Middle Cerebral Artery Mean Flow Velocity Research Articles

Validation of the transcranial Doppler rescue criteria for mechanical thrombectomy.

Transcranial Doppler (TCD) identifies acute stroke patients with arterial occlusion where treatment may not effectively open the blocked vessel. This study aimed to examine the clinical utility and prognostic value of TCD flow findings in patients enrolled in a multicenter prospective study (CLOTBUST-PRO). Patients enrolled with intracranial occlusion on computed tomography angiography (CTA) who underwent urgent TCD evaluation before intravenous thrombolysis was included in this analysis. TCD findings were assessed using the mean flow velocity (MFV) ratio, comparing the reciprocal ratios of the middle cerebral artery (MCA) depths bilaterally (affected MCA-to-contralateral MCA MFV [aMCA/cMCA MFV ratio]). A total of 222 patients with intracranial occlusion on CTA were included in the study (mean age: 64±14years, 62% men). Eighty-eight patients had M1 MCA occlusions; baseline mean National Institutes of Health Stroke Scale (NIHSS) score was 16, and a 24-hour mean NIHSS score was 10 points. An aMCA/cMCA MFV ratio of <.6 had a sensitivity of 99%, specificity of 16%, positive predictive value (PV) of 60%, and negative PV of 94% for identifying large vessel occlusion (LVO) including M1 MCA, terminal internal carotid artery, or tandem ICA/MCA. Thrombolysis in Brain Ischemia scale, with (grade ≥1) compared to without flow (grade 0), showed a sensitivity of 17.1%, specificity of 86.9%, positive PV of 62%, and negative PV of 46% for identifying LVO. TCD is a valuable modality for evaluating arterial circulation in acute ischemic stroke patients, demonstrating significant potential as a screening tool for intravenous/intra-arterial lysis protocols.

Middle Cerebral Artery Blood Flow Velocity During Normal Pregnancy.

The present study aimed to evaluate resting middle cerebral artery (MCA) blood flow velocities using transcranial Doppler ultrasound (TCD) in healthy women at different stages of pregnancy, and to compare these velocities with those of normal controls. A total of 105 healthy normotensive pregnant women and 25 non-pregnant healthy controls were included in the study. We formed 3 groups according to gestational age: first trimester (7 to 13wk pregnant), second trimester (14 to 28wk pregnant), and third trimester (29 to 42wk pregnant). Age, body mass index, heart rate, arterial blood pressure, and hematological data were recorded and TCD was performed on the subjects. Regarding TCD, we evaluated the mean cerebral blood flow velocity, the peak systolic velocity, the end-diastolic flow velocity, S/D ratio, the pulsatility Index (PI) and the resistance Index (RI). The MCA mean blood flow velocities differed significantly among the groups (P<0.001) and were higher in the controls than those of the first trimester, second trimester, and third trimester groups (P<0.01, P<0.001, P<0.001 respectively). The MCA mean and peak blood flow velocities, and the PI and RI decreased significantly with advancing gestation. TCD is a noninvasive and non-toxic method of monitoring the adaptation of the maternal cerebral blood flow in pregnancy. The progressive decreases in the MCA mean and peak blood flow velocities, PI, and RI during gestation may be the result of chemical and neuronal factors. This study supports the need for additional studies using TCD to establish normative cerebral blood flow volumes throughout pregnancy.

