Middle Cerebral Artery Flow Velocity Research Articles

Aggressive and Autoaggressive Behaviors in Patients with Autism Spectrum Disorder in Correlation with Middle Cerebral Artery Flow Velocity.

Background/Objectives The purpose of this study was to see whether there is a correlation between the behavior of autism spectrum disorder patients and brain abnormalities based on the velocity of blood flow in the MCA (middle cerebral artery). Methods: The use of HAP (High Altitude Protection) suits, which are used in aviation, to treat patients with ASD (autism spectrum disorder) causes significant changes in their functioning and physiological processes. These changes are not only noted in psychological tests but are observed in cerebral blood flow using transcranial Doppler ultrasound of the MCA. Results The results of this study made it possible to distinguish two groups with different flow velocities, which can be characterized as flows of less than 80 cm/s and flows of more than 80 cm/s. In addition, it was shown that in patients with elevated blood flow velocity, aggressive behaviors account for 86.96%, while self-aggressive behaviors account for 65.2%. On the other hand, in the case of patients with reduced flow velocity, i.e., less than 80 cm/s, the rate of aggressive behavior is 20% and that of self-aggressive behavior is 50%. The experiment showed that after therapy, there is a normalization of blood flow, which increased in the case of patients with a reduced flow rate below 80 cm/s and, in the case of elevated blood velocity after therapy, decreased towards normal levels. Conclusions The observed rate of normalization of flow velocities in the MCA translated into significant changes in the behavior and functioning of patients in the neurotypical direction, which was noticeable in the psychological tests conducted.

Effects of Intermittent Hypoxia Protocols on Cognitive Performance and Brain Health in Older Adults Across Cognitive States: A Systematic Literature Review.

The rise in the aging population highlights the need to address cognitive decline and neurodegenerative diseases. Intermittent hypoxia (IH) protocols show promise in enhancing cognitive abilities and brain health. This review evaluates IH protocols' benefits on cognition and brain health in older adults, regardless of cognitive status. A systematic search following PRISMA guidelines was conducted across four databases (PubMed, Scopus, Web of Science, and Cochrane Library) and two registers, covering records from inception to May 2024 (PROSPERO: CRD42023462177). Inclusion criteria were: 1) original research with quantitative details; 2) studies involving older adults, with or without cognitive impairment; 3) studies including IH protocols; 4) articles analyzing cognition and brain health in older adults. Seven studies and five registered trials met the criteria. Findings indicate that Intermittent Hypoxia Training (IHT) and Intermittent Hypoxia-Hyperoxia Training (IHHT) improved cognitive functions and brain health. Intermittent Hypoxic Exposure (IHE) improved cerebral tissue oxygen saturation, middle cerebral arterial flow velocity, and cerebral vascular conductance, particularly in cognitively impaired populations. IHT and IHHT had no significant effect on BDNF levels. There is a lack of studies on IHHE in older adults with and without cognitive impairment. IH protocols may benefit cognition regardless of cognitive status. IHT and IHE positively affect cerebral outcomes, with all protocols having limited effects on BDNF levels. Future research should standardize IH protocols, investigate long-term cognitive effects, and explore neuroprotective biomarkers. Combining these protocols with physical exercise across diverse populations could refine interventions and guide targeted therapeutic strategies.

A Randomised Controlled Trial of SFX-01 After Subarachnoid Haemorrhage - The SAS Study.

SFX-01 is a novel drug for clinical delivery of sulforaphane (SFN). SFN is a potent nuclear factor erythroid 2-related factor 2 activator that reduces inflammation and oxidation, improving outcomes after subarachnoid haemorrhage (SAH) in animal models. This was a multi-centre, double-blind, placebo-controlled, parallel-group randomised clinical trial to evaluate the safety, pharmacokinetics and efficacy of 28days of SFX-01 300mg BD in patients aged 18-80 with spontaneous SAH and high blood load on CT. Primary outcomes were (1) safety, (2) plasma and CSF SFN and metabolite levels and (3) vasospasm on transcranial doppler ultrasound. Secondary outcomes included CSF haptoglobin and malondialdehyde and clinical outcome on the modified Rankin Scale (mRS) and SAH outcome tool (SAHOT). A total of 105 patients were randomised (54 SFX-01, 51 placebo). There were no differences in adverse events other than nausea (9 SFX-01 (16.7%), 1 placebo (2.0%)). SFN, SFN-glutathione and SFN-N-acetyl-cysteine AUClast were 16.2, 277 and 415h × ng/ml. Plasma SFN was higher in GSTT1 null individuals (t = 2.40, p = 0.023). CSF levels were low with many samples below the lower limit of quantification and predicted by the CSF/serum albumin ratio (R2 = 0.182, p = 0.039). There was no difference in CSF haptoglobin (1.981 95%CI 0.992-3.786, p = 0.052) or malondialdehyde (1.12 95%CI 0.7477-1.687, p = 0.572) or middle cerebral artery flow velocity (1.04 95%CI 0.903-1.211, p = 0.545) or functional outcome (mRS 1.647 95%CI 0.721-3.821, p = 0.237, SAHOT 1.082 95%CI 0.464-2.525, p = 0.855). SFX-01 is safe and effective for the delivery of SFN in acutely unwell patients. SFN penetrated CSF less than expected and did not reduce large vessel vasospasm or improve outcome. Trial registration: NCT02614742 clinicaltrials.gov.

