[Neuromyelitis optica spectrum disorder with positive aquaporin-4 antibodies and anti-myelin oligodendrocyte glycoprotein antibodies].

Neuromyelitis optica is a rare inflammatory demyelinating disorder of the central nervous system, most often associated with aquaporin-4 (AQP4) antibodies and, less frequently, with myelin oligodendrocyte glycoprotein (MOG) antibodies. AQP4-positive disease is considered an autoimmune astrocytopathy, whereas MOG-positive disease represents an oligodendrocytopathy. Although these entities have distinct pathophysiological mechanisms, rare cases of double AQP4/MOG positivity have been reported, raising specific diagnostic, prognostic, and therapeutic issues. We report the case of a 48-year-old woman admitted with severe left optic neuritis and contralateral hypesthesia. Orbital MRI revealed anterior involvement of the left optic nerve with perineuritis along with bilateral chiasmal lesions. Spinal MRI demonstrated a focal cervical lesion consistent with transverse myelitis. Both AQP4 and MOG antibodies were positive in the serum and cerebrospinal fluid. Plasma exchange combined with intravenous corticosteroids led to partial improvement, but the patient experienced an early relapse on oral steroids, resulting in severe visual loss despite initiation of rituximab. Double-positive cases remain rare and clinically heterogeneous. Our observation is notable for the simultaneous occurrence of anterior, chiasmal, and spinal cord lesions at the onset of the disease. The concordance between serological profiles and MRI features typical of each entity supports the concept of dual pathogenicity. This case underlines the importance of systematic testing for both AQP4 and MOG antibodies in severe, bilateral, or atypical optic neuritis and supports the need for early immunosuppressive treatment to limit visual sequelae.