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The first data on the effect of presence of patent foramen ovale (PFO) with high-volume right-to-left shunt (RLS) on cerebral vasomotor reactivity (CVMR) in migraineurs are herein presented. In addition, the immediate effect of air microbubbles on CVMR has been determined.Breath-holding index (BHI) and percent velocity decrease during hyperventilation (HPV) tests were performed before and after agitated saline injections in bilateral middle and posterior cerebral arteries (MCA and PCA) in 38 migraineurs (19 with aura) and 18 control subjects.Presence of PFO correlated with a significant decrease of MCA BHI (1.43 ± 0.39 vs 1.04 ± 0.67, p = 0.032) and marginal reduction of PCA BHI (1.25 ± 0.46 vs. 1.01 ± 0.39, p = 0.090) in migraineurs. After agitated saline injection, PCA BHI significantly decreased from 1.03 to 0.78 (p = 0.007) in patients with PFO, from 1.15 to 0.91 (p = 0.014) in those without PFO, and from 1.01 to 0.76 (p = 0.023) in subjects with migraine and PFO. No significant MCA BHI difference was noted soon after bubble injection.The presence of high grade RLS is associated with reduced vasodilatory CVMR in migraineurs. Further decrease of CVMR of PCA upon aerogenic microemboli passage may support the mechanism of 'facilitation with subclinical cerebral ischemia caused by microembolism', hypothesis explaining the onset of migraine.BHI: Breath-holding index; BHT: Breath Holding Test; CVMR: Cerebral vasomotor reactivity; EDV: End-diastolic velocity; HIT-6: Headache Impact Test; HPV: Hyperventilation; MCA: Middle cerebral artery; MIDAS: migraine disability Assessment score; PCA: Posterior cerebral artery; PFO: Patent foramen ovale; PI: Pulsatility index; PSV: Peak systolic velocity; RLS: Right-to-left shunt; TCD: Transcranial Doppler; Vmean: Mean velocity.

Objective: We aimed to explore the relationship between microembolic signals (MES) and cognitive impairment in patients with neurological disorders using a 30-minute MES monitoring test.Methods: We retrospectively reviewed patients who visited outpatient departments and underwent a 30-minute MES monitoring session using dual-channel transcranial doppler (TCD) at Beijing Tiantan hospital between July 2016 and December 2018. All patients completed the Montreal Cognitive Assessment (MoCA) and underwent magnetic resonance imaging (MRI). Cognitive impairment was defined as a MoCA score of less than 26. MES were identified according to the criteria of the International Consensus Group on Microembolus Detection.Results: Of the 1356 subjects who underwent MES monitoring, 159 patients (including 50 cases of MES positive and 109 cases of MES negative) had both analyzable MES monitoring recording and cognition evaluation data, of which 72 had cognitive impairment. Compared with the group with no deficits in cognitive function, the proportion of MES positive was significantly higher in patients with impaired cognitive function - that is, 47% (34/72) versus 18.4% (16/87), respectively, with p < 0.05. In multivariate logistic regression analysis, MES were independently associated with lower MoCA score (odd ratios (OR), 7.36; 95% confidence intervals (CI), 2.72-19.85, P < 0.0001).Conclusions: In this retrospective study, we found a possible correlation and relationship between MES and cognitive impairment. Further studies are required to determine whether continuous cerebral microembolization to the brain will lead to progressive cognitive impairment.

Objective: Transcranial doppler ultrasonography (TCD) is one of the few tools in the Neurological Intensive Care Unit (NICU) that allows for real-time monitoring of cerebral blood flow while also being non-invasive. This review examines the current use of TCD monitoring in the NICU. Method: We completed a literature review using Google Scholar and Pubmed. Relevant articles were included in this review. Results: The role of TCD in the NICU continues to evolve since its infancy in the 1980s. TCD use is now standard of care of for some neurological maladies. The significant advantages of TCD include convenience of use, non-invasive nature, bedside operation, high accuracy, and absence of interference from external factors such as temperature and sedatives. Conclusion: This review examines the current use of TCD monitoring in the NICU. Through review and continued development of similar non invasive technologies NICU care continues to innovate and evolve. Abbreviation: TCD: Transcranial Doppler.

Atherosclerosis is an important cause of stroke and remains a challenge for stroke prevention. Risk factors involved in atherosclerotic stroke and anterior and posterior circulation strokes (ACS and PCS, respectively) are different. The purpose of this study is to investigate differences in risk factors between intracranial and extracranial atherosclerosis (ICAS and ECAS), ACS and PCS, and ICAS/ECAS with ACS/PCS in a Chinese acute ischaemic stroke population.We analysed 551 ischaemic stroke patients who had been enrolled between August 2005 and July 2008. First, risk factors were compared between non-atherosclerosis, ICAS, ECAS, and combined ICAS and ECAS groups. ICAS and ECAS were assessed with transcranial Doppler and carotid colour Doppler ultrasound, respectively. Second, risk factors were compared between ACS and PCS groups. Stroke lesion was assessed with magnetic resonance imaging. Third, risk factors were compared in ICAS/ECAS associated with ACS/PCS.The risk factor for ICAS was high diastolic blood pressure (OR, 1.075; 95% CI, 1.016-1.138; p = 0.013), and the risk factors for ECAS were age (OR, 1.113; 95% CI, 1.046-1.183; p = 0.001) and low density lipoprotein (OR, 1.450; 95% CI, 1.087-1.935; p = 0.012). Hypertension (OR, 1.090; 95% CI, 1.001-1.109; p = 0.027) was associated with PCS. Age (OR, 1.026; 95% CI, 1.011-1.128; p = 0.003), male gender (OR, 2.278; 95% CI, 1.481-3.258; p = 0.003) and age (OR, 1.067; 95% CI, 1.013-1.123; p = 0.014), scores of NIHSS (OR, 1.069; 95% CI, 1.012-1.130; p = 0.018) were risk factors for ICAS and ECAS with ACS, respectively.Risk factors are different between ICAS and ECAS, ACS and PCS, and ICAS/ECAS with ACS/PCS. Thus, targeted strategies are needed to consider these differences to prevent, treat and manage these diseases.

