Objective: Neuromyelitis optica and its spectrum disorder (NMOSD) can present similarly to relapsingremitting multiple sclerosis (RRMS). Using a quantitative lesion mapping approach, this research aimed to identify differences in MRI brain lesion distribution between aquaporin-4 antibody-positive NMOSD and RRMS, and to test their diagnostic potential.Methods: Clinical brain MRI sequences for 44 patients with aquaporin-4 antibody-positive NMOSD and 50 patients with RRMS were examined for the distribution and morphology of brain lesions. T2 lesion maps were created for each subject allowing the quantitative comparison of the 2 conditions with lesion probability and voxel-wise analysis.Results: Sixty-three percent of patients with NMOSD had brain lesions and of these 27% were diagnostic of multiple sclerosis. Patients with RRMS were significantly more likely to have lesions adjacent to the body of the lateral ventricle than patients with NMOSD. Direct comparison of the probability distributions and the morphologic attributes of the lesions in each group identified criteria of "at least 1 lesion adjacent to the body of the lateral ventricle and in the inferior temporal lobe; or the presence of a subcortical U-fiber lesion; or a Dawson's finger-type lesion," which could distinguish patients with multiple sclerosis from those with NMOSD with 92% sensitivity, 96% specificity, 98% positive predictive value, and 86% negative predictive value. Neuromyelitis optica (NMO) is an inflammatory demyelinating condition of the CNS with a predilection for the optic nerves and spinal cord. NMO spectrum disorder (NMOSD) is a term used to encompass NMO (with both optic neuritis and myelitis) 1 and limited phenotypes such as recurrent optic neuritis or myelitis. It is an autoimmune disorder, mediated in most cases by antibodies to the aquaporin-4 (AQP4) water channel, 2,3 and for the majority of patients serum AQP4 antibodies (AQP4-abs) can be detected with an immunoassay. 4 Making a definitive diagnosis of antibodynegative NMOSD can be challenging because the more prevalent relapsing-remitting multiple sclerosis (RRMS) can present similarly (e.g., with attacks of optic neuritis and myelitis). 1,5,6 It is vitally important to distinguish these 2 conditions: patients with NMOSD require long-term immunosuppression to prevent devastating relapses, and disease-modifying treatments for RRMS such as b-interferon can worsen NMOSD.
Conclusion:7,8 Hence, we need other markers to help promptly identify those who should be antibody tested, and to diagnose seronegative disease.MRI is the best noninvasive tool we have for visualizing the pathology of neuroinflammatory diseases in vivo, and has proven particularly useful in identifying patients with longitudinally extensive transverse myelitis (LETM), which is highly suggestive of NMOSD.