Assessment Of Cerebral Circulation Research Articles

Assessment of cerebral circulation through an intact skull using imaging photoplethysmography

The feasibility of assessing the parameters of cerebral hemodynamics without skull trepanation using imaging photoplethysmography with illumination in the near-infrared spectrum range was demonstrated for the first time. The results were obtained when studying changes in blood flow in the rat brain in response to short-term respiratory failure (apnea test). Translation of the results into clinical practice will be useful for the development of a method for non-invasive assessment of cerebral blood flow in patients with cerebrovascular diseases.

Substantiation of the additional prescription of magnetotherapy in the complex of rehabilitation of children with concomitant diseases of the nervous system during remission of cancer

Introduction. The increase in the number of children with oncological diseases requires development of effective methods of medical rehabilitation. Purpose: To determine the effectiveness of the use of low-frequency magnetotherapy (LFMT) in children with diseases of the nervous system, manifested in the period of remission of oncological diseases (OD) in the complex of sanatorium rehabilitation (SRR). Methods: Children with OD at the stage of rehabilitation in a sanatorium underwent a clinical examination: medical history, concomitant pathology, complaints, clinical examination, assessment of neurological status; instrumental studies: electroencephalography (EEG) - assessment of the bioelectrical activity of the brain; echoencephalography (EchoEG) - assessment of CSF dynamics; Doppler ultrasound (USDG) - assessment of cerebral circulation. For 25 children with concomitant diseases of the nervous system during the period of OD remission (17 people) and solid tumors (8 people), in addition to the general complex of SRR, magnetotherapy was prescribed for the cervical-collar zone according to the following method: magnetic induction 20 - 30 mT, exposure 10 - 15 minutes, every other day, for a course of 5 procedures. Results: The use of the therapeutic complex TFR with the additional prescription of magnetotherapy can reliably reduce childrenʹs complaints in remission of the OD for the impaired activity of the nervous system. According to the USDG indicators, statistically significant positive changes in cerebral hemodynamics were established. The results of ultrasound echoEG indicate the improvement of CSF dynamics. According to the EEG data, positive changes in the state of brain electrogenesis were established. Conclusion: The effectiveness of LFMT in children in the period of remission of oncohematological diseases with concomitant diseases of the nervous system has been substantiated. Keywords: children, oncological diseases, sanatorium rehabilitation, low-frequency magnetic therapy,

Assessment of cerebral circulation in a porcine model of intravenously given E. coli induced fulminant sepsis

BackgroundThe aim of the present work was to assess cerebral hemodynamic changes in a porcine model of E.coli induced fulminant sepsis.MethodsNineteen healthy female Hungahib pigs, 10–12 weeks old, randomly assigned into two groups: Control (n = 9) or Septic Group (n = 10). In the Sepsis group Escherichia coli culture suspended in physiological saline was intravenously administrated in a continuously increasing manner according to the following protocol: 2 ml of bacterial culture suspended in physiological saline was injected in the first 30 min, then 4 ml of bacterial culture was administered within 30 min, followed by infusion of 32 ml bacterial culture for 2 h. Control animals received identical amount of saline infusion. Systemic hemodynamic parameters were assessed by PiCCo monitoring, and cerebral hemodynamics by transcranial Doppler sonography (transorbital approach) in both groups.ResultsIn control animals, systemic hemodynamic variables and cerebral blood flow velocities and pulsatility indices were relatively stable during the entire procedure. In septic animals shock developed in 165 (IQR: 60–255) minutes after starting the injection of E.coli solution. Blood pressure values gradully decreased, whereas pulse rate increased. A decrease in cardiac index, an increased systemic vascular resistance, and an increased stroke volume variation were observed. Mean cerebral blood flow velocity in the middle cerebral artery did not change during the procedure, but pulsatility index significantly increased.ConclusionsThere is vasoconstriction at the level of the cerebral arterioles in the early phase of experimental sepsis that overwhelmes autoregulatory response. These results may serve as additional pathophysiological information on the cerebral hemodynamic changes occurring during the septic process and may contribute to a better understanding of the pathomechanism of septic encephalopathy.

