RU2272562C1 - Method for determining uremic encephalopathy development degree in patients suffering from chronic renal insufficiency - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: method involves carrying out electroencephalography and cognitive evoked potentials examination on showing binaural acoustic stimulation with 50 ms long pulses which intensity is of 80 dB with 2 s long pauses between stimuli, significant tone frequency equal to 2000 Hz, insignificant one equal to 1000 Hz when shown in pseudo random order. Three series of averaging are recorded with significant tone being repeated 26 times in each of them. The testee counts the significant tones in mind within the second and third series. N2, P3 peak latency and P3 peak amplitude are determined in the first (A1) and in the second (A2) averaging series. Habituation is calculated as A2/A1*100 and A coefficient as ratio of habituation P3 peak amplitude and P3 amplitude of the first averaging series. P3 peak latency being increased when compared to normal reference value in combination with dominated slow electroencephalography activity, severe uremic encephalopathy is to be diagnosed. Habituation P3 peak amplitude growing higher than 100%, P3 peak latency being normal and A coefficient not exceeding 12.31% mcV in combination with electroencephalogram beta-rhythm dominated by frequency below 25 Hz spread allover the whole convex with distinct rhythm mastering response to rhythmic photostimulation in broad frequency bandwidth taking place, mild uremic encephalopathy severity degree is to be diagnosed. Coefficient A value exceeding 12.31% mcV, P3 peak latency being normal in combination with high distant oscillation synchronization, low frequency alpha-rhythm being recorded, zonal amplitude differences being smoothed and theta-waves outbursts being available in frontal central leads, moderate uremic encephalopathy severity degree is to be diagnosed.

EFFECT: high diagnosis reliability.

2 cl, 8 tbl

Description

The invention relates to medicine, namely to neurology, and relates to a method for determining the severity of uremic encephalopathy (UE) in patients with chronic renal failure (CRF). The method can be used in hospitals, clinics, diagnostic centers.

A known method for an objective assessment of cerebral disorders in uremia is electroencephalography (EEG). Changes in the bioelectrical activity of the brain (BEA) according to EEG in patients with chronic renal failure at the pre-dialysis stage of treatment until severe uremic intoxication develops, as well as in most patients with terminal chronic renal failure receiving replacement dialysis therapy, were described as "irritative-dystrophic", with a decrease in alpha rhythm, insufficient alpha-rhythm and violations of its zonal differences, with a predominance of beta waves, with "the identification of slow low-amplitude oscillations" [1, 8, 9, 14]. Thus, only a general, with a diverse, picture of BEA changes in patients with chronic renal failure before the development of pronounced clinical manifestations of uremia was outlined.

When assessing the severity of cerebral disorders in uremia in patients with chronic renal failure, the main attention of the researchers was given to increasing the index of slow activity (that is, the predominance of the waves of theta and delta ranges) according to EEG data [7, 9, 12]. Violations of zonal differences and insufficient severity of alpha-range fluctuations, an increase in the number of high-frequency vibrations (activation and predominance of beta waves) - changes in BEA, often observed in patients with chronic renal failure before the stage of pronounced clinical manifestations of uremia, were not taken into account in determining the degree of RE.

The revealed changes in BEA were interpreted by some researchers as a sign of primary damage to the cerebral cortex, while others as a manifestation of stem (reticular) dysfunction [3, 8, 12]. A clear understanding of the most vulnerable brain structures in chronic renal failure, the dysfunction of which causes clinical and electroencephalographic changes in the early stages of UE, has not yet been formulated.

The core of the clinical picture of UE is the neurobehavioral syndrome, which includes progressive as the UE increases impaired concentration of attention, memory impairment, emotional disorders [6, 7, 9, 14]. EEG reflects only the total BEA of the brain and does not allow an objective assessment of the above cognitive impairment, does not provide information about the features of these disorders. Therefore, in determining the degree of RE, in addition to the use of EEG, it is also necessary to use an objective method that allows you to directly assess the degree of cognitive impairment. This method is the study of cognitive evoked potentials, namely, the method P 300 [4].

There are works devoted to the study of cognitive evoked potentials (using the P 300 technique) in patients with uremia, both receiving dialysis replacement therapy and those at the pre-dialysis stage of treatment [10, 11, 13, 15, 16]. The authors of these studies paid special attention to the latency of the P3 peak, while other indicators, in our opinion, more significant in assessing the initial manifestations of REs (habituation of the amplitude of the P3 peak, changes in the amplitude of the P3 peak of the first series of averagings with the calculation of significant stimuli) remained unexplored.

According to some researchers [15], in patients with chronic renal failure receiving replacement therapy with chronic hemodialysis (HD), the peak latency of P3 is increased. According to other authors [10], P3 latency in patients with HD does not differ from healthy subjects of a similar age.

The contradiction of the given data is noteworthy. In our opinion, this is due to the fact that the authors did not take into account the age-related characteristics of pathological changes in the latency of P3 peak in patients with chronic renal failure. According to our data, in patients with chronic renal failure younger than 30 years, an increase in the latency of the P3 peak can be observed regardless of the success of the correction of uremia and, in this case, reflects residual symptoms and not the severity of UE. The second reason for the contradiction of the presented data is that the assessment of cognitive evoked potentials could be carried out at different times relative to the previous HD session, which significantly affects the result of the study. In the interval between dialysis, the degree of uremic intoxication gradually increases, reaching a maximum at the beginning of the HD procedure. During the hemodialysis session, two processes occur in parallel: the degree of uremic intoxication decreases, which leads to an improvement in P300, but in most cases, cerebral edema increases (as a manifestation of the disturbed equilibrium syndrome), which has a negative effect on cerebral functions. The final change in cognitive evoked potentials during the HD session depends on which of these processes prevails in this particular patient (the EEG data also reflect the latter [1]). Probably, this is precisely the reason for the difference in the results of the study [11], according to which P3 latency in patients with HD significantly decreases during the dialysis procedure, and data from another work devoted to the same problem [16], according to which such an improvement in latency during dialysis not registered.

Thus, to assess the degree of UE in patients receiving hemodialysis therapy, there is a need to standardize the time of the study relative to the previous hemodialysis session, and it is not advisable to assess cerebral functions immediately after the hemodialysis procedure.

When conducting the P 300 technique in patients with chronic renal failure at the pre-dialysis stage of treatment [13], the authors noted an increase in the latency of the P3 peak in some of the subjects, however, they also did not take into account the age-related features of pathological changes in the latency of the P3 peak, did not analyze changes in other parameters during the P 300 technique, which are, according to our data, more sensitive with uremic intoxication.

