Bilateral transient olfactory bulb edema during COVID-19-related anosmia

An asymptomatic 27-year-old man was diagnosed with coronavirus disease 2019 (COVID-19) by occupational medicine after contagion (reverse transcription polymerase chain reaction [RT-PCR]). Four days after the diagnosis, he experienced complete anosmia and dysgeusia.(1) On day 7, 1.5T MRI showed signs of bilateral olfactory bulb edema on 3D constructive interference in steady state T2-weighted imaging, demonstrated by severe enlargement(2) (left: 73 mm(3), right: 64 mm(3)) and an abnormally high signal intensity (figure). Olfactory clefts showed mild edema. The olfactory pathways, including the cortical projections (fluid-attenuated inversion recovery and diffusion-weighted imaging not shown), were normal. Sensory recovery and negative RT-PCR (positive on days 1, 2, and 10) appeared on day 14. MRI on day 24 confirmed the normalization of olfactory bulb signal and volumes (left: 22 mm(3), right: 17 mm(3)).