Neuromyelitis Optica and Multiple Sclerosis
When clinicians are considering a diagnosis of multiple sclerosis, one of the other diseases that may be on their radar is neuromyelitis optica. That’s because neuromyelitis optica and multiple sclerosis share some critical characteristics.
Neuromyelitis optica (NMO) is about one hundred times less common than multiple sclerosis, with an estimated 4,000 individuals having the diagnosis in the United States, according to the National Multiple Sclerosis Society, compared with more than 400,000 cases of multiple sclerosis. In both disorders, damage occurs to the myelin cells:
- In NMO, the optic nerve cells and spinal cord cells are typically the only ones affected during the early stages of the disease. However, lesions may be seen in some areas of the brain. Symptoms of neuromyelitis optica include rapid onset of eye pain, loss of vision, lack of sensation, bowel and bladder problems, and weakness or paralysis of the arms or legs.
- In multiple sclerosis, lesions typically affect the brain, spinal cord, and optic nerve.
- In neuromyelitis optica, the body usually develops antibodies (NMO-IgG) to attack the aquaporin 4 antigen. These antibodies often, but not always, can be detected in the blood of individuals with the disorder. That is, you could have a false negative NMO-IgG test result.
- In multiple sclerosis, no specific antigen has been found, although countless studies have been performed in attempts to definitively identify them.
- People with neuromyelitis optica tend to have severe acute episodes early in the disease process while those with multiple sclerosis generally have milder events that can grow worse over time
- The presence of several conditions simultaneously is not uncommon in both neuromyelitis optica and multiple sclerosis. Some of those conditions include Sjogren’s syndrome, Leber’s hereditary optic neuropathy, transverse myelitis, and systemic lupus erythematosus.
New developments for neuromyelitis optica
The authors of a newly published study on neuromyelitis optica report that several biomarkers can make it easier for clinicians to identify the severity of relapses of the disease as well as help with diagnosis and evaluation. Those biomarkers include interleukin-6 in the peripheral blood and glial fibrillary acidic protein in the cerebrospinal fluid.
Currently there are no Food and Drug Administration (FDA) approved drugs treatments for neuromyelitis optica. However, a variety of drugs are used in the United States to manage symptoms and reduce relapses, such as methylprednisolone, mycophenolate mofetil, azathioprine, and ritixumab. The effectiveness of this latter drug was recently reported in two studies.
Six patients were treated with 1,000 mg rituximab two days per month, and the infusions were repeated every 6 to 8 months. Four of the patients remained free of relapse during treatment and their Expanded Disability Status Scale scores did not worsen while they were being treated. One patient did not improve and the other could not be evaluated.
Yet another new study looked at the effectiveness of ritixumab in four patients with severe relapsing neuromyelitis optica. The drug stabilized all four individuals, and after they discontinued treatment, they experienced prolonged remission that ranged from 4.5 to 10.5 years, including 3 to 9 years when they participated in no therapies at all.
The possibility that Epstein-Barr virus may have a role in neuromyelitis optica was explored in other new research. Some experts also believe the virus may be a key player in the development of multiple sclerosis.
The investigators measured the levels of antibodies against Epstein-Barr virus antigens in 50 individuals with neuromyelitis optica, 51 patients with multiple sclerosis, and 52 healthy volunteers. In addition, cerebrospinal fluid antibodies were checked in 37 patients with NMO and 33 with MS.
Individuals with neuromyelitis optica were twice as likely to have anti-Epstein-Barr IgG antibodies than healthy volunteers or patients with multiple sclerosis. Patients with NMO also had significantly higher antibody titres (concentrations) and cerebrospinal fluid antibody titres than individuals in the other two groups. These findings indicate that active Epstein-Barr virus replication occurs in people with NMO.
Neuromyelitis optica is similar to multiple sclerosis and one of several conditions that should be considered during the diagnostic process. Because acute episodes are usually severe and can cause irreversible damage, early diagnosis and treatment are critical.
Chang KH et al. Biomarkers for neuromyelitis optica. Clinica Chimica Acta 2014 Nov 7; 440C:64-71
Fernandez-Megia MJ et al. Clinical evaluation of rituximab treatment for neuromyelitis optica. Neurologia 2014 Nov 11
Masuda S et al. Epstein-Barr virus persistence and reactivation in neuromyelitis optica. Journal of Neurology, Neurosurgery and Psychiatry 2014 Nov 18
Weinfurtner K et al. Prolonged remission in neuromyelitis optica following cessation of rituximab treatment. Journal of Child Neurology 2014 Nov 10