Rheoencephalography Research Articles

Results of Alzheimer'S Disease Endovascular Treatment Method

Treatment of Alzheimer's disease is one of the most pressing problems. We present the results of Alzheimer's disease endovascular treatment based on catheter revascularization and recovery of collateral and microvascular bed of the brain by means of transluminal exposure to low-energy laser radiation. The study included 52 patients aged 34-79 (average 65) who had had Alzheimer's disease for a long time. 46 (88.5%) patients underwent surgery including: Group (CDR-0) - 4 (8.7%) - with an increased risk of acquiring the disease - patients suffering from growing memory disorder, without much cognitive disorder and manifestations of dementia whose 2 or more immediate family members had Alzheimer's disease; Group (CDR-1) - 15 (32.6%) - with mild dementia, mild cognitive disorder and moderate manifestations of the disease (history of up to 2 years); Group (CDR-2) - 20 (43.5%) - with moderate dementia, persistent cognitive disorder and more severe manifestations of the disease (history of up to 6 years); Group (CDR-3) - 7 (15.2%) - with severe dementia, gross cognitive disorder and late-stage Alzheimer's disease (history of 7-12 years). The examination plan included CT or MRI with subsequent calculation of the volume of the temporal lobes of the brain, scintigraphy (SG) of the brain, rheoencephalography (REG) and cerebral MUGA. Surgical interventions in Group CDR-0 were performed prophylactically, and in the other groups in 1-12 years after the symptoms appeared. Revealed basic X-ray morphological features of Alzheimer's disease are: atrophy of the temporal lobes of the brain combined with reduction of capillary blood flow in fronto-parietal and temporal regions, multiple arteriovenous shunts in the same regions, early venous shunts and passive venous congestion in fronto-parietal region. Indications and contraindications for the treatment are described. Positive results such as reduction of dementia, improved memory and diminished cognitive disorder have been achieved in all cases though the degree was different in each group of patients. The treatment of patients in different stages of Alzheimer's disease helps not only halt further disease progression, but may also cause its regression. It cannot be excluded that the process is accompanied by brain tissue regeneration.

Studies in Rheoencephalography (REG)

Abstract This article presents an overview of rheoencephalography (REG) – electrical impedance measurements of the brain – and summarizes past and ongoing research to develop medical applications of REG for neuro-critical care and for primary prevention of stroke and cardiovascular disease. The availability of advanced electronics and computation has opened up the potential for use of REG technology as a noninvasive, continuous and inexpensive brain monitor for military and civilian applications. The clinical background information presented here introduces physiological and clinical environments where REG has potential for use in research and clinical settings. REG studies over the past three decades have involved in vitro and in vivo groups (animal and human), including more than 1500 measurements and related electronic and computational results and practical applications. In vitro studies helped researchers understand the flow/volume relationship between Doppler ultrasound and electrical impedance signals and supported development of REG data processing methods. In animal studies, REG was used to monitor the lower limit of cerebral blood flow (CBF) autoregulation (AR) using a newly developed algorithm. These animal studies also confirmed correlations between REG and measurements of carotid flow (CF) and intracranial pressure (ICP). Human studies confirmed the applicability of REG for detecting cerebrovascular alteration, demonstrating the usefulness of REG in the field of stroke/cardio-vascular disease prevention. In these studies, REG was compared to known stroke risk factors and to results obtained using carotid ultrasound measurements. An intelligent REG system (Cerberus) has been developed for primary stroke prevention. In these studies, the biologically relevant variables of the REG signal were pulse amplitude (minimum – maximum distance) and duration of the anacrotic (rising) portion of the REG pulse wave. The principal limitation of REG for clinical application is the lack of pathological and physiological correlations. The studies presented here have initiated such inquiries, but many clinical questions about the pathophysiological background of REG remain unanswered. These results demonstrate that REG development is a multidisciplinary subject with relevance for medicine (vascular neurology and neurosurgery intensive care); electronic engineering; mathematics, and computer science (data processing). It is hoped that information presented in this article will provide assistance to those involved in REG research, particularly in development and clinical applications.