Hypothermia has shown promise as a neuroprotective strategy for stroke. The use of whole body hypothermia has limited clinical utility due to many severe side effects. Selective brain cooling, or local brain hypothermia, has been previously proposed as an alternative treatment strategy. This study investigated the safety, feasibility, and efficacy of selective brain hypothermia induced by local infusion of ice-cold lactated Ringer's solution in rhesus monkeys.Eight male rhesus monkeys were used in this study. Brain temperature in the territory supplied by middle cerebral artery (MCA) was reduced by infusing 100 mL of ice-cold (0 °C) lactated Ringer's solution over 20 min via a micro-catheter placed in the proximal MCA (n = 4). Vital signs and the temperature of the brain and rectum were monitored before and after infusion. Transcranial Doppler, Magnetic resonance imaging (MRI), and digital subtraction angiography (DSA) were used to evaluate cerebral blood flow, cerebrovascular reactivity (CVR), cerebral edema, and vasospasm. Another cohort of rhesus monkeys (n = 4) were used as systemic cooling controls.Oxygen saturation, blood pressure, heart rate, and hematologic analysis of the two groups remained within the normal range after infusion. Mild cerebral hypothermia (35 °C) was achieved in 10 min (0.3 °C/min) and was maintained for 20 min in local cortex and striatum following local infusion. The average lowest cerebral temperature in the locally cooled animals was 33.9 ± 0.3 °C in the striatum following 20-min infusion. This was not observed in animals cooled by systemic infusion. The decreases in the rectal temperature for local and systemic infusion were 0.5 ± 0.2 °C and 0.5 ± 0.3 °C, respectively. Selective brain cooling did not cause any cerebral edema as determined by MRI or vasospasm in the perfused vessel based on DSA. Selective cerebral hypothermia did not significantly alter CVR.Local infusion of ice-cold lactated Ringer's solution via micro-catheter is a safe and effective method for selective cerebral hypothermia. This cooling method could potentially be developed as a new treatment in acute ischemic stroke.

We studied possible link between cerebrospinal fluid (CSF) compensation and indices describing pulsatile inflow of cerebral arterial blood.A total of 50 infusion tests performed in patients with symptoms of normal pressure hydrocephalus (NPH) were examined retrospectively. Waveforms of CSF pressure, noninvasive arterial blood pressure (ABP), and transcranial Doppler (TCD) cerebral blood flow velocity (CBFV) were used to estimate relative changes in cerebral arterial compliance (Ca) and cerebrovascular resistance (CVR). Product of Ca and CVR, called cerebral arterial time constant (τ, unit: seconds), was calculated at the baseline and plateau phase of the test and compared with CSF compensatory parameters such as resistance to CSF outflow, elasticity, slope of amplitude-pressure line, and pulse amplitude of CSF pressure.Neither of CSF compensatory parameters correlated with hemodynamic indices. However, the change in cerebral perfusion pressure (CPP) provoked change in τ (R = 0.33; P = 0.017) secondary to a change in CVR (R = 0.81; P0.0001). Changes in CVR and Ca had a reciprocal character (R = -0.64; P0.0001) with magnitude of variation in CVR (68%) prevailing over magnitude of changes in Ca (49%).Hemodynamics of pulsatile inflow of cerebral arterial blood assessed by cerebral arterial time constant is not directly linked to dynamics of CSF circulation and pressure-volume compensation but is sensitive to changes in CPP during infusion test.

To compare the diagnostic reliability of optic nerve sheath diameter (ONSD) ultrasonography with a transcranial Doppler (TCD)-based absolute intracranial pressure (ICP) value measurement method for detection of elevated ICP in neurological patients. The ONSD method has been only tested previously on neurosurgical patients.A prospective clinical study of a non-invasive ICP estimation method based on ONSD correlation with ICP and an absolute ICP value measurement method based on a two-depth TCD technology has recruited 108 neurological patients. Ninety-two of these patients have been enrolled in the final analysis of the diagnostic reliability of ONSD ultrasonography and 85 patients using the absolute ICP value measurement method. All non-invasive ICP measurements were compared with 'Gold Standard' invasive cerebrospinal fluid (CSF) pressure measurements obtained by lumbar puncture. Receiver-operating characteristic (ROC) analysis has been used to investigate the diagnostic value of these two methods.The diagnostic sensitivity, specificity, and the area under the ROC curve (AUC) of the ONSD method for detecting elevated intracranial pressure (ICP14·7 mmHg) were calculated using a cutoff point of ONSD at 5·0 mm and found to be 37·0%, 58·5%, and 0·57, respectively. The diagnostic sensitivity, specificity, and AUC for the non-invasive absolute ICP measurement method were calculated at the same ICP cutoff point of 14·7 mmHg and were determined to be 68·0%, 84·3%, and 0·87, respectively.The non-invasive ICP measurement method based on two-depth TCD technology has a better diagnostic reliability on neurological patients than the ONSD method when expressed by the sensitivity and specificity for detecting elevated ICP14·7 mmHg.

Although cognitive decline (CD) is described in antiphospholipid syndrome (APS), its physiopathology is unknown. Paradoxical embolization (PE) is related to CD in Alzheimer disease. The objective of this study was to determine whether PE plays a role in CD in APS patients through a significant right-to-left shunt (sRLS).A total of 27 patients diagnosed with APS without a history of stroke were tested for the presence of an sRLS using a contrast-enhanced transcranial Doppler (cTCD) ultrasound. Cognitive decline was assessed using the mini mental state examination (MMSE), the Montreal cognitive assessment (MoCA), and a battery of neuropsychological tests.Of the 27 patients, 19 (70%) had a non-sRLS condition (≤ 10 high-intensity transient signs [HITS] on cTCD), and 8 (30%) had an sRLS. Patients with more than 10 years of scholarship performed significantly better on both the MMSE (P = 0.048) and MoCA (P = 0.03). Individuals of the non-sRLS group with more than 10 years of scholarship had better performances on the five-point test (FPT) when compared with the sRLS group (P = 0.01).Patients without sRLS and with more years of education exhibited a better performance in cognitive tests than sRLS patients.

