Position paper on olfactory dysfunction: 2023

BACKGROUND: Since publication of the original Position Paper on Olfactory Dysfunction in 2017 (PPOD-17), the personal and societal burden of olfactory disorders has come sharply into focus through the lens of the COVID-19 pandemic. Clinicians, scientists and the public are now more aware of the importance of olfaction, and the impact of its dysfunction on quality of life, nutrition, social relationships and mental health. Accordingly, new basic, translational and clinical research has resulted in significant progress since the PPOD-17. In this updated document, we present and discuss currently available evidence for the diagnosis and management of olfactory dysfunction. Major updates to the current version include, amongst others: new recommendations on olfactory related terminology; new imaging recommendations; new sections on qualitative OD and COVID-19 OD; updated management section. Recommendations were agreed by all co-authors using a modified Delphi process. CONCLUSIONS: We have provided an overview of current evidence and expert-agreed recommendations for the definition, investigation, and management of OD. As for our original Position Paper, we hope that this updated document will encourage clinicians and researchers to adopt a common language, and in so doing, increase the methodological quality, consistency, and generalisability of work in this field.

Hedonic perception of odors in children aged 5-8 years is similar across 18 countries: Preliminary data.

OBJECTIVE: Olfactory preference emerges very early in life, and the sense of smell in children rapidly develops until the second decade of life. It is still unclear whether hedonic perception of odors is shared in children inhabiting different regions of the globe. METHODS: Five-hundred ten healthy children (N = 510; ngirls = 256; nboys = 254) aged from 5 to 8 years from 18 countries rated the pleasantness of 17 odors. RESULTS: The hedonic perception of odors in children aged between 5 and 8 years was rather consistent across 18 countries and mainly driven by the qualities of an odor and the overall ability of children to label odorants. CONCLUSION: Conclusions from this study, being a secondary analysis, are limited to the presented set of odors that were initially selected for the development of U-Sniff test and present null findings for the cross-cultural variability in hedonic perception of odors across 18 countries. These two major issues should be addressed in the future to either contradict or replicate the results presented herewith. This research lays fundament for posing further research questions about the developmental aspects of hedonic perception of odors and opens a new door for investigating cross-cultural differences in chemosensory perception of children.

Factors associated with relevant olfactory recovery after olfactory training: a retrospective study including 601 participants.

BACKGROUND: Olfactory training (OT) represents a therapeutic option for multiple etiologies of olfactory dysfunction (OD) that also benefits normosmic subjects. In this retrospective study, we report the effectiveness of OT and factors associated with relevant changes in olfactory function (OF) in large groups of normosmic participants and patients with OD, including a control group that performed no training. METHODS: This was a retrospective pooled analysis including 2 treatment cohorts of 8 previously published studies. Adult partici- pants that either presented with the major complaint of quantitative OD or normosmic volunteers were recruited at various ENT clinics and received OT or no training. The outcome was based on changes in objective olfactory test scores after OT. RESULTS: A total of 601 patients with OD or normosmic subjects were included. OT was more effective compared to no training. No interaction was found between OT and OF. In multivariate analysis, higher baseline OF (adjusted odds ratio, aOR, 0.93) and posttraumatic (aOR, 0.29) or idiopathic OD (aOR, 0.18) compared to postinfectious causes were significantly associated with lower odds of relevant improvements in patients with OD receiving OT. Subgroup analysis of normosmic participants receiving OT further revealed a significant association of age and baseline olfactory function with improvements of overall OF. CONCLUSIONS: This study demonstrated that OT was more effective than no training in patients with various causes of OD. Additi- onally, baseline olfactory performance and etiology of OD were identified as important factors associated with relevant improve- ments after OT.

Comparison of COVID-19 and common cold chemosensory dysfunction.

