How is Devic's disease diagnosed? How does it differ from multiple sclerosis?
Testing for Devic's disease may include MRI (magnetic resonance imaging) scans to show inflammation of the spinal cord. MRI uses a large magnet, radio waves and a computer to produce images. In a person with Devic's disease, the MRI scan may show inflammation in a long segment of the spinal cord.
In MS, the findings tend to be in a short segment in the spinal cord. In Devic's disease, the MRI scan of the brain may be normal or show relatively mild changes. The optic nerve MRI may show areas of abnormality.
Another difference in findings for Devic's disease as compared to MS is that cerebrospinal fluid may show a greater increase in white blood cells than in MS patients, and may show a type of cell (neutrophil) that is not usually seen in MS.
In general, the test for oligoclonal bands (a test that is often positive in MS) is usually negative in the spinal fluid in Devic's disease. Oligoclonal bands are immunoglobulins (or antibodies), proteins produced by the immune system to fight off invaders like bacteria or viruses.
A blood test known as the NMO-IgG blood test is positive in 70 percent of patients diagnosed with Devic's disease. This test, in general, is negative in patients with multiple sclerosis. This has become an important marker for Devic's disease and has helped improve our understanding of this disorder.