Determinants of Single and Multiple Sensory Impairments in an Urban Population

Taste disturbance following cochlear implantation: a systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis aimed to estimate the rate of taste disturbance following cochlear implantation.

METHODS

The review was designed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies psychophysically measured taste. DerSimonian and Laird random-effects models were used. An overall mean from studies reporting a single mean of taste strip performance was calculated using inverse variance method for pooling.

RESULTS

Of 380 studies identified, 9 were included across which 55 cases of postoperative taste disturbance were reported in 498 patients. Taste was tested at variable timepoints, from <1 week to ≥6 months postoperatively. The overall rate of postoperative taste disturbance was 13.5% (95% CI, 7.6-20.7%) with high heterogeneity between studies (I2 = 62%).

DISCUSSION

13.5% might indicate a higher prevalence of taste disturbance following cochlear implantation compared to the general population. However, the confidence we can assign to our calculated rate is limited by significant heterogeneity and potential publication bias. Studies reporting mean taste strip scores generally found reduced taste function on the side of the tongue ipsilateral to implantation, but this reduction wasn't statistically significant.

CONCLUSION

Further research, employing more robust and standardised methodologies, is necessary to accurately ascertain the rate and nature of taste disturbance following cochlear implantation.

Self-reported dual sensory impairment and related factors: a European population-based cross-sectional survey

BACKGROUND

Data on population-based self-reported dual vision and hearing impairment are sparse in Europe. We aimed to investigate self-reported dual sensory impairment (DSI) in European population.

METHODS

A standardised questionnaire was used to collect medical and socio-economic data among individuals aged 15 years or more in 29 European countries. Individuals living in collective households or in institutions were excluded from the survey.

RESULTS

Among 296 677 individuals, the survey included 153 866 respondents aged 50 years old or more. The crude prevalence of DSI was of 7.54% (7.36-7.72). Among individuals aged 60 or more, 9.23% of men and 10.94% of women had DSI. Eastern and southern countries had a higher prevalence of DSI. Multivariable analyses showed that social isolation and poor self-rated health status were associated with DSI with ORs of 2.01 (1.77-2.29) and 2.33 (2.15-2.52), while higher income was associated with lower risk of DSI (OR of 0.83 (0.78-0.89). Considering country-level socioeconomic factors, Human Development Index explained almost 38% of the variance of age-adjusted prevalence of DSI.

CONCLUSION

There are important differences in terms of prevalence of DSI in Europe, depending on socioeconomic and medical factors. Prevention of DSI does represent an important challenge for maintaining quality of life in elderly population.

International consensus statement on allergy and rhinology: Olfaction

BACKGROUND

The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).

METHODS

Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.

RESULTS

The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.

CONCLUSION

This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Sensory Capacities and Eating Behavior: Intriguing Results from a Large Cohort of Italian Individuals

Eating behavior (EB) is a complex system influenced by many factors, but an undisputed role is played by the senses. In this work, we examined the effect of the sensory capacities on EB in 1152 Italian adult individuals. After administering a questionnaire on EB and assessing sensory performance through standard audiometric, olfactory, and taste tests, the prevalence of reduced sensory capacities (RSCs) and the correlation with selected risk factors were calculated. Regression models, structural equation modelling, and conditional recursive partitioning were used to investigate the relationship between variables. Around 70% of the subjects show reduced capacities in at least one sense, with taste being the most prevalent (55.21%). Male sex, aging, and low educational level are risk factors for RSCs. The increased number of senses with reduced capacities is a predictor of diminished food adventurousness and lower liking for vegetables, fish, and alcoholic beverages, while reduced capacities (RCs) in taste is a predictor of lower liking for alcoholic beverages and sweets. Overall, in addition to providing an overall picture of RSCs in Italian samples, our study reveals the association of RSCs with EB variables. This finding could have a relevant role in influencing individuals’ dietary habits and, therefore, health status.

Taste-strip gustometry in cochlear implanted patients

OBJECTIVE

Investigation of the gustatory function in a large cohort of cochlear implanted patients using lateralized taste-strip tests.

PATIENTS AND METHODS

One hundred and seven unilaterally or bilaterally profoundly hearing impaired or deaf patients who received cochlear implants (n = 113) were included in this study. Data on gustometry, subjective gustatory dysfunction, and the detailed surgical procedure were acquired retrospectively. Gustatory function, assessed using lateralized taste-strip tests, was performed the day before, 3 days after cochlear implantation, and on the day of the initial CI adjustment (39 days ±7.3 SD).

