Rhinology in review: from COVID-19 to biologicals

Optogenetics Neuromodulation of the Nose

Recently developed optogenetic technology, which allows high-fidelity control of neuronal activity, has been applied to investigate the neural circuits underlying sensory processing and behavior. The nasal cavity is innervated by the olfactory nerve and trigeminal nerve, which are closely related to common symptoms of rhinitis, such as impairment of smell, itching, and sneezing. The olfactory system has an amazing ability to distinguish thousands of odorant molecules at trace levels. However, there are many issues in olfactory sensing mechanisms that need to be addressed. Optogenetics offers a novel technical approach to solve this dilemma. Therefore, we review the recent advances in olfactory optogenetics to clarify the mechanisms of chemical sensing, which may help identify the mechanism of dysfunction and suggest possible treatments for impaired smell. Additionally, in rhinitis patients, alterations in the other nerve (trigeminal nerve) that innervates the nasal cavity can lead to hyperresponsiveness to various nociceptive stimuli and central sensitization, causing frequent and persistent itching and sneezing. In the last several years, the application of optogenetics in regulating nociceptive receptors, which are distributed in sensory nerve endings, and amino acid receptors, which are distributed in vital brain regions, to alleviate overreaction to nociceptive stimuli, has gained significant attention. Therefore, we focus on the progress in optogenetics and its application in neuromodulation of nociceptive stimuli and discuss the potential clinical translation for treating rhinitis in the future.

Late olfactory bulb involvement in COVID-19

Transient or persistent hypo-anosmia is common in SARS‑CoV‑2 infection but olfactory pathway late-term morphometric changes are still under investigation. We evaluated late olfactory bulb (OB) imaging changes and their correlates with the olfactory function in otherwise neurologically asymptomatic COVID-19 patients. Eighty-three subjects (mean-age 43 ± 14 yr; 54 females; time-interval infection/MRI: 129±68 d) were affected by asymptomatic to mild COVID-19 in 2020 and 25 healthy controls (mean-age 40 ± 13 yr; 9 females) underwent 3T-MRI and olfactory function evaluation through anamnestic questionnaire and Sniffin' Sticks. Exclusion criteria were intensive care treatment or neurological involvement other than olfaction. Maximal OB area was measured blindly on high-resolution coronal T2w images by 2 observers. Patients were subdivided into (i) persistently hypo/anosmic, (ii) recovered normosmic, and (iii) never complaining smell dysfunction with proven normal olfactory function. No significant differences were observed among patients' subgroups (P = 0.76). Intraobserver and interobserver reliability were high (r = 0.96 and 0.86). Former COronaVIrus Disease 19 (COVID-19) patients had decreased mean maximal OB area than controls (6.52 ± 1.11 mm2 vs. 7.26 ± 1.17 mm2, P = 0.008) even when considering persistently hypo-anosmic (6.46 ± 0.90, P = 0.006) or normosmic patients at MRI (6.57 ± 1.25, P = 0.04). SARS-CoV-2 infection is associated with mid/late-term morphological changes in the OB, regardless of presence or persistence of olfactory dysfunction. The long-term consequences on olfactory aging need to be further investigated including possible links with neurodegenerative disorders.

Efficacy of pentasodium diethylenetriamine pentaacetate in ameliorating anosmia post COVID-19

BACKGROUND

COVID-19 has been frequently demonstrated to be associated with anosmia. Calcium cations are a mainstay in the transmission of odor. One of their documented effects is feedback inhibition. Thus, it has been advocated that reducing the free intranasal calcium cations using topical chelators such as pentasodium diethylenetriamine pentaacetate (DTPA) could lead to restoration of the olfactory function in patients with post-COVID-19 anosmia.

METHODOLOGY

This is a randomized controlled trial that investigated the effect of DTPA on post-COVID-19 anosmia. A total of 66 adult patients who had confirmed COVID-19 with associated anosmia that continued beyond three months of being negative for SARS-CoV-2 infection. The included patients were randomly allocated to the control group that received 0.9 % sodium chloride-containing nasal spray or the interventional group that received 2 % DTPA-containing nasal spray at a 1:1 ratio. Before treatment and 30 days post-treatment, the patients' olfactory function was evaluated using Sniffin' Sticks, and quantitative estimation of the calcium cations in the nasal mucus was done using a carbon paste ion-selective electrode test.

