Cognitive Evoked Potentials Research Articles

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.

EVALUATION OF THE EFFECTIVENESS OF ALCEBA IN CHILDREN WITH CEREBRAL PALSY BASED ON POTENTIAL INDICATORS OF COGNITIVE IMPAIRMENT

We examined 72 patients with cerebral palsy at the age of nine to 17 years (mean age 11.33±2.1 years), of which 29 were girls, 43 were boys. Neuropsychological tests were performed (British Picture Vocabulary Scale (BPVS) test for verbal intelligence, Raven's test (Raven Progressive matrices) - to assess non-verbal intelligence and cognitive evoked potentials (CEP). In cerebral palsy, cognitive impairments in the form of disorders of memory, attention, thinking, verbal and non-verbal intelligence, and P300 cognitive evoked potentials tend to deteriorate, conditionally, with an increase in paretic limbs. In addition, the course use of the drug memantine (alcheba) in patients with cerebral palsy has a curative effect on cognitive impairment in this category of patients.

Neurophysiological correlates in diagnosis of cognitive disorders in different clinical types of post-concussion syndrome

Objective — to identify the most frequent clinical types of post‑concussion syndrome (PCS) with cognitive function disorders; to study changes in cognitive evoked potentials (CEP) P300 neurophysiological indices in this cohort.Methods and subjects. A complex clinical study with CEP P 300 recording was performed with a view to determine the presence and degree/severity of post‑traumatic cognitive disorders in 115 men with PCS after a mine‑blast trauma (MBT) they experienced in 2014 — 2017. The age range of the patients was from 18 to 45; time elapsed after MBT — from 6 months to 3 years. We performed neuropsychological testing according to the Montreal Cognitive Assessment (MoCA), the Hospital Anxiety and Depression Scale (HADS) and Asthenic Assessment Scale; MRI of the head; duplex ultrasound spectroscopy; quantitative EEG and CEP P300.Results. Three main types of PCS were identified in the patients: 1st — with predominance of cognitive disorders — 51 cases (44.3 %); 2nd — with predominant affective disorders — 27 (23.5 %); 3rd — with predominant psychosomatic disorders — 37 (32.2 %). CEP P300 latency statistically significantly depended on the severity of cognitive disorders. A statistically significant correlation of P 300 latency with the attention concentration and operative memory on the MoCA scale and a score in the cognitive cluster of the questionnaire «Cicerone» was found. The P300 method was used to define the type of PCS in long‑term period of mild traumatic brain injury.Conclusions. It is suggested that 3 main types of PCS should be identified depending on the predominance and occurrence of apparent significant cognitive disorders and severity of clinical manifestations. Expediency of CEP P300 method application for detection of the presence and severity of cognitive disorders in patients with PCS was confirmed on the basis of patients complains analysis, manifestations, neuropsychological testing results and examinations.

The interrelation of neurophysiological, psychological, and biochemical indicators in patients with occupational chronic mercury intoxication suffering from insomnia

Introduction. Despite the apparent connection of the existing neurological disorders and changes in the psycho-emotional sphere with sleep disorders in patients with chronic mercury intoxication (CRI), these relationships remain the least studied in the clinic neurointoxications. The study aimed to establish a connection between neurophysiological, biochemical, and psychopathological indicators in patients with occupational chronic mercury intoxication and insomnia. Materials and methods. Thirty-six patients took part in the examination in the remote period of CRI. The average age of patients in this group was 50.7±1.05 years, with an average work experience of 14.7±1.05. The authors carried out a psychological examination to determine the levels of depression, anxiety, asthenic state, computed electroencephalography (EEG), cognitive evoked potentials (CEP), polysomnography, the level of neurotransmitters. Results. The study showed that asthenization, when exposed to mercury, occurs due to a decrease in the limbic-hypothalamo-reticular complex activity (the presence of equivalent dipole sources of pathological activity in the area of diencephalic formations (thalamus, hypothalamus) in 56.2±5.6% of cases. The study showed a decrease in activity cerebral cortex, confirmed by weakening the coherent connections of the α-range in the occipital, central and frontal leads according to the data of coherent EEG analysis and changes on the part of the CEP. There was a direct correlation between the level of total sleep time and the serotonin level (rs=0.45), an inverse relationship between the level of depression and histamine level (rs=-0.56). Conclusion. The studies carried out to make it possible to establish the mechanisms of insomnia disorders in chronic mercury intoxication, which cause a weakening of the tone of the cerebral cortex and changes in neurotransmitter metabolism, as well as disorders of the reticular system with limbic structures. The study showed a close direct relationship between neurophysiological, psychological, and biochemical parameters in implementing insomnia in patients with chronic mercury intoxication.

