Magnetic resonance spectroscopy findings of brain olfactory areas in patients with COVID-19-related anosmia: A preliminary comparative study

Objectives: 2019 novel coronavirus disease (COVID-19) infection is commonly associated with olfactory dysfunctions, but the basic pathogenesis of these complications remains controversial. This study seeks to evaluate the value of magnetic resonance spectroscopy (MRS) in determining the molecular neurometabolite alterations within the main brain olfactory areas in patients with COVID-19-related anosmia.

Methods: In a cross-sectional study, seven patients with persistent COVID-19-related anosmia (mean age: 29.57 years) and seven healthy volunteers (mean age: 27.28 years) underwent MRS in which N-acetyl-aspartate (NAA), choline (Cho), creatine (Cr), and their ratios were measured in the anterior cingulate cortex, dorsolateral prefrontal cortex, orbitofrontal cortex (OFC), insular cortex, and ventromedial prefrontal cortex. Data were analyzed using TARQUIN software (version 4.3.10), and the results were compared with an independent sample t-test and nonparametric Mann-Whitney test based on the normality of the MRS data distribution.

Results: The mean duration of anosmia before imaging was 8.5 months in COVID-19-related anosmia group. MRS analysis elucidated a significant association between MRS findings within OFC and COVID-19-related anosmia (P _disease < 0.01), and NAA was among the most important neurometabolites (P _interaction = 0.006). Reduced levels of NAA (P < 0.001), Cr (P < 0.001) and ^NAA/_Cho ratio (P = 0.007) within OFC characterize COVID-19-related anosmia.

Conclusions: This study emphasizes that MRS can be illuminating in COVID-19-related anosmia and indicates a possible association between central nervous system impairment and persistent COVID-19-related anosmia.