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.

[Cough from an allergological as well as from the ENT aspect]

Cough from an allergological as well as from the ENT aspect Abstract. Cough is a common problem in the allergological, but less so in the rhinological consultation. The differential diagnostic spectrum for cough is extensive and may range from rhinitis and asthma to eosinophilic esophagitis and rarer diseases. In the case of chronic cough (> 2 months), the four most frequent causes must be sought, or be excluded (upper airway cough syndrome, asthma [cough-variant-asthma], non-asthmatic eosinophilic bronchitis, gastroesophageal reflux disease). Aeroallergens such as pollen, house-dust mites or occupational substances play a major role in allergies. Nevertheless, it is not uncommon for cough to be a main symptom of an antibody deficiency or a Sicca symptom complex. The more chronic the cough, the more thoroughly an investigation is indicated - often interdisciplinary. Therapy depends on the cause of the cough. In allergic respiratory diseases, allergy-specific immunotherapy may be indicated.

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.

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

OBJECTIVE

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 participants 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 lower 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. Additionally, baseline olfactory performance and etiology of OD were identified as important factors associated with relevant improvements after OT.

Trigeminal endonasal perception - an outcome predictor for septoplasty

BACKGROUND

No adequate test exists to predict outcome after septoplasty. Despite adequate surgery, patients still might experience nasal breathing impairment. The aim of this study was to determine if pre-operative trigeminal sensitivity can predict satisfaction after septoplasty.

METHODS

Single centre prospective cohort study in tertiary referral centre with follow-up time of 6 weeks postoperatively. Patients scheduled for septoplasty or septorhinoplasty with turbinoplasty were consecutively selected the day before surgery. Standard preoperative examinations (acoustic rhinometry and Sniffin’ Sticks 12 test), the evaluation of nasal obstruction on a visual analogue scale (VAS) and the trigeminal lateralisation task were performed before and 6 weeks after surgery. Biopsies were taken during surgery and TRPV1 mRNA expression was measured by PCR.

RESULTS

Thirty patients were included with a median age of 29 years and equal gender distribution. Trigeminal perception and sensation of nasal obstruction showed a significant correlation: preoperative lateralisation test scores, representing endonasal trigeminal sensitivity, correlated significantly with the mean VAS change scores, which demonstrate subjective improvement. A lateralisation test score of 31.5 and more had a sensitivity of 88% to predict an improvement of more than 3 VAS points. Additionally, high TRPV1 mRNA expression was linked with good postoperative VAS scores.

CONCLUSION

The preoperative evaluation of the trigeminal sensitivity could improve patients’ selection for septoplasty with a higher rate of satisfaction. Endonasal trigeminal sensitivity is directly linked with subjective outcome. Therefore, patients with low trigeminal sensitivity should undergo septoplasty only after thorough counselling.

Clinical Olfactory Working Group consensus statement on the treatment of postinfectious olfactory dysfunction

BACKGROUND

Respiratory tract viruses are the second most common cause of olfactory dysfunction. As we learn more about the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with the recognition that olfactory dysfunction is a key symptom of this disease process, there is a greater need than ever for evidence-based management of postinfectious olfactory dysfunction (PIOD).

OBJECTIVE

Our aim was to provide an evidence-based practical guide to the management of PIOD (including post-coronavirus 2019 cases) for both primary care practitioners and hospital specialists.

METHODS

A systematic review of the treatment options available for the management of PIOD was performed. The written systematic review was then circulated among the members of the Clinical Olfactory Working Group for their perusal before roundtable expert discussion of the treatment options. The group also undertook a survey to determine their current clinical practice with regard to treatment of PIOD.

RESULTS

The search resulted in 467 citations, of which 107 articles were fully reviewed and analyzed for eligibility; 40 citations fulfilled the inclusion criteria, 11 of which were randomized controlled trials. In total, 15 of the articles specifically looked at PIOD whereas the other 25 included other etiologies for olfactory dysfunction.

