Retronasal Olfactory Testing Research Articles

Investigating a Clinical Case of Deluded Gustatory Perception

Introduction: Hypergeusia is a taste disturbance with an increased perception of taste. Delusional hypergeusia has not heretofore been reported. Case Report: A 62-year-old right-handed woman described a plethora of complaints after exposure to a solvent aroma, including headaches, diffuse weakness, fatigue, hallucinated smells and tastes, Burning Mouth Syndrome, and panic attacks. The apogee of her symptoms was that the salty taste was 800% normal. Sugar was also too sweet, 600% of normal. Results: Motor Examination: Drift Test: right pronator drift with right abductor digit minima sign. Gait Examination: heel walking with bilateral decreased arm swing. Reflexes: bilateral quadriceps femoris 3+, positive left (L) Hoffman’s reflex. Retro nasal Olfactory Testing: Retro nasal Smell Index: 1 (Anosmia). Waterless Empirical Taste Test: sweet: 4, sour: 3, salty: 7, bitter: 5, brothy: 0, total: 30 (ageusia to Unami, otherwise normogeusia). Neuropsychiatric Testing: Go-No-Go Test: 2/6 (abnormal). Discussion: Perhaps, hypergeusia may not have been true, but a misperception of retro nasal smell associated hypersomnia with physiologic synesthesia manifested as taste. The perceived delusional hypersomnia may intensify the sensory misperception due to underlying dysgeusia. This may represent a variant of the two-factor hypothesis of delusions whereby a distorted sensory perception is then misrepresented in a delusion. Dysfunction of the right hemisphere, which usually acts to censor the left, allows the delusion to manifest. While two different anatomical abnormalities (one left and one right hemisphere) have been postulated to be the foundation of such delusions, it is distinctly possible that a single lesion of the inferior parietal lobule may be sufficient for both sensory distortions to be produced as well as loss of inhibition of delusional interpretation of distorted sensation of the frontal lobe by the right parietal lobe, yclept the sensorial hypothesis. A search for delusional origin is warranted for those who present with hypergeusia. Conclusion: In those who present with hypergeusia, a search for delusional origin is warranted, and for those who present with delusions, a query to perceive hypergeusia may be revealing

Too Sweet to Eat: Delusional Hypergeusia

AbstractIntroductionDelusional hypergeusia has not heretofore been reported.Methods: Case reportA 62-year-old right-handed woman described a plethora of complaints after exposure to a solvent aroma, including headaches, diffuse weakness, fatigue, hallucinated smells and tastes, burning mouth syndrome, and panic attacks. The apogee of her symptoms was that salty taste was 800% of normal, making food taste disgustingly salty. She was unable to tolerate potato chips, pizza, spaghetti sauce, Coca Cola, root beer, Sprite, 7 Up, and even bottled water. Sugar was also too sweet, 600% of normal. Foods which were unbearably sweet included cookies, sugar, and breakfast cereals. Sour and bitter were normal.ResultsAbnormalities in Neurological Examination: Mental Status Examination: hyperverbal, loud, overly inclusive, irritable with pressured speech; disheveled, racing thoughts, and tangential. Motor Examination: Drift Test: right pronator drift with right abductor digiti mini sign. Gait Examination: heel walking with bilateral decreased arm swing. Reflexes: bilateral quadriceps femoris 3+, positive left (L) Hoffman’s reflex. Chemosensory Testing: Olfaction: Brief Smell Identification Test: 12 (normosmia). Retronasal Olfactory Testing: Retronasal Smell Index: 1 (Anosmia). Gustatory Testing: Propylthiouracil Disc Taste Test: 10 (normogeusia). Waterless Empirical Taste Test: sweet: 4, sour: 3, salty: 7, bitter: 5, brothy: 0, total: 30 (ageusia to umami, otherwise normogeusia). Neuropsychiatric Testing: Go-No-Go Test: 2/6 (abnormal).DiscussionPerhaps hypergeusia may not have been true hypergeusia but a misperception of retronasal smell associated hyperosmia with physiologic synesthesia manifested as taste. Peradventure, the perceived hypergeusia, is just one component of a generalized delusional paradigm, where many sensory perceptions are intensified. The perceived delusional hyperosmia may be intensification of the sensory misperception due to an underlying dysgeusia. This may represent a variant of the two-factor hypothesis of delusions whereby a distorted sensory perception is then misrepresented in a delusion. Dysfunction of the right hemisphere, which normally acts to censor the left, allows the delusion to manifest. While two different anatomical abnormalities (one left and one right hemisphere) have been postulated to be the foundation of such delusions, it is distinctly possible that a single lesion of the inferior parietal lobule may be sufficient for both sensory distortions to be produced as well as loss of inhibition of delusional interpretation of distorted sensation of the frontal lobe by the right parietal lobe, yclept the sensorialist hypothesis. In those who present with hypergeusia, search for delusional origin is warranted and in those who present with delusions, query as to perceived hypergeusia may be revealing.FundingNo Funding