To investigate the existence of an association between compensatory remodeling in symptomatic middle cerebral artery atherosclerotic stenosis with high-resolution magnetic resonance imaging (HR MRI) and transcranial color Doppler monitoring of microembolic signals (MESs).A total of 36 consecutive patients with symptomatic middle cerebral artery atherosclerotic stenosis underwent MES monitoring by transcranial color Doppler and 3-T HR MRI. Proton density-weighted cross-sectional images with submillimeter voxel size were obtained. The remodeling patterns and plaque morphology of the sites of maximal luminal narrowing were analyzed in terms of their association with the MES data.Positive remodeling (PR) was found in 16 lesions (44·4%). The remodeling index was 1·11±0·05 in the PR group and 0·99±0·05 in the non-PR group (P0·0001). Compared with the non-PR group, the PR group had a greater vessel area (19·97±1·42 mm(2) versus 18·23±1·23 mm(2)) and greater wall area (16·93±1·47 mm(2) versus 14·93±1·52 mm(2); both P0·0001) at the sites of maximal luminal narrowing. Finally, MESs were observed more frequently in the PR group than in the non-PR group (62·5% versus 15·0%, P = 0·003).In patients with symptomatic middle cerebral artery atherosclerotic stenosis, MESs were observed more frequently in the PR group than in the non-PR group.

We compared autoregulation monitored with cortical laser Doppler flowmetry (LDF) and autoregulation monitored with transcranial Doppler (TCD) in the middle cerebral artery (MCA) to verify the hypothesis that, following brain trauma, cortical vessel autoregulation to intracranial hypertension is different than assessed in the MCA.Data collected from 29 head injured patients were analysed retrospectively. Arterial blood pressure (ABP), intracranial pressure (ICP), flow velocity (FV) of the MCA and cortical flux (LDF) were monitored. Indices of cortical autoregulation (Lx) and autoregulation of cerebral blood flow in the MCA (Mx) were calculated as a moving correlation coefficient between slow waves of LDF and cerebral perfusion pressure (CPP) (Lx) or FV and CPP (Mx), respectively. Intact autoregulation was indicated by negative values for Lx and Mx; disturbed autoregulation was reflected by positive values.FV and LDF showed a high coherence in the slow wave spectrum of 1-4 cycles/min (mean: 0.79 +/- 0.12), indicating that similar information regarding autoregulation is carried by both signals. Mx and Lx correlated in all patients (R=0.43, p=0.02). On average, Lx was significantly higher than Mx; the mean difference was 0.13 +/- 0.38 (p=0.032), potentially due to severe intracranial hypertension above 40 mmHg, driving CPP values below 60 mmHg.After traumatic brain injury, cortical autoregulation appears to be worse than autoregulation assessed in the MCA during rising ICP and falling CPP. When CPP is above 60 mmHg, cortical assessed autoregulation is similar to autoregulation assessed in the MCA.

Links between cerebrospinal fluid (CSF) compensation and cerebral blood flow (CBF) have been studied in many clinical scenarios. In hydrocephalus, disturbed CSF circulation seems to be a primary problem, having been linked to CBF disturbances, particularly in white matter close to surface of dilated ventricles. We studied possible correlations between cerebral haemodynamic indices using transcranial Doppler (TCD) ultrasonography and CSF compensatory dynamics assessed during infusion tests.We analysed clinical data from infusion tests performed in 34 patients suspected to suffer from normal pressure hydrocephalus, with signals including intracranial pressure (ICP), arterial blood pressure (ABP) and TCD blood flow velocity (FV). Cerebrospinal fluid compensatory parameters (including elasticity) were calculated according to a hydrodynamic model of the CSF circulation. Critical closing pressure (CrCP) was calculated with the cerebrovascular impedance methodology, while wall tension (WT) was estimated as CrCP-ICP. Closing margin (CM) was expressed as the difference between ABP and CrCP.Intracranial pressure increased during infusion from 6.7 ± 4.6 to 25.0 ± 10.5 mmHg (mean ± SD; P0.001), resulting in CrCP rising by 22.9% (P0.001) and WT decreasing by 11.3% (P = 0.005). Closing margin showed a tendency to decrease, albeit not significantly (P = 0.070) due to rising ABP (9.1%; P = 0.005). Closing margin at baseline ICP was inversely correlated to brain elasticity (R = (0.358; P = 0.038), while being significantly different from zero for the whole duration of the tests (52.8 ± 22.8 mmHg; P0.001). Neither CrCP nor WT was correlated with CSF compensatory parameters.Critical closing pressure increases and WT decreases during infusion tests. Closing margin at baseline pressure may act as an indicator of the cerebrospinal compensatory reserve.

The aim was to elucidate whether aneurysmal subarachnoid hemorrhage (SAH)-induced vasospasm induces changes of regional glucose uptake in surgically treated, asymptomatic cases.(18)FDG uptake (standardized uptake value, SUV) was analysed with PET in eight surgically treated aneurismal patients with a mean middle cerebral artery flow velocity120 cm/seconds measured with transcranial Doppler ultrasound. Data were compared with a healthy control group using Statistical Parametric Mapping (SPM99b).Six of the eight patients had no focal neurological signs. The inhomogeneous bilateral increase in SUV (p0.0001) was asymmetrical, with an almost 70% larger volume on the operated side. Reduced glucose uptake was found in the frontal and temporobasal regions of the two patients with neurological deficits (p0.0001); the affected volume was 40% larger on the operated side.SAH-induced vasospasm results in widespread increase of glucose uptake-probably reflecting increased glycolysis. This was earlier than neurological focal signs appear. Decreased glucose uptake can be detected in severe cases of vasospasm reflected by neurological deficit. Although the changes are more prominent where surgery had taken place our results suggest that not only the surgery, but also subarachnoid blood might have resulted in our findings.

Recent post-mortem studies have reported that the severity of atheromatous deposits in the circle of Willis is significantly greater, relative to non-demented (ND) elderly persons, in subjects with neuropathologically diagnosed Alzheimer's disease (AD). Additionally, the severity of intracranial atherosclerosis correlates significantly with the densities of neuritic plaques and neurofibrillary tangles. In this study, we examine the arteries of the circle of Willis by transcranial Doppler (TCD) ultrasonography.TCD was used to measure, in 25 AD patients and 30 ND elderly subjects, mean flow velocities and pulsatility indices in 16 different segments of the circle of Willis. The data were compared with and without adjustment for age, gender and systolic blood pressure.The AD patients had systematically higher pulsatility indices (p0.005) than the ND group. Incremental increases of pulsatility indices in these segments had odds ratios ranging from 1.8 to 48 for the presence of AD when adjusted for age, gender and systolic blood pressure. The left internal carotid artery siphon and the left posterior cerebral artery were the two vessels that were strongly associated with AD diagnosis. Mean flow velocities were generally lower in patients with AD but the differences did not reach the significance level.The pulsatility indices of the arteries of AD patients were generally greater than those of similarly-aged ND subjects. This difference is most likely due to increased arterial wall rigidity imposed by atherosclerotic changes. Atherosclerotic disease of intracranial arteries may be a risk factor for AD.

