatory disturbance and ophthalmodynia heralding the onset of a paramedian pontine infarction

Lasting taste disturbance has been previously reported as a consequence of brainstem infarction, but there are no previous reports of transient gustatory sensations preceding the onset of stroke. Ophthalmodynia, presenting as "salt-and-pepper" eye pain, has been reported rarely. We present a 58-year-old right-handed woman who had fluctuating ophthalmodynia and taste disturbance immediately preceding a left paramedian pontine infarction. We discuss the neuroanatomical basis of taste in reference to this presentation.

Transient cerebral ischemia induces active astrocytosis without distinct neuronal death in the gerbil main olfactory bulb: a long-term analysis

In the present study, we examined ischemia-induced neuronal and glial changes in the gerbil MOB at various time points during 60 days after 5 min of transient cerebral ischemia. The number of neuronal neuclei-immunoreactive neurons was not changed after ischemia/reperfusion (I/R). Myelin basic protein immunoreaction was well preserved after I/R. Five days after I/R, reactive form of GFAP-immunoreactive astrocytes began to increase in the external plexiform layer and granule cell layer: These reactive astrocytes peaked 10 days after I/R, thereafter, they decreased with time after I/R. Iba-1-immunoreactive microglia were ubiquitously distributed in all layers of the MOB. After I/R, significant changes in their morphology and immunoreactivity were not detected. The results of western blot analyses for GFAP, Iba-1 and MBP were similar to the immunohistochemical data. In addition, 8-hydroxy-2'-deoxyguanosine (a marker for DNA damage) immunoreactivity and SOD1, an antioxidant, protein levels were not changed in the ischemic MOB. These results indicate that neurons in the MOB are resistant to ischemic insult, showing that astrocytes are activated late in the ischemic MOB.

Superior cerebellar artery infarction in endovascular treatment for tentorial dural arteriovenous fistulas

BACKGROUND

Superior cerebellar artery (SCA) syndrome shows ipsilateral cerebellar ataxia and Horner's syndrome, contralateral superficial sensory disturbance, as well as nystagmus toward the impaired side, vertigo, and nausea. Occasionally, unilateral lesions may produce bilateral hypogeusia and contralateral hypoacusia.

OBJECTIVE

To report 2 patients with unilateral lower midbrain ischemic lesions of the inferior colliculus level caused by transarterial embolization for tentorial dural arteriovenous fistulas (TDAVFs).

METHODS

Hospital records for 21 patients with TDAVFs mainly treated by endovascular techniques between 2005 and 2008 were reviewed. Two patients with MRI evidence of unilateral SCA territory infarction were investigated.

RESULTS

Of 21 patients, 2 treated transarterially with Onyx-18 (a nonahesive liquid embolic agent) developed infarctions in the territory of SCA. One patient had lateral SCA infarction characterized by ipsilateral gait ataxia, contralateral hemihypoesthesia, with additional ipsilateral ocular motor palsy and bilateral gustatory loss. And the other patient had medial SCA infarction characterized by ipsilateral ataxia contralateral hemihypoesthesia with additional contralateral hypoacusia.

CONCLUSION

SCA infarction can be caused by transarterial injection of Onyx-18 via SCA or the posterior cerebral artery (PCA) for TDAVFs and additionally presented with gustatory loss and deafness, which is generally not a feature of the SCA syndrome.

Chemosensory interaction: acquired olfactory impairment is associated with decreased taste function

