Purpose of Review Olfactory dysfunction dramatically impairs quality of life with a prevalence of 20% in the general adult population. Psychophysical olfactory testing has been widely used to evaluate the ability to smell due to its validated utility and feasibility in clinic. This review summarizes the current literature regarding psychophysical olfactory testing and the clinical relevance of the olfactory testing with different components. Furthermore, the review highlights the diagnosis and treatment value of olfactory subtests in patients with olfactory dysfunction. Recent Findings With the accumulation of studies of psychophysical olfactory testing in olfactory disorders, the clinical relevance of olfactory testing with different components is expanding. Different olfactory domains present with distinct olfactory processing and cortical activity. Psychophysical assessment of olfaction with three domains reveals different levels of olfactory processing and might assist with analyzing the pathophysiologic mechanism of the various olfactory disorders. Furthermore, olfactory thresholds provided the largest amount of non-redundant information to the olfactory diagnosis. Sinonasal olfactory dysfunction and non-sinonasal-related olfactory dysfunction are emerging classifications of smell disorders with certain characteristics of olfactory impairment and different responses to the therapy including steroids, sinus surgery, and olfactory training. Summary These recent advancements should promote the understanding of psychophysical olfactory testing, the association between individual subcomponents and neurophysiological processes, and pave the way for precision assessment and treatment of the olfactory dysfunction.

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Clinical Implications of Psychophysical Olfactory Testing: Assessment, Diagnosis, and Treatment Outcome

Background Symptoms after Coronavirus Disease (COVID-19) infection affect the quality of life of its survivor especially to the special senses including olfactory function. It is important to prevent the disability at an earlier stage. Vaccination as key prevention has been proven to be effective in reducing symptomatic disease and severity. However, the effects of vaccination on post COVID symptoms have not been evaluated. This study aimed to evaluate the possible protection of full vaccination and the occurrence of post-COVID olfactory dysfunction, specifically anosmia, and hyposmia in patients who were diagnosed with COVID-19. Method A longitudinal analysis using the retrospective cohort of the Indonesian patient-based Post-COVID-19 survey collected from July 2021 until December 2021, involving COVID-19 Patients confirmed by Real-Time Polymerase Chain Reaction (RT-PCR) and/or Antigen test. Variables including demography, comorbidities, health behavior, type of vaccine, symptoms, and treatment were collected through an online questionnaire based on the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS). Participants were matched (1:1) using propensity matching score into two exposure statuses, infected 1)>14 days of full vaccination and 2)<14 days or incomplete or unvaccinated. The olfactory dysfunction was assessed two weeks and four weeks after negative conversion with PCR using a self-measured olfactory questionnaire (MOQ). The Generalized Estimating Equation (GEE) was performed to assess the effect of full vaccination on post-COVID-19 olfactory dysfunction. The Receiver Operating Characteristic determined the sensitivity and specificity of the cutoff value of the days from fully vaccinated to diagnosis and the olfactory dysfunction. Results A total of 442 participants were extracted from the cohort and inoculated with the inactivated viral vaccine (99.5%). The prevalence of olfactory dysfunction in two weeks was 9.95% and 5.43% after four weeks. Adjusted by other variables, people who were infected >14 days after being fully vaccinated had a 69% (adjusted Odds Ratio / aOR 0.31 95% CI 0.102-0.941) probability of developing olfactory dysfunction. Longer days of fully vaccinated to infection are associated with increased risk (aOR 1.012 95% CI 1.002-1.022 p-value 0.015). A cut-off of 88 days of full vaccination-to-diagnosis duration has Area Under Curve (AUC) of 0.693 (p=0.002), the sensitivity of 73.9%, and specificity of 63.3% in differentiating the olfactory dysfunction event in two weeks after COVID-19 with a crude odds ratio of 4.852 (95% CI 1.831-12.855 p=0.001) Conclusion After 14 days of full vaccination, the protective effect could reduce the chance of post-COVID olfactory dysfunction although a longer full vaccination-to-diagnosis duration increases the risk. It is important to consider a booster shot starting from 89 days after the last dose in those who received the inactivated viral regimen.

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Effect of full vaccination and post-covid olfactory dysfunction in recovered covid-19 patient. a retrospective longitudinal study with propensity matching.