CONCLUSIONS

The Clinical Olfactory Working Group members made an overwhelming recommendation for olfactory training; none recommended monocycline antibiotics. The diagnostic role of oral steroids was discussed; some group members were in favor of vitamin A drops. Further research is needed to confirm the place of other therapeutic options.

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.

Topographical distribution of trigeminal receptor expression in the nasal cavity

BACKGROUND

Topographical differences in trigeminal receptor distribution of the nasal cavity has been investigated so far indirectly using various agonists to stimulate receptors in different locations. However, polymodal activation of trigeminal receptors poses difficulties in such investigation. The aim of our study was to examine the distribution of trigeminal receptor mRNA expression using quantitative PCR.

METHODOLOGY

A prospective study was performed in 18 healthy volunteers. Mucosal biopsies were obtained from five different endonasal locations (covering the anterior, posterior and lateral nasal cavity) for receptor mRNA quantification by means of RTPCR.

RESULTS

The highest overall level of RNA expression was found for TRPV1, followed by ACCN3, TRPA1 and TRPM8. Identical distribution pattern could be shown for each investigated area of the nasal cavity. Highest overall receptor density was found in the posterior septum due to high TRPV1 and ACCN3 receptor expression.

CONCLUSIONS

For the first time, we demonstrate a distinct trigeminal receptor RNA distribution pattern of the nasal mucosa. The highest overall distribution level was found in the posterior nose.

Electro-olfactogram Responses Before and After Aversive Olfactory Conditioning in Humans

The aim of the present study was to investigate whether repetitive aversive odor conditioning induced changes at the level of the peripheral olfactory system in humans. A total of 51 volunteers participated. A pair of indistinguishable odor enantiomers [(+)-rose oxide and (-)-rose oxide] were used as stimuli. During the pre-conditioning, participants' ability to discriminate between the two odors was assessed using a three-alternative, forced-choice discrimination test. In addition, electro-olfactograms (EOG) from the olfactory epithelium were recorded. Participants underwent three conditioning sessions on consecutive days. The experimental group received an electrical stimulus to the forearm only following (+)-rose oxide presentation, whereas its enantiomer sibling was never paired with the aversive stimulus; the control group did not receive any electrical stimulation. During the post-conditioning session, their ability to discriminate the two enantiomers was assessed again using the discrimination test and EOG recordings were obtained similarly to the pre-conditioning session. Results showed significant differences in the peripheral electrophysiological responses between the conditioned and the unconditioned stimulus, demonstrating contextually induced changes at the level of the first neuron in the olfactory system.

Trigeminal sensitivity in chronic rhinosinusitis: topographical differences and the effect of surgery

INTRODUCTION

Little is known on endonasal trigeminal sensitivity in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). The aim of our study was to investigate changes in trigeminal sensitivity in patients with CRSwNP and the effect of functional endoscopic sinus surgery (FESS) on trigeminal perception.

METHODS

A prospective study was performed to investigate the trigeminal sensitivity at three different locations within the nose (anterior septum, anterior lateral wall, middle turbinate) using electrical stimuli. Therefore 45 CRSwNP patients were compared to 30 healthy subjects. Further, the effect of FESS was investigated in 31 patients before and 3 months after surgery.

RESULTS

CRSwNP patients had a significantly higher trigeminal threshold at all tested locations than healthy subjects. The lowest trigeminal detection threshold could be shown at the entrance of the nose in healthy subjects and in patients with CRSwNP. Three months after FESS a significant improvement of trigeminal detection threshold was observed at the anterior nasal septum.

CONCLUSION

Protective function of the trigeminal system is preserved in CRSwNP patients. FESS seems to show beneficial effects on restoring sentinel function at the entrance of the nose.

Olfaction in patients with allergic rhinitis: an indicator of successful MP-AzeFlu therapy

BACKGROUND

The purpose of this study was to investigate the effect of MP-AzeFlu on olfaction and the interaction between severity of allergic rhinitis and olfactory improvement after therapy.