Effects of traditional Chinese exercise on vascular function in patients with Alzheimer's disease: A protocol for systematic review and network meta-analysis of randomized controlled trials.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with an insidious onset, usually characterized by memory impairment, visual-spatial skill impairment, executive dysfunction and personality behavioral changes. Studies have confirmed that vascular dysfunction may precede AD pathological changes and can present as vascular malformations, atherosclerosis, and impaired self-regulation, and can affect oxidative stress and amyloidosis. Therefore, it is important to improve or prevent vascular dysfunction in AD patients. Regular exercise can effectively inhibit the production of reactive oxygen species during the occurrence of AD and can improve the reduction of cerebral blood flow due to AD. Previous studies have shown that exercise can achieve superior clinical results in improving vascular function in AD patients. Therefore, we hypothesize that traditional Chinese exercises (TCEs) may have a good clinical effect in improving vascular function in patients with AD. We will search "PubMed," "the Cochrane Library," "Embase," "Web of Science," "CINAHL," "ProQuest Dissertations and Theses," and "ProQuest-Health & Medical Collection," "CNKI," "SinoMed," "VIP," and "Wanfang Data" to find randomized controlled trials of the effects of TCEs on AD vascular function from the creation of the database to the present, including at least 1 indicator in carotid intima-media thickness (cIMT), middle cerebral artery mean flow velocity (MFV), blood indicators [Heme Oxidase-1 (HO-1), angiopoietin I (Ang I), vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor, matrix metalloproteinase-9 (MMP-9)], and arterial stiffness [(Ankle Brachial Index (ABI), pulse wave velocity (PWV)]. For the included literature, Excel 2019 will be used for data extraction and collection. For the indicators that can be netted for network meta-analysis, Surface Under the Cumulative Ranking for each exercise modality will be calculated with the help of Stata 16.0 and rank, where the higher the SUCRA score, the higher the ranking. For the indicators that cannot be netted, Review Manager 5.4 will be used for meta-analysis will be performed to evaluate the improvement effect of TCEs on AD patients. This meta-analysis will further determine the efficacy and safety of TCEs on vascular function in AD patients. In this study, randomized controlled trials of the effects of TCEs on vascular function in AD patients will be selected to provide evidence-based medical evidence for promoting the application of TCEs by observing the order of advantages and disadvantages of various exercise modalities through network meta-analysis.

Somatosensory evoked potentials and transcranial color Doppler monitoring in subarachnoid hemorrhage

The outcome of patients with subarachnoid hemorrhage (SAH) is broadly influenced by the complications that may result from the hemorrhage. We describe a series of subjects, in which neurophysiological monitoring executed by simultaneous recording of somatosensory evoked potentials (SEPs) and transcranial color Doppler (TCD) was performed to reveal possible, early complications following acute SAH. We described the absolute and interhemispheric values of SEPs from the upper limb and TCD examinations of the cerebral arteries in 13 subjects with acute SAH. In cases with middle cerebral artery (MCA) vasospasm, N20 SEP amplitude absolute values for the hemisphere involved in the vasospasm were much lower than the contralateral ones. The N20 amplitude ratio reduction correlated with reciprocal of MCA mean flow velocity values detected within each patient. In the subjects with early ischemic damage following SAH, the affected hemisphere showed N20 amplitude drop; in addition, the relationship between SEPs and TCD findings was missing. Our findings emphasize the utility of simultaneous evaluation of SEPs and TCD in SAH follow-up, since the two methods reflect different pathomechanisms of possible secondary brain damage in aneurysmal SAH.

Middle cerebral artery velocity is associated with the severity of MRI brain injury in neonates received therapeutic hypothermia

BackgroundNo previous study has investigated the relationship between middle cerebral artery (MCA) flow velocity and the severity of hypoxic ischemic encephalopathy (HIE) evaluated by magnetic resonance imaging (MRI). The aim of this study was to assess the correlation between cerebral blood flow as assessed by transcranial Doppler sonography and the severity of MRI brain injury in asphyxiated neonates with clinical HIE who received therapeutic hypothermia. MethodsThis retrospective cohort study was conducted in the neonatal intensive care unit at Chang Gung Memorial Hospital between April 2011 and May 2014. All neonates with HIE who received therapeutic hypothermia, transcranial Doppler examinations, and brain MRI were eligible. Brain MRI was performed at 11 days of age (interquartile range: 8.5–15 days) and the severity of MRI brain injuries was evaluated using the MR scoring system proposed by Barkovich et al. Serial transcranial Doppler examinations were performed in pre-hypothermia, hypothermia, and post-hypothermia phases. ResultsTwenty-six neonates met the eligibility criteria for this study. Neonates with an abnormal MCA mean flow velocity (MFV) during the hypothermia phase had a higher risk of brain MRI abnormalities (77.8% vs. 22.2%, p = 0.017) and neonates with abnormal high MFV of MCA had higher MR scores of basal ganglia (p = 0.022). However, there were no statistical differences between abnormal MFV of MCA and brain MRI abnormalities during pre- and post-hypothermia phases. ConclusionsDuring therapeutic hypothermia, mean cerebral blood flow velocity of the MCA was associated with the severity of MRI brain injury in the neonates with clinical HIE.

