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PubMedDate not supplied

Mapping brain activation to odorants in patients with smell loss by functional MRI.

PURPOSE: Our goal was to use functional MRI (fMRI) to develop an objective, noninvasive technique by which patients with smell loss can be identified, their abnormalities quantitated, their results compared with findings in normal subjects, and visual representation of their CNS pathology obtained. METHOD: Functional MR brain scans were obtained in eight patients with hyposmia in response to three olfactory stimuli (pyridine, menthone, amyl acetate) in three coronal brain sections selected from anterior to posterior temporal brain regions using multislice FLASH MRI. Results were compared with similar studies performed in 17 normal subjects. Activation images were derived using correlation analysis, and ratios of area of brain activated to total brain area were obtained. RESULTS: Brain activation to each stimulus was lower in each section in patients compared with normal subjects and reached statistical significance for mean activation for each odor and in six of the nine individual sections studied. Activation in patients was found in regions previously associated with CNS processing of olfactory stimuli in normal subjects, but activation in patients was much less, particularly in inferior frontal and cingulate gyral regions of frontal cortex and in regions of medial and posterior temporal cortex. CONCLUSION: These results demonstrate quantitative CNS changes in smell function in response to olfactory stimuli in patients with hyposmia, demonstrate a novel, objective method by which these patients can be identified, and provide maps of the CNS changes associated with their smell loss.

Adult↗
PubMed2004

Smell testing: an additional tool for identification of adult Refsum's disease.

BACKGROUND: Adult Refsum's disease (ARD) is characterised by the presence of retinitis pigmentosa, ataxia, deafness, sensory neuropathy, and bony changes. The diagnosis is confirmed by the presence of phytanic acidaemia. Although reduced smell function has been described in ARD, its value in the diagnosis of the condition has not been fully evaluated. OBJECTIVE: To investigate the prevalence and degree of olfactory dysfunction in patients with ARD. METHOD: The olfactory function of 16 patients with ARD was assessed using the quantitative University of Pennsylvania Smell Identification Test (UPSIT). RESULTS: All patients had complete anosmia or grossly impaired smell function with a mean UPSIT score of 14.7 (SD 4.7) (normal > 34) despite having been treated with an appropriate diet for a median of 15 years (range 1-25). CONCLUSIONS: Identification of ARD patients can be facilitated by using the UPSIT in combination with the presence of retinitis pigmentosa, even if they have no neurological or bony features. Phytanic acid screening should be performed in any patient manifesting these two signs.

Adolescent↗
PubMed1974

Abnormalities of taste and smell after head trauma.

Abnormalities of taste and smell were studied in 29 patients after head trauma. These abnormalities included decreased taste acuity (hypogeusia), a distortion of taste acuity (dysgeusia), decreased smell acuity (hyposmia), and a distortion of smell acuity (dysosmia). This syndrome can occur even after minimal head trauma and can begin months after the moment of injury. The patients exhibited a significant decrease in total serum zinc concentration (patients, 77 ± 3 μg/100 ml, mean ± 1 SEM, vs controls, 99 ± 2 μg/100 ml, P>0·001) and a significant increase in total serum copper concentrations (113 ± 4 μg/100 ml vs 100 ± 2 μg/100 ml, P<0·001) compared with control subjects. Symptoms of hypogeusia, dysgeusia, and dysosmia are frequent sequelae of head injury and are important to the patients and to their care after trauma.

Adult↗
PubMed2001

Smelling in color: a rainbow of possibilities.

A sensor that detects dangerous odors better than the human nose may be able to "smell" dangerous air pollutants, soil contaminants, insecticides, food pathogens, biological warfare neurotoxins, and body odors associated with illness and disease. Called "smell-seeing" by its inventors, the method relies on color changes that occur in an array of vapor-sensitive dyes in response to exposure. By measuring the color change pattern, the researchers can identify a contaminant both qualitatively and quantitatively. This newest version of an artificial nose is simple, fast, and inexpensive. It can also eliminate the subjectivity associated with the human sense of smell and the perception of odors.

Air Pollutants↗
PubMed1994

[The activity of superoxide dismutase in patients with taste and smell dysfunction].

It was revealed that Zinc deficiency might cause taste and smell dysfunction. Superoxide dismutase (SOD), which scavenges superoxide, is a type of zinc enzyme. It was also demonstrated that the overproduction of superoxide damages normal tissue. We therefore measured the activity of SOD in serum and saliva of patients with taste or smell dysfunction by the cytochrome C reduction method using a xanthine-xanthine oxidase system. As a result, in the patients with taste dysfunction, the activities of SOD in both serum and saliva were normal, but mean level of serum Zinc was near to the lower normal limit. On the other hand, in the patients with smell dysfunction caused by chronic sinusitis or common cold, the activity of SOD in serum was significantly lower than that of healthy volunteers, and that in saliva was normal. These results suggest that Zinc enzymes, except serum and salivary SOD, are involved in the sense of taste, and that further investigation is necessary to clarify the relation between serum SOD deficiency and olfactory dysfunction.