In recent years, the number of patients receiving dialysis replacement therapy has increased significantly, therapeutic methods are continuing to be actively developed to extend the pre-dialysis phase of treatment of patients with chronic renal failure. It is necessary to clarify that the indication for the beginning of dialysis therapy in patients with chronic renal failure is a decrease in glomerular filtration to 15 ml / min. Thus, the pre-dialysis phase of treatment should end before the onset of severe clinical manifestations of uremia. At present, the study of initial and moderate manifestations of UE is becoming more and more relevant, due to both the preservation of "suburemia" in patients receiving replacement dialysis therapy and the manifestations of uremic intoxication in patients at the pre-dialysis stage of treatment with glomerular filtration levels above 15 ml / min. For a more accurate formulation of the diagnosis, assessment of the dynamics of the state, selection of adequate therapy in such patients, it is advisable to determine the mild and moderate degree of UE. Separation into mild, moderate and severe degrees of UE in patients with chronic renal failure, based on clear criteria, taking into account the complex of data of objective diagnostic methods (EEG, cognitive evoked potentials) - did not exist before. The study of both changes in the total BEA of the brain and cognitive functions allows a comprehensive assessment of cerebral disorders in uremia, determining the degree of RE in patients with chronic renal failure, which increases the objectivity of the study.

The closest technical essence as the prototype of the selected method for determining the severe degree of RE in patients with chronic renal failure using EEG. With progressive RE in patients with chronic renal failure, an increase in slow activity is recorded [7, 8, 12]. The identification of the dominance of slow EEG activity in such patients is a recognized criterion confirming severe brain damage in uremia [8], that is, from our point of view, it can be considered as one of the indicators of severe UE in patients with chronic renal failure. Since EEG reflects only the total BEA of the brain and does not allow an objective assessment of the features and severity of cognitive disorders that are leading in the clinical picture of UE in patients with chronic renal failure, in addition to EEG data, it is necessary to take into account the results of a cognitive study in determining the severe degree of UE in patients with chronic renal failure. evoked potentials, namely, the methodology of P 300.

As mentioned above, in patients with mild to moderate uremic intoxication (in particular, due to the persistence of “suburemia” on dialysis), EEG changes are often observed that do not fit into the framework of an increase in slow activity. In such patients, changes in alpha-range fluctuations (violations of zonal differences in the alpha rhythm, its deceleration) and the predominance of high-frequency fluctuations (beta rhythm) are detected. Thus, such an electroencephalographic criterion as the growth and dominance of slow oscillations cannot be used to assess and classify lighter manifestations of RE in patients with chronic renal failure.

To diagnose the degree of RE, it is necessary to develop criteria that allow, based on a set of objective diagnostic methods (EEG and cognitive evoked potentials), to determine the mild and moderate degree of RE, as well as to increase objectivity in determining the severe degree of RE in patients with chronic renal failure.

The objective of the invention is to develop a method for determining the degree of RE in patients with chronic renal failure, which allows to determine the mild and moderate degrees of RE in patients with chronic renal failure, as well as to increase the objectivity of determining the severe degree of RE in patients with chronic renal failure.

The problem is solved by the fact that patients with chronic renal failure conduct electroencephalography (EEG) in combination with a study of cognitive evoked potentials for presentation of binaural auditory stimulation by pulses of 50 ms, intensity of 80 dB with an inter-stimulus interval of 2 seconds, with a significant tone frequency of 2000 Hz, insignificant - 1000 Hz presented in a pseudo-random order, three series of averagings are recorded, in each of which a significant tone is repeated 26 times, while in the second and third series of averagings, the subject considers significant stimuli in his mind ly; then the activity of the peaks N2, P3, the amplitude of the peak P3 in the first (A1) and in the second (A2) series of averages are determined, habituation is calculated as A2 / A1 * 100 and coefficient A, as the ratio of the habituation of the amplitude of peak P3 to the amplitude P3 of the first series of averagings and a severe degree of RE is determined with an increase in the latency of the P3 peak compared to the norm in combination with the dominance of slow activity on the EEG; a mild degree of RE is determined by increasing the habituation of the amplitude of the P3 peak by more than 100%, the normal latency of the P3 peak, with a coefficient A value not exceeding 12.31% μV in combination with the prevalence of beta rhythm on the EEG with a frequency of up to 25 Hz, which is widespread throughout the convex and distinct reaction of rhythm assimilation to rhythmic photostimulation in a wide range of frequencies; the average degree is determined with an increase in coefficient A above 12.31% μV, normal latency of the P3 peak in combination with increased distant synchronization of oscillations, registration of a low-frequency alpha rhythm, smoothness of amplitude zonal differences and the presence of outbreaks of theta waves in the fronto-central leads.

For patients under 30 years of age, a slight degree of RE is determined only with an increase in the habituation of the amplitude of the P3 peak of more than 100% and the value of coefficient A less than 12.31% μV; the average severity of UE is determined only when the coefficient A is greater than 12.31% μV.

The method is as follows

EEG recording is performed on a 16-channel electroencephalograph of Medecor company from symmetric occipital, parietal, central, frontal and temporal areas according to the international 10-20 system according to mono- and bipolar programs. EEG recording can also be done on any encephalograph. The recording band of the electroencephalogram is from 0.3 to 50 Hz. Stock speed - 30 mm / s. A visual analysis of both the background recording and the reaction to provocative stress tests (rhythmic photostimulation with a frequency of 2 to 20 Hz and hyperventilation for 5 minutes) is carried out. Representation of frequency ranges, amplitude of oscillations, features of the zonal distribution of vibrations of various ranges are evaluated. Recording is carried out in a state of relaxed wakefulness, in a sitting position, with eyes closed.

In addition, a study of endogenous cognitive evoked potentials (P-300 methodology) is carried out to evaluate cognitive functions using the Medelec "Synergy" hardware complex. It is possible to use any other hardware systems for recording cognitive evoked potentials using the P 300 technique. Binaural auditory stimulation is used in the situation of an accidentally occurring event (odd-ball paradigma) with pulses of 50 ms duration, 80 dB intensity with an inter-stimulus interval of 2 s. Significant tone - a frequency of 2000 Hz and a probability of occurrence of 20%. The frequency of an insignificant tone is 1000 Hz. The appearance of a significant and insignificant stimulus in a series is pseudo-random. Three series of averagings are recorded, in each of which a significant tone is repeated 26 times. When recording the first series of averagings, the test subject is not given a task; when recording the next two series of averagings, the subject considers significant (rare) stimuli in the mind. During recording, the patient is with his eyes open. A monopolar lead is used, "active" electrodes are placed at points Cz, Fz according to the international system "10-20", the reference electrode is on the mastoid process, and the ground electrode is at the point Fpz. When registering, the frequency band is from 0.5 to 30 Hz, the transition resistance of the electrodes is not higher than 4 kOhm, the analysis era is 1000 ms. The amplitude-time parameters of the N2-P3-N3 complex are evaluated. The latency of the N2, P3 peaks, the amplitude of the P3 peak (inter-peak amplitude N2-P3) of the first series of averagings with the calculation of significant stimuli (A1), the amplitude of the P3 peak (inter-peak amplitude of N2-P3) of the second series of averagings with the calculation of significant stimuli (A2) are determined. The dynamics of P3 peak extraction during repeated series of averagings (habituation of the amplitude of the P3 peak [5]) is determined by comparing the amplitudes of the P3 peak during the first and second averaging with the calculation of significant stimuli (habituation = (A2 / A1) * 100%). A sign of pathology is an increase in the amplitude of the P3 peak during repeated series of averagings [4, 5], that is, an increase in habituation of more than 100%. In addition, coefficient A was introduced, which is equal to the ratio of the habituation of the amplitude of the P3 peak to the amplitude of the P3 peak of the first series of averagings with the calculation of significant stimuli (coefficient A = habituation / A1 (% / μV)). A severe degree of RE is determined with an increase in the latency of the P3 peak compared to the norm in combination with the dominance of slow activity on the EEG; a mild degree of RE is determined by increasing the habituation of the amplitude of the P3 peak by more than 100%, the normal latency of the P3 peak, with a coefficient A value not exceeding 12.31% / μV in combination with the prevalence of beta rhythm on the EEG with a frequency of up to 25 Hz, which is widespread throughout the convex and a distinct reaction of rhythm assimilation to rhythmic photostimulation in a wide range of frequencies; the average degree is determined with an increase in coefficient A above 12.31% μV, normal latency of the P3 peak in combination with increased distant synchronization of oscillations, registration of a low-frequency alpha rhythm, smoothness of amplitude zonal differences and the presence of outbreaks of theta waves in the fronto-central leads.

