Neuromyelitis Optica Spectrum Disorder Developing after COVID-19 Vaccination Managed with Long-Term Eculizumab Treatment: A Case Report.

Introduction: Vaccine-associated neuromyelitis optica spectrum disorder (NMOSD) is rare, especially after COVID-19 vaccination. Furthermore, prior cases generally had specific symptoms. Case Presentation: We describe a patient who developed NMOSD following vaccination against COVID-19, whose initial symptoms were intractable hiccups and nausea. Thorough clinical examinations, including blood tests and imaging, immediately after symptom onset did not reveal any abnormal findings, and the anti-aquaporin-4 (AQP4) antibody titer was low. The patient's neurological symptoms (left side-dominant abnormal tingling sensation, touch allodynia, and muscle weakness) progressed. Approximately 5 months after symptom onset, a spinal cord lesion was found along the entire cervical cord that partially involved the thoracic cord. Owing to high anti-AQP4 antibody titers, the patient was diagnosed with AQP4-positive NMOSD. Despite steroid pulse therapy, the patient's neurological symptoms progressed daily, eventually resulting in quadriplegia. Concomitant plasmapheresis gradually improved the patient's muscle strength, and after 2 months of rehabilitation, the patient was discharged home. Before discharge, the patient started maintenance therapy with eculizumab and low-dose steroid therapy. Although she continues to experience some pain and numbness, she has not experienced any relapse for at least 2 years. Conclusion: Owing to the risk of severe disease, such as NMOSD, in patients who initially present with nonspecific neurological symptoms following vaccination, careful examination and monitoring are essential to ensure treatment can be started as soon as possible. Once diagnosed, eculizumab is an effective treatment for patients with AQP4-positive NMOSD following vaccination.