Olfactory Nomenclature: An Orchestrated Effort to Clarify Terms and Definitions of Dysosmia, Anosmia, Hyposmia, Normosmia, Hyperosmia, Olfactory Intolerance, Parosmia, and Phantosmia/Olfactory Hallucination.

BACKGROUND: Definitions are essential for effective communication and discourse, particularly in science. They allow the shared understanding of a thought or idea, generalization of knowledge, and comparison across scientific investigation. The current terms describing olfactory dysfunction are vague and overlapping. SUMMARY: As a group of clinical olfactory researchers, we propose the standardization of the terms "dysosmia," "anosmia," "hyposmia," "normosmia," "hyperosmia," "olfactory intolerance," "parosmia," and "phantosmia" (or "olfactory hallucination") in olfaction-related communication, with specific definitions in this text. KEY MESSAGES: The words included in this paper were determined as those which are most frequently used in the context of olfactory function and dysfunction, in both clinical and research settings. Despite widespread use in publications, however, there still exists some disagreement in the literature regarding the definitions of terms related to olfaction. Multiple overlapping and imprecise terms that are currently in use are confusing and hinder clarity and universal understanding of these concepts. There is a pressing need to have a unified agreement on the definitions of these olfactory terms by researchers working in the field of chemosensory sciences. With the increased interest in olfaction, precise use of these terms will improve the ability to integrate and advance knowledge in this field.

Nostril Differences in the Olfactory Performance in Health and Disease.

In the past few decades, several olfactory tests have been developed to assess olfactory performance and detect disorders. Contrary to other sensory systems, both nostrils are usually tested together; we hypothesized that monorhinal testing may reveal side differences in sensitivity which may be useful for the diagnosis of olfactory dysfunction. Using the "Sniffin' Sticks" test, we assessed olfactory function of 458 participants (278 healthy controls, 180 hyposmic patients), one nostril after the other, with 3 different tasks. For each participant and each task, we compared the scores obtained with both nostrils, and defined the best and worst nostrils. Thus we were able to establish normative data and to define cut-off values. Our results suggest that scores obtained with the worst nostril are the most efficient in detecting an olfactory disorder. This supports the importance of monorhinal testing, as it can allow an earlier and more accurate diagnosis than birhinal testing. This may be especially useful in the context of early detection of neurodegenerative diseases.

Anosmia-A Clinical Review.

Anosmia and hyposmia, the inability or decreased ability to smell, is estimated to afflict 3-20% of the population. Risk of olfactory dysfunction increases with old age and may also result from chronic sinonasal diseases, severe head trauma, and upper respiratory infections, or neurodegenerative diseases. These disorders impair the ability to sense warning odors in foods and the environment, as well as hinder the quality of life related to social interactions, eating, and feelings of well-being. This article reports and extends on a clinical update commencing at the 2016 Association for Chemoreception Sciences annual meeting. Included were reports from: a patient perspective on losing the sense of smell with information on Fifth Sense, a nonprofit advocacy organization for patients with olfactory disorders; an otolaryngologist's review of clinical evaluation, diagnosis, and management/treatment of anosmia; and researchers' review of recent advances in potential anosmia treatments from fundamental science, in animal, cellular, or genetic models. As limited evidence-based treatments exist for anosmia, dissemination of information on anosmia-related health risks is needed. This could include feasible and useful screening measures for olfactory dysfunction, appropriate clinical evaluation, and patient counseling to avoid harm as well as manage health and quality of life with anosmia.

Short-term effect of caffeine on olfactory function in hyposmic patients.

The purpose of this study was to investigate the potential effects of caffeine in patients with olfactory loss. The suggested mechanisms of action consist in the non-selective blocking of adenosine receptors as well as inhibition of the phospodiesterase. Olfactory function was tested twice in 76 hyposmic patients either because of URTI or because of sinunasal causes. For definition of hyposmia and for later assessment of phenyl ethyl alcohol odor threshold, and odor discrimination the Sniffin Sticks data test was used. Using a double-blinded design, the participants were divided into two groups: one received a cup of espresso with caffeine (65 mg/cup), the other a cup of espresso without caffeine (placebo). Before and approximately 45 min after espresso consumption olfactory function was assessed. Across all participants, in comparison to placebo there was no significant effect of caffeine on olfactory function, regardless whether it was caused by an acute infection of the upper respiratory tract or sinunasal disease. These results indicate that-under the current conditions-the phosphodiesterase-inhibitor/adenosine-receptor agonist caffeine has little or no short-term effect on olfactory function in patients with olfactory loss.