For patients under 30 years of age, a slight degree of RE is determined only with an increase in the habituation of the amplitude of the P3 peak of more than 100% and the value of coefficient A less than 12.31% μV; the average severity of UE is determined only when the coefficient A is greater than 12.31% μV.

The duration of all examinations (EEG, methodology P 300) is from 9 to 15 hours. For those receiving HD replacement therapy, all examinations are carried out in the interval from 14 to 24 hours after the end of the hemodialysis procedure.

Distinctive essential features of the claimed method are the following.

1. In addition to electroencephalography (EEG), in patients with chronic renal failure, cognitive evoked potentials are studied by presentation of binaural auditory stimulation with pulses of 50 ms, an intensity of 80 dB with an interstimulus interval of 2 s, with a significant tone frequency of 2000 Hz, insignificant - 1000 Hz, presented in in a pseudo-random order, three series of averagings are recorded, in each of which a significant tone is repeated 26 times, while in the second and third series of averagings, the subject considers significant stimuli in his mind; then the activity of the peaks N2, P3, the amplitude of the peak P3 in the first (A1) and in the second (A2) series of averagings are determined, habituation is calculated as A2 / A1 * 100 and coefficient A, as the ratio of the habituation of the amplitude of peak P3 to the amplitude P3 of the first series of averagings.

2. A severe degree of RE is determined with an increase in the latency of the P3 peak compared to the norm in combination with the dominance of slow activity on the EEG.

3. A mild degree of RE is determined by increasing the habituation of the amplitude of the P3 peak by more than 100%, the normal latency of the P3 peak, with a coefficient A value not exceeding 12.31% / μV in combination with the dominance of the beta rhythm on the EEG with a frequency of up to 25 Hz, distributed over throughout convex and a distinct reaction of rhythm assimilation to rhythmic photostimulation in a wide range of frequencies.

4. The average degree is determined with an increase in coefficient A above 12.31% μV, normal latency of the P3 peak in combination with increased distant synchronization of oscillations, registration of a low-frequency alpha rhythm, smoothness of amplitude zonal differences and the presence of outbreaks of theta waves in the fronto-central leads.

5. For patients younger than 30 years of age, a slight degree of RE is determined only when the habituation of the amplitude of the P3 peak is more than 100% and the coefficient A is less than 12.31% μV; the average severity of UE is determined only when the coefficient A is greater than 12.31% μV.

The invention is based on the first put forward position on the defeat of the diencephalic region as an almost obligate and early sign of UE. Earlier in the literature, clinical signs of local damage to the diencephalic structures were considered as a relatively rare phenomenon in patients with kidney pathology (in 16 people out of 362 patients observed with a diagnosis of chronic pyelonephritis, chronic glomerulonephritis) [3]. This is probably due to the fact that the authors included in the group of diencephalic disorders only a part of the manifestations of diencephalic dysfunction observed in patients with UE, namely vegetative paroxysms in combination with rhythm disturbances of sleep-wakefulness and "... epileptiform seizures with tonic seizures. .. ".

As we already mentioned, the main manifestation of UE in patients with chronic renal failure is neurobehavioral syndrome, which at the stage of initial and moderate manifestations includes impaired concentration, memory impairment, emotional disorders (irritability, anxiety, or, on the contrary, apathy). These patients are also characterized by disturbances in the rhythm of sleep-wakefulness, a decrease or lack of appetite, a number of hormonal disorders, and often manifestations of vegetative lability. The totality of all the listed clinical manifestations, according to modern ideas about the symptom complex of diencephalic disorders [2], is quite within the scope of the defeat of the diencephalic region. Thus, the analysis of clinical data suggests that the defeat of the diencephalic region is the leading and early manifestation of UE.

A group of 34 patients with chronic renal failure was examined, including patients at the pre-dialysis stage of treatment with a glomerular filtration level of more than 15 ml / min, that is, to the stage of pronounced clinical manifestations of uremia, as well as patients with HD and continuous ambulatory peritoneal dialysis (CAPD), with a duration of replacement therapy for more than 6 months. ("Stable" patients). The causes of chronic renal failure were chronic glomerulonephritis, chronic pyelonephritis, polycystic kidney disease. The group of subjects did not include patients who had a history of primary neurological pathology (strokes, brain injuries, epileptic seizures). The comparison group consisted of 30 healthy subjects of a similar age.

According to the results, 97% (33 people) of the examined patients showed bilaterally symmetric changes in BEA. Of these, in 2 patients (both on the treatment of HD), a decrease in the threshold for convulsive readiness of the center-brain structures of the brain stem was recorded. In the remaining patients (91% of the examined, 31 people), two types of BEA changes were observed: in the first case (“rhythm α-1” group), an increase in the distant synchronization of oscillations, registration of a low-frequency alpha rhythm with a smoothing of amplitude zonal differences in combination with outbreaks was revealed theta waves in the fronto-central leads. In the second case (the β-1 rhythm group), the dominance of the beta rhythm (frequency up to 25 Hz), which is widespread throughout the convex with a distinct reaction of rhythm assimilation in a wide range of frequencies during rhythmic photostimulation, was recorded.

According to modern literature data [2], such variants of BEA changes (“rhythm α-1”, “rhythm β-1”) are characteristic for damage to the diencephalic region. Thus, the EEG data confirm the diencephalic level of localization of disorders in EE.

It is known that with verified pathology of the diencephalic region, changes in the EEG corresponding to the "β-1 rhythm" type are detected with a weak pathological effect on diencephalic formations. With a greater degree of impact, an increase in the distant synchronization of oscillations, a “slowdown” of the alpha rhythm with a violation of its zonal distribution and the appearance of theta waves in the fronto-central leads (“rhythm α-1”) are recorded and, finally, a massive effect leads to gross cerebral changes in the form of stable dominance in all areas of slow activity [2]. It should be recalled that the dominance of slow activity is also a recognized criterion for a severe degree of RE [8].

