Leptomeningeal inflammation is related to cortical thinning in relapsing-remitting multiple sclerosis (S6.008)

Objective: To investigate the relationship between leptomeningeal (LM) inflammation and cortical thinning in multiple sclerosis (MS). Background: Several MRI studies have recently found in vivo evidence of LM inflammation in MS using post-contrast MRI. A recent study found that presence of LM contrast enhancement (LMCE) was associated with reduced cortical gray matter volume over 5 years. Design/Methods: Twenty-nine (n=29) relapsing-remitting (RRMS) patients with LMCE were selected for a sub-analysis of a larger study investigating LM inflammation. All patients were imaged on a 3T scanner with a 3D T1-weighted acquisition along with 3D FLAIRs acquired pre- and post-administration of gadolinium. Cortical reconstruction was performed using the FreeSurfer software. LMCE foci were identified on 3D FLAIR post-contrast images and confirmed using a voxel-wise subtraction image. LMCE foci were mapped onto the cortex and regions of interest (ROIs) were obtained by dilating the individual foci along the surface a differing number of times (n=5, 10, 15, 20, 25, 30, 35, 40). The resulting ROIs were then also mapped onto the contralateral hemisphere. Paired t-tests were used to compare thickness measures of the cortex surrounding individual LMCE foci and the corresponding contralateral region. Results: The number of LMCE in individual patients were either 1 (n=20) or 2 (n=9). Mean cortical thickness surrounding the LMCE was always smaller compared to the contralateral hemisphere, with smaller ROIs showing greater differences. Significantly thinner cortex was found for ROIs corresponding to 10 dilations (−5.95%, p=.030), 25 dilations (−3.42%, p=.046), 30 dilations (−3.17%, p=.025) and trends at 5 dilations (−6.89%, p=095), 35 dilations (−2.32%, p=.061), and 40 dilations (−1.91%, p=.089). Conclusions: Focal leptomeningeal inflammation is associated with reduced thickness of the surrounding cortex in RRMS patients. Disclosure: Dr. Bergsland has nothing to disclose. Dr. Ramasamy has nothing to disclose. Dr. Hojnacki has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with David Hojnacki has received speaker honoraria and consultant fees from Biogen Idec, Teva Pharmaceutical Industries Ltd., EMD Serono, Pfizer Inc, and Novartis. Dr. Weinstock-Guttman has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Bianca Weinstock- Guttman received honoraria as a speaker and as a consultant for Biogen Idec, Teva Pharmaceuticals, EMD Serono, Genzyme&Sanofi, Novartis and Acorda. Dr. Weinstock-Guttman has received research support from Dr Weinstock-Guttman received research funds from Biogen Idec, Teva Pharmaceuticals, EMD Serono, Genzyme&Sanofi, Novartis, Acorda. Dr. Zivadinov has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Robert Zivadinov received personal compensation from EMD Serono, Genzyme-Sanofi, Claret Medical, Celgene and Novartis for speaking and consultant fees. Dr. Zivadinov has received research support from RZ received financial support for research activities from Genzyme-Sanofi, Novartis, Claret Medical, Intekrin-Coherus and Quintiles IMS.