Transcranial Doppler could help to differentiate the types of dementia? A pilot study when CSF biomarkers are not available.

Our objective was to find a mean flow velocity (MFV) cut-off point to differentiate between normal and cognitive impaired patients using Clinical Dementia Rating (CDR) as a comparison method. To evaluate MFV (in cm/s) and pulsatility index (PI) from the left middle cerebral artery (MCA) and basilar artery using transcranial Doppler in a pilot study from an outpatient cognition unit and compare with cognitively normal older adults (at the age of sixty or older) from the Geriatric Ambulatory of Fluminense Federal University. We hypothesized that there is a MFV and PI cut-off point to potentially distinguish between normal and impaired cognition. Sixty-one patients with cognitive decline, including 18 with amnestic mild cognitive impairment (aMCI), 31 with probable Alzheimer disease (AD), 12 with vascular dementia (VD), and 10 cognitively normal older adults were included in the study. Patients with dementia (both AD and VD, p < 0.01) and aMCI (p < 0.05) had lower MFV than the control group in the MCA (32.2cm/s, 31.9cm/s, and 36.6cm/s, respectively) and dementia patients had higher PI compared to control (AD and VD, both p < 0.05). Basilar MFV showed to be no difference between the patients and the control group. A cut off value of 39.1cm/s was found in a ROC curve (area under de curve value 0.85, 95% CI 0.75-0.95) for mean MCA MFV to be predictive of cognitive impairment (CDR ≥ 0.5). In this study, the values of MCA MFV below 39.1cm/s were predictive of cognitive impairment according to CDR. TCD is an inexpensive method that could be used in a clinical scenario to help differentiate normal cognition from cognitive decline. Multicentric and longitudinal studies should be done to validate that.

Cerebral hemodynamics among non-diabetic hemodialysis patients

BackgroundCerebrovascular accidents and cognitive impairment is a frequent complication of end-stage renal disease (ESRD) on regular hemodialysis (HD).ObjectiveTo evaluate cerebral circulation hemodynamics in non-diabetic prevalent hemodialysis patients by transcranial Doppler (TCD).Patients and methodsThe cross-sectional study included 50 ESRD patients on regular hemodialysis > 6 months in Ain Shams University Hospitals, Cairo, Egypt. Diabetic patients; chronic liver disease patients Child-Pugh class B or C; smokers; history of evident of cardiac, peripheral, or cerebrovascular insult; uncontrolled hypertension; anemia; collagen disease; and active infection were excluded from the study. An assessment of cerebral circulation hemodynamics by TCD in non-dialysis day to examine mean flow velocity (MFV) in the middle cerebral artery (MCA) and posterior cerebral artery (PCA).ResultsAn assessment of cerebral circulation hemodynamics revealed that 16 (32%) of the patients showed decrease MFV in MCA and 30 (60%) were normal. Regarding MFVs in PCA, 13 (26%) of the patients showed decrease MFVs, 33 (66%) were normal, and 4 (8%) of the patients failed due to poor bone window, significant reduction of MCV and PCA velocities in HD with urea reduction ratio < 65%, and a significantly negative correlation of MFV, PCA, and hemoglobin level (P < 0.05).ConclusionThere is a high frequency rate of decreased MCA and PCA MFV (32%, 28%), respectively, among non-diabetic prevalent hemodialysis patients with significant correlation to hemodialysis adequacy.

Correlation between Framingham risk score and degree of asymptomatic intracranial artery stenosis on stroke prone person

Intracranial artery stenosis is the most frequent cause of ischemic stroke. Yet there is no recommendation for population-based screening with the goal of primary stroke prevention strategies. Framingham risk score D’Agostino’s modification has been shown as highly accurate screening to assess the risk of intracranial artery stenosis that lead to stroke. The aims of study to determine the correlation between Framingham risk score and degree of asymptomatic intracranial artery stenosis among stroke prone person. In the study, 32 patients were included. Intracranial stenosis was assessed by transcranial Doppler (TCD). Stenosis defined if the mean flow velocity (MFV) value was abnormal. Artery stenosis was most common in the left middle cerebral artery (MCA) (34.4%). After multiple linear regression analysis was done, only MFV of right carotid siphon artery (CSA) (p = 0.060; r = - 0.493), MFV of left anterior cerebral artery (ACA) (p = 0.073; r = 0.332), MFV of left MCA (p = 0.065; r = 0.341), had significant correlation. The conclusion appears that the stroke risk score has moderate correlation with the degree of asymptomatic intracranial artery stenosis, especially with MFV of right CSA, left ACA and left MCA.

