Neuromyelitis optica, also known as Devic's disease or NMO, is a rare central nervous system condition that causes swelling and inflammation of the eye nerves and the spinal cord; the former is labeled optic neuritis, and the latter myelitis. This disorder takes place when the immune system of the body attacks its own cells in the central nervous system, in particular the optic nerves and spinal cord, but also the brain. Though no cause has been established, it has been observed that NMO may appear following an infection. It may also be related to another autoimmune disease. Vomiting may precede an NMO attack, and it may manifest in children in the form of confusion seizures, or coma. An NMO attack may be reversed, but if it’s too severe it can lead to permanent loss of vision and walking difficulties.
The symptoms of NMO are usually associated with optic nerve and spinal cord dysfunction, and include loss or blurring of vision in one or both eyes, loss of color vision, paralysis (no motor function) of a limb or limbs, paraparesis (weakness) of a limb or limbs, loss of sensation, loss of bladder or bowel control, profound bladder retention, intractable nausea and vomiting, and intractable hiccups. Neuromyelitis optica is an uncommon disease, but among those who do develop it, it is more prevalent in people of African descent, especially women, in whom the relapsing form of the disease is more frequent (70% of people with NMO experience relapses after the original onset of symptoms). Speaking of onset, the average age is 40, although it can occur between the ages of 3 and 90 as well.
The two main acute treatments for NMO are intravenous steroids and plasma exchange (Plex). High intravenous dosages of methyl-prednisolone during a 5-day course is the customary treatment for suspected cases of acute myelitis, except in instances where there are strong reasons against it. The continuation or stoppage of intravenous steroid treatment depends on clinical course and MRI appearance after the 5 days. Plex is indicated for mild to aggressive cases of transverse myelitis and optic neuritis where intravenous steroids have not improved the condition. Plex yields better results if started early, preferably before the course of steroids has finished, and within the acute or sub-acute stage of myelitis.
If neither steroids nor Plex are effective in reducing spinal cord inflammation, there are alternative treatments such as immunosuppressants or immunomodulatory agents, including the intravenous chemotherapy drug cyclophosphamide. In that case, an oncology team needs to be present when administering the drug and to anticipate a potential adverse reaction to aggressive immunosupression.
Since NMO is a recurrent and crushing disease, long-term management is something that must be strongly considered. Approximately 50% of diagnosed and untreated NMO patients are wheelchair-bound and functionally blind by 5 years. Early therapy and rehab are instrumental in lessening the impact of NMO-related complications like depression, spasticity, bowel and bladder problems, fatigue, and neuropathic pain. Long-term management also involves ongoing immunosuppressant treatment. Unfortunately, this is done with off label medications that have not been approved by the FDA , mainly mycophenolate mofetil, rituximab, and azathioprine. Moreover, these drugs render patients prone to upper respiratory and urinary tract infections, among others.
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, which can in turn aid in finding new and better ways to treat and prevent NMO.
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