To investigate effectiveness of olfactory training (OT) in COVID-19 patients with persistent olfactory dysfunction (OD). From March 2020 to March 2022, COVID-19 patients with OD were prospectively followed in three European medical centers for a period of 18 months. A standardized OT protocol were recommended to patients. Patient-reported outcome questionnaires and psychophysical evaluations were used to evaluate olfaction at baseline, 6, 12, and 18 months after the start of OT. The evolution of olfactory outcome was compared according to the adherence to the OT protocol. Fifty-seven patients completed the evaluations. Thirty-two patients fully adhered to the OT, while 25 did not adhere. The psychophysical scores significantly improved from baseline to 6-month post-infection in both groups. In the OT group, the psychophysical scores continued to significantly improve from 6 to 12 months after the start of OT (p = 0.032). The mean duration of OT was 15.4 weeks. The mean delay of patient recovery perception was comparable between groups (27.4 weeks). The occurrence of cacosmia (35.1%) and parosmia (43.9%) throughout the follow-up period was comparable between groups. There proportion of phantosmia was higher in training (34.4%) compared with no-OT (16.0%; p = 0.007) group. The baseline Sniffin’Sticks tests was positively associated with the 6-month Sniffin’Sticks tests (rs = 0.685; p < 0.001) and negatively associated with the time of recovery (rs = − 0.369; p = 0.034). The adherence to an OT protocol was associated with better mid-term improvement of psychophysical scores. Future large-cohort randomized-controlled studies are needed to confirm the effectiveness of OT in COVID-19 patients. 

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Effectiveness of olfactory training in COVID-19 patients with olfactory dysfunction: a prospective study

Persistent olfactory dysfunction is a major concern post-COVID-19, affecting up to 5% of all patients. Different therapeutic options, including mometasone nasal spray, have been recommended, only some of which have been validated for post-COVID-19 olfactory dysfunction. In this study we psychophysically assessed the effect of intranasally applied mometasone furoate on the recovery of olfaction. The spray was applied with a long applicator so that the olfactory cleft could be reached effectively. After olfactory dysfunction had been confirmed psychophysically using Sniffin’ Sticks, patients were randomly assigned to two different treatment arms: the study group (n = 40) underwent olfactory training and intranasal administration of mometasone furoate twice daily, whereas the control group (n = 46) performed olfactory training only. After a study duration of three months, psychophysical testing of olfaction was repeated using Sniffin’ Sticks. We found no benefit of an additional topical administration of mometasone furoate compared to olfactory training alone. These results psychophysically confirm two previous studies which were based on patients’ subjective self-ratings. Our findings are in contrast to current recommendations for the management of olfactory dysfunction post-COVID-19, which might have to be adapted accordingly.

https://www.mdpi.com/2075-1729/12/10/1483/pdf?version=1664009759

Topical Administration of Mometasone Is Not Helpful in Post-COVID-19 Olfactory Dysfunction

The questionnaire of olfactory disorder-negative statements (QOD-NS) is a valid and reliable instrument for assessing the olfactory-specific quality of life. This study aimed to explore the association between the QOD-NS and objective olfactory metrics (including objective olfactory cleft assessment) and then evaluate the predictive significance of the QOD-NS for olfactory loss in Chinese patients with chronic rhinosinusitis (CRS).A total of 70 patients with CRS were enrolled in the study. Olfaction was assessed with Sniffin' Sticks. The olfactory cleft was assessed by the sinus CT scan and nasal endoscopy (the Lund-Mackay olfactory cleft scale, LM-OC and olfactory cleft endoscopy scale, OCES). The QOD-NS and its short version were utilized to assess the patient-reported olfaction. The predictors associated with olfactory loss were analyzed by the logistic regression analysis. The optimal cutoff points of the predictors were determined by the receiver-operating characteristic curves and the Youden index.The TDI score in patients with CRS significantly correlated with the QOD-NS (r = - 0.755, P < 0.001), OCES (r = - 0.520, P < 0.001), LM-OC (r = - 0.615, P < 0.001). After adjusting for patient demographics and comorbidities, QOD-NS was significantly associated with olfactory dysfunction [odds ratio (OR) = 1.243; P = 0.001] and anosmia in patients with CRS (OR = 1.838; P = 0.006). Furthermore, the QOD-NS significantly correlated with the LM-OC (r = 0.610, P < 0.001), and the OCES (r = 0.464, P < 0.001) in patients with CRS. The QOD-NS had the highest predictive value for olfactory dysfunction (optimal cutoff = 10.5; Youden index = 0.635; area under the curve = 0.861) and anosmia (optimal cutoff = 20.5; Youden index = 0.790; area under the curve = 0.928) in patients with CRS.The QOD-NS showed high validity and correlated well with objective olfactory metrics and olfactory cleft assessment in patients with CRS. The QOD-NS was a reliable predictor for olfactory dysfunction and anosmia in patients with CRS, which may aid in the fast screening of olfactory loss in the clinic. 

