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Introduction: idiopathic acute transverse myelitis (ATM) is clinically characterized by partial or complete spinal cord syndromes, variable remission rate and a monophasic or recurrent clinical course. Partial forms are traditionally associated with Multiple Sclerosis (MS) while complete myelitis to neuromyelitis optica (NMO). The discovery of an antibody called anti-AQP4 was an important tool to differentiate these two conditions. Its presence in NMO high-risk syndromes was associated with longitudinally extensive spinal cord lesion (LETM) and a greater risk of recurrence or conversion to NMO. No data is available in recurrent ATM concerning the association of anti-AQP4 with the severity of spinal cord dysfunction. Objective: To describe the frequency of seropositivity for anti-AQP4 in recurrent idiopathic ATM and analyze the influence of the antibody in long term prognosis. Methods: The medical charts of 75 consecutive patients with inflammatory ATM receiving care in Hospital da Lagoa between 2000 and 2009 were reviewed. Idiopathic cases with recurrent clinical course tested for the anti-AQP4 were selected. Spinal cord MRI lesions were classified as LETM or non-LETM. FS/EDSS scale was applied at last evaluation. Results: We found 26 patients (21 female and 5 male; 17 white and 9 of African descent). The first myelitis occurred at a mean age of 38.04 ? 12.7 years (range 12-60). The median time of the disease was 40.5 months (12-192). The median time between the first and the second myelitis was 8 months (1-150). The number of myelitis ranged from 2 to 7 per patient. The first ATM was complete in 10 cases and partial in 16. At the last neurological evaluation the median pyramidal, sensory, and bowel and bladder FS scores were 2 (0-5), 2.5 (0-5) and 1 (0-5), with a median EDSS score of 3 (0-9). Only seven patients were evaluated as being severely handicapped. LETM was found in 65.4%. Anti-AQP4 antibody was positive in 26.9%, all of them had LETM. Spinal cord dysfunction and disability at long term were similar in ATM anti-AQP4 positive and negative subgroups. ATM associated with LETM presented an earlier onset, higher severe motor dysfunction and disability at last evaluation and higher positivity to anti-AQP4 antibody (41.2% versus 0%, p=0.024). Conclusions: The frequency of anti-AQP4 in Brazilian patients with recurrent ATM was 26,9%, raising to 41,2% when associated with LETM. The positivity of the antibody had no influence in long term prognosis.

Read More: Anti -AQP4 antibody in idiopathic acute transverse myelitis with recurrent clinical course. Frequency of positivity and influence in prognosis