TDI Score Research Articles

Comparative analyses of post-infectious olfactory dysfunction between COVID-19 and non-COVID-19 cases

To identify the differences between COVID-19-associated and non-COVID-19-associated olfactory dysfunction (OD), we analyzed demographic and clinical characteristics based on the causative virus (COVID versus non-COVID groups) in patients with post-infectious olfactory dysfunction (PIOD) who underwent the olfactory questionnaire and olfactory function test. Out of 169 patients with PIOD, 99 were diagnosed with COVID-19 (COVID group), while 70 were not (non-COVID group). The COVID group was younger and had a higher percentage of male patients as well as patients with parosmia than the non-COVID group. In the initial olfactory function tests, the TDI, discrimination and identification scores were significantly higher in the COVID group than in the non-COVID group. TDI scores were significantly increased in patients with PIOD after treatment, regardless of the group. The threshold score was significantly increased by 1.38 in the COVID group while the identification score was significantly increased by 2.67 in the non-COVID group. Patients with COVID-19-associated OD were younger in age, tended to be male, had a higher incidence of parosmia, and had better initial olfactory function test results compared to those with non-COVID-19-associated OD. Following treatment, odor detection threshold improved in the COVID group, whereas odor identification improved in the non-COVID group.

Parosmia in patients with post-infectious olfactory dysfunction in the era of COVID-19-associated olfactory impairment.

Alarge number of patients with olfactory impairment are affected by parosmia or phantosmia. This study aimed to examine the demographic and clinical characteristics of parosmia. We performed aretrospective data analysis of patients consulting at our Smell and Taste Outpatient Clinic. Atotal of 297 patients were included (203 women, mean age44.4 ± 13.7years). Olfactory function was quantified using the "Sniffin' Sticks" composite TDI (odor threshold, determination, and identification) score. The presence of qualitative olfactory impairment was assessed trough medical history and aparosmia questionnaire. Most of the patients showed olfactory impairment after an infection with SARS-CoV‑2 (84%) and were diagnosed with parosmia (49%). Patients with parosmia (PAR) (n = 201) were significantly younger compared to the group without parosmia (noPAR; n = 92) (PAR 43.2 ± 13years vs. noPAR 47 ± 15.1 years, p = 0.03) and had aslightly shorter duration of disease, without reaching statistical significance (PAR 10.3 ± 4.9months, noPAR 13.6 ± 37.6 months, p = 0.23). They also had higher TDI scores (PAR 24.3 ± 7points, noPAR 21.4 ± 8.2points, p = 0.003). Patients affected by parosmia were younger and had abetter olfactory function compared to patients without parosmia.

Smell and taste disorders in childhood: Diagnostic challenges and significant impacts on a child's well-being

AimSmell and taste are senses that contribute to a child's overall well-being. Disorders affecting these senses can impact a child's daily life from enjoying meals to detecting potential dangers through scent.The aim of this study is to describe patient characteristics and etiological causes of olfactory (OD) and/or gustatory disorders (GD) in children referred to a smell and taste clinic. Secondly, we aim to suggest a clinical work up. MethodsRetrospective study where data were collected from 57 children who were referred consecutively to the University Clinic for Flavour, Balance, and Sleep; Department of Otorhinolaryngology (ORL), Head and Neck Surgery; Goedstrup Hospital, Denmark, for assessment due to OD/GD from January 2017 to May 2023. ResultsMost of the children had anosmia (60 %), whereas sensation of the basic tastes was intact in all but eight children (16 %). The lowest TDI scores were in children with congenital OD. The underlying etiology was congenital followed by postinfectious mostly related to Covid-19. Picky eating including anorectic traits were seen in 16 % of patients. ConclusionThe focus on smell loss in pediatric population is low, and probably does not adequately reflect either underlying prevalence in this group or the possible consequences on a child's well-being. Moreover, increased awareness of children's smell and taste loss is needed, as it may be associated with eating disturbances.

Adherence to olfactory training improves orthonasal and retronasal olfaction in post-COVID-19 olfactory loss.

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.