Assessment of Cerebral Circulation in the Acute Phase of Subarachnoid Hemorrhage Using Perfusion Computed Tomography

Primary brain damage, caused by acute ischemic changes during initial hemorrhage, is an important cause of death and disability following subarachnoid hemorrhage (SAH). However, the mechanism underlying the reduction in cerebral circulation in patients in the acute stage of SAH remains unclear. The goal of this study was to clarify this mechanism with the aid of perfusion computed tomography (CT). We prospectively evaluated 21 patients who had been undergone perfusion CT within 3 hours of SAH onset. Mean transit time (MTT) was estimated. Forty circular regions of interest 5 mm in diameter were delineated in the cortical region of the bilateral hemispheres on perfusion CT images. Neurological condition was graded with the Hunt and Hess scale, and initial CT findings were graded with the Fisher scale. We defined a good outcome as a modified Rankin scale (mRs) score of ≤2 at 3 months after SAH onset. Global MTT was an independent predictor of outcome. The global MTT of patients with poor outcomes was longer than that of patients with good outcome. Furthermore, global MTT correlated significantly with Hunt & Hess grades, and disturbances in higher cerebral function. Hemodynamic disturbances frequently occur after SAH. These abnormalities probably reflect the primary brain damage caused by initial hemorrhage. Perfusion CT is valuable for detecting hemodynamic changes in the acute stages of SAH.

PP082. Ophthalmic artery doppler for identification of severe preeclampsia in pregnancies complicated by hypertension

Hypertension is the most common disorder that occurs during pregnancy and one of the main causes of maternal mortality worldwide. Among the hypertensive disorders that affect pregnancy, preeclampsia (PE) is the major cause of maternal mortality, maternal morbidity, perinatal death, prematurity and intrauterine growth restriction. The acute cerebral complications in PE account for at least 75% of maternal death. Central nervous system hemodynamic modifications in PE are a controversial issue. Neurological involvement in PE-eclampsia syndrome fulfills the criteria of posterior reversible encephalopathy syndrome (PRES). The pathophysiology of PRES is still under investigation. Assessment of cerebral circulation is challenging. Noninvasive techniques, especially transcranial Doppler sonography, are becoming more widely used to evaluate cerebral flow. Ophthalmic artery Doppler is a noninvasive examination used to study central vascular flow that has been shown to be a promising method in the evaluation of pregnant women with hypertension. The aim of this study was to compare the ophthalmic artery Doppler indices observed in singleton pregnant women complicated by hypertension (study group) and to correlate the indices observed in hypertensive pregnant women with those observed in normal pregnant women (control group). Ophthalmic artery Doppler indices of 30 mild and 30 severe pre-eclamptic women and 30 pregnant women with chronic hypertension (CH) at 20-40weeks of gestational age (GA) were compared. The control group consisted of 289 healthy pregnant women. Resistance index (RI), pulsatility index (PI), and peak ratio (PR) were determined in the right eye. The mean and SD were calculated for each group. Analysis of variance (ANOVA) was used to compare Doppler indexes means between groups. As significant differences were determined by ANOVA analysis, each group was compared by the Tukey method. Receiver operating characteristics (ROC) curves were used to determine the predictive power of ophthalmic artery Doppler indexes for the identification of severe pre-eclamptic women. P<0.05 was considered statistically significant. Significant differences were found between the values obtained for RI, PI, and PR in severe PE women compared to the other groups (study and control). The mean and SD for IR, IP and PR in mild PE, severe PE and CH groups were respectively 0.73 (±0.06), 1.63 (±0.35) and 0.65 (±0.10); 0.63 (±0.09), 1.13 (±0.31) and 0.89 (±0.12); 0.73 (±0.07), 1.66 (±0.49) and 0.66 (±0.14). The mean and SD for IR, IP and PR in normotensive pregnant women were 0.75 (±0.05), 1.88 (±0.43), 0.52 (±0.10). The optimal cut-off values for IR, IP and PR for the identification of severe pre-eclamptic women determined by roc curves was 0.657, 1.318, 0.784 (sensitivity and specificity were 0.633 and 0.919, 0.733 and 0.888, 0.833 and 0.974, respectively). The area under the ROC curve for IR was 0.787(95% CI: 0.68-0.89), for IP was 0.797 (95% CI: 0.69-0.90) and for PR was 0.886 (95% CI: 0.80-0.96). Ophthalmic Doppler is a useful method in the identification of severe PE. PR was best ophthalmic Doppler index at discriminating between severe PE and pregnant women with mild PE or chronic hypertension as determined by roc curve.