Effect of metal fragments in brain on electrical monitoring: In vitro and in vivo rat studies

Preliminary results showed, measurements by rheoencephalography (REG) very promising as a practical, noninvasive continuous monitoring modality of traumatic brain/blast injuries. As the impact of metal fragments on the REG signal is unknown, we report here results of our study .The in vitro study confirmed that impedance pulse amplitude waves do not change in the presence of metal (needles) placed between electrodes. In vivo studies: rats under anesthesia (10 rats, 101 trials) were measured after implantation of EEG and REG electrodes in the brain. Metal fragments were represented by 18 g needles inserted and removed between EEG and REG electrodes. Data were stored in a PC. EEG recording typically showed amplitude decrease; REG showed transitory amplitude increase after placement of a needle into either hemisphere. Removal of needles caused a decrease in REG amplitude after a transitory increase. The change in REG amplitude statistically was non-significant. Cerebral blood flow (CBF) autoregulation(AR) persisted following placement of metal fragments in rat brain.

Influence of volume and flow change on the electrical impedance signal (in vitro)

On the basis of preliminary results, rheoencephalography (REG) shows promise as a practical, noninvasive and continuous monitoring modality of brain injuries. However, REG literature reflects uncertainty about whether the signal reflects flow or volume. Presented here are results of in vitro studies manipulating flow/volume to model clinical conditions (such as brain ischemia and vasospasm) while recording the electrical impedance signal. A loop was created using tubing filled with 0.9 % NaCl. This loop was comprised of a Doppler in-line flow probe connected to an ultrasound flow meter, a peristaltic pump, a pressure transducer and home-made electrical impedance measuring cell, incorporating a balloon catheter. Bipolar impedance amplifiers were used for measuring impedance pulse waves. Data were stored on a PC and processed off-line. This in vitro study confirmed that 1) Doubling flow rate influenced the pulse amplitude and mean flow of the Doppler signal; 2) Doubling flow rate had no influence on the amplitudes of the pressure or electrical impedance signals; 3) An increase in amplitude was observed in the pressure and electrical impedance signals when the first derivative was taken. 4) Balloon inflation decreased electrical impedance and Doppler flow pulse amplitudes; 5) With balloon inflation, Doppler and electrical impedance signals showed an identical relationship to decreased flow (R2=0.966).

The correction of vertebral joint dysfunctions changes cerebrovascular and cerebrospinal fluid functional parameters improving some Primary Respiratory Mechanism parameters

Introduction The driving force of the Primary Respiratory Mechanism (PRM) is the fluctuation of the Cerebrospinal Fluid (CSF) and the cerebrospinal vascular circulation. 1–4 Dynamic components are appreciated by osteopaths on palpation without reproducibility or research result concordance. 5 The aim of this study is to evidence, by using the equipment-based methods devised by Prof. Moskalenko, any PRM changes induced by osteopathic treatments. The study examines whether the momentary corrections of a given vertebral segment, previously diagnosed as the most important dysfunction at the spinal level (primary dysfunction), improve the rhythm, amplitude, and force of the cranial PRM. Design Pre–post randomised controlled double-blind clinical trial including placebos. Methods Participants: Eighteen male and female subjects aged between 18 and 100 divided into two even groups. Intervention: Step 1: objective osteopathic examination; Step 2: transcranial dopplerography (TCDG) and rheoencephalography (REG) at rest and with the application of functional tests (Transitional Respiratory Arrest and Stoockey Maneuver); Step 3: Group 1 received a vertebral manual input specific for the primary dysfunction while Group 2 received a specific vertebral manual input in a non-dysfunctional area; Step 4: step 2 repeated. Outcome Measures: Pre–post technique equipment-based evaluation using TCDG and REG with data analysed through spectral, pattern and phase analysis. Results PRM amplitude and rhythm showed an increase in Group 1: calculated from cerebrospinal flow and meningeal vasal tone parameters and cerebrospinal fluid displacement from the spine to the skull. Values showed greater changes in Group 1, while for Group 2 the changes were minor, absent or worsened. Conclusions The findings demonstrate cerebral flow and the change in brain vessel tone vary sufficiently after applying a vertebral manual input in the areas of maximum spinal restriction (Group 1). With regard to the vascular flow, an interesting fact is that there is no significant change in cerebral blood flow of the middle cerebral artery in both groups, however, a significant increase in blood flow was detected for both vertebral arteries only in Group 1 after the vertebral input. All changes, in particular the parameters concerning vascular and cerebrospinal fluid flows, could account for the marked increase in only one PRM parameter: amplitude.