Adult↗
PubMed1990

[A pragmatic assessment of sense of smell].

A new clinical odour test was developed and validated in a clinical trial including 50 healthy volunteers as well as 35 patients suffering from smell disorders. The aromas were incorporated in an inert gas under disclosure from oxygen, avoiding impairment caused by oxidative transformation. Conventional smell test by Elsberg bottles was used as standard. The spray test proved to be equally effective in discriminating subjects suffering from smell disorders as the standard procedure. Moreover the spray test is feasible and long term constance of the substances is guaranteed.

Aerosols↗
PubMed1991

Electrical taste detection thresholds and chemical smell detection thresholds in patients with cancer.

Taste sensation in patients with cancer has previously been studied with the cumbersome method of chemical gustometry, which have produced inconsistent results. In this study taste thresholds were determined with the simple and reliable technique of electrogustometry in 51 patients with cancers of the lung (small cell), ovary or breast, and in 29 matched control patients with nonneoplastic disease. Chemical smell thresholds for phenyl-methyl-ethyl-carbinol were studied in the same group of patients. Electrical taste threshold was higher in patients with cancer compared with control patients (30 [12 to 80] microA versus 9.5 [6.1 to 24] microA; median [interquartile range], P less than 0.001). No differences were seen in smell thresholds. Patients who responded to chemotherapy obtained a decreased electrogustometric threshold at time of reevaluation (24 [8 to 64] microA versus 30 [15 to 90] microA; median [interquartile range], P less than 0.05). These results suggest an effect of the malignant disease itself on taste thresholds.

Adult↗
PubMed2005

A 10-item smell identification scale related to risk for Alzheimer's disease.

University of Pennsylvania Smell Identification Test data from control subjects (n = 63), patients with mild cognitive impairment (n = 147), and patients with Alzheimer's disease (n = 100) were analyzed to derive an optimal subset of items related to risk for Alzheimer's disease (ie, healthy through mild cognitive impairment to early and moderate disease stages). The derived 10-item scale performed comparably with the University of Pennsylvania Smell Identification Test in classifying subjects, and it strongly predicted conversion to Alzheimer's disease on follow-up evaluation in patients with mild cognitive impairment. Independent replication is needed to validate these findings.

Aged↗
PubMed2004

Smell identification test as an indicator for cognitive impairment in Alzheimer's disease.

OBJECTIVES: The aim of the present study was to assess olfactory dysfunction in patients with Alzheimer's disease (AD) and to compare utility of the olfactory tests as possible clinical markers. METHODS: Two olfactory identification tests (The Cross-Cultural Smell Identification Test [CC-SIT] and the Picture-based Smell Identification Test [P-SIT]) and the Mini Mental State Examination (MMSE) were administered to patients with AD and age-matched controls. Apolipoprotein E (Apo E) genotypes of patients with AD were identified. RESULTS: Patients with AD had significantly lower olfactory identification scores than age-matched non-demented elderly subjects in both olfactory assessments. In the AD group, the coefficient of correlation between the MMSE scores and the P-SIT scores was higher than that between the MMSE scores and the CC-SIT scores. Receiver operating curve (ROC) analyses for both tests indicated that the P-SIT discriminated AD patients from controls more reliably than did the CC-SIT. Within AD patients, those who were carrying one or two ApoE epsilon4 alleles had a higher coefficient of correlation between the MMSE scores and the P-SIT scores than patients without the ApoE epsilon4 allele. CONCLUSIONS: The results suggest that a short and simple non-lexical olfactory identification test can be useful as a clinical marker of AD appropriate for Japanese elderly population.

Aged↗
PubMed1975

[Evaluating function and disorders of smell].

