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A patient getting treatment at the Mass General infusion center

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disease of the central nervous system in which a person’s immune system invades the optic nerves and spinal cord leading to vision loss and paralysis. NMOSD was long considered a version of multiple sclerosis (MS), but in 2004, doctors discovered an antibody (a protein in the blood) that helped create a discrete diagnosis. Unlike in MS, the disease does not progress between attacks, but the attacks themselves are generally more severe than in those patients with MS. Generally characterized by an unpredictable and relapsing course, NMO causes increasing disability with each attack. Though most patients partially recover function between attacks, some patients will suffer permanent vision loss and/or diverse neurological symptoms; a few, even death.

In 1894, Eugene Devic first characterized a disorder among his patients that included optic neuritis and myelitis. For years, NMO was called Devic’s Disease, but that name has fallen into disuse, as Neuromyelitis optica (NMO) and Neuromyelitis optica spectrum disorder (NMOSD) have become the more common monikers. The words “spectrum disorder” were added to the formal name of the disease in 2015 when physicians researching NMO defined a continuum of symptoms that can constitute a broad range of manifestations.

NMOSD strikes more females than males. The prevalence of the disease ranges from 0.5 – 10 per 100,000. Africans, East Asians and Latin Americans tend to have a higher prevalence of NMOSD than Caucasian populations in Europe and the United States.

When NMOSD attacks, patients may experience optic neuritis – inflammation of the optic nerves that causes eye pain and reduced vision in one or both eyes and/or transverse myelitis – inflammation of a segment of the spinal cord, causing sensory changes, potential loss of bladder and bowel control, numbness, tingling and possible paralysis. Attacks of the brainstem can lead to hiccupping, nausea and/or vomiting. Corticosteroids and plasmapheresis (removing and replacing components of a patient’s blood) are effective in stopping NMO relapses. Many experience unusual fatigue that can persist long after the treatment and healing period.

After treatment for acute attacks, the disease exists in a sort of remission state. At these times, there is no active disease progression, but patients continue to suffer from symptoms due to previous damage in the nervous system. In order to prevent additional injury from future attacks, it is imperative that people with NMOSD take medication regularly. NMOSD never goes away on its own, so preventive treatment is required lifelong. There are a number of medications that successfully suppress the immune system in NMOSD patients, though in June of 2019, the FDA first approved a drug for NMOSD.

The majority of people with NMO have an antibody that mistakenly attacks a particular protein in the central nervous system (CNS), the Aquaporin 4 (AQP4) water channel, the most abundant water channel protein in the CNS. Others suffering with radiological and clinical criteria consistent with NMO may have either no currently-identified antibody, or may test positive for a recently-discovered antibody, MOG (myelin oligodendrocyte glycoprotein).

Though there is no cure for NMOSD at this time, we are encouraged that the last fifteen years have brought an abundance of interest and a number of positive therapies and even a first FDA-approved drug for NMOSD. There are additional drugs already on the horizon, and we are proud to participate in a number of studies and trials to improve treatments and one day, we hope, to find a cure.