Clinical assessment of retronasal olfactory function

OBJECTIVES: To develop a test kit for the simple assessment of retronasal olfactory function and to compare orthonasal and retronasal olfactory function in healthy subjects and patients with olfactory disorders. DESIGN AND PATIENTS: We tested 230 individuals with normosmia, hyposmia, and anosmia using grocery-available powders. Initially, 30 different substances were investigated. Subjects identified each substance using a list with 4 verbal items (forced choice). After preliminary experiments, 20 items were selected according to the degree to which they were identified by normosmic and anosmic subjects. Orthonasal olfactory function was assessed psychophysically using "sniffin' sticks," which includes tests for odor identification, discrimination, and butanol odor thresholds. In addition, anosmia was confirmed electrophysiologically by means of olfactory-evoked potentials. RESULTS: In healthy subjects, there was a test-retest reliability correlation of r(27) = 0.76 for retronasal olfactory function, which is similar to other odor identification tests. Retronasal testing in normosmic subjects allowed for the discrimination of sex-related differences, with women scoring higher than men (P =.007), and the identification of a slight decrease with age (r(120) = -0.20; P =.03). Orthonasal and retronasal identification of odors was found to correlate (r(86) = 0.78; P<.001). Retronasal testing allowed for the discrimination between normosmia, hyposmia, and anosmia (P<.001). In addition, retronasal performance of anosmic patients appeared to improve with duration of anosmia (P =.03). No difference was found between patients with anosmia of different origin. CONCLUSION: Results of the present investigation indicate that the assessment of retronasal olfactory function is possible using oral stimulus presentation.     

Electro-olfactogram (EOG) in olfactometry

The electro-olfactogram (EOG) is a potential originated in olfactory epithelium evoked by odorous stimulation, which has been demonstrated and termed by Ottoson (1959). In order to ascertain the clinical application of EOG, we attempted to record similar potentials in human subjects. In some preliminary experiments using rabbits, it was quite easy to produce Ottoson's findings. In human subjects, however, there were sometimes great technical difficulties owing to the hidden anatomical position of the olfactory epithelium. Then we utilized Olympus selfoscope endoscopy for placing and retaining the electrode to the olfactory portion precisely and safely, with a tube for sending airborne odor. As results, we succeeded in recording negative spike discharge similar to Ottoson's findings. We examined a total of 27 nasal cavities in 22 patients with peripheral olfactory disorders and 11 nasal cavities in 12 patients with central olfactory disorders. The positive EOG rate in patients with peripheral or central olfactory disorders was 28 and 69%, respectively. Moreover, the positive rate was decreased in proportion to the degree of olfactory disorders in chronic rhinosinusitis. No positive EOG was observed in anosmic nasal cavities, while it was 68% in normal persons and resulted in an equal value to anosmia group caused by the damage of central olfactory pathway. From these results, it is considered that the positive EOG study is the only method which provides objective finding for the differential diagnosis of anosmia caused by disorders of olfactory epithelium or disorders of central olfactory tract.     

Can we smell without an olfactory bulb?

BACKGROUND: Lack of an olfactory bulb (OB) is typically associated with anosmia. METHODS: We present a patient with subnormal olfactory function in whom the OB could not be detected with magnetic resonance imaging (MRI). RESULTS: Olfactory function was evaluated on two occasions. Orthonasal olfactory function was assessed with the "Sniffin' Sticks" test providing a score equivalent to hyposmia. Retronasal olfactory function was studied with "smell powders" indicating a decreased, but not absence of, olfactory function. Importantly, chemosensory event-related potentials were clearly present in response to olfactory and trigeminal stimuli. CONCLUSION: This indicates that olfactory function may be present in some subjects even when an OB can not be detected with MRI.     

