Characteristics of the Anosmic Post-COVID-19 Olfactory Mucosa

Study Overview
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Brief Summary
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The present study aims to describe the structural tissue and cell characteristics of the olfactory mucosa in patients with persistent anosmia (≥2 years) due to COVID-19 or head-trauma, in comparison to healthy individuals with intact olfactory function. In order to avoid possible age-related degenerative changes in the neuro-epithelium, both patients and controls are between 25 and 35 years of age.

Official Title
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Characteristics of the Anosmic Post-COVID-19 Olfactory Mucosa

Conditions
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Anosmia, COVID-19, Head Injury

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Legally competent to vouch for their own study participation. Informed and written consent for participation in this study. Study group 1 (Post-COVID anosmia) Diagnosed with persistent anosmia for approximately two years concurring with positive SARS-CoV-2 PCR-test between 2019 and 2020. Sniffin'sticks test with a threshold-discrimination-identification-score(TDI)≤16 Between 25 and 35 years of age. Study group 2 (Post-trauma anosmia) Diagnosed with persistent anosmia for approximately two years concurring with head trauma. Sniffin'sticks test with a threshold-discrimination-identification-score(TDI)≤16 Between 25 and 35 years of age. Study group 3 (Controls): Between 25 and 35 years of age. Undergoing reposition of a nasal fracture in general anaesthesia Exclusion Criteria: <25 years of age. >35 years of age. Chronic rhinosinusitis with/without polyps. Nasal cancer. Presence of viral or bacterial rhinosinusitis. Uncontrolled allergic rhinosinusitis. Coagulation deficiencies, e.g. haemophilia. Use of anticoagulants. Not able to undergo general anaesthesia. Pregnancy. Any use of nasal detumescence drugs ≤2 weeks before biopsy. Any use of nasal steroids ≤3 months before biopsy. Use of nasal inhaled recreational drugs ≤3 month before biopsy. Participants not able to communicate in Danish or English. Major Depression Inventory (MDI) score ≥27 [49, 50] Mini Mental State Examination (MMSE) score ≤ 26 [51] Study group 1 (Post-COVID anosmia) Anosmia for less than two years or more than two and a half years. No positive SARS-CoV-2 PCR-test concurring with olfactory dysfunction. History of olfactory dysfunction before COVID-19 infection. Study group 2 (Post-trauma anosmia) Anosmia for less than two years or more than approximately two-three years. Anosmia without concurring with head trauma History of prior olfactory dysfunction before head trauma. Study group 3 (Controls) 1. Known olfactory dysfunction.

Ages Eligible for Study
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Minimum Age: 25 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Control<br> | |
| COVID-19 related anosmia<br> | |
| Head-trauma related anosmia<br> | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Histological evaluation |  | 2023 | 
| Immunohistochemical evaluation |  | 2023 |