Spectrum Library

Dean M. Wingerchuk, MD, MSc, FRCP(C)

A Historical Perspective on NMO

Neuromyelitis optica (NMO), also known as Devic’s disease, was identified more than one hundred years ago as a severe disorder affecting the spinal cord (causing paralysis) and both optic nerves (causing blindness).Until recently, it was considered a rare and unusual form of multiple sclerosis (MS) because the affected spinal cord and optic nerve tissues showed lesions containing inflammation and demyelination similar to that seen in MS. Modern scientific and medical technology, including development of magnetic resonance imaging (MRI) and techniques to study the pathological changes in the nervous and immune systems, have led to the discovery that NMO is not only more severe than MS, but is probably a distinct disease. The most convincing evidence to support this argument is the recent discovery of a blood antibody called NMO-IgG, which is detected in NMO but not MS, and is now used to assist in diagnosis. This article will summarize the characteristics, diagnosis, and treatment of NMO.

Progress in understanding NMO began with careful study of the symptoms and signs experienced by patients with the disease and correlating those with the spinal cord and optic nerve abnormalities seen at autopsy. Affected individuals typically experienced an attack of optic neuritis which caused rapid visual loss (over hours to days) in one or both eyes, often with poor recovery of vision. At approximately the same time, they also had a myelitis attack, resulting in paraplegia, loss of sensation of the trunk and legs, and loss of bowel and bladder function. It was originally thought that the disease struck only once, leaving the affected person with severe disability, but reports accumulated throughout the 20th century showing that most patients experienced relapses of the disease. These recurrent attacks of optic neuritis and myelitis were not predictable, occurred months or years apart, and varied in severity and the amount of recovery of function after the attack ended. Examination of the optic nerves and spinal cord after death revealed multiple lesions containing inflammation and demyelination similar that seen in MS, though usually more severe and, importantly, the lesions did not extend to the brain itself. The pathological findings, however, were otherwise similar to MS….Cont……