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

Post-Concussion Syndrome after a Mine Blast Injury: Neuropsychological Consequences and Changes of the Cognitive Evoked Potentials (P 300)

In 115 male patients with the post-concussion syndrome (PCS) after a mine blast injury (MBI) and 30 control healthy subjects, complex clinical and instrumental diagnostics were performed. The age of the patients varied from 18 to 45 years, the post-traumatic MBI interval was 0.5 to 3 years, and the MBIs were accompanied by an acoustic (AT) or combined acoustic/barotrauma in 92% of the cases. The standard examination procedure included MRI of the brain, recording of EEG and of auditory cognitive evoked potentials (CEP) (elicited within the oddball paradigm, with special attention to the cognitive component, wave P 300) using the Cicerone and Kalmar NSI questionnaire [7], and neurological and neuropsychological examination using the MoCA, HADS, and asthenic disorder (AD) scales. It was found that, despite a mild intensity of traumatic brain ingury (mTBI) and a rather long duration of post-traumatic period, neuropsychological consequences of the trauma are not fully compensated in a majority of the patients. Up to 90% of persons with PCS demonstrated abnormally high anxiety and depression estimates, psychasthenic disorders, and a more or less expressed decrease in the working ability (WA). These patients were characterized by noticeably longer latencies and much lower amplitudes of P 300 wave at application of the target stimuli than control subjects. Such differences in the parameters of P 300 were clearly associated with the presence of cognitive impairment, severe asthenia, depression, and drop in the WA. It was found that such associations were most intense (statistically significant) in the cases where increments in the P300 latency exceeded the upper limits of age normatives calculated for the population. As is concluded, it is expedient to use recording and analysis of CEP P 300 in the complex diagnostics of cognitive disorders in patients with PCS.

Psychoemotional and cognitive characteristics in patients at the early stages of Parkinson’s disease

The purpose of the study was to assess psychoemotional and cognitive characteristics in patients at the early stages of Parkinson’s disease (PD) by neuropsychological and neurophysiological examinations. Materials and methods. A total of 40 PD patients with Hoehn and Yahr stage I–II (19 patients with stage I PD and 21 patients with stage II PD) were examined. A general physical examination and examination of the nervous system were performed in each group of patients. Neuropsychological characteristics were studied with the Unified Parkinson’s Disease Rating Scale (MDS UPDRS) , the Beck Depression Inventory , Starkstein Apathy Scale, Zung Anxiety Rating Scale, Vein Night Sleep Scale, Boston Stress Test. The cognitive functions were examined by the Montreal Cognitive Assessment (MoCA) scale and cognitive evoked potentials (CEP) P300. Results. A significant increase in PD symptoms (motor and non-motor) severity (P ˂ 0.001) according to MDS UPDRS data depending on PD stage was found. The anxiety level (P = 0.02) according to Zung Anxiety Rating Scale data and apathy level (P = 0.026) measured by Starkstein Apathy Scale, were significantly higher at stage II PD. Cognitive impairments were worsened according to the MoCA scale (P = 0.003) in 87.5 % of the patients. The prolongation of N2 latency in the right frontal area (P = 0.05) and P300 latency in all brain areas (P ˂ 0.01) were observed in stage II PD patients. Conclusions. There was a significant difference between PD symptoms severity (motor and non-motor) in stage I and II PD patients according to MDS UPDRS. Stage II PD patients were characterized by worse cognitive impairments, increased level of anxiety and apathy as compared to stage I PD patients. The difference between cognitive decline severity in patients with PD depending on the stage was confirmed by P300 latency prolongation in stage II PD patients.

