Abstract
Introduction. According to the 2015 diagnostic criteria for neuromyelitis optica spectrum disorders (NMOSD), in aquaporin-4 immunoglobulin G (AQP4-IgG) seronegative patients, NMOSD can be diagnosed if stringent clinical and magnetic resonance imaging (MRI) criteria are fulfilled; however, in these cases, diagnostic and therapeutic challenges could arise. Case Description. A young man presented a severe, bilateral optic neuritis and paraparesis in an acute phase. MRI evidenced 3 spinal cord T1-contrast-enhanced (T1-Gd+) myelitic lesions, extending <3 vertebral segments. AQP4-IgG and oligoclonal bands were negative. Following a relapse, MRI showed 2 T1-Gd+ spinal cord lesions, extending <3 vertebral segments, and a T1-Gd+ lesion in both optic nerves, near their confluence in the chiasm. After administering rituximab, there were no new relapses, with the consequent improvement of the clinical and MRI lesions. Conclusion. The concurrent display of bilateral optic neuritis and short myelitis constitutes a “borderline” case. Rituximab may represent the most appropriate therapeutic choice possible cases of NMOSD.