Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory, demyelinating disease in 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 optical neuritis or myelitis in patients with antibodies against AQP4. Previously classified as a variant of Multiple Sclerosis (MS), NMOSD is now recognized as a distinct entity.