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.

Clinical and neurophysiological peculiarities of health disorders in workers in dependence on the vinyl chloride exposure load

Results of the clinical and neurophysiological examinations of 42 workers with operating history at the chemical plant exposed to vinyl chloride (VC) are presented. The purpose of research was the identification ofpeculiarities of clinical manifestations and disorders of the functional activity of the brain in workers at the vinyl chloride production, with taking into account the exposure toxic load (ETL). There were made clinical and electroencephalographic examinations with the detection of cognitive evoked potentials (CEP) and statistical analysis of results with the use of the Mann-Whitney U-test, Fisher’s F-test, calculation of Spearman’s correlation coefficient. The features in clinical picture of the pathology of the nervous system were detected in the form of asthenic disorders with cognitive impairment and autonomic dysfunction syndrome. There was established the increase in the cognitive impairment rate (p = 0.03), the decline in a-EEG activity (p = 0.01) and the worsening of indices of the amplitude (p = 0.011) and latency (p = 0,05) of CEP in extremely high level of ETL in comparison with same indices in the group with moderately high ETL. In the first group there was revealed a statistically significant exceedance of the frequency of hypertension - by 1.6 times, skin diseases - by 9 times, chronic subatrophic rhino-pharyngitis by 1.4 times in comparison with cases from the second group. In the group with moderately high level of ETL there was established the statistically significant inverse correlationship between the ETL and the index of P300 amplitude from the left side (r = -0.38, p = 0.019) and in the group with extremely high level ETL - between ETL and index of the β2 - rhythm (r = - 0.73, p = 0.0008).

Акустические стволовые и когнитивные вызванные потенциалы при хроническом нарушении мозгового кровообращения

Current research aimed to investigate informational content of auditory evoked potentials (EP) (acoustic brainstem and cognitive – mismatch negativity) in assessment of brain functional status and cognitive functions in patients with chronic cerebrovascular disease (chronic CVD). Clinical and neurophysiological examination was performed for 33 patients. Group 1 included 12 patients with chronic CVD in carotid circulation, mean age 61,2 ± 6,3 years old; group 2 included 11 patients with chronic CVD in vertebrobasilar circulation, mean age 62,4 ± 8,0 years old; group 3 (control) - 10 patients without cerebrovascular diseases), mean age 54,6±6,4 years old. For registration of acoustic brainstem EP two series of 1000 stimuli were applied (“click” type, duration 0,1 ms, intensity 65 dB above patient’s hearing level, frequency 10 Hz). Mismatch negativity (MMN) was registered in classic odd-ball paradigm (standard stimulus – a sinusoidal tone with 1000 Hz frequency, deviant – with 900 Hz frequency; interstimulus interval – 500 ms). Results. According to results of MMSE, FAB, test of 10 words repetition and Schulte tables patients with chronic CVD, independently of predominantly affected vascular pool, demonstrated cognitive impairment as compared to control group. In patients with chronic CVD no statistically significant differences of acoustic brainstem EP were revealed, however, MMN amplitude was decreased in comparison with control group. It indicates a shortened lifetime of memory traces and deficit in involuntary attention switching in chronic CVD. Investigation of cognitive EP MMN is informative and can be used in assessment of cognitive impairment.