Dynamic changes in glymphatic function in reversible cerebral vasoconstriction syndrome.

The pathophysiology of the reversible cerebral vasoconstriction syndrome (RCVS) remains enigmatic and the role of glymphatics in RCVS pathophysiology has not been evaluated. We aimed to investigate RCVS glymphatic dynamics and its clinical correlates. We prospectively evaluated the glymphatic function in RCVS patients, with RCVS subjects and healthy controls (HCs) recruited between August 2020 and November 2023, by calculating diffusion-tensor imaging along the perivascular space (DTI-ALPS) index under a 3-T MRI. Clinical and vascular (transcranial color-coded duplex sonography) investigations were conducted in RCVS subjects. RCVS participants were separated into acute (≤ 30days) and remission (≥ 90days) groups by disease onset to MRI interval. The time-trend, acute stage and longitudinal analyses of the DTI-ALPS index were conducted. Correlations between DTI-ALPS index and vascular and clinical parameters were performed. Bonferroni correction was applied to vascular investigations (q = 0.05/11). A total of 138 RCVS patients (mean age, 46.8years ± 11.8; 128 women) and 42 HCs (mean age, 46.0years ± 4.5; 35 women) were evaluated. Acute RCVS demonstrated lower DTI-ALPS index than HCs (p < 0.001) and remission RCVS (p < 0.001). A continuously increasing DTI-ALPS trend after disease onset was demonstrated. The DTI-ALPS was lower when the internal carotid arteries resistance index and six-item Headache Impact test scores were higher. In contrast, during 50-100days after disease onset, the DTI-ALPS index was higher when the middle cerebral artery flow velocity was higher. Glymphatic function in patients with RCVS exhibited a unique dynamic evolution that was temporally coupled to different vascular indices and headache-related disabilities along the disease course. These findings may provide novel insights into the complex interactions between glymphatic transport, vasomotor control and pain modulation.

Effects of butylphthalide on cerebral vascular circulation, coagulation function, and neurological function in patients with acute severe ischemic stroke following intravenous thrombolysis: a preliminary study

Objective To analyze the effects of Butylphthalide on cerebral vascular circulation, coagulation function, and neurological function in patients with acute severe ischemic stroke following intravenous thrombolysis. Methods Clinical efficacy, cerebral vascular circulation indicators [anterior cerebral artery (ACA), middle cerebral artery (MCA), vertebral artery (VA) blood flow velocity], coagulation function indicators [prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen (FIB)], neurological function indicators [Activities of Daily Living (ADL) score. Results The total effective rate of treatment in the control group was 76.47%, while in the observation group, it was 96.08%, with the observation group showing a significantly higher total effective rate than the control group (p < 0.05). Before treatment, there was no significant difference in ACA, MCA, and VA blood flow velocity between the two groups (p > 0.05). However, after treatment, the ACA, MCA, and VA blood flow velocity in the observation group were significantly higher than those in the control group (p < 0.05). Before treatment, there was no significant difference in PT, APTT, TT, and FIB levels between the two groups (p > 0.05). Conclusion In patients with acute severe ischemic stroke undergoing intravenous thrombolysis, the addition of Butylphthalide to the treatment regimen yields favorable clinical outcomes. Compared to Alteplase alone, the addition of Butylphthalide further improves cerebral vascular circulation and coagulation function, promoting the recovery and reconstruction of neurological function in patients. Importantly, the addition of Butylphthalide does not increase the risk of adverse reactions, making it a safe and ideal option for clinical application.