Retronasal testing of olfactory function: an investigation and comparison in seven countries.

Flavor perception is to a large extent determined by olfaction, and persons who lost their sense of smell consequently complain about strongly reduced enjoyment of food. The retronasal olfactory function is especially important for flavor appreciation. The aim of this study was to compare retronasal function across different cultures and to develop a test that is applicable across cultures. Identification of 39 retronasal applied odor probes was tested in a total of 518 participants of seven countries; 292 of them were healthy, and 226 exhibited a smell disorder. A retest was performed with 224 of the healthy participants. Furthermore, all participants were tested for orthonasal threshold, identification, and discrimination ability. Significant cultural differences in identification ability were found in 92% of the probes. The 20 probes that could be identified above chance in healthy participants of all countries and that could differentiate between patients and controls were selected for the final retronasal test. This test was well able to differentiate between controls and patients in different countries and showed a good coherence with the orthonasal test (r = 0.80) and a good retest-reliability (r = 0.76). Furthermore, it is age-independent. The strong cultural differences observed in retronasal identification underline the necessity to develop a culturally independent instrument. This retronasal test is easy to apply and can be used across different countries for diagnostics and clinical research.

SARS-CoV-2 Leads to Significantly More Severe Olfactory Loss than Other Seasonal Cold Viruses.

The aim of this study was to investigate whether COVID-associated olfactory impairment differs from olfactory disorders due to other upper respiratory tract infections. We investigated the frequency of a SARS-CoV-2 infection among subjects presenting with a subjective olfactory impairment to a corona outpatient clinic between October 2020 and March 2021. Olfactory and gustatory loss were tested psychophysically, and the type of infection, SARS-CoV-2 versus 14 other common cold viruses, was assessed with nasopharyngeal swabs. Differences between the smell impairment caused by the pathogens were compared. Out of the 2120 patients, 314 reported sudden smell and/or taste loss (14%). In 68.9% of them, olfactory and in 25.6%, gustatory dysfunction could be confirmed by psychophysical testing. Of those with a psychophysically determined loss of smell, 61% were tested positive for SARS-CoV-2. SARS-CoV-2 led to a significantly more severe loss of smell and more qualitative olfactory disorders than other pathogens. Apart from rhinorrhea, shortness of breath and sore throat accompanying cold symptoms do not differ significantly between the viruses indicating the particular importance of smell loss in the differential diagnosis of seasonal colds. Multiplex-PCR in non-COVID patients revealed that only 27% of them had rhinoviruses, whereas the remainder were no further identified pathogens. Olfactory screening significantly increases diagnostic accuracy in COVID-19 patients compared to subjective assessment of olfactory loss.

Systemic corticosteroids in coronavirus disease 2019 (COVID-19)-related smell dysfunction: an international view.

The frequent association between coronavirus disease 2019 (COVID-19) and olfactory dysfunction is creating an unprecedented demand for a treatment of the olfactory loss. Systemic corticosteroids have been considered as a therapeutic option. However, based on current literature, we call for caution using these treatments in early COVID-19-related olfactory dysfunction because: (1) evidence supporting their usefulness is weak; (2) the rate of spontaneous recovery of COVID-19-related olfactory dysfunction is high; and (3) corticosteroids have well-known potential adverse effects. We encourage randomized placebo-controlled trials investigating the efficacy of systemic steroids in this indication and strongly emphasize to initially consider smell training, which is supported by a robust evidence base and has no known side effects.

The impact of postoperative nasal packing on sleep-disordered breathing and nocturnal oxygen saturation in patients with obstructive sleep apnea syndrome.