RESULTS

Averaged taste-strip scores of the cohort declined significantly from preoperatively 12.3 [11.8; 12.7] (mean [95% confidence intervals]) to 10.5 [9.7; 11.2] on the implanted side about 6 weeks after surgery. Patients with intraoperatively exposed and rerouted, or a severed, chorda tympani nerve (CTN) showed significantly reduced unilateral postoperative scores (10.1 [8.8; 11.4] and 9.3 [8.1; 10.5], respectively), when compared to not exposing or to leaving a bony layer over the CTN. Total taste-strip test scores showed a significant decline 6 weeks postoperatively in CI-patients expressing a subjective gustatory dysfunction (from 23.6 [21.4; 25.8] to 17.5 [14.2; 20.8]), as opposed to patients with a documented subjectively normal taste.

CONCLUSION

We consider postoperative gustatory dysfunction as a relevant side effect post cochlear implantation, at least within the first month. Taste-strip based gustometry is a suitable diagnostic tool to assess taste function in CI patients and is recommended to be performed routinely.

LEVEL OF EVIDENCE

3, retrospective, nonrandomized follow-up study.

Association between social determinants of health and olfactory function: a scoping review

BACKGROUND

Social determinants of health (SDoH) include the socioeconomic, demographic, and social conditions that influence differences in health status among individuals and groups. The impact of these conditions on olfactory function remains poorly understood. In this scoping review, we systematically review the available literature to synthesize the association between SDoH and olfactory function.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Review (PRISMA-ScR) guidelines, we performed systematic search queries in PubMed, Embase, and Ovid databases and categorized articles according to themes that emerged regarding SDoH. The primary outcomes included self-reported and objective measurements of smell.

RESULTS

We identified 722 unique references that underwent title and abstract review by two independent reviewers, with 70 articles undergoing full-text review and 57 relevant for data extraction. Six themes emerged in our review, under which we categorized the studies and synthesized respective associations with olfactory function. These include studies exploring socioeconomic status (n = 19, 33%), education status (n = 27, 47%), occupational exposures (n = 26, 46%), racial/ethnic disparities (n = 12, 21%), and lifestyle/behavioral factors (n = 33, 58%).

CONCLUSIONS

Within the context of this scoping review, olfactory dysfunction is significantly more prevalent in patients with lower socioeconomic status, exposure to environmental and occupational toxins, and of minority race/ethnicity, whereas the associations between olfactory dysfunction and education level and lifestyle factors such as smoking and drinking seem to be much more elusive. This review highlights the importance of accounting for SDoH in observational studies examining olfactory outcomes. Given the increased awareness of olfactory loss, special consideration should be given to understanding olfactory dysfunction in the context of these factors.

Differences in taste and smell perception between type 2 diabetes mellitus patients and healthy controls

BACKGROUND AND AIMS

The senses of taste and smell are essential determinants of food choice, which in turn may contribute to the development of chronic diseases, including diabetes. Although past studies have evaluated the relationship between type 2 diabetes mellitus (DM2) and senses disorders, this relationship remains controversial. In this study, we evaluated taste and smell perception in DM2 patients and healthy controls (HC). Moreover, we analyzed the association of chemosensory impairments with anthropometric and clinical outcomes (e.g. Body Mass Index (BMI), Fasting blood glucose (FBG), drugs, cardiovascular diseases (CVD), and hypertension) in DM2 patients.

METHODS AND RESULTS

The study included 94 DM2 patients and 244 HC. Taste recognition for 6-n-propylthiouracil (PROP), quinine, citric acid, sucrose, and sodium chloride (NaCl) compounds was assessed using a filter paper method, while smell recognition of 12 odorants was performed using a Sniffin' sticks test. We found that a higher percentage of DM2 patients showed identification impairment in salt taste (22% vs. 5%, p-value<0.0009) and smell recognition (55% vs. 27%, p-value = 0.03) compared to HC. We also observed that 65% of hypertensive DM2 subjects presented smell identification impairment compared to 18% of non-hypertensive patients (p-value = 0.019). Finally, patients with impairments in both taste and smell showed elevated FBG compared to patients without impairment (149.6 vs.124.3 mg/dL, p-value = 0.04).

