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For patients with symptomatic unilateral internal carotid artery (ICA) occlusion, impaired cerebrovascular reactivity (CVR) indicates increased stroke risk. Here, the role of collateral activation remains a matter of debate, whereas angio-anatomical collateral abundancy does not necessarily imply sufficient compensatory flow provided. We aimed to further elucidate the role of collateral activation in the presence of impaired CVR. From a prospective database, 62 patients with symptomatic unilateral ICA occlusion underwent blood oxygenation-level dependent (BOLD) fMRI CVR imaging and a transcranial Doppler (TCD) investigation for primary and secondary collateral activation. Descriptive statistic and multivariate analysis were used to evaluate the relationship between BOLD-CVR values and collateral activation. Patients with activated secondary collaterals exhibited more impaired BOLD-CVR values of the ipsilateral hemisphere (p = 0.02). Specifically, activation of leptomeningeal collaterals showed severely impaired ipsilateral hemisphere BOLD-CVR values when compared to activation of ophthalmic collaterals (0.05 ± 0.09 vs. 0.12 ± 0.04, p = 0.005). Moreover, the prediction analysis showed leptomeningeal collateral activation as a strong independent predictor for ipsilateral hemispheric BOLD-CVR. In our study, ipsilateral leptomeningeal collateral activation is the sole collateral pathway associated with severely impaired BOLD-CVR in patients with symptomatic unilateral ICA occlusion.

Background Cerebral stroke is a major source of mortality and morbidity. Duplex ultrasonography is used to evaluate carotid and cerebral arteries. The objectives of this work are to study the correlation between carotid duplex parameters with risk factors of ischemic stroke and evaluate duplex parameter as prognostic tool of ischemic stroke. Methods The study was conducted on 100 patients presented by acute ischemic stroke submitted to history taking, medical, and neurological examination. Neurological deficit was assessed by National Institute of Health Stroke Scale (NIHSS); the functional state of the patients was assessed by modified Rankin scale (mRS). Brain CT and/or MRI, routine laboratory investigations, extracranial, and transcranial duplex (TCD) were done. Results The end diastolic velocities (EDVs) and peak systolic velocities (PSVs) of common carotid arteries (CCA) were significantly decreased in smokers and hypertensive (P Conclusion Patients who have risk factors of stroke should be evaluated with duplex ultrasonography. Duplex parameters can give informative data about prognosis and outcome.

Background Idiopathic intracranial hypertension (IIH) is a disorder of increased intracranial pressure without a clear cause and can have serious visual effects. Previous research work suggests that transcranial Doppler measurements of pulsatility index correlate accurately with elevated intracranial pressure. Objective To assess the cerebrovascular hemodynamic changes in patients with IIH using transcranial Doppler before and after lumbar puncture and CSF withdrawal. Methods An interventional study conducted on 40 patients (31 females and 9 males) fulfilling the modified Dandy criteria for diagnosis of idiopathic intracranial hypertension, MRI brain, and MRV was done to the patients. Lumbar puncture was done for all included patients to measure intracranial pressure and CSF withdrawal. Transcranial Doppler was performed for all included before and after lumbar puncture and CSF withdrawal and the following parameters were measured: peak systolic velocity (PSV), end diastolic velocity (EDV), resistivity index (RI), and pulsatility index (PI). Results Significant relation was found between grades of papilledema and PSV, RI, and PI (p value 0.012, 0.025, 0.016) but no significant relation was found between grades of papilledema and EDV (0.102). Significant changes occurred in parameters of TCD pre- and post-CSF withdrawal including PSV, EDV, and PI (p value 0.001, 0.015, 0.019) denoting a significant change in cerebral hemodynamics after CSF withdrawal which denotes a decrease in intracranial pressure. Conclusion Increased intracranial pressure significantly affects cerebral blood flow. A normalization of transcranial Doppler parameters occurs following lowering of intracranial pressure through lumbar puncture and CSF withdrawal.

Objective: The objective of this study was to evaluate the effect of blood pressure (BP) management with transcranial Doppler (TCD) guidance in patients with large-vessel occlusion in the anterior circulation after endovascular thrombectomy (EVT) on the long-term prognosis.Methods: This was a prospective study; 232 patients were nonrandomized assigned to TCD-guided BP management (TBM) group or non-TCD-guided BP management (NBM) group. In the TBM group, BP was controlled according to TCD showing cerebral blood flow fluctuation. In the NBM group, BP was controlled according to the guidelines. The primary endpoint was a modified Rankin scale (mRS) score of 2 or lower at 90 days. The safety outcomes were the rates of symptomatic or any intracerebral hemorrhage (ICH) and mortality at 90 days.Results: One hundred sixty-three patients were assigned to the TBM group, and 69 were assigned to the NBM group. In the propensity score-matched cohort (65 matches in both groups), there was significant difference in the proportion of participants with mRS 0–2 at 90 days according to BP management (adjusted odds ratio 3.34, 95% CI 1.36 to 8.22). There was no difference in the rates of symptomatic or any ICH and mortality between two groups. In inverse probability-weighted regression adjustment analysis, mortality decreased significantly in the TBM group than in the NBM group (adjusted odds ratio 0.86, 95% CI 0.76–0.99, p = 0.03).Conclusion: In patients with acute ischemic stroke from large-vessel occlusion in the anterior circulation, BP management under TCD was superior to NBM in improving the clinical outcomes at 90 days.Clinical Trial Registration: (URL: https://www.chictr.org.cn/showproj.aspx?proj=55484; Identifier: ChiCTR2000034443.