Based on these data, the examined patients were divided according to the EEG results into groups with changes in the total BEA of the brain of the lung (group "β-1 rhythm") and middle (group "α-1 rhythm"). Then analyzed the characteristics of cognitive impairment (according to the results of the methodology P300) in patients of these groups.

According to the calculated data, in comparison with healthy subjects in patients of the “β-1 rhythm” group, that is, with a minimal degree of damage according to the EEG data, when the P300 technique was carried out, a significant increase in the amplitude positioning of the P3 peak was detected, which indicates a violation of activation processes. In patients of the “rhythm α-1” group, that is, with a greater degree of damage according to EEG data, an increase in the habituation of the amplitude of the P3 peak was aggravated and supplemented by a decrease in the amplitude A1, which reflects a further deterioration in the activation processes and the appearance of signs of impaired distribution of attention resources, a decrease in the level of directed attention according to P300. Thus, a trend was revealed in the changes in the P 300 indices as the severity of REs increased: at first the habituation of the amplitude of the P3 peak increases moderately, then, against the background of its continuing increase, the amplitude A1 decreases. For the convenience of dividing the revealed changes in cognitive evoked potentials into the corresponding light and medium degrees of RE, we introduced an additional coefficient A, which allows us to link together the increase in habituation and the decrease in the amplitude of A1. According to the results obtained, in patients with a minimal degree of damage according to the EEG (“β-1 rhythm” group), only an increase in the habituation of the amplitude of the P3 peak is detected in the absence of significant differences compared to the norm of the coefficient A. In patients with a greater degree of damage according to the EEG (“rhythm α-1” group) coefficient A compared with healthy subjects was significantly increased. This served as the basis for determining the criteria for the separation of cognitive impairment into the corresponding mild and moderate degree of RE. The upper limit of the norm for coefficient A was previously determined: when determining the upper limit of the norm for the entered coefficient A, the arithmetic mean (M) and standard deviation (σ) were calculated for this indicator in the group of healthy subjects: M = 5.08% / μV, σ = 2.41, thus, the upper limit of the norm (M + 3σ) was 12.31% / μV.

According to the P 300 methodology, cognitive impairment corresponding to a mild degree of RE is represented by an increase in habituation above 100% (an increase in the amplitude of the P3 peak in repeated series of averaging is considered a pathology sign [4, 5], that is, an increase in habituation is more than 100%) if the patient has a value coefficient A not more than 12.31% / μV. The patient’s identification of an increase in coefficient A above 12.31% / μV makes it possible to determine changes in cognitive evoked potentials as corresponding to an average degree of RE.

Particular attention should be paid to changes in the latency of the P3 peak. As mentioned above, it is this indicator of cognitive evoked potentials that has attracted the most attention of researchers. We examined 110 patients with chronic renal failure, 18 of them at the pre-dialysis stage of treatment with a glomerular filtration level of more than 15 ml / min, 53 for HD and 39 for CAPD, with replacement therapy lasting more than 6 months. ("Stable" patients). The comparison group consisted of 48 healthy subjects. In all the examined, which were divided into 4 age groups, the latency of the P3 peak was determined (according to the results of the P300 method). A significant increase in the latency of the P3 peak in patients with chronic renal failure compared with healthy subjects was found only in the younger age group (from 18 to 30 years). Thus, an increase in the latency of the P3 peak is not characteristic of patients with mild to moderate degree of RE over 30 years of age. In patients younger than 30 years, an increase in the latency of the P3 peak can also be observed with a good correction of uremia and, in our opinion, does not reflect the degree of existing RE, but is a manifestation of residual symptoms. Therefore, for patients with chronic renal failure younger than 30 years, an increase in the latency of the P3 peak is not a significant criterion in determining the degree of RE.

In addition, we analyzed the results of the P300 technique in four patients older than 30 years with terminal chronic renal failure, severe clinical manifestations of uremia (glomerular filtration level below 15 ml / min) before starting dialysis replacement therapy. In three of them, P3 latency was increased (went beyond M + 3σ for a group of healthy subjects of a similar age), and in one patient whose glomerular filtration level was reduced to a lesser extent than in the rest, no significant increase in the latency of P3 peak was detected It was. According to the research results, it can be concluded that the latency of the P3 peak is an indicator of cognitive evoked potentials less sensitive to uremic intoxication compared with the indicators used (habituation, coefficient A). An increase in the latency of the P3 peak compared with the norm in patients with chronic renal failure older than 30 years is one of the criteria for determining the severe degree of RE.

The study of both changes in the total BEA of the brain and cognitive impairment allows a comprehensive assessment of cerebral disorders in uremia, determining the degree of RE in patients with chronic renal failure, which increases the objectivity of the study.

Example No. 1

Patient M., 39 years old. The medical history No. 16162. He was treated at the Peter the Great Hospital, at the Department of Nephrology and Dialysis from November 4 to December 2, 2003. The clinical diagnosis is primary: Polycystic kidney disease. Secondary pyelonephritis. Complications - Chronic renal failure of PA (anemia, azotemia, dyselectrolythemia). Secondary arterial hypertension.

Somatic status: General condition is satisfactory. The skin and visible mucous membranes of normal color, clean. Pulse 76 beats per minute, rhythmic, satisfactory filling and tension. Blood pressure - 140/85 mm Hg With auscultation of the heart - tones are somewhat muffled. In case of percussion - expansion of the borders of the heart to the left by 2 cm. The abdomen is of the correct form, is actively involved in breathing, during palpation is soft, painless. The liver does not protrude from the edge of the costal arch. In the study of mild pathological changes were not detected. Rumbling is painless.

Clinical blood test (5.11.03) - hemoglobin - 119 g / l; erythrocytes - 4.0 · 10 ₁₂ / l, platelets - 183 · 10 ₉ / l, white blood cells - 5.5 · 10 ₉ / l, stick. - 1%, segment. - 60%, eosinophils - 2%, lymphocytes - 32%, monocytes - 5%, ESR - 7 mm / h.

Blood biochemical analysis (5.11.03) - sodium - 148 mmol / l, potassium - 5.4 mmol / l, calcium 2.1 mmol / l, urea - 26.9 mmol / l, creatinine - 0.380 mmol / l, total protein - 82 g / l, ACT - 0.20 mmol / l, ALT - 0.12 mmol / l, total bilirubin - 15 μm mol / l, sugar - 4.8 mmol / l, β - lipoproteins - 37 units.

General analysis of urine (5.11.03) - light yellow, transparent, acidic, beats. weight - 1.008, protein - 0.066 g / l, white blood cells 8-10 in the field of view.

RW (6.11.03) - negative microreaction.

Reberg's test (10.11.03) blood urea - 26.9 mmol / L, blood creatinine - 0.380 mol / L, urine creatinine 61.0 mol / L, filtration 28 ml / min, reabsorption 93%, diuresis per day 1750 ml, daily protein loss 0.28 g / l / 24 hours

ECG (5.11.03) - Sinus rhythm. Hypertrophy of the left ventricle with a semi-vertical electric position of the heart.

