Orthonasal Olfactory Function Research Articles

SNOT-22 in general population, a Spanish cohort study with an updated meta-analysis.

Olfactory loss (OL) has emerged as one of the most prevalent and debilitating symptoms of SARS-CoV-2 infection and long-COVID-19. The present prospective observational study aimed to evaluate the efficacy of olfactory training (OT) on orthonasal and retronasal olfactory function in a cohort of individuals with persistent post-COVID-19 OL. Participants with post-COVID-19 olfactory impairment underwent 4 months of OT, self-assessing their smell perception and undergoing comprehensive psychophysical evaluation of orthonasal and retronasal olfaction at baseline and after training. Orthonasal olfactory function was assessed using the extended Sniffin' Sticks test battery. Retronasal olfactory function was tested with powdered aromas. Among 114 participants with post-COVID-19 olfactory loss, adherence to OT was 60%. In adherents, the average increase in composite TDI score was 6.0 points compared to 2.6 points in non-adherents. Fifty-seven percent of adherent participants achieved a clinically significant improvement in TDI score (≥5.5 points), compared to 22% of non-adherents. In retronasal olfactory identification, 56% of adherents achieved a clinically significant improvement (≥4 points), compared to 16% of non-adherents. Adherence to a 4-month OT regimen can yield clinically meaningful improvements in both orthonasal and retronasal olfactory function among individuals with persistent post-COVID-19 olfactory dysfunction.

Assessment of olfactory fluctuations in a clinical context

PurposeThe aim of the study was to investigate whether olfactory fluctuations (OF) are pronounced in patients with sinonasal olfactory dysfunction (OD).MethodsThe retrospective investigation included patients aged 18 years or older, who consulted a tertiary referral center for olfactory loss. Patients with normal smell function were excluded. Patients answered a structured questionnaire about their olfactory symptoms, with specific questions related to the presence of OF and its average frequency, amplitude, duration, time since most recent OF, and associated symptoms of self-reported OF. Patients also underwent clinical evaluation including a structured medical history and physical examination including nasal endoscopy. In addition, we assessed orthonasal olfactory function using Sniffin’ Sticks, and gustatory function using “taste sprays”.ResultsParticipants included 131 men and 205 women (n = 336), aged 18 to 86 years (mean 50, SD 16). Patient-reported fluctuations occurred most frequently in sinonasal (38%), idiopathic (29%), and postviral (29%) OD. Amplitude of OF was highest in postviral OD (p = 0.009). Average frequency, duration, and the time since the most recent fluctuation were not significantly different between groups (all p’s > 0.42). Odor discrimination (p = 0.002) and identification (p = 0.017) scores were higher among those individuals with OF.ConclusionAmplitude of OF may help distinguish postviral from other causes of OD, especially in patients presenting with equivocal symptoms of sinonasal disease.

Validation study of a novel approach for assessment of retronasal olfactory function with combination of odor thresholds and identification.

PurposeThe present study aimed to establish a test battery for the clinical assessment of retronasal odor thresholds and retronasal odor identification.Study designProspective case–control series.MethodsSixty participants (36 women, 24 men, mean age 37.6 ± 19.4 years) were enrolled in this study; 36 were healthy controls and 24 were patients with olfactory dysfunction. Orthonasal olfactory function was assessed with the “Sniffin’ Sticks” test battery. Retronasal olfaction was assessed with oral odorant delivery using special containers for threshold function, and with oral tasteless powders for odor identification.ResultsRetronasal and orthonasal olfaction were significantly correlated for threshold scores, identification score, and the sum of threshold and identification score (TI score). Validity analyses showed that the retronasal TI score was able to discriminate between healthy controls and patients with olfactory dysfunction.ConclusionsNormosmic participants can be distinctly differentiated from patients with olfactory dysfunction using a valid test battery comprised of retronasal threshold and identification tests. Based on the current findings, we advocate a TI score of 16 as a cut-off between patients and controls. Therefore, TI scores of 17 and above would indicate retronasal normosmia.