Clinically silent microembolic signals (MES) can be detected by transcranial Doppler sonography (TCD). There is theoretical evidence that lower ultrasound emission frequencies may lead to a higher signal intensity and thus sensitivity to detect MES. We compared a 1-MHz probe with a 2-MHz probe regarding sensitivity in the detection of MES. Moreover, embolus detection by transcranial Doppler ultrasound is very time consuming and semi-automated detection is mandatory. Therefore, we studied an on-line algorithm using the bi-gate technique and the two transmission frequencies.After defining detection thresholds ofor = 12 dB (1 MHz) andor = 10 dB (2 MHz) with eight normal subjects as MES-negative controls, taking into account natural fluctuations of the Doppler spectrum, we studied 36 patients with ischaemic events and five asymptomatic patients with incidental embolic sources. All patients subsequently underwent a 1-hour unilateral embolus detection from the middle cerebral artery (MCA) or the posterior cerebral artery (PCA), respectively, using 1 and 2 MHz for 30 minutes each in a randomized order. The software algorithm was compared with a blinded off-line analysis by an experienced observer as a gold standard.The investigator detected 198 MES (range 0-41 MES) in the recordings of 29 patients out of the 41 patients using the 1-MHz probe and 101 MES (range 0-32 MES) in the recordings of 14 patients using the 2-MHz probe (p = 0.0007). Sensitivity of the software to detect MES confirmed by the investigator was 31% using 1 MHz and 41% using 2 MHz. The positive predictive value was 6 and 30%, respectively.The sensitivity and positive predictive values of the automated algorithm to detect MES were unacceptably low for clinical practice with both frequencies. The use of 1 MHz instead of 2 MHz may, however, be useful when evaluating the recordings off-line by an experienced blinded observer.

Delayed ischemic neurological deficit (DIND) following cerebral vasospasm remains a cause for high morbidity and mortality in patients with subarachnoid hemorrhage (SAH). There is experimental and clinical evidence of positive effects of nitric oxide (NO) donors on cerebral vasospasm. We therefore analysed the effect of transdermal nitroglycerin in patients with SAH measuring transcranial Doppler velocities (TCD), cerebral blood flow (CBF) and DIND. Nitroglycerin was used in a target dose of 14 microg/kg/h. TCD assessment was performed daily. CBF measurements were done using the perfusion CT-technique. Blood pressure, volume intake and vasopressor administration, were registered. Nine patients were randomly assigned either to the nitroglycerin group (N-group) and eight patients in the control group (C-group). Mean TCD values in the extracranial portion of the internal carotid artery (ICA) were lower in the N-group (p

The relationship between changes of blood flow velocities in cerebral arteries measured by transcranial Doppler ultrasonography and aneurysm localization was investigated in a group of 165 patients after aneurysmal subarachnoid hemorrhage (SAH). Mean blood flow velocities (MFV) in the middle cerebral artery (MCA) and anterior cerebral artery (ACA) were registered. In patients with aneurysm of internal carotid artery and MCA (group A) statistically significant higher values of MFV from the 1st to the 5th day and on the 12th, 13th, 14th, 15th, and 19th day after SAH were found compared to patients with aneurysm of the anterior communicating artery, ACA, and pericallosal artery (group B). Pathological values of MFV exceeding 120 cm sec-1 in MCA were registered during 14 days in group A and during eight days in group B. Blood flow velocities in ACA were statistically significantly higher in group B on the 2nd, 7th, 9th and 11th day compared to group A. Pathological values of MFV exceeding 90 cm sec-1 in ACA were registered during nine days in both groups. MFV differences between group A and group B in 38 patients subjected to delayed surgery were not observed. The influence of aneurysm localization was observed between the 7th and 14th day after SAH. Critical MFV values for vasospasm in the MCA should be 120 cm sec-1 and in the ACA 90 cm sec-1.

Cerebral blood flow velocity (CBFV) has been shown to significantly increase during dynamic exercise (running) secondary to increases in cardiac output. Static exercise (weight-lifting) induces supraphysiological arterial pressures up to 450/380 mmHg, and thus may alter CBFV. Catastrophic brain injuries such as stroke, cerebral hemorrhage, subarachnoid hemorrhage, retinal hemorrhage and retinal detachment have been associated with weight-lifting. A recent study has shown that intra-ocular pressure (IOP), which is an indirect measure of intracranial pressure, elevates to pathophysiologic levels during weight-lifting. Recent CBFV studies instituting Valsalva have demonstrated decreases in CBFV from 21%-52%. To date, no studies have examined CBFV during maximal weight-lifting to elucidate the cerebrovascular responses to extreme pressure alterations. We recruited nine elite power athletes, including a multi-world record holder in powerlifting, for a transcranial Doppler study of middle cerebral artery blood flow velocity at rest and during maximal weight-lifting. All subjects' resting blood flow velocities were within normal ranges (mean 64.4 +/- 9.5 cm sec2). Blood flow velocities were significantly (p < 0.0001) decreased in all subjects during maximal lifting (mean 48.4 +/- 10.1 cm sec2). Linear regression analysis demonstrated a significant inverse linear relationship in the net change of blood velocities from rest to maximal lift for each subject (r = 0.8585, p < 0.001). This study demonstrates that blood flow velocities are significantly decreased during heavy resistance training. The drop in CBFV during weight-lifting was significantly less than previous Valsalva studies, which likely reveals the cardiovascular, baroreflex, and cerebrovascular system adaptations occurring in these elite power athletes.