Cerebral blood flow autoregulation assessment by correlation analysis between mean arterial blood pressure and transcranial doppler sonography or near infrared spectroscopy is different: A pilot study.

Recently, cerebral autoregulation indices based on moving correlation indices between mean arterial pressure (MAP) and cerebral oximetry (NIRS, ORx) or transcranial Doppler (TCD)-derived middle cerebral artery flow velocity (Mx) have been introduced to clinical practice. In a pilot study, we aimed to evaluate the validity of these indices using incremental lower body negative pressure (LBNP) until presyncope representing beginning cerebral hypoperfusion as well as lower body positive pressure (LBPP) with added mild hypoxia to induce cerebral hyperperfusion in healthy subjects. Five male subjects received continuous hemodynamic, TCD and NIRS monitoring. Decreasing levels of LBNP were applied in 5-minute steps until subjects reached presyncope. Increasing levels of LBPP were applied stepwise up to 20 or 25 mmHg. Normobaric hypoxia was added until an oxygen saturation of 84% was reached. This was continued for 10 minutes. ORx and Mx indices were calculated using previously described methods. Both Indices showed an increase > 0.3 indicating impaired cerebral autoregulation during presyncope. However, there was no significant difference in Mx at presyncope compared to baseline (p = 0.168). Mean arterial pressure and cardiac output decreased only in presyncope, while stroke volume was decreased at the last pressure level. Neither Mx nor ORx showed significant changes during LBPP or hypoxia. Agreement between Mx and ORx was poor during the LBNP and LBPP experiments (R2 = 0.001, p = 0.3339). Mx and ORx represent impaired cerebral autoregulation, but in Mx this may not be distinguished sufficiently from baseline. LBPP and hypoxia are insufficient to reach the upper limit of cerebral autoregulation as indicated by Mx and ORx.

Clinical efficacy analysis of butylphthalide combined with urinary kallidinogenase in treating chronic cerebral circulatory insufficiency.

To investigate the clinical effect of butylphthalide combined with urinary kallidinogenase in the treatment of chronic cerebral circulatory insufficiency (CCCI). A total of 102 CCCI patients admitted to our hospital from October 2020 to December 2021 were retrospectively enrolled in this study. According to the different therapeutic strategy, the patients were divided into combined group (treated with butylphthalide combined with urinary kallidinogenase, n=51) and butylphthalide group (treated with butylphthalide, n=51). Blood flow velocity and cerebral blood flow perfusion before and after treatment between the two groups were compared. The clinical efficacy and adverse events of the two groups were analyzed. After treatment, the effective rate of the combined group was significantly higher than the butylphthalide group (p=.015). Before treatment, the blood flow velocity of middle cerebral artery (MCA), vertebral artery (VA), basilar artery (BA) were comparable (p>.05, respectively), while after treatment, the blood flow velocity of MCA, VA, and BA in combined group were faster than those in butylphthalide group (p<.001, respectively). Before treatment, the relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), relative mean transmit time (rMTT) of the two groups were comparable (p>.05, respectively). After treatment, rCBF and rCBV in combined group were higher than those in butylphthalide group (p<.001, respectively), and rMTT in combined group was lower than that in butylphthalide group (p=.001). The rate of adverse events in the two groups were comparable (p=.558). Butylphthalide combined with urinary kallidinogenase can improve the clinical symptoms of CCCI patients, and the effect is promising, which is worthy of clinical application.

Sleep disordered breathing and its relation to stroke and pulmonary hypertension in children with sickle cell disease: a single-center cross-sectional study

Sleep disordered breathing (SDB) is a common underdiagnosed sequela of sickle cell disease (SCD) that has been linked to the frequency of vaso-occlusive crises. To determine the frequency of SDB in children with SCD and its association to SCD-related complications, thirty children and adolescents with SCD at their steady state underwent clinical, laboratory, and radiological assessment using transcranial duplex (TCD) and echo assessment of tricuspid regurge velocity (TRV). All participants had an overnight polysomnography after completing the modified STOP-Bang questionnaire. The mean age of the studied cohort was 10.2 years, with male: female ratio 1.7:1. Six children (20%) had high-risk for obstructive sleep apnea (OSA), while nine (30%) were at intermediate risk. Sleep apnea defined as apnea (AHI) > 1 event/hour was found among 18/30 (60%) subjects (14 males and 4 females). Children with AHI > 5 (moderate to severe OSA) had significantly higher TRV (p = 0.007) and left MCA flow velocity (p = 0.049) when compared to those with AHI < 5. Children with AHI > 5 were at higher risk of OSA according to the modified STOP-Bang questionnaire (p = 0.02). AHI positively correlated with TRV (r = 0.53, p = 0.003), right MCA flow velocity (r = 0.45, p = 0.013), and left MCA flow velocity (r = 0.55, p = 0.002), and negatively correlated to BMI-SDS (r = − 0.48, p = 0.008). The high frequency of OSA in the studied cohort with SCD and its association with increasing risk of PH and TCD changes highlights the importance of early detection and management of OSA in children with SCD.

