[Screening of olfaction with smell diskettes]

Odor dilution sorting as a clinical test of olfactory function: normative values and reliability data

Clinical assessment of an individual's sense of smell has gained prominence, but its resource-intensive nature necessitates the exploration of self-administered methods. In this study, a cohort of 68 patients with olfactory loss and 55 controls were assessed using a recently introduced olfactory test. This test involves sorting 2 odorants (eugenol and phenylethyl alcohol) in 5 dilutions according to odor intensity, with an average application time of 3.5 min. The sorting task score, calculated as the mean of Kendall's Tau between the assigned and true dilution orders and normalized to [0,1], identified a cutoff for anosmia at a score ≤ 0.7. This cutoff, which marks the 90th percentile of scores obtained with randomly ordered dilutions, had a balanced accuracy of 89% (78% to 97%) for detecting anosmia, comparable to traditional odor threshold assessments. Retest evaluations suggested a score difference of ±0.15 as a cutoff for clinically significant changes in olfactory function. In conclusion, the olfactory sorting test represents a simple, self-administered approach to the detection of anosmia or preserved olfactory function. With balanced accuracy similar to existing brief olfactory tests, this method offers a practical and user-friendly alternative for screening anosmia, addressing the need for resource-efficient assessments in clinical settings.

Olfactory Function and Olfactory Disorders

The sense of smell is important. This became especially clear to patients with infection-related olfactory loss during the SARS-CoV-2 pandemic. We react, for example, to the body odors of other humans. The sense of smell warns us of danger, and it allows us to perceive flavors when eating and drinking. In essence, this means quality of life. Therefore, anosmia must be taken seriously. Although olfactory receptor neurons are characterized by regenerative capacity, anosmia is relatively common with about 5 % of anosmic people in the general population. Olfactory disorders are classified according to their causes (e. g., infections of the upper respiratory tract, traumatic brain injury, chronic rhinosinusitis, age) with the resulting different therapeutic options and prognoses. Thorough history taking is therefore important. A wide variety of tools are available for diagnosis, ranging from short screening tests and detailed multidimensional test procedures to electrophysiological and imaging methods. Thus, quantitative olfactory disorders are easily assessable and traceable. For qualitative olfactory disorders such as parosmia, however, no objectifying diagnostic procedures are currently available. Therapeutic options for olfactory disorders are limited. Nevertheless, there are effective options consisting of olfactory training as well as various additive drug therapies. The consultation and the competent discussion with the patients are of major importance.

How Does Hedonic Aroma Impact Long-Term Anxiety, Depression, and Quality of Life in Women with Breast Cancer? A Cross-Lagged Panel Model Analysis

Depression and anxiety are common symptoms during and after adjuvant chemotherapy treatment for breast cancer (BC), with implications on quality of life (QoL). The present study evaluates the temporal relationship between anxiety, depression, and QoL (primary outcomes), as well as the impact of hedonic aroma (essential oils) on this relationship. This is a secondary analysis of a previously reported randomized controlled trial, with two groups: an experimental group (n = 56), who were subjected to the inhalation of a self-selected essential oil during chemotherapy, and a control group (n = 56), who were only subjected to the standard treatment. The hedonic aroma intervention occurred in the second (T1), third (T2), and fourth (T3) chemotherapy sessions, three weeks apart from each other. The follow-up (T4) assessments took place three months after the end of the treatment. Cross-lagged panel models were estimated in the path analysis framework, using structural equation modeling methodology. Regarding the control group, the cross-lagged panel model showed that anxiety at T1 predicted anxiety at T3, which in turn predicted both QoL and depression at T4. In the experimental group, hedonic aroma intervention was associated with stability of anxiety and QoL over time from T1 to T3, with no longitudinal prediction at T4. For women undergoing standard chemotherapy treatment, anxiety was the main longitudinal precursor to depression and QoL three months after chemotherapy. Thus, essential oils could complement chemotherapy treatment for early-stage BC as a way to improve long-term emotional and QoL-related adjustment.