Background and purpose: Cerebrovascular reactivity (CVR) examined by transcranial Doppler (TCD) is a useful tool for investigation of cerebrovascular reserve capacity of the normal and compromised brain. The aim of this study was to learn the acceleration of CVR as a possible additional index characterizing the process of cerebrovascular reserve recruitment and the application of this index in symptomatic and asymptomatic patients with severe unilateral carotid stenosis. Methods: Twenty-seven patients with severe unilateral internal carotid artery (ICA) stenosis were included in the study. TCD examination with acetazolamide test was used for the measurement of cerebrovascular reactivity before and after CEA. The acceleration (cm/s2) of CVR was calculated as ratio of ΔV before and after acetazolamide injection related to time of the velocity change. Results: The acceleration of CVR in patients with severe unilateral ICA stenosis before CEA was 0.03 ± 0.03 cm/s2 and after the operation was 0.07 ± 0...

Supraventricular and ventricular tachyarrhythmia are established causes of syncope. We investigated the mean blood flow velocities (Vmean) of the middle cerebral arteries (MCA) during routine cardiac electrophysiologic studies in patients with supraventricular and ventricular tachyarrhythmias in order to evaluate the changes in cerebral hemodynamics associated with pre-syncopal and syncopal states. Thirty-two patients with a history of supraventricular (n = 14) or ventricular (n = 18) tachyarrhythmias were investigated in the nonsedated, post-absorptive state in supine position. Vmean was assessed in both MCAs by means of transcranial Doppler under resting conditions, during atrial and ventricular pacing at constant rates (n = 28) and during induction of tachyarrhythmia (n = 4). Mean arterial blood pressure (MABP) and heart rate were also recorded. Seven patients suffered pre-syncope at a heart rate of 187 +/- 45 bpm (mean +/- SD) with an average drop of 44% in the Vmean MCA, and statistically insignificant changes in MABP. Five patients suffered syncope during tachyarrhythmia (mean heart rate 283 +/- 42 bpm) with a reduction of 69% in the Vmean MCA. MABP could be assessed in two of those patients and showed a drop of 15 and 43 mmHg, respectively. During tachyarrhythmia pre-syncope and syncope are associated with an average reduction in Vmean MCA by 44% and 69%, respectively. The decrease in MCA blood flow velocity is a more important predictive factor for the development of pre-syncope and syncope than the MABP.

To evaluate prospectively the diagnostic accuracy of transcranial doppler (TCD) as an additional screening tool for intracranial arterial steno-occlusive disease against computed tomography angiography (CTA) in patients with acute ischemic stroke (AIS) if both are performed in a short time interval.Between July 2011 and May 2012, 128 patients who were hospitalized within 24 hours of symptom onset and fulfilled the criteria for the clinical diagnosis of AIS were enrolled. Bedside detection of TCD was accomplished immediately after admission. High-resolution brain CTA was performed within 3 hours after the completion of TCD and the images were interpreted by a neuroradiologist blinded to TCD findings. The accuracy parameters of TCD against CTA were calculated after computation of true-positive, false-positive, true negative, and false-negative values.Among the 128 patients, there were 68 males and 60 females, aged 61.4 ± 17.5 years. The mean time interval between the detection of TCD and CTA was 89.7 (77.8) minutes. In 65% of patients, both examinations were performed with less than a half-hour interval between them. The diagnostic accuracy of TCD for different arteries showed slight distinction. Transcranial doppler demonstrated the most accurate diagnosis for middle cerebral artery (MCA), where TCD showed 35 true-positive, 0 false-negative, 1 false-positive, and 92 true-negative studies compared with CTA. Furthermore, elevated MCA velocities on TCD correlated well with the severity of intracranial stenosis detected on CTA. Vertebral artery (VA) is one of the arteries with the lowest sensitivity for TCD diagnosis (sensitivity 63.4%, specificity 96.5%, positive predictive value (PPV) 89.6%, negative predictive value (NPV) 84.8%, and accuracy 85.9%). In 20 cases (15.6%), TCD showed findings complementary to CTA (real-time embolization, collateral flow patterns, and steal phenomenon).Transcranial doppler shows high diagnostic accuracy against CTA if both are performed in a short time interval in evaluating intracranial arterial stenosis/occlusion in patients with AIS, especially for MCA obstruction. Transcranial doppler can also provide additional real-time dynamic findings complementary to the information provided by CTA. This can result in changes in the management in some of these patients.

The associations between cognitive impairment following the initial onset of transient ischaemic attack (TIA) and the parameters of altered cerebral blood flow and high-sensitivity C-reactive protein (HsCRP) level are unclear.A total of 97 first-time TIA patients aged 69.94 ± 4.02 years (38-75 years; M:F, 50:47) hospitalized between March 2010 and July 2011 were compared to 100 healthy control patients aged 66.56 ± 12.15 years (45-80 years; M:F, 60:40). Cognitive function was quantified by Montreal Cognitive Assessment (MoCA). Intracranial blood flow was measured using transcranial Doppler ultrasound, and HsCRP levels were assessed using the Spearman correlation coefficient. Relationships between both values and MoCA scores were examined.Transient ischaemic attack patients exhibited declined cognitive function manifested as impaired verbal fluency (97.93%), memory recall (91.75%), abstraction (84.53%), and visuospatial/executive abilities (79.38%). To a lesser degree, TIA patients also evidenced abnormalities in attention (50.52%), naming (20.62%), and orientation (20.62%). Furthermore, MoCA scores significantly correlated with high HsCRP levels and low vascular systolic peak velocities (P0.001). Vascular systolic peak velocities were high in nine patients (9.23%) and low in 57 patients (58.76%). Thus, cognitive impairment was closely related to HsCRP levels and intracranial blood flow velocities.Post-TIA cognitive impairment may result from atherosclerosis and reduced blood flow to the brain. Cognitive impairment, transcranial Doppler-visualized changes, and elevated HsCRP levels are important diagnostic indicators of TIA. Markers provided by cognitive evaluation of TIA patients following the initial onset of TIA may allow clinicians to better predict and prevent adverse vascular events.