Correlation between heart rate variability and cerebral autoregulation in septic patients.

Heart rate variability (HRV) may provide an estimation of the autonomous nervous system (ANS) integrity in critically ill patients. Disturbances of cerebral autoregulation (CAR) may share common pathways of ANS dysfunction. To explore whether changes in HRV and CAR index correlate in critically ill septic patients. Prospectively collected data on septic adult (> 18years) patients admitted into a mixed Intensive Care between February 2016 and August 2019 with a recorded transcranial doppler CAR assessment. CAR was assessed calculating the Pearson's correlation coefficient (i.e. mean flow index, Mxa) between the left middle cerebral artery flow velocity (FV), insonated with a 2-MHz probe, and invasive blood pressure (BP) signal, both recorded simultaneously through a Doppler Box (DWL, Germany). MATLAB software was used for CAR assessment using a validated script; a Mxa >0.3 was considered as impaired CAR. HRV was assessed during the same time period using a specific software (Kubios HRV 3.2.0) and analyzed in both time-domain and frequency domain methods. Correlation between HRV-derived variables and Mxa were assessed using the Spearman's coefficient. A total of 141 septic patients was studied; median Mxa was 0.35 [0.13-0.60], with 77 (54.6%) patients having an impaired CAR. Mxa had a significant although weak correlation with HRV time domain (SDNN, r=0.17, p=0.04; RMSSD, r=0.18, p=0.03; NN50, r=0.23, p=0.006; pNN50, r=0.23, p=0.007), frequency domain (FFT-HF, r=0.21; p=0.01; AR-HF, r=0.19; p=0.02), and non-linear domain (SD1, r=0.18, p=0.03) parameters. Impaired CAR patients had also all of these HRV-derived parameters higher than those with intact CAR. In this exploratory study, a potential association of ANS dysfunction and impaired CAR during sepsis was observed.

Evaluation of the changes in middle cerebral artery flow velocity related to different positions of patients during posterior fossa surgery.

This is a prospective observational study to evaluate the changes in middle cerebral artery flow velocities and cerebral perfusion pressure in the various positions used for posterior cranial fossa surgery and to correlate these changes with postoperative recovery characteristics and complications. Sixty patients were included in the study - 33 patients with CPA tumors were placed in the supine with head tilt position and the rest 27 with tumors in other locations of posterior fossa were placed in the prone position. The primary aim was to study the changes in middle cerebral artery blood flow velocity related to various positions of the patients used during posterior fossa surgery. The secondary aim was to compare the changes in pulsatility index, resistance index, and effective cerebral perfusion pressure in different position and to correlate these findings with postoperative recovery and the complications associated with these positions. The systolic and mean flow velocities were higher in the supine with head tilt group than the prone group after positioning and post repositioning, but these values were within normal limits, and the changes with positioning from baseline were comparable between the groups. Furthermore, these changes did not affect the effective cerebral perfusion pressure or the outcomes of the patients. The current results do not determine whether the supine with head tilt position is better than the prone position during posterior fossa surgery.

Post-reperfusion hyperperfusion after endovascular stroke treatment: a prospective comparative study of TCD versus MRI

BackgroundIncreased middle cerebral artery (MCA) blood flow velocities on transcranial duplex sonography (TCD) were recently reported in individual patients after successful mechanical thrombectomy (MT) and were related to intracranial hemorrhage...

Low Heart Rate Is Associated with Cerebral Pulsatility after TIA or Minor Stroke.

