MS patients lacking oligoclonal bands in the cerebrospinal fluid have less global and regional brain atrophy


Diagnosis, monitoring and biomarkers:
Detection of oligoclonal immunoglobulin G bands (OCB) in the cerebrospinal fluid (CSF) is one of the most sensitive biomarkers for diagnosing multiple sclerosis (MS). Due to the complexity and heterogeneity of MS, multivariate methods were applied in this study to be able to observe patterns of regional atrophy, which can discriminate between the OCB groups. A detailed analysis of global brain measures was also conducted.

Based on previous studies, the prior hypothesis was that OCB presence in CSF would be associated with a more severe MRI phenotype, manifesting greater vulnerability of the deep gray and white matter structures but not cortical or juxtacortical regions. Twenty-eight OCB-negative and thirty-five OCB-positive patients were included. Clinical information was recorded using the Swedish Multiple Sclerosis Registry (SMSReg). OCB status was determined by isoelectric focusing and IgG-specific Immunofixation.
All patients were scanned in the same 1.5 T Siemens MR machine. Cortical reconstruction and volumetric segmentation was performed using the FreeSurfer 5.1.0 image analysis suite. The brain volume (BV) was calculated by adding up the total gray matter (GM) and total white matter (WM) volumes. As MS progresses, the brain volume tends to decline while CSF increases. Therefore, lower BV/CSF index values represent greater brain shrinkage. The two OCB groups did not differ in age, gender, disease course, and disability (EDSS). However, OCB-positive patients had a lower age of onset and consequently longer disease duration and treatment duration.

Significant variables were entered as covariates in the corresponding statistical analyses. OCB-positive patients showed greater global brain atrophy as measured by the BV/CSF index. In particular, OCB-positive patients had decreased total WM volume and increased total CSF volume, but they did not differ from OCB-negative patients in total GM volume. Although OCB groups did not differ in the total GM volume, regional analyses showed that basal ganglia, diencephalon, cerebellum, and hippocampus were significantly important in OCB group separation, displaying more volume loss in the OCB-positive group. Regarding the total amount of WM lesions, OCB-positive patients had increased volume of lesions, in alignment with previous studies.

Authors: Ferreira D, Voevodskaya O
Source: J Neuroimmunol. 2014 Jun 26. pii: S0165-5728(14)00181-7. doi: 10.1016/j.jneuroim.2014.06.010. [Epub ahead of print]
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