Neuromyelitis optica spectrum disorder (NMOSD) is a rare disease that primarily affects the optic nerve and spinal cord. In rare circumstances, the disease can also affect the brainstem.
The disorder occurs when the immune system mistakenly attacks nerve cells and their support cells. Most patients with NMOSD have elevated levels of antibodies against either aquaporin-4 (AQP4) or myelin oligodendrocyte glycoprotein (MOG). AQP4 antibodies attach to the outside of the nervous system support cells called astrocytes and MOG antibodies attach to cells called oligodendrocytes. When the antibodies bind to the cells, they trigger the rest of the immune system to attack those cells and the nearby nerve cells and myelin, leading to inflammation and damage.
Most patients with NMOSD have relapsing and remitting forms of the disease where they experience flare-ups with periods of recovery in between. Symptoms tend to worsen with each reoccurrence, however, as more damage occurs each time.
Optic nerve symptoms
Optic neuritis, or the inflammation of the optic nerve, can lead to a number of problems with the visual system. The first symptom is usually pain inside the eye that can later progress to a loss of clear vision. The disease usually affects a single eye at a time but can sometimes affect both eyes. As it progresses, vision may become continually dimmer and blurrier, ultimately leading to blindness.
Spinal cord symptoms
Autoimmune attacks on the spinal cord can lead to a variety of different symptoms. Large sections of the spinal cord are usually attacked at once, a condition known as longitudinally extensive transverse myelitis.
The most common symptom for patients with spinal cord inflammation is pain in the form of uncomfortable burning or tingling (peripheral neuropathy) or as painful involuntary muscle contractions (muscle spasticity).
Patients may also experience weakness, trouble breathing, loss of sensation, and trouble controlling their bladder (urinary incontinence) and bowels (fecal incontinence). Joint reflexes may be diminished or exaggerated. Prolonged inflammation of the spine can lead to paralysis in serious cases.
Though much rarer than optic nerve or spinal cord symptoms, brain stem symptoms do sometimes occur. Damage to the brain stem can lead to double vision, uncoordinated walking, sleep attacks, slurred speech, and intractable (uncontrollable) vomiting or hiccups.
NMOSD may also lead to psychological complications including depression, and cognitive (thinking) problems. These issues may be due to inflammation in other parts of the brain. Alternatively, they could be a result of other symptoms, such as pain, leading to difficulty sleeping.
Last updated: Dec. 1, 2020
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