Determination of Retronasal Olfactory Threshold Values.

The aim of this study was to generate normative data of retronasal olfactory threshold values for normosmic and hyposmic individuals and to test the validity of that data by determining the discriminative power for normosmic/hyposmic differentiation. Prospective, descriptive and methodological study. The orthonasal olfactory function of 20 normosmic and 20 hyposmic cases was evaluated using the Sniffin' Sticks Olfactory test. Sniffin' Sticks odor threshold, odor discrimination, and odor identification values and threshold discrimination identification (TDI) scores were recorded. A 13-item test battery previously prepared in our Rhinology Laboratory for retronasal olfactory threshold test that consisted of concentrated solutions prepared from 2:1 diluted 99% phenylethyl alcohol (PEA) and water was used. Each concentration was evaluated with water control, and if not answered correctly, the same process was continued by moving to a higher concentration series. Four consecutive correct answers were determined as the patient's retronasal olfactory threshold. A strong correlation was found between Sniffin' Sticks TDI scores and retronasal odor threshold values in the normosmic group (P < .001, r:0.67). A very strong correlation was found between Sniffin' Sticks TDI scores and retronasal olfactory threshold values in the hyposmic group (P < .001, r:0.81). Furthermore, receiver operating characteristic (ROC) analysis revealed that the sensitivity and the specificity of normosmic/hyposmic differentiation of retronasal olfactory threshold test was 95% and 100%, respectively. The diagnostic cutoff value was 8.5. This study shows that the retronasal olfactory test, a psychophysical odor test performed using an orally presented stimulus, can be used to differentiate normosmic and hyposmic cases. 3 Laryngoscope, 131:1608-1614, 2021.

Data Science-Based Analysis of Patient Subgroup Structures Suggest Effects of Rhinitis on All Chemosensory Perceptions in the Upper Airways

Viral rhinitis contributes significantly to olfactory dysfunction, but it is unclear how many patients have other chemosensory symptoms in addition to olfactory loss. This was addressed in the present reanalysis of data previously published in Pellegrino R, Walliczek-Dworschak U, Winter G, Hull D, Hummel T. 2017. Investigation of chemosensitivity during and after an acute cold. Int Forum Allergy Rhinol. 7(2):185-191, using unsupervised and supervised machine-learning methods. Fifty-eight patients with acute rhinitis and 59 healthy controls were assessed for orthonasal and retronasal olfactory function, taste, and intranasal trigeminal sensitivity. Unsupervised analysis showed that during rhinitis, clinical scores of olfactory function, expressed as threshold, discrimination, identification (TDI) values, were trimodally distributed. Two minor modes were separated from the main mode at TDI = 30.5, which corresponds to the established limit of hyposmia. This trimodal distribution was not observed after the rhinitis subsided. Olfactory function was not significantly impaired in 40% of all rhinitis patients, whereas it was transiently impaired in 59%. For this group, supervised machine-learning algorithms could be trained with information on retronasal olfactory function, gustatory function, and trigeminal sensitivity to assign patients to subgroups based on orthonasal olfactory function with a balanced classification accuracy of 64-65%. The ability to recognize patients with olfactory loss based on retronasal olfactory function as well as gustatory function and trigeminal sensitivity suggests in turn that these modalities are affected by rhinitis. However, the only modest accuracy at which this information allowed to reproduce the olfactory diagnosis indicated they are involved in the symptomatology of rhinitis to a lesser extent compared with the orthonasal olfactory function.