Beyond aroma: A scoping review on the impact of chronic rhinosinusitis on retronasal olfaction.

BackgroundRetronasal olfaction (RNO) refers to the perception of odorants inhaled through the mouth and carried through the nasopharynx to olfactory receptors within the olfactory cleft, enabling the perception of flavor. Although orthonasal olfactory dysfunction in chronic rhinosinusitis (CRS) has been widely described, the impact of CRS on RNO is less clear. In this study, we systematically review available literature to provide an update on RNO in the setting of CRS.MethodsWe systematically searched PubMed, Ovid Embase, Web of Science, and the Cochrane Library for studies examining RNO in patients with documented CRS. The primary outcome of interest was objective psychophysical measurement of olfaction, including characterization of RNO.ResultsWe identified 404 unique references that underwent title and abstract review by two independent reviewers, with 52 articles undergoing full-text review, where 10 relevant studies underwent data extraction. Although outcome measures varied, all included studies demonstrated diminished RNO in patients with CRS. Of six studies evaluating the relationship between retronasal and orthonasal olfactory test scores in CRS patients two out of six (33%) demonstrated a correlation between both forms of olfaction and CRS, and two out of six studies (33%) found significantly lower orthonasal olfactory test scores compared to retronasal olfactory test scores. Two of three found significant improvement in RNO with treatment of underlying CRS. Of three studies examining patient reported outcome measures (PROMs) in CRS, two found significant associations between retronasal olfactory test scores and PROMs.ConclusionsBased on the current literature, CRS patients appear to have diminished RNO, which may be associated with orthonasal olfactory dysfunction and decreased quality of life in this population. Higher level of evidence studies are required to further elucidate these relationships and the impact of medical and surgical CRS management on RNO.

Danish Validation of a Retronasal Olfactory Powder Test and Development of a Novel Quick Retronasal Olfactory Test.

Introduction Quality of life is closely linked to retronasal olfactory function. Familiarity with odors vary, so tests need validation. Testing can be time-consuming, so a quick test and a thorough test are needed for clinical and research settings. Objectives The objectives of this study were to validate the original retronasal powder olfactory test in a Danish population and to develop a novel quick retronasal test for easy application. Methods Ninety-seven participants were included in the study, 59 healthy controls and 38 patients with olfactory impairment. The retronasal test was modified by substituting unfamiliar odors and descriptors and validated with a criterion of correct identification rate of 50% in the original test and 90% in the quick test. Items with over 90% correct identification rate in the modified original test were included in the quick test, resulting in a 10-item test. Results The modified retronasal olfactory test achieved good test characteristics, with a 10th percentile cut-off value of 13: sensitivity was 88.9%, specificity 83.0%, positive predictive value 78%, negative predictive value 91.7%, and the receiver operating characteristics area under the curve (ROC-AUC) was 0.86. The quick test achieved acceptable test characteristics, with a 10th percentile cut-off value of 8.2: sensitivity was 72.2%, specificity 90.6%, positive predictive value 83.9%, negative predictive value was 82.8%, and ROC-AUC 0.81. Conclusion Validation of both tests demonstrated satisfactory accuracy. We recommend the quick test for screening purposes, and the modified original version for a thorough evaluation. The tests are easily implemented as they are easy to understand and very affordable.

