Olfactory Threshold Test Research Articles

Olfactory dysfunction as an early predictor for post-COVID condition at 1-year follow-up.

Olfactory dysfunction together with neurological and cognitive symptoms are common after COVID-19. We aimed to study whether performance on olfactory and neuropsychological tests following infection predict post-COVID condition (PCC), persisting symptoms, and reduced health-related quality of life. Both hospitalized (N=10) and non-hospitalized individuals (N=56) were enrolled in this prospective cohort study. Participants were evaluated 1-3 months after infection with an olfactory threshold test and neuropsychological tests, which was used as predictors of PCC. A questionnaire outlining persisting symptoms and the validated instrument EuroQol five-dimension five-level for health-related quality of life assessment were used as outcome data 1 year after infection (N=59). Principal component analysis was used to identify relevant predictors for PCC at 1 year. Objectively assessed olfactory dysfunction at 1-3 months post infection, but not subjective olfactory symptoms, predicted post-COVID condition with reduced health-related quality of life (PCC+) at 1 year. The PCC+ group scored more often below the cut off for mild cognitive impairment on the Montreal Cognitive Assessment (61.5%vs. 21.7%) and higher on the Multidimensional Fatigue Inventory-20, compared to the group without PCC+. Our results indicate that objectively assessed, olfactory dysfunction is a predictor for PCC+. These findings underscore the importance of objective olfactory testing. We propose that olfactory screening in the early post-acute phase of COVID-19 infection might identify individuals that are at higher risk of developing long-term health sequalae.

Effect of wearing masks on odor detection and recognition

Background The effect of wearing masks on olfaction remains unclear. Objectives This study aimed to clarify the differences between the effects of no masks, surgical masks, and N95 respirator masks by conducting both identification and threshold olfaction tests. Methods Young, healthy volunteers aged ≥ 18 years and < 30 years without awareness of apparent olfactory disorder were included. All participants filled out a questionnaire on olfaction and completed an acuity smell identification test (Open Essence test) and an olfactory threshold test (T&T olfactometry) while wearing no masks, surgical masks, or N95 respirator masks. Results In the Open Essence tests, the no-mask group score was significantly higher than those of the surgical- and N95-mask groups. Using T&T olfactometry, the median-detection threshold of the no-mask group was significantly lower than that of the surgical-mask group, and the surgical-mask group threshold was significantly lower than that of the N95-mask group. Similar patterns were observed for the median-recognition threshold. Conclusions Wearing masks, especially an N95 mask, reduces the ability to detect and identify odors. This disadvantage should be considered by professionals such as healthcare workers, who require proper olfaction to perform appropriate tasks.

Olfaction evaluation in dogs with sudden acquired retinal degeneration syndrome.

To evaluate olfaction in dogs with sudden acquired retinal degeneration syndrome (SARDS) compared with sighted dogs and blind dogs without SARDS as control groups. Forty client-owned dogs. Olfactory threshold testing was performed on three groups: SARDS, sighted, and blind/non-SARDS using eugenol as the test odorant. The olfactory threshold was determined when subjects indicated the detection of a specific eugenol concentration with behavioral responses. Olfactory threshold, age, body weight, and environmental room factors were evaluated. Sixteen dogs with SARDS, 12 sighted dogs, and 12 blind/non-SARDS dogs demonstrated mean olfactory threshold pen numbers of 2.8 (SD = 1.4), 13.8 (SD = 1.4), and 13.4 (SD = 1.1), respectively, which correspond to actual mean concentrations of 0.017 g/mL, 1.7 × 10-13 g/mL and 4.26 × 10-13 g/mL, respectively. Dogs with SARDS had significantly poorer olfactory threshold scores compared with the two control groups (p < .001), with no difference between the control groups (p = .5). Age, weight, and room environment did not differ between the three groups. Dogs with SARDS have severely decreased olfaction capabilities compared with sighted dogs and blind/non-SARDS dogs. This finding supports the suspicion that SARDS is a systemic disease causing blindness, endocrinopathy, and hyposmia. Since the molecular pathways are similar in photoreceptors, olfactory receptors, and steroidogenesis with all using G-protein coupled receptors in the cell membrane, the cause of SARDS may exist at the G-protein associated interactions with intracellular cyclic nucleotides. Further investigations into G-protein coupled receptors pathway and canine olfactory receptor genes in SARDS patients may be valuable in revealing the cause of SARDS.