Radiological Markers of the Olfactory Cleft: Relations to Unilateral Orthonasal and Retronasal Olfactory Function

The opacification of the olfactory cleft (OC) has been associated with birhinal orthonasal olfaction in patients with chronic rhinosinusitis (CRS). The aim of this study was to determine the associations between monorhinal and birhinal orthonasal, and retronasal olfaction with radiological markers of the OC in a cohort of patients with CRS. Results were analyzed in a CRS-cohort including 13 patients with nasal polyposis (CRSwNP) and 12 patients with non-eosinophilic CRS (non-eCRS). Monorhinal and birhinal orthonasal olfactory function, and OC-air volume were higher in non-eCRS compared CRSwNP. OC-opacification was also higher in CRSwNP compared to non-eCRS. In the entire CRS-cohort, those with higher OC-opacification showed significantly lower orthonasal and retronasal olfactory test results compared to those with lower OC-opacification across all three coronal planes. Similarly, higher unilateral OC-opacification was also associated with lower ipsilateral orthonasal olfactory function. Correlation analysis further revealed a positive correlation between monorhinal and birhinal orthonasal olfaction with ipsilateral and overall OC-air volume. Likewise, birhinal and monorhinal orthonasal, and retronasal olfactory test results correlated negatively with the overall and ipsilateral Lund-Mackay scores. Monorhinal and birhinal orthonasal, and retronasal olfactory function were lower in CRS patients with higher ipsilateral and overall OC-opacification compared to those with lower OC-opacification.

Self-perceived Taste and Flavor Perception: Associations With Quality of Life in Patients With Olfactory Loss.

To evaluate associations between self-perceived chemosensory functions of smell, taste, and flavor perception with olfactory-specific quality of life (QoL) in patients with olfactory dysfunction (OD) and whether these associations would be influenced by other factors, such as duration or etiology of smell loss. Retrospective cohort study. Tertiary care, academic center. Olfactory-specific QoL was measured with the Questionnaire of Olfactory Disorders (QOD). The QOD measures the impact of OD on QoL (QOD-negative statements) and the ability of patients to cope with smell loss (QOD-positive statements). Orthonasal olfactory function, patients' demographics, self-perceived chemosensory perception, and duration and etiology of OD were retrospectively collected in a cohort of patients with quantitative OD. Correlations and multivariable linear regression models were computed to determine possible associations with the outcome measure of QOD-negative and QOD-positive statement scores. A total of 133 patients with OD were included. Analysis revealed a positive correlation between self-perceived taste and flavor perception with QOD-negative statement scores, while self-perceived smell showed no significant correlation. Similarly, longer duration of smell loss and higher age were also correlated with higher QOD-positive statement scores. Multivariable regression models confirmed that self-perceived taste was independently associated with the QOD-negative statement score, while age and duration of OD were independently associated with the QOD-positive statement score. These findings suggest that the impact of diminished flavor perception during eating and drinking has a stronger impact on the QoL of patients with OD as compared with decreased orthonasal olfaction.

Characteristics of Olfactory Disorder With and Without Reported Flavor Loss.

Quality of life related to olfactory disorder (OD) depends on the perceived impairment. It is not known why some patients with OD report smell and flavor loss while others report smell loss only. In order to understand this, we compared the two clinical presentation forms in terms of demographics, clinical features, and orthonasal olfaction test results. Observational, analytic, cross-sectional study. A total of 401 patients with measured orthonasal OD presenting at a tertiary referral center were divided in 2 groups according to their subjective reports (smell loss only = 129 patients vs. smell and flavor loss = 272 patients). Groups were compared in terms of demographic (age, sex), clinical features (duration of disease, type of onset, etiology, degree of impairment due to the disorder) and test results (taste and orthonasal olfaction). Groups did not differ in terms of age, sex distribution, orthonasal olfactory, or taste function. Patients reporting smell and flavor loss were characterized by a mainly sudden onset of the disorder and a predominance of postinfectious olfactory loss. They also have a shorter disease duration and a higher disease impairment. For patients reporting smell loss only, disease duration is longer, they feel less impaired, the onset of the disorder is to a higher degree protracted and the main cause is idiopathic. Patients with orthonasal OD reporting smell and flavor loss feel more impaired and present significant different clinical features compared to patients reporting smell loss only. Future studies measuring retronasal olfaction are necessary to fully understand flavor perception in OD. 4 Laryngoscope, 130:2869-2873, 2020.