Retronasal olfactory testing in early diagnosed and suspected COVID-19 patients: a 7-week follow-up study

ObjectivesOlfactory dysfunction (OD) constitutes a major symptom in Coronavirus Disease 2019 (COVID-19). Yet, most data on smell loss rely on the evaluation of orthonasal olfactory performance. Therefore, we aimed to assess retronasal olfactory function (ROF) over a period of several weeks in proven and suspected COVID-19 patients.MethodsOne hundred and one subjects with suspected or laboratory-proven COVID-19 participated in this study. In patients with OD no longer than 4 weeks after initial symptom onset, ROF was measured with the 7-item Candy Smell Test ten times over 7 weeks.ResultsOlfactory function was decreased in the investigated patients and remained decreased over the course of 7 weeks. One-way repeated-measures ANOVA revealed no significant difference of ROF between different measurement time points. However, self-assessment of smell and flavour improved significantly (p = 0.013 and p = 0.043), but did not show complete recovery.ConclusionThe current investigation revealed significant improvements in subjective smell and flavour perception over the course of 7 weeks in proven and suspected COVID-19 patients suffering from acute OD. However, objectively measured ROF based on a screening test revealed no improvements within the same time period.

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.

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.

Orthonasal, but not Retronasal Olfaction Is Specifically Impaired in Parkinson's Disease.

Olfactory dysfunction (OD) in Parkinson's disease (PD) appears several years before the presence of motor disturbance. Olfactory testing has the potential to serve as a tool for early detection of PD, but OD is not specific to PD as it affects up to 20% of the general population. Olfaction includes an orthonasal and a retronasal components; in some forms of OD, retronasal olfactory function is preserved. We aimed to evaluate whether combined testing components allows for discriminating between PD-related OD and non-Parkinsonian OD (NPOD). The objective of this study is to orthonasal and retronasal olfactory function in PD patients and compare them to a NPOD group and to healthy controls. We hypothesized that this combined testing allows to distinguish PD patients from both other groups. We included 32 PD patients, 25 NPOD patients, and 15 healthy controls. Both olfactory components were impaired in PD and NPOD patients, compared with controls; however, NPOD patients had significantly better orthonasal scores than PD patients. Furthermore, the ratio of retronasal/orthonasal score was higher in PD than in both other groups. In the NPOD group, orthonasal and retronasal scores were significantly correlated; no such correlation could be observed in PD patients. In summary, PD patients seem to rely on compensatory mechanisms for flavor perception. Combined orthonasal and retronasal olfactory testing may contribute to differentiate PD patients from patients with NPOD.

Reversible obstruction of the olfactory cleft: impact on olfactory perception and nasal patency.

BackgroundTemporary disruption of sensory input can be studied relatively easily for vision or hearing by covering the eyes or ears. In contrast, closing the nostrils affects not only the sense of smell, but also the ability to breathe through the nose and humidify and warm inhaled air. We hypothesized that filling the olfactory cleft (OC) with dissolvable nasal dressing (foam) would temporarily block olfaction while respecting nasal airflow.MethodsIn 30 healthy volunteers, the OC was unilaterally obstructed in a back‐to‐front fashion. Orthonasal and retronasal olfactory function were tested before and after foam application. Ratings of odors and subjective nasal patency (SNP) were collected. Peak nasal inspiratory flow (PNIF) was used to measure nasal patency.ResultsFoam was safely applied in every case using minimal instruments. No complications were reported. Orthonasal and retronasal test results decreased significantly in overall participants (all p < 0.0008). Indicating temporary anosmia, 3 subjects reached the lowest possible score for odor‐threshold testing, with corresponding drops in retronasal test scores. PNIF values before and after foam application were not significantly different (p = 0.11). SNP ratings decreased slightly, but not significantly (p = 0.052). Odor‐intensity ratings dropped significantly (all p < 0.05).ConclusionThe OC can be safely obstructed with dissolvable nasal dressing, resulting in a decrease in odor‐intensity and orthonasal and retronasal olfactory function test scores. This procedure may serve as a hyposmia model that maintains normal nasal airflow.

