Anti-AQP4 antibody in idiopathic acute transverse myelitis with recurrent clinical course: frequency of positivity and influence in prognosis

Abstract

BackgroundThe anti-aquaporin4 (anti-AQP4) antibody is specific for neuromyelitis optica (NMO), but is also found in limited forms. The presence of this antibody in acute transverse myelitis (ATM) has been associated with recurrence and conversion to NMO, but the influence on disability has not yet been described.ObjectiveTo describe the frequency of anti-AQP4 in ATM and analyze the influence in long-term prognosis.DesignCross-sectional and retrospective study.MethodsConsecutive ATM cases in a multiple sclerosis center in Rio de Janeiro, Brazil, from 2000 through 2009 were reviewed. Recurrent cases tested for anti-AQP4 were selected. ATM with magnetic resonance imaging spinal cord lesions extending over three or more vertebral segments was classified as longitudinally extensive transverse myelitis (LETM); Kurtzke scale was applied at last evaluation.Outcome measuresFrequency of anti-AQP4; severity of spinal cord dysfunction at last follow-up.ResultsTwenty six patients (21 female:5 male; 17 white:9 African descent) were studied. The first ATM occurred at 38.04 ± 12.7 years. The interval between the first and the second ATM was eight months (1–150) and the number of ATM varied from two to seven. After 40.5 months (12–192) of disease, the median Expanded Disability Status Scale (EDSS) score was three (0–9). Anti-AQP4 antibody was positive in 26.9%. LETM was found in 65.4%. LETM presented later onset, higher disability and higher positivity to anti-AQP4 (LETM 41.2% versus no-LETM 0%, P = 0.024). Dysfunction at long-term follow-up was similar in anti-AQP4 positive and negative cases.ConclusionThe frequency of anti-AQP4 in recurrent ATM was 26.9%, increasing to 41.2% among LETM. Presence of the antibody had no influence on morbidity.