What is Devic's disease?
Devic's disease, also called neuromyelitis optica or NMO, is an immunological disorder that may be confused with multiple sclerosis (MS). Devic's disease is often characterized by immune attacks on the optic nerves (which transmit what you see to your brain) and the spinal cord. Patients may experience these attacks at the same time or at different times. They may also have just problems with the optic nerves alone or just problems with the spinal cord alone and still have Devic's disease.
Is Devic's disease a type of multiple sclerosis?
Until recently, Devic's disease was thought to be a kind of MS that caused more severe problems with the optic nerves and spinal cord. Recent research has suggested that Devic's disease is probably a different disease in which there is a specific immune attack on a molecule known as aquaporin 4. Our understanding of Devic's disease is changing quickly at the present time due to new research in this important disorder.
Symptoms and Causes
What are the symptoms of Devic's disease?
Potential symptoms of this disease include:
Diagnosis and Tests
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.
Management and Treatment
How is Devic's disease treated?
Since it is a relatively rare disease, there are no large-scale studies of treatment for Devic's disease. Treatment for an acute attack of Devic's usually begins with intravenous steroids followed by oral steroids. If the steroids are not effective, a treatment known as plasmapheresis is often used. This therapy cleans the antibodies from the blood by circulating it through a machine, similar to the way in which dialysis works.
Longer-term treatment medications may include:
- Immune-suppressing medicines such as azathioprine
- Chemotherapeutics such as mitoxantrone (Novantrone®)
- Other immune-suppressing medications have also been used (e.g., rituximab)
Devic's disease does not appear to respond to standard medications for multiple sclerosis. It is important therefore to identify this diagnosis so that more effective treatment for this problem can be used early in the disorder.