Evoked brain potentials in patients with chronic vertebrobasilar ischaemia depending on the features of cerebral and regional perfusion

Objective. To evaluate the effectiveness of brain evoked potentials for the objectivization of early cognitive disorders (CD) induced by cerebral and regional hypoperfusion. Materials and methods. The influence of hypoperfusion in vertebrobasilar territory (VBT) on characteristics of cognitive functions in 52 patients with chronic brain ischemia was studied. The following methods were used: clinico-neurological, MRI, SPECT, duplex ultrasound scanning (DUS), EEG, and brain evoked potentials (EP). Results. The patients were split into two groups by DUS scan findings: 1 – those having structural lesions in vertebral arteries (VA), and haemodynamically significant disorders in VBT and 2 – those having none. The examination of patients of the 1 st group showed the following findings: high frequency of blood flow velocity decrease in VA; the tendency of decreasing in volumetric cerebral blood flow in brain segments and hemispheres according to SPECT data; prevalence of ataxia, coordination and long tract signs; high frequency of early CD in the domains of attention and memory; EP index changes. The patients with blood flow decompensation in VBT (according to DUS findings) showed changes in brainstem auditory EP parameters (BAEP): increase of III, IV, V latency peaks and III-V interpeak interval. According to the cognitive EP (CEP) study, the patients of the 1 st group consistently demonstrated higher frequency of N2 peak amplitude decrease, and P300 peak latency increase. Conclusions. Based on DUS scan findings, it is clinically appropriate to distinguish a group of patients with structural and haemodynamically significant disorders in VA. The deviations from the normal indices of CEP and BAEP correlate with CD occurring as a result of cerebral and regional hypoperfusion in VBT.

P300 as an auxiliary method in clinical practice: A review of literature

Cognitive functions can be assessed and followed up over a period of time with cognitive evoked potentials (CEP) P300. In this context, brainstem auditory evoked potentials (BAEP) are most commonly used, but visual evoked potentials (VEP) are utilized as well. The research in this area has demonstrated that these techniques could be used as a supplemental method in diagnostics of numerous diseases such as Alzheimer's disease, mild cognitive impairment, vascular dementia, epilepsy, craniocerebral trauma, Parkinson's disease, multiple sclerosis, and other degenerative diseases. In addition, P300 can also be used as an auxiliary method in the diagnostics of mental disorders conditions such as schizophrenia, panic disorders, narcotic drug addiction, nicotinism, alcoholism, etc. The method assists in monitoring the course of diseases leading to encephalopathy, such as liver and kidney damage and grave anaemia. The advantages of P300 testing are easy application, non-invasiveness, and an unlimited number of potential applications. Moreover, the results obtained with this method are measurable and can be compared.

The study of cognitive evoked potentials (P 300) in boxers with repeated traumatic brain injury

Objective. The purpose is to justify the possibility of early detection of cognitive impairment (CI) in boxers with repeated traumatic brain injury (TBI) through the study of cognitive evoked potentials (CEP). Materials and methods. We examined 52 amateur boxers aged 16 to 31 years, who had had repeated mild TBI. The control group consisted of 30 healthy patients of similar age. Held: clinical and neurological examination, magnetic resonance imaging (MRI) of the brain, ultrasonography (USG) of the vessels of the head and neck, computed electroencephalography (CEEG), neuropsychological testing (NPT), registration CEP P300. Results. The latent period (LP) cognitive complex P300 in the normal range occurred in boxers in 55.77% of observations, while in the control group in 86,67%. The amplitude of the cognitive complex P300 in representatives of the main group was in the normal range in 61,54%, the representatives of the control group - 90.00%. Change the settings of CEP representatives of the core group met more frequently among boxers-men over 26 years, heavyweights and those who had more than 200 fights. The data obtained evidence of decreased cognitive function and memory. Assessing the severity of CI in boxers can say that in all the cases had minor violations. Conclusions. The study CEP can be used even in the preclinical stages of CI for early diagnosis and quality control of regenerative processes and evaluate the effectiveness of corrective actions.