外伤后失嗅患者的嗅觉事件相关电位和MRI评估

目的 探讨嗅觉事件相关电位(olfactory event related potentials,OERP)和嗅觉通路MRI对外伤后失嗅的评估价值.方法 回顾性分析24例外伤后失嗅患者的临床资料.所有患者均行详细的病史采集、全面体检、T&T嗅觉检查、鼻内镜检查、OERP测试、颅脑CT和嗅觉通路MRI检查.结果 主观嗅觉测试:双侧完全失嗅20例;单侧完全失嗅,对侧嗅觉减退2例;单侧完全失嗅,对侧嗅觉正常2例.OERP测试:双侧最大嗅刺激均不能引出OERP者20例,单侧最大嗅刺激不能引出OERP者4例;单侧能引出OERP者4例,其中2例能正常引出,另2例OERP幅值下降且潜伏期延长.氨气刺激均能引出鼻内三叉神经化学感受事件相关电位.嗅路MRI检查:嗅球损伤24例次(100%),额叶直回损伤22例次(91.7%),额叶眶回损伤16例次(67%),远端嗅束和颞叶损伤各2例次(8%).结论 OERP能对外伤后嗅觉进行定性和定量的客观整体评估;嗅路MRI能对外伤后失嗅的损伤部位、程度进行客观、精确的评估.两者结合能对嗅觉功能进行全面、客观评价.     

Screening of olfactory function using odourized markers

BACKGROUND: The goal of our study was to create a psychophysical test for the screening of olfactory function on the basis of commercially available odourized markers (OM). There are six coloured markers in one package filled with different odourants at suprathreshold levels. In order to identify the best approach, we investigated five different variations of the technique. MATERIALS AND METHODS: Olfaction was investigated in 189 subjects. Healthy participants as well as patients suffering from olfactory disorders were tested. Initially subjects were tested by one of five methods using OM. Finally, the "Sniffin' Sticks" test (butanol odour threshold, odour identification) was performed. RESULTS: Correlation of the OM screening test and the "Sniffin' Sticks" ranged from 0.49 to 0.93 indicating that variations of the technique strongly influence the results of testing. The best technique for evaluating olfactory function included spontaneous naming of odours and odour identification from a list of four distractors. The sensitivity of this method was sufficient to determine anosmia. CONCLUSIONS: The odourized markers screening test can be used to screen for anosmia in the general population. However, the precise quantification of olfactory function is not possible, because of the relatively small amount of odours.     

Anosmia after intranasal zinc gluconate use

BACKGROUND: Zinc is an essential mineral. Beneficial zinc absorption takes place via enteral, parenteral, or cutaneous routes. However, direct application to the olfactory epithelium has been reported to cause loss of smell. Recently, intranasal zinc gluconate has been recommended as a treatment for the common cold. Severe posttreatment hyposmia and anosmia have been observed. METHODS: The case report of a typical patient is presented and analyzed in detail, followed by a series of patients with severe hyposmia or anosmia after the use of intranasal zinc gluconate. RESULTS: Although interindividual variation in drug response and drug effect is apparent, the severe hyposmia or anosmia appears to be long lasting or permanent in some cases. The mechanism of olfactory loss is thought to be the direct action of the divalent zinc ion on the olfactory receptor cell. CONCLUSIONS: Zinc ions are toxic to olfactory epithelium. Reports of severe hyposmia with parosmia or anosmia have occurred after intranasal use of zinc gluconate.     

先天性失嗅患者的临床研究

目的总结先天性失嗅的分类、临床表现以及影像学特点。方法回顾性分析2004年8月-2006年9月收治的8例先天性失嗅病例的临床资料。4例为伴有其他异常的先天性失嗅患者，其中卡尔曼综合征（Kallmann syndrome）3例，鼻腔鼻窦发育异常1例；另外4例为孤立性失嗅。8例患者均行详细的病史采集、全面体检、T＆T嗅觉检查、嗅觉事件相关电位测试、鼻内镜检查和鼻窦CT检查。7例行嗅觉通路MRI和性激素检测，2例行嗅黏膜活组织检查。结果8例患者自幼均未闻到过任何气味。除1例鼻腔鼻窦发育异常外，其余7例耳鼻咽喉科常规检查以及鼻内镜检查未见异常。主观嗅觉测试均为完全失嗅。嗅觉事件相关电位测试显示最大嗅刺激引不出嗅觉事件相关电位。CT检查显示1例鼻腔鼻窦未发育，其余7例未见异常。MRI检查：6例均为嗅球、嗅束缺失，嗅沟缺失或部分变浅；1例双侧嗅球发育差。内分泌检查：3例青春期后外生殖器以及男性第二性征发育不良，血清睾酮、雌二醇、促黄体生成素以及促卵泡生成素水平低于正常。其余4例性激素检测正常。嗅黏膜活检：1例未见嗅上皮典型结构；另1例为鳞状上皮组织伴慢性炎性病变。结论先天性失嗅诊断应依据病史、专科体检、嗅觉测试、鼻窦cT以及嗅路MRI检查结果。嗅路MRI对诊断有重要价值。     