Predictive value of transcranial doppler ultrasound for cerebral small vessel disease in elderly patients.

To investigate the predictive value of transcranial Doppler (TCD) ultrasound for cerebral small vessel disease in elderly patients. Transcranial Doppler ultrasound and magnetic resonance imaging (MRI) were performed on 184 elderly patients with cerebral small vessel disease. The relationship of clinical characteristics and TCD ultrasound parameters with severe white matter lesions (WMLs) in MRI were investigated by univariate analysis and multivariate analysis. The univariate analysis showed that age, left middle cerebral artery (MCA) mean flow velocity, right MCA mean flow velocity and mean MCA pulsatility index were significantly correlated with severe WMLs (p < 0.05). The multivariate logistic regression analysis showed that only age (odds ratio: 1.21; 95%CI: 1.10-1.36; p < 0.01) and MCA pulsatility index (dominance ratio: 1.13; 95%CI: 1.06-1.80; p = 0.02) were significantly correlated with severe WMLs. The analysis of TCD ultrasound parameters showed that when the cut-off for MCA pulsatility index was 1.04, it could identify severe WMLs. The area under the curve was 0.70 (95%CI: 0.60-0.80). The sensitivity and specificity were 63.0% and 72.0%, respectively. The positive and negative predictive values were 35.4% and 86.6%, respectively. The MCA pulsatility index in TCD ultrasound is significantly correlated with severe WMLs; and TCD ultrasound can guide selective MRI for the detection of WMLs.

Prediction of functional outcome using the novel asymmetric middle cerebral artery index in cryptogenic stroke patients.

BackgroundEtiology is unknown in approximately one-quarter of stroke patients after evaluation, which is termed cryptogenic stroke (CS). The prognosis of CS patients is largely undetermined. We created a novel index from transcranial Doppler parameters including mean flow velocity (MV) and pulsatility index (PI) and investigated whether the calculation of asymmetry in the novel parameter can predict functional outcomes in CS patients.MethodsWe made the middle cerebral artery (MCA) index (%) as a novel parameter, which was calculated as 100 X (MCA MV + MCA PI X 10) / (MCA MV–MCA PI X 10). The MCA asymmetry index (%) was also calculated as 100 X (|Rt MCA index–Lt MCA index|) / (Rt MCA index + Lt MCA index) / 2. Poor functional outcomes were defined as modified Rankin Scale score (mRS) ≥3 at 3 months after stroke onset.ResultsA total of 377 CS patients were included. Among them, 52 (13.8%) patients had a poor outcome. The overall MCA asymmetry index was two-fold higher in CS patients with a poor outcome (10.26%) compared to those with a good outcome (5.41%, p = 0.002). In multivariable analysis, the overall MCA asymmetry index (OR, 1.054, 95% CI, 1.013–1.096, p = 0.009) and the cutoff value of the overall MCA asymmetry index >9 were associated with poor outcomes at 3 months (OR, 3.737, 95% CI, 1.530–9.128, p = 0.004).ConclusionWe demonstrated that the novel asymmetric MCA index can predict short-term functional outcomes in CS patients.

Electroacupuncture Improves Cerebral Vasospasm and Functional Outcome of Patients With Aneurysmal Subarachnoid Hemorrhage.