Assessment of cerebral circulation in normal fetuses by three-dimensional power Doppler ultrasonography

To assess the three-dimensional power Doppler ultrasonography (3D power Doppler) vascular indices in the middle cerebral artery (MCA), anterior cerebral artery (ACA) and posterior cerebral artery (PCA) territories. A cross-sectional study was carried out on 111 normal pregnancies between 26 and 34 weeks. The MCA, ACA and PCA territories closest to the transducer were scanned and volumes were calculated by using the VOCAL (Virtual Organ Computer-aided Analysis) program. The 3D power Doppler indices--vascularization index (VI), flow index (FI) and vascularization-flow index (VFI) were calculated. Scatter graphs, Pearson correlation coefficients (r) and linear regression models were used. Only the FI-MCA (r=0.38 and p<0.001), VFI-MCA (r=0.23 and p=0.016) and FI-PCA (r=0.191 and p=0.040) had a low correlation with gestational age. The other 3D power Doppler indices VI-MCA (r=0.153 and p=0.150), VI-ACA (r=0.105 and p=0.271), FI-ACA (r=0.154 and p=0.106), VFI-ACA (r=0.134 and p=0.161), VI-PCA (r=0.105 and p=0.270) and VFI-PCA (r=0.126 and p=0.180) showed no statistically significant correlation with gestational. It was observed a low correlation between gestational age and the FI-MCA, VFI-MCA and FI-PCA.

Predictive value of color doppler neuro-sonography for the development of neurological sequels in newborn infants with hypoxic ischemic encephalopathy

The use of color Doppler neurosonography (cD-US) allows simultaneous examination of parenchymal and vascular cerebral structures. Evaluation of cerebral blood flow velocities (CBFV) and vascular resistance are important in assessment of cerebral circulation in neonates with hypoxic ischemic encephalopathy (HIE). The aim of this study was to evaluate the predictive value of cD-US for abnormal neurodevelopmental outcome in the neonates with HIE. A total of 90 neonates (> 32 weeks gestational age) with HIE were enrolled prospectively. All the neonates with HIE were categorized into three grades according to the Sarnat and Sarnat clinical staging system: mild HIE, moderate HIE, and severe HIE. cD-US was performed simultaneously during the first 24 h of life. Neurodevelopment outcome was assessed at 12 months of age in all the neonates. The values of CBFV and the values of index resistance (RI) correlated with the severity of HIE (p < 0.0001) and subsequent neurodevelopmental outcome (p < 0.001). We detected a significant difference in values of CBFV and in values of RI between preterm and full-term neonates (p < 0.01). The cut-off value of RI for poor neurodevelopmental outcomes was 0.81. cD-US could be very useful and safe diagnostic tool for assessing severity of HIE and subsequent adverse neurodevelopmental outcome.