Introduction: Emergency care delivery to patients in remote and rural areas is limited by diagnostic restrictions and long transport times to major centres of care. People with suspected acute stroke living long distances from a hospital are unlikely to receive time-critical reperfusion therapy for these reasons. Basic brain imaging assessing blood flow in the major intracranial arteries could facilitate such care in remote settings. A 3-hour training package for novice transcranial ultrasound users has been piloted on a small group of volunteers to investigate whether they could acquire transcranial ultrasound images and video clips to potentially allow remote interpretation and optimise pre-hospital management of acute stroke. Methods: A pilot training project was set up in a university setting in Inverness, Scotland. Volunteer clinicians and students of nursing or medicine with no practical experience in transcranial ultrasound were recruited. Participants received three 1-hour training sessions combining theoretical aspects and hands-on practice on healthy volunteers provided by a qualified neurologist with more than 2 years of experience in transcranial ultrasound. Transcranial greyscale and colour-coded duplex sonography was performed to visualise midline structures and major intracranial vessels, and to measure blood flow velocity in the middle cerebral artery, followed by an unsupervised assessment. Qualitative analysis of the anonymised feedback from participants on the training experience and its potential application was also performed. Results: A total of 11 volunteers were recruited in the current pilot study. The average time to complete transcranial ultrasound assessment was approximately 40 minutes. The brain midline and cerebral peduncles were correctly labelled by 64% (7/11) and 91% (10/11) of volunteers, respectively. Participants demonstrated a good performance in detecting major intracranial vessels. The correct labelling rate for the middle cerebral artery was 73% (8/11), and 64% (7/11) for the anterior and posterior cerebral arteries. There was agreement between the trainer and the participants on rating the quality of scans as assessed using a visual analogue scale. All participants gave positive feedback on the provided training and time allocated for each session. Generally, volunteers thought that operating the ultrasound machine and the probe simultaneously was difficult. It was also suggested that further follow-up training, with possible supervision, would be useful to retain the acquired skills. Conclusions: Transcranial ultrasound scans of a quality to allow expert interpretation can be acquired by inexperienced transcranial ultrasound operators after receiving a brief training. This could potentially be used by medical staff working in remote and rural areas to facilitate acute care for stroke patients, but further work with a larger sample is needed.

Introduction: Sensitisation of the nervous system in a patient with migraine is supposed to be associated with calcitonin gene-related peptide (CGRP) activity. Therefore, the vascular response to human αCGRP (hαCGRP) could be a surrogate marker for the sensitization. We hypothesize that vascular response to hαCGRP is augmented in a patient with migraine.Methods: Twenty healthy subjects and 20 patients with migraine participated in our study. TCD was used to monitor mean arterial velocity in the middle cerebral artery (vm MCA). Simultaneously, end-tidal CO2 (Et-CO2), mean arterial pressure (MAP), and heart rate (HR) were measured. The reconstruction of the signals was made for basal conditions, during and after CGRP infusion which were compared using statistics.Results: In both groups, we found significant decrease between measurement points of vm MCA and Et-CO2 during and after hαCGRP infusion. MAP did not show significant trends during the infusion, but it was significantly increased after the infusion in migraine patients only. Responses to hαCGRP, defined as differences between two measurement points, were significantly higher for vm MCA and Et-CO2 in patients with migraine. A significant difference between groups was found in MAP response. Significant relationships were found between migraine and vm MCA, Et-CO2, and MAP.Conclusion: In patients with migraine, vm MCA responses to hαCGRP are significantly higher and are associated with CGRP-induced headache which indicates that patients with migraine are more prone to sensitization.

Background and Purpose: Intracranial atherosclerosis has gained increasing attention due to the high risk of recurrent clinical or subclinical ischemic events, while the relationship between low-density lipoprotein cholesterol (LDL-C) measured at a single time point and intracranial atherosclerotic stenosis (ICAS) is inconsistent. This study aims to assess the association between cumulative exposure to increased LDL-C and the prevalence of asymptomatic ICAS.Methods: The Asymptomatic Polyvascular Abnormalities Community study was investigated on the epidemiology of asymptomatic polyvascular abnormalities in Chinese adults. In this study, we included 4,523 participants with LDL-C measured at 3 examinations in 2006, 2008, and 2010. Cumulative exposure to increased LDL-C was calculated as following: LDL-C burden2006−2008 = [(LDL-C2006-1.8) + (LDL-C2008-1.8)]/2 * time2006−2008; LDL-C burden = LDL-C burden2006−2008 + LDL-C burden2008−2010. Transcranial doppler ultrasonography was performed in 2010 to detecting the ICAS.Results: Of the 4,347 patients, 13.3% (580/4,347) were diagnosed with ICAS. In univariate analysis, the association between LDL-C burden and ICAS prevalence was significant, the odds ratios (95% confidence interval) from the lowest to the highest quartile were 1 (reference), 1.30 (0.99–1.70), 1.32 (1.01–1.73), and 2.14 (1.66–2.75), respectively (P < 0.05). After adjustment for potential confounding factors, the same result was reached.Conclusions: Cumulative exposure to increased LDL-C is concentration-dependently associated with increased prevalence of asymptomatic ICAS, especially in those under the age of 65 y or free of hypertension, diabetes mellitus, and hyperlipidemia.

