Temporary olfactory improvement in chronic rhinosinusitis with nasal polyps after treatment

Olfactory dysfunction and the role of stem cells in the regeneration of olfactory neurons

The prevalence of COVID-19 has drawn increasing attention to olfactory dysfunction among researchers. Olfactory dysfunction manifests in various clinical types, influenced by numerous pathogenic factors. Despite this diversity, the underlying pathogenesis remains largely elusive, contributing to a lack of standardized treatment approaches. However, the potential regeneration of olfactory neurons within the nasal cavity presents a promising avenue for addressing olfactory dysfunction effectively. Our review aims to delve into the current research landscape and treatment modalities concerning olfactory dysfunction, emphasizing etiology, pathogenesis, clinical interventions, and the role of stem cells in regenerating olfactory nerves. Through this comprehensive examination, we aim to provide valuable insights into understanding the onset, progression, and treatment of olfactory dysfunction diseases.

Olfactory cleft mucus eosinophil-derived neurotoxin better reflects olfactory loss than blood eosinophil counts in patients with chronic rhinosinusitis

BACKGROUND

Eosinophils are associated with olfactory dysfunction in chronic rhinosinusitis (CRS) and eosinophil-derived neurotoxin (EDN) is a sensitive marker of intense eosinophil activation. This study aimed to analyze olfactory cleft mucus and olfactory mucosa EDN levels and their association with olfactory dysfunction in CRS.

METHODS

We prospectively recruited 150 patients with CRS electing endoscopic sinus surgery and 25 healthy controls. Both superior turbinate biopsy specimens and olfactory cleft mucus were collected to analyze EDN levels. Sniffin' Sticks test scores, olfactory cleft computed tomography (CT) scores, and olfactory cleft endoscopy scale (OCES) were obtained. Multivariable logistic regression analysis was applied to analyze the predictability of EDN levels for olfactory dysfunction in CRS.

RESULTS

Chronic rhinosinusitis with olfactory dysfunction presented significantly higher olfactory mucosa (p = 0.016) and olfactory cleft mucus (p < 0.001) EDN levels than CRS without olfactory dysfunction. Mucus EDN levels were positively correlated with blood eosinophils (r = 0.625, p = 0.002), olfactory cleft CT scores (r = 0.738, p < 0.001), and OCES (r = 0.605, p = 0.004) in CRS. Furthermore, mucus EDN levels were significantly negatively correlated with threshold, discrimination, and identification (TDI) (r = -0.688), olfactory threshold (r = -0.606), olfactory discrimination (r = -0.608), and olfactory identification (r = -0.697) scores. After adjusting for patient demographics and comorbidities, mucus EDN levels were significantly associated with olfactory dysfunction in CRS (odds ratio = 2.162; p = 0.027). Mucus EDN levels showed a significantly better performance for predicting olfactory dysfunction than blood eosinophil counts (area under the curve, 0.873 vs. 0.764, p = 0.024).

CONCLUSION

Olfactory cleft mucus EDN level may be a better biomarker for predicting olfactory dysfunction in CRS than blood eosinophil counts.

Olfactory cleft mucus galectin-10 predicts olfactory loss in chronic rhinosinusitis

BACKGROUND

Eosinophils have been reported to be involved in the pathogenesis of olfactory fluctuation in chronic rhinosinusitis (CRS). Galectin-10 is more frequently associated with type 2 inflammation and potentially a sign of intense eosinophil activation.

OBJECTIVE

To explore olfactory cleft mucus and olfactory mucosa galectin-10 level and its association with olfactory dysfunction (OD) in CRS.

METHODS

We prospectively enrolled 50 patients with CRS and 15 healthy controls. Olfactory cleft mucus and superior turbinate biopsy specimens were collected to analyze galectin-10 levels and quantify tissue eosinophils. Psychophysical olfactory testing, olfactory cleft endoscopy scale, and olfactory cleft computed tomography scores were obtained. The predictability of galectin-10 levels for OD in patients with CRS was analyzed by multivariable logistic regression analysis.

