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This article focuses on the change in olfaction and taste with aging. It discusses histopathology with an emphasis on age-related changes, causes of chemosensory dysfunction in the elderly, how to evaluate a patient with dysfunction, useful tests and imaging, clinical consequences of chemosensory impairments, and available treatment options.
A viral upper respiratory infection is one of the most commonly identified causes of olfactory loss, accounting for 20% to 30% of patients in most series. Given the ubiquitous nature of upper respiratory infections, it is not clear what predisposes some patients to develop this complication. Studies have demonstrated degenerative changes within the olfactory epithelium, the severity of which seems to correlate with the severity of olfactory loss. Although no available therapy has proved effective, long-term follow-up data have found that approximately two thirds of these patients eventually experience a significant improvement in their olfactory function.
Most patients who present to an otorhinolaryngology clinic with facial pain and headaches believe they have sinusitis. There is an increasing awareness that neurologic causes are responsible for a large proportion of patients with headache and facial pain. If facial pain and pressure is the primary symptom, it is unlikely to be caused by sinus disease in the absence of any nasal symptoms or signs. Patients with facial pain who have no objective evidence of sinus disease are unlikely to be helped by surgery. Most patients with pain caused by sinusitis respond to medical therapy.
The human nasal cavity contains multiple sensory and olfactory structures. The nasal mucosa with its complex innervation detects the danger substances in the air and stimulates the protective reflexes. Healthy olfactory mucosa allows for appreciation of pleasant aromas and food flavors. The olfactory nerve, in concert with the trigeminal nerve, serves as a main interpreter and modulator of chemosensory information. The anatomy of the olfactory neuroepithelium, which occupies only a small portion of the nasal mucosa, is generally well understood, while the presence and distribution of the sensory/tactile receptors in the mucosa of the nasal cavity is still a subject of controversy. The nasal vestibule, lined with skin, contains receptors that can sense noxious stimuli and air-flow. The sensitivity of the nasal mucosa to air-flow still needs further research. Understanding the distribution of the air-flow receptors could help to guide nasal surgery for obstruction.
OBJECTIVES: Olfactory cleft disease was defined as (1) an olfactory disability related with a clinical and/or radiologic abnormality of the olfactory cleft and (2) a pathologic process limited to or predominating in the olfactory cleft. The objectives of this study were to describe the clinical and radiologic findings of this entity and to report the effect of medical therapy on the sense of smell. STUDY DESIGN AND SETTING: Thirteen patients with the criteria of olfactory cleft disease were included in this retrospective study. All patients had bilateral olfactory cleft abnormalities. A complete ENT examination with endoscopic evaluation and a computed tomography scan were performed in all cases. An olfactory threshold test was available in 12 cases before and after medical therapy, which included oral and topically administered steroid therapy. RESULTS: Olfactory disability was the major symptom of olfactory cleft disease. Other symptoms of chronic rhinosinus dysfunction was present in 75% of cases. Three pathologic processes were identified in patients with olfactory cleft disease: malformative, inflammatory, and inflammatory associated with anatomical deformities of olfactory cleft boundaries. Medical therapy was effective in lowering olfactory thresholds in 25% of the cases. CONCLUSIONS AND SIGNIFICANCE: Olfactory cleft disease involves various pathophysiologic processes. Computed tomography scanning provides the most information for diagnosis. Indications of functional endoscopic surgery remain to be defined after failure of medical therapy.
The olfactory bulb expresses one of the highest levels of insulin found in the brain. A high level of expression of the concomitant insulin receptor (IR) kinase is also retained in this brain region, even in the adult. We have previously demonstrated in a heterologous system that insulin modulates the voltage-dependent potassium channel, Kv1.3, through tyrosine phosphorylation of three key residues in the amino and carboxyl terminus of the channel protein. Phosphorylation also induces current suppression of the Kv1.3-contributed current in cultured olfactory bulb neurons (OBNs) of rodents. In order to explore the behavioral importance of this kinase-induced modulation of the channel for the olfactory ability of the animal, mice with a targeted-gene deletion of the insulin receptor were electrophysiologically and behaviorally characterized. Mice heterozygous for the insulin receptor kinase (IR+/-) gene performed the same as wild-type (+/+) mice when challenged with a traditional, non-learning-based task to test gross anosmia. There was also no significant difference across the two genotypes in tests designed to measure exploratory behavior or in a battery of systems physiology experiments designed to assess metabolic energy usage (locomotion, ingestive behaviors, weight, oxygen consumption, and respiratory quotient). Object memory recognition tests suggest that IR+/- mice have an impairment in recognition of familiarized objects; IR+/- mice demonstrate poor performance for both short-term (1 h) and long-term (24 h) memory tests in comparison to that of wild-type mice. Electrophysiological experiments indicate that mitral cell neurons cultured from both heterozygous and homozygous-null mice (IR+/- and IR-/-) have an decreased peak current amplitude compared with that recorded for wild-type (+/+) animals matched for days in vitro (DIV). These data indicate that the loss of one allele of the IR kinase gene modifies the electrical phenotype of the mitral cell neurons in the olfactory bulb without a change in gross olfactory ability. Given our findings that there are no significant changes in metabolic balance of the IR (+/-) mice but some impairment in memory retention, future experiments testing for specific olfactory behaviors or functional deficits in IR-/+ mice models of diabetes will need to either be tasks that do not require learning or will require a different model (such as diet-induced diabetes) that may evoke a stronger phenotype.