A case report of allergic fungal rhinosinusitis managed with Dupilumab

Introduction

Allergic fungal rhinosinusitis (AFRS) is a subtype of chronic rhinosinusitis with nasal polyps. It is characterized by eosinophilic mucin, which results from an inflammatory reaction to non-invasive fungal hyphae in the rhino-sinuses. It is clinically recognizable due to the criteria set by Bent and Kuhn. The treatment approach is multimodal, and the main treatment approach is surgical debridement, followed by a course of oral and/or topical corticosteroids to decrease recurrence post-surgery. This case report aims to illustrate the effect of Dupilumab, on the number of relapse episodes in a patient and the associated parameters.

Case presentation

Herein we report a case of a 40-year-old woman referred to our institution as a case of refractory AFRS for which she underwent four functional endoscopic sinus surgeries (FESS) and was on maximum medical treatment. She presented with complaints of facial fullness and pain, headache, and purulent discharge. After another trial of surgery which did not control her symptoms, she was assessed for criteria to start biological treatment. The symptoms were successfully controlled after initiation of the agent, and she was followed up using multiple subjective and objective measures.

Conclusion

AFRS is a non-invasive immune-mediated sub-clinical entity of chronic rhinosinusitis. A multimodal approach to its treatment based on surgical debridement with medical therapy has shown positive outcomes. In this case we present significant improvement after administering Dupilumab; therefore, suggesting its addition to the treatment regimen of refractory AFRS.

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Allergic fungal rhinosinusitis is a subtype of chronic rhinosinusitis with nasal polyps.

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The distinguishing feature of allergic fungal rhinosinusitis is high immunoglobulin E.

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Multimodal approach with the mainstay being surgery is the treatment method followed for allergic fungal rhinosinusitis.

Predictive Value of Odor Identification for Incident Dementia: The Shanghai Aging Study

OBJECTIVE

This study aimed to evaluate the value of odors in the olfactory identification (OI) test and other known risk factors for predicting incident dementia in the prospective Shanghai Aging Study.

METHODS

At baseline, OI was assessed using the Sniffin' Sticks Screening Test 12, which contains 12 different odors. Cognition assessment and consensus diagnosis were conducted at both baseline and follow-up to identify incident dementia. Four different multivariable logistic regression (MLR) models were used for predicting incident dementia. In the no-odor model, only demographics, lifestyle, and medical history variables were included. In the single-odor model, we further added one single odor to the first model. In the full model, all 12 odors were included. In the stepwise model, the variables were selected using a bidirectional stepwise selection method. The predictive abilities of these models were evaluated by the area under the receiver operating characteristic curve (AUC). The permutation importance method was used to evaluate the relative importance of different odors and other known risk factors.

RESULTS

Seventy-five (8%) incident dementia cases were diagnosed during 4.9 years of follow-up among 947 participants. The full and the stepwise MLR model (AUC = 0.916 and 0.914, respectively) have better predictive abilities compared with those of the no- or single-odor models. The five most important variables are Mini-Mental State Examination (MMSE) score, age, peppermint detection, coronary artery disease, and height in the full model, and MMSE, age, peppermint detection, stroke, and education in the stepwise model. The combination of only the top five variables in the stepwise model (AUC = 0.901 and sensitivity = 0.880) has as a good a predictive ability as other models.

CONCLUSION

The ability to smell peppermint might be one of the useful indicators for predicting dementia. Combining peppermint detection with MMSE, age, education, and history of stroke may have sensitive and robust predictive value for dementia in older adults.

Psychophysical testing of smell and taste function

The senses of smell and taste are largely underappreciated by laypersons and medical professionals alike. Unlike vision, hearing, balance, and touch, they are rarely evaluated quantitatively in the clinic, even though hundreds of thousands of persons seek medical help annually for disorders of these senses. Chemosensory disorders impact quality of life, including the flavor of foods and beverages, and compromise the ability to detect such environmental hazards as fires, leaking natural gas, and spoiled foodstuffs. Moreover, olfactory dysfunction can be a harbinger for Alzheimer's and other neurodegenerative diseases, and is known to triple the likelihood of mortality in older persons over the course of 4 or 5 years. Without accurate testing, one cannot establish the veracity of a patient's complaint, the probability of malingering, the impact of treatments, and whether the degree of dysfunction is normal relative to a patient's age and sex. This chapter provides basic information as to how to measure both the senses of smell and taste, as well as normative data for several clinical smell and taste tests.