Introduction Aging is associated with impaired cerebrovascular blood flow and function, attributed to reduced vasodilatory capacity of the cerebrovascular network. Older adults may also have an impaired relationship between changes in blood pressure and cerebral blood flow; however, previous reports conflict. This study aimed to compare the blood pressure and cerebral blood flow responses to both repeated and sustained stand‐to‐sit transitions in young and older adults, and to assess the relationship with cerebrovascular reactivity. Methods In 20 young (age: 24 ± 4 years) and 20 older (age: 71 ± 7 years) adults we compared middle cerebral artery flow velocity (MCAv), end‐tidal partial pressure of carbon dioxide (PETCO2), and blood pressure (mean arterial blood pressure [MAP]) during repeated stand‐to‐sit (10 s standing and 10 s sitting) and sustained stand‐to‐sit (3 min standing followed by 2 min sitting) transitions. Cerebrovascular reactivity to changes in carbon dioxide levels was assessed using a repeated breath‐hold test. Results The % change in MCAv per % change in MAP (%∆MCAv/%∆MAP) was higher in the older adults than in the young adults during repeated stand‐to‐sit transitions. During the sustained protocol the %∆MCAv/%∆MAP response was similar in both age groups. A high %∆MCAv/%∆MAP response during the repeated stand‐to‐sit protocol was associated with low cerebrovascular reactivity to CO2 (r = −.39; p, Aging and age‐related cerebrovascular diseases are associated with impaired cerebrovascular function. The novel finding of this study is that older adults showed higher pressure–flow responses during repeated stand–sit transitions compared to younger adults, and that a high pressure–flow response was associated with low cerebrovascular reactivity to CO2. These results suggest that impaired vascular function and increased arterial stiffness may contribute to the pressure–flow responses observed in the older adults.

Introduction: Percutaneous closure of patent foramen ovale (PFO) in selected patients with cryptogenic cerebrovascular ischemic events (CEs) decreases the risk of recurrent stroke; however, optimal patient selection criteria are still under investigation. Candidates for PFO closure are usually selected from the pool of CE patients with a high risk of Paradoxical Embolism (RoPE) score. The RoPE score calculates the probability that PFO is causally related to stroke, based on PFO prevalence in patients with CE compared with that in healthy subjects. The latter has been set at 25% based on the average of autopsy and transesophageal echocardiography (TEE) studies.Methods: We conducted a comprehensive review of studies investigating PFO prevalence in general population and in patients with CE and non-CE using autopsy, TEE, transcranial Doppler (TCD) or transthoracic echocardiography (TTE). Studies were excluded if they (1) reported data from referred subjects with underlying cerebrovascular disease or (2) did not specify etiologically the events.Results: In healthy/control subjects, PFO prevalence was 24.2% (1,872/7,747) in autopsy studies, 23.7% (325/1,369) in TEE, 31.3% (111/355) in TCD, and 14.7% (186/1,267) in TTE studies. All diagnostic modalities included PFO prevalence was higher in CE compared with healthy/control population [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 2.5–3.8] and compared with non-CE (OR = 2.3, 95% CI = 2.0–2.6). In patients with CE, PFO prevalence in the young compared to the old was higher when the diagnostic modality was TEE (48.9 vs. 27.3%, p < 0.0001, OR = 2.6 with 95% CI = 2.0–3.3) or TCD (58.1 vs. 41%, OR = 1.9, 95% CI = 1.6–2.5), but not TTE (53.3 vs. 37.5%, p = 0.16). Regarding non-CE, PFO prevalence in the young compared to the old was higher when the diagnostic modality was TEE (20 vs. 12.9%, OR = 1.7, 95% CI = 1.0–2.8) but not TTE (10.4 vs. 7.8%, p = 0.75) or TCD (22.8 vs. 20.1%, p = 0.56).Conclusions: Given the limitations of autopsy and TEE studies, there is good reason not to take a fixed 25% PFO prevalence for granted. The estimation of degree of causality may be underestimated or overestimated in populations with PFO prevalence significantly lower or higher than the established. Given the high sensitivity, non-invasive nature, low cost, and repeatability of TCD, future large-scale TCD-based studies should investigate potential heterogeneity in PFO prevalence in different healthy racial/ethnic populations.

Traumatic brain injury is the leading cause of death in children. Children with severe TBI are in need of neurointensive care where the goal is to prevent secondary brain injury by avoiding secondary insults. Monitoring of cerebral blood flow (CBF) and autoregulation in the injured brain is crucial. However, there are limited studies performed in children to investigate this. Current studies report on age dependent increase in CBF with narrow age range. Low initial CBF following TBI has been correlated to poor outcome and may be more prevalent than hyperemia as previously suggested. Impaired cerebral pressure autoregulation is also detected and correlated with poor outcome but it remains to be elucidated if there is a causal relationship. Current studies are few and mainly based on small number of patients between the age of 0–18 years. Considering the changes of CBF and cerebral pressure autoregulation with increasing age, larger studies with more narrow age ranges and multimodality monitoring are required in order to generate data that can optimize the therapy and clinical management of children suffering TBI.

Individualized cerebral perfusion pressure (CPP) targets may be derived via assessing the minimum of the parabolic relationship between an index of cerebrovascular reactivity and CPP. This minimum is termed the optimal CPP (CPPopt), and literature suggests that the further away CPP is from CPPopt, the worse is clinical outcome in adult traumatic brain injury (TBI). Typically, CPPopt estimation is based on intracranial pressure (ICP)-derived cerebrovascular reactivity indices, given ICP is commonly measured and provides continuous long duration data streams. The goal of this study is to describe for the first time the application of robotic transcranial Doppler (TCD) and the feasibility of determining CPPopt based on TCD autoregulation indices. Electronic supplementary material The online version of this article (10.1007/s00701-018-3687-5) contains supplementary material, which is available to authorized users.

