ABSTRACT
Background: SARS-CoV-2 infection is accompanied by acute olfactory disturbance in as high as 70% of cases. This loss is associated with decreased olfactory bulb volume. As time passes, the anosmia tends to subside, but the OB volume decrease does not. Volume reductions in primary and secondary olfactory cortex are also seen following SARS-CoV-2 infection. Nevertheless, concurrent SARS-CoV-2 infection effects on olfactory discrimination, olfactory bulb volume, primary olfactory cortex and its targets have not been investigated. To explore this possibility, we measured olfactory discrimination, olfactory bulb volume, primary olfactory cortex and basal ganglia volume in patients who had SARS-CoV-2 infection more than 12 weeks previously, who were then divided into COVID and long-COVID groups on the basis of selfreported fatigue and concentration complaints. Method(s): This cross-sectional study included 25 post-infection and 19 demographically-matched, no-COVID control participants, we investigated effects on olfaction using NIH Toolbox Odor Identification Test and the Monell Smell Questionnaire. GM structure was assessed with voxel-based morphometry and manual delineation of high resolution (1mm3), T1- and T2-weighted MRI data. Linear regression was used to model group effects on GM structure, adjusting for age, sex, education and total intracranial volume. CAT12/SPM12 and R were used for image processing and statistical modeling. Result(s): Results. The NIH Toolbox Odor Identification Test failed to show differences among the groups. In contrast, the Monell Smell Questionnaire revealed persistently diminished and distorted smell in 50% of the long-COVID sample. Olfactory bulb volume was lower in the long-COVID group (p=0.02). Primary olfactory cortex volume was reduced in the long-COVID group (p=0.004). Caudate volume was also lower in the long-COVID group (p=0.04). Conclusion(s): Conclusions. In the absence of olfactory discrimination problems, long-COVID, but not COVID, patients experience persistent olfactory loss and distortion. These perceptual problems are associated with lower olfactory bulb, primary olfactory cortex, and caudate volume, suggesting that the effects of SARS-CoV-2 infection can extend beyond the olfactory periphery in some cases to affect central targets. (Figure Presented).
ABSTRACT
Hospital workers have increased exposure risk of healthcare-associated infections due to the frontline nature of their work. Olfactory dysfunction is highly prevalent. The objectives for this investigation are to study the prevalence of long-lasting olfactory dysfunction associated with COVID-19 infection in hospital workers during the first pandemic wave, to identify clinical characteristics and associated symptomatology, and to analyze how many patients with COVID-19 infection had developed olfactory dysfunction during infection and maintained a reduced olfactory function for approximately 10 weeks after diagnosis. Between June and July of 2020, a cross-sectional study was carried out at the Hospital Central de la Cruz Roja San José and Santa Adela in Madrid, Spain. One hundred sixty-four participants were included, of which 110 were patient-facing healthcare staff and 54 were non-patient-facing healthcare staff. Participants were split into three groups, according to COVID-19 diagnosis and presence of COVID-19 related olfactory symptomatology. Participants were asked to complete a structured online questionnaire along with Sniffin’ Stick Olfactory Test measurements. In this study, 88 participants were confirmed for COVID-19 infection, 59 of those participants also reported olfactory symptomatology. The prevalence of COVID-19 infection was 11.35%, and the prevalence for olfactory dysfunction was 67.05%. Olfactory dysfunction associated with COVID-19 infection leads to long-lasting olfactory loss. Objective assessment with Sniffin’ Stick Olfactory Test points to odor identification as the most affected process. Lemon, liquorice, solvent, and rose are the odors that are worst recognized. Mint, banana, solvent, garlic, coffee, and pineapple, although they are identified, are perceived with less intensity. The findings of this study confirmed a high prevalence of SARS-CoV-2 infection among the hospital workers.