Firstly the review deals with the olfactometry after discussing the olfactory and trigeminal sensitivity of the sense of smell. The term olfactometry will be newly fixed concerning the present problems of odor analysis. Under clinical aspects the methods of subjective olfactometry are discussed and valued. Olfactory tests basing on registering several psychosomatic reflexes (e.g. cardial and/or respiratory frequencies) cannot be described as "objective". Rather methods are objective which record poststimulatory electrophysiological events at different steps of olfactory pathways. The electric response olfactometry representing a cortical evoked so-called twin-potential containing equivalents for trigeminal and olfactory sense activity starts to demonstrate its efficiency. At least a complete test of olfactory function today includes the rhinomanometry for recording ability in nasal odor transport capacity. In the second part are discussed the olfactory disorders with clinical importance. Air borne disorders are confronted with sensorineural, which again are divided in prebulbar, bulbar, and postbulbar ones so far as possible. Respiratory smell disorders depend on nasal ventilation and occur in nasal deformations, in abnormalities of respiratory pathways, in cases of foreign bodies, mucosal inflammations, tumors, intoxications and allergy. Sensorineural olfactory disorders can be attached to age, to malformations or idiopathic defects, inflammations of the olfactory-neural apparatus, head injuries, brain tumors, metabolic or endocrinological diseases. Furthermore often they are accompanied with neurological and psychiatric diseases or professional and chemical intoxications and/or iatrogenic influences. The poor therapeutical possibilities are demonstrated as far as possible. Finally the experting problems in olfactory disorders are delineated, at which the evidence of objective olfactometry can be distincted.

Animals↗
PubMed1983

The effect of right temporal lobe lesions on matching of smells.

Thirty patients with bitemporal lobe epilepsy, 14 patients with right temporal lobe epilepsy, 14 patients with left temporal lobe epilepsy, 14 patients who had right temporal lobectomy, 10 patients who had left temporal lobectomy and 12 patients who had lobectomy involving frontal or fronto-parietal regions were tested for their ability to match smells. A simple matching technique was used. It was found that patients with right temporal lobe lesions had difficulty in matching smells. There was no significant difference between the right temporal lobe epilepsy group and the right temporal lobectomy group. The implications of these findings are discussed.

Discrimination Learning↗
PubMed1989

A theoretical model for perceived intensity in human taste and smell. II. Temporal integration and reaction times.

The theoretical model for perceived intensity in human taste and smell published previously was extended by incorporating the concept of signal detectability and temporal integration phenomena at low and high stimulus levels. The processes involved in human taste and smell perception are divided into three stages: a) An "internal meter" registers outside signals. Adaptation occurs at this stage. b) The meter is read for two possible purposes: to detect a weak signal or to estimate the signal's intensity. Both tasks require the smoothing of noise, which is accomplished by integration of the meter over time. c) The internal estimate is expressed through the use of a scaling method.

Humans↗
PubMed1995

Performance on a smell screening test (the MODSIT): a study of 510 predominantly illiterate Chinese subjects.

The 12-item Modular Smell Identification Test (MODSIT) was administered to 239 male and 271 female Chinese subjects whose age ranged from 50 to 92 years (68.3 +/- 10.9) and whose education ranged from 0 to 20 years (2.5 +/- 4.3). Every participant was examined by a physician and was found to be free of dementia, stroke, and Parkinson's disease. Different from the standard procedures, only one-third of each odor pad was used for each subject, the four odor choices were presented orally for the majority of subjects, and they were not forced to make a selection when they could not detect or identify the odor. The average level of performance was 46% correct. The score was negatively associated with age, positively associated with education and with performance on a dementia screening test, and corroborated with subjects' report of smell deterioration in recent years. Nonsmokers and women performed better than smokers and men. The 12-item MODSIT had an internal consistency reliability of 0.73 and a 7-month retest stability of 0.57 with different examiners. The MODSIT is satisfactory for group studies, even when administered with suboptimal procedures such as those used in the present study.

Age Distribution↗
PubMed2005

How do children with adenoid hypertrophy smell and taste? Clinical assessment of olfactory function pre- and post-adenoidectomy.

OBJECTIVE: To assess the ability to smell and appreciate food in children with adenoid hypertrophy pre and post-adenoidectomy. METHODS: A total of 35 children with adenoid hypertrophy admitted for adenoidectomy (aged 5-9.3 years, mean age 5.9 years) were tested preoperatively. In a follow up appointment 3 months postoperatively, 28 of them returned and were tested again. The control group consisted of 30 healthy children (aged 5-10.2 years, mean age 6.1 years). Orthonasal olfactory function was assessed psychophysically using "Sniffin sticks" 12 item odor identification test. Retronasal olfaction was assessed using a collection of 12 grocery available powders applied to the oral cavity. RESULTS: Both orthonasal and retronasal olfactory function of the study group preoperatively were significantly lower in comparison with the results of the control group (p<0.0001). The difference in retronasal olfaction between groups was significantly higher in comparison with the difference in orthonasal odor identification (p=0.048). There is a strong correlation between adenoid hypertrophy grade and retronasal testing results (t=-5.461, p<0.0001), but not with the orthonasal results (t=-1.677, p=0.9). Significant improvement of orthonasal and retronasal olfaction was observed in the follow-up appointment (p<0.0001). Relative increase postoperatively was higher for the retronasal olfaction compared to orthonasal olfaction (p=0.0029). CONCLUSIONS: Children with adenoid hypertrophy have a reduced ability to smell, with retronasal olfactory function being more affected. Surgery had a greater impact on retronasal olfaction.