METHODS

A prospective, multicenter, observational study was performed on 47 patients with persistent allergic rhinitis. Duration and severity of allergic rhinitis was diagnosed and classified using the modified Allergic Rhinitis and its Impact on Asthma (ARIA) criteria and the proof of allergen sensitization from positive skin-prick tests, specific immonoglobulin E (IgE) in serum, and nasal provocation response. Patients were treated with MP-AzeFlu (1 spray/nostril twice daily) over 3 months. Olfactory function was assessed at baseline and at 1 and 3 months of therapy using the "Sniffin' Sticks" test. In addition, a nasal symptom score was recorded on a visual analog scale (VAS) at each given time-point.

RESULTS

MP-AzeFlu was found to be associated with a significant improvement in TDI score, from 23.7 at baseline to 34.2 at 1 month (p < 0.001) and 37.1 at 3 months (p < 0.001) of treatment. Furthermore, a highly significant improvement of symptoms over time (p < 0.001; VAS at baseline: 84.3; 1 month: 32.4; 3 months: 26.2) could be demonstrated. Most importantly, there was a highly significant interaction between the severity of allergic rhinitis and olfactory function (p < 0.001) and VAS (p < 0.001).

CONCLUSION

MP-AzeFlu is associated with olfactory improvement in persistent allergic rhinitis patients. Further, the modified ARIA severity classification is an indicator of patients' olfactory function. Moreover, assessment of olfaction seems to be a reliable indicator of the clinical success of antiallergic/antiinflammatory therapy.

Olfaction in chronic rhinosinusitis: comparing two different endonasal steroid application methods

Limited olfactory improvement after topical steroid therapy in chronic rhinosinusitis (CRS) patients might result from restricted drug access to the olfactory cleft. The aim of our study was to investigate the difference between two methods to topically administer steroids with respect to olfaction: (1) conventional nasal spray and (2) a device using pressure and vibration to distribute steroid aerosol endonasally. A prospective study was performed in patients with olfactory impairment due to chronic rhinosinusitis with and without nasal polyps. While the first group used the conventional dexamethasone nasal spray, the second group used the device over a period of 12 days. Olfactory testing was done at 0, 2, and 8 weeks using Sniffin' Sticks test. A significant olfactory improvement was found after 2 weeks of treatment with either steroid (p = 0.005). However, there was no significant difference between the different methods of steroid application. There is a significant olfactory improvement in CRS patients following topical dexamethasone therapy, but no obvious superiority of one of the two ways to administer the steroid.

Olfactory Training Using Heavy and Light Weight Molecule Odors

Background

Repeated short-term exposure to odors is known to improve olfaction in patients with acquired olfactory dysfunction. The aim was to find out whether differences in molecular weight of odors used for olfactory training influences olfaction. We hypothesized a greater improvement following training with light weight molecule (LWM) odors.

Methods

A prospective study was performed in patients with posttraumatic (PTOL) and postviral olfactory loss (PVOL). Olfactory training was performed over a period of 5 months. One group ( n = 48) used four odors containing heavy weight molecules (HWM; >150 g/mol) and another ( n = 48) containing LWM (<150 g/mol). Olfaction was tested before and after the training using the Sniffin’ Sticks test.

Results

Olfactory training was associated with olfactory improvement, with the improvement in PVOL patients being three times greater than that seen in the PTOL group. Compared with LWM training, HWM training was associated with a significantly greater improvement in Phenyl Ethyl Alcohol (PEA) threshold scores in PVOL patients; however, no such improvement could be shown for other subtests or in PTOL patients.

Conclusion

Overall, training was associated with olfactory improvement. With the exception of threshold scores in PVOL, there were no significant differences between LWM and HWM groups.