The specific features of central nervous system lesions in children with type 1 diabetes mellitus

The specific features of central nervous system lesions were studied in 100 children with type 1 diabetes mellitus (DM), by using the data of a survey, rheoencephalography (REG) and psychological tests (cognitive and emotional processes). The cerebroasthenic syndrome that manifested itself as headache (42%), dizziness (33%), overfatigability and weakness (49%) was diagnosed by the analysis of complaints. REG established that 42% of the children with DM have cerebral circulatory disorders. Psychological tests revealed cognitive disturbances in 74 children with DM, of them 54, 59, 21, and 30 children diminished thinking, mechanical and logical memory, and attention, respectively. Fifty children were found to have emotional disorders as anxiety in 50 children, depression in 32, and aggression in 25. The psychoneurological syndrome in the presence of DM was diagnosed in 33%; it appeared mainly as behavioral deviations (hypersexuality, autism, theft, and falseness). The level of cerebral circulation and cognitive and emotional processes in the examinees correlated with the values of HbA1с. Impairments of cerebral hemodynamics, cognitive and emotional' sphere were encountered in decompensated carbohydrate metabolism more frequently than in compensated and subcompensated DM (p < 0.01 and p < 0.05).

Spatiotemporal pattern of the extracranial component of the rheoencephalographic signal

The use of rheoencephalography (REG) in the clinical practice to evaluate cerebral blood flow is conditional on the finding of a method for removing the extracranial interference caused by the scalp blood flow. To remove this undesirable influence, digital processing based on statistics could be an effective technique if the appropriate data model were applied. This paper focuses on the analysis of the spatiotemporal features of the extracranial REG component, by comparing its morphology and phase shift at several scalp sites. For this purpose, a numerical model of the scalp was employed to assess tissue impedance changes caused by the inflow of a stepwise blood pulse wave. These results were compared with the experimental impedance waveforms recorded on six pairs of adjacent electrodes. The correlation coefficients between each pair of impedance recordings of each subject were always greater than 0.942, showing a mean value of 0.986. This result suggests that the extracranial REG component can be considered as morphologically invariant. On the other hand, negligible phase shifts were observed when mean electrode distances, measured in the blood flow direction, were relatively small, although temporal corrections in the data model would be advisable for longer distances.

