Differences in the spectroscopy of the lesions of the remitting relapsing form of multiple sclerosis shown by magnetic resonance

INTRODUCTION: Multiple sclerosis (MS) is a chronic demyelinating disorder of the central nervous system, characterized by the presence of inflammatory lesions. OBJECTIVE: To analyze the biochemical profile of the demyelinating lesions of the initial forms of MS (remitting relapsing) by analyzing the proton magnetic resonance spectra (1H MRS) to characterize the process of demyelination and relate it to the metabolites and clinical variables analyzed. PATIENTS AND METHODS: We analyzed the largest demyelinating lesions in eight patients with remitting relapsing MS (RRMS) using the technique of single volume 1H MRS (VOI) with short echo time. The spectra of the white matter of two healthy control were used as reference. RESULTS: NAA/Cr and NAA/Cho value ratios decrease and mI/Cr one increase in all spectra lesions as compared to healthy controls. In four of the eight patients, the Cho/Cr was higher than in the controls. Qualitative and quantitative differences in the resonances of macromolecules were observed, related to the biochemistry of the process of demyelination. These differences in NAA/Cr, Cho/Cr, mI/Cr and macromolecules probably represent different stages in the evolution of the plaques. CONCLUSIONS: MRS is a non invasive technique able to observe biochemical variations related to the evolution process of demyelination. Activity of the lesion is shown by the increment of resonances around 0.9 1.3 ppm. An increase in mI seems to occur at an early stage of demyelination and later the NAA is reduced. The initial forms of MS show metabolic alterations in the plaques which are similar to the most advanced forms of MS.