Consultation with an ophthalmologist - on the fundus of the eye, the arteries are slightly narrowed, veins of normal caliber.

ECHO-KG (11.28.03) - ejection fraction of 61%, cardiac cavities are not expanded, myocardium is not thickened, contractile and diastolic functions are not impaired. Aorta, valve apparatus - without features.

Ultrasound of the kidneys (5.11.03) - multiple kidney cysts.

Neurological examination (11.25.03): Complaints of irritability, intermittent sleep disturbances (it is difficult to fall asleep).

Neurological history is not burdened.

In neurological status - the consciousness is clear, orientation of all kinds is preserved, speech is normal in pace, it is proactive in the conversation, it answers the questions in essence. Elements of emotional lability. Fields of vision are not changed, mild anisocoria (pupils S≥D), photoreactions - live, eyeball movements in full, nystagmus - no, facial muscles are symmetrical, no bulbar disorders, no sensitive disorders on the face. Trigeminal exit points are painless. Violations of smell, hearing - not detected. Symptoms of oral automatism - no. Force paresis in the limbs, pathological stop signs - not detected. The tone in the limbs is normal. Deep reflexes D = S, moderate liveliness, superficial abdominal reflexes preserved, D = S. Disorders of superficial sensitivity on the trunk and limbs does not show. Vibration sensitivity on the toes and hands is not reduced. Coordination tests are satisfactory. In the Romberg position - steady. Meningeal symptoms - no.

According to the EEG results (11/26/03) - the beta rhythm with a frequency of 14–16 oscillations per second, which is distributed throughout the convex, dominates in the background recording. Rhythmic photostimulation with a frequency from 2 to 20 Hz: “on” effect - distinct, approximate reaction - long. At a photostimulation frequency of 10 to 18 Hz, a distinct rhythm assimilation reaction is observed. During hyperventilation (5 min), the nature of bioelectric activity does not change significantly. Conclusion - Irration of the median structures of the brain at a diencephalic level.

The results of the methodology P 300 are shown in table 1.

Indicator P3 peak latency A1 A2 Habituation Coefficient a Data 350 ms 16.5 18.5 112% 6.78% / uV patient μV μV

Conclusion - there is an increase in the habituation of the amplitude of the P3 peak. The latency of the peak P3 is within the age norm; coefficient A does not exceed the norm boundary.

The conclusion of the neurologist - according to the obtained clinical and electrophysiological data (EEG results, P300 methods), a diagnosis can be made: Mild uremic encephalopathy.

Example No. 2.

Patient K., 50 years old. Medical history No. 8861. He was treated in the city hospital No. 31 from October 6 to October 17, 2003. Clinical diagnosis - Primary: Chronic glomerulonephritis. Complications - Chronic renal failure of PB (azotemia, dyselectrolythemia, anemia, metabolic acidosis). Secondary arterial hypertension.

Somatic status: General condition is relatively satisfactory. The skin and visible mucous membranes are somewhat pale, clean. Pulse 68 beats per minute, rhythmic, satisfactory filling and tension. Blood pressure - 145/90 mm Hg With auscultation of the heart - a slight systolic murmur over the aorta. With percussion, the expansion of the borders of the heart to the left by 3 cm. Swinging along the lower back is painless. The kidneys are not palpable. The abdomen is of the correct form, actively participates in the acts of breathing, during palpation is soft, painless. The liver does not protrude from the edge of the costal arch. In the study of mild pathological changes were not detected.

Clinical blood test (8.10.03) - hemoglobin - 104 g / l; erythrocytes - 3.3 · 10 12 / l, color indicator - 0.94, white blood cells - 6.2 · 10 9 / l, segment. - 67.8%, lymphocytes - 24.8%, monocytes - 7%, ESR - 19 mm / h.

Biochemical analysis of blood (8.10.03) - sodium - 146 mmol / L, potassium - 4.54 mmol / L, calcium 2.18 mmol / L, urea - 22.4 mmol / L, creatinine - 0.58 mmol / L total protein - 66 g / l, albumin - 35 g / l, ALT - 0.3 mmol / l, total bilirubin - 14 μm mol / l, sugar - 4.5 mmol / l, cholesterol - 4.8 mmol / l , β-lipoproteins - 51.7 units.

General analysis of urine (8.10.03) - light yellow, transparent, acidic, beats. weight - 1.005, protein - 0.663 g / l, leukocytes 3-8 in the field of view, red blood cells - fresh, partially leached 1-3 in the field of view.

RW (8.10.03) - negative microreaction.

Reberg's test (8.10.03) filtration 16.7 ml / min, reabsorption 89%, diuresis per day 2200 ml, concentration index - 11.8.

ECG (10.10.03) - Sinus rhythm. Left ventricular hypertrophy.

Ultrasound of the kidneys (10.10.03) - diffuse changes in the parenchyma of both kidneys.

Neurological examination (12.10.03): Complaints of impaired memory and attention, decreased performance, sleep disturbances (early awakening), irritability, loss of appetite.

Neurological history is not burdened.

In the neurological status - consciousness is not clouded, orientation of all types is preserved, speech is somewhat slowed down, answers questions correctly, in a conversation is not very initiative. The fields of vision are not changed, the pupils are equal, the photoreactions are live, the movements of the eyeballs are in full, the nystagmus is not, the facial muscles are symmetrical, there are no bulbar disorders, and there are no sensitive disorders on the face. Trigeminal exit points are painless. Violations of smell, hearing - not detected. Symptoms of oral automatism - no. Force paresis in the limbs, pathological stop signs - not detected. The tone in the limbs is normal. Deep reflexes D = S, medium vivacity, with the exception of Achilles reflexes, which are reduced. Superficial abdominal reflexes preserved, D = S. It presents hyperesthesia with a hyperpathic hue in the type of "socks" from the level of the ankles. Reduced vibration sensitivity on the toes. No other disorders of sensitivity. Coordination tests are satisfactory. In the Romberg position - steady. Meningeal symptoms - no.

According to the EEG results (10.16.03) - in the background recording the alpha rhythm, with a frequency of 8-9 vibrations per second with a smoothing of zonal differences in amplitude, bilaterally synchronized outbreaks of theta waves in the fronto-central leads. With rhythmic photostimulation, the reaction of assimilation of the rhythm only at a stimulation frequency of 8 Hz. With hyperventilation (5 min) - increased EEG synchronization.

Conclusion - dysfunction of cortical-subcortical relationships at the diencephalic level.

The results of the methodology P 300 are shown in table 2:

Indicator P3 peak latency A1 A2 Habituation Coefficient a Data 332 ms 6.5 7.3 112% 17.2% / uV patient μV μV

Conclusion - there is an increase in habituation, an increase in coefficient A. Latency of peak P3 is within the age norm.

The conclusion of the neurologist - according to the obtained clinical and electrophysiological data (EEG results, P300 methods), a diagnosis can be made: moderate uremic encephalopathy. Initial manifestations of polyneuropathy of the lower extremities.

Example No. 3

Patient F., 24 years old. Medical record No. 35 of an outpatient.