Background Neurovascular Coupling is the cerebral mechanism responsible for linking neuronal activity, cerebral metabolism and regional cerebral blood flow (CBF). The direct relation between functional brain activity during active, passive and motor imagery paradigms and changes in CBF has been widely investigated using different techniques. However, CBF changes have not been investigated beat by beat during robot assisted passive movement (PM) and motor imagery (MI) of lower limb, yet. Materials and methods We investigated beat-to-beat hemodynamic changes in 8 healthy subjects using TCD during MI and robot-assisted PM of lower limb. Results The results showed that MI and PM induce a significant CBFv increase and that PM and MI lead to similar hemodynamic changes in healthy subjects. Conclusions The findings may be useful to better understand the variation of CBFv in brain pathology and to develop more specific and efficient rehabilitation therapy protocols in neurological diseases, such as stroke.

The influence of cannabis use on the occurrence, clinical course and the treatment of the first psychotic episode (FEP) is well documented. However, the exact link is still not clearly established. The aim of this article is to review and report the noticed increase in the number of hospitalizations of young people with a clinical appearance of severe psychotic decompensation following cannabis consumption and to show the clinical challenges in treatment of the FEP. The case study describes the clinical course of a five selected patients with a diagnosis of the FEP and positive tetrahydrocannabinol (THC) urine test who were hospitalized in a similar pattern of events. They all have a history of cannabis consumption for at least 6 years in continuity and were presented with severe psychomotor agitation, disorganisation, confusion and aggression at admission. Although the chosen drug to treat all patients was atypical antipsychotic and benzodiazepines, the course of the disorder and the clinical response to therapy were noticeably different in each patient. The clinical presentation of FEP in cannabis users can be atypical and highly unpredictable from mild psychotic symptoms to severe substance intoxication delirium. In clinical practice clinicians treating new onset psychosis need to be watchful for cannabis and synthetic cannabinoids induced psychosis. Pharmacotherapeutic interventions include prompt and adequate use of the benzodiazepine, second-generation antipsychotic, and mood-stabilizers. Further research in the pharmacotherapy of cannabis-induced psychosis is required.

Long duration application of transcranial Doppler (TCD) for recording of middle cerebral artery (MCA) cerebral blood flow velocity (CBFV) has been fraught with difficulties.[1,2] Classically, TCD has been labor intensive, with limited ability to obtain uninterrupted recordings for extended periods. Furthermore, application of TCD within neurocritically ill for long durations has been limited given the complexity of care, regular bedside nursing care/patient manipulations, and presence of various other multi-modal monitoring devices. This is especially the case in traumatic brain injury (TBI) patients, with the adoption of extensive multi-modal monitoring. Within TBI, most TCD recordings, using standard widely available probes and holders, range from 30 minutes to 1-hour duration and are frequently interrupted due to shifting of the probe and signal loss.[3,4] Thus, we are typically left with a “snap-shot” recording with TCD examination, limiting our ability to extract valuable continuous variables, such as autoregulatory capacity.[3-5] Recent advances in robotics have led

The purpose of our study was to explore relationships between transcranial Doppler (TCD) indices of cerebrovascular reactivity and those derived from intracranial pressure (ICP). Goals included: A) confirming previously described co-variance patterns of TCD/ICP indices, and B) describing thresholds for systolic flow index (Sx; correlation between systolic flow velocity [FVs] and cerebral perfusion pressure [CPP]) associated with outcome. In a retrospective cohort of traumatic brain injury (TBI) patients: with TCD and ICP monitoring, we calculated various continuous indices of cerebrovascular reactivity: A) ICP (pressure reactivity index [PRx]: correlation between ICP and mean arterial pressure [MAP]; PAx: correlation between pulse amplitude of ICP [AMP] and MAP; RAC: correlation between AMP and CPP) and B) TCD (mean flow index [Mx]: correlation between mean flow velocity [FVm] and CPP; Mx_a: correlation between FVm and MAP; Sx: correlation between FVs and CPP; Sx_a: correlation between FVs and MAP; Dx: correlation between diastolic flow velocity [FVd] and CPP; Dx_a: correlation between FVd and MAP). We assessed the relationships via various statistical techniques, including: principal component analysis, agglomerative hierarchal clustering, and k-means cluster analysis (KMCA). We performed sequential χ2 testing to define thresholds associated with outcome for Sx/Sx_a. Outcome was assessed at 6 months via dichotomized Glasgow Outcome Score (GOS): A) Favorable (GOS 4 or 5) versus Unfavorable (GOS 3 or less), B) Alive versus Dead. We analyzed 410 recordings in 347 patients. All analyses confirmed our previously described co-variance of Sx/Sx_a with ICP-derived indices. Sx displayed thresholds of -0.15 for unfavorable outcome (p < 0.0001) and -0.20 for mortality (p < 0.0001). Sx_a displayed thresholds of +0.05 (p = 0.019) and -0.10 (p = 0.0001) for alive/dead and favorable/unfavorable outcomes. TCD systolic indices are most closely associated with ICP indices. Sx and Sx_a likely provide better approximation of ICP indices, compared with Mx/Mx_a/Dx/Dx_a. Sx provides superior outcome prediction, versus Mx, with defined thresholds.

