Importance of Establishing National Multicenter Consortium for Neuromyelitis Optica Spectrum Disorders
Abstract & Commentary
Synopsis: Based on a retrospective analysis of 187 patients with neuromyelitis optica (NMO) or an NMO spectrum disorder from three medical centers, the authors report their initial findings on the epidemiology of NMO/NMO spectrum disorders.
Source: Mealy MA, et al. Epidemiology of neuromyelitis optica in the United States. Arch Neurol .doi:10.1001/archneurol.2012.314.
Neuromyelitis optica (NMO) is an inflammatory disease of the central nervous system that preferentially affects the optic nerves and spinal cord. Classic NMO or Devic's disease is characterized by concurrent episodes of optic neuritis (ON) and transverse myelitis (TM). The current criteria for a diagnosis of NMO requires the presence of ON and TM and two out of the three supportive criteria: 1) MRI evidence of a contiguous spinal cord lesion extending three or more vertebral segments, 2) initial brain MRI not diagnostic for MS, and 3) NMO IgG seropositivity. NMO spectrum disorder (NMOSD) is diagnosed in patients with isolated ON or TM who have the NMO IgG antibody, which is potentially pathogenic and has high specificity for this group of diseases.
In the present study, Mealy et al report their initial findings from analysis of data of 187 patients with NMO/NMOSD from three centers who have the expertise in the diagnosis and treatment of these disorders. Eighty-six patients out of the 187 had NMO IgG seropositive NMO, 40/187 had NMO IgG seronegative NMO, and 61/187 had a seropositive NMOSD. The average age at onset was 41.1 years, female to male ratio was 6.5:1, 47.6% were Caucasian, and 36.9% were African American. These patients were followed for a mean of 6.8 years. The disease was recurrent in 94.1% of patients with a relapse rate of 1.3 events/year. Magnetic resonance imaging (MRI) of the spine at the time of acute events was available in 84.0% (157/187) of patients. Lesions were distributed equally in the cervical and thoracic spine and most of the lesions were longitudinally extensive. Brain MRI findings were available in 80.7% (151/187) patients. Among those for whom brain MRI was available, 40.4% was reported as normal, 47.0% had non-specific white matter changes, 12.6% had MS-like lesions, and 19.9% had brainstem lesions. Most of the patients who had brain stem lesions were of African descent. Among patients who had cerebrospinal fluid analysis for oligoclonal bands, only 12.1% had two or more oligoclonal bands.
In this study, when compared to patients with multiple sclerosis (MS), NMO patients on average were older and the female to male ratio was higher than in MS and more similar to other systemic autoimmune diseases like systemic lupus erythematosus and Sjogren's disease. The incidence in African Americans was disproportionately high and most of the patients with brain stem involvement were African American. As previously reported in earlier studies, most patients had some abnormalities on their brain MRI and a minority of patients had oligoclonal bands in their CSF. Of important note, 29.4% of these patients had been diagnosed as having MS prior to the correct diagnosis of NMO/NMOSD.
The objective of this study was to explore the feasibility of establishing a multicenter collaborative effort to study rare diseases such as NMO/NMOSD. Based on their initial analysis and the potential it holds for further study, they conclude that establishing a national consortium of centers to study NMO/NMOSD is feasible and such an integrated approach would enable better understanding of the disease and provide greater opportunity for research.
Commentary
Until the discovery of the NMO IgG antibody in 2004, NMO/NMOSDs were considered a variant of MS. It is now evident that that NMO is distinct from MS based on immunopathology, disease course, and treatment responses. It is a relatively rare entity with an estimated worldwide prevalence of 0.52 to 4.4 per 100,000 people. Most of our knowledge about these conditions has been from publications reporting on analysis of data from relatively smaller numbers of patients being followed at individual centers and treatment options are often decided based on case reports or at best case series. A comprehensive study of such diseases requires pooled resources form multiple centers. This study demonstrates the relevance of such a collaborative effort and that such an approach is feasible. In a relatively rare entity, such as NMO/NMOSD where even at present a significant number of patients are misdiagnosed as MS and not optimally treated, such an effort is needed to gather data from a large number of patients and establish disease characteristics. Only such an approach will lead to the possibility of meaningful research and clinical trials which will result in better understanding of these diseases and ultimately better management of these patients.
Based on a retrospective analysis of 187 patients with neuromyelitis optica (NMO) or an NMO spectrum disorder from three medical centers, the authors report their initial findings on the epidemiology of NMO/NMO spectrum disorders.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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