The effect of smell training on COVID-19 induced smell loss.

while smell training appears to be effective for post viral smell loss, its effectiveness in COVID-19 induced smell loss is currently not well known. Therefore, we aim to investigate the potential effect of smell training on patients with COVID-19 induced smell loss. we conducted a case-control study with two comparable cohorts. One of which (n=111) was instructed to perform smell training twice daily for 12 weeks, therapeutical adherence was monitored on a daily schedule, while the other cohort (n=50) did not perform smell training. The Sniffin' Sticks Test (SST) was used to objectify participants' sense of smell at baseline and after 12 weeks, reported as a Threshold, Discrimination, and Identification (TDI) score. We also determined the association between therapeutical adherence and the TDI scores. we found a significant difference in psychophysical smell function between patients with COVID-19 induced smell disorders who performed 12 weeks of smell training and those who did not. Median TDI difference between groups was 2.00 However, there was no association between the therapeutical adherence and olfactory function. we discovered a significant moderate difference in psychophysical smell function between patients with COVID-19-induced smell disorders who performed smell training and those who did not, implying a possible advantage of training. However, no relationship was found between therapeutical adherence of smell training and olfactory function.

Maximizing Participation in Olfactory Training in a Sample with Post-COVID-19 Olfactory Loss.

This study aims to highlight the feasibility of an olfactory training program entirely monitored through online media in COVID-19 patients. Classic olfactory training was performed with a sample with olfactory loss due COVID-19 (n = 11). Participants were engaged on a weekly video call in order to improve adherence and collect information regarding the number of correct answers and the individuals' perception of olfactory function. The olfactory status after training was compared to two groups, one composed of participants who contracted COVID-19 but did not report olfactory loss (n = 11) and a sample composed of healthy participants (n = 11). The experimental group showed improvements throughout the training period (TDI score on week 0 was 20.3 (5.6) and 24.6 (4.3) for week 12, and on week 24 was 25.4 (6.2) (F = 5.115, df = 2, 20, p = 0.016), and post hoc tests showed that participants significantly improved their TDI score in W12 compared to W0 (SMD = 0.869, p = 0.041) and in W24 compared to W0 (SMD = 0.859, p = 0.041). The experimental group showed lower scores when compared with both groups, and the no OT COVID-19 group showed lower scores than the healthy control group, even though they did not report olfactory alterations. Findings suggest that the strategies applied to improve adherence were successful since 100% of the sample completed the training adherence, offering a valuable framework for future olfactory training studies.

Knowledge and attitude of traumatic dental injuries in Mongolian schoolteachers

BackgroundTraumatic dental injury (TDI) is a growing public health concern worldwide, and children and adolescents are commonly affected. Because TDI often occurs at school, the response of teachers to these injuries is crucial. However, teachers in various countries have been shown to lack knowledge of effective TDI first-aid response and need an intervention to improve their knowledge. The aim of the study presented here was to ascertain and analyze teachers’ knowledge of and attitude about TDI in Mongolia.Materials and methodsA cross-sectional study of full-time teachers in Mongolia was performed using an online questionnaire (compiled from relevant studies) from September 2022 to December 2022. The questionnaire consists of 47 items and among them 14 were used to assess the teacher’s knowledge, and 5 were for attitude towards TDI. The maximum possible score was 14 points and grouped as follows good, moderate, and poor. T-test, ANOVA test (post-hoc) and linear regression analysis were performed.ResultsThe online survey provided quantitative data from 2821 participants: 28% were elementary school teachers, 29% middle school teachers, and 42% high school teachers. Their mean age was 36.7 ± 9 years, and 2433 (86%) were female. The mean score of the TDI knowledge of the teachers was 5.3 ± 2.1 out of 14. The ANOVA test showed that older (p < 0.01) and more experienced teachers (p < 0.01) had higher scores. Teachers in the eastern (5.46 ± 2.2) and southern (5.49 ± 2.2) provinces had higher mean scores than in the other provinces (p < 0.02). Teachers majored in natural sciences (5.4 ± 2.2) had a higher score than those in the social sciences (5.2 ± 2.1) and difference were significant (p < 0.02). The multiple regression model statistically significantly predicted a one-year increase in experience, the TDI score increased 0.034 (95% CI 0.026, 0.043) unit.ConclusionsThe knowledge regarding TDI and effective first-aid response to such injury is low in teachers in Mongolia. However, the teachers’ attitude about TDI was positive and they wanted to learn and improve their knowledge. Therefore, further education and training programs are advised.

