International clinical assessment of smell: An international, cross-sectional survey of current practice in the assessment of olfaction.

OBJECTIVES: Olfactory dysfunction (OD) is common and carries significant personal and societal burden. Accurate assessment is necessary for good clinical and research practice but is highly dependent on the assessment technique used. Current practice with regards to UK/international clinical assessment is unknown. We aimed to capture current clinical practice, with reference to contemporaneously available guidelines. We further aimed to compare UK to international practice. DESIGN: Anonymous online questionnaire with cross-sectional non-probability sampling. Subgroup analysis according to subspeciality training in rhinology ('rhinologists' and 'non-rhinologists') was performed, with geographical comparisons only made according to subgroup. PARTICIPANTS: ENT surgeons who assess olfaction. RESULTS: Responses were received from 465 clinicians (217 from UK and 17 countries total). Country-specific response rate varied, with the lowest rate being obtained from Japan (1.4%) and highest from Greece (72.5%). Most UK clinicians do not perform psychophysical smell testing during any of the presented clinical scenarios-though rhinologists did so more often than non-rhinologists. The most frequent barriers to testing related to service provision (e.g., time/funding limitations). Whilst there was variability in practice, in general, international respondents performed psychophysical testing more frequently than those from the UK. Approximately 3/4 of all respondents said they would like to receive training in psychophysical smell testing. Patient reported outcome measures were infrequently used in the UK/internationally. More UK respondents performed diagnostic MRI scanning than international respondents. CONCLUSIONS: To our knowledge, this is the most comprehensive UK-based, and only international survey of clinical practice in the assessment of OD. We present recommendations to improve practice, including increased education and funding for psychophysical smell testing. We hope this will promote accurate and reliable olfactory assessment, as is the accepted standard in other sensory systems.

Axonal Regrowth of Olfactory Sensory Neurons In Vitro.

One of the most prevalent causes of olfactory loss includes traumatic brain injury with subsequent shearing of olfactory axons at the level of the cribriform plate (anterior skull base). Scar tissue at this level may prevent axonal regrowth toward the olfactory bulb. Currently, there is no cure for this debilitating and often permanent condition. One promising therapeutic concept is to implant a synthetic scaffold with growth factors through the cribriform plate/scar tissue to induce neuroregeneration. The first step toward this goal is to investigate the optimum conditions (growth factors, extracellular matrix proteins) to boost this regeneration. However, the lack of a specifically tailored in vitro model and an automated procedure for quantifying axonal length limits our ability to address this issue. The aim of this study is to create an automated quantification tool to measure axonal length and to determine the ideal growth factors and extracellular proteins to enhance axonal regrowth of olfactory sensory neurons in a mouse organotypic 2D model. We harvested olfactory epithelium (OE) of C57BL/6 mice and cultured them during 15 days on coverslips coated with various extracellular matrix proteins (Fibronectin, Collagen IV, Laminin, none) and different growth factors: fibroblast growth factor 2 (FGF2), brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), nerve growth factor (NGF), retinoic acid (RA), transforming growth factor ß (TGFß), and none. We measured the attachment rate on coverslips, the presence of cellular and axonal outgrowth, and finally, the total axonal length with a newly developed automated high-throughput quantification tool. Whereas the coatings did not influence attachment and neuronal outgrowth rates, the total axonal length was enhanced on fibronectin and collagen IV (p = 0.001). The optimum growth factor supplementation media to culture OE compared to the control condition were as follows: FGF2 alone and FGF2 from day 0 to 7 followed by FGF2 in combination with NGF from day 7 to 15 (p < 0.0001). The automated quantification tool to measure axonal length outperformed the standard Neuron J application by reducing the average analysis time from 22 to 3 min per specimen. In conclusion, robust regeneration of murine olfactory neurons in vitro can be induced, controlled, and efficiently measured using an automated quantification tool. These results will help advance the therapeutic concept closer toward preclinical studies.

[Parosmia and phantosmia: clinical update]. / Parosmie et fantosmie: mise à jour.

Olfactory disorders became known by large parts of the population since the Covid-19 pandemic. The causes of olfactory dysfunctions are manifold. Similar to other sensory impairments the disruption can be qualitative or quantitative. Quantitative olfactory disorders such as anosmia or hyposmia are well explored, whereas the knowledge on qualitative disorders such as parosmia or phantosmia is still limited. This article gives an update on the current clinical knowledge and workup of parosmia and phantosmia.

Depuis la pandémie de Covid-19, la population est davantage informée sur les troubles de l'odorat. Ils peuvent être d'origines multiples. Comme pour toute modalité sensorielle, il existe des atteintes quantitatives et qualitatives. Les troubles quantitatifs sont mieux connus et pris en charge mais les troubles qualitatifs restent méconnus. Cet article traite des troubles de l'odorat qualitatifs, notamment de la parosmie et de la fantosmie, ainsi que de leur prise en charge.

[Psychophysical olfactory testing : what's new ?] / Tests psychophysiques de l'olfaction : quoi de neuf ?

Olfactory disorders are common and may lead to severe consequences on quality of life. Medical management including treatment options can be proposed to the patients. For this reason, a correct diagnosis is important. Olfactory testing is one of the cornerstones for the diagnosis of smell impairment which helps to quantify the deficit. Despite good and widespread psychophysical olfactory tests, there are still many challenges in testing olfaction. Most of the current available test may not fully account for some cultural and genetic biases. Therefore it is difficult to develop olfactory tests and standardize them across different populations. In this paper we discuss an alternative method based on « white smells ¼ which may help to overcome these issues.