Cerebral vasospasm is the major cause of a poor outcome after aneurysmal subarachnoid hemorrhage (aSAH), and effective treatments for vasospasm are limited. The purpose of this study was to research the impact of electroacupuncture (EA) on cerebral vasospasm and the outcomes of patients with aSAH. A total of 60 age- and sex-matched aSAH patients were collected from Ningbo First Hospital between December 2015 and June 2017. All patients were given a basic treatment of nimodipine and randomized into two groups. The study group was treated with EA therapy on the Baihui (GV20) acupoint, and the control group was given mock transcutaneous electrical nerve stimulation. Cerebral vasospasm was measured by computed tomographic perfusion (CTP) and transcranial doppler (TCD). The mean flow velocity (MFV) in the middle cerebral artery (MCA), cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) of the patients were analyzed. The CBV and MTT exhibited significant differences between the study and control groups on the 1st (p = 0.026 and p = 0.001), 7th (p = 0.020 and p < 0.001), and 14th (p = 0.001 and p < 0.001) day after surgery, whereas CBF exhibited statistical significance only on the 14th day after surgery (p = 0.002). The MFV in MCA were significantly reduced after EA treatment in all patients (all p < 0.001). Additionally, the MFV in the MCA in patients treated with EA were considerably reduced compared with those of the control group (3rd day p = 0.046; 5th day, p = 0.010; 7th day, p < 0.001). Moreover, better outcomes were noted in the EA-treated group for the 1st month (p < 0.001) and 3rd month (p = 0.001) after surgery than in the control group. In conclusion, EA represents a potential method to treat cerebral vasospasm after aSAH and can improve the outcomes of patients with aSAH.

Investigation of ischemic and demyelinating lesions by cerebral vasoreactivity based on transcranial Doppler sonography: a comparative study.

PurposeVariations of cerebral blood flow in response to hypoxia and hyperoxia in different disease conditions can provide new insights into disease etiopathogenesis. This study aimed to determine the characteristics of cerebral vasoreactivity for ischemia and demyelination.Materials and methodsThis case–control study included: 28 patients with lacunar infarctions verified by history, physical examination, and MRI; 28 age- and sex-matched healthy controls; 28 patients with relapsing–remitting multiple sclerosis (MS), based on McDonald criteria; and 28 age- and sex-matched healthy controls for the MS group. Transcranial Doppler sonography was undertaken in all subjects to calculate the mean flow velocity (MFV) of the right middle cerebral artery (MCA) and, after a breath-holding (BH) maneuver, the breath-holding index (BHI) was determined.ResultsThere was no significant difference of BHI and changes of MFV of the MCA in MS patients compared to controls (1.02 ± 0.4 vs 1.02 ± 0.3, p = 0.993; and 16.8 ± 8.1 vs 11.3 ± 10.8, p = 0.057). BHI in patients with lacunar infarctions was significantly lower (0.8 ± 0.4 vs 1.2 ± 0.3, p < 0.001) compared to controls. The BHI (p = 0.040) and variations of MFV of MCA (p = 0.007) in MS patients were significantly higher than in patients with lacunar infarctions. The vasoreactivity of demyelinating lesions was higher than that of ischemic ones.ConclusionTherefore, cerebral vasoreactivity determined by transcranial Doppler could be utilized for differentiating demyelinating from ischemic lesions.

FV 3 Functional transcranial Doppler (fTCD) during cold-induced pain in the oral cavity and ice cream headache

Background An increase of mean flow velocity (MFV) in cerebral arteries can be monitored during processing of visual information ( [Aaslid, 1987] , [Rihs et al., 1999] ), while speaking ( Cupini et al., 1996 ), memory tasks ( Vollmer-Haase et al., 1998 ) and movements of one hand ( Orlandi and Murri, 1996 ) by functional transcranial Doppler (fTCD). The processing of sensitive information ( Duschek et al., 2012 ) or pain ( Mages et al., 2016 ) also leads to an increase in blood flow. Drinking ice-cold water can cause pain in the oral cavity and an ice cream headache ( Mages et al., 2016 ). In this study, it should be investigated whether the oral pain or the headache cause measurable changes of the MFV in the middle cerebral artery (MCA). Methods The MFV in both MCA were measured simultaneously during the drinking of 200 ml of lukewarm (22 °C) and 200 ml of ice-cold (0 °C) water in 77 young, healthy volunteers (see Fig. 1 ). After the experiments the occurrence of cold-induced pain in the oral cavity and ice cream headache was documented. Results See Table 1 . Discussion Drinking of liquid leads to a slight increase in the MFV in the ACM (lukewarm water: 2.8%, ice cold water 3.3%). The occurrence of ice cream headache is associated with a MFV increase of about 5% (difference group III with I). The MFV changes during cold-induced pain in the oral cavity are not significant and small (difference group IV and III 1.3%, group II and I 1.5%). Significant increases of MFV in subjects with cold-induced pain in the oral cavity and concomitant ice cream headache were observed. If the diameter of the MCA was constant, it can be concluded that the increase in MFV upon cold ingestion corresponds to an increase in cerebral blood flow.

