Understanding Devic’s Disease
Devic’s disease (also known as Neuromyelitis optica or NMO) is a rare disorder similar to multiple sclerosis (MS). It is an inflammatory disease of the central nervous system that causes episodes of inflammation and damage to the myelin, the fatty, protective covering of the nerves, in the eye and the spinal chord. It may cause temporary or permanent blindness, in one or both eyes, varying degrees of weakness or paralysis in the legs and arms, painful spasms, loss of sensation, and bladder or bowel dysfunction. Devic’s disease is most common in women. The onset varies from childhood to adulthood.
The main symptoms of Devic’s disease are a rapid, intense decrease in vision in either or both eyes, diminished light sensitivity, loss of color vision, loss of sensation, numbness, loss of bladder control, lack of coordination, and muscle weakness.
The outcome of this disease is highly variable, depending on whether there is a tendency for relapses to occur after the initial symptoms. The major risk to patients is severe damage to the upper spinal cord, which can lead to the inability to breathe on one’s own. Some patients seem to enter a long period of time where the disease remains stable.
Diagnosis of Devic’s disease requires several steps. First, a neurological examination is needed to examine parts of the nervous system such as muscle strength, reflexes, coordination and balance, sensation, vision and speech. Then, a 45 minute Magnetic Resonance Image (MRI) scan is done in order to examine the neck, spinal cord, soft tissues and brain. Evoked potentials, to test and record the brain’s responses to sound, touch and light are then performed using a gel to position small disks on the scalp and in some cases, the earlobes, neck, shoulders and back. This testing is harmless, painless and very sensitive in detecting damaged areas in the brain. In some cases, a spinal tap is necessary. In this procedure, a physician uses a thin, hollow needle to remove small samples of fluid from within the spinal canal.
Short-term treatment of Devic’s disease includes medication to manage acute attacks and prevent future ones. Currently, there have not been any controlled clinical trials that have proven effectiveness of any long-term treatment. However, plasma exchange may be a long-term option. Plasma exchange is a procedure that involves removing some blood and mechanically separating the blood cells from the fluid. Blood cells then are mixed with a replacement solution, such as albumin or a synthetic fluid with properties like plasma. The solution with the blood is then returned to the body. This works in approximately 40 percent of patients.