Anosmia constitutes a prominent symptom of COVID-19. However, anosmia is also a common symptom of acute colds of various origins. In contrast to an acute cold, it appears from several questionnaire-based studies that in the context of COVID-19 infection, anosmia is the main rhinological symptom and is usually not associated with other rhinological symptoms such as rhinorrhoea or nasal obstruction. Until now, no study has directly compared smell and taste function between COVID-19 patients and patients with other causes of upper respiratory tract infection (URTI) using valid and reliable psychophysical tests. In this study, we aimed to objectively assess and compare olfactory and gustatory functions in 10 COVID-19 patients (PCR diagnosed, assessed on average 2 weeks after infection), 10 acute cold (AC) patients (assessed before the COVID-19 outbreak) and 10 healthy controls, matched for age and sex. Smell performance was assessed using the extended "Sniffin' Sticks" test battery (4), while taste function was assessed using "taste strips" (5). Receiver Operating Characteristic (ROC) curves were built to probe olfactory and gustatory scores in terms of their discrimination between COVID-19 and AC patients. Our results suggest that mechanisms of COVID-19 related olfactory dysfunction are different from those seen in an AC and may reflect, at least to some extent, a specific involvement at the level of central nervous system in some COVID-19 patients. In the future, studies to assess the prevalence of persistent anosmia and neuroanatomical changes on MRI correlated to chemosensory function, will be useful to understand these mechanisms.

Position paper on olfactory dysfunction.

Background: Olfactory dysfunction is an increasingly recognised condition, associated with reduced quality of life and major health outcomes such as neurodegeneration and death. However, translational research in this field is limited by heterogeneity in methodological approach, including definitions of impairment, improvement and appropriate assessment techniques. Accordingly, effective treatments for smell loss are limited. In an effort to encourage high quality and comparable work in this field, among others, we propose the following ideas and recommendations. Whilst the full set of recommendations are outlined in the main document, points include the following: • Patients with suspected olfactory loss should undergo a full examination of the head and neck, including rigid nasal endoscopy with small diameter endoscopes. • Subjective olfactory assessment should not be undertaken in isolation, given its poor reliability. • Psychophysical assessment tools used in clinical and research settings should include reliable and validated tests of odour threshold, and/or one of odour identification or discrimination. • Comprehensive chemosensory assessment should include gustatory screening. • Smell training can be helpful in patients with olfactory loss of several aetiologies. Conclusions: We hope the current manuscript will encourage clinicians and researchers to adopt a common language, and in so doing, increase the methodological quality, consistency and generalisability of work in this field.

Thyroid Hormone Replacement Therapy Improves Olfaction and Taste Sensitivity in Primary Hypothyroid Patients: A Prospective Randomised Clinical Trial.

Smell and taste are known to be influenced by thyroid function changes. However, many hypothyroid patients and physicians are unaware of their dysosmia and dysgeusia. The present study was performed to shed more light on the relation between hypothyroidism and olfactory loss. 32 primary hypothyroid patients and 31 controls enrolled in the prospective randomized interventional study. Newly diagnosed Primary hypothyroid patients were treated with L-thyroxine for 3-6 months. The control group was selected on the basis of the biochemical evidence of a normal thyroid function. Psychophysiological olfactory testing was performed using odor dispensers similar to felt-tip pens ("Sniffin' Sticks", Burghart, Wedel, Germany). Taste function tests were made using "Taste Strips" (Burghart, Wedel, Germany) which are basically tastant adsorbed filter paper strip. Smell identification, threshold, discrimination, TDI scores, bitter and sweet taste scores were significantly lower in untreated hypothyroid patients compared to controls (12.31±1.09 vs. 14.03±1.05, p<0.001; 7.09±1.15 vs. 8.89±1.12, p<0.001; 11.47±0.95 vs. 13.06±0.85, p<0.001; 30.90±2.70 vs. 35.89±2.07, p<0.001; 4.88±1.6 vs. 6.64±0.96, p<0.001; and 5.5±2.22 vs. 6.58±1.28, p=0.021) respectively. Comparison of scores at the third month of treatment and before treatment of hypothyroid patients revealed significant improvement in smell and taste functions in terms of identification, threshold, discrimination, TDI scores, bitter, sweet and salty tastes (12.31±1.09 vs. 13.84±1.22, p<0.001; 7.09±1.15 vs. 8.02±1.16, p<0.001; 11.47±0.95 vs. 12.41±1.21, p<0.001; 30.90±2.70 vs. 34.27±3.25, p<0.001; 4.88±1.6 vs. 6.06±1.4, p<0.001; 5.5±2.22 vs. 6.38±1.28, p<0.001; and 6.12±2.32 vs. 6.62±1.48, p=0.044) respectively. On correlation analysis, there was a negative correlation between TPO-Ab levels and discrimination, identification and TDI scores (r=-0.409, p=0.02; r=-0.424, p=0.016; r=-0.532, p=0.002), and also between Tg-Ab levels and identification, TDI, and bitter scores (r=-0.423, p=0.016; r=-0.468, p=0.007; r=-0.409, p=0.02) respectively. Primary hypothyroidism was found to have a negative effect on smell and taste. RAI treatment was found to be most destructive on smell and taste compared to surgical and autoimmune hypothyroidism. Treatment of hypothyroidism was positively correlated with an improvement of both senses. Thus, the future workup of patients with smell/taste loss should include investigations for thyroid functions.