Measurement of chemosensory function

Although hundreds of thousands of patients seek medical help annually for disorders of taste and smell, relatively few medical practitioners quantitatively test their patients' chemosensory function, taking their complaints at face value. This is clearly not the approach paid to patients complaining of visual, hearing, or balance problems. Accurate chemosensory testing is essential to establish the nature, degree, and veracity of a patient's complaint, as well as to aid in counseling and in monitoring the effectiveness of treatment strategies and decisions. In many cases, patients perseverate on chemosensory loss that objective assessment demonstrates has resolved. In other cases, patients are malingering. Olfactory testing is critical for not only establishing the validity and degree of the chemosensory dysfunction, but for helping patients place their dysfunction into perspective relative to the function of their peer group. It is well established, for example, that olfactory dysfunction is the rule, rather than the exception, in members of the older population. Moreover, it is now apparent that such dysfunction can be an early sign of neurodegenerative diseases such as Alzheimer's and Parkinson's. Importantly, older anosmics are three times more likely to die over the course of an ensuring five-year period than their normosmic peers, a situation that may be averted in some cases by appropriate nutritional and safety counseling. This review provides the clinician, as well as the academic and industrial researcher, with an overview of the available means for accurately assessing smell and taste function, including up-to-date information and normative data for advances in this field.

Office Procedures for Quantitative Assessment of Olfactory Function

Background

Despite the importance of the sense of smell for establishing the flavor of foods and beverages, as well as protecting against environmental dangers, this primary sensory system is commonly ignored by the rhinologist.

Methods

In this article basic issues related to practical measurement of olfactory function in the clinic are described and examples of the application of the two most common paradigms for such measurement—odor identification and detection–are presented. A listing is made of the 27 olfactory tests currently used clinically, along with their strengths and weaknesses. A brief review of common nasosinus-related disorders for which quantitative olfactory testing has been performed is provided.

Results

Although many psychophysical tests are available for quantifying olfactory loss, it is apparent that a number are limited in terms of practicality, sensitivity, and reliability. In general, sensitivity and reliability are positively correlated with test length. Given the strengths of the more reliable forced-choice pyschophysical tests and the limitations of electrophysiological tests, the common distinction between “subjective” and “objective” tests is misleading and should not be used. Complete recovery of olfactory function, as measured quantitatively, rarely follows surgical or medical interventions in patients with rhinosinusitis.

Conclusion

Given the availability of practical clinical olfactory tests, the modern rhinologist can easily quantify cranial nerve (CN) I function. The application of such tests has led to a new understanding of the effects of nasal disease on olfactory function. Except in cases of total or near-total nasal obstruction, olfactory and airway patency measures usually are unrelated, in accord with the concept that rhinosinusitis primarily influences olfactory function by apoptotic pathological changes within the olfactory neuroepithelium.

Apo E4 Alleles and Impaired Olfaction as Predictors of Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia that affects more than 5 million Americans. It is the only disease among the 10 causes of death that cannot be slowed or cured, thus raising the need for identification of early preclinical markers that could be the focus of preventative efforts. Although evidence is escalating that abnormalities in olfactory structure and function precede AD development and early cognitive impairments by one or more decades, the importance of olfaction is largely overlooked in AD, and such testing is not routinely performed in neurology clinics. Nevertheless, research using the olfactory model, has begun to advance our understanding of the preclinical pathophysiology of AD. Notably, an interesting series of studies is beginning to illuminate the relationship between Apolipoprotein E (ApoE) ε4 polymorphism and olfactory dysfunction and late-onset Alzheimer's disease. In this article, we reviewed present research on the significance of ApoE and olfaction to AD, summarized current studies on the associations and mechanisms of ApoE and olfactory dysfunction, and highlighted important gaps for future work to further advance the translational application of the olfactory paradigm to early, preclinical diagnosis and treatment of AD.