Retronasal olfactory testing using candies sent by post and for screening purposes: a feasibility study.

The olfactory system is able to detect external odours through the orthonasal- and internal odours through the retronasal route. Flavour perception strongly relies on the sense of smell and this back route. In contrast to orthonasal, retronasal olfactory tests (ROT) are less frequently applied, although testing should be recommended for several reasons. The aim of the present investigation was to propose a suitable form of ROT for home-testing (and postal distribution) and evaluate a retronasal screening test. Initially, 111 participants were tested using a 27-item version of the Candy Smell Test (CST). Fifty-four participants performed retesting, of which 25 subjects did so in a home-setting being supplied with professionally packed "candy-chains". Seven candies were chosen by means of hit rate differences in normosmics and severely hyposmics/anosmics. The 7-CST is designed in a non-forced-choice fashion with same seven flavours to choose from. For the 27-item CST both groups (subjects performing home-testing and those performing retesting at the clinic) showed highly significant test-rest-reliabilities. The 7-CST was capable of discriminating healthy from diseased subjects when being tested in 116 healthy subjects and 47 patients suffering from olfactory dysfunction. The CST is suitable for home-testing and postal distribution. The new 7-item CST can be valuable for rapidly revealing anosmics. These findings help in further standardizing ROT, may encourage rhinologists to more routinely evaluate retronasal olfactory abilities and pave the way for larger epidemiologic studies also in regard to food preferences and nutritional behaviour.

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.

Olfactory and Gustatory Functions after Anterior Palatoplasty in Patients with Primary Snoring.

In this study, we investigated the chemical senses (namely, olfaction), the 4 basic tastes, and umami taste in patients who underwent anterior palatoplasty (AP) for primary snoring. Prospective clinical study. Multicenter, tertiary care hospitals. The age range of the 28 participants was 22 to 47 years, and all had been diagnosed with primary snoring by polysomnography. Orthonasal and retronasal olfactory testing was performed using the respective "Sniffin' Sticks." Tests for the 4 basic tastes (sweet, sour, salty, and bitter) and umami were performed before and 6 months after AP. The changes between the preoperative and postoperative results for the 4 basic tastes, which were applied to the anterior tongue region, were not significant. Retronasal olfactory function improved significantly 6 months after AP (P = .007). After AP, umami scores for the soft palate but not those of the anterior and posterior tongue decreased significantly (P = .001). Patients scheduled for AP should be properly informed about potential postoperative taste and flavor changes. They should also be warned of a possible loss of appetite due to a postoperative decrease in the umami taste sensation of the soft palate.

The evaluation of olfactory function in individuals with chronic halitosis.

Halitosis and olfactory dysfunction may disrupt an individual's quality of life remarkably. One may ask whether halitosis has effects on olfactory functions or not? Thus, the aim of this study was to evaluate the olfactory abilities of subjects with chronic halitosis evaluated using the measurements of volatile sulfur compounds. This study was carried out in 77 subjects, with a mean age of 40.1±13.3 years, ranging from 18 to 65 years. Forty-three participants were diagnosed as halitosis according to the gas chromatography results and constituted the halitosis group. Also, a control group was created from individuals without a complaint of halitosis and also who had normal values for volatile sulfur compounds. Each subject's orthonasal olfactory and retronasal olfactory functions were assessed using "Sniffin' Sticks" and retronasal olfactory testing. The results showed that odor threshold scores were lower in participants with halitosis compared with controls. Also, hyposmia was seen more common in the halitosis group than in controls. Moreover, a significant negative correlation was found between odor threshold scores and volatile sulfur compounds levels, particularly with hydrogen sulfide and dimethyl sulfide levels. The results suggest that the chronic presence of volatile sulfur compounds may have a negative effect on olfactory function.