There is some evidence for an unusual body odour in schizophrenia that has been linked to a hexenoic acid derivative (trans-3-methyl-2-hexenoic acid; MHA). Poor body odour has been linked to increased negative symptoms and reduced olfactory identification ability. However, the relationship between these findings and MHA, including olfactory sensitivity for MHA, has not been examined. Olfactory sensitivity thresholds were assessed for MHA and n-butyl-alcohol (NBA), in normal controls (CTL; n=24), patients with chronic schizophrenia (CHR; n=32) and a first-episode psychosis cohort (FE; n=31). In addition, forced choice detection of the pheromonal steroids 5-alpha-androst-16-en-3-one, androsterone-sulphate and estrone-3-sulphate was performed along with a measure of olfactory identification. CHR patients had significantly reduced sensitivity to MHA, but not NBA, compared to FE and CTL subjects. While sensitivity to pheromones was not different between the groups, CHR patients who could not detect them also showed poorer sensitivity to MHA. Further, the CHR group showed a significant association between reduced MHA sensitivity and greater levels of disorganised and negative symptoms. No relationships between identification and sensitivity for any substance were found. Our findings are the first to report reduced sensitivity for MHA in chronic schizophrenia patients, in the absence of similar impairment for more traditionally used substances. This may be linked to olfactory habituation effects, abnormal chemical processing or a genetic predisposition.
BACKGROUND AND PURPOSE: Changes in olfactory function have been reported in patients receiving significant doses of radiation to the olfactory epithelium. Aim of this study was to investigate severity and time course of changes in olfactory function in patients irradiated for tumours of the head and neck region. MATERIAL AND METHODS: Forty-four patients receiving radiotherapy (RT) for tumours in the area of the head and neck participated (16 women, 28 men; age 11-81 y; mean 55 y). Olfactory function was measured before and bi-weekly during RT for 6 weeks. A subgroup (25 patients) was followed for 12 months. Patients were divided into two groups according to the dose to the olfactory epithelium. Twenty-two patients ('OLF group') had radiation doses to the olfactory epithelium between 23.7 and 79.5 Gy (median 62.2 Gy). In the 22 patients of the 'non-OLF group' the dose applied to the olfactory epithelium was significantly lower (2.9-11.1 Gy, median 5.9 Gy). Total tumour dose (30-76.8 Gy), age, sex distribution, and baseline chemosensory function were not significantly different between groups. Testing was performed for odour identification, odour discrimination, and olfactory thresholds. RESULTS: Odour discrimination, but not odour identification or odour threshold, was significantly decreased 2-6 weeks after begin of therapy in the OLF group. In addition, a significant effect of the radiation dose was observed for odour discrimination. More than 6 months after therapy, OLF group patients had significantly lower odour identification scores compared to the non-OLF group. CONCLUSION: As indicated through the non-significant change of olfactory thresholds, the olfactory epithelium is relatively resistant against effects of radiation. It is hypothesized that RT has additional effects on the olfactory bulb/orbitofrontal cortex responsible for the observed changes of suprathreshold olfactory function.
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OBJECTIVE: Olfactory deficits in schizophrenia patients have been suggested to reflect medial temporal and/or prefrontal brain abnormalities. In this study, we examined the relationship between different olfactory functions and volumes of the hippocampus-amygdala complex (HAC) and the orbitofrontal brain region using magnetic resonance imaging (MRI). METHODS: Thirty-three young men with schizophrenia (DSM-IV) and 40 healthy controls performed unirhinal olfactory assessment including the main olfactory functions (threshold, discrimination, and identification), and odor judgements (intensity, edibility, familiarity, and pleasantness). Volumes of regions in the medial temporal lobe (hippocampus and amygdala) and the prefrontal region (orbitofrontal gray and white matter) were measured on MRI scans. RESULTS: Compared with controls, patients showed bilaterally impaired thresholds, quality discrimination and identification, as well as edibility judgements. Olfactory deficits were not attributable to smoking, premorbid intelligence, or impaired thresholds. Relative to controls, patients had bilateral reduced hippocampus and amygdala volumes. In patients, smaller hippocampus volumes were associated with poorer olfactory discrimination ability. CONCLUSIONS: Olfactory deficits in schizophrenia appear to be associated with morphometric abnormalities in the medial temporal rather than the orbitofrontal region (OFR). These results indicate that olfactory quality discrimination deficits are related to structural hippocampus abnormalities. Future studies of genetic and behavioral high-risk samples seem warranted.