Normal values of cerebral blood flow velocities in neonates

There was used color Doppler ultrasonography (cD-USI), allowing simultaneous examination of parenchymal and vascular cerebral structures. The evaluation of blood flow velocities in cerebral arteries is important in the assessment of cerebral circulation in hypoxic-ischaemic and haemorrhagic brain damage in neonates. The aim of this study was to estimate normal values of cerebral blood flow velocities (CBFV) and Doppler indices--pulsatility index (PI) and resistance index (RI)--in the anterior cerebral artery (ACA) during the first days of life in infants. CBFV, PI and RI were obtained during the first week of life with cD-US in 70 infants divided in four groups of gestational age (GA): < or =28 gestational weeks (GW); 29-32 GW; 33-36 GW; and > or =37 GW. Infants with congenital malformations, severe perinatal asphyxia, cerebral haemorrhagic lesion, DAP or severe hypotension were excluded. The mean GA of infants was 34.5 +/- 5.5 GW (range 26-40 GW) and the mean birth weight (BW) was 2540 +/- 950 g (range 750-4000 g). In the 1st group of 10 infants, < or =28 GW, the mean BW was 950 +/- 110 g and values of RI were 0.59 +/- 0.10 and PI 1.06 +/- 0.080. In the 2nd group of 20 infants, 29-32 GW, the mean BW was 1350 +/- 290 g and values of RI were 0.60 +/- 0.10 and PI 1.10 +/- 0.15. In the 3rd group of 20 infants, 33-36 GW, the mean BW was 1950 +/- 750 g and values of RI were 0.63 +/- 0.08 and PI 1.15 +/- 0.30. In the 4th group of 20 infants, > or =37 GW, the mean BW was 3540 +/- 950 g and values of RI were 0.65 +/- 0.05 and PI 1.18 +/- 0.35. Values of CBFV progressively increase with GA and BW due to progressive increase of cardiac output, blood pressure and closing of ductus arteriosus. Values of RI and PI gradually increase with GA and BW as a result of progressive maturation and opening of vascular cerebral bed with a reduction of the cerebrovascular resistance.

Cerebral blood volume, blood flow, and oxygen metabolism in cerebral ischaemia and subarachnoid haemorrhage: an in-vivo study using positron emission tomography.

A characteristic sequence of metabolic and haemodynamic changes has been shown to occur in the brain as cerebral perfusion pressure is reduced in experimental animals. Increased cerebral blood volume (CBV) occurs initially, followed by a fall in blood flow (CBF) and, finally, a fall in oxygen metabolism (CMRO2). By measuring CBV, CBF, and CMRO2 with positron emission tomography in patients with vasospasm associated with subarachnoid haemorrhage and in patients with arteriosclerotic occlusion or stenosis of extraparenchymal cerebral arteries, we have demonstrated the presence of similar changes distal to such lesions in man. These findings suggest the presence of a local decrease in perfusion pressure. This study demonstrates the utility of positron emission tomography in the assessment of cerebral circulation and metabolism in man. Measurements of regional CBV must be included for a complete assessment of the dynamics of the cerebral circulation.

Assessment of cerebral circulation (cortical blood flow) with an infrared microscope.

An infrared microscope was used for the remote detection of the surface temperature of the cerebral cortex of experimental cats. With this instrument a qualitative assessment of the circulation of the cerebral cortex can be made without interference with the integrity of the brain or vascular tissues or the reactivity of blood vessels. Although the instrument is sensitive enough to detect minor changes of cortical blood flow, its use appears limited to the detection of rapid or transient changes of cerebral circulation and is not suitable for long-term measurements of surface temperature of the brain.

Cerebral Blood Flow Studies With Sodium Pertechnetate Tc 99m and the Scintillation Camera

The use of radioisotopes in the measurement of cerebral blood flow has been extensively investigated.¹Although recent studies^2-4involving external monitoring of intravenously administered radionuclides have been of significant value in the assessment of cerebral circulation, anatomic or regional localization of vascular lesions has proven difficult. The clinical utility of the scintillation camera in the performance of dynamic clinical studies with radioisotopes^5,6and the recent use of short-lived radionuclides such as sodium pertechnetate Tc 99m in studies of regional blood flow⁷suggested the feasibility of quantitating cerebral blood flow concomitant with constant visual monitoring of the passage of^99mTc through the carotid and major cerebral arteries. Forty-four subjects without neurologic disease have been studied as controls; 15 patients with recent cerebrovascular accidents and 1 patient with an arteriovenous malformation have also been tested. <h3>Procedure</h3> We have recently modifiedthe scintillation camera employed,⁵by the use