Severe open subtalar dislocations. Long-term results

Fifteen adolescents and adults were assessed an average of eighteen years after a type-III open subtalar dislocation. There were ten lateral and five medial dislocations. Associated injuries included ten injuries of the tibial nerve, seven of which were complicated by causalgia; five ruptures of the posterior tibial tendon; five lacerations of the posterior tibial artery; twelve articular fractures involving the subtalar joint; three articular fractures of the talonavicular joint; three fractures of the talar dome; and three malleolar fractures. Osteonecrosis of the body of the talus was found in five of the fifteen patients. It was treated with a triple arthrodesis in all five patients, one of whom had a subsequent conversion to a pantalar arthrodesis. Subtalar arthrodesis was done, because of post-traumatic osteoarthrosis, in two other patients. On functional assessment at the long-term follow-up examination, all patients reported some pain in the ankle, nine had difficulty climbing stairs, fourteen had difficulty walking on uneven surfaces, and eleven wore modified shoes. The patients who had had a tarsal arthrodesis returned to their pre-injury occupation or to a less strenuous job. Four patients who had persistent causalgia did not return to work. We concluded that open subtalar dislocation is a distinctly severe injury and that only fair functional and poor anatomical results can be expected in most patients.

The use of magnetic resonance imaging in the diagnosis of pigmented villonodular synovitis

Although the clinical and radiographic features of pigmented villonodular synovitis (PVS) have been well described, diagnosis is often delayed and high rates of recurrence after synovectomy are reported. Magnetic resonance imaging (MRI) has been shown to be useful in the diagnosis of soft tissue masses. Three patients with biopsy-proven PVS and radiographs showing only effusion underwent MRI in the axial, coronal, and sagittal planes. The margins of the diseased synovium were best demonstrated on long TR/TE (T2-weighted) images. The synovium contained areas of void signal intensity felt to be due to hemosiderin, interspersed with increased signal from both inflammation and fat. In all cases, the margins of the diseased synovium were clearly delineated, allowing classification as nodular or diffuse. No appreciable change in signal intensity was seen when comparing nodular and diffuse forms. MRI is useful but not specific for PVS, since rheumatoid synovitis may show a similar signal pattern. However, MRI in patients with suspected PVS may decrease the time until diagnosis, aid in preoperative planning and obtaining adequate margins of resection, and may be a non-invasive method of long-term follow up for possible recurrence.

Bone-grafting in total hip arthroplasty for protrusio acetabuli. A follow-up note

The results of total hip arthroplasty with the use of medial and superior bone-graft augmentation in thirty-nine hips (thirty-two patients) that had protrusio acetabuli were previously reported after two to eight years (mean, 4.7 years) of follow-up. We followed the surviving patients for 10.9 to 17.4 years (mean, 12.8 years). The average Harris hip-rating was 72 points--an average drop of 17 points since the previous report. The average was 64 points for patients who had rheumatoid arthritis and 83 points for those who had another diagnosis. Radiographic evaluation demonstrated definite, probable, and possible loosening in about 20, 10, and 60 per cent of the hips, respectively. Of the six hips that had definite loosening, four (10 per cent of the total series) had progression of the protrusion (acetabular migration); operative revision was performed on two of those four hips and on two other hips, in which progression had ceased. Hips that had progressive protrusion demonstrated superior migration more often than medial migration. The rates of loosening and revision were similar to those in hips that did not have protrusio acetabuli. We concluded that augmentation of total hip arthroplasty with bone-grafting is effective in arresting the progression of protrusio acetabuli in most hips (90 per cent in our series).

Radiographic measurements in protrusio acetabuli

The radiographic data of 48 hips in 40 patients with painful, progressive protrusio acetabuli treated with cemented total hip arthroplasty and medial acetabular reinforcement using autologous or homologous bone grafts were reviewed. Twelve separate measurements were performed on the preoperative, postoperative, and most recent radiographs of each case to determine which measurements were the most useful in diagnosing protrusio acetabuli and in following preoperative and postoperative migration. The minimum follow-up period was 10 years (mean, 12.3 years). Vertical migration and horizontal distance, two measurements utilizing an X-Y coordinate system based on the acetabular teardrop, were found to be most useful. The cases with postoperative progression demonstrated vertical migration more often than medial migration.