Nasal septum surgery is frequently performed to establish a functional nasal airway. In these patients obstructive sleep apnea syndrome (OSAS) is frequently present. Although patients with OSAS are at increased risk for hypoxemia, the impact of postoperative nasal packing (PNP) on sleep-disordered breathing and oxygen desaturations in patients with OSAS is unknown. We consecutively investigated 40 patients undergoing endonasal surgery receiving PNP. Fifteen of these patients had previously diagnosed OSAS (Group 2) and 25 did not (Group 1). In the control group, 12 healthy patients underwent elective ear or neck surgery without PNP. During the preoperative and postoperative nights, we continuously measured oronasal flow, thoracoabdominal movements, and oxygen saturation. We calculated the apnea-hypopnea index (AHI) and the oxygen-desaturation index (ODI). Compared with the preoperative values, after the operation, neither AHI nor ODI changed in the control group. In contrast, in Group 1, AHI (from 11 [5-19] to 37 [22-49]) and ODI (from 4 [2-8] to 13 [6-21]) significantly increased (P < 0.05), whereas in Group 2, only AHI significantly increased (from 14 [10-21] to 39 [26-50]); ODI remained similar (13 [8-27] versus 11 [4-37]). Because ODI did not increase in patients with OSAS and PNP who received postoperative oxygen overnight, postoperative intensive care monitoring might not be necessary on a routine basis for all patients with PNP and OSAS.

Endonasal surgery for contact point headaches: a 10-year longitudinal study.

OBJECTIVE: Some migraine and cluster headaches may be triggered by stimulation of intranasal contact points via the trigeminovascular system. Endonasal surgery is successful in some patients, but long-term outcomes have not been reported. STUDY DESIGN: Prospective. METHODS: This investigation included 20 patients with a mean 18-year history of refractory cluster or migraine headaches who were selected for surgery. All had endoscopically visible endonasal contact as well as a positive preoperative cocaine test result. Changes in pain severity and frequency and duration of headache attacks were statistically rated using a MANOVA. Follow-up averaged 112 months. RESULTS: Almost 10 years after surgery, six patients remained completely free of pain, seven had significant symptom improvement, and seven received no benefit from surgery (65% improvement). Two patients had been free of all symptoms for 7 and 8 years, respectively, before complaints returned. CONCLUSION: Our data suggest that some patients with refractory headaches and endonasal contact areas benefit from surgery, thereby supporting the existence of a connection between the two. Even though it is clear that surgery should be considered only if all other treatments have failed, a success rate of 65% over almost 10 years justifies evaluation of this option. Preoperative patient selection remains crucial and warrants further investigation.

Reversible anosmia after amikacin therapy.

Olfactory disorders are among the rare adverse effects of antibiotic therapy. To date, olfactory losses or distortions have been reported after the use of doxycycline, amoxicillin, clarithromycin, roxithromycin, kanamycin sulfate, and streptomycin sulfate. We describe what we believe to be the first case of transient anosmia associated with the use of intravenous amikacin sulfate. The appearance of the disorder and its subsequent resolution were demonstrated by psychometric testing as well as by chemosensory evoked potentials. Based on the well-documented temporal course of the anosmia, there is a probable causal correlation between the administration of amikacin and the appearance of the olfactory disturbance. However, the exact pathogenesis of the anosmia is still a matter of conjecture.

[Testing the sense of smell using validated procedures]. / Die Prüfung des Riechvermögens mit validierten Verfahren.

There is a growing interest into the investigation of smell disorders in both research and clinical practice. For psychophysical ("subjective") investigations related to the sense of smell a variety of test kits are available, namely the various "Sniffin' Sticks" kits, the UPSIT (University of Pennsylvania Smell Identification Test) or the CCSIT (Cross-Cultural Smell Identification Test). Recording of olfactory evoked potentials (OEPs) and respiration olfactometry can be used for diagnosing smell dysfunctions in a more objective way.

[Testing the sense of taste using validated procedures]. / Die Prüfung des Schmeckvermögens mit validierten Verfahren.

Psychophysical tests related to the sense of taste are usually less complex than those of the sense of smell. In addition to global tests a regional examination of the sense of taste might be indicated to search for nerve lesions. There are numerous validated psychophysical tests available based on the administration of liquid or solid substrates. The use of electrical currents (electrogustometry) is especially feasible for a rapid regional testing. The registration of gustatory event-related potentials to objectify results from psychophysical examination is possible although limited to a few centers world-wide.

European position paper on the anatomical terminology of the internal nose and paranasal sinuses.

