Efficacy of Ravulizumab During the Acute Phase of Neuromyelitis Optica Spectrum Disorder.

Background: Ravulizumab is effective in preventing relapse of neuromyelitis optica spectrum disorder (NMOSD). However, its efficacy during the acute phase of NMOSD has rarely been reported. Case: We report the case of a 66-year-old woman with anti-aquaporin-4 antibody-positive NMOSD. Six years ago, the patient had impaired vision and visual field loss in her right eye and received steroid therapy at another hospital for 6 months, after which no further treatment was given. On admission, she presented with weakness in both lower limbs, numbness from the chest to the lower body, and impaired bladder sensation. Neurological examination revealed bilateral lower limb weakness and hypoesthesia below the 4th thoracic spinal segment. The Expanded Disability Status Scale (EDSS) score was 3.5. Cerebrospinal fluid examination revealed mild cytosis, elevated protein levels, an elevated immunoglobulin G index, and positive oligoclonal bands. Magnetic resonance imaging revealed longitudinally extensive transverse myelitis from the 2nd to 8th thoracic vertebral levels. She was diagnosed with a relapse of NMOSD. After one course of steroid pulse therapy, she developed complete paraplegia in both legs. The EDSS score was 8.5. Immunoadsorption therapy, prednisolone, and azathioprine were initiated; however, these treatments were ineffective. Ravulizumab was administered immediately after immunoadsorption therapies. Treatment with prednisolone, azathioprine, and ravulizumab was continued. Her symptoms gradually improved, and prednisolone was gradually tapered and discontinued. She could walk independently after 6 months. The EDSS score was 3.5 at the time of discharge. Conclusion: Ravulizumab may be a viable treatment option when administered during the acute phase of NMOSD.