Understanding NMOSD & MOGAD

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory, demyelinating disease of the central nervous system. The main characteristics of NMOSD are recurrent episodes of optic neuritis or acute myelitis.

The area postrema syndrome, characterized by episodes of intractable hiccups and problems with nausea and vomiting, frequently precedes the onset of optic neuritis or myelitis in patients with antibodies against aquaporin-4 (AQP4).

NMOSD as a Distinct Disease Entity

Previously classified as a variant of multiple sclerosis (MS), NMOSD is now recognized as a distinct clinical and pathological entity.

Role of AQP4 and MOG Antibodies

Most patients suffering from NMOSD test positive for AQP4 antibodies, but a subset instead has myelin oligodendrocyte glycoprotein (MOG) antibodies and is diagnosed with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). While NMOSD and MOGAD share clinical characteristics, their pathogenesis and disease courses often differ significantly.

Importance of Accurate Diagnosis and Antibody Testing

Accurate differential diagnosis from MS is crucial, since both NMOSD and MOGAD require different treatment approaches. For patients presenting with any of these symptoms, it is recommended that serologic workups include both MOG and AQP4 antibody testing using cell-based assays (CBA). In rare cases, both AQP4 and MOG antibodies can be detected, but whether these cases represent a specific phenotype remains unknown.