Neurosensory Rehabilitation and Olfactory Network Recovery in COVID-19-related Olfactory Dysfunction

Abstract BackgroundNon-conductive olfactory dysfunction (OD) is an important extra-pulmonary manifestation of coronavirus disease 2019 (COVID-19). Prolonged COVID-19-related OD is a serious neurosensory disability. Treatment for the restoration of smell is urgently needed.Case presentationTwo patients presenting with prolonged COVID-19-related OD underwent structural and resting-state functional magnetic resonance imaging (rs-fMRI) brain scans. Two healthy controls were recruited for radiological comparison. One patient received olfactory treatment (OT) by the combination of oral vitamin A and smell training via the novel electronic portable aromatic rehabilitation (EPAR) diffusers. After four-weeks of OT, clinical recuperation of smell was correlated with interval increase of bilateral OB volumes [right: 22.5mm3 to 49.5mm3 (120%), left: 37.5mm3 to 42mm3 (12%)] and the enhancement of mean olfactory functional connectivity [0.09 to 0.15 (66.6%)]. ConclusionsOlfactory network functional defects and OB volume loss were identified in patients presenting with prolonged COVID-19-related OD. Preliminary evidence demonstrated that the combination of oral vitamin A and smell training may induce neurogenesis at the olfactory apparatus and achieve olfactory neurosensory rehabilitation. This observation should be validated in large scale randomized–controlled trials.