Perception of odors and tastes in autism spectrum disorders: A systematic review of assessments

Olfaction and gustation are major sensory functions implied in processing environmental stimuli. Some evidences suggest that loss of olfactory function is an early biomarker for neurodegenerative disorders and atypical processing of odor and taste stimuli is present in several neurodevelopmental disorders, notably in Autism Spectrum Disorders (ASD). In this paper, we conducted a systematic review investigating the assessments of olfaction and gustation with psychophysics methods in individuals with ASD. Pubmed, PMC and Sciencedirect were scrutinized for relevant literature published from 1970 to 2015. In this review, fourteen papers met our inclusion criteria. They were analyzed critically in order to evaluate the occurrence of olfactory and gustatory dysfunction in ASD, as well as to report the methods used to assess olfaction and gustation in such conditions. Regarding to these two senses, the overall number of studies is low. Most of studies show significant difference regarding to odor or taste identification but not for detection threshold. Overall, odor rating through pleasantness, intensity and familiarity do not differ significantly between control and individuals with ASD. The current evidences can suggest the presence of olfactory and gustatory dysfunction in ASD. Therefore, our analysis show a heterogeneity of findings. This is due to several methodological limitations such as the tools used or population studied. Understanding these disorders could help to shed light on other atypical behavior in this population such as feeding or social behavior. Autism Res 2017, 0: 000-000. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1045-1057. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Olfaction deterioration in cognitive disorders in the elderly

BACKGROUND

Parkinson's and Alzheimer's diseases are widespread neurodegenerative pathologies. Parkinson's disease affects about 1 % of the population over the age of 65 years, while Alzheimer is considered the most common cause of dementia, with an annual incidence of 1 % in persons aged 65 years. It has been demonstrated that both these neurodegenerative diseases are associated with smell dysfunction.

AIM

The aim of the present review is to describe briefly modern olfactory evaluation tools as well as the importance of olfactory sensitivity screening in the elderly, especially where cognitive disorders, such as Alzheimer's or Parkinson's diseases, are suspected.

METHODS

A brief literature review focusing on the basic principle of smell tests is illustrated together with their application in elderly patients affected by cognitive disorders, in particular Parkinson's and Alzheimer's diseases.

RESULTS/CONCLUSIONS

Alzheimer's and Parkinson's diseases are both neurodegenerative disorders typically found in the elderly. As both diseases are characterized by the early presence of dysosmia, simple validated smell tests could very well help clinicians in the early diagnosis of these neuropathological conditions. Elderly patients complaining of smell loss and found to be dysosmic, by means of validated olfactory tests, should be neurologically evaluated as early as possible to detect slight motor abnormalities in an at-risk population.

[Formula: see text]Olfaction in autism spectrum disorders: A systematic review

Olfactory function is a well-known early biomarker for neurodegeneration and neural functioning in the adult population, being supported by a number of brain structures that could be dysfunctioning in neurodegenerative processes. Evidence has suggested that atypical sensory and, particularly, olfactory processing is present in several neurodevelopmental conditions, including autism spectrum disorders (ASDs). In this paper, we present data obtained by a systematic literature review, conducted according to PRISMA guidelines, regarding the possible association between olfaction and ASDs, and analyze them critically in order to evaluate the occurrence of olfactory impairment in ASDs, as well as the possible usefulness of olfactory evaluation in such conditions. The results obtained in this analysis suggested a possible involvement of olfactory impairment in ASDs, underlining the importance of olfactory evaluation in the clinical assessment of ASDs. This assessment could be potentially included as a complementary evaluation in the diagnostic protocol of the condition. Methods for study selection and inclusion criteria were specified in advance and documented in PROSPERO protocol #CRD42014013939.

