Cognitive evoked potentials in the diagnosis of post-concussion syndrome due to blast mild traumatic brain injury

Hostilities in the East of Ukraine are characterized by the use of new weapons, including rocket artillery, rocket-propelled grenades and landmines. This has led to an increase in the number of victims with blast mild traumatic brain injury (BMTBI) and the need to provide them with effective assistance and rehabilitation. An important task is to improve the BMTBI diagnosis by specifying the objective criteria for structural and functional disorders of the central nervous system. This will improve the prognosis of the course of BMTBI in the injured and the treatment program, including personalized, to prevent the development of persistent neurological deficit. Objective: to investigate the possibilities of the cognitive evoked potentials (CEP) method for the objective diagnosis of cognitive disorders in post-concussion syndrome (PCS) BMTBI. Materials and methods. The study involved 115 men with PCS (main group) and 30 healthy individuals (control group). The cognitive functions of the study participants were studied using the questionnaire "Cicerone". The neurophysiological method for assessing the functional state of the brain involved the registration of CEP, event-related (P300 CEP). Results. The selection of a subgroup of patients with PCS, characterized by a predominance of cognitive impairments, allowed us to trace the relationship between the results of neurophysiological studies with the cognitive indicators of patients with BMTBI. P300 latency indices are inversely proportional to cognitive assessment the questionnaire "Cicerone" and statistically significantly depend on the severity of cognitive impairment. Conclusions. The CEP P300 method can be an effective means of objectifying the degree of cognitive impairment in patients with PCS due to BMTBI.

A study of changes in cognitive evoked potentials in persons with visual impairment

In this work we have used psychophysiological assessments of the human brain electrical activity according to the classical neurological method for calculating the evoked potential. The experiment was designed to extraction cognitive evoked potentials. Taking into account the characteristic components, the temporal dynamics of the EEG data channels was investigated. This approach allows one to consistently assess the distribution of all components of the evoked potential on the subject's head map. Based on the results of evoked potentials processing, a statistical comparison of the components of evoked potentials in subjects of different groups by channels was carried out in accordance with the Wilcoxon test. Demonstrated for which channels the results significantly differ between the two groups of subjects. The sequence of evoked potential analysis demonstrated in the article suits for adjusting the settings of the “brain-computer” systems for a particular subject and allows to select channels used in further BCI training efficiently.

Physiological Parameters in Various Prognosis of the Acute Period of Haemorrhagic Stroke

Study Objective: To identify the differences in physiological parameters in groups of patients in an acute period of haemorrhagic parenchymatous stroke (supratentorial hemisphere hematomas) with favourable outcome and fatality. Study Design: prospective study. Materials and Methods. We have examined 96 patients with supratentorial haemorrhagic stroke. Haemorrhagic stroke was diagnosed on the basis of neuroimaging results, clinical symptoms and medical history, as well as clinical and laboratory data. A cluster analysis and expert examinations made it possible to divide patients into two groups: 49 patients who died of the acute haemorrhagic stroke and 47 patients with a favourable outcome. We evaluated the level of consciousness, cognitive functions, neurophysiological parameters: electroencephalography (EEG), cognitive evoked potentials Р300, heart rate variability (HRV). Study Results. In patients with a favourable outcome, an overall amplitude of the EEG spectrum was higher vs. patients with lethal outcome (statistically significant results were noted in all leads). A significant increase in the mean frequency of theta waves was seen in both groups, especially in the group with lethal outcomes. When Р300 in patients with lethal outcome was evaluated, a significantly lower P2N2 amplitude in Fz was noted vs favourable outcome group: 5.1 (2.6; 9.1) μV vs 8.9 (5.6; 20.4) μV (U = 148; p = 0.021). A comparative analysis of HRV revealed significant differences only in heart rate (mean R-R): it was lower in patients who died in the acute period of haemorrhagic stroke: 696 (608; 836) ms vs 806 (743; 911) ms (U = 181; p = 0.033). In patients with lethal outcomes, there is an increase in the number of linear correlations in physiological parameters vs. favourable outcome group. Conclusion. Deaths from acute haemorrhagic stroke are preceded by reduction in the basic cortical rhythm, growth in slow waves activity, reduction in the stimuli recognition mechanism activation (according to cognitive evoked potentials Р300). An analysis of the rate of correlation in physiological mechanisms of brain activity regulation (EEG), neurophysiological correlates in stimuli recognition and decisionmaking (Р300), as well as autonomic regulation mechanisms (HRV) shows limited functional reserves in patients with lethal outcomes. Keywords: haemorrhagic stroke, event-associated potential, heart rate variability, correlation analysis.