Normal sense of smell in Kallmann syndrome. A case report

BACKGROUND: Kallmann's syndrome (KS) was first mentioned in 1944 as an association of anosmia and hypogonadotropic hypogonadism. Causes are multiple genetic defects the most common of which is the x-linked KS appearing mostly in men. However, autosomal dominant and autosomal recessive forms have also been described. PATIENT: We present a case of KS with normosmia (male, 39 years of age). All symptoms of hypogonadotropic hypogonadism were present. RESULTS: Psychophysical olfactory testing revealed left-sided anosmia with right-sided normosmia which was confirmed by electrophysiological measures of olfactory function. Magnetic resonance imaging indicated aplasia of the left olfactory tract and bulb, whereas the right-sided structures appeared to be normal. CONCLUSIONS: As indicated in this case with lateralized anosmia and contralateral normosmia, overall olfactory function strongly depends on the "best" nostril. Therefore, in many clinical situations, lateralized olfactory testing appears to be extremely important.     

嗅觉味觉功能的临床检测

目的:探讨嗅觉障碍患者嗅觉和味觉功能的改变。方法:284例受试者中,健康人92例,嗅觉功能减退92例,嗅觉功能丧失100例,分别采用T&T、嗅觉事件相关电位(OERPs)及三滴法进行嗅觉和味觉功能检测。结果:T&T结果,嗅觉功能减退和丧失患者跟健康人比较差异有统计学意义(P<0.05)。OERPs结果显示,嗅觉功能障碍患者跟健康人比较N1、P2波潜伏期延长且振幅降低,差异有统计学意义(P<0.05)。三滴法结果显示,嗅觉功能障碍患者跟健康人比较味觉功能有明显减退,差异有统计学意义(P<0.05)。各组之间男女比较差异无统计学意义。结论:嗅觉功能障碍患者同时伴有味觉功能的减退,嗅觉和味觉功能的减退与性别关联不大。嗅觉味觉的联合检查可以全面系统反映受试者的化学感觉功能,为临床诊断和治疗提供科学依据。     

Clinical significance of results from olfactory testing

BACKGROUND: Although widely used in healthy subjects and patients with olfactory loss, the significance of changes of scores from validated olfactory tests is unknown. AIM AND METHODS: The aim of the present study was to relate the self-assigned changes of olfactory function in terms of "better," "unchanged," and "worse" in patients with smell disorders with the results from olfactory testing by means of a validated test set. Olfactory function of 83 anosmic or hyposmic patients (40 women, 43 men; age 12-84 yr) was tested on two occasions (mean interval 136 days, minimum 7 days, maximum 6.7 yr). Olfactory function was assessed using a validated technique ("Sniffin' Sticks"). This test consists of three subtests, one for odor threshold (T), odor discrimination (D), and odor identification (I), with possible results ranging up to 16 points each. From the sum of the results from the three subtests a composite "TDI" score was obtained. RESULTS: Forty-four patients indicated an improvement of olfactory function, whereas 39 patients reported no change. No subject reported deterioration of olfactory sensitivity. Subjects assigned to group BETTER had higher TDI scores in the second olfactory tests than subjects assigned to the group UNCHANGED, both in absolute terms and as compared with the first olfactory test (effect "test occasion" by "self-assessed improvement," P < .001). There was no significant difference between groups with respect to age and sex (P = .99 and .84, respectively). Logistic regression showed that more than 60% of the subjects reported an improvement of olfactory sensitivity when the TDI score increased by 5.5 points. CONCLUSION: We show that there is a statistically significant relation between measured and perceived improvement of olfactory function in patients who first presented with the diagnosis of anosmia or hyposmia. The results indicate that improved olfactory function in patients with olfactory deficiency is perceived as such in everyday life and is quantitatively related to an improvement in the composite TDI score of the "Sniffin' Sticks" olfactory test battery. This is the basis for the application of a specific therapy for olfactory loss because of a possible gain in quality of life for the patients.     