Clinical assessment of olfactory functions in children who underwent adenotonsillectomy during pre- and post-operative period

ObjectiveThe aim of this study was to investigate the changes of both ortho- and retronasal olfactory function in children who underwent adenotonsillectomy (AT) operation due to infectious and/or obstructive adenotonsillar disease. Material and methodsA total of 25 children with adenotonsillar disease are included in the study; the children were followed for 6 months in the conducted clinics and underwent AT operation. An age- and sex-matched control group was constituted with 25 healthy children free of adenotonsillar disease. Adenoid and tonsillar hypertrophy was graded according to the subjective size scales. Each subject’s orthonasal and retronasal olfactory functions were assessed using odor identification test and retronasal olfactory testing. These tests were performed once, at the beginning of the study, for the control group and performed twice, at the beginning of the study and the third month follow-up, for the disease group. Parents of children in the adenotonsillar disease group filled out a visual analog scale to evaluate the children’s appetite at the same time with olfactory testing. ResultsThe current investigation produced four major findings: (1) both ortho- and retronasal olfactory abilities of participants were improving following AT operation, (2) adenoid hypertrophy had a significant negative effect on both ortho- and retronasal olfaction, whereas tonsil hypertrophy had significant negative effect only on the retronasal olfactory score, (3) retronasal olfaction was found to be more affected by the adenoid size than the orthonasal, as shown with correlation analysis, and (4) the increase in appetite of children after AT operation had been specified by parents. ConclusionsChildren with adenotonsillar disease have increased olfaction abilities, namely ortho- and retronasal olfactory function following AT operation. In addition, retronasal olfactory function, an important component of flavor, seems to be more affected than orthonasal function. These results also explain the increased appetite of operated children.

Grade 4 tonsillar hypertrophy associated with decreased retronasal olfactory function: a pilot study

Tonsillar hypertrophy is common in children, but it can also be present in adults. Enlarged tonsils, a significant anatomical barrier, may affect the flow of odor molecules from the oral cavity to the nasal passages, which has not yet been studied. Thus, we aimed to investigate the mass effect of palatine tonsillar hypertrophy on retronasal olfaction. This study was carried out in 146 subjects, with a mean age of 22.1 ± 2.2 years, ranging 20-29 years. An oropharyngeal examination of the participants was completed, and tonsillar hypertrophy was graded according to the subjective tonsil size scale. The participants were divided into four groups according to their tonsil size grading; then, each subject's orthonasal olfactory and retronasal olfactory functions were assessed using "Sniffin' Sticks" and retronasal olfactory testing. There were no differences observed between the groups in terms of age, gender, cigarette smoking, or alcohol consumption. In addition, there was no difference between the groups in terms of "Sniffin' Sticks" subtests and TDI scores. It was determined that the retronasal olfactory scores of the participants with grade 4 tonsil size were significantly lower than the retronasal olfactory scores of the participants with grade 1 tonsil size. The current investigation demonstrates that grade 4 tonsillar hypertrophy has significant negative effects on the retronasal route of olfactory sensing, when compared with grade 1 tonsillar hypertrophy.

The effect of obstructive sleep apnea on olfactory functions

The aim of this study was to investigate the effect of obstructive sleep apnea (OSA) on the parameters of olfactory functions (odor threshold, odor discrimination, and odor identification tests) for orthonasal olfaction, retronasal olfactory testing, and olfactory bulb (OB) volumes. Prospective clinical study. This study was carried out in 78 volunteers between the ages of 20 and 60 years. The mean age of the patients was 46 ± 10.1 years. Patients were divided into three groups according to polysomnography results: 1) a control group, 2) a mild to moderate OSA group, and 3) a severe OSA group. Clinical features of the participants were evaluated with the Epworth Sleepiness Scale. Orthonasal and retronasal olfactory testing were performed with Sniffin' Sticks olfactory testing and retronasal olfactory testing, respectively. Olfactory bulb volumes were measured by planimetric manual contouring on magnetic resonance imaging (MRI). The current investigation produced four major findings: 1) The apnea-hypopnea index had a significant and strong negative correlation with odor threshold scores and odor discrimination scores; 2) The apnea-hypopnea index was significantly negatively correlated with odor identification score and both right and left OB volumes; 3) retronasal olfactory scores were not significantly affected by OSA; and 4) continuous O2 saturation had a significant positive correlation on orthonasal olfactory functions, particularly the odor threshold and discrimination scores. This study demonstrated that OSA had significant negative effects on all orthonasal olfactory tasks, especially on threshold and discrimination. MRI also revealed volumetric shrinkage of OB volumes.

