Neuromyelitis Optica Spectrum Disorder (NMOSD)

Neuromyelitis optica spectrum disorder (NMOSD) is a recently proposed unifying term for neuromyelitis optica (NMO) — also known as Devic's disease — and related syndromes. It is a relapsing inflammatory demyelinating disease that most commonly affects optic nerves and the spinal cord, leading to sudden vision loss or weakness in one or both eyes, and loss of sensation and bladder function.

The condition may also target other parts of the brain, especially the brainstem and hypothalamus, causing signs and symptoms such as severe and persistent vomiting and hiccups, or sleeping and eating disorders. Attacks of NMOSD tend to be more severe and often different in nature from those of the prototype form of multiple sclerosis (MS), another relapsing inflammatory disease of the optic nerves, spinal cord and brain; however, MS and NMOSD are often confused.

Mayo Clinic physicians and scientists introduced the term "neuromyelitis optica spectrum disorder" in 2007 to acknowledge that some patients with aquaporin-4 antibodies have recurrent transverse myelitis without optic neuritis and vice versa. The concept has gained international acceptance and has been broadened to be the unifying term for patients with a variety of clinical situations who are believed to have neuromyelitis optica or strongly related conditions.

In North America, NMOSD accounts for approximately 1 to 3 percent of cases of multiple sclerosis (MS)-like illness, although it accounts for 10 to 60 percent of such cases in Asia. In North America, although the majority of affected individuals are Caucasian, NMO disproportionately affects non-Caucasians.

Neuromyelitis optica is often misdiagnosed as MS, but it is important to accurately distinguish between these disorders, as several effective treatments for MS are ineffective or even harmful for NMO.

Mayo Clinic is recognized as a center of excellence for neuromyelitis optica diagnosis, treatment and research. The NMO study group encompasses neurologists and bench scientists at all three Mayo campuses with a focused commitment to discover the cause of this disease and develop new and better treatment strategies. Because of major advances in the understanding of the pathogenesis of NMO, more effective treatments may become available in the foreseeable future.

Discovery of the first antibody marker specific for NMO and its reporting in 2004 was a major breakthrough for Mayo's NMO study group. In just three years, this antibody test enabled accurate diagnosis and therapy of MS and related diseases nationally and internationally. A positive result for the NMO-IgG antibody allows early distinction of NMO from MS, and thus early initiation of NMO-appropriate treatment.

The close collaboration between all members of the NMO study group exemplifies Mayo's multidisciplinary team approach to clinical problems. Clinical outreach via antibody testing is performed in the Neuroimmunology Laboratory, investigated by Vanda A. Lennon, M.D., Ph.D., and Sean J. Pittock, M.D., on behalf of the Mayo Clinic Department of Laboratory Medicine and Pathology. This resource serves as a conduit for patient recruitment to clinical trials.

Neuropathological research on behalf of Claudia F. Lucchinetti, M.D., contributes further value to this outreach practice by providing unique insights into the immune mechanisms causing NMO through the analyses of tissues obtained from NMO patients. Dr. Lucchinetti also investigates tissues from animals with experimentally induced NMO in an effort to correlate clinical observations with a model system that is amenable to genetic and pharmacological manipulation.

Likewise, Charles L. Howe, Ph.D., is developing in vitro cell-based models of the neuroimmune interface that will permit mechanistic investigations of NMO immunopathology at the cellular and molecular level. Additionally, two of the NMO study group's clinical neurologists, Dean M. Wingerchuk, M.D., and Brian G. Weinshenker, M.D., are world-renowned for their expertise in the design of clinical trials, epidemiology and genetics of NMO.

All members of Mayo's NMO study group have exceptional expertise in the accurate diagnosis and optimal management of patients with NMO. Recently, Drs. Pittock and Wingerchuk completed a pilot study of eculizumab that was very promising and resulted in launching a definitive worldwide phase III clinical trial. The outcome of this trial will hopefully result in registration of this drug for NMO treatment.

The complementary talents and subspecialty interests of this coalition of Mayo clinicians and scientists reflects a long history of working together on projects related to neuromyelitis optica and multiple sclerosis and identifying the most optimal treatments.