Olfactory dysfunction in patients with type 2 diabetes mellitus.

diabetic complications and olfactory dysfunction (OD) in patients with type 2 diabetes mellitus (T2DM) seem related. This study aims to evaluate the prevalence of OD in T2DM patients and to analyze its relationship with diabetic complications. 130 T2DM patients and 100 comparable controls were enrolled. Olfaction was evaluated using the Extended Smell Test (TDI) and the Italian brief Questionnaire of Olfactory Disorders â€" Brief-IT-QOD. T2DM patients were divided into: "Group 1" patients with no complications, and "Group 2" patients with at least one diabetic complication. Non-parametric tests were used. Machine learning algorithms were applied to explore which variables were most important in predicting the presence of OD in T2DM. The prevalence of OD was significantly higher in Group 2 than in controls (71.4% vs 30%) and in Group 1 (71.4% vs 43.3%). However, when comparing the TDI scores between Group 1 and 2 the only significant difference was found for the discrimination scale and not for the identification and threshold scales. Brief-IT-QOD scores were significantly higher in Group 2 than in controls. The Random Forest and variable importance algorithms highlighted the relevance of LDL, glycated hemoglobin, type of complication (macrovascular) and age in determining OD in T2DM. The last three variables were included in a nomogram for the prediction of OD risk in T2DM. T2DM patients with diabetic complications are more frequently affected by OD. Poor glycemic control, LDL values, age and presence of macrovascular complications are the more important factors in determining OD in T2DM patients.

Periodontitis is associated with impaired olfactory function: Aclinical study.

To explore the association between periodontitis and olfactory disorders. Clinical data were collected from 198 individuals between the ages of 18 and 60 years living in Denmark. The exposure was periodontitis, and the outcome was olfactory function (Threshold, Discrimination, Identification - TDI score), both measured clinically. Covariates included sex, age, education level, income, usage of nasal spray, tongue coating, halitosis, xerostomia, smoking, and history of COVID-19. Structural equation modeling was used to estimate the association between periodontitis and olfactory function. Periodontitis was defined using the AAP/EFP classification and dichotomized into "no" (healthy subjects) and "yes" (Stages I, II, and III). Olfactory function was treated as a one-factor latent variable, including the different olfactory scores. In addition, extra models were performed considering each olfactory component as a separate outcome and the TDI Global Score. The results showed that periodontitis was associated with a lower olfactory function [standardized coefficient (SC) -0.264, 95% CI -0.401, -0.118]. Additionally, periodontitis was also associated with a lower olfactory Threshold (odorant concentration required for detection) (SC -0.207, 95% CI -0.325, -0.089), Discrimination (ability to discriminate between odorants) (SC -0.149, 95% CI -0.270, -0.027), Identification (ability to identify odorants) scores (SC -0.161, 95% CI -0.277, -0.045), and TDI Global Score (SC -0.234, 95% CI -0.370, -0.099). This study suggests that periodontitis is associated with olfactory impairment.

Palmitoylethanolamide and Luteolin for Postinfectious Olfactory Disorders: How Clinically Meaningful Is Its Effect?

The prevalence of post-viral olfactory dysfunction has increased significantly during the COVID-19 pandemic, posing a major challenge for patients and practitioners. While olfactory training (OT) is a common approach to therapy, there has been increasing interest in supplementing therapy with a combination of palmitoylethanolamide (PEA) and luteolin (LUT), which are known for their anti-inflammatory properties. In this study, their efficacy in the treatment of patients with olfactory loss following upper respiratory tract infections, mainly COVID-19, was investigated in an outpatient clinic. Fifty patients with persistent olfactory dysfunction were randomized to two groups: one receiving OT and PEA-LUT, the other OT alone. Olfactory function was evaluated before and after treatment. The study group showed significant improvements in odor discrimination and overall olfactory function (TDI score) after treatment with PEA-LUT and OT, while the control group did not. However, when clinically meaningful improvements were considered, there was no significant difference between the groups. The present study suggests that while PEA-LUT may have the potential to improve olfactory function in post-viral dysfunction, the additional benefit over OT alone may be limited. These results contrast with some previous studies.