Department of chronic hemodialysis SPbGMA them. I.I. Mechnikova.

Clinical diagnosis: Primary - Chronic membrane-proliferative glomerulonephritis. Complications - chronic renal failure, terminal stage, corrected by dialysis from 04/10/99. Concomitant diseases - arteriovenous fistula of the left forearm. Chronic gastroduodenitis without exacerbation.

Monthly epicrisis: 10.29.02. The duration of hemodialysis is 3 years and 11 months.

Tab. Dialysis mode Patient Lab Data indicator Value indicator Value Type of access Arth. fistula "Dry weight", kg 60,20 Apparatus AK-90S HELL syst., MmHg 130 Dialyzer F7 HELL diast., MmHg 80 t session, hour 4,5 Hemoglobin, g / l 126 Sessions per week 3 ALT, mKat / l 0.4 Qb, ml / min 300 Urea before dialysis, mmol / l 21.3 Heparin, ED 6250 Creatinine before dialysis, mmol / l 0.7 K in dialysate 2.0 Na before dialysis, mmol / l 139.0 Na in dialysate 136 K before dialysis, mmol / l 7.7 Bic in Dialysate 28 Ca before dialysis, mmol / l 1.4 Ultrafiltration, l 3.00 P before dialysis, mmol / l 1.4 Na profile standard Ca · R 2.0 Bic Profile standard Urr 55 UV profile standard Ln KT / V 1,2

Clinical blood test (10.26.02) - hemoglobin - 126 g / l; erythrocytes - 4.2 · 10 12 / l, white blood cells - 5.3 · 10 9 / l, stick. - 3%, segment. - 46%, eosinophils - 2%, lymphocytes - 38%, monocytes - 4%.

Diuresis is absent.

RW (08.08.02) - negative.

HBsAG (08/08/02) - negative

Anti-HCV (08/08/02) - negative

F-50 (08.08.02) - negative.

Somatic status: General condition is satisfactory. The skin and visible mucous membranes of normal color, clean. Pulse 69 beats per minute, rhythmic, satisfactory filling and tension. Blood pressure - 130/80 mm Hg With auscultation of the heart - tones are muffled, clean, no accents. With percussion - the expansion of the borders of the heart to the left by 2 cm. The abdomen is of the correct form, with palpation soft, painless. The liver does not protrude from the edge of the costal arch. In the study of mild pathological changes were not detected. The kidneys are not palpable, lumbar striking is painless on both sides.

Conclusion - The course of the disease is stable. Dialysis is carried out in an adequate mode: indices are within normal limits, hypertension is corrected by hemodialysis. Dialysis regimen changes are not required.

Neurological examination (10.25.02): Complaints of sleep disturbances, increased irritability, periodically notes difficulties in work requiring attention (works as a secretary in the office), there are episodes of “heartbeats” and lightheadedness, which are associated with emotional overload. Recently notes a deterioration in appetite.

Neurological history is not burdened.

In neurological status - consciousness is not darkened, orientation of all types is preserved. He comes into contact willingly. Fixed on his feelings, vegetatively and emotionally labile. When talking, increased exhaustion is not observed. Fields of vision are not changed, mild anisocoria (pupils S≤D), photoreactions - live, eyeball movements in full, nystagmus - no, facial muscles are symmetrical, no bulbar disorders - no sensitive disorders on the face. Trigeminal exit points are painless. Symptoms of oral automatism - no. Force paresis in the limbs, pathological stop signs - not detected. The tone in the limbs is normal. Deep reflexes D = S, live, superficial abdominal reflexes live, D = S. It shows mild hypesthesia of the “socks” type, vibration sensitivity on the toes is reduced. No other sensitive disorders are noted. Coordination tests are satisfactory. In the Romberg position - steady, in the complicated Romberg position - slight staggering. The gait is normal. Meningeal symptoms - no.

According to the EEG results (11.26.03) - in the background recording the alpha rhythm, with a frequency of 9-9.5 vibrations per second with a smoothing of zonal differences, bilaterally synchronized outbreaks of theta waves in the fronto-central leads. With rhythmic photostimulation, the reaction of assimilation of the rhythm at a stimulation frequency of 8 Hz, 10 Hz. With hyperventilation - increased EEG synchronization, an increase in the number of theta waves in the frontal leads.

Conclusion - dysfunction of cortical-subcortical relationships at the diencephalic level.

The results of the methodology P 300 are shown in table 4.

Indicator P3 peak latency A1 A2 Habituation Coefficient a Patient data 336 ms 10.5 uV 14.8 uV 141% 13.43% / μV

Conclusion - there is an increase in habituation, an increase in the coefficient A. The latency of the peak P3 is increased.

The conclusion of the neurologist - according to the obtained clinical and electrophysiological data (EEG results, P300 methods), a diagnosis can be made: moderate uremic encephalopathy. Initial manifestations of sensory polyneuropathy of the lower extremities.

Example No. 4

Patient S., 57 years old. Case histories No. 958. He was treated at the Peter the Great Hospital, at the Department of Nephrology and Dialysis from January 31 to February 23, 2001. The clinical diagnosis is primary: Chronic pyelonephritis. Complications - Chronic renal failure is the terminal stage, is corrected by hemodialysis from 02/08/01. Anemia, azotemia, dyselectrolythemia, metabolic acidosis. Secondary arterial hypertension. Concomitant - arteriovenous fistula of the left forearm.

Somatic status (01/31/01): General condition closer to severe. The skin and visible mucous membranes are pale, traces of scratching on the body. The pulse is 66 beats per minute, rhythmic. Blood pressure - 170/100 mm Hg With auscultation of the heart - tones are deaf, rhythmic. With percussion - the expansion of the borders of the heart to the left to 1. axillaris anterior. The abdomen on palpation is soft, painless. The 3 cm liver protrudes from under the edge of the costal arch. The chest of the correct form, in the acts of breathing is involved evenly. Shortness of breath at rest. The respiratory rate is 23 per minute. Auscultatory - breathing is heard in all departments, hard. The lumbar swelling is painless. The kidneys are not palpable.

Clinical blood test (02/01/01) - hemoglobin - 83 g / l; erythrocytes - 2.9 · 10 12 / l, white blood cells - 5.5 · 10 9 / l, stick. - 1%, segment. - 52%, eosinophils - 2%, lymphocytes - 40%, monocytes - 5%, ESR - 27 mm / h.

Biochemical blood test (02/01/01) - sodium - 149 mmol / l, potassium - 5.4 mmol / l, calcium 2.0 mmol / l, urea - 31.4 mmol / l, creatinine - 0.916 mmol / l, total protein - 67 g / l, ACT - 0.06 mmol / lch, ALT - 0.4 mmol / lch, total bilirubin - 8 μm mol / l, sugar - 4.4 mmol / l, cholesterol - 4.1 mmol / l, β-lipoproteins - 52 units.

Urinalysis (02/01/01) - transparent, acid, beats. weight - 1.007, protein - 0.132 g / l, white blood cells 8-10 in the field of view, red blood cells - fresh, single in the field of view.

RW (02/01/01) - negative microreaction.

