Smell and central olfactory pathways: study of the changes caused by COVID19 by 7 Tesla Nuclear Magnetic Resonance

• Grant number: 22/03639-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2022
• End date: May 31, 2023
• Field of knowledge: Health Sciences - Medicine - Psychiatry
• Principal Investigator: Fabio de Rezende Pinna
• Grantee: Débora Faciochi Cassol
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

COVID19 was declared a global pandemic in March 2020 by the World Health Organization (WHO). In this context, Chemosensory Changes of Smell and taste have emerged as prevalent symptom. Olfactory alterations usually present at the beginning of COVID19 cases, being the first symptom in 42% of cases and only symptom in 8.6% of patients. Nuclear Magnetic Resonance (MRI) is an important tool for the smell evaluation, and many changes were found in exams of post-COVID19 patients. However, due to the scarcity and limitation of the current literature, studies with few patients and without control groups, it is still not possible to say if there is a pattern of injury and its responsibility in smell changes in post-COVID19 patients. Thus, considering the courses taken by the SARS-CoV-2 pandemic, an imaging study with objective clinical correlation is essential to better understand the underlying pathogenesis of this chronic disorder without well-established effective therapy. Thus, our project aims to evaluate pathological patterns in the olfactory bulb and central olfactory pathways of patients with persistent dysosmias after COVID19, via a 7 Tesla Magnetic Resonance study. Secondarily, it is intended to characterize the lesions, hypothesize pathophysiological mechanisms of post-COVID19 dysosmias and describe the radiological anatomy of the central olfactory pathway. Methodologically, we propose an observational study of patients enrolled in the smell disorders outpatient clinic of HCFMUSP, with dysosmias resulting from COVID19, with chronicity (> 2 months) of symptoms, refractory to the recommended therapy. The individuals will be divided into three groups: 1 - patients with anosmia or severe hyposmia; 2 - patients with persistent parosmia, regardless of the coexistence of other dysosmias; 3 - asymptomatic, normosmic patients with no history of previous olfactory disorder or documented infection by COVID19; with 20 patients in each arm of the study, totaling 60 participants. Adult patients between 18 and 60 years old, of both sexes, enrolled in the smell disorders outpatient clinic will be recruited. Patients with previous sinusopathy/rhinitis, submitted to nasosinusal surgery or head and neck radiotherapy, patients with contraindications to the MRI exam and pregnant will be excluded. For classification of olfactory disorders, the adapted Connecticut olfactory test (CCCRC) tool will be used. For diagnostic confirmation, we will use RT-PCR test for SARS-CoV-2 performed at least 3 months before joining the study.The study will happen on Thursdays, from March 2022 to March 2023, in an outpatient setting at HCFMUSP and at the FMUSP Autopsy Room Image Platform (PISA), where the ultra-high MRI equipment magnetic field: 7T Magnetom (SIEMENS) is installed, to study the region of the olfactory slit, olfactory bulb and central olfactory pathways. (AU)