Acute anosmia in neuromyelitis optica spectrum disorder.

The cardinal features of neuromyelitis optica spectrum disorder (NMOSD) are optic neuritis, longitudinal extensive transverse myelitis and area postrema syndrome. Olfactory dysfunction is not listed as a feature in the NMOSD diagnostic criteria. Here, we present an aquaporin-4 antibody positive patient who, in addition to classical features of NMOSD, developed acute anosmia with magnetic resonance imaging (MRI) evidence of olfactory bulb abnormalities. While the association of anosmia and NMOSD has been rarely noted previously, to our knowledge, no prior cases have found this to be one of the presenting features of a relapse nor have they identified acute radiological correlates.