Middle cerebral artery flow velocity increases more in patients with delayed intraparenchymal hemorrhage after Pipeline

ObjectivePipeline Embolization Devices (PED) are commonly used for endovascular treatment of cerebral aneurysms but can be associated with delayed ipsilateral intraparenchymal hemorrhage (DIPH). The role that altered intracranial hemodynamics may...

Integrative Physiology of Brain Perfusion During Extreme Chemoreflex Manoeuvers

Both cerebral perfusion pressure (CPP) and vascular conductance (CVC) contribute to blood flow. Yet, rarely are these factors considered in cerebrovascular reactivity studies, in favour of the change in mean flow velocity (MFV) for a given dilatory stimulus such as carbon dioxide, an approach that can ignore the potential contributions of CPP. We tested the hypothesis that both CVC and CPP facilitate the increase cerebral perfusion during progressive chemoreflex stress. In healthy free divers (n=7; 1 female; age range = 22 to 34 years) middle cerebral artery MFV (transcranial Doppler ultrasound; Multigon), mean arterial pressure (MAP; Finometer), central venous pressure (CVP; dependent antecubital vein), end tidal CO2 (ETCO2; ADInstruments), and hemoglobin saturation (HbSat, pulse oximetry) were measured while CPP (MAP‐CVP) and CVC (MFV/CPP) were calculated. These indices were obtained at baseline, during a 2‐min preparatory phase of rebreathing to establish early effects on CVC and CPP, and then during i) extended rebreathe (RB), ii) apnea at total lung capacity (TLC), or iii) apnea at functional residual capacity (FRC); each stress assigned randomly and continued to volitional tolerance. ETCO2 increased 12–18 mmHg in all conditions (Effect of Time, P&lt;0.001; no Condition effect). The 59% HbSat level attained during RB was lower than FRC (78%) or TLC (80%) (Condition x Time interaction P&lt;0.001). MFV was similar at baseline (TLC, 52±11; FRC, 49±8; RB, 51±11 cm/s) and increased similarly (Time effect, P&lt;0.001) in TLC (111±17 cm/s), FRC (106±18 cm/s) and RB (108±11 cm/s; No Condition effect). CVC increased similarly in each condition (TLC, 49±11; FRC, 57±31; RB, 61±23%; Effect of Time P&lt;0.001; No Condition effect). Also, CPP increased similarly in each condition (TLC, 46±16%; FRC, 42±14%; RB, 36±16%; Time effect P&lt;0.001). The CVC response typically plateaued following the preparatory 2‐min rebreathe phase of each protocol whereas the majority of the CPP response occurred during the Apnea and extended rebreathe phases. Therefore, the determinants of the linear increase in MFV across the preparatory rebreathe phase, and the subsequent RB, TLC, or FRC condition phases, switched from a largely CVC mechanism at lower levels of stress, to increased CPP during the extended Apnea or RB manoeuvres, regardless of differences in HbSat.Support or Funding InformationNSERC discovery grant # 217916‐2013 awarded to J.K.S.

Abstract TP407: Effects of Remote Ischemic Conditioning on Cerebral Small Vessel Disease Outcomes

