FEATURES OF THALAMIC NEURODEGENERATION IN PATIENTS WITH MULTIPLE SCLEROSIS
Currently the role of CNS structures atrophy in disability development in patients with multiple sclerosis (MS) is undisputed. Particular attention is paid to the atrophy of the thalamus, which is associated with a lot of passing through pathways and determine its sensitivity to changes in various parts of the central nervous system. The causes and sequence of the neurodegenerative processes development in MS are still the subject of scientific debates. The aim of our study was to determine the characteristics of neurodegenerative changes in the thalamus in cohort of MS patients with different severity of disability. The study involved 117 patients with clinically isolated syndrome of probable demyelination and multiple sclerosis, according to McDonald criteria (2010) at the age of 18 to 64 and disease duration varied from 1 to 30 years (6,57+7,18). Examination program included a clinical test and MRI, as well as single-voxel proton magnetic resonance spectroscopy ( <sup>1</sup>H-MRS), performed in 34 patients and 5 healthy volunteers. The results of our study showed that the thalamus atrophy plays an important role in development of disability in patients with multiple sclerosis. It is also reached significance in patients with a more than three points of disability score according to EDSS scale. In carrying out the correlation and analysis of variance data <sup>1</sup>H-MRS statistically significant results were obtained only for the correlation analysis of NAA concentration and severity of disability in the left thalamus, which showed a direct correlation. NAA levels in the right thalamus depending on the severity of the disease were not significantly changed. Comparison of the results of morphometric analysis and <sup>1</sup>H-MRS data leaded to conclusion that a decrease of the thalamus volume is mainly due to structural damage of the pathways, with relative preservation of gray matter. The findings may contribute to the formation of therapeutic approaches aimed at preventing the development of disability in patients with MS.