Severe Monocular Vision Loss Followed by Gait Difficulty

A 56-year-old woman sought care for painless vision loss over 24 hours in the superior field of her right eye, which progressed to total vision loss. Intravenous corticosteroids were administered over 5 days, and she recovered well. Approximately 6 months later, paresthesias and sensory loss of her legs developed, which was sufficiently severe that she was unable to walk. She had severe impairment of vibration sense and lesser impairment of position sense, as well as proximal weakness of both legs. She recovered but had persistent burning dysesthesias of the legs. Magnetic resonance imaging of the orbits at the onset of symptoms showed gadolinium enhancement extending from the middle of the orbit posteriorly, almost to the level of the optic chiasm. Magnetic resonance imaging of the spine at the time of acute myelitis revealed a long spinal cord lesion extending from the lower cervical cord to the conus which was central and homogeneous on T2 images and exhibited patchy gadolinium enhancement. Cerebrospinal fluid analysis showed 37 leukocytes/µL with lymphocyte predominance and negative tests for oligoclonal bands. On serologic analysis, she was positive for aquaporin-4-immunoglobulin G antibodies by enzyme-linked immunosorbent assay. The patient was diagnosed with neuromyelitis optica spectrum disorder, aquaporin-4-immunoglobulin G seropositive. The patient was started on rituximab treatment. After 2 years, she decided to discontinue treatment because she was concerned about potential adverse effects. Six months after discontinuing rituximab, severe weakness of her right leg developed, which improved with intravenous corticosteroids. Rituximab therapy was restarted, 2 doses of 1 g each, but she had 1 further episode of myelitis 2 weeks after receiving rituximab. Six months later, her visual acuity in the right eye was only counting fingers, and she had a flaccid paraplegia with areflexia of the lower extremities and total loss of sensory function below T4.