Olfactory Threshold Test as a Quick Screening Tool for Cognitive Impairment: Analysis of Two Independent Cohorts.

Olfactory dysfunction appears prior to cognitive decline, and thus it has been suggested to be an early predictor of Alzheimer's disease. However, it is currently not known whether and how olfactory threshold test could serve as a quick screening tool for cognitive impairment. To define olfactory threshold test for screening cognitive impairment in two independent cohorts. The participants are comprised of two cohorts in China, 1,139 inpatients with type 2 diabetes mellitus (T2DM, Discovery cohort) and 1,236 community-dwelling elderly (Validation cohort). Olfactory and cognitive functions were evaluated by Connecticut Chemosensory Clinical Research Center test and Mini-Mental State Examination (MMSE), respectively. Regression analyses and receiver operating characteristic (ROC) analyses were carried out to determine the relation and discriminative performance of the olfactory threshold score (OTS) regarding identification of cognition impairment. Regression analysis showed that olfactory deficit (reducing OTS) was correlated with cognitive impairment (reducing MMSE score) in two cohorts. ROC analysis revealed that the OTS could distinguish cognitive impairment from cognitively normal individuals, with mean area under the curve values of 0.71 (0.67, 0.74) and 0.63 (0.60, 0.66), respectively, but it failed to discriminate dementia from mild cognitive impairment. The cut-off point of 3 showed the highest validity for the screening, with the diagnostic accuracy of 73.3% and 69.5%. Reducing OTS is associated with cognitive impairment in T2DM patients and the community-dwelling elderly. Therefore, olfactory threshold test may be used as a readily accessible screening tool for cognitive impairment.

COVID-19 Induced Enantiopathy to Hyperosmia (P6-10.005)

<h3>Objective:</h3> Pathophysiology behind reduced olfactory ability in hyperosmic individuals. <h3>Background:</h3> COVID-19 infection as an enantiopathy to hyperosmia has not been described. <h3>Design/Methods:</h3> A 63 year-right-handed male presented with hyperosmia of 150% of normal whereby aromas appeared distorted and disgusting. Shortly, he tested positive for COVID-19 which led to a resolution of his hyperosmia. Alcohol Sniff Test scores fluctuated between zero and three (anosmia). Gradually, his smell improved from 80% and 100% of normal. However, post COVID-19 infection, it returned to 130% of normal. <h3>Results:</h3> Neurological abnormalities: Olfactory Testing: Odor Discrimination Memory Test: Total 7/12 (hyposmia). Bilateral Olfactory Threshold Testing to Phenylethyl Alcohol: 3 (hyposmia). Taste Threshold and Suprathreshold Testing: Mild hypogeusia to Sucrose. Ageusia to Hydrochloric acid, urea and propothiocarbamide. Olfactometer Identification Testing: Left nostril: 10 (anosmia), Right nostril: 8 (anosmia). <h3>Conclusions:</h3> The mechanism whereby COVID-19 acts to reduce olfactory ability in normosmic individuals has been postulated as viral involvement of olfactory nerve at olfactory bulb (Lechien, 2020), pathology of sustentacular cells (Zhang, 2021), olfactory receptor site destruction (Xu, 2022) vasculopathy/arteriopathy of cranial nerve or central connections of olfactory nerve (Parry, 2020) or inflammatory response induced destruction of lamina propria and olfactory nerve apoptosis (Lechien, 2020). The same may have incited a reduced olfaction in hyperosmic individuals-such may be under grouped as understanding the pathophysiology of this subject’s hyperosmia. Perceived hyperosmia is often objectively hyposmic: pathology of inhibiting the inhibitory olfactory discharges that result in enhancement of perceived odor (Kalita, 2022). Elimination of hyperosmia reduces functionality of remaining normosmic neurons which then became relatively hyposmic, but were perceived as normal due to lack of the inhibitory factors. Recovery of hyperosmia upon recovery of olfactory function from COVID-19 would be consistent with such a postulation. Of those with preexisting chemosensory dysfunction, query as to impact of COVID-19 on remaining sensory function is warranted. <b>Disclosure:</b> Mrs. Kalita has nothing to disclose. Miss Birwatkar has nothing to disclose. Dr. Hirsch has nothing to disclose.

