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A Free-breathing fMRI Method to Study Human Olfactory Function
Published on: July 30, 2017
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Comparative imaging study of patients with persistent olfactory dysfunction due to mild COVID-19 using structural and
David Dylan García-Meléndez1, Raquel Moreno Presa1, Pilar Quintana Castro1
1University Hospital of Toledo, Av. del Río Guadiana, 45007 Toledo, Spain.
Medicina Clinica
|July 3, 2024
Summary
Persistent post-COVID olfactory dysfunction was studied in mild COVID-19 cases. Functional MRI revealed no entorhinal cortex activation in patients, unlike controls, despite normal brain morphology.
Area of Science:
- Neurology
- Neuroimaging
- Otorhinolaryngology
Background:
- Persistent olfactory dysfunction is a common sequela of COVID-19, with unclear pathophysiology.
- Neuroimaging studies are crucial for understanding the underlying mechanisms of post-COVID smell loss.
Purpose of the Study:
- To investigate the neuroimaging correlates of persistent olfactory dysfunction after mild COVID-19.
- To compare olfactory bulb and brain activity in patients with post-COVID smell loss versus healthy controls.
Main Methods:
- A cohort of 8 patients with >1 month of olfactory dysfunction post-mild COVID-19 and 2 controls were assessed.
- Olfactory function was evaluated using the Sniffin' Sticks Olfactory Test.
- Brain and olfactory bulb morphology via MRI and functional MRI (fMRI) were performed.
Main Results:
- No morphological differences in the brain or olfactory bulb were observed between patients and controls.
- Functional MRI showed no entorhinal cortex activation in patients, contrasting with controls.
- Secondary olfactory area activation differed: orbitofrontal (25% vs 100%), basal ganglia (25% vs 50%), and insula (38% vs 0%) in patients vs controls.
Conclusions:
- Post-COVID olfactory dysfunction is not associated with morphological brain changes.
- Functional MRI reveals impaired entorhinal cortex activation in patients with persistent post-COVID smell loss.
- Altered activation patterns in secondary olfactory areas may contribute to olfactory deficits after COVID-19.
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