Ti-6Al-4V has been extensively used in structural applications in various engineering fields, from naval to automotive and from aerospace to biomedical. Structural applications are characterized by geometrical discontinuities such as notches, which are widely known to harmfully affect their tensile strength. In recent years, many attempts have been done to define solid criteria with which to reliably predict the tensile strength of materials. Among these criteria, two local approaches are worth mentioning due to the accuracy of their predictions, i.e., the strain energy density (SED) approach and the theory of critical distance (TCD) method. In this manuscript, the robustness of these two methods in predicting the tensile behavior of notched Ti-6Al-4V specimens has been compared. To this aim, two very dissimilar notch geometries have been tested, i.e., semi-circular and blunt V-notch with a notch root radius equal to 1 mm, and the experimental results have been compared with those predicted by the two models. The experimental values have been estimated with low discrepancies by either the SED approach and the TCD method, but the former results in better predictions. The deviations for the SED are in fact lower than 1.3%, while the TCD provides predictions with errors almost up to 8.5%. Finally, the weaknesses and the strengths of the two models have been reported. © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

To investigate the effects of fluid resuscitation on cerebral hemodynamics in sepsis, the following set of transcranial Doppler (TCD) parameters was used: maximal change in flow velocity (FV) during stroke onset (acc), maximal FV during first (sys1) or second (sys2) phase of systole and mean diastolic FV (dias@560). We aim to evaluate changes in cerebral hemodynamics that result from (i) sepsis and (ii) adequate fluid resuscitation in critically ill septic patients. In the majority of 16 septic patients sys2 was initially absent but reappeared during the period of fluid resuscitation; whereas sys2 absence was never seen in healthy controls. Second, adequate fluid resuscitation resulted in a significant increase of the systolic FV components (acc, sys1, sys2 and systolic blood pressure); whereas the diastolic components (dias@560 and diastolic blood pressure) remained unchanged. Sys2 absence and reappearance in sepsis suggests that TCD could become a non-invasive alternative for hemodynamic monitoring.

BACKGROUND AND PURPOSE Sickle cell disease (SCD) is strongly linked to stroke across all haplotypes in the pediatric population. Transcranial Doppler (TCD) ultrasound is known to identify the highest risk group in African-Americans who need to receive and stay on blood transfusions, but it is unclear if the same flow velocity cut-offs can be applied to the Iranian population. We aimed to evaluate baseline TCD findings in Iranian children with SCD and no prior strokes. METHODS Children with genetically confirmed SCD (Arabian haplotype, homozygote) and without SCD (controls) were prospectively recruited from pediatric outpatient clinic over a period of 9 months. We performed TCD in both groups to determine flow velocities in the middle cerebral (MCA) and terminal internal carotid arteries (TICA). RESULTS Of 74 screened children, 60 met the inclusion/exclusion criteria (62% female; mean age 10±4 years). Baseline characteristics did not differ between the cases and controls, except hemoglobin (Hb) which was significantly lower in the SCD group (P

The aim of this study was to test feasibility of transcranial Doppler (TCD) and single photon emission computed tomography (SPECT) during compound neuroactivation task. The study was performed in 60 healthy right-handed volunteers. Cerebral blood flow velocity was measured by TCD in both middle cerebral arteries (MCA) at baseline and during computer game. The same stimulus and response pattern was used in 15 subjects that additionally underwent brain SPECT. Percentage differences between measurements were determined through quantitative result assessment. Both methods detected a statistically significant cerebral blood flow increase during neuroactivation. Correlation of TCD and SPECT showed statistically significant correlation only for the increase of cerebral blood flow velocity in the right MCA and for the right-sided cerebral blood flow increase, demonstrating that both methods partially measure similar cerebral blood flow changes that occur during neuroactivation. Comparison of TCD and SPECT showed TCD to be inadequately sensitive method for evaluation of cerebral blood flow during complex activation paradigm.

Summary Background The hypothesis that cerebral embolism plays no role in late septic encephalopathy and septic shock is based on indirect clinical evidence in the literature. The goal of this study was to prove the hypothesis that cerebral embolism plays no role in the pathophysiology of sepsis by direct evidence. Methods To examine this hypothesis, 20 patients with a late septic encephalopathy and septic shock were examined for direct evidence of ongoing cerebral embolism with transcranial Doppler for 30 min. Clinical data analysis included age, gender, cause of sepsis (gram-positive or -negative microorganisms), an index of severity of illness (the APACHE II score) and outcome (survivor/non survivor). Cerebral embolism was quantified by embolus detection software. Findings The study revealed no ongoing cerebral embolism during sepsis. Conclusion Cerebral micro-embolism plays no role in cerebral dysfunction during sepsis. This negative finding has an important clinical repercussion, because if transcranial Doppler exams should reveal ongoing cerebral embolism in septic shock, the embolism cannot be attributed to the septic shock itself rather it would indicate for a vigorous search for an embolic source.

We present the design, fabrication, and testing results of a single chip (2 cm×4 cm) micro gas separation column (μGC) with an embedded non-cascaded micro thermal conductivity detector (μTCD). Our unique design coupled with RIE-Lag enabled 3D etching technology offers several advantages over previously reported designs including simple 2-mask fabrication and operation (no flow restrictors needed), capability for different flow velocities for the column and detector, low dead volume, low pressure drop, low detector power consumption, and an injection-event indicator. Our particular design is distinctly different from others in the number of fluidic ports (only 2 ports), channel design (circular cross section), and column type (open tubular). This μGG- μTCD chip separated and detected a 200 nl sample mixture consisting of alkanes in less than 2 minutes with power dissipation less than 400 mW.