Subjective versus Psychophysical Measures of Chemosensory Alterations following COVID-19

Introduction: Olfactory dysfunction is a common symptom of COVID-19. However, subjective perception of olfactory function does not always correlate well with more objective measures. This study seeks to clarify associations between subjective and psychophysical measures of olfaction and gustation in patients with subjective chemosensory dysfunction following COVID-19. Methods: Adults with persistent COVID-19-associated chemosensory disturbance were recruited for a prospective, longitudinal cohort study at a tertiary care institution. Participants provided subjective measures of olfactory and gustatory function and underwent psychophysical assessment using Sniffin’ Sticks olfactory and Monell gustatory tests. Results: Data analysis (n = 65) showed a statistically significant association between subjective and psychophysical measures of olfaction (p < 0.001). For each one-point increase in subjectively-reported olfactory ability, there is, on average, a 0.11 (95% CI: 0.06, 0.16; p < 0.001) point increase in TDI score while adjusting for age at baseline assessment, sex, and follow-up time. For each one-point increase in subjectively-reported olfactory ability, there is, on average, a 0.04 (95% CI: 0.02, 0.06; p < 0.001) point and 0.05 (95% CI: 0.03, 0.07; p < 0.001) point increase in discrimination and identification scores, respectively, when adjusting for age at baseline assessment, sex, and follow-up time. Conclusion: Subjective olfaction shows a mild to moderate association with psychophysical measures, but it fails to comprehensively assess persistent COVID-19-associated chemosensory deficits. The lack of significant association between subjective olfaction and threshold limits the utility of subjective olfaction in tracking recovery. These findings support the push for more widespread psychophysical chemosensory testing.

The Impact of Early Pulmonary Rehabilitation on Dyspnea, Quality of Life, and Symptoms in Moderate to Severe COVID-19 Pneumonia Patients

Introduction: COVID-19 pneumonia leads to dyspnea, persistent symptoms and poor quality of life. Inpatient pulmonary rehabilitation (PR) has limited evidence of effectiveness. Therefore, we aimed to determine the effect of a comprehensive inpatient PR program on dyspnea symptoms and quality of life in patients with COVID-19 pneumonia. Methods: A group pretest-posttest design was conducted in patients with COVID-19 pneumonia. Comprehensive PR was administered during hospitalization. Baseline dyspnea index (BDI), Transitional dyspnea score (TDI), Modified Medical Research Council score (mMRC), and St. George’s Respiratory Questionnaire (SGRQ) were assessed at baseline, 4th week and 12th week after discharge. Results: In total, 28 patients were included (9 with oxygen supplementation, 19 without oxygen supplementation). The mean BDI at baseline was 7.82 ± 2.13. TDI scores at the 4th and 12th weeks were 5.14 ± 1.90 and 6.61 ± 1.59, respectively, with a significant difference observed between the 4th and 12th weeks (p &lt; 0.001). Median mMRC scores at baseline, 4th week, and 12th week were 2(1.25 - 3), 1 (1 - 2) and 1 (0 - 1), respectively, showing a significant improvement between baseline vs 4th week, baseline vs 12th week, and 4th week vs 12th week (p &lt; 0.001). The total SGRQ score exhibited a median (IQR) of 11.34 (7.88 - 8.58) at the 4th week and 6.93 (4.43 - 13.03) at the 12th week, demonstrating a statistically significant improvement (p &lt; 0.001). No adverse events were reported during inpatient PR. Conclusion: Inpatient PR provides a safe and feasible profile, reduces dyspnea symptoms, and improves the quality of life in patients with moderate to severe COVID-19 pneumonia. HIGHLIGHTS COVID-19 pneumonia results in dyspnea and persistent symptoms, impacting quality of life. Early pulmonary rehabilitation, from inpatient to a 12-week outpatient program for moderate and severe cases, is safe and improves dyspnea, quality of life, and patient reported symptoms. GRAPHICAL ABSTRACT

Correlation of Molecular Status with Preoperative Olfactory Function in Olfactory Groove Meningioma.

