Reduced olfactory bulb volume accompanies olfactory dysfunction after mild SARS-CoV-2 infection

Area of Science:

• Neurology
• Radiology
• Infectious Diseases

Background:

• Smelling impairment is a common yet poorly understood symptom of COVID-19.
• Understanding the determinants of olfactory dysfunction is crucial for patient management.

Purpose of the Study:

• To investigate the association between olfactory bulb volume and the clinical course of COVID-19-related smelling impairment.
• To identify potential imaging biomarkers for olfactory dysfunction in COVID-19 convalescents.

Main Methods:

• A large-scale magnetic resonance imaging (MRI) study analyzed data from 233 non-vaccinated COVID-19 convalescents.
• Baseline MRI, neuropsychological testing, and olfactory function questionnaires were performed.
• Follow-up assessments included quantitative olfactometric testing using Sniffin' Sticks.

Main Results:

• Prevalence of self-reported olfactory dysfunction decreased from 67.1% during acute infection to 17.5% at follow-up.
• Individuals with persistent olfactory dysfunction had significantly smaller olfactory bulb volumes at baseline.
• Baseline olfactory bulb volume predicted olfactometric scores at follow-up, while neuropsychological performance did not show a significant association.

Conclusions:

• Olfactory bulb volume is associated with long-term smelling dysfunction in individuals recovered from COVID-19.
• Olfactory bulb integrity serves as a potential surrogate marker for diagnosing and managing post-COVID-19 olfactory impairment.
• These findings may inform rehabilitation strategies for patients experiencing persistent smell loss.