Objectives Transcranial Doppler (TCD) monitoring for micro embolic signals (MES), directly after carotid endarterectomy (CEA) may identify patients at risk of developing ischaemic complications. In this retrospective multicentre study, this hypothesis was investigated. Methods Centres that monitored for MES after CEA were identified by searching Medline. Individual patient data were obtained from centres willing to collaborate. The number of emboli in 1 h was computed. Uni- and multivariate logistic regression analyses were performed for the variables gender, age and number of MES. Discriminative ability of MES monitoring was investigated in a ROC curve. Results Nine hundred and ninety-one patients were monitored in the first 3 h after CEA. Two percent developed ischaemic cerebral complications. Univariate analysis revealed statistically significant associations between ischaemic cerebral complications and both gender and MES, but not age. In a multivariate analysis, ≥8 MES/h showed a statistically significant relationship with cerebral complications (OR 8.1, 95% CI 1.8–36), in contrast to gender (OR 2.2, 95% CI 0.9–5.5). The ROC curve yielded an AUC of 0.83 for monitoring of MES. Conclusions These results support the use of TCD monitoring for MES shortly after CEA in order to identify patients at risk of developing ischaemic cerebral complications.

Introduction Subarachnoid hemorrhage (SAH)represents hemorrhage in the space between arachnoidea and pia mater, due to aneurysm burst, spontaneously or as a consequence of trauma. It is condition that occurs more common in women than men, and its most common complications are rebleeding and vazospasm. As a result of vasospasm, develops ischemia in the portion of brain tissue that can cause additional neurological deficit. Transcranial Doppler Sonography (TCD) is a noninvasive ultrasound diagnostic method that allows monitoring of the state of intracerebral hemodynamics. Goal The goal is to follow the occurrence of vasospasm after SAH, by the TCD method. Material and methods We have analyzed 47 patients with SAH, by analyzing the presence of aneurysm, hypertension and smoking, and by the TCD method monitor the state of intracerebral hemodynamics during the first four days, then in the second and third week. Results SAH was more common in women (61.7%) than men (38.3%), and in the age range from 22 to 64 years. Aneurism was demonstrated in 61.7% of patients, more common in women, with hypertension 68.1% also more common in women and smoking in 87.2% of patients, also more common in women. By TCD method are recorded milder, elevated blood flow velocities at a quarter of patients in the first measurement, during the second measurement at all and it had significantly greater value, and the third measurement also more increased in about a quarter of patients, so that there is a statistically significant difference in the first and second, second and third measurement for each vessel separately, but not between the first and third measurement. Conclusion Predilection factors for SAH are aneurysms, hypertension and smoking. By using TCD method were recorded milder elevated blood flow velocity in the first days of SAH, with about a quarter of patients, significantly greater increase in blood flow velocity during the second week in all patients and also milder increase blood flow velocity in the third week of the start of SAH is a quarter of patients. TCD is the method of choice in the evaluation and management of vasospasm after SAH, which allows the prevention of delayed cerebral ischemia.

The objective of this paper is to give a new viewpoint in contact fatigue assessment in the spur gears. The presented research is based on up-to-date methods and multidisciplinary approach, and enables direct prediction of fatigue damage initiation in contact zones. The special attention is paid to the developing of model for precise simulation of spur gear teeth contact by finite element method (FEM). The contact stress calculation based on true contact involute geometry provides the stress gradients for theory of critical distances (TCD) application in damage initiation prediction. One particular spur gear pair is analysed for presenting the spur gear model developing.

The aim of this paper is to present an acquisition system and experimental measurements of a new micromachined Thermal Conductivity Detector (mu TCD), applied downstream of a gas-chromatography (GC) system. We describe a simple and innovative electronics for sensor control and data acquisition, outlining its resistance control, native imbalance compensation and automatic gain control (AGC) algorithm. Measurements and sensitivity tests have been carried out by connecting our TCD and acquisition system downstream of the microfluidic section and GC column of a commercial GC system. Comparing the results with those of a complete commercial GC system we observed a similar response and noise. Sensitivity measurements on toluene masses gave very good results, having observed a sensitivity of 15.2 +/- 0.6 mu Vs/ng. This high sensitivity will enable the use of the mu TCD in many portable applications like in-line quality control, industrial security and safety. We also show the good operation of the AGC algorithm.

OBJECTIVE Postoperative cognitive decline (POCD) is a frequent complication after cardiac surgery. Although intraoperative events are risk factors for POCD, the role played by preoperative hypoperfusion in cognitive decline has not yet been investigated. It is also unknown whether the impact of preoperative hypoperfusion in the left or right middle cerebral arteries (MCAs) can differentially account for POCD. The main aims of this study were to investigate whether preoperative cerebral hypoperfusion was associated with early POCD and whether lateralized hypoperfusion would differentially affect POCD in patients after cardiac surgery. METHODS Bilateral MCA continuous transcranial Doppler (TCD) sonography was preoperatively performed at rest in 31 right-handed patients who underwent cardiac surgery to detect cerebral blood flow (CBF) velocity. All patients completed a neuropsychological evaluation to assess attention, short-term memory, working memory, and psychomotor function before surgery and at discharge. POCD was defined using the standard deviation method. Logistic regression was used to investigate the association between hypoperfusion and POCD, controlling for common preoperative risk factors. RESULTS Fourteen patients (45%) exhibited POCD. Cerebral hypoperfusion in the left MCA selectively predicted the incidence of POCD (odds ratio = 0.90, p < .02), whereas CBF velocity in the right MCA was unrelated to POCD (odds ratio = 1.07, p = .39). CONCLUSIONS Patients who underwent cardiac surgery with reduced CBF velocity in the left MCA preoperatively are at greater risk for POCD. Left cerebral hypoperfusion may also represent an independent predictor of POCD in these patients. TCD evaluation may have substantial clinical benefits for the detection of patients at high risk of POCD after cardiac surgery.

