S1P, sphingosine 1-phosphate.
| AQP4-IgG testing | AQP4-IgG seropositive | Seronegative or unknown |
|---|---|---|
| Signs and symptoms | ≥1 of 6 core characteristics | ≥2 of 6 characteristics, with ≥1 of 3 hallmark symptoms Additional MRI requirements |
| Exclusions | Exclude alternative diagnoses (eg, MS, cancer, HIV) |
|
| Hallmark symptoms | Other potential symptoms |
|---|---|
| Optic neuritis | Acute brain stem syndrome |
| Acute myelitis | Symptomatic narcolepsy or acute diencephalic clinical syndrome with NMOSD-typical diencephalic MRI lesions |
| Area postrema syndrome | Symptomatic cerebral syndrome with NMOSD- typical brain lesions |
| MRI Requirements |
|---|
| Acute optic neuritis: requires brain MRI showing (a) normal findings or only nonspecific white matter lesions OR (b) optic nerve MRI with T2-hyperintense lesion or T1-weighted Gd-enhancing lesion extending >1/2 optic nerve length or involving optic chiasm |
| Acute myelitis: requires associated intramedullary MRI lesion extending ≥3 contiguous segments (LETM) OR ≥3 contiguous segments of focal spinal cord atrophy in patients with history compatible with acute myelitis |
| Area postrema syndrome: requires associated dorsal medulla/area postrema lesions |
| Acute brain stem syndrome: requires associated periependymal brain stem lesions. |
S1P, sphingosine 1-phosphate.