Novel advances in the diagnosis and treatment of neuromyelitis optica: is there a need to redefine the gold standard?

Abstract

Neuromyelitis optica (NMO) is an inflammatory disease of the central nervous system characterized by severe attacks of optic neuritis and myelitis and, unlike multiple sclerosis, was initially thought to spare the brain in the early stages. The term NMO spectrum disorder (NMOSD) was recently used to qualify restricted forms of the disorder, which include recurrent optic neuritis, relapsing transverse myelitis and some encephalitic/brainstem presentations associated with positive aquaporin4 antibodies. It was also recently found that other immunological targets such as myelin oligodendrocyte glycoprotein (MOG) may be associated with seronegative NMO patients. In the present study, we detail the moving concept of NMOSD from the recent years and propose some therapeutic strategies that are clearly different compared with multiple sclerosis treatment.

Keywords::

• aquaporin4
• antibodies
• multiple sclerosis
• neuromyelitis optica
• neuromyelitis optica spectrum disorder
• treatment

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • Neuromyelitis optica (NMO) has recently been demonstrated as a separate disease from multiple sclerosis that is clearly largely mediated by B-cells and especially by AQP-4 antibodies.

• • AQP4 is the first antigenic target that has been discovered for an inflammatory central nervous system disease.

• • AQP4 antibodies have a sensistivity of 70–80% and a high specificity (around 100%) that allow to define a new group of patients as having NMO spectrum disorders (NMOSD). NMOSD patients did not encompass strict NMO criteria but it has beenclearly demonstrated that these patients are at a high risk of conversion to classical NMO after several months or years.

• • Encephalic symptoms may occurred in NMO and NMOSD patients and their occurrence should not rule out the diagnosis.

• • NMO is frequently associated to other autoimmune diseases but this occurrence is due to an overlapping condition and therapeutical strategies should not be modified in case of such associations. The recent progress of pathophysiological knowledge in NMO (AQP4 discovery, importance of IL-6 and IL-17, role of the complement) should give us new opportunities for treating patients with the best efficacy.

Notes

Data taken from [10].