The effect of nasal surgeries on olfactory functional outcome

Abstract Background: Nasal pathologies can alter the olfactory function there by the quality of life. In this study, we did an olfactory assessment in patients undergoing nasal surgeries, and the preoperative values were compared with the postoperative values. Objective: The objective of the study is to assess the role of nasal surgeries on olfactory functions in patients with nasal pathologies. Materials and Methods: In total, 70 participants undergoing nasal surgeries were subjected to olfactory function assessment using the Modified I smell test, which comprises olfactory threshold testing and odor identification, and the Numerical Rating Scale. Olfactory assessment was done preoperatively, 4th week and 12th week after the surgery. Results: Among 70 cases, 18 were sinonasal polyposis (25.75%), 16 (22.85%) were chronic rhinosinusitis cases, 35 (50%) deviated nasal septum cases and only one (1.4%) bilateral inferior turbinate hypertrophy case. The overall mean preoperative combined olfactory score (COS) value was 16.03 ± 2.55, 18.06 ± 1.68 in the 4th week of the postoperative period, and in the 12th week, it was 17.99 ± 1.83. There was a significant improvement in olfactory function when preoperative COS was compared with postoperative COS in different nasal surgeries. The olfactory impairment in nasal polyposis and chronic rhinosinusitis was more when compared to other nasal pathologies like nasal obstructions due to deviated nasal septum and turbinate hypertrophy. Overall, 91.7% of participants who underwent functional endoscopic sinus surgery (FESS) and 90% of FESS + septoplasty cases showed improvement in olfactory function. Only 50% of septoplasty cases showed improvement. Conclusion: Nasal pathologies are more common among men of the age group 21–30 years. Olfactory impairment in nasal polyposis and chronic rhinosinusitis was more compared to other nasal pathologies like nasal obstructions due to deviated nasal septum. FESS significantly improves the olfactory function in chronic rhinosinusitis and sino-nasal polyposis patients.

Comparison of prevalence and evolution of COVID-19 olfactory disorders in patients infected by D614 (wild) and B.1.1.7. Alpha variant: a brief report.

To investigate the prevalence and the evolution of olfactory disorders (OD) related to coronavirus disease 2019 (COVID-19) in patients infected during the first and the second European waves. From March 2020 to October 2020, COVID-19 patients with OD were recruited and followed over the 12-month post-infection. The following data were collected: demographic, treatments, vaccination status, and olfactory function. Olfaction was assessed with the Olfactory Disorder Questionnaire (ODQ), and threshold, discrimination, and identification (TDI) test. Outcomes were compared between patients of the first wave (group 1: wild/D614G virus) and the second wave (group 2: B.1.1.7. Alpha variant) at 1-, 3- and 12-month post-infection. Sixty patients completed the evaluations accounting for 33 and 27 patients in group 1 and 2, respectively. The 1-month TDI score (23.7 ± 5.3) was significantly lower in group 2 compared to group 1 (29.8 ± 8.7; p = 0.017). Proportion of normosmic patients at 1-month post-infection was significantly higher in group 1 compared to group 2 (p = 0.009). TDI scores only significantly increased from 1- to 3-month post-infection in anosmic and hyposmic patients. Focusing on There was a negative association between the 1-month ODQ and the 1-month TDI (rs = - 0.493; p = 0.012). ODQ was a significant predictor of TDI scores at 3- and 12-month post-infection. The 12-month prevalence of parosmia was 60.6% in group 1 and 42.4% in group 2, respectively. There was no significant influence of oral corticosteroid treatment, adherence to an olfactory training and vaccination status on the olfactory outcomes. Patients of the second wave (Alpha B.1.1.7. variant) reported significant higher proportion of psychophysical test abnormalities at 1-month post-infection than patients infected during the first wave (D614G virus).