Reberg's test (02.02.01) - glomerular filtration 5.6 ml / min, 82% reabsorption, 1250 ml diuresis per day.

ECG (02/01/01) - Sinus rhythm. Incomplete blockade of the left leg of P. Gisa. Left ventricular hypertrophy. Electrolyte disturbances.

Optometrist Consultation - Retinal Angiopathy.

Ultrasound of the kidneys (02/05/01) - signs of nephrosclerosis.

Neurological examination (02/06/01): Complaints of fatigue, sleep disturbances (drowsiness during the day and insomnia at night), lack of appetite. Denies a headache (including during rises in blood pressure). Active complaints of impaired memory, attention, emotional disturbances - does not show.

Neurological history is not burdened.

In neurological status - the patient is inhibited. Speech is slow, answers questions after a pause, in monosyllables. Inspection is negative, comes into contact reluctantly, does not show initiative in the conversation. When surveyed and with little physical activity, it quickly depletes. Fields of vision are not changed, pupils S = D, photoreactions are preserved, convergence is reduced, otherwise the movements of the eyeballs are kept in sufficient volume, nystagmus is not, mimic muscles are symmetrical, there are no elements of hypomimia, bulbar disorders, and there are no sensitive disorders on the face . Trigeminal exit points are painless. Violations of smell, hearing - not detected. Symptoms of oral automatism are mild. There are no clear power paresis in the extremities - no pathological stop signs - have been identified. The tone in the limbs - without clear changes. Deep reflexes D = S, medium vivacity, except for Achilles, which are oppressed. Demonstrates hypesthesia according to the type of “socks” and “gloves”. Vibration sensitivity on the toes is absent, on the fingers is reduced. During movements in the limbs, including when performing coordinating tests, tremor in the limbs, from mild to moderately expressed, is “tremor of action”. In the Romberg position - slight swaying without clear lateralization. Meningeal symptoms - no.

When conducting EEG (06/05/01) - the generalized slow activity of the theta range dominates.

During the P300 methodology (02/06/01), an increase in the latency of the P3 peak (up to 404 ms) is noted.

Conclusion of a neurologist - according to the obtained clinical and electrophysiological data (EEG, method P300), one can be diagnosed with severe uremic encephalopathy. Polyneuropathy of the lower and upper extremities.

To identify parameters that can be divided into degrees of UE, 34 patients with chronic renal failure were examined, including 15 patients at the pre-dialysis stage of treatment without pronounced clinical signs of uremia (glomerular filtration level more than 15 ml / min), as well as patients with HD (10 people) and CAPD (9 people), with the duration of replacement therapy for more than 6 months. ("Stable" patients). The study group did not include patients with high blood pressure (above 150/90 mm Hg), patients who had a history of primary neurological pathology (strokes, brain injuries, epileptic seizures). The comparison group consisted of 30 healthy subjects of a similar age. When EEG was performed in 33 patients with chronic renal failure, bilaterally symmetric changes in BEA were revealed, of which 9 patients showed changes in BEA of the "rhythm (β-1" type, 22 patients had changes in BEA of the "rhythm α-1" type, in 2 patients a decrease the threshold of convulsive readiness of the center-brain structures of the brain stem One patient showed signs of interhemispheric asymmetry with focal pathological activity in the occipital region of the right hemisphere.

In healthy subjects, the following indicators were recorded during the P 300 (M ± m) method: A1 = 19.3 ± 1.8 (μV), A2 = 15.5 ± 1.5 (μV), coefficient A = 5.08 ± 0.44 (% / μV). In all healthy subjects, the habituation of the amplitude of the P3 peak was less than 100% (average 82%). An increase in the amplitude of the P3 peak during repeated series of averages, that is, an increase in habituation of more than 100% is a criterion for deviation from the norm [4, 5].

The indicators recorded during the P 300 methodology in the “rhythm α-1” and “rhythm β-1” groups are shown in table 5.

When determining the upper limit of the norm for the introduced coefficient A, which increases in the “rhythm α-1” group, the value M + 3σ was calculated: M = 5.08% / μV, σ = 2.41, thus, the upper limit of the norm was 12 , 31% / μV.

According to the results, an increase in the habituation of the amplitude of the P3 peak is above 100% in the presence of coefficient A falling within the normal range according to the P 300 methodology, combined with BEA changes of the “β-1 rhythm” type according to EEG data, is a sign of a mild degree of uremic encephalopathy. The detection of an increase in coefficient A above 12.31% / μV according to the P 300 methodology in combination with changes in BEA according to the “rhythm α-1” type according to EEG is a sign of moderate uremic encephalopathy.

Particular attention was paid to changes in the latency of the P3 peak in patients with chronic renal failure. We examined 110 patients with chronic renal failure, 23 of them at the pre-dialysis stage of treatment without pronounced clinical manifestations of uremia (glomerular filtration level more than 15 ml / min), 48 on HD and 39 on CAPD, the duration of replacement therapy was more than 6 months. ("Stable" patients). The group of patients did not include patients with high blood pressure (above 150/90 mm Hg), patients who had a history of primary neurological pathology (strokes, brain injuries, epileptic seizures). The comparison group consisted of 48 healthy subjects.

In all examined patients, which were divided into 4 age groups, the latency of the P3 peak was determined according to the results of the P300 method. The indicators for the groups (M ± m) are shown in table 6.

Significant differences compared with the norm were determined only in the group of patients from 18 to 30 years old (p <0.001). For all other groups, no significant differences were found for this indicator.

A sign of pathology is an increase in the latency of the peak P3 greater than the value of M + 3σ for the values of their age [4]. The upper limit of the latency norm of peak P3 for different age groups according to the results of the examination of 48 healthy subjects is shown in table 7.

Data reflecting the distribution of latency values of peak P3 in patients with chronic renal failure of different age groups relative to the average value of this indicator (M) in healthy subjects of a similar age are shown in table 8.

It is noteworthy that the indicators in the table are "shifted" to the right only in the younger age group, which reflects the "typical" increase in the latency of the P3 peak for patients 18-30 years old even with good correction of uremia.

For comparison, we studied cognitive evoked potentials (using the P 300 technique) in four patients with terminal chronic renal failure and severe clinical signs of uremia over 30 years old (38 to 59 years old) who were not yet receiving dialysis replacement therapy. In three of them, the latency indices of the P3 peak exceeded the value of M + 3σ for the corresponding age group, and in one patient the glomerular filtration level was reduced to a lesser extent than in the rest and the latency of the peak P3 was within M + 3σ.

The data obtained demonstrate that an increase in the latency of the P3 peak in patients older than 30 years is a sign of a severe degree of RE. Thus, for patients with chronic renal failure older than 30 years, an increase compared to the norm of latency of the P3 peak according to the P 300 methodology is one of the criteria for determining a severe degree of RE, and for mild and moderate degrees of RE this indicator should not exceed the normal range. In patients with chronic renal failure younger than 30 years, when determining the mild and moderate degree of RE, it is impossible to focus on normal latency indicators of the P3 peak, since an increase in the latency of the P3 peak in such patients may reflect residual symptoms, and not the degree of available RE.

