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Neuromyelitis optica is a nervous system disorder that can impair vision and lead to weakness or paralysis in the arms and legs. People who have the disorder typically experience sporadic episodes of optic nerve and spinal cord inflammation between symptom-free periods. The symptoms of neuromyelitis optica are similar to those associated with multiple sclerosis, though the two conditions can be distinguished by the severity of episodes and the amount of brain involvement. There is no cure, but doctors can prescribe medications that lessen the frequency and length of attacks.
Doctors do not fully understand the causes of neuromyelitis optica, but it is believed that genetics plays the most important role in its development. It is an autoimmune disorder in which the immune system attacks the fatty linings of nerve cells called myelin. As the protective myelin coverings become inflamed and deteriorated, nerve cells lose their ability to generate and send impulses in an efficient manner.
When the optic nerve is impaired by neuromyelitis optica, a person may experience eye pain, blurry vision, and an inability to differentiate colors. Vision problems tend to develop suddenly at the beginning of an episode and gradually worsen over the course of many days. Temporary blindness can occur after about two or three weeks during a severe episode. Weakness, numbness, and tingling sensations in the extremities are also common with neuromyelitis optica, and some people experience temporary paralysis. Symptomatic episodes may return every few days or weeks, but many people enjoy months or even years between attacks.
When a patient shows signs of neuromyelitis optica, specialists can perform a series of diagnostic tests to confirm the condition and rule out multiple sclerosis. Neurological exams, computerized tomography scans, and magnetic resonance imaging screens are used to identify myelin breakdown along the optic nerve and spinal cord and to make sure brain cells are not inflamed. Patients who seek consultations during symptom-free periods may show very few signs of a chronic disorder, so they may be asked to return when episodes arise.
After confirming a diagnosis, a doctor can provide corticosteroids, such as prednisone, to relieve immediate symptoms of pain and inflammation. In order to reduce the chances of frequent future episodes, a patient may be prescribed immunosuppressive drugs to take daily. Most people who take their medications still have occasional attacks, but they tend to be less severe. If serious problems continue to recur, a patient may need to receive regular blood plasma transfusions to dilute the autoimmune response.