/pdf/predictive-significance-of-the-questionnaire-of-olfactory-13lwvaxd.pdf

Predictive significance of the questionnaire of olfactory disorders-negative statements for olfactory loss in patients with chronic rhinosinusitis

Background Posttraumatic olfactory dysfunction is a clinical challenge due to refractory characteristics and limited therapeutic options. Olfactory training has been proved to be effective for olfactory dysfunction with varied etiologies. We pooled existing studies to evaluate the effects of olfactory training in patients with posttraumatic olfactory dysfunction. Methods A systematic literature review using PubMed, Embase, Cochrane Library, and Web of Science was conducted to identify studies assessing olfactory change in patients with posttraumatic olfactory dysfunction after olfactory training. Results Of the initial 812 abstracts reviewed, 13 full-text articles were included. Clinically significant results after olfactory training were defined as an improvement of threshold, discrimination, and identification (TDI) score ≥6 or University of Pennsylvania Smell Identification Test (UPSIT) score ≥4. Six studies were included in the meta-analysis, 36.31% (95% confidence interval [CI], 0.28 to 0.45) of posttraumatic patients would achieve clinically significant results after olfactory training with a mean increase of TDI score of 4.61. Conclusion Olfactory training might be a promising modality for the treatment of posttraumatic olfactory dysfunction. More high-quality studies with controls are needed to clarify the effect of olfactory training on total olfactory performance and subcomponents of olfaction.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/alr.22758

Effects of olfactory training on posttraumatic olfactory dysfunction: a systematic review and meta-analysis.

Background: Postviral olfactory dysfunction (PVOD) is a clinical challenge due to limited therapeutic options and poor prognosis. Both steroids and olfactory training have been proved to be effective for olfactory dysfunction with varied etiologies. We sought to perform a systematic review to summarize the evidence of steroids or olfactory training for patients with PVOD. Methods: A systematic literature review using PubMed, Embase, Cochrane Library, and Web of Science was conducted to identify studies assessing olfactory change in patients with PVOD receiving steroid or olfactory training. Results: Of the initial 273 abstracts reviewed, 20 articles with data from 2,415 patients with PVOD were included. Treatments including topical steroids, systemic steroids, classical olfactory training (COT), modified olfactory training (MOT), and olfactory training with steroid were analyzed. Both psychophysical olfactory testing and subjective symptom scores were utilized to assess the olfactory function. The routine use of nasal steroid spray alone during the management of PVOD seems to have no positive effect on olfactory dysfunction. Direct injection of steroid or nasal steroid spray into the olfactory cleft significantly improved the olfactory function in patients with PVOD. Olfactory improvement is greater than that of the natural course of the disease with short-term COT. Patients with PVOD would benefit more from long-term COT (>12 weeks). Treatment duration, various odorants, olfactory training devices, changing the types of odors periodically, different molecular odorants, and different concentrations of odorants tended to increase the efficiency of MOT. Clinically significant improvement after olfactory training was defined as an increase of threshold, discrimination, and identification (TDI) score ≥6. From week 24 to week 36, both COT and MOT groups reached the maximum therapeutic effect regarding the number of participants achieving clinically significant improvement. A combination of local or oral steroids with olfactory training is more efficient than COT only. Conclusion: Olfactory function in patients with PVOD was effectively improved through direct steroid administration in the olfactory cleft, COT, or modification of COT. The addition of topical steroids to COT therapy showed a tendency for greater olfactory improvement in patients with PVOD.

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Steroids and Olfactory Training for Postviral Olfactory Dysfunction: A Systematic Review.

Review of alternative technologies for acetone-butanol-ethanol separation: Principles, state-of-the-art, and development trends

BackgroundNasal sprays with corticosteroids deliver medication to the restricted areas including anterior and inferior parts of the nasal cavity. The fluticasone exhalation delivery system (EDS-FLU...

Effects of Fluticasone Exhalation Delivery System in Patients With Chronic Rhinosinusitis With Nasal Polyps: A Systematic Review.

To address the problem of decoupling arising from weak binding of extrinsic agents to biomass during its conversion to electrocatalysts, we put forward the hot-pressing method by which heterogeneous solids...

Tianhao Huang

Papers

Effects of olfactory training on posttraumatic olfactory dysfunction: a systematic review and meta-analysis.

Steroids and Olfactory Training for Postviral Olfactory Dysfunction: A Systematic Review.

Review of alternative technologies for acetone-butanol-ethanol separation: Principles, state-of-the-art, and development trends

Effects of Fluticasone Exhalation Delivery System in Patients With Chronic Rhinosinusitis With Nasal Polyps: A Systematic Review.

Improving the performance of biomass-based electrocatalysts by means of hot pressing