Beta-blockers are beneficial in coronary artery disease but less so in stroke prevention and dementia, potentially due to reduced heart rate (HR). Cerebral pulsatility is strongly associated with cerebral small vessel disease (SVD) and may be increased by lower diastolic pressures resulting from longer cardiac cycles. Patients 4-6 weeks after TIA or non-disabling stroke (Oxford Vascular Study) underwent 5 minutes continuous monitoring of blood pressure (BP), electrocardiogram (ECG), and middle cerebral artery flow velocity (transcranial ultrasound). Beat-to-beat relationships between HR, blood pressure and Gosling's pulsatility index (MCA-PI) are reported as beta-coefficients from general linear models for each individual. Across 759 patients, average MCA-PI during monitoring was associated with lower HR and diastolic BP (DBP) and greater systolic BP (SBP) (∆MCA-PI per 10 bpm/mmHg: -0.02, -0.04, 0.03, all p < 0.001), with HR particularly associated with low end-diastolic cerebral velocity (0.86, p=0.014). Beat-to-beat HR was strongly associated with concurrent low DBP and high SBP, potentially mediating the association with greater beat-to-beat cerebral pulsatility (average ∆MCA-PI vs HR/DBP/SBP unadjusted: -0.062, -0.052, 0.0092; adjusted for concurrent BP: -0.039, -0.11, 0.041). The beat-to-beat association between HR and MCA-PI increased with age, beta-blockers, arterial stiffness, low HR (age > 70 + HR < 65 vs age < 70 + HR > 65: -0.081 vs -0.024, interaction p < 0.001), and severe SVD on MRI (age > 70 + severe vs age < 70 + none: -0.087 vs -0.047, interaction p=0.03), with interactions between age, severe SVD, and low HR synergistically increasing MCA-PI. Low HR is associated with greater cerebral pulsatility in patients with SVD, potentially mediated by lower diastolic blood flow and representing a novel potential treatment target. ANN NEUROL 2022;92:909-920.

Effect of a standardized maternal meal on fetal middle cerebral artery Doppler indices: A single-blinded crossover study.

ObjectiveMeasures of Doppler blood flow velocity profiles are an integral part of monitoring fetal well-being during pregnancy. These examinations are performed at different times of the day and at different maternal meal states. In uncomplicated pregnancies, we assessed the effect of a standardized maternal meal on middle cerebral artery (MCA) and umbilical artery (UA) Doppler blood flow velocity pulsatility indices (PIs) and MCA peak systolic velocity (PSV).MethodsIn this prospective single-blinded crossover study 25 healthy women were examined at 36 weeks of pregnancy. The first examination was performed in the morning following overnight fast, and repeated after extended fast (state A), and after a standard breakfast meal (state B).ResultsIrrespective of maternal prandial status, the MCA-PI values were lower in the 2nd compared to the 1st examination (-0.187; p = 0.071, and -0.113; p = 0.099, state A and B, respectively). Compared to the values in the 1st examination, the UA-PI values, were higher after extended fast (0.014; p = 0.436), and lower post-prandially (-0.036; p = 0.070). The difference (state B minus state A) between the meal states were not significant (0.074; p = 0.487 and -0.050; p = 0.058, for MCA-PI and UA-PI, respectively). Adjusting for the possible influence of fetal heart rate on MCA-PI and UA-PI, the differences between meal states remained non-significant (p = 0.179, p = 0.064, respectively). The MCA-PSV values increased after the meal (6.812; p = 0.035), whereas no increase was observed following extended fast (0.140; p = 0.951). The difference in MCA-PSV values between the two meal states was not significant (6.672; p = 0.055).ConclusionOur results demonstrate possible diurnal variations in MCA-PI and UA-PI, with and without adjustment for fetal heart rate, that seem to be unaffected by maternal meal intake in healthy pregnancies.