Objective: To evaluate the preliminary efficacy of remote ischemic conditioning (RIC) on patients with cerebral small vessel disease (SVD). Methods: Thirty patients diagnosed with symptomatic SVD within 30 days of onset were enrolled in this prospectively randomized controlled study for 1 year. All patients received routine medical treatment including treating vascular risk factors according to the guideline. Patients in the experimental group (n=14) were administered 5 cycles consisting of ischemia followed by reperfusion for 5 minutes on bilateral upper limbs twice daily for 1 year. Those in the control group (n=16) underwent sham ischemia-reperfusion cycles. Primary outcome was the change of cognitive function measured by mini-mental state examination (MMSE) and montreal cognitive assessment scale (MoCA), and secondary outcomes were changes of plasma biomarkers, cerebral hemodynamic parameters measured by vascular ultrasound and brain lesions measured by MRI FLAIR both at baseline and at the end of 1 year visit. Results: Compared with patients in the control group, patients in the RIC group had higher flow velocity (FV), and lower pulsatility index (PI), but without statistical difference. Patients in the RIC group had improvement in visuospatial and executive abilities (3.86±1.03 vs. 4.43±0.85, p=0.026), reduced plasma triglyceride (1.60±0.74 vs. 1.25±0.38, p=0.019), low density lipoprotein (2.89±0.81 vs. 2.26±0.67, p=0.003) and homocysteine (15.66±10.11 vs. 13.66±9.80 p=0.017). Similarly in the RIC group, the diastolic flow velocity (DFV) of middle cerebral artery (MCA) (right: 33.93±7.67 vs. 36.93±6.12, p=0.032; left: 33.93±7.67 vs. 36.93± 6.12, p=0.032) and the mean flow velocity (MFV) of left MCA (35.00±5.04 vs. 39.50±5.59, p=0.003) increased, and the PI of MCA (right: 1.11±0.19 vs. 1.02±0.14 p=0.030; left: 1.10±0.22 vs. 0.99±0.14, p=0.037) decreased. Conclusion: RIC appears to be potentially effective for improving cognition, enhancing cerebral perfusion, and modifying vascular risk factors in SVD patients. Further studies focusing on long-term neurological outcomes and potential mechanisms underlying RIC on SVD patients are needed.

The Interventional Effect of Remote Ischemic Preconditioning on Cerebral Small Vessel Disease: A Pilot Randomized Clinical Trial

Background: Remote ischemic preconditioning (RIPC) of the limb has been shown to induce ischemic tolerance in basic and clinical studies that focused on sustained large artery occlusion rather than small vessel disease (SVD). This study aimed to evaluate the protective effects of brief repetitive limb RIPC on patients with cerebral SVD. Methods: Seventeen patients with cerebral SVD were enrolled. Patients underwent 5 ischemia-reperfusion cycles of preconditioning/sham preconditioning on both upper limbs twice a day for 1 year. Cerebral hemodynamic indexes, brain lesions, cognitive functions and assessment outcomes of dizziness handicap inventory (DHI) were analyzed. Results: In the RIPC group, the mean flow velocity (MFV) of the left middle cerebral artery (MCA) was accelerated (57.33 (52.33-61.34) vs. 51.33 (48.83-58.33), respectively; p = 0.038), and the post-treatment DHI score was reduced (18 (13-19) vs. 34 (21-45), respectively; p = 0.043). The post-treatment volume of the white matter lesions (WMLs) was also reduced (4.19 (2.96-7.25) vs. 6.06 (4.67-10.95), respectively; p = 0.050). There was no remarkable difference between the 2 groups either before or after treatment. Conclusion: The present study indicates that RIPC has potential beneficial effects on cerebral SVD by increasing the MFV of MCA, decreasing the DHI score as well as the volume of WMLs in patients with SVD.

Effects of High-Frequency Repetitive Transcranial Magnetic Stimulation on Cerebral Hemodynamics in Patients with Disorders of Consciousness: A Sham-Controlled Study

Objective: This study aimed to determine the effects of high-frequency repetitive transcranial magnetic stimulation (rTMS) on cerebral hemodynamics in patients with disorders of consciousness (DOC). Methods: In this sham-controlled study, 20-Hz and sham rTMS were applied over the left primary motor cortex (M1) of 5 patients in a vegetative state (VS) and 5 patients in a minimally conscious state (MCS). The clinical behavior and cerebral blood flow (CBF) velocity in the bilateral middle cerebral artery (MCA) of the patients were evaluated before and after rTMS. Results: Compared with the VS group, the MCS group exhibited significant increases in peak systolic velocity (PSV; p = 0.024) and mean flow velocity (MFV) of the left MCA that were temporally related to the rTMS (p = 0.042). There were no significant effects on CBF velocity in the sham-stimulation group or the right MCA. Conclusions: High-frequency rTMS exerts different effects on CBF depending on the level of consciousness in patients with DOC such that it increased PSV and MFV in patients in a MCS. These effects may be related to the varying degrees of disrupted neurovascular coupling and the autonomic control of the cerebral hemodynamics in patients in a VS or MCS.

Low flow velocity in the middle cerebral artery predicting infarction after bypass surgery in adult moyamoya disease.