OBJECTIVE: To assess mucociliary transport and olfaction in patients after Le Fort fractures. STUDY DESIGN: Forty-one patients were enrolled who had sustained a Le Fort fracture during the preceding five years. Control group consisted of students. Olfaction and mucociliary transport were examined in all subjects. A capillary with saccharine was placed on the inferior nasal concha, and time was recorded in which the subject tasted sweetness in the mouth. Results were subject to statistical analysis. Patients with allergy, sinus disease and smokers were excluded from the examination. RESULTS: Disturbance of mucociliary transport and olfaction turned out to be statistically dependent on the type of fracture and management. CONCLUSIONS: Le Fort fracture might be complicated by compromised mucociliary clearance and olfactory disturbances.
OBJECTIVE: To create a screening olfactory test based on the CCCRC (Connecticut Chemosen-sory Clinical Research Center). MATERIAL AND METHODS: We compare the screening test based on CCCRC with PST (Pocket Smell Test) based on UPSIT in 40 patients with nasal poliposis, in order to de-termine the specificity, sensitivity, positive predictive and negative predictive value. The validity index was 95% and accuracy rate was 10%. We determine unit cost, the time required to perform the test in outpatients office and how difficult it is to do the test. RESULTS: Sensibility was 88%, specificity was 77%. The positive predictive value was 34% and the negative predictive value was 94%. The unitary cost of our screening test was 0.57 euros when it is performed by a nurse. The unitary cost of PST is 1.76 euros. To perform our screening test took 2.8 +/- 0.4 minutes. The 96% of the patients thought the test was easy to do. CONCLUSION: Our test is a valid screening test to be used in patients with nasal poliposis.
The ability to smell is commonly altered by head injuries. However, the nature, prevalence, prognosis and etiology of such alterations are poorly understood. Patients complaining of head-trauma and a related olfactory dysfunction typically have anosmia and rarely regain normal olfactory ability. Parosmia prevalences decreases over time in such patients, and damage to olfaction-related brain structures can be observed in most such patients using an appropriate MRI protocol. In this article, we review the recent knowledge about postraumatic anosmia.
BACKGROUND: To study and evaluate the factors that may influence on human olfactory sensibility to pyridine, we designed a specific laboratory with a new olfactory test to perform accurate measurements. METHODS: We have chosen pyridine as the test substance in our laboratory, for its frequent use of it in other studies. The special conditions of our laboratory are designed to allow individuals to access to this substance, controlling the different factors and parameters. With this purpose, we have validated the test and we have settled the reference threshold values with the score of thirty voluntary healthy patients between 20 and 40 years of age. RESULTS: We have used four different concentrations of pyridine to study the different factors of olfactory sensibility. 95% of cases detected the highest pyridine concentration and the remaining concentrations allowed us to know the olfactory sensibility of the studied population and the inferior thresholds. CONCLUSIONS: We have designed, performed and endorsed a laboratory for the study of olfaction. We have determined the sensibility of the studied population to different concentrations of pyridine that can be considered as a reference for further studies.
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OBJECTIVE/DESIGN: To determine the nutritional risk associated with measured olfactory dysfunction in free-living, elderly women through analytic observational methods. Olfactory perception was measured orthonasally (odor: butanol threshold and odor identification) and retronasally (flavor: orange flavor threshold in sweetened gelatin). SETTING/SUBJECTS: Elderly women were recruited from New Haven, Conn, through posters and direct contact. Screening of 120 elderly women identified 80 with high personal functioning to participate (mean age = 76 +/- 6 years, range = 65 to 93 years). All data were collected in subjects' homes. MAIN OUTCOME MEASURES: Nutritional risk was assessed in several ways: food behavior questionnaire; food preference questionnaire; interviews based on the National Cancer Institute food frequency questionnaire; five nonconsecutive, 24-hour food records; and weight, height, waist, and hip measurements. STATISTICAL ANALYSES: Correlation and regression analyses determined the separate association between olfactory perception and nutrition variables. RESULTS: Nearly half of the women (37 of 80) had olfactory dysfunction. The following nutritional risk pattern was associated with lower olfactory perception: lower interest in food-related activities (eg, enjoying cooking, eating a wide variety of foods); lower preference for foods with predominant sour/bitter taste (eg, citrus fruits) or pungency (eg, horseradish); higher intake of sweets; less intake of low-fat milk products; and nutrient intake profile indicative of higher risk for cardiac disease. APPLICATIONS: Olfactory dysfunction may make it more difficult for elderly women to maintain a diet to control risk for chronic disease. Practitioners should target nutrition intervention to elderly women with measured or self rated difficulty in preventing odors or olfactory flavor. Capitalizing on primary-taste quality and texture may help to compensate for the loss of olfactory flavor perception.
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