RESULTS

Patients in the DTPA-treated group significantly improved compared to the control group in recovery from functional anosmia to hyposmia. Additionally, they showed a significant post-treatment reduction in the calcium concentration compared to the control group.

CONCLUSION

This study confirmed the efficacy of DTPA in treating post-COVID-19 anosmia.

Effect of intra-nasal nitrilotriacetic acid trisodium salt in lowering elevated calcium cations and improving olfactory dysfunction in COVID-19 patients

Purpose

An association between COVID-19 and olfactory dysfunction has been noted in many patients worldwide. The olfactory adaptation process leads to an increase in intracellular calcium cation levels. Nitrilotriacetic acid trisodium salt has high selective chelation for calcium cations from olfactory mucus. The aim of this work is to test the effect of an intranasal nitrilotriacetic acid trisodium salt to lower the elevated calcium cations in COVID-19 patients with relevant symptoms of olfactory dysfunction.

Methods

Fifty-eight COVID-19 adult patients with relevant symptoms of olfactory dysfunction were enrolled in a prospective randomized controlled trial. They received a nasal spray containing either 0.9% sodium chloride or 2% nitrilotriacetic acid trisodium salt. Olfactory function was assessed before and after treatment using the Sniffin’ Sticks test. Quantitative analysis of calcium cation concentration in nasal secretions was performed using a carbon paste ion-selective electrode.

Results

After the application of nitrilotriacetic acid trisodium salt compared to sodium chloride, a significant improvement from functional anosmia to healthy normosmia with significant decrease in calcium cation concentration was observed.

Conclusions

Further collaborative research is needed to fully investigate the effect of an intranasal nitrilotriacetic acid trisodium salt in the treatment of olfactory disorders.

RHINOSINUSITIS IN PATIENTS IN POST-COVID-19 PERIOD: ETIOLOGY, CLINICAL AND MORPHOLOGICAL CHARACTERISTICS

OBJECTIVE

The aim is to identify the etiology, clinical and morphological features of rhinosinusitis in patients in post-COVID-19 period.

PATIENTS AND METHODS

Materials and methods: In the present study, it was carried out the analysis of 11 cases of rhinosinusitis, which developed after COVID-19 infection. The diagnosis of rhi¬nosinusitis was established on the basis of anamnesis, clinical and laboratory examination, specialized instrumental examination (rhinoendoscopy, X-ray, magnetic resonance imaging, spiral and 3D computed tomography). All patients underwent endoscopic sanitation of the nasal cavity, expansion of the maxillary anastomosis, maxillary sinusotomy, sanitation of the maxillary sinuses and removal of pathologically altered tissues. Microbiological examination of the swab from the nasal cavity was carried out in all patients. Histological and morphometric research methods were used during the morphological study of surgical material. The nonparametric Mann-Whitney U test was used to compare the means in the groups.

RESULTS

Results: The conducted comprehensive study made it possible to identify chronic atrophic rhinosinusitis at the stage of exacerbation caused by associations of bacteria and fungi in patients in post-COVID-19 period. Among bacteria, the authors most often noted Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumonia, Streptococcus pneumonia and Enterococcus faecalis. Among fungi, there were Aspergillus, Candida, Mucor and Coccidioides. Fungal infection was characterized by invasion into the mucous membrane of the nose and paranasal sinuses. In patients in post-COVID-19 period the invasive bacterial-fungal chronic atrophic rhinosinusitis at the stage of exacerbation was predominantly bilateral, characterized by the involvement of several or all paranasal sinuses in the process. Patients with such pathology complained of periodic fever, headaches and malaise; nasal congestion and constant difficulty in nasal breathing; yellowish-greenish-reddish discharge from the nasal cavity, sometimes with a fetid odor; discomfort and pain in the area of paranasal sinuses; immobility of the eyeball, hyposmia or anosmia; reduction or complete loss of vision. Frequent risk factors for the development of invasive bacterial-fungal chronic atrophic rhinosinusitis at the stage of exacerbation in patients in post-COVID-19 period were the information about moderate or severe course of this infection in anamnesis; comorbidities (predominantly diabetes mellitus, hypertensive disease and ischemic heart disease).

CONCLUSION

Conclusions: The study conducted by the authors made it possible to identify the etiological, clinical and morphological features, as well as risk factors of rhinosinusitis in patients in post-COVID-19 period. This information will contribute to a better understanding of such pathology by the doctors and improve the diagnostic and treatment process.