Cerebral perfusion pressure (CPP)-oriented therapy and the Lund concept lie on opposite ends of the CPP scale, in the management of head injury. Optimization of CPP by monitoring cerebral vascular pressure reactivity is an alternative approach that may reconcile these two divergent approaches, preventing both injurious hypotension and hypertension with an individualized CPP target.Indices describing cerebral vascular reactivity or cerebral blood flow autoregulation, derived from intracranial pressure, near-infrared spectroscopy, or transcranial Doppler are reviewed in this manuscript.Indices of cerebrovascular reactivity and autoregulation typically converge to a U-shape curve when viewed as a function of CPP, with the best reactivity metrics indicating optimal CPP. In a retrospective study of prospectively collected data from head-injured patients, Steiner et al. demonstrated that a greater distance between averaged over total monitoring time-CPP and optimal CPP, correlated with unfavourable outcome. A recent study of 300 head-injured patients (2003-2009) showed that hypotension below optimal CPP was associated with greater mortality rate, while hypertension above optimal CPP was associated with an increase in severe disability.Pilot studies indicating feasibility of autoregulation-oriented CPP optimization have been performed in adult and paediatric traumatic brain injury, aneurysmal subarachnoid haemorrhage, and in patients undergoing cardiothoracic surgery. It remains to be prospectively demonstrated whether optimal CPP management is able to improve outcome.

Three patients, two women and one man, aged 56-70 year (mean 59 years) with modest neurological deficits and bilateral occlusion of the common carotid arteries initially identified by duplex scanning and angiography were followed by repeated clinical and transcranial Doppler examination (TCD) over 6.5 years. Vasomotor reactivity (VMR) was tested by combined examination of TCD and xenon-133 cerebral blood flow (CBF) before and after intravenous administration of 1 g acetazolamide. At follow-up CBF was measured using single photon emission computerised tomography (SPECT). In two patients mean velocities in the middle cerebral artery (MCA) were within the normal range at repetitive examinations with good VMR ranging 30-111%, whereas CBF was reduced in MCA territories ranging 29-36 ml 100 g(-1) min(-1), but increasing 44-69% after acetazolamide, indicating good VMR. These 2 cases had anterograde flow in the ophthalmic artery and siphon. The third patient had very low MCA mean velocities of 21-27 cm sec(-1), increasing 26-33% after acetazolamide. This patient had retrograde flow in the ophthalmic artery and siphon connected with bilateral prolonged episodes of amaurosis fugax and transient ischemic attacks. In all three patients the posterior cerebral arteries were major supplying collaterals having high mean velocities of about 100 cm sec(-1) and high velocities in the basilar arteries of 85 cm sec(-1) as well. During follow up no patient had a new stroke, but all experienced orthostatic dizziness and chronic fatigue.

Application of transcranial Doppler ultrasonographyoto asymptomatic prosthetic heart valve patients can result in the detection of transient high intensity signals, similar to those induced by the ...

In order to compare the results of nonlinear analysis of hemodynamically compromised and noncompromised cerebral circulations we measured consecutive transcranial Doppler (TCD) waveforms of fourteen patients with a unilateral or bilateral occlusion of the internal carotid artery. The cerebral vasomotor reactivity (VMR) to acetazolamide in both middle cerebral artery (MCA) territories was established by using TCD. Conventional TCD data and nonlinear TCD analysis of data were compared. Nonlinear analysis of the TCD time series suggested dynamical chaos based on the fractal dimension of the TCD curve and the positive Lyapunov exponents in the compromised and noncompromised MCA territories. In the areas with the compromised circulation the positive Lyapunov exponents were significantly lower compared to the noncompromised side and in some cases with a negative VMR, the Lyapunov exponent was almost zero. The latter is suggestive for periodic behavior of the impaired cerebral circulation instead of the dynamical chaos which is found under normal conditions. The TCD time series of a hemodynamic compromised cerebral territory not only shows phenomena related to a decreased perfusion pressure (such as a 'damped waveform') but also phenomena which are related to a more prominent periodicity. We speculate that conventional and nonlinear TCD analysis could be used to determine the VMR.

Seventeen patients, 14 males and 3 females, mean age 64 years (range 45-77 years) with longstanding unilateral occlusion of the internal carotid artery and minimal neurological deficit, were evaluated in order to find criteria for potential benefit of extracranial-intracranial by-pass surgery. 3-D transcranial Doppler was used for estimation of mean velocities and pulsatility index in the middle cerebral artery, anterior cerebral artery and posterior cerebral artery before and after iv injection of 1 g acetazolamide. The anterior cerebral artery was the supplying vessel to the occluded side in 16 patients and mean velocities were significantly (p < 0.001) faster on the occluded (59.3 +/- 14.5 cm sec-1) and nonoccluded (91.6 +/- 29.6 cm sec-1, p < 0.05)) side than those found in the middle cerebral artery (39.2 +/- 13.7 and 50.9 +/- 8.5 cm sec-1). In two patients a decrease of mean velocity after acetazolamide was noted in middle cerebral artery indicating 'steal' effect. In another 4 patients, poor vasomotor response was seen with less than 11% of mean velocity increase in the middle cerebral artery. Differences between posterior cerebral artery on the occluded and nonoccluded side were insignificant as well as those between middle and posterior on the occluded side. Resting values of pulsatility index differed significantly (p < 0.01) only between anterior and posterior cerebral artery on the nonoccluded side.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracranial artery stenosis may be the most frequent cause of ischemic stroke in the world. Early detection of asymptomatic intracranial artery stenosis may allow for therapeutic intervention. Most elements of the Framingham stroke risk profile (FSRP) are also risk factors for intracranial artery stenosis. Thus, the FSRP might play a role in detecting asymptomatic intracranial artery stenosis.To investigate the relationship between the FSRP and asymptomatic intracranial artery stenosis.A sample of 5852 subjects (age40 years) was selected from the KaiLuan study. All participants received transcranial Doppler ultrasound examinations to detect the presence and quantify the severity of intracranial arterial stenosis. Demographic and clinical variables were investigated at the time of examination. Binary logistic regression analyses was performed to determine the odds ratio of FSRP components to asymptomatic intracranial stenosis before and after adjusted for gender, body mass index (BMI), and total cholesterol (TC).The subjects with intracranial artery stenosis were older than those without (68·2 versus 64·9), and the systolic blood pressure was higher in those with intracranial artery stenosis (146·86 versus 136·39). Among intracranial artery stenosis subjects, 77·5% had hypertension, 26·1% had diabetes, 8·9% had left ventricular hypertrophy, and 4·8% had atrial fibrillation. Logistic regression analyses revealed that age, systolic blood pressure, diabetes, atrial fibrillation, and left ventricular hypertrophy were risk factors for intracranial artery stenosis. The incidence of asymptomatic intracranial artery stenosis correlated with increasing FSRP scores. The odds ratios of intracranial artery stenosis from the lowest to the highest FSRP quartiles were as follows: 1 (reference group), 1·77 (95% CI: 1·23-2·56), 2·84 (95% CI: 2·02-3·98), 5·65 (95% CI: 4·03-7·93).FSRP plays an important role in detecting asymptomatic intracranial artery stenosis.