A New Method for Assessment of Retronasal Olfactory Function

The aim of the study was to develop a test for the assessment of retronasal olfaction in healthy participants and patients with olfactory disorders using "tasteless" powders. Prospective case-control series. A total of 150 participants (110 women, 40 men, mean age = 40 ± 16 years) were recruited for this study; 100 were healthy controls and 50 were patients with olfactory loss due to infections of the upper respiratory tract (n = 25), idiopathic causes (n = 12), sinonasal disease (n = 7), and head trauma (n = 6). Orthonasal olfactory function was evaluated using the Sniffin' Sticks test battery, and retronasal olfaction was evaluated using powders lacking distinctive tastes administered to the oral cavity. To establish test-retest reliability, healthy participants had their orthonasal and retronasal function tested twice. The validity analyses revealed that the selected 16 stimuli differentiated between normosmic participants and patients with olfactory loss, and that retronasal and orthonasal olfaction were highly correlated. The results of the present study indicate that patients with olfactory loss and controls can be clearly separated using a reliable test of retronasal olfaction based on 16 retronasal stimuli. 2b Laryngoscope, 131:E324-E330, 2021.

Body-Mass-Index Associated Differences in Ortho- and Retronasal Olfactory Function and the Individual Significance of Olfaction in Health and Disease.

Odor (including flavor) perception plays a major role in dietary behavior. Orthonasal olfactory function (OOF) has been shown to decrease in obese subjects. Changes in retronasal olfactory function (ROF) after weight loss and in the individual significance of olfaction (ISO) in obesity are yet to be investigated. Firstly, 15 obese subjects were recruited in a pilot study and supported to conventionally lose weight. OOF (Sniffin’ Sticks) was measured at the beginning and after 5.6 ± 1.3 months. Eleven subjects re-visited but barely lost weight and no major changes in OOF were observed. Secondly, the body-mass-index (BMI), OOF, and ROF (Candy Smell Test, CST) were recorded in subjectively olfactory-healthy subjects (SOHSs) and additionally the ISO questionnaire was collected in patients with olfactory dysfunction (OD). BMI correlated significantly negatively with odor discrimination (p = 0.00004) in 74 SOHSs and negatively with CST (p < 0.0001) in 66 SOHSs. In 48 SOHSs, there was a gender difference in ISO scores (p = 0.034), but no significant correlation with BMI was found (p > 0.05). ISO scores were significantly higher in 52 OD patients in comparison to SOHSs (p = 0.0382). Not only OOF but also ROF may decline with higher BMI. ISO does not seem to alter with BMI, but olfaction becomes more important once it is consciously impaired.

Quality of Life in Patients With Olfactory Loss Is Better Predicted by Flavor Identification Than by Orthonasal Olfactory Function.

To date, most studies on the relationship between chemosensory performance and quality of life have focused on orthonasal measures of olfactory function. In the current investigation, we examined the predictive value of orthonasal and flavor identification indices of olfactory function on a wide spectrum of health and sociopsychological factors, including quality of life, life satisfaction, overall health, and depressive symptoms. Participants were 178 ENT patients (Mage = 58 ± 1), representing various causes of olfactory loss: idiopathic smell loss (n = 51; Mage = 63 ± 2), sinunasal disease (n = 27; Mage = 56 ± 3), head trauma (n = 33; Mage = 51 ± 2), and infections of the upper respiratory tract (n = 67; Mage = 59 ± 2). They completed self-report questionnaires and underwent olfactory testing using Sniffin' Sticks (orthonasal olfactory testing) and "Taste Powder" (intraorally applied flavors for retronasal olfactory testing, additionally inducing taste sensation). Data were analyzed with hierarchical regression models wherein the first step included subjects' sex, age, and orthonasal olfaction score. In the second step, we included the "Taste Powder" score. Tested models revealed that the first step was not significantly predicting variables of interest; however, there was an improvement of the model's predictive value when the "Taste Powder" score was added. Results of this study suggest that flavor identification significantly improves predictions of health and sociopsychological functioning of ENT patients with various etiologies.

