Subcortical brain lesions in different phenotypes of multiple sclerosis and their prognostic significance

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease that affects the CNS and leads to disability. Women suffer more often, and the disease begins earlier than in men. The disease is common among the European race. People living in Northern Europe, the United States, Southern Canada, Australia, New Zealand (more than 50 cases per 100,000 people) have an increased risk of developing the disease. More often the disease develops between 20 and 42 years of age [1–3].

Various combinations of genetic, epigenetic, exogenous, and endogenous factors contribute to the development of the disease, the interaction of which triggers the process of demyelination and neurodegeneration. Approximately 110 different polymorphisms at 103 loci outside the MHC genes are identified in different ethnic groups. The largest number of positive couplings is in the 3q21–24, 6p21 region [4]. Among exogenous factors, the following are considered: vitamin D3 deficiency, consumption of animal proteins and fats, Epstein-Barr virus, herpes 6A, retroviruses. Endogenous factors include endocrine disorders, changes in the composition of the microbiome, biotin levels, reduced activity of the dopaminergic system. The influence of environmental and social factors is of great importance. Many studies are based on the concept of interaction between environmental triggers and genetic susceptibility factors. The connection of MS with increased consumption of proteins and fats in animals, exposure to heavy metals (especially zinc, fat triaryl phosphate), with the presence of arsenic, lead, manganese, carbon monoxide, aluminium, molybdenum in the environment has been revealed [5–6]

Currently, the neurodegenerative component of multiple sclerosis is attracting more and more researchers’ attention [7–8]. One of the criteria for the onset of the neurodegenerative phase of the disease course is the patient’s transition from the remitting phenotype of the disease to the secondary progressive phenotype, in which there is already a significant disability of the patient and a sharp reduction in the possibilities of drug therapy [9].