In order to estimate whether or not the variability of a timeseries of transcranial Doppler (TCD) waveforms is the result of a random or a deterministic process the following study was designed. From eight normal volunteers the middle cerebral artery blood flow velocities were measured for 50 sec and the maximum blood flow velocities (or waveforms) were analysed. From these waveforms socalled attractors were reconstructed and shown in a two dimensional phase portrait. The attractor of the TCD timeseries shows the entire range of states the cardiovascular system can display. The geometric structure of the attractor can be estimated by calculation of the correlation dimension D2. The correlation dimension D2 shows that the time evolution of the TCD timeseries is essentially nonperiodic and can be characterized by low dimensional chaos. It has been shown that the D2 value during hypocapnia has a significant higher value compared to the D2 values during normocapnia. The biological and clinical significance of these observations are outlined.

Intracranial pressure (ICP) was monitored continuously for one night in 36 patients with suspected symptomatic normal pressure hydrocephalus (NPH) to identify patients who might benefit from subsequent shunting. In 33 of these patients middle cerebral artery (MCA) blood flow velocity by means of transcranial Doppler sonography (TCD) and ICP were recorded simultaneously. ICP B-waves always paralleled changes in the TCD signal (TCD B-wave equivalents). The relative frequency of ICP B-waves was predictable by TCD, albeit slightly underestimated due to a generally lower relative amplitude of the TCD B-wave equivalents. However, the same TCD B-wave equivalent amplitude could be accompanied by quite different ICP changes in different patients. Considering the baseline values in the absence of pressure waves, there was no significant relationship between ICP and TCD resistance index (Pourcelot) in different patients. Raising ICP by injection of 10 ml saline into the ventricle, however was accompanied by an increased TCD resistance index in the individual patient. As the relative frequency of B-wave activity is assumed to be an indicator for shunt responsiveness, continuous TCD monitoring can be used as a screening procedure to detect the presence and the relative frequency of B-wave activity in patients with suspected NPH. However, since neither the absolute ICP nor the amplitude of spontaneous oscillations can be predicted, TCD monitoring is not suitable to replace ICP monitoring.

Continuous transcranial Doppler ultrasound (TCD) monitoring of the middle cerebral artery (ACM) is a potent new technique in detecting thromboembolic and haemodynamic complications in interventional neuroradiology. An illustrative case is reported of a 6-year-old boy suffering from right-sided rhabdomyosarcoma of the neck in which permanent balloon occlusion of the right ACI was attempted. During the procedure, repeated severe thromboembolic events with temporary occlusion of the M1 segment of the ACM could be detected by TCD monitoring. Complications could then be avoided by cessation of the undertaking and lysis therapy with urokinase. The report concludes that TCD monitoring during endovascular treatment provides important insight into the thromboembolic pathophysiology, guides management strategies, helps in the avoidance of devastating events and should be performed during all interventional procedures, as well as during balloon occlusion of the ACL [Neurol Res 1994; 16: 137-140]

The cerebrovascular time constant (τ) describes the time to establish a change in cerebral blood volume after a step transient in arterial blood pressure (ABP). We studied the relationship between τ, ABP, intracranial pressure (ICP), and end-tidal carbon dioxide concentration (EtCO2).Recordings from 46 anaesthetized, paralysed and ventilated New Zealand rabbits were analysed retrospectively. ABP was directly monitored in the femoral artery, transcranial Doppler (TCD) cerebral blood flow velocity (CBFV) from the basilar artery, and ICP using an intraparenchymal sensor. In nine animals end-tidal CO2 (EtCO2) was monitored continuously. ABP was decreased with injection of trimetophan (n = 11) or haemorrhage (n = 6) and increased by boluses of dopamine (n = 11). ICP was increased by infusion of normal saline into the lumbar cerebrospinal fluid space (n = 9). Changes in cerebral compliance (C(a)) were estimated as a ratio of the pulse amplitude of the cerebral arterial blood volume (CBV) and the pulse amplitude of ABP. Changes in cerebrovascular resistance (CVR) were expressed as mean ABP or cerebral perfusion pressure (CPP) divided by mean CBFV. Time constant τ was calculated as the product of CVR and C(a).The time constant changed inversely to the direction of the change in ABP (during arterial hypo- and hypertension) and CPP (during intracranial hypertension). C(a) increased with decreasing CPP, while CVR decreased. During a decrease in CPP, changes in C(a) exceeded changes in CVR. In contrast, during hypercapnia, the decrease in CVR was more pronounced than the increase in C(a), resulting in a decrease in τ.Cerebrovascular time constant τ is modulated by ABP, ICP, and EtCO2.

To investigate the characteristics of transcranial Doppler variables in the acute stage of intracerebral hemorrhage (ICH) and its relationship with 14-day death and outcomes at 90 day after onset.Ninety first-time supratentorial nontraumatic ICH patients were prospectively included. Computed tomography and transcranial Doppler examinations were performed on the first, third, seventh, and fourteenth day after onset. Transcranial Doppler variables were obtained from bilateral middle cerebral arteries. The relationship between ICH outcome and the following variables were analyzed: systolic (V(s)), diastolic (V(d)), mean (V(m)) velocities, and pulsatiliy index (PI) from affected and unaffected hemispheres.Fourteen (15.6%) patients died within 14 days after onset of ICH. The stepwise logistic regression analyses proved presence of intraventricular hemorrhage (OR: 11.91; 95%CI: 1.62-87.42) and PI from unaffected hemisphere (OR: 1.64; 95%CI: 1.19-2.25) to be independent predictors of 14-day death. Forty-eight of the 90 ICH patients performed the transcranial Doppler monitoring at all four time points. V(m) from both hemispheres decreased gradually within 14 days after onset. Among the 48 patients, 22 patients were dependent (modified Rankin Scale ≥ 3) at 90 days after onset. Compared with patients who were independent at 90 days, V(d) (F = 4.98, P = 0.03) and V(m) (F = 7.30, P0.01) from unaffected hemisphere were significantly lower, while the PI was significantly higher in patients who were dependent (F = 9.84, P0.01).Presence of intraventricular hemorrhage and PI from unaffected hemisphere proved to be independent predictors of 14-day death. Sustained persistent decreases in V(d) and V(m) and increases in PI from the unaffected hemisphere during the acute stage may be related with dependency at 90 days.