Adenoidectomy↗
PubMed2004

Smell testing is abnormal in 'lubag' or X-linked dystonia-parkinsonism: a pilot study.

We administered a culturally corrected University of Pennsylvania Smell Identification Test (ccUPSIT) consisting of 25 odor items to 20 patients with 'Lubag' or X-linked dystonia-parkinsonism and 20 control subjects matched by sex, age, educational background, smoking history, and geographical origin. The mean ccUPSIT score of Lubag patients (18 +/- 3.19) was statistically lower (P = 0.003) than controls (20.5 +/- 3.02). The smell scores did not correlate with phenotype, severity of dystonia, or duration of disease. Nine of 20 Lubag patients (45%) had ccUPSIT scores below the mean, with the lowest score being 11. This pilot study suggests that olfactory dysfunction may occur in Lubag patients.

Adult↗
PubMed2005

Prevalence of annoyance attributed to electrical equipment and smells in a Swedish population, and relationship with subjective health and daily functioning.

BACKGROUND: Self-reported annoyance from electrical equipment has been in evidence since the mid-1980s, and the first reports of illness from everyday chemicals arose in the 1960s. However, the extent of the problem has not yet been fully established. AIMS: The aim of this study was to estimate the prevalence of annoyance related to electrical and chemical factors in a Swedish general population, and to assess possible relationships with subjective health and daily functioning. METHODS: In total, 13,604 subjects, representative of the population of Scania, Sweden, answered a survey containing five questions regarding annoyance from five environmental factors: fluorescent tube lighting, visual display units, other electrical equipment, air that smells of chemicals, and other smells. The survey also obtained data on self-reported health (SRH-7), mental well-being [General Health Questionnaire (GHQ)-12], work situation and daily functioning. RESULTS: Almost one-third of the respondents reported annoyance from at least one environmental factor. Annoyance was more frequent among women, subjects of working age and immigrants. Subjects who reported environmental annoyance scored higher on GHQ-12 and lower on SRH-7, indicating impaired subjective physical and mental well-being. They were also more likely to report deteriorated daily functioning. CONCLUSIONS: Annoyance related to electrical and/or chemical factors was common in a Swedish population. Subjects reporting environmental annoyance rated their overall health significantly poorer than the general population. The association with subjective health and functional capacity increased with severity of annoyance, which suggests that there is some connection between environmental annoyance, well-being and functional capacity.

Adult↗
PubMed1997

Sniffing behaviour, or recognizing a lily by smell, but not recognizing a sock on sight.

We report a 65-year-old man with a post-anoxic encephalopathy who showed compulsive sniffing at available objects. This stereotyped environment-driven behaviour has not been previously described. Other compulsive environment-driven responses, such as manipulation and utilization of tools and hyperlexia, were also present. The disorder shared several features with the Klüver-Bucy syndrome where mouthing of objects, rather than smelling them, is common. The patient had a severe dementia, with amnesia, anomia, apraxia, and visual agnosia. Whereas he could not recognize very familiar objects on sight, he could in contrast correctly identify several familiar odours. Although sniffing was a compulsive and purposeless environment-driven behaviour, the question may be asked whether a relatively preserved olfactory recognition, in the presence of a severe disorder of visual recognition and knowledge, could have favoured a stereotyped exploration of objects by smelling.

Aged↗
PubMed2001

Smelling of odorous sex hormone-like compounds causes sex-differentiated hypothalamic activations in humans.

The anatomical pathways for processing of odorous stimuli include the olfactory nerve projection to the olfactory bulb, the trigeminal nerve projection to somatosensory and insular cortex, and the projection from the accessory olfactory bulb to the hypothalamus. In the majority of tetrapods, the sex-specific effects of pheromones on reproductive behavior is mediated via the hypothalamic projection. However, the existence of this projection in humans has been regarded as improbable because humans lack a discernable accessory olfactory bulb. Here, we show that women smelling an androgen-like compound activate the hypothalamus, with the center of gravity in the preoptic and ventromedial nuclei. Men, in contrast, activate the hypothalamus (center of gravity in paraventricular and dorsomedial nuclei) when smelling an estrogen-like substance. This sex-dissociated hypothalamic activation suggests a potential physiological substrate for a sex-differentiated behavioral response in humans.

Adult↗