This study aims to determine which method is more suitable for clinical application by comparing the sensitivity, specificity, and accuracy of serum AQP4-IgG detection using live cell CBA and fixed cell CBA methods, thereby improving the diagnostic accuracy of neuromyelitis optica spectrum disorders (NMOSD).

This is a multi-center comparative real-world study on AQP4 Antibody Detection Methods Using Live Cell and Fixed Cell-Based Assay Technologies. This study aims to determine which method is more suitable for clinical application by comparing the sensitivity, specificity, and accuracy of serum AQP4-IgG detection using live cell CBA and fixed cell CBA methods, thereby improving the diagnostic accuracy of neuromyelitis optica spectrum disorders (NMOSD). One hundred and twenty patients from 3 centres in China will be enrolled.

Inclusion Criteria:

• NMOSD: Confirm a diagnosis of NMOSD according to 2015 NMOSD diagnostic criteria by IPND (International Panel for NMO Diagnosis) suspected NMOSD: cases having features suggestive of NMOSD but can not confirm a diagnosis of NMOSD according to 2015 NMOSD diagnostic criteria by IPND (International Panel for NMO Diagnosis).

the following 'high risk' clinical and laboratory features had to be met

1. optic neuritis that was either severe with poor recovery (residual visual acuity in better eye worse or equal to 6/36), bilateral (simultaneous orsequential within 3 months) or recurrent (more than 2 attacks) as the sole clinical manifestation of demyelinating disease,
2. severe transverse myelitis with a central cord syndrome (symmetrical, motor, sensory and bladder involvement) and poor recovery (residual EDSS greater than 5.0) or a longitudinally extensive lesion of the spinal cord spanning 3 or more vertebral segments on magnetic resonance imaging (MRI) or
3. demyelinating disease clinically confined to the optic nerve and spinal cord with at least one of the following: normal or atypical MRI of the brain (fewer than 2 periventricular lesions), negative oligoclonal bands in cerebrospinal fluid, raised CSF protein or a CSF pleocytosis (more than 10 cells per μl) 2.All subjects provided written informed consent.

Exclusion Criteria:

• 1.Patients with incomplete clinical information. 2.Patients without serum samples.

Sex, Gender, diagnose, the number of relapses in NMOSD patients