Use of rheoencephalography for primary stroke prevention

Stroke is the third leading cause of death worldwide and the most frequent cause of brain damage in adults. Screening for arteriosclerosis at an early stage of disease could detect high-risk individuals and populations before the onset of stroke. Doppler ultrasound, the traditional method to detect carotid disease, is expensive and difficult to administer on a large scale. The aim of this study was to test the applicability of a computerized screening system utilizing rheoencephalography (REG) to identify individuals at high-risk for stroke. REG estimates cerebrovascular alteration caused by arteriosclerosis, expressed as the elongated rise time of the REG pulse wave. Methodology was previously published 1, 2. Data were collected in a rural area (Hungary) using the computerized screening system to record risk factors for arteriosclerosis, including a history of transient ischemic attack. Carotid flow (CF) data measured by Doppler ultrasound were also collected for comparison. A cross-sectional survey was conducted for 546 people (REG, N=390; CF, N=252). Subjects' blood chemistry data and EKG were also assessed. In evaluating elasticity of brain arteries, the REG standard originally established by Jenkner was modified. A REG peak time of 180 ms or above (CF: mean velocity above 40 cm/sec) was considered a cerebrovascular alteration 3. REG and Doppler (CF) data: sclerotic brain arteries estimated by REG were 52.78% (m) and 55.8% (f). Pathologic CF was 29.41% (m) and 39.08% (f). The regression lines of age versus REG rise time and CF in male and female groups were similar, but the slope of REG was about ten times steeper than that of CF 1, 4. Brain vessel responses (CBF autoregulation) have been found to be size dependent. Previous results support the hypothesis that REG reflects CBF autoregulation (arteriolar functioning). Animal studies have shown that REG may reflect CBF autoregulation more accurately than Doppler. These results are consistent with REG literature indicating that an increase in REG rise time indicates decreased arteriolar elasticity. REG rise time may be the earliest sign of cerebrovascular sclerosis, indicating the presence of disease at an earlier stage than Doppler. The computerized system utilizing REG is simple to administer, non-invasive, cheap, and has potential as a tool for mass screenings of target populations.

Rheoencephalographic evidence of complement activation-related cerebrovascular changes in pigs

Intravenous administration of Doxil and other liposomes in pigs can cause severe cardiopulmonary and hemodynamic abnormalities, including pulmonary hypertension, systemic hypotension, falling cardiac output and tachy- or bradycardia with arrhythmia, ventricular fibrillation and cardiac arrest. The phenomenon, which is due to complement activation by the liposome membranes, suggests a model for acute hypersensitivity reactions (manifested in hyper- or hypotensive episodes, chest pain, dyspnea) caused by liposomal drugs in patients. However, some other manifestations (e.g., anxiety, confusion, headache) could not be readily explained by changes in systemic circulation, pointing to possible direct effects of complement activation on the cerebrovascular system. The goal of the present study was to explore liposome-induced changes and changes related to complement activation in cerebral blood flow (CBF) using rheoencephalography (REG), the measurement of changes of electrical impedance in the skull. REG measurements were performed on anesthetized pigs (n = 24 pigs, 57 liposome injections, 19 types of liposomes). Systemic (SAP) and pulmonary arterial pressure, cardiac output, EKG, REG were recorded on a PC. Data were processed off-line. Following liposome infusion, pig SAP decreased robustly, and the changes described above were again observed (massive pulmonary hypertension, systemic hypotension and severe cardiac abnormalities, including falling cardiac output and tachy- or bradycardia with arrhythmia). A significant, transient decrease in REG pulse amplitudes occurred in 40 of 51 cases. A 78.43% decrease in REG amplitude was observed, which lasted only a few seconds. This transient decrease preceded the actual onset of circulatory shock, before changes in pulmonary and systemic arterial pressures, and also preceded a decrease of CO2 levels in exhaled air. In about half of the animals (51.9%), REG pulse amplitude first decreased then increased, an indication of transient cerebral vasoconstriction and vasodilatation, which occurred while SAP was low or falling. In 48.1% of the animals, REG amplitude remained depressed or decreased further. In 26.3 % of the animals, both types of CBF response to cardiovascular shock induced by liposomes were observed. Different liposomes produced no qualitative differences in cardiovascular reactions; increased doses of all liposomes elicited severe reactions. In the Doxil subgroup (n=12), the decrease in REG pulse amplitude was statistically significant (P = 0.003) after Doxil administration; average amplitude decrease was 42.5 16.5 %, and the CBF response was autoregulatory in 91.6 % (11 out of 12). This study gives direct evidence of cerebrovascular changes caused by liposome administration. The fact that the CBF decrease preceded the CO2 decrease during the reaction supports our hypothesis that liposome infusion has a direct impact on cerebrovascular reactivity.