To examine cerebrovascular reactivity in patients after subarachnoid haemorrhage (SAH) during long-term follow-up, using Acetazolamide test and transcranial Doppler (TCD) monitoring of blood flow velocities (BFVs), to compare of CO(2) reactivity between patients after SAH treated with three different methods: surgical (clipping), endovasculary (coiling) and conservative.The study was performed in a group of 24 patients treated for SAH. Cerebrovascular reactivity (CVR) has been evaluated after intravenous administration of 1000 mg of Acetazolamide. Studied patients were divided into three groups: group I (n = 10) treated with clipping, group II (n = 8) treated with coiling and group III (n = 6)--patients with negative angiography treated conservatively.Results of this study have shown that: (1) BFVs were normal in cerebral arteries and did not differ between right and left head sides, (2) CVR was normal in all studied patients, (3) method of aneurysm treatment as well as its localization had no influence on BFV and CVR, and (4) occurrence of vasospasm in early days after SAH did not result in permanent disturbances of CO(2) arterial reactivity.BFV values in cerebral arteries were in normal range and did not differ on the left and right head sides. CVR was normal in all examinated patients. A method of the ruptured aneurysm treatment and its localization had no influence on CBFV and CRV. Vasospasm in early period after SAH did not provoke a persistent impairment of CO(2) reactivity.

Fifteen patients with symptoms of cerebral ischaemia and angiographically confirmed unilateral stenoses or occlusions of the extracranial internal carotid artery (ICA) and 20 controls were studied by a 2 MHz transcranial Doppler (TCD) at rest and after stimulation with 1 g acetazolamide i.v., a cerebral vasodilator. In addition, the patients underwent 99mTc-HM-PAO-Spect measurement of regional cerebral blood flow (rCBF) at rest and after stimulation with 1 g acetazolamide. In 10 patients with ICA stenoses greater than 80% or occlusions, time-mean velocity (Vmean) increase and pulsatility index (PI) decrease in the postobstructive middle cerebral artery (MCA) as well as the increase of the ipsilateral rCBF were reduced in comparison with the contralateral side. The remaining 5 patients showed a normal Vmean increase and PI decrease in TCD.

Cerebral blood flow (CBF) and the cerebral vasoreactivity was measured in patients with cerebrovascular disease and longstanding occlusion of the common carotid artery (CCA). In addition, regional CBF was correlated with transcranial doppler (TCD) measurements at baseline and during 6% CO2 inhalation and after intravenous administration of 1 g of acetazolamide. Twelve patients with a mean age of 62 years (range 45 to 71 years) were included, and the data compared to age-matched healthy controls. CBF was measured by intravenous injection of xenon-133 and SPECT (Tomomatic 564). TCD of the middle cerebral artery (MCA) was done by EME TC-64B. A very low global CBF value of 28 +/- 5 (SD) ml 100 g-1 min-1 was found at baseline as compared to 55 +/- 5 ml 100 g-1 min-1 in the normal controls. During 6% CO2-inhalation and after acetazolamide administration, CBF increased by 58 +/- 24% and 51 +/- 21%, respectively, indicating substantial collateral supply. Correlative analysis of CBF in the MCA territory and TCD in the MCA showed statistical significance only for the pooled data, i.e. compiling the data obtained during baseline and the two vasodilatory tests, and then only for the mean and peak TCD velocity (e.g. r = 0.59, p less than 0.002, n = 35, mean velocity, right side). We conclude that TCD measurements do not predict regional CBF in patients with CCA occlusion. The study emphasizes that these two methods yield supplementary information, with TCD measurements providing information of the circle of Willis and CBF studies of the flow distribution.

Microembolic signals (MES) have been found in about 10% of patients with systemic lupus erythematosus (SLE), and have been associated with neuropsychiatric manifestations (NPSLE), including cerebrovascular damage.To determine the frequency of MES in patients with SLE, previous and further risk of neuropsychiatric manifestations.One hundred and nine consecutive patients with previous diagnosis of SLE and without acute neurological manifestations were evaluated clinically and by transcranial Doppler monitoring (1 hour) from November 2002 to March 2003. The baseline characteristics and outcomes were compared between patients with and without MES. Patients were followed during a mean time of 4.5 years, to detect the appearance of NPSLE, including stroke and transient ischemic attacks.MES were detected in 16 patients (14.7%; range: 3-64/h); at baseline, previous neuropsychiatric manifestations were more frequent in patients with MES: 12/16 (75%) versus 46/92 (50%) (p=0.064), especially for cognitive dysfunction (p=0.036). Antiphospholipid syndrome and cardiovascular risk factors did not differ between groups at baseline and follow-up, neither the proportion of patients on antiplatelet agents. At follow-up, two patients from the MES positive group and six from the MES negative group developed a new neuropsychiatric manifestation (p=not significant).This study supports an association of MES and a history of NPSLE, especially cognitive dysfunction. MES were not associated with an increased risk of cerebral ischemia and other neurological manifestations at follow-up.

Cerebral vasospasm is one of the major complications of subarachnoid hemorrhage. The delayed occurrence of this complication allows for preventive management and early therapeutic interventions. Yet, accurate and timely diagnosis remains challenging and therapeutic options are rather limited. This review discusses new developments in the diagnosis and medical management of cerebral vasospasm made possible by technological advances and growing understanding of the complex pathophysiology of this disorder. CT protocols including CT perfusion and MRI with diffusion and perfusion sequences are increasingly employed in the evaluation of patients with suspected vasospasm. These radiological studies can add important information to that provided by transcranial Doppler and conventional angiography. Nimodipine for the prevention of delayed functional sequelae and hemodynamic augmentation therapy for the treatment of symptomatic vasospasm remains the mainstay of medical management. Novel strategies under investigation include the use of endothelin receptor antagonists, magnesium sulphate and statins. The value of albumin is being formally studied in an ongoing trial. Interventions to enhance nitric oxide may prove viable in the near future.