Silent Progressive Brain Atrophy in Clinically Stable Neuromyelitis Optica A Comparative Proof-of-Concept Study

Background. Recently we demonstrated progressive corpus callosum atrophy occurring even in clinically stable multiple sclerosis (MS) patients (Figueira G., et al. Arq Neuropsiquiatr 2022;80(4):405-409), but literature data on brain atrophy in neuromyelitis optica spectrum disorder (NMOSD) patients are still scarce. Objectives. We investigated the longitudinal evolution of brain atrophy in clinically stable MS and NMOSD patients. Method. We compared longitudinal MRI data of 14 NMOSD (Wingerchuk, 2015), 148 relapsing remitting MS (McDonald 2001), and 23 control patients, followed regularly with clinical and imaging studies available on baseline and 5 years. All patients had at least 3 conventional MRI available studies with proper protocol leading to a reliable evaluation of activity and progression in at least 5 years. Clinical evaluation included annualized relapses rate and EDSS evolution at least annually, for at least 5 years. MRI data included gadolinium positive lesions or new/enlarging T2W lesion as well as the annualized evolution of corpus callosum index (CCI), measured as previously described (Figueira F., et al. s. Arq Neuropsiquiatr. 2007 Dec;65(4A):931-935) Results. Patients with NMOSD were older and had EDSS scores higher than MS patients. Their mean CCI annual reduction was 0.477, ranging from 0.372 to 0.569, close to cut off and values situated between the stable and the progressive MS group. Conclusion. In this small sample of 14 apparently “stable” NMOSD patients over 7 years follow up period, CCI was able to detect a reduction quite similar to that we see on relapsing remitting MS ones. More robust data are required, with a more significant sample, stratifying for clinical phenotypes and serologic status, but it seems reasonable to state that brain volumetry technique might be a useful tool for monitoring the real state of treatment response.