Evaluation of olfactory threshold changes in patients treated with rapid maxillary expansion

Aim: Rapid maxillary expansion (RME) provides an orthopedic effect that solves the problem of transverse deficiency of the maxilla. Moreover, it contributes positively to the functioning of the entire nasopharynx by increasing the cross-sectional area and volume of the nasal tract, thus reducing airway resistance. The aim of this study was to evaluate the changes in olfactory threshold after RME treatment of patients with maxillary transverse deficiency. Methodology: Olfactory threshold and identification tests as well as acoustic rhinometry parameter (Volume1, MCA1, Volume2, MCA2) measurements were conducted for 40 patients (11–16 years) before treatment (T0) and 6 months after (T1) rapid maxillary expansion application. Results: A significant improvement was observed when the olfactory threshold values at T0 (0.96 ± 0.07) and T1 (0.79 ± 0.13) (p &lt; 0.001) were compared. A significant improvement was also observed upon comparing the identification test results at T0 (0.63 ± 0.13) and T1 (0.79 ± 0.11) (p &lt; 0.001). The acoustic rhinometry results showed a significant increase in Volume 1, MCA1, Volume 2 and MCA2 in the right and left nasal cavities after treatment (p &lt; 0.001). Conclusion: In this study, acoustic rhinometry showed that nasal cavity area and volume increased in patients who underwent rapid maxillary expansion therapy. Further, the olfactory functions measured by the olfactory threshold test and identification test improved significantly. How to cite this article: Yıldırım M, Erdur EA, Erdur Ö, Metli ŞN. Evaluation of olfactory threshold changes in patients treated with rapid maxillary expansion. Int Dent Res 2022;12(Suppl.1):90-6. https://doi.org/10.5577/intdentres.435 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Mania associated olfactory dysfunction: A comparison between bipolar subjects in mania and remission

ObjectivesThe aim of this study was to assess the olfactory functions of patients with bipolar disorder in manic phase and to compare them to those of bipolar subjects in remission and healthy controls. MethodsWe recruited 96 participants divided in 3 groups: bipolar mania (MB), euthymic bipolar in remission (EB) and healthy controls (HC). All participants underwent an assessment of their olfactory functions using the Sniffin’ sticks threshold and identification tests. Odors' pleasantness, intensity, familiarity and emotion were assessed. All participants were screened for the presence of psychiatric disorder through the MINI questionnaire. Clinical evaluation explored dimensions of mania, depression, anxiety respectively through YMRS, MADRS and STAI scales. Anhedonia was explored through the Chapman physical and social anhedonia questionnaire. ResultsPatients in mania had deficits in identifying positive smells compared to bipolar subjects in remission and to healthy controls (MB < EB < HC; p < 0.001). Hedonic (MB < EB = HC; p < 0.001) and emotional (MB < EB = HC; p < 0.001) ratings of positive smells were lower in patients in manic phase compared to remitted subjects or controls. Mania was associated to higher emotion rating of negative smells compared to remitted subjects and controls (MB > EB = HC; p < 0.001). There was no difference between the 3 groups in the ratings of intensity and familiarity of smells, as well as in the olfactory threshold testing. The 3 groups showed no difference in the identification of negative smells. ConclusionsPatients in manic episodes showed deficits in identifying positive odors. They evaluated these smells as less pleasant and less emotional compared to remitted bipolar subjects and healthy controls. These olfactory dysfunctions may constitute potential indicators of manic state. The persistence of olfactory dysfunction in remission phase (deficit in the olfactory identification of positive odors compared to healthy controls) may constitute a potential trait indicator of bipolarity.

Effects of Nasal Airflow-Inducing Maneuver in Total Laryngectomy Patients Based on Changes to Olfactory Test Results: A Retrospective Study

