Chemosensory function assessed with psychophysical testing and event-related potentials in patients with atrophic rhinitis

Rhinology in review: from COVID-19 to biologicals

We look back at the end of what soon will be seen as an historic year, from COVID-19 to real-world introduction of biologicals influencing the life of our patients. This review describes the important findings in Rhinology over the past year. A large body of evidence now demonstrates loss of sense of smell to be one of the most common symptoms of COVID-19 infection; a meta-analysis of 3563 patients found the mean prevalence of self-reported loss to be 47%. A number of studies have now shown long-term reduced loss of smell and parosmia. Given the high numbers of people affected by COVID-19, even with the best reported recovery rates, a significant number worldwide will be left with severe olfactory dysfunction. The most prevalent causes for olfactory dysfunction, besides COVID-19 and upper respiratory tract infections in general, are trauma and CRSwNP. For these CRSwNP patients a bright future seems to be starting with the development of treatment with biologics. This year the Nobel prize in Medicine 2021 was awarded jointly to David Julius and Ardem Patapoutian for their discoveries of receptors for temperature and touch which has greatly enhanced our understanding of nasal hyperreactivity and understanding of intranasal trigeminal function. Finally, a new definition of chronic rhinitis has been proposed in the last year and we have seen many papers emphasizing the importance of endotyping patients in chronic rhinitis and rhinosinusitis in order to optimise treatment effect.

Trigeminal impairment in treatment-refractory chronic nasal obstruction

BACKGROUND

Patients with anatomically unexplained, chronic nasal obstruction (CNO) that is refractory to medical treatment pose a challenge for clinicians. A surgical solution, addressing mechanical obstacles, is unsuited for these patients. CNO may result from disrupted airflow perception due to activation of the intranasal trigeminal system; therefore, aim of this study is to evaluate if intranasal trigeminal function of these CNO patients is decreased.

METHODS

In this retrospective cross-sectional study, we compared 143 CNO patients and 58 healthy volunteers, between 18 to 80 years old. We assessed nasal patency by means of rhinomanometry (RM) and measured susceptibility of intranasal trigeminal system by the trigeminal lateralization task (TLT).

RESULTS

TLT scores were significantly lower in CNO patients compared to controls (p less than 0.001), but RM scores were not different between groups. Accordingly, TLT allowed to identify CNO patients with an accuracy of the area under the curve (AUC) of 0.78, while the value for RM was at chance (AUC=0.47). CNO patients showed normal reaction to vasoconstrictive agents with significantly lower RM values after Xylomethazoline application.

CONCLUSION

Results suggest that reported nasal obstruction in CNO patients without any obvious anatomical obstacle and resistant to medical treatment may be linked to decreased perception of nasal airflow rather than physical obstruction. In this sub-set of CNO patients, trigeminal testing more adequately reflects the reported obstruction than nasal resistance assessment does. In future studies, the relation of the trigeminal status and the subjective sensation of nasal obstruction needs to be addressed with validated patient rated outcome measures (PROMs).

Central Nervous System Processing of Floral Odor and Mother's Milk Odor in Infants

Newborns have a functioning sense of smell at birth, which appears to be highly significant for feeding and bonding. Still, little is known about the cerebral odor processing in this age group. Studies of olfactory function relied mostly on behavioral, autonomic, and facial responses of infants. The aim of the present study was to investigate central odor processing in infants focusing on electroencephalography (EEG)-derived responses to biologically significant odors, namely a food and a non-food odor. A total of 21 term-born, healthy infants participated (11 boys and 10 girls; age range 2-9 months, mean 5.3 ± 2.2 months). Odor stimuli were presented using a computer-controlled olfactometer. Breast milk was used as food odor. Farnesol was presented as a non-food odor. In addition, odorless air was used as a control stimulus. Each stimulus was presented 30 times for 1 s with an interstimulus interval of 20 s. EEG was recorded from 9 electrodes and analyzed in the frequency domain. EEG amplitudes in the delta frequency band differed significantly after presentation of food (breast milk) odor in comparison to the control condition and the non-food odor (farnesol). These changes were observed at the frontal recording positions. The present study indicates that central odor processing differs between a food and a non-food odor in infants. Results are interpreted in terms of focused attention towards a physiologically relevant odor (breast milk), suggesting that olfactory stimuli are of specific significance in this age group.

Olfaction in Primary Atrophic Rhinitis and Effect of Treatment

Objective

To assess olfactory and clinical morbidity in primary (idiopathic)–type atrophic rhinitis and its course following treatment.

Study Design

Prospective nonrandomized controlled cohort study with follow-up.

Setting

Department of Otorhinolaryngology and Head and Neck Surgery of a university hospital (tertiary heath care center).

Methods

Sixty-one patients with atrophic rhinitis underwent assessment of clinical severity with baseline olfaction with the Brief Smell Identification test, while the improvement of their status following surgical versus nonsurgical treatment was further assessed.

Results

Olfaction was universally deranged with bimodal age presentation and female predominance (61%). Clinical improvement was significantly associated with surgical treatment but did not reveal any relation with up-front severity of disease. A near-significant association of age with severity did not reveal significance when stratified by age group. Baseline olfaction or its change following treatment did not reveal any significance with severity of disease or clinical improvement. Radiologic atrophy also did not reveal any significant relation with severity criteria.