The study aims to examine the possible correlation between genomic alterations and preoperative olfactory function in patients with olfactory groove meningioma (OGM), due to the frequent presence of olfactory impairment. We utilised next-generation sequencing to analyse samples from 22 individuals with OGM in order to detect driver mutations. Tumour morphology was assessed using preoperative imaging, whereas olfactory function was examined using Sniffin' Sticks. In a study of 22 OGM patients, mutations were as follows: 10 with SMO/SUFU, 7 with AKT1, and 5 as wild type. Planum sphenoidale hyperostosis (PSH) was present in 75% of patients, showing significant variation by mutation (p = 0.048). Tumour volumes, averaging 25 cm3, significantly differed among groups. PSH negatively impacted olfaction, notably affecting odour threshold, discrimination, identification, and global olfactory performance score (TDI) (p values ranging from <0.001 to 0.003). Perifocal oedema was associated with lower TDI (p = 0.009) and altered threshold scores (p = 0.038). Age over 65 and female gender were linked to lower thresholds and discrimination scores (p = 0.037 and p = 0.019). The study highlights PSH and perifocal oedema's significant effect on olfactory function in OGM patients but finds no link between olfactory impairment and tumour mutations, possibly due to the small sample size. This suggests that age and gender affect olfactory impairment. Additional research with a larger group of participants is needed to explore the impact of OGM driver mutations on olfactory performance.

Does experience of music enhance olfaction: music as a potential nutrition intervention?

Olfaction, the sense of smell, is under recognised and underappreciated despite being vital in wellbeing. It confers a major influence on the feeding process being the major contributor of flavour and has a direct involvement in the cephalic phase responses. Along with its influence on food and nutrition, olfaction is directly associated with cognitive function and impacts social communication and safety(1). Loss of olfactory acuity, commonly occurring in aging and frailty, significantly influences dietary behaviour and food selection(2). Unlike the senses of vision and audition, interventions are lacking. We propose in a proof-of-concept that crossmodal integration of olfaction and audition could inhibit olfactory decline in lifelong musicians through encouraging neuroplasticity of the olfactory brain centres. Ethical approval was obtained from The University of Adelaide Human Research Ethics Committee. Male musicians with a lifetime experience of music (ME) and naïve non-musicians (NM) aged 55 years and over were recruited through music organisations and controls through the Australian Men’s Shed network. The initial target sample size was twenty per cohort. Olfactory acuity was assessed with Sniffin’ sticks® (Odofin, Groningen, The Netherlands), a well validated system of a battery of three tests regimes. Sniffin’ sticks represent ‘felt tipped pens’ impregnated with odourants presented 20mm below the nose of participants who were then prompted to ‘sniff’. Assays determined participant ‘Threshold’, ‘Discrimination’ and ‘Identification’ of test odours (3). Measurement of Threshold and Discrimination were undertaken in triplet fifteen seconds apart with eyes closed; measurement of Threshold being conducted in an ascending ‘staircase’ to detect lowest odour concentration detectable, whereas measurement of Discrimination selected the ‘odd-man-out’ of a triplet comprising two identical and one different odour. Measurement of Identification, with eyes open, selected the odour of a single ‘pen’ from a prompt list of four. All tests demanded selection. Each of the test batteries were scored out of sixteen along with total aggregate of Threshold, Discrimination, and Identification (TDI). Twenty-six participants completed the study (18 ME and 8 NM); numbers were limited owing to active COVID-19. Mean and standard deviations (SD) of Threshold, Discrimination, Identification and TDI were derived and compared between groups using ‘t’-test. For ME, Threshold, Discrimination, and Identification values were 6.2 (SD ± 3.7), 10.6 (SD ± 1.9), and 12.9 (SD ± 1.6). The respective values for NM were 5.0 (SD ± 2.3), 8.8(SD ± 2.9), and 10.8 (SD ± 2.5). The ME group showed a significantly higher Discrimination (p = 0.164). Significant differences were not seen for Threshold, Identification, and overall TDI scores, however the small sample size may have accounted for this. Based on this proof-of-concept, further exploration of music is warranted as an intervention to enhance olfactory acuity to potentially improve the intake of food and nutrition, and enrich pleasure of eating and drinking, and quality of life.