The advent of endoscopic sinus surgery led to a resurgence of interest in the detailed anatomy of the internal nose and paranasal sinuses. However, the official Terminologica Anatomica used by basic anatomists omits many of the structures of surgical importance. This led to numerous clinical anatomy papers and much discussion about the exact names and definitions for the structures of surgical relevance. This European Position Paper on the Anatomical Terminology of the Internal Nose and Paranasal Sinuses was conceived to re-evaluate the anatomical terms in common usage by endoscopic sinus surgeons and to compare this with the official Terminologica Anatomica. The text is a concise summary of all the structures encountered during routine endoscopic surgery in the nasal cavity, paranasal sinuses and at the interface with the orbit and skull base but does not provide a comprehensive text for advanced skull base surgery. It draws on a detailed review of the literature and provides a consensus where several options are available, defining the anatomical structure in simple terms and in English. It is recognised that this is an area of great variation and some indication of the frequency with which these variants are encountered is given in the text and table. All major anatomical points are illustrated, drawing on the expertise of the multi-national and multi-disciplinary contributors to this project.

Psychophysical effects of nasal and oral inflammation.

Olfactory disorders are common in "nasal inflammation" even though the term is comprehensive and subsumes different kinds of entities which have to be differentiated. The most common cause of olfactory disorders are sinonasal disorders, which are defined as secondary smell disorders caused by diseases/pathologies in the nose/paranasal sinuses. According to the literature, sinonasal disorders represent--depending on the examined population-up to 72% of all olfactory disorders. In general, noninflammatory and inflammatory disorders are differentiated. Inflammatory disorders can be further classified into infectious or noninfectious disorders, both forms in which olfactory disorders can be present. For the clinician examining patients, the exact classification of the olfactory disorder is mandatory in order to choose appropriate treatment and counseling. Among the most common inflammatory disorders are acute rhinitis, allergic rhinitis, post-upper respiratory tract infection and chronic rhinosinusitis, which are discussed in detail. In contrast to nasal inflammation, only little is known about oral inflammation and its psychophysical effects on taste function. Taste disorders following oral inflammation are briefly discussed.

"Taste Strips" - a rapid, lateralized, gustatory bedside identification test based on impregnated filter papers.

OBJECTIVE: To elaborate normative values for a clinical psychophysical taste test ("Taste Strips"). BACKGROUND: The "Taste Strips" are a psychophysical chemical taste test. So far, no definitive normative data had been published and only a fairly small sample size has been investigated. In light of this shortcoming for this easy, reliable and quick taste testing device, we attempted to provide normative values suitable for the clinical use. SETTING: Normative value acquisition study, multicenter study. METHODS: The investigation involved 537 participants reporting a normal sense of smell and taste (318 female, 219 male, mean age 44 years, age range 18-87 years). The taste test was based on spoon-shaped filter paper strips ("Taste Strips") impregnated with the four (sweet, sour, salty, and bitter) taste qualities in four different concentrations. The strips were placed on the left or right side of the anterior third of the extended tongue, resulting in a total of 32 trials. With their tongue still extended, patients had to identify the taste from a list of four descriptors, i. e., sweet, sour, salty, and bitter (multiple forced-choice). To obtain an impression of overall gustatory function, the number of correctly identified tastes was summed up for a "taste score". RESULTS: Taste function decreased significantly with age. Women exhibited significantly higher taste scores than men which was true for all age groups. The taste score at the 10(th) percentile was selected as a cut-off value to distinguish normogeusia from hypogeusia. Results from a small series of patients with ageusia confirmed the clinical usefulness of the proposed normative values. CONCLUSION: The present data provide normative values for the "Taste Strips" based on over 500 subjects tested.

What is the correlation between ratings and measures of olfactory function in patients with olfactory loss?

BACKGROUND: Major complaints of many patients with olfactory dysfunction relate to the impairment of quality of life. Nevertheless, it is unclear to what extent there is a correlation between ratings of olfactory abilities/impairment and olfactory function. METHODS: Patients with olfactory dysfunction (n = 152) were examined psychometrically using the "Sniffin' Sticks" test battery. Ratings of olfactory function and ratings of impairment were recorded using visual analog scales. RESULTS: Following standardized olfactory testing, 78 of the 152 patients were categorized as functionally anosmic, 64 as hyposmic, and 10 as normosmic. Groups differed significantly with regard to ratings of olfactory function. Functionally anosmic patients rated impairment to be significantly higher compared with hyposmic and normosmic patients. Ratings of olfactory function correlated significantly with measured olfactory function (r = +0.57) and ratings of impairment (r = -0.30). CONCLUSION: There was a moderate correlation between ratings and measures of olfactory function. On average, functionally anosmic patients recognized their olfactory loss, although, on an individual basis, there were striking differences between measures and ratings of olfactory function.