Neuromyelitis Optica - A Sister to Multiple Sclerosis
As MS patients we all know what a demyelinating disease is, right?
“...any disease of the nervous system in which the myeline sheath of neurons is damaged. This impairs the conduction of signals in the affected nerves, causing impairment in sensation, movement, cognition, or other functions depending on which nerves are involved.”
Demyelinating diseases of the central nervous system (CNS) include multiple sclerosis (MS), transverse myelitis (TM), Devic's disease (same as neuromyelitis optica), optic neuritis (ON), progressive multifocal leukoencephalopathy (PML), acute demyelinating encephalomyelitis (ADEM).
Neuromyelitis Optica (NMO), also known as Devic's Disease, is very rare. The exact figures are unknown but estimated to be no more than 6/1000 people (in Europe / North America), whereas with multiple sclerosis it is 1/800 people. Attacks of Devic's tend to be more severe with lasting disability, while initial attacks of RRMS recover almost fully and gradually move into a progressive stage.
Individuals with Devic’s disease often experience rapid visual loss, paralysis, and loss of leg, bladder, and bowel sensation. Some lose their sight permanently. These symptoms result from optic neuritis and transverse myelitis which are limited to eyes and spine, whereas MS can affect any part of the central nervous system.
The symptoms of Devic's are similar to multiple sclerosis and ADEM so tests are needed to exclude those possibilities. An MRI scan of the brain and spinal cord will be conducted, as well as lumbar puncture and visual evoked response test. Helpful in diagnosing the disease is the presence of a specific self-attacking immune protein an autoantibody referred to as NMO-IgG in the blood.
Dr. Vanda Lennon, research leader at the Mayo Clinic, has found that NMO-IgG initiates a chain of events which leads to a toxic build-up of the neurotransmitter glutamate. NMO-IgG binds to a protein that normally sops up excess glutamate from the space between brain cells. Too much glutamate can kill the cells that produce myelin, the protein that coats and protects neurons.
There are four aspects to treatment of neuromyelitis optica: Treating the acute attack, often with steroid medications; Preventing relapses using drugs to suppress the immune system; Treating residual symptoms from any relapse with appropriate medications and therapies; and Rehabilitation to help the person recover from an attack.