RESULTS

Both olfactory cleft mucus and olfactory mucosa galectin-10 levels in patients with CRS with OD were significantly higher than those in patients with CRS without OD (all P < .001). Mucus galectin-10 levels were positively correlated with tissue eosinophils (r = 0.541, P = 0.002), olfactory cleft endoscopy scale (r = 0.498, P = 0.006), and olfactory cleft computed tomography scores (r = 0.432, P = 0.019) in patients with CRS. Mucus galectin-10 levels were negatively correlated threshold, discrimination, and identification (r = -0.589,  P = 0.001), olfactory threshold (r = -0.522, P = 0.003), olfactory discrimination (r = -0.488, P = 0.007), and olfactory identification (r = -0.466, P = 0.011) scores. After adjusting for patient demographics and comorbidities, mucus galectin-10 levels were significantly associated with OD in patients with CRS (odds ratio, 1.299; P = .008). Mucus galectin-10 levels greater than 8.975 ng/mL were the best predictor of OD in CRS.

CONCLUSION

Olfactory cleft mucus galectin-10 is highly associated with OD in CRS.

Presurgical olfactory function as an indicator of the outcome of functional endoscopic sinus surgery in chronic rhinosinusitis with nasal polyps

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) often leads to impaired olfactory function and reduced quality of life. When conservative treatments such as nasal irrigation and topical steroids fail, functional endoscopic sinus surgery (FESS) is often necessary, because it improves symptoms and enhances quality of life.

MATERIALS AND METHODS

A total of 88 patients was included in this prospective study. All subjects underwent an extensive examination both presurgically and 4 months after operations including nasal endoscopy and psychophysical olfactory testing (Sniffin' Sticks). Moreover, disease-specific quality of life was assessed and presurgical CT scans were rated regarding the opacification of the paranasal sinuses.

RESULTS

Presurgically psychophysical tests showed an overall olfactory dysfunction. Olfactory test results (TDI score) correlated with endoscopic (Lund-Kennedy and Lildtholdt score) and CT scores (Lund-Mackay and TOCS scores). Four months after surgery olfactory function was enhanced and quality of life significantly showed an overall improvement. However, the outcome was dependent on the extent of presurgical olfactory function: olfaction and quality of life improved most pronounced in anosmics compared to hyposmic and especially normosmic patients.

CONCLUSIONS

This study confirmed that FESS in CRSwNP leads to a significant improvement of both olfaction and disease-specific quality of life. Moreover, preoperative psychophysical assessment of the extent of olfactory dysfunction can help to objectively assess possible risks and expected benefits of the surgery in terms of olfaction and quality of life.

Olfactory dysfunction in cystic fibrosis: Impact of CFTR modulator therapy

BACKGROUND

Elexacaftor-tezacaftor-ivacaftor (ETI) improves pulmonary health and chronic rhinosinusitis (CRS) for people with cystic fibrosis (PwCF), however its impact on olfaction has not been investigated. Olfactory dysfunction impairs quality-of-life (QOL). This study evaluated the impact of ETI on multiple olfactory metrics.

METHODS

Adult PwCF/CRS with CF transmembrane conductance regulator genotype F508del/F508del or F508del/minimal function who clinically initiated ETI participated in a prospective, observational study. Endpoints included changes after 6 months of ETI in quantitative olfactory function (Smell Identification Test, SIT), olfactory QOL (Questionnaire of Olfactory Disorders, QOD) and percent olfactory cleft opacification (%OCO), representing superior nasal cavity inflammation where afferent olfactory neurons are concentrated.

RESULTS

30 PwCF/CRS met inclusion criteria; 25 completed the study. Mean ETI adherence was 93%. At baseline, participants were hyposmic (mean SIT 31.3), had significant %OCO (mean 65.6%), yet reported non-impaired olfactory QOL (mean QOD 6.1). At follow-up, mean SIT worsened mildly (p=0.009), mean %OCO remained stable (p=0.46), and mean QOD improved modestly (p=0.008). No outcomes were impacted by prior modulator use, genotype, nasal polyps, or CF-related diabetes. Prior sinus surgery was associated with QOD improvement (p=0.04). Increased (worse) baseline QOD scores and %OCO were associated with greater improvements (p<0.003), but not SIT (p=0.44).

CONCLUSIONS

ETI was not associated with improvement in quantitative olfaction or olfactory cleft opacification after 6 months. PwCF/CRS have hyposmia but do not report impairment in olfactory QOL. Further study to investigate mechanisms explaining olfactory dysfunction and whether olfaction improves with greater duration of ETI or in younger age groups is warranted.