The Role of Computerized Rheoencephalography in the Assessment of Normal Pressure Hydrocephalus

The aim of this study was to determine the relationship between arterial compliance derived from rheoencephalography (REG), and the slope of the regression line between pulse amplitude and mean ICP (AMP/P) recorded during a lumbar infusion study. A hypothetical link between these two variables has been suggested in the past. Resistance to the outflow of cerebrospinal fluid (R(out)) and the slope of the amplitude pressure regression line (AMP/P) were calculated in 62 patients diagnosed with posttraumatic normal pressure hydrocephalus (NPH). In all patients, the changes in cerebral electrical impedance related to the pulsatile component of blood flow were studied noninvasively using computerized rheoencephalography. We classified the REG pulse-related waveform (REGpw) according to the number of the inflection points in the ascending branch, which are a manifestation of the elastic properties of the small arteries. In normal subjects, REGpw corresponded with only one inflection point in the ascending branch (category I). For the purpose of this study, we assumed that the presence of three or greater number of inflection points was characteristic of the regressive changes of the arterial wall (category II). The slope of the AMP/P in patients with the category I REGpw was significantly lower than that in patients with category II (p < 0.05). The association between REGpw category II and the increased slope of the aAMP/P regression line may be related to the transmission of the pulse pressure waveform arterial wall to the CSF compartment, which in turn depends on the elastic properties of the cerebral arteries. The outcome of shunting in patients with REGpw category I was significantly better than that in patients with category II, suggesting that small artery disease may be linked to worse clinical outcomes. Our study indicates that REG examination has potential clinical value in diagnosis and prognosis of NPH.

Cerebrovascular reactivity: rat studies in rheoencephalography

Here we describe a correlative study of cerebral blood flow (CBF) using global, local CBF and carotid flow measurements. The primary objective of this study was to establish a relationship between REG and CBF autoregulation. Rheoencephalography (REG), a rarely used method to measure CBF, is a potential tool of non-invasive continuous life sign monitoring and detection of early cerebrovascular alteration. However, the anatomical background of REG is not clearly understood. Two experimental studies were undertaken on anesthetized rats to define two CBF measurements: (1) CO2 inhalation, and, (2) clamping of common carotid arteries. Measurement of CBF was taken with REG, laser Doppler flowmetry (LDF) and carotid flow by Doppler ultrasound. Data were off-line processed. During CO2 inhalation, the increases in REG and LDF were significant (p = 0.0001), while carotid flow and systemic arterial pressure decreased. During carotid artery clamping, the decrease in REG and Doppler ultrasound was significant (p = 0.0001). REG showed cerebrovascular reactivity, indicating the relationship to arteriolar changes. Compared to LDF and carotid flow, only REG showed the classical CBF autoregulation.

Influence of the scalp thickness on the intracranial contribution to rheoencephalography

In spite of the great efforts made by the scientific community, up to now there is no agreement about the rheoencephalography (REG) capability to reflect cerebral blood flow (CBF). Moreover, a standard procedure and the optimal electrode arrangement have not been established yet. In a previous study, we found, using a classical four-shell spherical model of the head and solving it by numerical methods that, theoretically, there could exist an electrode arrangement to register an REG II free of extracranial contribution. In this paper, we have studied the influence of scalp thickness on the intracranial contribution to REG II. The study has been performed by solving the head model, using in this case analytical methods, and then estimating the partial contribution of CBF pulsatility to REG for a given set of scalp thicknesses. Although our theoretical results validate the previous finding and suggest that, in some cases, an optimal electrode arrangement to register REG II exists, such an arrangement, and even its existence, is very sensitive to the subject's scalp thickness. According to this, there could not exist a universal electrode arrangement suitable for all individuals to register an REG II free of extracranial contribution, since it depends on the subject's physical constitution. This fact could explain the lack of agreement in the literature about REG interpretation.