Conclusions

Olfactory functions as compared with clinical parameters provided better reflection of underlying (systemic) pathology with environmental interaction, while later it mainly signified localized condition. Accordingly, olfaction was affected early and recovered slowly (or not at all), independent of clinical morbidity, which in turn is affected rather late but recovers early. Olfactory dysfunction at the initial stage may be a surrogate marker of potential worsening clinical condition, since bacteria often superinfect underlying susceptible nasal environment. While surgery mainly improved clinical parameters without affecting olfaction directly, a true improvement would include recovery of both.

Erkennungsraten von chemosensorisch evozierten Potenzialen bei gesunden und anosmischen Erwachsenen

Hintergrund Die Detektionsrate von olfaktorischen chemosensorischen ereignisbezogenen EEG-Potenzialen (oCSERP) und trigeminalen chemosensorischen ereignisbezogenen EEG-Potenzialen (tCSERP) ist auch abhängig vom Reizstoff und vom Beurteiler der gemittelten EEG-Kurven.

Methodik Es wurden bei 45 Probanden mit altersentsprechendem Riechvermögen (NP) und 20 Anosmikern (AN) oCSERP (Reizung mit Schwefelwasserstoff, H2S 6 ppm, und Phenylethylalkohol, PEA 30 % v/v) sowie tCSERP (Reizung mit CO2 20–60 % v/v, intensitätsnormiert) standardmäßig abgeleitet. Die gemittelten EEG-Kurven wurden von 2 Untersuchern kategorisiert in: CSERP erkennbar, kein CSERP erkennbar, Artefakt. Untersucher 2 war in Bezug auf die Gruppenzuordnung der Probanden verblindet, Untersucher 1 hingegen nicht.

Ergebnisse AN benötigten im Vergleich zu NP höhere trigeminale Reizkonzentrationen bei gleichem Intensitätsrating. Die Aufmerksamkeit (Trackingspiel) verschlechterte sich im Testverlauf nicht. Die Detektionsrate von H2S-CSERP war höher als die von CO2-CSERP und PEA-CSERP. Die Übereinstimmung der Detektionsraten zwischen beiden Untersuchern bei H2S-CSERP war höher als bei CO2-CSERP und bei PEA-CSERP.

Schlussfolgerung Für die standardmäßige Ableitung von oCSERP reicht gewöhnlich eine Reizung mit H2S. Auf eine Stimulation mit PEA und CO2 wie auch auf einen verblindeten zweiten Untersucher kann verzichtet werden.

Intranasal trigeminal function in patients with empty nose syndrome

OBJECTIVES/HYPOTHESIS

Trigeminal nerve mediates the perception of nasal airflow. This study examines whether impaired intranasal trigeminal function is a part of the paradoxical nasal obstruction sensation in patients with empty nose syndrome (ENS).

STUDY DESIGN

Prospective case-control study in a tertiary hospital.

METHODS

Three groups were examined: 1) ENS patients with previous bilateral near total inferior turbinectomy, 2) patients who underwent near total inferior turbinate removal (ITR) without ENS symptoms, and 3) control participants. All participants examined with active anterior rhinomanometry, olfactory testing (extended Sniffin' Sticks test), and trigeminal testing (lateralization task using menthol and odorless solvent).

RESULTS

Seventy-one participants were included (21 ENS patients, 18 ITR patients, and 31 controls). Analyses revealed that ENS patients had significantly lower scores on trigeminal lateralization testing than the ITR group and controls. The ENS group had also significantly lower scores in olfactory testing than controls. No statistical differences were found in rhinomanometry between groups. The gender factor was not associated with the chemosensory testing; however, this was not the case with the age factor, as trigeminal test results were negatively correlated.

CONCLUSIONS

This study demonstrates significantly impaired intranasal trigeminal function in ENS patients when compared with ITR patients and controls. Further prospective studies are needed to clarify the role of preoperative trigeminal function of these patients and the contribution of surgery to this impairment.

LEVEL OF EVIDENCE

3b. Laryngoscope, 127:1263-1267, 2017.

Olfaction in Chronic Rhinosinusitis

Olfactory dysfunction is a frequent complaint in chronic rhinosinusitis patients and has a significant impact on quality of life. Therefore, it is essential that clinicians are aware of the importance of olfactory dysfunction in chronic rhinosinusitis (CRS) patients and know how to deal with it. Notably, the evaluation of olfactory function (i.e., using psychophysical testing) and imagery of olfactory bulb play an important role in the evaluation of patients and give essential information about the "baseline" olfactory function. Because the high impact of olfactory function on quality of life and medical and/or surgical treatment should be proposed to patients. However, it remains difficult to predict the outcome of treatment as well as long-term efficacy. The first section of this review is dedicated to the assessment of olfactory function. Secondly, we will discuss the etiopathology of olfactory dysfunction in CRS with and without nasal polyps. Finally, we will review literature findings about the efficacy of different treatments on olfactory function.