Persistent COVID-19 parosmia and olfactory loss post olfactory training: randomized clinical trial comparing central and peripheral-acting therapeutics

PurposeAlthough COVID-19 anosmia is often transient, patients with persistent olfactory dysfunction (pOD) can experience refractory parosmia and diminished smell. This study evaluated four putative therapies for parosmia in patients with chronic COVID-19 olfactory impairment.MethodsAfter screening nasal endoscopy, 85 patients (49 female, 58%) with pOD and treatment-refractory parosmia were randomized to: (1) ultramicronized palmitoylethanolamide and luteolin + olfactory training (OT) (umPEALUT group, n = 17), (2) alpha-lipoic acid + OT (ALA group, n = 21), (3) umPEALUT + ALA + OT (combination group, n = 28), or 4) olfactory training (OT) alone (control group, n = 23). Olfactory function was assessed at baseline (T0) and 6 months (T1) using a parosmia questionnaire and Sniffin’ Sticks test of odor threshold, detection, and identification (TDI). Analyses included one-way ANOVA for numeric data and Chi-Square analyses for nominal data on parosmia.ResultsThe umPEALUT group had the largest improvement in TDI scores (21.8 ± 9.4 to 29.7 ± 7.5) followed by the combination group (19.6 ± 6.29 to 27.5 ± 2.7), both p < 0.01. The control and ALA groups had no significant change. Patients in the combination and umPEALUT groups had significantly improved TDI scores compared to ALA and control groups (p < 0.001). Rates of parosmia resolution after 6 months were reported at 96% for combination, 65% for control, 53% for umPEALUT and 29% for ALA (p < 0.001). All treatment regimens were well-tolerated.ConclusionsumPEALUT and OT, with or without ALA, was associated with improvement in TDI scores and parosmia, whereas OT alone or OT with ALA were associated with little benefit.

Impact of post-COVID-19 olfactory disorders on quality of life, hedonic experiences and psychiatric dimensions in general population

Background and objectiveOlfactory disorders in COVID-19 impact quality of life and may lead to psychological impairments. Prevalence ranges from 8 to 85%, persisting in about 30% of cases. This study aimed to evaluate the 6-month post-COVID-19 impact on quality of life, hedonic experiences, anxiety and depression due to olfactory disorders. Additionally, it sought to compare psychophysical tests and self-perceived olfactory evaluations.MethodsA prospective, longitudinal study was conducted over baseline (T0) and 6 months (T1) on individuals with persistent olfactory disorders post-COVID-19 for more than 6 weeks. Psychophysical tests employed the Sniffin’ Sticks Test® (TDI score), and self-perceived olfactory evaluation used a Visual Analogue Scale. Quality of life was assessed with an Olfactive Disorder Questionnaire and the French version of the Quality of Life and Diet Questionnaire. Hedonic experiences were gauged using the Snaith-Hamilton Pleasure Scale, while anxiety and depression dimensions were measured by The State-Trait Anxiety Inventory, The Post Traumatic Stress Checklist Scale, and Hamilton Rating Scale for Depression. Participants were classified into the “normosmic group” (NG) and the “olfactory disorders group” (ODG) at T0 and T1 based on the TDI score.ResultsWere included 56 participants (58.93% women, 41.07% men) with a mean age of 39.04 years and a mean duration of post-COVID-19 olfactory disorders of 5.32 months. At T1, ODG had a significantly lower quality of life and hedonic experiences than NG. No significant differences in anxiety and depression dimensions were observed between groups. At T0, psychophysical tests and self-perceived olfactory evaluations were significantly correlated with quality of life and hedonic experiences in both groups. At T1, self-perceived olfactory evaluation in NG correlated significantly with quality of life, hedonic experiences, anxiety and depression dimensions, whereas ODG only correlated with hedonic experiences.ConclusionIndividuals with persistent post-COVID-19 olfactory disorders after six months demonstrated compromised quality of life and hedonic experiences. Self-perceived olfactory evaluation played a more significant role in influencing quality of life and the dimension of anxiety and depression than the psychophysical presence of olfactory disorders. These findings emphasize the importance of considering patients’ perceptions to comprehensively assess the impact of olfactory disorders on their well-being.Trial registrationClinicalTrials.gov number (ID: NCT04799977).