CONCLUSION

The prevalence of taste and smell identification impairments was higher in DM2 patients compared to HC, and a possible relationship with glycemic levels emerged.

Clinical assessment of olfactory function

Approximately 5% of the general population is affected by functional anosmia with approximately additional 15% exhibiting decreased olfactory function. Many of these individuals ask for help. Because the subjective rating of olfactory function is biased, assessment of olfactory function is important. Olfactory measurements are needed for patient counseling and the tracking of changes in the sense of smell over time. The present review provides an overview of frequently used psychophysical tests for olfactory function, discusses differences between threshold and suprathreshold aspects of olfactory function, and gives examples on how to apply psychophysical tests.

Understanding ethnic inequalities in hearing health in the UK: a cross-sectional study of the link between language proficiency and performance on the Digit Triplet Test

INTRODUCTION

Research using the UK Biobank data has shown ethnic inequalities in hearing health; however, the hearing test used may exhibit a disadvantage for non-native language speakers.

OBJECTIVES

To validate the results of the UK Biobank hearing test (Digit Triplet Test, DTT) against self-reported measures of hearing in the dataset and create classifications of hearing health. To observe if language proficiency and migration age have the same effect on hearing health classification as on the DTT in isolation. Our hypothesis is that language proficiency acts differently on the DTT, demonstrating that the DTT is biased for non-native speakers of English.

DESIGN

Latent classes representing profiles of hearing health were identified from the available hearing measures. Factors associated with class membership were tested using multinomial logistic regression models. Ethnicity was defined as (1) White, native English-speaking, (2) ethnic minority, arrived in the UK aged <12 or (3) ethnic minority, arrived aged >12.

PARTICIPANTS

The UK Biobank participants with valid hearing test results and associated covariates (N=151 268).

OUTCOME MEASURES

DTT score, self-reported hearing difficulty, self-reported hearing difficulty in noise and hearing aid use.

RESULTS

Three classes of hearing health were found: 'normal', 'generally poor' and 'only subjectively poor'. In a model adjusting for known confounders of hearing loss, a poor or insufficient hearing test result was less likely for those with better language (OR 0.69, 95% CI 0.65 to 0.74) or numerical ability (OR 0.71, 95% CI 0.67 to 0.75) but more likely for those having migrated aged >12 (OR 3.85, 95% CI 3.64 to 4.07).

CONCLUSIONS

The DTT showed evidence of bias, having greater dependence on language ability and migration age than other hearing indicators. Designers of future surveys and hearing screening applications may wish to consider the limitations of speech-in-noise tests in evaluating hearing acuity for populations that include non-native speakers.

The Changing Landscape of Parkinson Epidemiologic Research

Despite recent successes in understanding the genetics of Parkinson’s disease (PD), the causes of late-onset sporadic PD remain elusive. Many of the epidemiologic findings on PD etiology have been challenged by alternative explanations such as reverse causation. This is mainly because PD often takes decades to develop before it can be diagnosed late in life. Convincing evidence shows that this prodromal stage of PD is characterized by various prodromal symptoms such as olfactory impairment and rapid-eye-movement sleep behavior disorder (RBD). As they likely reflect PD pathogenesis years, if not decades, before nigrostriatal involvement, research on these symptoms may represent an unprecedented opportunity to dissect the etiology of PD. Using PD prodromal symptoms as intermediate phenotypes, we may be able to identify factors that contribute to the development of these symptoms and factors that modify their progression to clinical PD. Further, this line of research will also enable examinations of novel etiological hypotheses of PD development such as the microbiome and prion hypotheses. In this article, the author used olfactory impairment and RBD as examples to illustrate the promises and challenges of epidemiologic research on prodromal symptoms to understand PD etiology.

The association between diabetes and olfactory impairment in adults: A systematic review and meta-analysis

Background

Evidence suggests that olfactory impairment (OI) may be a degenerative neurologic complication of diabetes; however, the association is not yet well established. The objective of this work was to systematically review existing literature on the association between diabetes and OI in adults, with meta‐analysis of evaluable studies.

Methods

A literature search encompassing 358 abstracts from the last 75 years in PubMed, EMBASE, and Cochrane was performed. English‐language articles investigating adults with diabetes and OI in comparison to control groups with original data and ≥7 subjects were included. The Newcastle‐Ottawa scale was applied for quality assessment. Two investigators independently reviewed all articles. For meta‐analysis, the odds ratio of OI in diabetes compared with control groups was calculated using the fixed effects model.