Retro- and orthonasal olfactory function in relation to olfactory bulb volume in patients with hypogonadotrophic hypogonadism.

IntroductionIdiopathic hypogonadotrophic hypogonadism with an olfactory deficit is defined as Kallmann syndrome and is distinct from normosmic idiopathic hypogonadotrophic hypogonadism.ObjectiveBecause olfactory perception not only consists of orthonasally gained impressions but also involves retronasal olfactory function, in this study we decided to comprehensively evaluate both retronasal and orthonasal olfaction in patients with idiopathic hypogonadotrophic hypogonadism.MethodsThis case-control study included 31 controls and 45 idiopathic hypogonadotrophic hypogonadism patients. All participants whose olfactory and taste functions were evaluated with orthonasal olfaction (discrimination, identification and threshold), retronasal olfaction, taste function and olfactory bulb volume measurement. The patients were separated into three groups according to orthonasal olfaction: anosmic idiopathic hypogonadotrophic hypogonadism, hyposmic idiopathic hypogonadotrophic hypogonadism and normosmic idiopathic hypogonadotrophic hypogonadism.ResultsDiscrimination, identification and threshold scores of patients with Kallmann syndrome were significantly lower than controls. Threshold scores of patients with normosmic idiopathic hypogonadotrophic hypogonadism. were significantly lower than those of controls, but discrimination and identification scores were not significantly different. Retronasal olfaction was reduced only in the anosmic idiopathic hypogonadotrophic hypogonadism group compared to controls. Identification of bitter, sweet, sour, and salty tastes was not significantly different when compared between the anosmic, hyposmic, and normosmic idiopathic hypogonadotrophic hypogonadism groups and controls. Olfactory bulb volume was lower bilaterally in all patient groups when compared with controls. The olfactory bulb volume of both sides was found to be significantly correlated with threshold, discrimination and identification scores in idiopathic hypogonadotrophic hypogonadism patients.Conclusion1) There were no significant differences in gustatory function between controls and idiopathic hypogonadotrophic hypogonadism patients; 2) retronasal olfaction was reduced only in anosmic patients but not in orthonasally hyposmic participants, possibly indicating presence of effective compensatory mechanisms; 3) olfactory bulb volumes were highly correlated with olfaction scores in the hypogonadotrophic hypogonadism group. The current results indicate a continuum from anosmia to normosmia in idiopathic hypogonadotrophic hypogonadism patients.

Continuous positive air pressure improves orthonasal olfactory function of patients with obstructive sleep apnea

ObjectiveRecent studies have suggested that patients with obstructive sleep apnea (OSA) might be affected by olfactory impairment. However, more evidence is needed on the effect that OSA has on the chemical senses (olfaction and gustatory) of these patients, and whether continuous positive airway pressure (CPAP) treatment might help to reverse possible impairment. MethodsA prospective study was conducted with 44 OSA patients (17 female and 27 male, mean age 54 ± 9.9 years) who were diagnosed via polysomnography and eligible for CPAP treatment. Orthonasal olfactory and gustatory function was measured with the extended Sniffin' Sticks test battery and “taste strips,” respectively, before and after CPAP treatment. ResultsBaseline olfaction was decreased in OSA patients and after CPAP therapy olfactory scores (odor threshold-discrimination-identification score [TDI]: baseline 29.4 ± 4.11 after CPAP 32.3 ± 4.82; p = 0.001; odor threshold [THR]: baseline 5.28 ± 1.69 after CPAP 6.78 ± 2.61; p = 0.000; odor identification [ID]: baseline 12.9 ± 1.95 after CPAP 13.6 ± 1.33; p = 0.013) improved significantly. In contrast, neither baseline taste function in OSA patients nor gustatory function after treatment seemed to be affected. ConclusionOrthonasal olfactory function in patients with OSA improves under CPAP therapy; however, gustatory function is not impaired in OSA patients.