Effects of Fluticasone Exhalation Delivery System in Patients With Chronic Rhinosinusitis With Nasal Polyps: A Systematic Review

BACKGROUND

Nasal sprays with corticosteroids deliver medication to the restricted areas including anterior and inferior parts of the nasal cavity. The fluticasone exhalation delivery system (EDS-FLU) has recently been proved to improve care by increasing superior/posterior intranasal corticosteroid deposition.

OBJECTIVE

This study aims to evaluate the efficacy of EDS-FLU in patients with chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODOLOGY

A systematic literature review using Pubmed, Embase, Cochrane Library, and Web of Science was conducted to identify studies assessing the effect of EDS-FLU on outcomes in patients with CRSwNP.

RESULTS

Of the initial 108 abstracts reviewed, 4 full-text articles were included. The 22-item sinonasal outcome test scores were significantly decreased in patients with CRSwNP after receiving EDS-FLU twice a day (93, 186, or 372 μg) for 16 weeks when compared with exhalation delivery system (EDS)-placebo (all P < .001). Patients with CRSwNP reported significant improvement of smell after receiving twice daily EDS-FLU twice a day (93, or 372 μg) for 4 weeks when compared with EDS-placebo (all P < .05). The proportions of patients achieving ≥1-point improvement in total polyp grade were significantly higher in EDS-FLU group and dose dependent, with the highest rates in the 372 μg group. The proportions of patients achieving polyp elimination were significantly higher in EDS-FLU group with the highest rates in the 372 μg group.

CONCLUSION

This is the first systematic review of the clinical outcomes in patients with CRSwNP treated with EDS-FLU. EDS-FLU produced significant improvements regarding the quality of life, smell, and endoscopic assessment of polyp grade.

Discordance Between Subjective and Objective Measures of Smell and Taste in US Adults

OBJECTIVE

Examine the rates and factors associated with under- and overreporting of subjective changes in smell or taste as compared with objective measures.

STUDY DESIGN

Cross-sectional analysis.

SETTING

National Health and Nutrition Examination Survey (2013-2014).

METHODS

We examined participants ≥40 years old who completed subjective questionnaires (smell, n = 3510; taste, n = 3089), validated objective 8-odor pocket smell tests, and NaCl/quinine taste tests. Over- and underreporting was determined by the difference in subjective and objective results. Univariate and multivariate logistic regression analyses incorporated sampling weights.

RESULTS

A majority of participants correctly classified impairment: smell (73.7%; 95% CI, 71.2%-76.1%) and taste (78.3%; 95% CI, 75.6%-80.7%). Age ≥65 years (odds ratio, 2.23; P = .001) was associated with underreporting impairment, and persistent cold symptoms (odds ratio, 2.15; P = .001) were associated with overreporting smell impairment. Smoke, onion, and natural gas scents were incorrectly identified more frequently by individuals aged ≥65 years after Bonferroni correction. No factors were associated with under- and overreporting taste impairment.

CONCLUSION

Although the concordance rate between subjective and objective assessment of smell and taste impairment remains high, we found that older age was associated with incorrect report of impairment. This suggests that the subjective perception of smell varies across demographical and clinical factors, and it is important to not overlook such factors in clinical practice. Potentially using a simplified odor assessment regularly in the clinical setting may aid in early detection and intervention.

Modulation of olfactory signal detection in the olfactory epithelium: focus on the internal and external environment, and the emerging role of the immune system

Detection and discrimination of odorants by the olfactory system plays a pivotal role in animal survival. Olfactory-based behaviors must be adapted to an ever-changing environment. Part of these adaptations includes changes of odorant detection by olfactory sensory neurons localized in the olfactory epithelium. It is now well established that internal signals such as hormones, neurotransmitters, or paracrine signals directly affect the electric activity of olfactory neurons. Furthermore, recent data have shown that activity-dependent survival of olfactory neurons is important in the olfactory epithelium. Finally, as olfactory neurons are directly exposed to environmental toxicants and pathogens, the olfactory epithelium also interacts closely with the immune system leading to neuroimmune modulations. Here, we review how detection of odorants can be modulated in the vertebrate olfactory epithelium. We choose to focus on three cellular types of the olfactory epithelium (the olfactory sensory neuron, the sustentacular and microvillar cells) to present the diversity of modulation of the detection of odorant in the olfactory epithelium. We also present some of the growing literature on the importance of immune cells in the functioning of the olfactory epithelium, although their impact on odorant detection is only just beginning to be unravelled.

