2015 Criteria (Neuromyelitis Optica Spectrum)

What the result means

With AQP4-IgG

One core clinical characteristic, a positive test by the best available method, and exclusion of alternative diagnoses.

Without AQP4-IgG

TWO different core characteristics; at least one of them optic neuritis, myelitis with a longitudinally extensive lesion, or area postrema syndrome; the MRI requirement met for each; and exclusion.

Unknown counts as negative

An untested or pending AQP4-IgG follows the seronegative rule, not the seropositive one.

Six core characteristics

Optic neuritis; acute myelitis; area postrema syndrome; acute brainstem syndrome; narcolepsy or acute diencephalic syndrome with typical lesions; cerebral syndrome with typical lesions.

The asymmetry

One episode of longitudinally extensive myelitis is enough seropositive and NOT enough seronegative. Applying one rule to both diagnoses on evidence the panel judged insufficient.

Why it cuts both ways

Several multiple sclerosis disease-modifying therapies make NMOSD worse, so both over- and under-diagnosis carry harm.

MRI, myelitis

An intramedullary lesion over 3 or more contiguous segments, or 3 or more contiguous segments of focal cord atrophy.