Olfactory and Gustatory Function After Bariatric Surgery.

Neither hormone levels nor malabsorption alone fully explains the distinct weight loss after bariatric surgery in morbidly obese patients. Postoperatively, patients regularly report a change in the sense of taste and the development of food aversions. Hedonic and sensory components like olfactory and gustatory stimuli significantly affect appetite and flavour. We prospectively analysed the orthonasal olfactory and gustatory function with psychophysical testing in 44 patients undergoing laparoscopic Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG) or adjustable gastric banding (AGB) and in 23 healthy controls. About 22.7 % of morbidly obese patients were hyposmic, showing significantly lower threshold-discrimination-identification (TDI) scores (p = 0.009) with decreased discrimination and identification ability. In addition, 22.7 % of patients were tested to be limited in gustatory function, with significantly lower taste strip test (TST) scores (p = 0.003). Six months after surgery, olfactory and gustatory function was not different when compared to healthy controls. Due to obesity, patients frequently show impaired olfactory and gustatory function. Six months after laparoscopic bariatric surgery, both chemosensory functions improve. The TDI test is an appropriate tool to measure olfactory function in obese patients.

Volume of olfactory bulb and depth of olfactory sulcus in 378 consecutive patients with olfactory loss.

The aim of this study was to investigate the olfactory bulb (OB) and sulcus (OS) in a large group of patients who have been well-characterized in terms of olfactory function, with a specific focus on the comparison between patients with olfactory loss due to chronic rhinosinusitis, head trauma, or acute infections. A retrospective study of 378 patients with olfactory loss was performed. Orthonasal olfactory function was assessed with the"Sniffin' Sticks" test kit, including tests for odor threshold, odor discrimination, and odor identification. Magnetic resonance imaging analyses were focused on OB volume and OS depth. Major results of the present study included the (1) demonstration of a correlation between olfactory function and OB volume across the various pathologies in a very large group of subjects; (2) the three functional tests exhibited a similar degree of correlation with OB volume. (3) The right, but not the left OS correlated with olfactory function; in addition, (4) OS was negatively correlated with age. In contrast to OS, (5) no side differences were found for the OB. Finally, (6) the three different causes of olfactory loss exhibited different patterns of results for the three olfactory tests. The present data suggest that the morphological assessment of the OB volume and OS depth produces useful clinical indicators of olfactory dysfunction.

An investigation of retronasal testing of olfactory function in a Turkish population

BackgroundThe aim of this study was: (1) to perform a preliminary study for the validation of “retronasal olfactory testing” in the Turkish population to find the best way to evaluate smell and taste disorders in Turkey; (2) to determine if cultural differences make application of the test more difficult; and (3) to determine the flavors that participants had not yet tasted by using the survey method.Material/MethodsThe study included 330 volunteers. Orthonasal olfactory function was assessed psycho-physically using the “Sniffin’ Sticks” olfactory test. Retronasal olfaction was assessed using a collection of 20 available food powders applied to the oral cavity. Also, all participants filled in a questionnaire of 50 items about the flavors they had not tasted before.ResultsThe mean age of the participants was 26±7.3 years. Participants were divided into 3 groups according to the “Sniffin’ Sticks” test results: anosmia, hyposmia, and normosmia groups. Differences in retronasal olfaction scores were significant among the 3 groups.ConclusionsThe retronasal olfactory test appeared to perform well, but modifications of odorized powders or granules and distracters used in the retronasal olfactory test, taking into account Turkish cultural differences, is likely to improve its performance.