One-year psychophysical evaluation of COVID-19-induced olfactory disorders: a prospective cohort study

BackgroundOlfactory disorders are common in COVID-19. While many patients recover within weeks, a notable number of patients suffer from prolonged olfactory disorders. Much research has focused on the acute phase of olfactory disorders in COVID-19; however, there is still inconsistency regarding the prognosis. We aim to assess both objective and subjective olfactory function in patients with persisting olfactory disorders following COVID-19, 1 year after diagnosis.MethodsWe objectively measured olfactory function in 77 patients who initially had COVID-19-induced smell disorders, 1 year after confirmed diagnosis. These patients previously underwent two objective measurements at approximately 3 and 6 months after COVID-19, in the context of the COCOS trial (COrticosteroids for COvid-19-induced loss of Smell). The main outcome measurement was TDI score (threshold-discrimination-identification) on Sniffin’ Sticks Test (SST). Secondary outcomes included objective gustatory function on Taste Strip Test (TST), self-reported olfactory, gustatory and trigeminal function on a visual analogue scale (VAS) and outcomes on questionnaires about quality of life, and nasal symptoms.ResultsThe findings of this study show that 1 year following COVID-19, the median TDI score increased to 30.75 (IQR 27.38–33.5), regarded as normosmia. The median TDI score started at 21.25 (IQR 18.25–24.75) at baseline and increased to 27.5 (IQR 23.63–30.0) at 6 months following COVID-19. The increase of 9.5 points on the TDI score between baseline and 1 year after COVID-19 marks a clinically relevant improvement. Regarding the self-reported VAS score (1–10) on sense of smell, it increased from 1.2 (IQR 0.4–3.0) at baseline to 3.2 (IQR 1.4–6.0) at 6 months and further improved up to 6.1 (IQR 2.7–7.5) after 1 year. Objective gustatory function increased with 2 points on TST a year after diagnosis. Self-reported olfactory, gustatory, and trigeminal functions also improved over time, as did quality of life.ConclusionsObjective and self-reported olfactory function continued to improve 1 year after COVID-19. The median TDI score of 30.75 (IQR 27.38–33.5) is regarded as normosmia, which is a favorable outcome. However, the rate of improvement on TDI score reduces over time.

Olfactory status in neurodegeneration with brain iron accumulation disorders.

Olfactory dysfunction has been suggested as a diagnostic and discriminative biomarker in some neurodegenerative disorders. However, there are few studies regarding the olfactory status in rare diseases including neurodegeneration with brain iron accumulation (NBIA) disorders. Genetically-confirmed NBIA patients were enrolled. Neurological and cognitive examinations were conducted according to the Pantothenate Kinase-Associated Neurodegeneration-Disease Rating Scale (PKAN-DRS) and the Mini-Mental State Examination (MMSE) questionnaire, respectively. Olfaction was assessed in three domains of odor threshold (OT), odor discrimination (OD), odor identification (OI), and total sum (TDI) score by the Sniffin' Sticks test. The olfactory scores were compared to a control group and a normative data set. Thirty-seven patients, including 22 PKAN, 6 Kufor Rakeb syndrome, 4 Mitochondrial membrane Protein-Associated Neurodegeneration (MPAN), 5 cases of other 4 subtypes, and 37 controls were enrolled. The mean PKAN-DRS score was 51.83±24.93. Sixteen patients (55.2%) had normal cognition based on MMSE. NBIA patients had significantly lower olfactory scores compared to the controls in TDI and all three subtests, and 60% of them were hyposmic according to the normative data. Including only the cognitively-normal patients, still, OI and TDI scores were significantly lower compared to the controls. The phospholipase A2-Associated Neurodegeneration (PLAN) and MPAN patients had a significantly lower OI score compared to the cognitively-matched PKAN patients. Olfactory impairment as a common finding in various subtypes of NBIA disorder can potentially be considered a discriminative biomarker. Better OI in PKAN compared to PLAN and MPAN patients may be related to the different underlying pathologies.