Quantitative Validation of the n-Butanol Sniffin' Sticks Threshold Pens

Odorant pens are used by medical practitioners and researchers to assess olfactory dysfunction. Despite their routine use, there are currently no data on the gas-phase odorant concentrations released from the pen tips or whether these concentrations scale linearly with the aqueous-phase concentrations inside the pens. The commercially available Sniffin' Sticks odor threshold test containing n-butanol was chosen for evaluation. The gas-phase concentration of n-butanol at the tip of each pen was measured directly in a new set of pens via proton-transfer-reaction mass spectrometry (PTR-MS). Measurements were additionally made on the same pens after 6 months and two older pen sets, namely a 3-year-old (used) and 4-year-old (new) set. Furthermore, application-related tests were made to determine the performance of the pens during routine use and under stress. These data demonstrate that the gas-phase n-butanol concentrations of the threshold pens are linear over the entire set, both for brand-new pens and 6 months later; this reflects the expected performance that was previously only assumed. Furthermore, the application-simulation tests demonstrated a good performance of the pens when used according to their intended protocol. Measurements of the older pen sets suggest that storage conditions are more critical than usage for pen stability. The present findings confirm that the n-butanol odorant pens are an appropriate tool for threshold testing, provided they are stored and handled correctly. Figureᅟ

Adapting the Sniffin' Sticks olfactory test to diagnose Parkinson's disease in Estonia

The aim of the study was to develop a culturally adapted translation of the 12-item smell identification test from Sniffin' Sticks (SS-12) for the Estonian population in order to help diagnose Parkinson's disease (PD).

METHODS

A standard translation of the SS-12 was created and 150 healthy Estonians were questioned about the smells used as response options in the test. Unfamiliar smells were replaced by culturally familiar options. The adapted SS-12 was applied to 70 controls in all age groups, and thereafter to 50 PD patients and 50 age- and sex-matched controls.

RESULTS

14 response options from 48 used in the SS-12 were replaced with familiar smells in an adapted version, in which the mean rate of correct response was 87% (range 73-99) compared to 83% with the literal translation (range 50-98). In PD patients, the average adapted SS-12 score (5.4/12) was significantly lower than in controls (average score 8.9/12), p < 0.0001. A multiple linear regression using the score in the SS-12 as the outcome measure showed that diagnosis and age independently influenced the result of the SS-12. A logistic regression using the SS-12 and age as covariates showed that the SS-12 (but not age) correctly classified 79.0% of subjects into the PD and control category, using a cut-off of <7 gave a sensitivity of 76% and specificity of 86% for the diagnosis of PD.

CONCLUSIONS

The developed SS-12 cultural adaption is appropriate for testing olfaction in Estonia for the purpose of PD diagnosis.

Olfication - a clinical approach

Olfactory dysfunction usually occurs secondary to ENT causes, and most patients with olfactory problems prefer to consult an otolaryngologist. 1a some cases the ENT surgeon is required to inculcate a systematic approach while dealing with such patients in order to screen the possibility of other causes (apart from ENT). He may in turn either collaborate with another specialist (neurologist, ophthalmologist, neurosurgeon) for proper diagnostic work- up or otherwise counsel the patient in case of a benign prognosis. Thus a basic knowledge about the applied pathophysiology of olfaction for its proper clinical approach is a must for every practicing ENT surgeon. We present the gist of the experience with olfaction at the Smell and Taste Center of the University of Pennsylvania USA that is relevant to the practicing otolaryngotogist. We present the information in two complementary parts: a clinical approach and its quantification and management which will be published in a subsequent issue of this journal.

Amount of airflow required for olfactory perception in laryngectomees: a prospective interventional study

OBJECTIVES

To determine minimum airflow rate required for olfactory stimulation in successfully rehabilitated laryngectomised patients after learning the polite yawning technique (PYT) and to confirm the hypothesis that sense of smell is rehabilitated once the nasal airflow is re-established.

DESIGN

Prospective open interventional trial.

SETTING

Tertiary academic hospital.