Introduction: This study aims to retrospectively examine temporal changes in three aspects, i.e., olfactory threshold test, olfactory identification test, and olfactory perception on daily living test, caused by the use of the nasal airflow-inducing maneuver (NAIM). Methods: The olfactory threshold test (Sniffin’ Sticks test), olfactory identification test (Open Essence [OE]), and olfactory perception on daily living test (self-administered odor question; SAOQ) were administered to 46 patients who had undergone a total laryngectomy (NAIM Start group: 17; Using group: 19; and Nonuse group: 10). The tests were immediately performed after the NAIM and again after an average of 8 months. Results: In the NAIM Start group, all olfactory functions significantly improved in the second test compared with the first test (Sniffin’ Sticks test and OE, p < 0.01 for both; self-administered, p < 0.05). Additionally, in terms of the intergroup changes among scores for the Sniffin’ Sticks test and OE, the NAIM Start group showed a significant difference compared with all of the other groups (Start group > Using and Nonuse group, p < 0.01). The NAIM Using group did not exhibit any significant changes. In the NAIM Nonuse group, olfactory identification function was lower in the second test compared with the first test and showed a trend toward a significant difference (OE, p < 0.1). Temporal changes in SAOQ showed a significant increase in all intragroup comparisons. However, there were no significant differences observed in terms of the changes between the groups. Conclusion: The results demonstrated that even in those who were not using NAIM and undergoing olfactory rehabilitation after laryngectomy (NAIM Start group), the subsequent daily use of NAIM and voluntary rehabilitation aided in the recovery of olfactory function to the same level as that in the already using NAIM group. SAOQ results were considered because of the experimenter effect and they appeared to be unrelated to use NAIM. This study showed that in total laryngectomy patients who did not receive olfactory rehabilitation, olfactory identification was reduced.

A comparison between sniffing and blowing for olfactory testing before and after laryngectomy.

Olfactory dysfunction occurs after laryngectomy due to the loss of nasal airflow and inability to sniff. However, the reason for the loss of olfactory function after laryngectomy is unclear on evaluation with sniffing type tests performed individually. It is expected that the sensorineural olfaction remains, and the results of the sniffing test would be negative, while that of the odour-blowing test would be positive. Therefore, the aim of this study was to investigate both tests and prove normal olfaction in the patients. Patients who had undergone laryngectomy were evaluated using the T&T olfactometer for odour-sniffing tests, Jet Stream Olfactometer (JSO) for odour-blowing tests, and visual analogue scale (VAS). Evaluations were performed pre-operatively, and 1month, 6months, and 1-year post-laryngectomy. Thirty-two patients were included in the study. The median recognition thresholds using the T&T and JSO were 1.4 and 2.2 before surgery, 5.8 and 5.4 at 1month, 5.8 and 5.2 at 6months, and 5.8 and 5.0 at 1 year after surgery, respectively. Results of the olfactory threshold test in both T&T and JSO and VAS score were significantly worse after surgery compared to that before laryngectomy (p < 0.05). The degree of increase was significantly smaller with JSO than with T&T (p < 0.05). While we could not prove normal olfaction in patients after laryngectomy, the odour-blowing test was superior to the odour-sniffing test in detecting patients with residual olfaction. Simply blowing a scent is insufficient to obtain good olfaction; active airflow is crucial for recognizing odours.

A New Method for a Shorter and Valid Assessment of Olfactory Threshold in Repeated Measurement Designs Based on the Sniffin\u2019 Sticks Test

IntroductionThe Sniffin’ Sticks threshold test is widely used to assess olfactory threshold due to its high reliability and validity. Nevertheless, this test procedure is quite long with an average duration of 10 to 20 min. In study designs that require multiple olfactory threshold tests on short intervals, this could exhaust participants. To counteract this limitation, we developed the informed-four-reversal (INFOUR) short version of the Sniffin’ Sticks threshold test for repeated measurement designs and piloted it in a sample of normosmic participants.MethodsForty-two participants performed the original Sniffin’ Sticks version before being assigned either to the control group that repeated the original version or to the test group that conducted the INFOUR short version.ResultsThe correlation between the original version at T1 and INFOUR at T2 was r = .75 and did not differ significantly from the retest reliability of the original version. Compared to the original version, the INFOUR took 42% less time to perform.ConclusionThe INFOUR leads to a significant time saving, while maintaining good validity.ImplicationsTherefore, this approach has the potential to be a useful tool for study protocols with repeated olfactory threshold measurements. In particular, when research protocols are time intensive or testing needs to the shortened, because the interventional effects are short or subtle.