OBJECTIVE Direct and indirect bypass surgeries are recognized as the most effective treatments for preventing further stroke in adults with moyamoya disease (MMD). However, the risk factors for postoperative infarction after bypass surgery for MMD are not well established. Therefore, the objective of this study was to investigate the risk factors for postoperative infarction. In particular, the authors sought to determine whether transcranial Doppler (TCD) ultrasonography measurements of mean flow velocity (MFV) in the middle cerebral artery (MCA) could predict postrevascularization infarction. METHODS The medical records of patients with MMD who underwent direct bypass surgery at the authors' institution between July 2012 and April 2015 were reviewed. The MFV in the MCA was measured with TCD ultrasonography and categorized as high (> 80 cm/sec), medium (40-80 cm/sec), and low (< 40 cm/sec). Postoperative MRI, including diffusion-weighted imaging, was performed for all patients within a week of their surgery. Angiographic findings were classified according to the Suzuki scale. Postrevascularization infarction was defined as any diffusion restriction on postoperative MRI scans. Postoperative neurological status was assessed through a clinical chart review, and the modified Rankin Scale was used to evaluate clinical outcomes. RESULTS Of 43 hemispheres in which bypass surgery for MMD was performed, 11 showed postrevascularization infarction. Ten of these hemispheres had low MFV and 1 had medium MFV in the ipsilateral MCA. In both univariate and multivariate analyses, a low MFV was associated with postrevascularization infarction (adjusted OR 109.2, 95% CI 1.9-6245.3). A low MFV was also statistically significantly associated with more advanced MMD stage (p = 0.02). CONCLUSIONS A low MFV in the ipsilateral MCA may predict postrevascularization infarction. Bypass surgery for MMD appears to be safe in early-stage MMD. Results of TCD ultrasonography provide clinical data on the hemodynamics in MMD patients before and after revascularization.

Abstract WP350: Pumping Against Gravity - Cardiac Function Affects Fluctuations in Cerebral Blood Flow Caused by Head Position Change in Acute Ischemic Stroke

Introduction: Acute ischemic stroke (AIS) patients often have the head-of-bed (HOB) elevated to 30 0 while in the Emergency Department (ED). Flat HOB positioning has been shown to impact cerebral flow. Whether this holds true in undifferentiated, ED stroke patients is unknown. Hypothesis: We tested the hypothesis that 0 0 HOB positioning improves middle cerebral artery (MCA) mean flow velocity (MFV) in AIS compared to 30 0 . We secondarily tested the hypothesis that lower cardiac output (CO) is associated with greater fluctuation of MFV. Methods: This was a quasi-experimental study with repeat measurements of MCA MFV at 30 0 and 0 0 HOB position. Patients &gt; 18 years presenting to the ED within 12 hours of symptom onset and a NIHSS ≥ 4 were eligible. After applying non-invasive monitoring of mean arterial pressure (MAP) and CO, an investigator used transcranial Doppler to obtain bilateral MCA MFV at 30 0 and 0 0 HOB position. If a signal was unobtainable on the ischemic side, the contralateral MFV was used for analysis. The primary analysis comprised all subjects with confirmed stroke on subsequent imaging and included student t-test for continuous measures. Secondary analysis used multiple linear regression to test if baseline NIHSS, age, MAP and CO were associated with changes in MFV. Results: There were 38 subjects enrolled, of whom 32 had confirmed AIS and were included in analysis. The mean age was 66 (±15) years and NIHSS 7 (±6). Stroke location was mixed (50% lacunar, 25% posterior and 25% anterior circulation). Averaged across all subjects, the MFV did not significantly increase when changing the HOB position from a 30 0 to 0 0 (+0.7 cm/s, 95% CI -1.6 to 3.1). Nevertheless, 16% (95% CI 5-33%) of subjects had a ≥ 20% increase and 47% (95% CI 29-65%) had any increase in MFV at 0 0 compared to 30 0 HOB. Adjusting for age, NIHSS and MAP, lower CO was associated with greater change in MFV (+2 cm/s [95% CI 0.2-3.7 cm/s] for every 1 L/min lower cardiac output, p=0.03). Conclusions: In conclusion, in a mixed sample of ED AIS patients, lower HOB position does not significantly impact cerebral flow on average, yet a considerable proportion of individuals may benefit from lower HOB position. Low cardiac output may identify those that benefit most.