PARTICIPANTS

The study population comprised 100 laryngectomised patients. The control group consisted of 100 non-laryngectomised patients of similar age and sex. Rhinomanometry was used to measure air flow in the right and left nostrils, respectively, while the Smell Diskettes Olfaction test (SDOT) was used to test each individual's sense of smell.

MAIN OUTCOME MEASURES

The primary endpoint was increasing the airflow, while the secondary endpoint was improvement in the Smell Diskettes Olfaction test score after learning the polite yawning technique.

RESULTS

The difference in the Smell Diskettes Olfaction test results before and after introducing the polite yawning technique was statistically significant (F = 53.077; P < 0.001). The number of accurately identified odours increased with each measurement. There was a significant difference among rhinomanometric measurements of airflow through the right (F = 65.002; P < 0.001) and left nostrils (F = 75.465; P < 0.001). Nasal airflow improved with each measurement. The minimum airflow required for olfactory stimulation in successfully rehabilitated patients was approximately 60 cm(3) /s. The control group had considerably better airflow in both nostrils than the laryngectomised group. The difference between the total number of rehabilitated (normosmic) patients (48%) in the laringectomised group and normosmic participants (56%) in the control group (z = 1.132; P = 0.129) was not statistically significant.

CONCLUSION

The number of odours identified by laryngectomised patients increased with the volume of nasal airflow. The number of patients with rehabilitated olfactory function approximated the percentage of normosmic individuals in the non-laryngectomised population. These findings confirm the hypothesis that sense of smell is rehabilitated once the nasal airflow is re-established.

Development of a 15-item odour discrimination test (Düsseldorf Odour Discrimination Test)

A key function of the olfactory system is the detection of differences in odour quality. Therefore, a test was developed to assess odour discrimination ability in normosmic humans. Out of six monomolecular substances (capric acid, coumarin, eugenol, geraniol, phenylethyl alcohol, and vanillin) quaternary mixtures were prepared. Within one item, three odour mixtures were presented (triangle forced-choice procedure). The deviant odour contained the same substances as the two remaining odours; however, the proportions were changed. Study 1 (120 participants) aimed to select items that contribute to a high internal consistency. Study 2 (104 participants) assessed test-retest reliability, parallel test reliability and test validity. Out of 45 items, a 15-item test (Düsseldorf Odour Discrimination Test, DODT) with an internal consistency of 0.61 and medium item difficulties was prepared. The test-retest reliability of the DODT was 0.66 (test interval = 4 weeks) and the parallel test reliability 0.42. The DODT correlated significantly with the University of Pennsylvania Smell Identification Test and to a lesser extent with the phenylethyl alcohol odour threshold test. As the DODT did not correlate with the odour discrimination test of the Sniffin' Sticks, the two tests seem to measure different performances of the olfactory system.

A short olfactory test based on the identification of three odors

Numerous psychophysical tests of olfactory function have been developed during the last 30 years. However, although most tests provide accurate results, testing typically requires time which is not available in clinical routine. The aim of the present study was to investigate results from a test based on the identification of three odors only. A total of 500 subjects (patients with olfactory loss plus healthy controls) were included. They received (1) detailed olfactory testing, and (2) the 3-item odor identification test, the so-called q-Sticks. On a group level the q-Sticks clearly separated between anosmic, hyposmic, and normosmic subjects. In addition, q-Sticks scores were significantly higher in women compared to men, and in younger compared to older subjects. With regard to a q-Sticks score of 0, the new test had a very high specificity of 96% and a moderate sensitivity of 66%. Although the q-Sticks must not be seen as a replacement of more extensive and, therefore, more accurate olfactory tests, they allow the investigator to identify anosmia with a very high specificity. Considering the test's portability, ease of administration, longevity, and possibility to be used over and over again, it can be expected to find its way into the clinician's routine or screening diagnostic armamentarium.

