Isolated olfactory cleft involvement in SARS-CoV-2 infection: prevalence and clinical correlates

Purpose: Smell alterations are a symptom of COVID-19 and have been associated with olfactory cleft mucosal thickening (OCMT). Although their pathogenesis is unclear, evidences link them to viral neuroinvasive potential. This study aims at estimating the prevalence of OCMT in CT scans of COVID-19 patients and investigating its clinical correlates. Methods: In a single-institution retrospective cross-sectional study, we included all patients hospitalized for COVID-19 undergoing head CT scan for any reason. Exclusion criteria were history of recent head trauma or chronic rhinosinusitis; opacification > 2 mm in any sinonasal space other than the olfactory cleft; CT performed during/after invasive ventilation or feeding via nasogastric tube. We recorded the prevalence of OCMT and related it to age, sex, need for invasive ventilation during hospital stay, outcome, length of hospital stay, diffusion of lung SARS-CoV-19 lesions and outcome. Results: 63 eligible patients were identified (39 male, 24 female; median age 77.82 ± 17.77 years). OCMT was identified in 16 patients (25.4%; 95% CI 15.3-37.9%). Patients with OCMT had longer hospital stays (median 16 ± 4 vs. 9 ± 14.5 days, p = .009, Mann-Whitney U test) and required invasive ventilation more frequently than patients without mucosal thickening (OR 4.89, 95% CI 0.96-24.89, p = .063, Fisher's test). No other difference was observed. Conclusion: OCMT affects nearly one in four patients hospitalized for COVID-19. It is associated with a worse disease course irrespective of age, sex and diffusion of lung lesions, although with no direct effect on survival.