This is an observational cohort study based on data from the hospital-based NMOSD registry (Chinese Medical Research Registration Number MR-31-22-008563; ChiCTR2000030651). Between October 2023 (when eculizumab was approved for NMOSD in China) and February 2025, 26 consecutive patients with AQP4-IgG-positive NMOSD received eculizumab, and 9 of them were included in this study.

Inclusion Criteria:

(1)Patients have been diagnosed with NMOSD and tested seropositive for AQP4 antibody; (2) Age ≥ 18 years; (3) Received eculizumab during an acute phase of NMOSD, defined as within 30 days of attack onset； (4) Adherence to an 8-week follow-up from eculizumab initiation.

Exclusion Criteria:

1. Patients with unresolved Neisseria meningitidis infection or severe infections that preclude the use of immunotherapy;
2. Patients with severe comorbidities (such as heart failure, respiratory failure, severe hepatic or renal dysfunction, etc.);
3. Patients with incomplete records of clinical symptoms and signs, as well as insufficient data on serum marker tests in their medical records.

This is an observational cohort study based on data from the prospectively followed NMOSD cohort of the hospital-based registry (The Chinese Medical Research Registration Number MR-31-22-008563; ChiCTR2000030651). Between October 2023 (when eculizumab was approved for NMOSD in China) and February 2025 consecutive patients with AQP4-IgG-positive NMOSD received eculizumab were enrolled.