The Effect of Anatomic Clearance Between Tongue and Soft Palate on Retronasal Olfactory Function

Research shows that odorants travel to the olfactory receptors by two routes. Oral conditions, mouth movements, mastication, and swallowing are known to influence the perception of retronasal stimuli. The dimension of the anatomical clearance between the soft palate and tongue might affect the retronasal olfaction because retronasal olfaction is only possible when the soft palate–tongue barrier is opened. Therefore, in this present study, our aim is to evaluate the effect of the anatomical clearance between tongue and soft palate on retronasal olfactory function. After rating the mallampati score for the classification of the clearance between tongue and soft palate, the “Sniffin’ Sticks” test for orthonasal olfaction and retronasal olfactory testing were performed. The study was carried out on 276 subjects, and the mean age of the participants was 27 years ranging from 19 to 53 years. The participants were divided into two groups: Group 1 included participants with mallampati Class 1 and 2 scores; Group 2 included participants with mallampati Class 3 and 4 scores. This study clearly shows that the dimensional differences in the anatomical clearance between the soft palate and tongue had no effects on retronasal olfaction.

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.

Effects of rasagiline on olfactory function in patients with Parkinson's disease

Impairment of olfactory function is a well recognized nonmotor manifestation of Parkinson’s disease(PD). The aim of this investigation was to determine if the MAO-B inhibitor rasagiline can improve olfaction in PD patients. Thirty-four PD patients participated in this single-center, prospective, randomized, controlled,double-blind study. Seventeen patients were randomly assigned to rasagiline and 17 patients to placebo. Orthoand retronasal olfactory testing and recording of event related potentials were performed before and after 120 days of rasagiline versus placebo intake. When comparing olfactory score differences between baseline and after 120 days between the 2 groups, the level of significance was not reached. The primary end point of the study was not reached, and therefore, a specific effect of rasagiline on olfactory function in PD could not be demonstrated.

Prognostic Value of Olfactory Bulb Volume Measurement for Recovery in Postinfectious and Posttraumatic Olfactory Loss

Several prognostic factors influencing the recovery from olfactory dysfunction have been described. The aim of this study was to investigate whether olfactory bulb volume could be used as a new predictor of olfactory recovery in postinfectious and posttraumatic olfactory loss. Cohort study; Level of evidence, 4. Setting Tertiary university clinic, department of otolaryngology. A cohort of 60 patients with postinfectious (n = 28) and posttraumatic olfactory loss (n = 32) was investigated. Assessment of olfactory function was performed using orthonasal (Sniffin' Sticks test) and retronasal psychophysical olfactory tests, at the time of the diagnosis (t1) and 15 months later (t2). All patients were examined on 3 tesla magnetic resonance imaging, and the olfactory bulbs volume was assessed using planimetric contouring at the time of the diagnosis (t1). Recovery rate was 25% in patients with posttraumatic olfactory loss and 36% in patients with postinfectious olfactory loss. There was a correlation between both orthonasal and retronasal olfactory testing and the initial measurement of the total olfactory bulb volume. In addition, we observed a significant correlation between changes in olfactory functions and initial measurement of the total olfactory bulb volume, with larger volumes relating to higher improvement of olfactory function. Finally, we found that none of the patients with a total olfactory bulb volume of 40 mm(3) or less exhibited recovery of olfactory function. Olfactory bulb volume seems to be a predictor of olfactory recovery in patients with postinfectious and posttraumatic olfactory loss.