Evaluation of halitosis using OralChroma™ in patients with allergic rhinitis.

OBJECTIVE: The objective of this study was to evaluate the occurrence of halitosis in patients with allergic rhinitis (AR). MATERIALS AND METHODS: In this study, we enrolled 53 patients with AR and 34 participants as controls. Halitosis was evaluated by measuring volatile sulphur compound (VSC) levels. VSCs, which consist of hydrogen sulphide (HS), methyl mercaptan (MM), and dimethyl sulphide (DMS), were measured using a portable gas chromatograph (OralChroma™; AbiMedical, Osaka, Japan). RESULTS: Patients with AR exhibited significantly higher levels of MM and DMS that did control subjects. Specifically, MM levels showed a greater increase than DMS levels in patients with AR than in controls. We observed no significant changes in the levels of HS between the groups. CONCLUSION: This study demonstrated that AR is likely to result in halitosis. Several studies have overlooked the relationship between halitosis and AR. In light of our results, we suggest that halitosis should be further investigated in patients with AR.

Position paper on olfactory dysfunction.

BACKGROUND: Olfactory dysfunction is an increasingly recognised condition, associated with reduced quality of life and major health outcomes such as neurodegeneration and death. However, translational research in this field is limited by heterogeneity in methodological approach, including definitions of impairment, improvement and appropriate assessment techniques. Accordingly, effective treatments for smell loss are limited. In an effort to encourage high quality and comparable work in this field, among others, we propose the following ideas and recommendations. Whilst the full set of recommendations are outlined in the main document, points include the following: - Patients with suspected olfactory loss should undergo a full examination of the head and neck, including rigid nasal endoscopy with small diameter endoscopes. - Subjective olfactory assessment should not be undertaken in isolation, given its poor reliability. - Psychophysical assessment tools used in clinical and research settings should include reliable and validated tests of odour threshold, and/or one of odour identification or discrimination. - Comprehensive chemosensory assessment should include gustatory screening. - Smell training can be helpful in patients with olfactory loss of several aetiologies. CONCLUSIONS: We hope the current manuscript will encourage clinicians and researchers to adopt a common language, and in so doing, increase the methodological quality, consistency and generalisability of work in this field.

Examination versus subjective nasal obstruction in the evaluation of the nasal septal deviation.

BACKGROUND: Nasal septal deviation (NSD) is a frequent complaint among patients in an otolaryngology clinic. The prevalence of NSD varies in different populations and NSD classification schemes are complex. METHODS: We aimed to determine the prevalence of NSD in a population of Turkish young males using a new NSD classification method that we developed. We compared the results with patients' complaints. All patients underwent two nasal examinations, which were performed using a nasal speculum with and without administration of vasoconstrictor agents. Inferior Concha Hypertrophy (ICH) was evaluated in the first examination and NSDs were scored during the second examination. All findings were recorded according to our classification scheme. Severity of nasal obstruction was subjectively evaluated by using a visual analogue scale (VAS). RESULTS: We found a significant association between prevalence of NSD and nasal injuries, but there was no association between the mode of delivery and prevalence of NSD. Surprisingly, about 30 % of the participants with NSD had no complaint of nasal obstruction. Although most of the participants in the study had no severe nasal obstruction complaint, we found an association between NSD presence and patient's VAS. CONCLUSION: NSD is very frequent in the Turkish population and most often related to trauma; however, its effect on patient quality of life varies.