Results

The initial search yielded 358 abstracts, from which 21 articles were reviewed and 11 articles (n = 6,747) were included. Studies included were case‐control (64%) or cross‐sectional (36%) with evidence level 3b. On the Newcastle‐Ottawa scale, the mean quality assessment score for case‐control and cross‐sectional studies was 7.4 (maximum of 9) and 7.0 (maximum of 10), respectively. A statistically significant association between diabetes and olfaction compared with controls was found in 6 (55%) of the 11 articles. Four studies were eligible for meta‐analysis, which yielded an overall odds of having OI with diabetes as 1.58 times more likely than in control groups (95% CI [1.16, 2.16]; I² = 10.3%).

Conclusions

The reviewed studies support a significant association between diabetes and OI. Further studies are warranted to characterize this association.

Level of Evidence

3a

The Association Between Diabetes and Olfactory Function in Adults

Diabetes is a significant chronic disease that in limited studies has been linked with olfactory dysfunction. We investigated the cross-sectional association between diabetes and olfactory dysfunction in 3151 adults aged ≥40 years who participated in US National Health and Nutrition Examination Survey 2013-2014 with information on olfactory dysfunction and diabetes. Diabetes was defined from fasting serum glucose ≥126 mg/dL, oral glucose tolerance test ≥200 mg/dL, HbA1c levels ≥6.5%, physician-diagnosed diabetes, or current use of oral hypoglycemic agents and/or insulin. Self-reported olfactory dysfunction was defined as a positive answer to any of the following questions: 1) "Have you had problem with smell in the past 12 months?"; 2) "Have you had a change in the ability to smell since age 25?", or 3) "Do you have phantom smells?". Participants were considered to have severe hyposmia or anosmia if they had <5 correct answers in the 8-item pocket smell test. Analyses were adjusted for the main confounders, including olfactory dysfunction risk factors. Compared to non-diabetics, diabetics under insulin treatment showed a higher prevalence of phantom odors [OR(95% CI): 2.42 (1.16; 5.06)] and a non-significant higher prevalence of severe hyposmia/anosmia [OR(95% CI): 1.57 (0.89; 2.78)]. Amongst diabetics, there was a significant trend to severe hyposmia/anosmia for those on more aggressive treatments [OR (95% CI) including oral and insulin treatment compared to those who reported no use of drug treatment, respectively: 1.33 (0.60; 2.96) and 2.86 (1.28; 6.40); P trend 0.01]. No association was observed between diabetes duration and prevalence of olfactory dysfunction.

Sensory-specific impairment among older people. An investigation using both sensory thresholds and subjective measures across the five senses

Age-related sensory impairment is a slow and gradual progress, which affects multiple modalities. Two contradictory hypotheses exist about the age-related decline of sensory thresholds. The common factor theory assumes one underlying factor-which accounts for the loss of several sensory modalities simultaneously-and the specific factor theory predicts that the sensory decline is uncorrelated between different modalities. In this study, we aimed to explore whether (i) there is a common factor of sensory thresholds in older people, (ii) older people assume that sensory decline in one modality also affects other modalities, (iii) there is a relation between sensory threshold and the subjective assessment of sensory function. This was accomplished by collecting both threshold measures and self-reported ratings for smell, hearing, taste, vision, and touch function in a group of 104 older people (mean age: 67.2 years; SD: 9.85; range: 50-100 years). Results indicated that there was no common factor of sensory thresholds, hence an impairment in one modality did not necessarily imply a shortfall in other modalities. In contrast, our results suggested one or two common factor(s) for the participants' ratings. Participants who reported a diminished function in one sense tended to generalize this rating to the other senses as well. The correspondence between subjective ratings and sensory thresholds was relatively good for vision and audition, although no correlations were observed for the other domains. These findings have implications for clinicians, suggesting that subjective measures should be combined with sensory threshold measurements when evaluating sensory dysfunction. Also, these data convey a positive message for older people and their physicians by showing that loss in one sensory modality does not necessarily generalize to losses across all sensory modalities.