Clinical Implications of Psychophysical Olfactory Testing: Assessment, Diagnosis, and Treatment Outcome

Purpose of Review

Olfactory dysfunction dramatically impairs quality of life with a prevalence of 20% in the general adult population. Psychophysical olfactory testing has been widely used to evaluate the ability to smell due to its validated utility and feasibility in clinic. This review summarizes the current literature regarding psychophysical olfactory testing and the clinical relevance of the olfactory testing with different components. Furthermore, the review highlights the diagnosis and treatment value of olfactory subtests in patients with olfactory dysfunction.

Recent Findings

With the accumulation of studies of psychophysical olfactory testing in olfactory disorders, the clinical relevance of olfactory testing with different components is expanding. Different olfactory domains present with distinct olfactory processing and cortical activity. Psychophysical assessment of olfaction with three domains reveals different levels of olfactory processing and might assist with analyzing the pathophysiologic mechanism of the various olfactory disorders. Furthermore, olfactory thresholds provided the largest amount of non-redundant information to the olfactory diagnosis. Sinonasal olfactory dysfunction and non-sinonasal-related olfactory dysfunction are emerging classifications of smell disorders with certain characteristics of olfactory impairment and different responses to the therapy including steroids, sinus surgery, and olfactory training.

Summary

These recent advancements should promote the understanding of psychophysical olfactory testing, the association between individual subcomponents and neurophysiological processes, and pave the way for precision assessment and treatment of the olfactory dysfunction.

Clinical characteristics and cytokine profiles of central-compartment-type chronic rhinosinusitis

BACKGROUND

The clinical characteristics of central-compartment-type chronic rhinosinusitis (CRS) in East Asian individuals are not clear. We sought to investigate the clinical features and the cytokine profiles of central-compartment-type CRS in our patient group.

METHODS

Adult patients diagnosed with bilateral CRS were recruited, and patients who had previously undergone sinus surgery and pansinusitis (Lund-Mackay scores >23) were excluded. Central-compartment-type CRS was defined by both endoscopic and radiological features. The symptoms, inhalant allergen sensitization status, endoscopic findings, and radiological assessments were recorded and compared between patients with central-compartment-type CRS and other types of CRS. We also examined the extent of tissue eosinophilia and specific cytokine protein levels (eosinophil cationic protein [ECP], myeloperoxidase [MPO], immunoglobulin E [IgE], interleukin [IL]-4, IL-5, and IL-13) in the sinonasal tissues.

RESULTS

Central-compartment-type CRS was found in 16 (23.9%) patients, and non-central-compartment-type CRS was found in 51 (76.1%) patients. Hyposmia or anosmia as the major symptom was more common in the central-compartment-type CRS group. The numbers of eosinophils in tissue and serum were significantly higher in the central-compartment-type CRS patients. The presence of allergen sensitization was not significantly different between groups. The levels of IL-5 and IL-13 were increased in middle turbinate tissues of patients with central-compartment-type CRS.

CONCLUSION

Central-compartment-type CRS was associated with hyposmia or anosmia, eosinophilic subtypes, and elevated levels of IL-5 and IL-13 in middle turbinate tissues but not necessarily correlated with allergic disease in our patients.

Smell and Taste Impairment in a Nationwide Sample of US Adults With Chronic Rhinosinusitis Symptoms

Objective

To estimate the prevalence of objectively confirmed olfactory and gustatory dysfunction in US adults reporting chronic rhinosinusitis (CRS) symptoms in a nationally representative database.

Study Design

Cross-sectional epidemiologic analysis.

Setting

Data were analyzed from the smell and taste component of the 2013-2014 NHANES data set (National Health and Nutrition Examination Survey).

Methods

Individuals reporting the presence of ≥2 cardinal CRS symptoms (nasal blockage, sinus pain, discolored mucus, and dysosmia) were identified as patients with a potential diagnosis of CRS. Associations were examined between the presence of CRS symptoms and both self-reported and objectively measured smell and taste.

Results

One-third (33%) of adults who have ≥2 CRS symptoms report subjective olfactory impairment, though only 18% of these adults have quantifiable olfactory dysfunction on objective testing. Of these adults, 27% report subjective taste impairment, but just 17% have quantifiable gustatory dysfunction on objective testing. The presence of ≥2 CRS symptoms was not significantly associated with objective olfactory or gustatory dysfunction, although the individual symptoms of subjective dysosmia and discolored mucus were associated with objectively confirmed olfactory dysfunction.

