TABLE 1.

Diagnostic Criteria for NMOSD

Core clinical characteristics

Optic neuritis Acute myelitis Area postrema syndrome: Episode of otherwise unexplained hiccups or nausea and vomiting Acute brainstem syndrome Symptomatic narcolepsy or acute diencephalic clinical syndrome with NMOSD-typical diencephalic MRI lesions Symptomatic cerebral syndrome with NMOSD-typical brain lesions

Diagnostic criteria for NMOSD AQP4-IgG–positive status

At least 1 core clinical characteristic Positive test for AQP4-IgG using best available detection method (cell-based assay recommended) Exclusion of alternate diagnoses

Diagnostic criteria for NMOSD AQP4-IgG–seronegative or unknown status

At least 2 core clinical characteristics occurring as a result of more than 1 clinical attack and meeting all of the following requirements: At least 1 core clinical characteristic must be optic neuritis, acute myelitis with LETM, or area postrema syndrome Dissemination in space (≥2 different core clinical characteristics) Fulfillment of additional MRI requirements, as applicable Negative tests for AQP4-IgG using best available detection method, or testing unavailable Exclusion of alternative diagnosis

Additional MRI requirements for NMOSD AQP4-IgG–seronegative and NMOSD with unknown AQP4-IgG status

Acute optic neuritis Acute myelitis Area postrema syndrome Acute brainstem syndrome

AQP4-IgG = aquaporin-4; LETM = longitudinally extensive transverse myelitis; MRI = magnetic resonance imaging; NMOSD = neuromyelitis optica spectrum disorder.