Сlinical and neurophysiological estimation of cognitive function in patients with chronic cerebral ischemia in a period of recovery after surgery

Objective – to estimate the peculiarities of the cognitive function disorders and cognitive evoked potentials (CEP) changes in patients with cerebrovascular deseasis (CVD) in post-operative period and period of recovery.Methods and subjects. 42 patients with chronic cerebral circulation impairment were examined. The patients were operated about the hemodynamic significantly stenosys in internal carotid or/and vertebral artery. The first clinical group included 20 patients, who had acute ischemic stroke; the second group comprised 22 patients without data on ischemic stroke in anamnesis. The methods used: clinical, neurological; neuropsychological testing (NPT), MRI, ultrasound study of the cerebral blood flow, EEG mapping, CEP P300.Results. All studies were conducted in the period of recovery 6 months – 2 years after operation: carotid endarterectomy (14), endovascular angioplasty with stenting (12). Positive changes in blood flow in the area of stenosis, and in the affected intracranial artery and its branches were observed after surgical removal of stenosis. As evidence of cognitive impairment using the results of the NPT decrease by 1.5 σ or more, as a sign of slowing of mental processes – significant increase of the latent period of P300 to 2 σ or more, a significant reduction in the amplitude and increase asymmetry of these indicators. It confirms the correlation of negative effect on the NPT-CEP indicators and next factors: elderly age, decreased blood flow in the proximal segments of the middle cerebral artery by more than 20% of the age norms, absence (significant decrease) in reserve capacity of cerebral blood flow, site of the lesion in the right hemisphere, the presence of seizures.Conclusions. Complex methodology of NTP-CEP allows to educe violations of cognitive functions for patients with CVD in the dynamics of surgery treatment and to control renewal.

Behavioral and neurophysiological study of attentional and inhibitory processes in ADHD-combined and control children

This study compares behavioral and electrophysiological (P300) responses recorded in a cued continuous performance task (CPT-AX) performed by children with attention deficit hyperactivity disorder-combined subtype (ADHD-com) and age-matched healthy controls. P300 cognitive-evoked potentials and behavioral data were recorded in eight children with ADHD (without comorbidity) and nine control children aged 8-12 years while performing a CPT-AX task. Such task enables to examine several kinds of false alarms and three different kinds of P300 responses: the "Cue P300", the "Go P300" and the "NoGo P300", respectively, associated with preparatory processing/attentional orienting, motor/response execution and motor/response inhibition. Whereas hit rates were about 95% in each group, ADHD children made significantly more false alarm responses (inattention- and inhibition-related) than control children. ADHD children had a marginally smaller Cue P300 than the control children. Behavioral and electrophysiological findings both highlighted inhibition and attention deficits in ADHD-com children in the CPT-AX task. A rarely studied kind of false alarm, the "Other" FA, seems to be a sensitive FA to take into account, even if its interpretation remains unclear.

Les explorations neurophysiologiques chez l’enfant cérébrolésé : quand, comment ?

Neurophysiological tests complete clinical and radiological assessments in brain-injured children. Electroencephalogram (EEG) is clearly helpful to diagnose seizures and brain death while auditory evoked potentials (EP) to assess brainstem dysfunction and predict poor neurological outcome in post-anoxic coma. During the acute phase of severe traumatic brain injury (TBI) and bacterial meningitis, early recognition and treatment of convulsive seizures is essential. The incidence of non-convulsive seizures remains, however, high, varying between 7 and 48%. Although costly and time consuming, continuous EEG monitoring techniques may allow improving seizure detection. Therefore, amplitude integrated EEG techniques have been developed; however, they still require assessment in paediatrics. Some EEG patterns are indicative of a final bad outcome, including burst suppression, isoelectric pattern, and status epilepticus. EEG predictive value remains limited and less useful than somatosensory EP (SEP). SEP have excellent predictive value in post-anoxic coma in adults as well as in children (94 to 100%), especially in combination to pupillary reflexes and motor responses assessed after 48 h. In contrast, their predictive value of a good outcome is less reliable. In severe TBI and bacterial meningitis, this performance is also limited. Investigation of cognitive EP or mismatch negativity (MMN) could improve awakening prediction.