Peculiarities of an assessment of a cognitive efficacy in multiple sclerosis

A key cognitive deficit in multiple sclerosis (MS) is a poor efficacy of the information processing, with working memory impairments and a decreased speed of the information processing as components of formation of this poor efficacy. Despite of a sufficient number of single cognitive tests and test batteries, there are still essential knowledge gaps and methodological limitations connected with understanding and measurements of the cognitive deficit in MS. To study real reasons of changes of the cognitive efficacy in MS, a neurocognitive testing with the original computerized Set for Assessment of Cognitive Capacity and Switchability (сSACCAS), an assessment of levels anxiety/depression, and an assessment of level of fatigue were performed for 25 patients with MS (including 17 female patients) (with a mean age of 34.14 ± 2.13 years old) and 25 practically healthy persons (including 15 females) (with a mean age of 31.80 ± 2.60 years old). To determine neurophysiological correlates of the cognitive functioning, an examination of cognitive evoked potentials (CEP) was performed. An investigation of the distribution density of results of the MS patients’ testing defined 3 groups among them. These groups had differences on the time of performing of test tasks, the “real mistake ratio”, switchability, parameters of N2- and P3-components of CEP, a localization of a maximal P3 peak. The motor reaction speed was more connected with the attention and the information processing speed, than with a visual-spatial orientation, whereas the fatigue more influenced on the speed of comparison and decision making, than on the attention. In 44 % of cases, the time of reply in tests were increased by a slowing down of assessment of a stimulus modality; in 24 % of cases, a long delay of the reply was connected, besides of a low speed of cognitive processes, with impairments of a working memory. The results obtained confirmed a significance of an integrated approach to understand reasons of changes of the cognitive efficacy and to assess adequately cognitive impairments in MS. Key words: neurocognitive computerized tests, cognitive efficacy, cognitive evoked potentials, multiple sclerosis

Findings of the study of cognitive evoked potentials in persons exposed to radiation

Introduction. After exposure to radiation, an increase in the long-term of cerebrovascular pathology is noted in exposed individuals. Cognitive impairments have a growing importance in the pattern of cerebrovascular diseases which significantly deteriorates social and medical forecast of a patient.The objective of the research is to study cognitive evoked potentials in exposed persons with chronic cerebral ischemia (CCI).Materials and methods. Two groups of patients were examined: the main group consisted of 69 persons exposed to radiation as a result of the “Mayak” PA activity, the comparison group included 110 unexposed residents of the Techa riverside settlements who were diagnosed with chronic cerebral ischemia. The following methods were used in the study: clinical, evaluation method of cognitive evoked potentials (EP), and statistical methods.Results. In the course of clinical examination, it was revealed that the number of people with organic cognitive impairment and syndrome of cognitive decline is statistically significantly higher in the group of the exposed persons with CCI (p < 0.001, p = 0.003, respectfully). It was stated that the studied groups were statistically significantly different in N1 peak latency (ð = 0.030), N2 – P3 inter-peak latency (p = 0.003), N2 – N3 inter-peak latency (p = 0.011).Conclusion. According to the results of clinical examination and study of cognitive EP, cognitive impairments are more expressed in the group of the exposed persons with CCI which is manifested in an increase in the number of patients with syndrome of cognitive decline and organic cognitive impairment in this group; in the change of a latency period of a number of components that characterize both the perception process and the very process of recognition and decision-making.