What is Neuromyelitis Optics vs. Multiple Sclerosis

by Dr. James W. Stark

Neuromyelitis optics (NMO), also known as Devic’s Disease, is an autoimmune, demyelinating disorder just like Multiple Sclerosis (MS). However, while the demyelination in MS is found throughout the brain and spinal cord, the demyelination in NMO is almost exclusively restricted to the optic nerves and the spinal cord. NMO was long thought to be a subset of MS until, in 2004, Dr. Vanda Lennon and her colleagues discovered that the cause of the inflammation in NMO is the immune system attacking a specific water-transport channel that is only found in the optic nerves and the spinal cord. While we still do not know why this occurs, we do know how; the immune attack is carried out by anti-aquaporin4 antibodies and a test for that antibody is readily available at commercial labs. This simple blood test helps diagnose NMO (although some patients with NMO do not test positive for anti-aquaporin4 antibodies.) In multiple sclerosis, we know the immune system also causes damage to myelin, but we still do not fully understand the mechanism of how the inflammation occurs. This is also partly why there is no one simple test for the diagnosis of MS. In the past, neurologists have treated NMO with various chemotherapies as well as some of the MS medications, however, in the last few years, three new medications have been FDA-approved specifically to treat NMO. These include Soliris (eclizumab), Uplizna (inebilizumab), and Enspryng (satralizumab-mwge) and, although NMO remains a serious, life-long condition, these medications have greatly improved patient outcomes in this disease.