Les troubles olfactifs sont fréquents et peuvent parfois entraîner des conséquences importantes pour la qualité de vie des personnes concernées. Une prise en charge médicale et des traitements peuvent être proposés pour certains patients. Les tests olfactifs sont une des pierres angulaires dans le processus diagnostique qui permettent la quantification de la perte de l'odorat. Pour améliorer ces tests, des défis sont encore à relever. Leurs résultats peuvent parfois être biaisés par des facteurs culturels ou génétiques. L'une des possibles méthodes pour contourner ces problèmes est l'utilisation d'« odeurs blanches ¼, discutée dans cet article.

Mechanically evoked tinnitus after cochlear implantation with preservation of residual hearing.

In the recent past, inclusion criteria for cochlear implant surgery expanded to patients with ever more residual acoustic hearing in the low frequencies. By applying the meticulous hearing preservation surgical strategy and specifically designed atraumatic electrode arrays, residual hearing can be preserved to a meaningful extent in a large majority of patients. In this paper, we describe two female patients suffering from mechanically evoked tinnitus after hearing preservation cochlear implantation surgery with MEDEL flex electrodes. The occurrence of audible perceptions through mechanical stimulation in the region of the external ear is believed to be due to the direct transmission of movements via the electrode array to the basilar membrane of the inner ear. In both cases, the mechanically evoked tinnitus led to revision surgery with immobilization of the array in the mastoid cavity. Despite eliminating the tinnitus, the revision surgery led to a loss of residual hearing in one patient, whereas the relatively poor residual hearing in the other revision case remained unchanged. The presence of mechanically evoked tinnitus seems to be associated with increased fragility of inner ear structures and hearing function, possibly due to direct mechanical contact of the electrode array with the basilar membrane. Consequently, the electrode array needs to be carefully immobilized in the mastoid cavity at a distance from soft tissue to prevent mechanical damage of inner ear structures, particularly in female patients with fine muscular tissue.

How to Manage Taste Disorders.

Purpose of the Review: This study aims to summarize the current state of the art of how taste disorders are clinically best managed. Recent Findings: Taste disorders are distressing for the concerned patients since eating and drinking become bothersome or impossible. Apart from nutritional problems, quality of life is impaired. Still, diagnosis and treatment of taste disorders are elusive, and general knowledge about taste and its affection is little within the population and the medical community. This review stresses the importance of accurate workup and diagnosis of taste disorders in order to offer an effective treatment. Yet unclear aspects of taste disorders are discussed, and interesting findings regarding the treatment of taste disorders are reviewed. A special focus is given to current pharmacological options on how to treat taste disorders. Summary: Despite impressive insights into the gustatory function and molecular logic of taste receptor cells, there is currently poor clinical knowledge on the pathophysiology of taste disorders in humans. Diagnosing, measuring, and treating gustatory disorders remain restricted to a handful of specialized smell and taste centers worldwide. Despite interesting work on potential drugs treating taste disorders, many of the reported medications lack controlled and randomized trials confirming their efficacy in taste dysfunction. Future efforts need to be focused on the treatment of taste disorders.

Chemosensory decrease in different forms of olfactory dysfunction.

The aim of this study is to investigate the effect of olfactory dysfunction (OD) on the two other chemical senses, namely gustation and the intranasal trigeminal system. Taste and trigeminal function were analyzed in a retrospective cross-sectional study of 178 participants with OD (n = 78 posttraumatic, n = 42 idiopathic, n = 27 post-infectious and n = 31 chronic rhinosinusitis (CRS) OD). All patients had been investigated for OD at our smell and taste outpatient clinic. Evaluation of olfaction was performed by means of the Sniffin' Sticks test (odor threshold, odor discrimination and odor identification), whereas gustatory function was assessed with the Taste Strips test and the intranasal trigeminal sensitivity by means of the lateralization task. The degree of olfactory impairment was found to depend on the cause of OD, but not on patients' age. Patients with posttraumatic OD showed lower olfactory function than patients with idiopathic, post-infectious and CRS OD (p = 0.01). Gustatory and trigeminal sensitivity in turn depended on age rather than the cause of olfactory dysfunction. Partial correlations between olfactory, gustatory, and trigeminal scores, with age as covariate, were significant, showing a decrease of taste and trigeminal function proportional to the OD (p < 0.05). The present data suggest that the three chemical senses are closely connected for humans underlining that in case of OD the remaining chemical senses (taste, trigeminal function) tend to decrease rather than compensate as this is seen for sensory loss in other modalities. This finding has direct clinical implications and importance when dealing with smell and taste disorders.

Olfactory dysfunction in frontotemporal dementia and psychiatric disorders: A systematic review.

Frontotemporal dementia (FTD) is a progressive neurodegenerative disease. Diagnosis of FTD, especially the behavioural variant, is challenging because of symptomatic overlap with psychiatric disorders (depression, schizophrenia, bipolar disorder). Olfactory dysfunction is common in both FTD and psychiatric disorders, and often appears years before symptom onset. This systematic review analysed 74 studies on olfactory function in FTD, depression, schizophrenia and bipolar disorder to identify differences in olfactory dysfunction profiles, focusing on the most common smell measures: odour identification and discrimination. Results revealed that FTD patients were severely impaired in odour identification but not discrimination; in contrast, patients diagnosed with schizophrenia showed impairments in both measures, while those diagnosed with depression showed no olfactory impairments. Findings in bipolar disorder were mixed. Therefore, testing odour identification and discrimination differentiates FTD from depression and schizophrenia, but not from bipolar disorder. Given the high prevalence of odour identification impairments in FTD, and that smell dysfunction predicts neurodegeneration in other diseases, olfactory testing seems a promising avenue towards improving diagnosis between FTD and psychiatric disorders.