Olfaction in dentistry

Practitioners of oral medicine frequently encounter patients with complaints of taste disturbance. While some such complaints represent pathological processes specific to the gustatory system, per se, this is rarely the case. Unless taste-bud mediated qualities such as sweet, sour, bitter, salty, umami, chalky, or metallic are involved, 'taste' dysfunction inevitably reflects damage to the sense of smell. Such 'taste' sensations as chicken, chocolate, coffee, raspberry, steak sauce, pizza, and hamburger are dependent upon stimulation of the olfactory receptors via the nasopharynx during deglutition. In this paper, we briefly review the anatomy, physiology, and pathophysiology of the olfactory system, along with means for clinically assessing its function. The prevalence, etiology, and nature of olfactory disorders commonly encountered in the dental clinic are addressed, along with approaches to therapy and patient management.

Die Untersuchung des Riechvermögens

Olfactory disorders are common. Functional anosmia is present in about 5-6% of the general population, while from the age of about 55 years the olfactory sense is restricted in about 25% of cases. A precise examination is necessary to describe the patient's symptoms and ascertain possible reasons for them. As far as diagnosis and possible treatment of olfactory or gustatory disorders are concerned, the main advantage allowing progress is the availability of standardised methods of testing the chemical senses. In this article procedures for orthonasal and retronasal psychophysical examination of the olfactory sense and the derivation of potentials evoked by olfactory stimuli are described. In addition, possible ways of examining the intranasal sensitivity of the trigeminal nerve and measuring the volume of the olfactory bulb, and also for immunochemical investigation of biopsies from the olfactory region, are discussed as possible means of reaching a diagnosis.

Olfactory dysfunction and its measurement in the clinic and workplace

OBJECTIVES

To provide an overview of practical means for quantitatively assessing the sense of smell in both the clinic and workplace. To address basic measurement issues, including those of test sensitivity, specificity, and reliability. To describe and discuss factors that influence olfactory function, including airborne toxins commonly found in industrial settings.

METHODS

Selective review and discussion.

RESULTS

A number of well-validated practical threshold and suprathreshold tests are available for assessing smell function. The reliability, sensitivity, and specificity of such techniques vary, being influenced by such factors as test length and type. Numerous subject factors, including age, sex, health, medications, and exposure to environmental toxins, particularly heavy metals, influence the ability to smell.

CONCLUSIONS

Modern advances in technology, in conjunction with better occupational medicine practices, now make it possible to reliably monitor and limit occupational exposures to hazardous chemicals and their potential adverse influences on the sense of smell. Quantitative olfactory testing is critical to establish the presence or absence of such adverse influences, as well as to (a) detect malingering, (b) establish disability compensation, and (c) monitor function over time.

[Olfactory dysfunction due to nasal sinus disease. Causes, consequences, epidemiology, and therapy]

Olfaction not only contributes to our quality of life but, among other functions, it is also necessary for identifying potential dangers, e.g., fire or spoilt food. In general the value of olfaction is only recognized when the sense of smell is impaired or lost. Olfactory dysfunction is diagnosed according to its cause (e.g., sinonasal, post-traumatic, post-upper respiratory tract infection, neurodegenerative, and idiopathic). At present little is known about prognostic factors for predicting resolution of olfactory loss on an individual basis. In cases of impaired olfaction due to sinonasal disease, both conservative and operative treatments have been established. Corticoids are used both topically and systemically. In cases of severe mechanical obstructions or advanced stages of nasal polyposis, FESS (functional endoscopic sinus surgery) seems to be the state of the art.

Olfaction

The main and accessory olfactory systems have received considerable attention on the part of scientists and clinicians during the last decade, largely because of (a) quantum advances in understanding their genetically expressed receptor mechanisms, (b) evidence that their receptor cells undergo neurogenesis and both programmed and induced cell death, and (c) important technical and practical developments in psychophysical measurement. The latter developments have led to the proliferation of standardized olfactory testing in laboratories and clinics, and to the discovery that smell loss is among the first signs of a number of neurodegenerative diseases, including Alzheimer's disease and idiopathic Parkinson's disease. Recent controversial claims that humans possess a functioning vomeronasal system responsive to "pheromones" has added further interest in intranasal chemoreception. This review focuses on recent progress made in understanding olfactory function, emphasizing transduction, measurement, and clinical findings.