The relationship between persistent olfactory dysfunction associated with COVID-19 and olfactory bulb morphology

Olfactory disorders are more relevant than ever in the era of the pandemic of the new coronavirus infection (COVID-19). According to statistical data, about 60 % of patients complain of olfactory dysfunction (OD) in the acute period, while 6.2 % of patients note that complaints persist for more than a month after recovery from COVID-19. However, no more than 5 % of those with persistent OD seek medical help. Currently, the diagnosis of OD is difficult due to the lack of a single examination protocol. Attempts have been made to compare the MRI data of the olfactory nerve and the severity of OD, based on changes in the volume of the olfactory bulb (OB), at the same time, one should not forget that in addition to the volume of OB, it is possible to assess the morphology of OB, which changes in response to direct respiratory exposure. The article provides up-to-date information, including an assessment of 15 meta-analyses on the features of MRI diagnosis of OD associated with COVID-19, as well as the results of the authors' personal experience.