Structural and Functional Neuroimaging in the Investigation of the Brain Neuroplasticity in Post-Stroke Patients (Literature Review)

Despite the deep theoretical study of the problem of stroke, morbidity, mortality and disability in this pathology remain high, which requires a search for new approaches to the tactics of patients. In this situation, the efforts of doctors are aimed at minimizing the size of the focus of ischemia due to the effect on the ischemia zone. The lifespan of neurons in the ischemia zone in humans is extremely variable, depending on various factors, including the occlusion of the vessel, the adequacy of collateral blood flow, and the sensitivity of tissues to ischemia. Nevertheless, it is known that in the post-stroke period, the brain undergoes a series of different stages of recovery, during which the central nervous system is able to reorganize neural networks and, as determined as neuroplasticity of the brain. Direct visualization of the presence and prevalence of the ischemic zone can contribute to the development of optimal treatment tactics, which will be based on the true state of the lesion locus in each particular patient. Methods of neuroimaging help assess the overall structural and functional disorders associated with stroke and, more importantly, help predict the restoration of body functions. Thus, diffusion tensor imaging (DTI), allows determining the extent of damage to white matter, by identifying areas of the brain with increased total diffusion. The diffusion of free water in tissues due to Brownian motion of molecules is estimated by the DTI method. Magneto-resonance spectroscopy (MRS) is a marker of metabolic changes in undamaged neural tissue and serves as an indicator of brain function. With the help of MRS, it is possible to quantify the level of metabolites in different parts of the brain. Changes in brain neuronal activity in the post-stroke period are manifested by abnormal activity of the sensorimotor cortex and can be determined using functional magnetic resonance imaging (fMRI). The mechanism of fMRI is based on the fact that when the oxygen level in the blood fluctuates, the magnetic resonances signal changes, which can be estimated with the help of special equipment. Increased activity of groups of neurons leads to a significant increase in their metabolism. As a result, there is a sharp increase in oxygen consumption by blood. The article presents an overview of the data based on the use of structural and functional methods of neuroimaging, with the aim of assessing recovery in the post-stroke period.