Olfaction, taste and trigeminal function are three distinct modalities. However, in daily life they are often activated concomitantly. In health and disease, it has been shown that in two of these senses, the trigeminal and olfactory senses, modification of one sense leads to changes in the other sense and vice versa. The objective of the study was to investigate whether and (if so) how, the third modality, taste, is influenced by olfactory impairment. We tested 210 subjects with normal (n = 107) or impaired (n = 103) olfactory function for their taste identification capacities. Validated tests were used for olfactory and gustatory testing (Sniffin' Sticks, Taste Strips). In an additional experiment, healthy volunteers underwent reversible olfactory cleft obstruction to investigate short-time changes of gustatory function after olfactory alteration. Mean gustatory identification (taste strip score) for the subjects with impaired olfaction was 19.4 +/- 0.6 points and 22.9 +/- 0.5 points for those with normal olfactory function (t = 4.6, p < 0.001). The frequencies of both, smell and taste impairments interacted significantly (Chi(2), F = 16.4, p < 0.001), and olfactory and gustatory function correlated (r (210) = 0.30, p < 0.001). Neither age nor olfactory impairment cause effects interfered with this olfactory-gustatory interaction. In contrast, after short-lasting induced olfactory decrease, gustatory function remained unchanged. The present study suggests that longstanding impaired olfactory function is associated with decreased gustatory function. These findings seem to extend previously described mutual chemosensory interactions also to smell and taste. It further raises the question whether chemical senses in general decrease mutually after acquired damage.

Olfactory dysfunction after subarachnoid hemorrhage caused by ruptured aneurysms of the anterior communicating artery

Object

Olfactory dysfunction has an important impact on quality of life. In patients with subarachnoid hemorrhage (SAH), anosmia has mainly been reported after surgery for aneurysms of the anterior communicating artery (ACoA). The authors studied whether and how frequently patients with ACoA aneurysms present with smell identification deficits in 2 treatment groups (endovascular and surgical treatment).

Methods

A prospective study was conducted of patients with SAH caused by ruptured ACoAs and who had a Glasgow Outcome Scale score of 1 or 2, in comparison with a control group matched by age and sex. Olfactory function was assessed using the University of Pennsylvania Smell Identification Test (UPSIT).

Results

A total of 39 patients were enrolled. A marked olfactory impairment was observed in patients with ruptured ACoAs compared with the control group (p < 0.001). Seventeen patients with ruptured ACoAs (44%) compared with 1 patient in the control group (3%) showed a smell identification deficit according to performance on the UPSIT (p < 0.001). Both groups that underwent treatment presented with olfactory impairment. Ten (59%) of 17 patients who underwent aneurysmal clip placement versus 6 (28.5%) of 21 patients who underwent coil embolization scored below the 25th percentile on the UPSIT, and surgical patients also performed worse than endovascular patients (p = 0.048). The authors observed a worse performance on the olfactory test in patients subjected to endovascular coil embolization when cerebral vasospasm (p = 0.037) or frontal cerebral lesions (p = 0.009) were present. This difference was not observed in patients who underwent surgery.

Conclusions

Olfactory disorders after SAH caused by rupture of the ACoA are very frequent and were present in both treatment groups. Cerebral vasospasm and frontal lobe lesions are related to worse performance on an olfactory test in patients undergoing endovascular coil embolization.

Smell and taste disorders in polyneuropathy: a prospective study of chemosensory disorders

OBJECTIVE

The aim of the study was to assess the occurrence and the frequency of chemosensory dysfunction in patients with polyneuropathy (PNP).

METHODS

We performed a prospective observational study. Olfactory function was assessed using the standardized 'Sniffin' Sticks' test to measure odor threshold for phenyl ethyl alcohol, odor discrimination, and odor identification. Gustatory function was assessed using the standardized 'taste strips' test. In addition, we assessed etiology, neurophysiology, and severity of the PNP, and the patients' comorbidities and medication.

RESULTS

A total of 53 consecutive patients were enrolled (15 women, 38 men; mean age 61 years); 27 of them (51%) exhibited olfactory dysfunction and 23 of them (43%) gustatory dysfunction. Patients with diabetic PNP had significantly lower taste scores than patients with inflammatory, genetic, or idiopathic PNP. In addition, odor identification was negatively correlated with PNP severity.

CONCLUSION

The applied bedside tests are useful to detect chemosensory dysfunction in patients with PNP. Chemosensory dysfunction is quite frequent in these patients.