Effect of ginkgo biloba and dexamethasone in the treatment of 3-methylindole-induced anosmia mouse model

BACKGROUND: Olfactory loss is a challenging disease. Although glucocorticoid is sometimes used for the treatment of anosmia, it has been reported that it potentiated neural damage in the early phase of treatment. This study is designed to identify the effect of ginkgo biloba, an antioxidant that acts as a free radical scavenger, in the treatment of olfactory injury aggravated by dexamethasone. METHODS: Anosmia mouse model was induced by i.p. injection of 3-methylindole (3-MI). Twenty-five mice were divided into one control group without anosmia and four anosmia treatment groups (given treatments of dexamethasone and/or ginkgo biloba). The effects of treatment were evaluated by behavioral test, Western blot, and immunohistochemistry 2 weeks after 3-MI injection. RESULTS: Induction of anosmia was confirmed by behavioral tests. The thickness and cell number of olfactory neuroepithelium were decreased more significantly in the dexamethasone treatment group than in the combination treatment group. The expression of olfactory marker protein (OMP) in olfactory epithelium was more decreased also in the dexamethasone treatment group than in the combination treatment group. The expression of OMP was decreased significantly in the olfactory bulbs of anosmia groups but there were no differences between the anosmia treatment groups. CONCLUSION: Dexamethasone treatment was associated with further deterioration of olfactory injury by 3-MI and it was recovered by combination treatment of dexamethasone and ginkgo biloba. The antioxidant effect of ginkgo biloba might play a role in restoration of olfactory loss and it was effective only when oxidative stress is maximized by dexamethasone.     

Alteraciones del olfato en la COVID-19, revisión de la evidencia e implicaciones en el manejo de la pandemia

There is debate as to whether olfactory dysfunction should be considered a symptom of COVID-19 infection. We undertook a systematic literature review of the articles indexed in PubMed on olfactory disorders in viral respiratory tract conditions, with special emphasis on COVID-19. The main objective was to find evidence of clinical interest to support the relationship between anosmia and COVID-19. Olfactory disorders in upper respiratory tract infections are frequent, most caused by obstruction due to oedema of the nasal mucosa. Occasionally, post-viral sensorineural olfactory dysfunction occurs, with a variable prognosis. The evidence on anosmia in COVID-19 patients is extremely limited, corresponding to a level 5 or D of the Centre for Evidence-Based Medicine. According to the available evidence, it seems reasonable to apply isolation, hygiene and social distancing measures in patients with recent olfactory disorders as the only symptom, although the usefulness of diagnostic tests for this type of patient should be studied.     

Comparison of diagnostic findings using different olfactory test methods

OBJECTIVE: To quantify discrepancies in the diagnosis of olfactory function that might exist when comparing results obtained from centers using different methods of olfactory testing. STUDY DESIGN: Prospective study of 50 healthy adult volunteers and 25 adult patients with olfactory complaints. METHODS: Two test methods, the Connecticut Chemosensory Clinical Research Center (CCCRC) test widely used in the United States, and the Jet Stream Olfactometer (JSO) test used in Japan, were used to measure and categorize the diagnostic level of olfactory function (normosmia, mild hyposmia, moderate hyposmia, severe hyposmia, anosmia). Olfactory function was measured separately for each nostril. RESULTS: There was a significant correlation (rs = 0.788, P < .01, n = 150 nostrils) between diagnostic categories assigned by the CCCRC and JSO test methods. Diagnostic categories were identical for 66.7% of the nostrils tested, and in only 7.3% of the cases did the results differ by more than one category. For the anosmic and normosmic categories, test results were in agreement 91.7% of the time, whereas for the hyposmic categories (mild, moderate, and severe) results were in agreement only 22.2% of the time. CONCLUSIONS: Our results demonstrate that when comparing clinical or research data obtained from centers using different olfactory test methods, subjects with diagnoses of anosmia or normosmia may be more reliably compared than those with different levels of hyposmia.     

Retronasal olfactory function in nasal polyposis

OBJECTIVE: To investigate the question of whether there is a difference in retronasal olfactory function between patients suffering from chronic rhinosinusitis with nasal polyposis (NP) and healthy controls. This question was based on the clinical observation that many of these patients present with smell loss without complaining about loss of the appreciation of foods. STUDY DESIGN: Open prospective study comparing symptomatic patients with healthy controls. METHODS: A total of 56 healthy volunteers and 42 NP patients were tested for orthonasal and retronasal odor identification. All subjects received detailed nasal endoscopy; NP was staged according to the Malm classification. Patients rated their olfactory function on visual analogue scales. Orthonasal testing was performed using the "Sniffin' Sticks" test kit. Retronasal testing was evaluated with odorized powders applied to the oral cavity. In both tests, subjects were asked to identify 10 items using a forced choice paradigm. RESULTS: Overall, odor identification was better in controls compared with NP patients (P <.001). Although controls exhibited no difference between orthonasal and retronasal smelling (P =.26), in NP patients, olfactory function was significantly better when odors were applied through the retronasal route (P <.001). Ratings of general olfactory abilities correlated with retronasal and orthonasal olfactory function in NP patients (P <.001) but not in healthy controls (P =.34). CONCLUSION: Better retronasal than orthonasal olfactory function seems to be associated with the presence of mechanical obstruction in the anterior portion of the olfactory cleft. In turn, these data indicate that olfactory loss in NP seems to be caused by regional mechanical or inflammatory factors.     