Background and Purpose— Deep watershed infarcts are frequent in high-grade carotid disease and are thought to result from hemodynamic impairment, particularly when adopting a rosary-like pattern. However, a role for microembolism has also been suggested, though never directly tested. Here, we studied the relationships among microembolic signals (MES) on transcranial Doppler, rosary-like deep watershed infarcts on brain imaging, and cerebral hemodynamic compromise on positron emission tomography (PET), all in severe symptomatic carotid disease. We hypothesized that rosary-like infarcts would be significantly associated with worse hemodynamic status, independent of the presence of MES. Methods— Sixteen patients with ≥70% carotid disease ipsilateral to recent transient ischemic attack/minor stroke underwent magnetic resonance imaging including diffusion-weighted imaging, 15 O-PET, and transcranial Doppler. Mean transit time, a specific marker for hemodynamic impairment, was obtained in the symptomatic and unaffected hemispheres. Results— Eleven of 16 patients had rosary-like infarcts (Rosary+) and 8 patients had MES. Mean transit time was significantly higher ( P =0.008) in Rosary+ patients than in healthy controls ( n =10), and prevalence of MES was not different between Rosary+ and Rosary− patients. Contrary to our hypothesis, however, the presence of MES within the Rosary+ subset was associated ( P =0.03) with a better hemodynamic status than in their absence, with a significant ( P =0.02) negative correlation between mean transit time and rate of MES/h. Conclusions— Contrary to mainstream understanding, rosary-like infarcts were not independent of presence and rate of MES, suggesting that microembolism plays a role in their pathogenesis, probably in association with hemodynamic impairment. Pending confirmation in a larger sample, these findings have management implications for patients with carotid disease and rosary-like infarcts.

In this paper we present a micromachined Thermal Conductivity Detector (TCD), based on the Ultra Low Power (ULP) technology. The device has been electrically characterized with different Helium gas flows, via a microfluidic experimental setup. Extraction of global thermo-electric parameters, exploited for the development of an electro-thermal Spice model, has been performed directly from the experimental measurements and from 3-D electro-thermal FEM simulations of the device. The resulting Spice model agrees very well with the measurements, with a maximum error less than 0.22%.

Ghaydaa A Shehata1, Mohamed I Abdel-Kareem2, Abd ellah N Yassin4, Abdel Ahamid R El Adl31Department of Neurology, Faculty of Medicine, Assiut University, Assiut, Egypt; 2Department of Rheumatology, Physical Medicine and Rehabilitation Faculty of Medicine, 3Department of Internal Medicine, Faculty of Medicine, Al-Azhar University, Assiut, Egypt; 4Department of Diagnostic Radiology, Faculty of Medicine, Al-Azhar University, Cairo, Egypt Objective: To estimate the prevalence of neuropsychiatric disorders, cerebral atherosclerosis in patients with systemic lupus erythematosus (SLE) and explore the relation between transcranial duplex findings of different intracranial vessels with neuropsychiatric affect, and Systemic lupus erythematosus disease activity index (SLEDAI).Methods: Twenty-six consecutive SLE patients were evaluated for neurological and psychiatric disorders. Another 26 subjects matched with respect to age, sex, education, and socioeconomic status formed the control group. SLE disease activity was assessed by the SLEDAI. For each participant, a complete medical history was obtained and clinical, laboratory, and neurophysiological examinations, magnetic resonance imaging of the brain, transcranial duplex for intracranial vessels, and psychometric evaluations were performed. For the psychometric evaluation, we used the Modified Mini-mental State Examination and Cognitive Assessment Scale Inventory to assess cognitive function, and Hamilton Depression Rating Scale and Hamilton Anxiety Scale to assess symptoms of depression and anxiety.Results: Anxiety in 65.4% is the most prevalent manifestation followed by depression in 57.7%, headache in 38.5%, peripheral neuropathy in 26.9%, seizures in 23.1%, psychosis in 19.2%, radiculopathy and dementia in 15.4% for each, myositis in 11.5%, and stroke in 7.7%. There was a significant increased mean velocity and decreased pulsatility index of most studied intracranial vessels in both patient groups than in the control group. There was significant negative correlation between SLEDAI and transcranial Doppler findings in the pulsatility index of medial circumflex artery and procoagulant activity.Conclusion: Neurological disorders, cognitive impairment, depression, anxiety, psychosis and cerebrovascular changes detected by transcranial Doppler ultrasound are common in SLE.Keywords: SLE, SLEDAI, cognitive function, depression, anxiety, neurological disorders, TCD, cerebrovascular changes

