Abstract
Coexisting myasthenia gravis and neuromyelitis optica spectrum disorder was reported as a rare association, with only 26 reported cases in the literature. The authors report the case of a middle-aged Chinese woman with bilateral recurrent optic neuritis and seropositive ocular myasthenia gravis who was subsequently diagnosed with neuromyelitis optica spectrum. She was tested seropositive for the neuromyelitis optica immunoglobulin G (NMO-IgG) and had elevated antinuclear antibody titres, but workup for other autoimmune disorders were negative. She was subsequently prescribed with azathioprine and pyridostigmine, and showed good control of both autoimmune disorders. To the best of the authors' knowledge, this is the first reported case in the literature of a Chinese patient with seropositivity for both anti-acetylcholine receptor and NMO-IgG without a thymic disorder. Testing of NMO-IgG may be considered in patients with optic neuritis with underlying autoimmune disorders even in the absence of transverse myelitis for the detection of associated neuromyelitis optica spectrum disorders.