嗅裂疾病三例

目的报道一种新的嗅觉障碍疾病——嗅裂疾病，总结其临床特征、影像学特点以及治疗尝试。方法本组3例，均以完全失嗅为主诉。详细采集病史，行耳鼻咽喉科常规体检、鼻内镜检查。主观嗅功能测试使用T＆T标准嗅觉计行嗅觉察觉阈和识别阈测试。以醋酸异戊酯为刺激剂行嗅觉事件相关电位测试，刺激量为2ml。行鼻窦冠状位和轴位CT扫描。治疗方案：①抗生素治疗半个月；②糖皮质激素治疗半个月。结果鼻内镜检查患者双侧嗅裂处黏膜肿胀，嗅裂消失。T＆T主观嗅觉测试均为完全失嗅，最大嗅刺激未引出嗅觉事件相关电位。鼻窦CT提示局限于双侧嗅裂的软组织影。抗生素治疗嗅觉无改善。局部和全身糖皮质激素治疗，1例嗅觉改善，但停药后嗅觉又消失，再次使用糖皮质激素治疗无效。另2例嗅觉无改善。结论嗅裂疾病是一种以嗅觉障碍为主诉，病变局限于嗅裂的疾病，鼻窦CT有助于确诊，抗生素和糖皮质激素治疗效果不理想。     

Hazardous events associated with impaired olfactory function

OBJECTIVE: To evaluate the risk of olfactory-related hazardous events in patients with impaired olfactory function. DESIGN: Retrospective cohort study. SETTING: A university-based clinic for smell and taste disorders. PATIENTS: A total of 445 patients who underwent olfactory testing between 1983 and 2001. INTERVENTIONS: Patient interview, olfactory testing. MAIN OUTCOME MEASURES: (1) Frequency of olfactory-related hazardous events including cooking incidents (ie, burning pots or pans), undetected fires, undetected gas leaks, and ingestion of spoiled foods or toxic substances; (2) level of olfactory function (anosmia; severe, moderate, or mild hyposmia; or normosmia) as determined by olfactory testing. RESULTS: Olfactory testing revealed that 76% of patients had some degree of impairment; 30% had complete anosmia. Thirty-seven percent of patients with olfactory impairment but only 19% of patients without impairment experienced at least 1 olfactory-related hazardous event. Of the hazardous events reported by impaired patients, cooking-related incidents were most common, representing 45%, with ingestion of spoiled food (25%), inability to detect a gas leak (23%), and inability to smell a fire (7%) reported less frequently. There was a significant correlation between frequency of hazardous events and degree of olfactory impairment (Cochran-Armitage trend test, P<.001): at least 1 hazardous event was reported by 45.2% of patients with anosmia, 34.1% with severe hyposmia, 32.8% with moderate hyposmia, 24.2% with mild hyposmia, and 19.0% of patients with with normal olfaction by testing. CONCLUSION: Patients with impaired olfactory function are more likely to experience olfactory-related hazardous events than those with normal olfactory function.     

Multicenter investigation of 1,036 subjects using a standardized method for the assessment of olfactory function combining tests of odor identification, odor discrimination, and olfactory thresholds

