Anti-aquaporin-4 Antibody-positive Definite Neuromyelitis Optica in a Patient With Thymectomy for Myasthenia Gravis

BACKGROUND:Since serum anti-aquaporin-4 (AQP4) antibody/neuromyelitis optica (NMO)-IgG has been detected as a specific biomarker for NMO), new diagnostic criteria have been proposed. Recently, a rare coexistence of NMO and myasthenia gravis (MG) has been documented. Here, we provide further evidence of the association of these 2 immunologic disorders and review the literature. CASE REPORT:A 60-year-old woman, who had a history of optic neuritis at age 43, developed longitudinally extended transverse myelitis (LETM). She had repeated optic neuritis and longitudinally extended transverse myelitis attacks, which have been treated by corticosteroid pulse therapy. She was diagnosed as having definite NMO, because serum anti-aquaporin-4 antibody was positive. She had also been suffering from generalized MG since age 30 and underwent thymectomy at age 40. There have been 14 patients with NMO associated with MG, most of whom developed NMO years after thymectomy. Our patient is the seventh patient with seropositive NMO who underwent thymectomy for MG. CONCLUSIONS:The coexistence of MG with thymectomy and seropositive NMO suggests an etiopathogenic link between these 2 disorders but remains underrecognized by neurologists. Neurologists should consider this possible association when encountering atypical presentations of either MG or NMO.