Differences in the Density of Fungiform Papillae and Composition of Saliva in Patients With Taste Disorders Compared to Healthy Controls

This study investigated the relation of the fungiform taste papillae density and saliva composition with the taste perception of patients suffering from diagnosed taste disorders. For this purpose, 81 patients and 40 healthy subjects were included. Taste was measured by means of regional and whole mouth chemosensory tests, and electrogustometry. Olfaction was assessed using the Sniffin Sticks. Fungiform papillae were quantified using the "Denver Papillae Protocol for Objective Analysis of Fungiform Papillae". In addition, salivary parameters [flow rate, total proteins, catalase, total anti-oxidative capacity (TAC), carbonic anhydrase VI (caVI), and pH] were determined and the Beck Depression Inventory was administered. Patients showed less taste papillae compared to healthy subjects. The number of papillae correlated with total taste strip score and salivary flow rate. Regarding salivary parameters, the flow rate, protein concentration, and TAC of patients were higher compared to controls. In addition, salivary flow rate, protease, caVI, and catalase values correlated with the summed taste strip score. Regarding various taste disorders, salty-dysgeusia patients showed the lowest taste test scores compared to those with bitter or metal-dysgeusia. Olfactory function of patients was significantly worse compared to healthy controls. This difference was most pronounced for ageusia patients. Compared to controls, patients also exhibited higher depressive symptoms. The density of fungiform papillae seemed to be positively associated with taste perception. Furthermore, patients exhibited changes in saliva composition (higher salivary flow rate, increased protein concentration, proteolysis, and TAC) compared to controls indicating that assessment of saliva may be critical for the diagnostic procedure in taste disorders.

Smoking and olfactory dysfunction: A systematic literature review and meta-analysis

OBJECTIVES/HYPOTHESIS

A systematic review and meta-analysis of the literature was undertaken, examining the association between tobacco smoking and olfactory function in humans, utilizing PubMed and Web of Science (1970-2015) as data sources.

STUDY DESIGN

Systematic literature review and meta-analysis.

METHODS

This database review of studies of smoking and olfaction, with a focus on identifying high-quality studies (based on modified versions of the Newcastle-Ottawa Scale), used validated olfactory tests among the generally healthy population.

RESULTS

We identified 11 studies meeting inclusion criteria. Of 10 cross-sectional studies, two were excluded from meta-analysis because the cohorts they studied were included in another article in the review. In meta-analysis, current smokers had substantially higher odds of olfactory dysfunction compared to never smokers (odds ratio [OR] = 1.59, 95% confidence interval [CI] = 1.37-1.85). In contrast, former smokers were found to have no difference in risk of impaired olfaction compared to never smokers (OR = 1.05, 95% CI = 0.91-1.21). The single longitudinal study reviewed found a trend toward increased risk of olfactory decline over time in ever smokers; this trend was stronger in current as compared to former smokers.

CONCLUSIONS

Current smoking, but not former smoking, is associated with significantly increased risk of olfactory dysfunction, suggesting that the effects of smoking on olfaction may be reversible. Future studies that prospectively evaluate the impact of smoking cessation on improvement in olfactory function are warranted.

LEVEL OF EVIDENCE

N/A. Laryngoscope, 127:1753-1761, 2017.

Global Sensory Impairment in Older Adults in the United States

OBJECTIVES

To determine whether there may be a common mechanism resulting in global sensory impairment of the five classical senses (vision, smell, hearing, touch, and taste) in older adults.

DESIGN

Representative, population-based study.

SETTING

National Social Life, Health, and Aging Project.

PARTICIPANTS

Community-dwelling U.S. adults aged 57 to 85.

MEASUREMENTS

The frequency with which impairment co-occurred across the five senses was estimated as an integrated measure of sensory aging. It was hypothesized that multisensory deficits would be common and reflect global sensory impairment that would largely explain the effects of age, sex, and race on sensory dysfunction.

RESULTS

Two-thirds of subjects had two or more sensory deficits, 27% had just one, and 6% had none. Seventy-four percent had impairment in taste, 70% in touch, 22% in smell, 20% in corrected vision, and 18% in corrected hearing. Older adults, men, African Americans, and Hispanics had greater multisensory impairment (all P < .01). Global sensory impairment largely accounted for the effects of age, sex, and race on the likelihood of impairment in each of the five senses.

CONCLUSION

Multisensory impairment is prevalent in older U.S. adults. These data support the concept of a common process that underlies sensory aging across the five senses. Clinicians assessing individuals with a sensory deficit should consider further evaluation for additional co-occurring sensory deficits.