“Sniffin’ Sticks” is a test of nasal chemosensory performance that is based on penlike odor-dispensing devices. It is comprised of three tests of olfactory function: tests for odor threshold, discrimination and identification. Previous work has already established its test-retest reliability and validity in comparison to established measures of olfactory sensitivity. The results of this test are presented as a composite TDI score – i.e., the sum of results obtained for threshold, discrimination and identification measures. The present multicenter investigation aimed at providing normative values in relation to different age groups. To this end, 966 patients were investigated in 11 centers. An additional study tried to establish values for the identification of anosmic patients, with 70 anosmics investigated in five specialized centers where the presence of anosmia was confirmed by means of olfactory evoked potentials. For healthy subjects, the TDI score at the 10th percentile was 24.5 in subjects younger than 15 years, 30.3 for ages from 16 to 35 years, 28.8 for ages from 36 to 55 years and 27.5 for subjects older than 55 years. While these data can be used to estimate individual olfactory abilities in relation to a subject’s age, hyposmia was defined as the 10th percentile score of 16- to 35-year-old subjects. Our latter study revealed that none of 70 anosmics reached a TDI score higher than 15. This score of 15 is regarded as the cut-off value for functional anosmia. These results provide the basis for the routine clinical evaluation of patients with olfactory disorders using “Sniffin’ Sticks.” Received: 29 May 1999 / Accepted: 9 September 1999     

Post-traumatic olfactory dysfunction

OBJECTIVES: This study demonstrates histopathologic and immunocytochemical changes in the olfactory bulb of a patient with post-traumatic olfactory dysfunction. These results are analyzed in light of current understanding of the pathophysiology of anosmia and dysosmia following head trauma. Emphasis is placed on potential mechanisms of human regeneration and recovery. STUDY DESIGN: The current study documents the history of a patient with the initial complaint of complete anosmia following minor head trauma. Two months after the injury the patient developed persistent, severe dysosmia with debilitating weight loss. Neurosurgical treatment, including removal of the olfactory bulbs and tracts, resulted in permanent resolution of dysosmia. METHODS: Histopathologic and immunocytochemical analysis of the olfactory bulbs was undertaken and compared with age-matched control tissue. RESULTS: Pathological analysis of the olfactory bulb revealed a marked reduction in the number of nerve processes with few intact olfactory glomeruli compared with an age-matched control. Specific immunohistochemical staining for the olfactory neuron-specific protein OMP, however, demonstrated the presence of intact axonal projections between the olfactory mucosa and the bulb. CONCLUSIONS: These results support the hypothesis that post-traumatic anosmia involves, at least in part, damage to peripheral olfactory nerve fibers with histological changes in the olfactory bulb. Potential mechanisms for the development of post-traumatic dysosmia are also discussed.     

Kallmann's syndrome and chemosensory evoked potentials

Summary Kallmann's syndrome is generally assessed by history and subjective tests of olfactory function. In this study three patients suffering from Kallmann's syndrome were investigated with more objective techniques, including the recording of chemosensory evoked potentials (CSEPs). After testing olfactory function by means of a simple odor identification test, anosmia was confirmed in only one patient, since the other two patients were able to distinguish between several odorants. However, investigations in which CSEPs were employed indicated that all three patients had complete loss of their olfaction as well as hypersensitivity of the trigeminal nerve. These findings prove the usefulness of CSEPs in clinical investigations of the sense of smell. Offprint requests to: T. Hummel     

Special characteristics of expert assessment of olfactory and taste disorders]

BACKGROUND: The number of medical expert opinions dealing with smell and taste disorders has continuously increased in recent years. However, an overview of the specific problems and results of those expert opinions has not been published until now. INDIVIDUALS AND METHODS: Olfaction was assessed by multiple subjective tests in 145 individuals with chemosensory dysfunction caused by trauma or occupational and environmental exposures. Additionally, a gustatory test, nasal endoscopy, anterior rhinomanometry, and radiography of the paranasal sinuses were performed. Malignering was diagnosed on a trial of multiple symptoms. Retronasal olfaction was tested using the Güttich gustatory olfaction test. RESULTS: Most of the medical expert opinions have been ordered by professional associations (42%) and insurance companies (28%). Compensation for olfactory dysfunction was claimed after trauma (64%), occupational exposure (23%) rhinosurgical procedures (8%), and laryngectomy (5%). Anosmia or hyposmia was claimed by 66% and 24% of all individuals, respectively. According to the results of the chemosensory tests, 41% of patients suffered from anosmia and 40% had hyposmia. Malignering was registered in 14%. CONCLUSIONS: The study shows that the "characteristic case" is a male in the late fourties, complaining of anosmia initially noticed after an occipital or frontobasal head trauma. The assessment of olfactory deficits related to toxic or chemical occupational exposure is difficult when a latency between the occupational exposure and the onset of chemosensory dysfunction is present. Moreover, interactions between the occupational exposure and nicotine or alcohol abuse must be taken into consideration. Claims for medical liability arose in 3% of the study group after septoplasty and sinus surgery.