Specific changes in auditory cognitive evoked potentials in those who participated in the liquidation of the chernobyl accident: I. Analysis of the early N1 component

An integrated neuropsychological study and recording of auditory cognitive evoked potentials (EPs) using the three-stimulus oddball paradigm was performed in groups of ten subjects who participated in the liquidation of the consequences of the Chernobyl accident aged 50.5 ± 4.0 years and ten healthy subjects aged 47.0 ± 6.0 years. The neuropsychological study showed impairment of higher mental functions, including aspontaneity, fatigability, a decrease in the auditory-verbal and visual memories, and higher motor function deficiency, in cleanup workers (usually referred to as liquidators). Analysis of the amplitude and time characteristics of the P300 component of the auditory cognitive EP showed a decrease in the amplitude of this component in all cortical areas of liquidators in both experimental situations and for all stimuli compared to healthy subjects of the same age. Analysis of the latent period (LP) of P300 in liquidators showed the most distinct increase in the situation of passive audition for all types of stimuli. Analysis of the patterns of reactive rearrangements in different experimental situations showed that the P300 LPs of healthy subjects were similar for all types of stimuli during passive audition and were higher for the significant stimulus in the situation of counting. Liquidators were characterized by an type of response, with the LPs of responses to most stimuli increased in both experimental situations. Analysis of regional changes in the P300 LP showed that the differences in the P300 LP between the groups were the largest in the frontal areas of the left hemisphere. In addition, liquidators exhibited “uneconomical, excessive” responses as compared to normal responses, which suggests a decrease in the attention and memory capacities and could contribute to the impairment of higher mental functions. The changes in the amplitude and time characteristics of the P300 component of auditory EPs suggest deceleration of perception, processing, and analysis of information combined with weakened inhibition. The changes found in liquidators are similar to those observed in elderly people, which supports the hypotheses on accelerated brain aging and on pathological aging caused by low-dose irradiation.

Neurophysiological investigations of hepatic encephalopathy: ISHEN practice guidelines

By studying neuronal activity through neuronal electrogenesis, neurophysiological investigations provide a functional assessment of the nervous system and, therefore, has been used for quantitative assessment and follow-up of hepatic encephalopathy (HE). The different clinical neurophysiological approaches can be classified depending on the function to explore and their sensitivity to HE. The reliable techniques are those that reflect cortical function, i.e., cognitive-evoked potentials (EPs) (P300 paradigm), electroencephalogram (EEG), visual EPs (latency>100 ms) and somatosensory EPs (SEPs) (latency between 25 and 100 ms). Short-latency EPs (brainstem acoustic EPs, SEPs of a latency<25 ms) are in principle insensitive to HE, but can disclose brainstem conduction deficits due to oedema. SEPs and motor EPs can disclose myelopathies. Because of its parallelism to the clinical examination, clinical neurophysiology can complement the neurological examination: (i) to provide evidence of HE in patients who have normal consciousness; (ii) to rule out, at least under some conditions, disturbances of consciousness due to other causes (e.g. drug-induced disturbances, non-convulsive status epilepticus) with the reservation that the mildest degrees of encephalopathy might be associated with an EEG pattern similar to that induced by drugs; and (iii) to demonstrate the worsening or, conversely improvement, of HE in the follow-up period.

P19.8 Assessment of the vegetative comatose state with cognitive evoked potentials (CEPs) and fMRI: Implications for the consciousness model of Damasio and Guerit

P19.8 Assessment of the vegetative comatose state with cognitive evoked potentials (CEPs) and fMRI: Implications for the consciousness model of Damasio and Guerit

FC43.2 Vegetative coma with cognitive evoked potentials (CEPs) and fMRI: Implications for the consciousness model of Damasio and Guerit

FC43.2 Vegetative coma with cognitive evoked potentials (CEPs) and fMRI: Implications for the consciousness model of Damasio and Guerit