Combined Use of Clinical, Lesion Topography, and Thalamic Volume Helps Differentiating Multiple Sclerosis from its Mimickers

Abstract

Early diagnosis of multiple sclerosis (MS) is important. Non-specific white matter changes usually confound earlier diagnosis. Cross-sectional, global and regional studies have shown that brain volume estimates are of diagnostic and prognostic relevance to the management of the disease; however, it did not reach an individual patient level of precision. We aimed to use both conventional (subjective lesion count) and advanced (brain volume and thalamic volume) magnetic resonance imaging (MRI) measures to investigate the ability of these measures to differentiate MS from other mimickers. Seventy MS patients and seventy-two age- and sex-matched healthy controls were recruited for this study. A third group of patients diagnosed with MS mimickers who presented with symptoms that might be attributed to MS, and had multiple white matter lesions was also included. Whole brain volume and thalamic volume were evaluated for all groups using FSL software pipelines (SIENAX and FIRST respectively). Z scores were calculated for brain and thalamic volume from healthy controls group and two standard deviations below the mean were considered the cut-off value for comparison. Brain and thalamic volumes differed significantly between the study groups. Brain volume correlated significantly with thalamic volume in healthy controls (p<0.00, r=0.59) and MS group (p<0.00, r=0.76), but not in the MS mimickers group (p=0.26, r=0.27). A significantly low brain volume was observed in 7 MS patients (10%) and a significantly low thalamic volume was observed in 15 MS patients (21%). Only one subject from MS mimickers group showed a significant low brain volume (5%); otherwise no significant thalamic atrophy was observed in this group. Thalamic and brain atrophy occur early in MS. Non-specific white matter changes do not contribute significantly to brain volume changes. Hemispheric volume changes may occur in MS mimickers but not particularly thalamic atrophy. Cross-sectional volumetric evaluation may add some valuable information in distinguishing MS patients from common radiological mimickers of the disease.