Olfaction in patients with Parkinson\u2019s disease: a new threshold test analysis through turning points trajectories

Olfactory deficit is a widely documented non-motor symptom in Parkinson’s disease (PD). Abnormal turning points trajectories through olfactory threshold testing have been recently reported in patients with olfactory dysfunction, who seem to adapt faster to olfactory stimuli, but data on PD patients are lacking. The aim of this study is to perform olfactory threshold test and explore the turning points trajectories in PD patients in comparison to normal controls. We recruited 59 PD patients without dementia, and no conditions that could influence evaluation of olfaction and cognition. Sixty healthy subjects served as controls. Patients and controls underwent a comprehensive olfactory evaluation with the Sniffin’ Sticks extended test assessing threshold, discrimination and identification and a full neuropsychological evaluation. Besides, threshold test data were analyzed examining all the turning points trajectories. PD patients showed a different olfactory threshold test pattern, i.e., faster olfactory adaptation, than controls with no effect of age. Normosmic PD patients showed different olfactory threshold test pattern, i.e., better threshold score, than normosmic controls. Visuospatial dysfunction was the only factor that significantly influenced this pattern. Olfactory threshold trajectories suggested a possible adaptation phenomenon in PD patients. Our data offered some new insights on normosmic PD patients, which appear to be a subset with a specific psychophysical profile. The analysis of the turning points trajectories, through an olfactory threshold test, could offer additional information on olfactory function in PD patients. Future larger studies should confirm these preliminary findings.

A novel olfactory threshold test for screening cognitive decline among elderly people.

Olfactory impairment is associated with dementia and is a potential early biomarker of cognitive decline. We developed a novel olfactory threshold test called Sniff Bubble using rose odor-containing beads made with 2-phenylethyl alcohol. We aimed to define cut-off scores for this tool to help identify cognitive decline among elderly people. In total, 162 elderly people (mean age ± SD: 73.04 ± 8.73 years) were administered olfactory threshold and neurocognitive tests. For analyses, we divided the participants into two groups based on cognitive functioning, namely cognitive decline (n = 44) and normal cognition (n = 118) groups. The Sniff Bubble and YSK olfactory function test for olfactory threshold and the Structured Clinical Interview for DSM-5 Disorders-Clinician Version and Korean version of the Consortium to Establish a Registry for Alzheimer’s Disease assessment packet for neurocognitive functioning were used. We used K-means cluster analyses and receiver operating characteristic (ROC) analyses to identify the most appropriate cut-off value. We established a positive correlation between the Sniff Bubble and neurocognitive function test scores (r = 0.431, p < 0.001). We defined the cut-off score, using the ROC curve analyses for Sniff Bubble scores, at 3 and higher with an area under the curve of 0.759 (p < 0.001). The Sniff Bubble test can adequately detect cognitive decline in elderly people and may be used clinically as the first step in the screening process.

Impaired olfactory neural circuit in patients with SLE at early stages.

To investigate the changes of olfactory function and odor-induced brain activation in patients with systemic lupus erythematosus (SLE) at early stages compared with healthy controls. Olfactory function and odor-induced brain activation in 12 SLE patients at early stages and 12 age, gender and education matched healthy controls were evaluated using olfactory behavior test and odor-induced task-functional magnetic resonance imaging (task-fMRI). No significant differences in olfactory behavior scores (including olfactory threshold, olfactory identification, and olfactory memory) were found in the patients with SLE at early stages compared with the healthy controls, while significantly decreased odor-induced activations in olfactory-related brain regions were observed in the patients. In the SLE group, the patients with better performance in the olfactory threshold test had significantly lower levels of anti-dsDNA antibody. The current study demonstrated that significant alterations in odor-induced brain activations occurred prior to measurable olfactory decline in SLE at early stages, which provided a new method for early diagnosis of olfactory dysfunction in SLE.

Effect of Chronic Kidney Disease on Olfactory Function: A Case-Control Study.

