Neuromyelitis Optica

The signs and symptoms of neuromyelitis optica include optic neuritis, which presents with acute onset vision loss in one eye and pain with eye movements. The vision loss can either occur in the central or peripheral aspects of the visual field. There may also be a relative afferent pupillary defect in the affected eye, which is a clinical sign indicative of optic nerve dysfunction. It occurs when the affected pupil dilates inappropriately in response to light. Optic neuritis can also affect color vision, with colors appearing less vivid than usual, and some may experience scotomas, an alteration in the visual field that looks like blind spots, or flashing and flickering lights.  

Another symptom of NMO is transverse myelitis (e.g., inflammation of the spinal cord), which can lead to pain, weakness, and paralysis of the upper and lower extremities, as well as abnormal sensation (i.e., loss of sensation, paresthesias) in the affected limbs. Some may also experience loss of bowel and bladder function. Those with NMO can suffer from intractable hiccups and unexplained nausea and vomiting, which is related to lesions in the area postrema. Narcolepsy (i.e., uncontrolled daytime sleepiness) can also be a symptom of NMO, due to lesions affecting regions of the brain involved in sleep regulation such as the hypothalamus.  

Most individuals with NMO have relapsing attacks, followed by partial recovery during periods of remission. The attacks can be spread days, months, or even years apart. More rarely, the condition can be monophasic and the individual may only experience the symptoms once in their life. The prognosis of NMO depends on whether the individual has relapsing symptoms. Approximately half of those with relapsing disease have resulting paralysis in one or more of their limbs compared to only a third of those with monophasic disease. Additionally, approximately 60% of those with relapsing disease are permanently blind in one or both eyes, compared to 22% of those with monophasic disease.  

There is currently no cure for neuromyelitis optica, however, there are treatment modalities that focus on symptom management and prevention of relapse. Rehabilitation, including physical therapy and occupational therapy, can help maintain function and mobility. Preventative treatments for NMO include immunosuppressive drugs such as rituximab, azathioprine, mycophenolate mofetil, and methotrexate which modulate the immune system’s response to prevent future attacks. The U.S. Food and Drug Administration (FDA) has approved three monoclonal antibody treatments for NMO: eculizumab, inebilizumab-cdon, and satralizumab-mwge, which can also reduce the risk of relapses in adults who are anti-aquaporin-4 antibody positive.  

Acute attacks of neuromyelitis optica can be treated with high-dose corticosteroids (e.g., methylprednisolone) that are typically administered intravenously for 5 to 10 days. Intravenous immunoglobulin (IVIG) can also be administered. In more severe cases, plasma exchange therapy, a process where harmful antibodies are removed from the blood and normal plasma is then replenished, may also be utilized. The management of NMO is a long-term process, requiring a team of healthcare professionals, including neurologists, ophthalmologists, and rehabilitation specialists.