Quantification of intracranial contribution to rheoencephalography by a numerical model of the head

Objectives: Partial contributions of intracranial and extracranial circulation to rheoencephalography (REG) remain uncertain. The main goal of this work is to determine theoretically the capability of REG techniques to reflect intracranial blood flow. Methods: Head and current injection electrodes were computationally modeled to assess REG sensitivity to brain and scalp conductivity changes. Data obtained were related to tissue perfusions to calculate the partial contribution of cerebral blood perfusion to REG I, REG II and monopolar REG and to assess their amplitudes. Results: When REG I and monopolar REG were used, the theoretical maximum of intracranial contribution was reached with large current injection electrodes, being 8% for REG I and 12% for monopolar REG. However, some specific REG II electrode arrangements showed a nil contribution of the extracranial circulation and a minimum influence of the electrode size. Conclusions: These results may explain the disagreement on REG origin and suggest a theoretically optimum electrode arrangement.

Effects on regional cerebral blood flow of transcendental meditation

Previous blood flow measurements in this laboratory have indicated increased nonrenal nonhepatic blood flow during behaviorally induced rest states, especially during the stylized mental technique of transcendental meditation (TM). We have hypothesized that increased cerebral blood flow (CBF) may account for most of the increased nonrenal nonhepatic blood flow during TM. In this report we describe increased frontal and occipital CBF in TM determined by the electrical impedance plethysmographic methodology known as rheoencephalography (REG), which allows noninvasive, nondisturbing, continuous CBF monitoring. We also report high correlation between increased CBF and decreased cerebrovascular resistance (CVR) during TM, suggesting that a contributing vascular mechanism to the increased CBF may be decreased CVR. Because only a small amount of stage 1 sleep was observed during TM and because stage 1 sleep has been reported to be accompanied by decreased CBF, we believe that sleep did not contribute to the CBF increase. The data of this study are consistent with the hypothesis that blood flow changes during TM comprise a patterned response subserving needs of increased cerebral activity.

A simulation study of intracranial pressure increment using an electrical circuit model of cerebral circulation.

An electrical circuit model of the cerebral circulation is presented. Changes of pulsatile waves of the intracranial pressure (ICP) and the cerebral blood volume (CBV) with ICP increment were investigated by simulation of the cerebral blood flow using this model. The simulation is performed by a small signal approximation using the pulsatile component. The results obtained are able to explain the phenomenon of changes in pulsatile wave of ICP with ICP increment. With regard to the CBV, the modeling results are useful for application to rheoencephalography (REG) using electrical impedance method for noninvasive ICP monitoring.

Changes in the tone of cerebral vessels in patients with bronchial asthma after glomectomy

Frequent complications of glomectomy are headaches and a mild, less-like state for several days or weeks after surgery, and sometimes hemi- and monoparesis. The reasons for these complications have not yet been revealed. In search of their explanation, we decided to study the volumetric blood flow of the brain and the acid-base state (ACS). Volumetric blood flow was studied by rheoencephalography (REG) in 43 patients, and acid base balance - in 100 patients (age from 22 to 67 years). The course of bronchial asthma before the operation in the examined patients was moderate and severe.

A comparison of electroencephalography, rheoencephalography and tests of dyslipidemia in affective syndromes of late onset. : V. Predescu and I. Roman (Bucharest, Rumania)

Objectives: Partial contributions of intracranial and extracranial circulation to rheoencephalography (REG) remain uncertain. The main goal of this work is to determine theoretically the capability of REG techniques to reflect intracranial blood flow.Methods: Head and current injection electrodes were computationally modeled to assess REG sensitivity to brain and scalp conductivity changes. Data obtained were related to tissue perfusions to calculate the partial contribution of cerebral blood perfusion to REG I, REG II and monopolar REG and to assess their amplitudes.Results: When REG I and monopolar REG were used, the theoretical maximum of intracranial contribution was reached with large current injection electrodes, being 8% for REG I and 12% for monopolar REG. However, some specific REG II electrode arrangements showed a nil contribution of the extracranial circulation and a minimum influence of the electrode size.Conclusions: These results may explain the disagreement on REG origin and suggest a theoretically optimum electrode arrangement.