A patient with a partially thrombosed fusiform giant basilar trunk aneurysm presented with devastating headache and symptoms of progressive brain stem compression. Having an aneurysm inaccessible for endovascular treatment, and after failing a vertebral artery balloon occlusion test, he was offered bypass surgery in order to exclude the aneurysm from the cerebral circulation and relieve his symptoms. A connection between the intracranial internal carotid artery and the superior cerebellar artery was created whereupon the basilar artery was ligated just distally to the aneurysm. The proximal anastomosis on the internal carotid artery was made using the excimer laser-assisted non-occlusive anastomosis (ELANA) technique, while a conventional end-to-side anastomosis was used for the distal anastomosis on the superior cerebellar artery. Intra-operative flowmetry showed a flow through the bypass of 40 ml/min after ligation of the basilar artery. An angiogram 24 hours later showed normal filling of the bypass and the vessels supplied by it, but also disclosed a subtotal occlusion of the proximal ipsilateral middle cerebral artery with delayed filling distally. The patient, who had a known thrombogenic coagulopathy, died the following day. Autopsy showed no signs of ischemia in the territories supplied by the bypass, but a thrombus in the proximal middle cerebral artery and massive acute hemorrhagic infarction with swelling in its territory and uncal herniation. Multiple fresh thrombi were found in the lungs. The ELANA anastomosis showed re-endothelialisation without thrombus formation on the inside.

Objectives: to identify the echodensity, stenosis of carotid plaques and cerebral collateral capacity that were associated with various ipsilateral presentations (retinal, cerebrovascular, asymptomatic). Design: cross-sectional study. Materials: forty-four patients, with 44 plaques associated with various presentations, were studied. Methods: the duplex images of the plaques were analysed echomorphologically in a computer by means of Grey Scale Median (GSM) [hypoechoic (low GSM), hyperechoic (high GSM)]. The percentage (%) reduction of the mean velocity in the middle cerebral artery (PRMCA) on transcranial Doppler, during clamping in carotid endarterectomy, was evaluated to distinguish the competent cerebral collateral supply (low PRMCA) from the non-competent one (high PRMCA). Results: the retinal symptoms were associated with plaques of low median GSM (0), severe median stenosis (90%) and low median PRMCA (0.31) as contrasted with the cerebrovascular symptoms (17, 84%, 0.47, respectively) and asymptomatic status (32, 83%, 0.4, respectively) [(p =0.038 (GSM), p=0.67 (stenosis), p=0.15 (PRMCA)]. The retinal and the cerebrovascular symptoms were distinct in terms of PRMCA (p=0.045). Conclusions: the retinal symptoms were produced by hypoechoic and possibly embologenic plaques, whereas the cerebrovascular ones possibly by the combination of carotid embolism and a non-competent cerebral collateral circulation. Asymptomatic status was associated with the absence of any relevant mechanism.

Background: six hours’ monitoring by transcranial Doppler (TCD) has been successful in directing Dextran therapy in patients at high risk of thrombotic stroke after carotid endarterectomy (CEA). Objectives: is 3 h of routine monitoring as effective as 6 h in the prevention of early postoperative thrombotic stroke? Design: prospective, consecutive study in all patients with an accessible cranial window. Methods: one hundred and sixty-six patients undergoing CEA underwent 3 h of postoperative monitoring by TCD. Any patient with >25 emboli detected in any 10 min period or those with emboli that distorted the arterial waveform were commenced on an incremental infusion of dextran 40. Results: the majority of patients destined to embolise will do so within the first 2 postoperative hours. Dextran therapy was instituted in nine patients (5%) and rapidly controlled this phase of embolisation although the dose had to be increased in three (33%). No patient suffered a postoperative carotid thrombosis but one suffered a minor stroke on day 5 and was found to have profuse embolisation on TCD; high dose dextran therapy was again instituted, the embolus count rate fell rapidly and he made a good recovery thereafter. Overall, the death and disabling stroke rate was 1.2% and the death/any stroke rate was 2.4%. Conclusion: three hours of postoperative TCD monitoring is as effective as 6 h in the prevention of postoperative carotid thrombosis.

Summary Background: Current protocols stress the importance of short-term diagnosis and treatment in recent TIA or minor stroke. The risk of a recurrent event can be predicted with embolus detection. Studies have shown that the presence of micro-emboli is associated with an increased risk of recurrent events. We explored in our patient population the effect of a zero-tolerance regime for cerebral embolism on outcome. Methods: Patients with a recent TIA or minor stroke were assigned to a study group or control group. Both groups were treated according to European Stroke guidelines, including prompt start of anti-thrombotic therapy, statins and short-term carotid arteries duplex scanning. The study group was subjected to TCD (Delica 9 series, Shenzen Delicate Electronics Co., LTD., China) embolus detection as soon as possible (EDS, SMT Medical, Wuerzburg, Germany). If emboli were detected, treatment was started immediately to stop cerebral embolization. This was achieved by either an altered drug regimen (clopidogrel) or angioplasty or carotid endarterectomy within one or two days. If carotid intervention was indicated in the control group, it was performed within two weeks, according to European guidelines. Results: 133 patients were enrolled in the study with three months follow-up. 61 patients were subjected to the control group, 72 patients were enrolled in the study group. Recurrent events occurred in 10.2% and 3.0%, respectively (p = 0.145). Conclusion: The current study shows a non-significant reduction in recurrent events in the study group. Probably sample size in this pilot study was insufficient to detect a significant decline. Nevertheless, the results show that embolus detection is feasible and the zero-tolerance regime may enhance the outcome of TIA and minor stroke patients. The findings support the start of a multicenter randomized trial to assess the clinical value of emboli detection in TIA and stroke care.