Influencing Factors Of Neuromyelitis Optica Relapsing Rate

Objective:Explore the influencing factors of neuromyelitis optica (NMO) relapsing rate.Methods:We conduct a retrospective review and follow-up of 50 patients who had been diagnosed with NMO between January 2004 and March 2011 at the Neurology Department of The First Affiliated Hospital of Fujian Medical University. For our study we included patients who fulfilled the revised criteria proposed by Wingerchuk et al in 2006,and excluded those: (1)without brain MRI data; (2)with abnormality in vision evoked potential (VEP), but without histories related to blurred vision or visual loss; (3) that had clinical manifestation but free of imaging evidence of spinal cord lesion. Research factors add up to 10, including: gender, age of onset, symptoms of onset, NMO-IgG, oligoclonal band(OB) of cerebrospinal fluid, IgG index, Brainstem involvement, the maximum length of a single spinal cord lesion, immune parameters, and prophylactic agent. The relevance between these factors and the annual relapsing rate of NMO is explored by using chi-square test, Fisher's exact test, t/t'test, Spearman rank sum test and other statistical methods. In addition, it is explored whether the NMO-IgG test results are in association with certain factors such as brain stem involvement and the maximum length of a single spinal cord lesion.Results:Inspection of brain MRI was undertaken by all of the 50 NMO patients, to find out : 15 cases of brain stem involvement (Medulla oblongata in 14 cases, 1 case of pons) and the rest free of brain stem involvement; 12 cases out of the brain stem involvement group suffer an annual relapse rate≥0.8, while only 14 cases in the group free of brain stem involvement suffer the same annual relapse rate. ( Chi-square test, P = 0.035). Other factors such as gender, Age of onset, symptoms of onset, NMO-IgG, oligoclonal band(OB) of cerebrospinal fluid, IgG index, the maximum length of a single spinal cord lesion, immune parameters, prophylactic agent, show no statistical significance. NMO-IgG serum positive was significantly related with the maximum length of a single spinal cord lesion (t'test, P = 0.039). Conclusion:Imaging brain stem involvement is suggestive of NMO patient's unstable condition and easy-to-recurrence. Association between Serum NMO-IgG positive and the maximum length of a single spinal cord lesion suggests that the antibody may be related to the activity of the disease. Accordingly, the adoption of the antibody titer may achieve the quantitative monitoring of disease activity. However, this study did not specify the maximum length of a single NMO spinal cord lesion may be related with annual relapsing rate.