The inventive method, in contrast to the prototype, allows to determine the mild and moderate degrees of RE in patients with chronic renal failure, as well as to increase the objectivity of determining the severe degree of RE in patients with chronic renal failure due to a combined study of EEG and cognitive evoked potentials using binaural auditory stimulation.

Literature

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2) G. Boldyreva The electrical activity of the human brain with damage to the diencephalic and limbic structures. Moscow. "Science" MAIK "Science / Interiodica" 2000.

3) Glorizova T.G., Hondkarian O.A., Shultsev G.P. The state of the nervous system in chronic kidney diseases. Moscow. "Medicine", 1980.

4) Gnezditsky V.V. Evoked brain potentials in clinical practice. Moscow. MEDpress-inform 2003: 112-130.

5) Gordeev S.A., Ryabokon I.V., Fedotov A.V., Tabeeva G.R., Wayne A.M. Assessment of the state of non-specific brain systems in patients with panic disorder using the method of cognitive evoked potentials P300. Bulletin of Experimental Biology and Medicine. 2003; 136; 11: 589-591.

6) Ermolenko V.M. Chronic hemodialysis. Moscow. "Medicine" 1982: 189-190.

7) Parfenov V.A. Neurological disorders in somatic diseases and pregnancy. In the book: Diseases of the nervous system. Ed. Yakhno N.N., Shtulman D.R. Volume 2. Moscow. “Medicine”, 2001: 327-328.

8) Povorinsky A.G., Zabolotnykh V.A. Manual for clinical electroencephalography. Science, 1987: 41-42.

9) Sagar S. Toxic and metabolic disorders. In the book: Neurology. Ed. Samuelsa M. Practice. Moscow. 1997: 422-426.

10) Brown W.S., Marsh J.T., Wolcott D., et al. Cognitive function, mood and P3 latensy: effects of the amelioration of anemia in dialysis patients. Neuropsychologia 1991; 29 (1): 35-45.

11) Buoncristiani U., Alberti A., Gabbiotti G., et al. Better preservation of cognitive faculty in continuous ambulatory peritoneal dialysis. Perit. Dial Int. 1993; 13 Suppl 2: 202-205.

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13) Cohen S.N., Syndulko K., Rever B. et al. Visual evoked-potentials and long latency event-related potentials in chronic renal failure. Neurology 1983 Sep; 33 (9): 1219-1222.

14) Jennekens F., Jennekens-Schinkel F. Neurological aspects of dialysis patients. In: Replacement of renal function by dialysis. Edited by John F. Maner. Kluwer Academic publishers for Precht / Boston / Lancaster. 1989: 972-975.

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16) Tensos T.E., Brown W.S., Vaziri N. D., Jennison J.H. Event-related potentials changes during hemodialysis. J. Artif. Organs. 1985 Sep .; 8 (5): 269-276.

Table 5 The dependence of P300 indicators on the nature of changes in the bioelectric activity of the brain: Comparison groups Indicators of the methodology P300 Habituation (%) A1 (μV) A2 (μV) Coefficient A (% / μV) Group “β-1 rhythm” according to EEG data (n = 9) 100 ± 7 (*) 17.9 ± 1.5 17.3 ± 0.9 6.34 ± 1.31 The “rhythm α-1” group according to the EEG data (n = 22) 123 ± 7 (***) 12.2 ± 0.9 (**) 14.6 ± 1.2 12.07 ± 1.63 (***) Note: (*) p <0.05, (**) p <0.01, (***) p <0.001, the significance of differences compared with the group of healthy subjects. Table 6 Latency indices of peak P3 (M ± m) for age groups: Age groups P3 peak latency indices (ms) Healthy subjects Patients with chronic renal failure 18-30 years old 307.5 ± 3.1 (n = 9) 324.6 ± 2.7 (n = 9) 31-45 years old 325.3 ± 4.8 (n = 12) 335.1 ± 2.1 (n = 34) 46-60 years old 345.1 ± 3.2 (n = 18) 346.9 ± 2.2 (n = 49) Over 60 years old 370.7 ± 2.9 (n = 9) 368.9 ± 3.5 (n = 18) Table 7 The upper limit of the latency norm of peak P3 for age groups: Age of the subject 18-30 years old 31-45 years old 46-60 years old Over 60 years old P3 peak latency (ms) 335.4 375.1 385.4 396.8

Table 8 The distribution of latency values of P3 peak in patients with chronic renal failure of various age groups relative to the average value of this indicator (M) in healthy subjects of a similar age: The limits of deviation of latency indices of peak P3 relative to the average value (M) for a group of healthy subjects. From M-3 σ to M-2 σ From M-2 σ to M - σ From M-σ to M From M to M + σ From M + σ to M + 2 σ From M + 2 σ to M + 3 σ More than M + 3 σ 18-30 years (n = 9) - - - eleven% 56% eleven% 22% 31-45 years old (n = 34) - - 21% fifty% 26% 3% - 46-60 years (n = 49) four% fourteen% 22% 36% 22% 2% - 61-75 years (n = 18) 6% 17% 44% eleven% 17% 6% -

Claims (2)

1. A method for determining the severity of uremic encephalopathy (UE) in patients with chronic renal failure (CRF), including conducting electroencephalography (EEG), characterized in that it further conducts a study of cognitive evoked potentials for presentation of binaural auditory stimulation by pulses of 50 ms, an intensity of 80 dB with an interstimulus interval of 2 s, with a frequency of a significant tone of 2000 Hz, insignificant - 1000 Hz, presented in a pseudo-random order, three series of averagings are recorded, in each of which th tone repeated 26 times, while the second and third series of averages says the subject in mind significant incentives; then the activity of the peaks N2, P3, the amplitude of the peak P3 in the first (A1) and in the second (A2) series of averages are determined, habituation is calculated as A2 / A1 · 100 and coefficient A, as the ratio of the habituation of the amplitude of peak P3 to the amplitude P3 of the first series of averagings and a severe degree of RE is determined with an increase in the latency of the P3 peak compared to the norm in combination with the dominance of slow activity on the EEG; a mild degree of RE is determined by increasing the habituation of the amplitude of the P3 peak by more than 100%, the normal latency of the P3 peak, with a coefficient A value not exceeding 12.31% μV in combination with the prevalence of beta rhythm on the EEG with a frequency of up to 25 Hz, which is widespread throughout the convex and distinct reaction of rhythm assimilation to rhythmic photostimulation in a wide range of frequencies; the average degree will be determined with an increase in coefficient A above 12.31% μV, normal latency of the P3 peak in combination with increased distant synchronization of oscillations, registration of a low-frequency alpha rhythm, smoothness of amplitude zonal differences and the presence of outbreaks of theta waves in the fronto-central leads. 2. The method according to claim 1, characterized in that in patients under 30 years of age, a slight degree of RE is determined only with an increase in the habituation of the amplitude of the P3 peak of more than 100% and the value of coefficient A less than 12.31% μV; the average severity of RE is determined only when the coefficient A is more than 12.31% μV.