Conclusion

The prevalence of objective olfactory and gustatory dysfunction was higher among adults reporting the presence of ≥2 CRS symptoms, but the differences were not statistically significant. Specific sinonasal symptoms, including discolored mucus and subjective smell dysfunction, were significantly associated with objective smell impairment.

Type 1/type 2 inflammatory cytokines correlate with olfactory function in patients with chronic rhinosinusitis

BACKGROUND

Olfactory dysfunction secondary to chronic rhinosinusitis (CRS) has been highly associated with impaired quality of life. Asian CRS patients showed a distinct inflammatory profile, with less type 2 endotype compared with European and North American. This study aimed to explore the pattern of the inflammatory cytokines in CRS patients from China and their association with olfactory function.

METHODS

Institutional review board-approved prospective study in which the olfactory function of 71 CRS patients was assessed with Sniffin' Sticks before the nasal endoscopic surgery. A set of cytokines and inflammatory mediators including type 1 and type 2 inflammatory cytokines were measured in nasal mucus by using a multiplex flow cytometric bead assay (CBA). Baseline characteristics in CRS patients were collected and the Spearman r statistic was performed to assess the association of olfactory function with cytokines and inflammatory mediators.

RESULTS

A total of 71 nasal mucus samples of CRS patients, including 25 chronic rhinosinusitis without nasal polyposis (CRSsNP) patients and 46 chronic rhinosinusitis with nasal polyposis (CRSwNP) patients, were evaluated in this study. The nasal mucus levels of type 1 inflammatory cytokine IFN-γ (interferon-γ), type 2 inflammatory cytokines including IL-4, IL-5 and GM-CSF (granulocyte-macrophage colony-stimulating factor) and anti-inflammatory cytokine IL-10 were significantly and inversely correlated with olfactory function in total patients with CRS (r = -0.308, p = 0.009; r = -0.250, p = 0.036; r = -0.399, p = 0.001; r = -0.269, p = 0.023; r = -0.273, p = 0.021, respectively). In CRSsNP, the olfactory function was inversely correlated with levels of type 1 inflammatory cytokine TNF-α (tumor necrosis factor-α) (r = -0.637, p = 0.001) and IL-10 (r = -0.468, p = 0.018). Nevertheless, the olfactory function in CRSwNP was inversely correlated with type 2 inflammatory cytokines including IL-4 (r = -0.303, p = 0.041) and IL-5 (r = -0.383, p = 0.009).

CONCLUSION

Both type 1 and type 2 inflammatory cytokines may contribute to the pathogenesis of CRS-associated olfactory dysfunction in the Chinese population.

Superior turbinate eosinophilia predicts olfactory decline in patients with chronic rhinosinusitis

BACKGROUND

Predicting postoperative olfactory decline in patients with chronic rhinosinusitis (CRS) remains a considerable challenge.

OBJECTIVE

To evaluate patterns of postoperative olfactory function in patients with CRS and explore potential predictors of postoperative olfactory decline.

METHODS

A total of 76 patients with CRS electing endoscopic sinus surgery (ESS) were enrolled in this prospective study. Olfaction was assessed with Sniffin' Sticks preoperatively and 3 months postoperatively. Preoperative peripheral venous blood and superior turbinate at surgery were collected for eosinophil quantification. Olfactory cleft was evaluated by computed tomography and endoscopy. Postoperative olfactory decline was defined by a decrease in threshold-discrimination-identification (TDI) score more than 0 point. Multivariable logistic regression analysis was conducted to identify potential predictors associated with postoperative olfactory decline in TDI score.

RESULTS

A total of 30.26% of patients with CRS (23/76) presented with olfactory decline 3 months post-ESS. Patients with CRS with olfactory decline showed significantly higher preoperative tissue eosinophils (P < .001), blood eosinophil count (P = .002), blood eosinophil percentage (P = .009), and preoperative TDI scores (P = .017) than patients with CRS without olfactory decline. After adjusting for patient demographics and comorbidities, the preoperative tissue eosinophilia was significantly associated with patients with CRS with postoperative olfactory decline (odds ratio = 1.103; P = .038). An absolute count of 23.5 eosinophils per high-power field in superior turbinate was the best predictor of olfactory decline with the highest area under the receiver operating characteristic curve of 0.901.