Intranasal insulin for COVID-19-related smell loss.

Quantitative (hyposmia and anosmia) and qualitative (phantosmia and parosmia) olfactory disorders are common consequences of COVID-19 infection found in more than 38% of patients even months after resolution of acute disease. SARS-CoV-2 has tropism for angiotensin-converting enzyme 2 (ACE2) in the respiratory system, suggesting that it is the mechanism of damage to the olfactory neuroepithelium and of involvement at the central nervous system. The olfactory bulb is the organ with the highest insulin uptake in the central nervous system. Insulin increases the production of Growth Factors (GF); therefore, in this study, the administration of intranasal insulin is proposed as a viable treatment for olfactory disturbances. The aim of this study was to obtain improvement in olfaction after 4 weeks of intranasal insulin administration in a group of patients presenting chronic olfactory disturbances secondary to COVID-19 infection, quantified using the Threshold, Discrimination, and Identification (TDI) score based on the Sniffin Sticks®. Experimental, longitudinal, prolective and prospective study of patients with a previous diagnosis of COVID-19 in the last 3-18months and who persisted with anosmia or hyposmia. The sample size was calculated with "satulator". The intervention was performed from January to May 2022. Throughout four appointments, a baseline olfactory measurement was obtained using the TDI score based on the Sniffin Sticks® test. In the first three appointments, Gelfoam® cottonoids soaked in 40IU of NPH insulin were placed on the nasal roof of each nostril for 15min. Descriptive statistics, student's paired t test and a multiple linear regression were utilized to ascertain statistical significance of the outcome on the TDI score obtained on the fourth and final appointment. 27 patients were included in the study. Table 1 summarizes the sample characteristics. The results exhibit that 93% of the sample had an improvement. The initial mean TDI score was 67% (63-71) compared to the final mean of 83% (80-86, p < 0.01). TDI subsection analysis is shown in Table 2. There was no significant difference in pre-intervention and post-intervention glucose measurements after the intranasal insulin administration. The administration of intranasal insulin has promising results, pointing towards an alternative of treatment for chronic olfactory disturbances secondary to neuroepithelial damage caused by upper respiratory tract infections. Furthermore, this is the first study to use a three-point assessment of olfaction in post-COVID-19 patients, while using the Sniffin Sticks® TDI score adapted to Latin Spanish.

The brain functional connectivity alterations in traumatic patients with olfactory disorder after low-level laser therapy demonstrated by fMRI.

Low-level laser therapy (LLLT) has been clinically accepted to accelerate the nerve regeneration process after a nerve injury or transection. We aimed to investigate the neuronal basis and the influence of LLLT on brain functional networks in traumatic patients with olfactory dysfunction. Twenty-four Patients with traumatic anosmia/hyposmia were exposed to pleasant olfactory stimuli during a block-designed fMRI session. After a 10-week period, patients as control group and patients who had completed the sessions of LLLT were invited for follow-up testing using the same fMRI protocol. Two-sample t-tests were conducted to explore group differences in activation responding to odorants (p-FDR-corrected <0.05). Differences of functional connectivity were compared between the two groups and the topological features of the olfactory network were calculated. Correlation analysis was performed between graph parameters and TDI score. Compared to controls, laser-treated patients showed increased activation in the cingulate, rectus gyrus, and some parts of the frontal gyrus. Shorter pathlength (p = 0.047) and increased local efficiency (p = 0.043) within the olfactory network, as well as decreased inter-network connectivity within the whole brain were observed in patients after laser surgery. Moreover, higher clustering and local efficiency were related to higher TDI score, as manifested in increased sensitivity to identify odors. The results support that low-level laser induces neural reorganization process and make new connections in the olfactory structures. Furthermore, the connectivity parameters may serve as potential biomarkers for traumatic anosmia or hyposmia by revealing the underlying neural mechanisms of LLLT.