Psychophysiological and electrophysiological testing of olfactory and gustatory function in patients with multiple sclerosis

The olfactory (OF) and gustatory function in multiple sclerosis (MS) patients and possible influencing variables of the disease, such as depression or fatigue, were determined. In an open prospective controlled clinical study 30 patients with MS and 30 healthy controls matched for age, sex and smoking-habits were investigated. With Mini Mental State Examination cognitive dysfunction was excluded, with Expanded Disability Status Scale the patient's ability to accomplish the tests was ensured. The severity of depression was measured with the self-reported Beck Depression Inventory. The orthonasal olfactory function was derived with olfactory event related potentials (OERP) and TDI-score (Threshold, Discrimination and Identification, Sniffin' Sticks). Retronasal olfactory function was tested with Taste-Powder-score, gustatory function with Taste-strip-score. There was a significant loss of olfactory function measured with TDI-score [12/30 (40%), p = 0.002] and gustatory function [5/23 (21.7%), p < 0.001] in MS-patients, 23.8% (5/21) of MS-patients showed hyposmia with OERPs, significantly correlating with the TDI-score (p = 0.03). The Expanded Disability Status scale score inversely correlated with the TDI-score (p = 0.002). This study confirms the incidence of olfactory disorder in MS-patients and reveals a frequent gustatory deficit. The Identification subtest can be proposed as a marker of the OF in MS-patients: it includes complex cognitive tasks and may be influenced by depression and fatigue, which are common symptoms of MS. It inversely correlates with the disability status.

Reduced olfactory bulb volume in total laryngectomy patients: a magnetic resonance imaging study

The olfactory bulb (OB) is a remarkably plastic structure with highly active afferent neurons, which is partly reflected by its volume. Although deterioration of olfaction after total laryngectomy is reported by many patients, this problem has not received widespread attention. There has been no study that had addresses this loss olfactory ability as a function of OB volume. The aim of this study was to determine OB volume changes after laryngectomy. Twenty one patients post-total laryngectomy and 17 subjects with normal olfactory function underwent magnetic resonance imaging (MRI) for volumetric measurement of the OB. The history of all participants was taken in detail to exclude other possible causes of smell dysfunction. Volumetric measurement of the OB was performed by manual segmentation of the OB into coronal slices. Olfactory function was assessed with the orthonasal olfaction test. There was no statistically significant difference in volume between the right and left sides of the OB in the study and control groups. However, the study group had smaller OB volumes than the control group. In our assessment of orthonasal olfaction, patients who were post-total laryngectomy had worse orthonasal olfactory function than the control group. There were significant correlations between OB volumes and orthonasal test scores. Our MRI study showed that post-total laryngectomy patients had higher rates of olfactory bulb atrophy than the control subjects. Laryngectomy is associated with measurable decreases in olfactory function and this study hopes to further clarify this association by demonstrating that patients with total laryngectomy have reduced OB volumes when compared to the normal population.

Retronasal olfactory function in Parkinson's disease

Orthonasal olfaction is severely altered in PD patients. Retronasal olfactory function has been shown to be preserved under certain conditions even in the absence of orthonasal function. This study was undertaken to investigate retronasal versus orthonasal olfactory function in Parkinson's disease (PD). Prospective study. A total of 45 PD patients (mean age, 61 years; range 26-82 years) underwent orthonasal olfactory testing with a standardized olfactory test (Sniffin' Sticks) and retronasal olfactory testing with a 10-item identification kit based on aromatized powders. Regarding orthonasal tests, all PD patients scored within the range of hyposmia and functional anosmia. The mean correct orthonasal identification score for PD patients was 56% +/- 2.6%, and the mean retronasal identification rate was 60% +/- 3%. There was no significant difference between ortho- and retronasal odor identification (P = .15). The present study shows that retronasal and orthonasal olfactory function are severely impaired in PD patients, and this impairment is of similar magnitude for both functions. The contribution of this finding to the food-intake behavior of PD patients is discussed.

Can we Smell without an Olfactory Bulb?

Lack of an olfactory bulb (OB) is typically associated with anosmia. We present a patient with subnormal olfactory function in whom the OB could not be detected with magnetic resonance imaging (MRI). 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. This indicates that olfactory function may be present in some subjects even when an OB can not be detected with MRI.