COVID-19-induced anosmia associated with olfactory bulb atrophy

Abstract

As the global COVID-19 pandemic evolves, our knowledge of the respiratory and non-respiratory symptoms continues to grow. One such symptom, anosmia, may be a neurologic marker of coronavirus infection and the initial presentation of infected patients. Because this symptom is not routinely investigated by imaging, there is conflicting literature on neuroimaging abnormalities related to COVID-19-related anosmia. We present a novel case of COVID-19 anosmia with definitive olfactory bulb atrophy compared with pre-COVID imaging. The patient had prior MR imaging related to a history of prolactinoma that provided baseline volumes of her olfactory bulbs. After a positive diagnosis of COVID-19 and approximately 2 months duration of anosmia, an MRI was performed that showed clear interval olfactory bulb atrophy. This diagnostic finding is of prognostic importance and indicates that the olfactory entry point to the brain should be further investigated to improve our understanding of COVID infectious pathophysiology.

Scientific publishing during the COVID-19 pandemic

“…August followed with a pictoral review of "Bilateral lesions of the basal ganglia and thalami (central grey matter)" that included COVID-19-associated acute necrotizing encephalopathy [2]. Although Neuroradiology publishes only exceptional case reports, we presented in September a patient with "COVID-19-induced anosmia associated with olfactory bulb atrophy," who had a pre-COVID MRI for comparison [3]. This report supports the view that the virus may infect olfactory epithelial support cells.…”

Gross and Histopathology of COVID-19 With First Histology Report of Olfactory Bulb Changes

“…To our knowledge, this is the first report of histological changes in the olfactory bulbs. So far involvement of the bulb has only been confirmed on imaging modalities, showing either edema or atrophy [18,19]. The development of severe inflammation and neuronal degeneration and necrosis as a result of the viral infection may explain why anosmia is with a sudden onset and takes longer than the other symptoms to resolve [15,16,19].…”

“…So far involvement of the bulb has only been confirmed on imaging modalities, showing either edema or atrophy [18,19]. The development of severe inflammation and neuronal degeneration and necrosis as a result of the viral infection may explain why anosmia is with a sudden onset and takes longer than the other symptoms to resolve [15,16,19]. There is already growing evidence in the field of adult olfactory bulb neurogenesis for the production of new neurons, which replace and integrate into existing chains [20].…”

COVID‑19‑associated meningoencephalitis: A care report and literature review

“…However, the clinical characteristics of COVID-19-associated meningitis/encephalitis remain to be defined. Anosmia/dysgeusia has been reported by COVID-19 patient (8)(9)(10). This phenomenon provided a hypothesis that COVID-19-associated CNS infection is manifests through a nasopharyngeal route.…”