CONCLUSION

Superior turbinate eosinophilia is highly associated with olfactory decline in patients with CRS 3 months after ESS.

The efficacy of diluted topical povidone-iodine rinses in the management of recalcitrant chronic rhinosinusitis: a prospective cohort study

PURPOSE

Recalcitrant chronic rhinosinusitis is a persistent inflammatory condition of the sinonasal mucosa despite adequate medical therapy and sinus surgery. This study aimed to demonstrate the effectiveness and safety of dilute povidone-iodine (PVP-I) sinonasal rinses as an adjunctive therapy.

METHODS

Prospective cohort study. Twenty-nine recalcitrant CRS patients with endoscopic evidence of ongoing inflammation and purulent discharge were prescribed 0.08% diluted PVP-I rinses. Changes to endoscopic modified Lund-Kennedy (MLK) scores at 7 weeks post-PVP-I rinsing served as the primary outcome measure.

RESULTS

The median MLK-discharge score significantly decreased in all patients by 1.50 points post-PVP-I rinsing (p value < 0.01). The total MLK score significantly decreased in all patients by 1.50 points (p value = 0.01). Up to a 17% reduction in serum inflammatory markers was measured post-PVP-I rinsing. Sinonasal culture revealed a shift from moderate-heavy growth to lighter bacterial growth overall. Subjective SNOT-22 scores significantly improved overall by ≥ 1 minimal clinically important difference (MCID > 12; baseline median = 33; follow-up median = 20; p value < 0.01; n = 22). TSH levels increased non-significantly within normal ranges (baseline median = 1.59 mU/L; follow-up median = 1.92 mU/L; p = 0.10; n = 15). Mucociliary clearance time increased non-significantly within normal ranges (baseline median = 9 min; follow-up median = 10 min; p value = 0.53; n = 17). Olfactory Sniffin'16 scores non-significantly decreased within age-related normal ranges (baseline median = 14; follow-up median = 13; p value = 0.72; n = 18).

CONCLUSION

A dilute 0.08% PVP-I sinonasal rinse as an ancillary therapy in recalcitrant CRS significantly reduces signs of infection alongside notable symptom improvement, without affecting thyroid function, mucociliary clearance or olfaction.

Recovery of smell sense loss by mepolizumab in a patient allergic to Dermatophagoides and affected by chronic rhinosinusitis with nasal polyps

Background

Chronic rhinosinusitis with nasal polyps (CRSwNP) frequently presents with dysfunction or loss of the sense of smell, resulting in a significant impairment in quality of life. The medical treatments currently available may improve the olfactory function in patients with CRSwNP, but such an outcome is generally only transitory. We report the case of a patient with CRSwNP who completely recovered from smell sense loss by treatment with mepolizumab.

Case presentation

The patient was a 62-year-old female who has severe asthma induced by allergy to Dermatophagoides and concomitant CRSwNP. Any treatment for the latter, including oral and injective corticosteroids, was unsuccessful in the loss of smell. Due to the satisfaction of admission criteria to mepolizumab treatment for severe asthma, treatment was initiated on March 2018, resulting in good clinical control of both asthma and CRSwNP, and particularly in complete recovery of the smell loss after 4 months of treatment and still persisting.

Conclusion

In this case report, the treatment with mepolizumab in a patient allergic to Dermatophagoides and affected by CRSwNP was associated with an improvement of anosmia. That finding may be explained by a reduction of the nasal obstruction by nasal polyps.

Systemic diseases and disorders

Alterations in the ability to smell or taste are of considerable consequence, impacting quality of life, safety, nutrition, and dietary activities. These primary senses are influenced by a wide range of systemic diseases and disorders that commonly involve the entire body. These include viral, bacterial, fungal, protozoal, cestode, and nematode infections that can spread throughout the gastric, lymphatic, neural, or circulatory systems as well as classic autoimmune disorders, collagen diseases, diabetes, and hypertension, and others. Although a considerable literature has evolved in which the function of both taste and smell has been assessed in a number of such disorders, quantitative chemosensory testing is still relatively rare with many disorders not receiving empirical assessment. Incongruent findings are not uncommon. This chapter reviews what is known about the influences of a wide spectrum of systemic diseases and disorders on the abilities to taste and smell.