Olfactory function of patients with chronic kidney disease (CKD) has been found to be defective, and patients are often unaware of it. This predisposes them to malnutrition with consequence on health recovery and quality of life. To assess the olfactory function and determine the pattern of olfactory dysfunction in patients with CKD attending the University College Hospital, Ibadan. This was a prospective, hospital-based case-control study of adult patients with CKD. The control group were age- and sex-matched individuals without CKD. Olfactory threshold (OT), odor discrimination (OD), and odor identification (OI) tests were carried out in participants using the "Sniffin Sticks." There were 100 patients with CKD and 100 healthy controls, age ranges between 19 to 86 years (mean ± SD = 46.3 ± 13.9 years) and 20 to 85 years (mean ± SD = 43.4 ± 14.9 years), respectively. There was no statistically significant difference between cases and control gender distribution (P = .57). The mean olfactory scores were significantly lower among the cases than control, OI 11.2 ± 2.3 and 13.1 ± 1.2 (P < .001), OD 8.5 ± 2.4 and 10.9 ± 1.5 (P < .001), OT 6.4 ± 2.5 and 9.6 ± 1.9 (P < .001), and threshold discrimination and identification 26.0 ± 5.7 and 33.6 ± 3.3 (P < .001), respectively. Prevalent olfactory dysfunction among patients with CKD was 77% (hyposmia 72%, anosmia 5%), and the control was 16% (all hyposmia; P < .001). There was high prevalence of olfactory dysfunction among patients with CKD, and the affectation is more at the central olfactory pathway.

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.

Assessment of Olfactory Function in Children and Adolescents: An Overview.

Valid and reliable tools for assessing olfactory function are necessary for the diagnosis of olfactory dysfunction. Olfactory testing can be challenging in a pediatric population due to shorter attention span, linguistic development, and lower olfactory experience in this age group. The aim of this article is to present an overview about olfactory tests that are suitable for a pediatric population. Publications were included when reporting new developed methods of psychophysical olfactory testing in children or adaptation and applications of existing olfactory tests for a pediatric population. Olfactory tests for all 3 major aspects of olfactory function-olfactory threshold, odor discrimination, and odor identification-were included. Olfactory tests were evaluated regarding test validity, test reliability, normative data, and test availability. The current literature shows that several tests are available to assess olfactory function in children. Especially odor identification abilities in a pediatric population are well examined and understood. Tests for olfactory threshold and odor discrimination are less frequently used. In terms of the abovementioned evaluation criteria, only a few tests met all or 3 of these 4 criteria. Based on the current literature the following tests can be recommended for valid and reliable olfactory testing in children: "U-Sniff" odor identification test, the "Sniffin' Sticks" olfactory threshold test, pBOT-6 olfactory threshold and odor identification test, NIH-Toolbox, and Smell Wheel. Age has to be considered when evaluating olfactory function in children.

The Influence of Cognitive Parameters on Olfactory Assessment in Healthy Children and Adolescents.

Olfactory threshold and odor identification tests are frequently used for assessment of olfactory function in children and adolescents. Whether olfactory test results are influenced by cognitive parameters or sex in children and adolescents is largely unknown. The aim of this study was to investigate the influence of cognition, age and sex on "Sniffin' Sticks" olfactory threshold and "U-Sniff" odor identification performance in a pediatric population. A total of 200 participants between age 6 and 17 years were included. Olfactory function (olfactory threshold and odor identification) was assessed using the "Sniffin' Sticks." In addition, age appropriate cognitive testing was applied. The results of this study indicate that odor identification test performance is positively correlated with age (r = 0.31) and verbal abilities of children (r = 0.24). Olfactory threshold results are only marginally influenced by age (r = 0.18) and are not associated with cognitive test performance. Olfactory assessment using olfactory threshold and "U-Sniff" odor identification testing is suitable for children and adolescents when considering age in the interpretation of test results.

Better Olfactory Performance and Larger Olfactory Bulbs in a Mouse Model of Congenital Blindness.

It is well established that early blindness results in enhancement of the remaining nonvisual sensory modalities accompanied by functional and anatomical brain plasticity. While auditory and tactile functions have been largely investigated, the results regarding olfactory functions remained less explored and less consistent. In the present study, we investigated olfactory function in blind mice using 3 tests: the buried food test, the olfactory threshold test, and the olfactory performance test. The results indicated better performance of blind mice in the buried food test and odor performance test while there was no difference in the olfactory threshold test. Using histological measurements, we also investigated if there was anatomical plasticity in the olfactory bulbs (OB), the most salient site for olfactory processing. The results indicated a larger volume of the OB driven by larger glomerular and granular layers in blind mice compared with sighted mice. Structural plasticity in the OB may underlie the enhanced olfactory performance in blind mice.