Том 42, № 8 (2016)

It has traditionally been accepted that the speech-related brain function is located in some strictly determined areas of the left hemisphere: Broca’s area in the posterior part of the inferior frontal gyrus (Brodmann area 44, BA44) and Wernicke’s area in the posterior part of the superior temporal gyrus (BA22). Modern neuroimaging data including functional magnetic resonance imaging (fMRI) expand our knowledge about speech networks in the brain. Using our own speech tasks (paradigms) with sentence reading and sentence continuation tests, we studied the distribution of the neural speech-related network in healthy subjects and its reorganization in patients with different forms of aphasia. During data processing obtained in the control group we found activation of classic speech areas (Broca’s and Wernicke’s ones) and their right-hemisphere homologues, but the volume of the left-hemispheric activations prevailed. Bilateral activation in the inferior parts of the precentral (BA4) and postcentral (BA1) gyri, in the cerebellar hemispheres, and in the visual cortex (BA17–18) was also revealed. The activation in Broca’s and Wernicke’s speech and speech areas in the group of patients was related to the localization of the brain lesion: in the case of lesion in the corresponding area the activation was shifted towards the stroke area periphery. Additional regions of activation, including the superior parietal lobule (BA7), angular and supramarginal gyri (BA39–40), etc., were recorded in both hemispheres in patients with aphasia. It has been shown that the paradigm used in the current study optimally demonstrates speech-related brain network. The obtained data will help to broaden our comprehension of the brain structures involved in the process of speech and understand their role in the recovery of impaired speech functions.

Transcranial magnetic stimulation (TMS) is a new technique that results in neuron excitation using alternating magnetic fields. According to recent reports, high-frequency TMS could be an effective treatment for drug-resistant central post-stroke pain (CPSP). The present case report describes the clinical observation of two patients with CPSP with different lesion localisations and volumes. High frequency (10 Hz) TMS of the primary motor cortex of the affected hemisphere was used in each patient. After stimulation, we recorded a significant reduction in pain on a visual analogue scale (VAS). However, after the end of treatment with TMS, pain gradually returned to previous levels after 3–4 months.

Considerable burden of stroke along with continuously increasing cost of medical help to stroke patients in Russia prompt to search for new and more efficient strategies for stroke prevention. These strategies should encompass improvement of people’s awareness of stroke symptoms and risk factors, as well as accessible information on how to modify the risk factors. Here we present the Stroke Riskometer™ app for smartphones which fulfills the abovementioned criteria. This tool has been developed based on research data and is acknowledged by the international medical community. Russian version is also available. The app allows to determine personal risk of stroke in adults within the next 5 to 10 years; it also helps to reveal personal risk factors for stroke and appropriate ways to mitigate these factors. We believe that wide use of this app in Russia will help to significantly reduce incidence of stroke.

An important mechanism of neuronal plasticity is neurogenesis, which occurs during the embryonic period, forming the brain and its structure, and in the postnatal period, providing repair processes and participating in the mechanisms of memory consolidation. Adult neurogenesis in mammals, including humans, is limited in two specific brain areas, the lateral walls of the lateral ventricles (subventricular zone) and the granular layer of the dentate gyrus of the hippocampus (subgranular zone). Neural stem cells (NSC), self-renewing, multipotent progenitor cells, are formed in these zones. Neural stem cells are capable of differentiating into the basic cell types of the nervous system. In addition, NSC may have neurogenic features and non-specific non-neurogenic functions aimed at maintaining the homeostasis of the brain. The microenvironment formed in neurogenic niches has importance maintaining populations of NSC and regulating differentiation into neural or glial cells via cell-to-cell interactions and microenvironmental signals. The vascular microenvironment in neurogenic niches are integrated by signaling molecules secreted from endothelial cells in the blood vessels of the brain or by direct contact with these cells. Accumulation of astrocytes in neurogenic niches if also of importance and leads to activation of neurogenesis. Dysregulation of neurogenesis contributes to the formation of neurological deficits observed in neurodegenerative diseases. Targeting regulation of neurogenesis could be the basis of new protocols of neuroregeneration.

Optical coherence tomography (OCT) and multifocal electroretinography (mfERG) data using 61 hexagons are presented in three groups of patients: (1) with multiple sclerosis (MS) and optic neuritis (ON) (14 patients), (2) with ON of unknown etiology (19 patients), and (3) with ON of infectious etiology (12 patients). In the patients with MS, the correlation of the latency of the P1 component of mfERG in the parafovea with the retinal thickness in the central zone in all the quadrants of the fundus (except for the superior one) and with the total macular volume has been revealed, which makes it possible to use this mfERG parameter as a marker of MS progression. The results of the current study have demonstrated that the density ratio R₁/R_x may be used as an additional marker of the acute stage in diagnostic process. Patients with ON of infectious etiology were characterized by a decrease in the retinal thickness in the parafoveal zone of the temporal and inferior quadrants and reduction in the density and amplitude of P1 in all the rings.

Changes of cerebral perfusion and the condition of collateral blood supply in patients with internal carotid artery stenoses may have a prognostic value for effective blood flow restoration after revascularization of the internal carotid arteries (ICAs). To determine the patterns of cerebral perfusion changes in patients with ICA stenoses before and after surgical treatment, a clinical CT perfusion study of 41 patients with moderate to severe ICA stenoses was performed. Perfusion CT (PCT) had been conducted in 17 patients with moderate ICA stenoses (50–69%) and in 24 patients with severe ICA stenoses (70–99%) 3 times: before intervention (balloon angioplasty with stenting or carotid endarterectomy), on the 3rd to 7th day, and within 1 to 3 months after surgery. Scanning was performed at the level of the basal ganglia and semioval centers. In patients without ICA stenosis (control group of 39 individuals), PCT was conducted once. We found that surgical recanalization of the ICA leads to normalization of the cerebral blood flow parameters in the perfusion area of the middle cranial artery, as evidenced by a decrease of MTT and CBV and an increase of CBF to values comparable to those in the control group. However, blood flow restoration in the anterior and posterior watershed areas, which are known to be mostly affected under chronic hypoperfusion conditions, was observed only in patients with a complete circle of Willis (CW) and moderate ICA stenosis. Therefore, severe stenosis (>70%) and the incomplete CW are the prognostic factors for inadequate blood flow restoration after revascularization in patients with ICA stenoses.

The Parkinson’s disease (PD) pathology is not limited to degeneration of the nigrostriatal dopaminergic system, but also includes the wide lesion of various regions of cerebral cortex. In our study we aimed to identify differences in the brain cortical thickness in patients with early and advanced PD using MRI morphometry. Sixty-seven patients with Hoehn–Yahr stages 2 and 3 were examined. All patients underwent MRI with subsequent post-processing and estimation of cortical thickness values in different brain regions. Significant differences in the visual and cingulate cortex, fusiform gyri, frontopolar zone of a dominant hemisphere, and Brodmann’s areas 1, 2, 3, and 4 of a non-dominant hemisphere were obtained. These data show relationship between the non-motor manifestations of PD and degeneration of certain cortical regions of the brain.