Cerebral Autoregulation in Healthy Term Newborns: Brief Report

Cerebral autoregulation is a homeostatic process that maintains cerebral blood flow (CBF) across a range of mean arterial pressures (MAPs). Cerebral autoregulation can be impaired in pathologic systemic and neurological conditions and can lead to cerebral hypoperfusion or cerebral hyperperfusion from low and high MAPs, respectively. 1 Obrist W.D. Gennarelli T.A. Segawa H. Dolinskas C.A. Langfitt T.W. Relation of cerebral blood flow to neurological status and outcome in head-injured patients. J Neurosurg. 1979; 51: 292-300 Crossref PubMed Scopus (116) Google Scholar Little is known about the maturation of cerebral autoregulation after birth or whether there are sex differences in CBF at birth. One study of 16 term neonates without congenital heart disease tested autoregulation using cerebral oximeter monitoring with tilt testing and reported that cerebral autoregulation was intact between three and 10 days. 2 Tran N.N. Kumar S.R. Hodge F.S. Macey P.M. Cerebral autoregulation in neonates with and without congenital heart disease. Am J Crit Care. 2018; 27: 410-416https://doi.org/10.4037/ajcc2018672 Crossref PubMed Scopus (11) Google Scholar Sex differences in CBF have been observed in older ages. Similar to healthy adolescents aged 10 to 16 years and healthy adults, prepubertal girls between four and eight years have higher middle cerebral and basilar artery flow velocities than age-matched boys. 3 Vavilala M.S. Kincaid M.S. Muangman S.L. Suz P. Rozet I. Lam A.M. Gender differences in cerebral blood flow velocity and autoregulation between the anterior and posterior circulations in healthy children. Pediatr Res. 2005; 58: 574-578 Crossref PubMed Scopus (92) Google Scholar ,4 Tontisirin N. Muangman S.L. Suz P. et al. Early childhood gender differences in anterior and posterior cerebral blood flow velocity and autoregulation. Pediatrics. 2007; 119: e610-e615 Crossref PubMed Scopus (62) Google Scholar Studies report that both healthy boys and girls aged between four and 16 years have intact cerebral autoregulation and children aged two to six years have a lower limit of autoregulation (LLA) similar to adolescents and adults. 3 Vavilala M.S. Kincaid M.S. Muangman S.L. Suz P. Rozet I. Lam A.M. Gender differences in cerebral blood flow velocity and autoregulation between the anterior and posterior circulations in healthy children. Pediatr Res. 2005; 58: 574-578 Crossref PubMed Scopus (92) Google Scholar , 4 Tontisirin N. Muangman S.L. Suz P. et al. Early childhood gender differences in anterior and posterior cerebral blood flow velocity and autoregulation. Pediatrics. 2007; 119: e610-e615 Crossref PubMed Scopus (62) Google Scholar , 5 Vavilala M.S. Lee L.A. Lam A.M. The lower limit of cerebral autoregulation in children during sevoflurane anesthesia. J Neurosurg Anesthesiol. 2003; 15: 307-312 Crossref PubMed Scopus (78) Google Scholar This finding means that infants and young children have less cerebral autoregulatory reserve (difference between MAP and LLA) than older children. 5 Vavilala M.S. Lee L.A. Lam A.M. The lower limit of cerebral autoregulation in children during sevoflurane anesthesia. J Neurosurg Anesthesiol. 2003; 15: 307-312 Crossref PubMed Scopus (78) Google Scholar However, girls aged four to 16 years have higher normative autoregulatory indices of the basilar artery compared with age-matched boys and healthy boys aged four to 16 years have higher normative autoregulatory indices of the middle cerebral artery (MCA) compared with healthy girls; the reasons for these differences are not well understood. 3 Vavilala M.S. Kincaid M.S. Muangman S.L. Suz P. Rozet I. Lam A.M. Gender differences in cerebral blood flow velocity and autoregulation between the anterior and posterior circulations in healthy children. Pediatr Res. 2005; 58: 574-578 Crossref PubMed Scopus (92) Google Scholar ,4 Tontisirin N. Muangman S.L. Suz P. et al. Early childhood gender differences in anterior and posterior cerebral blood flow velocity and autoregulation. Pediatrics. 2007; 119: e610-e615 Crossref PubMed Scopus (62) Google Scholar In clinical practice, hypotension is commonly defined in relation to gestational age (GA), and hypotension is common in critically ill neonates. 6 Dilli D. Soylu H. Tekin N. Neonatal hemodynamics and management of hypotension in newborns. Turk Pediatri Ars. 2018; 53: S65-S75 Crossref PubMed Scopus (10) Google Scholar Obtaining normative data for female and male newborns is a requisite for further understanding CBF and cerebral autoregulation and optimizing cerebral perfusion in critically ill neonates. We explored CBF velocity and cerebral autoregulation of the anterior cerebral circulation among healthy term newborns.

Physiological Mechanisms and Significance of Intracranial B Waves.

ObjectiveRecently published studies have described slow spontaneous cerebral blood flow (CBF) and cerebrospinal fluid (CSF) oscillations measured by magnetic resonance imaging (MRI) as potential drivers of brain glymphatic flow, with a similar frequency as intracranial B-waves. Aiming to establish the relationship between these waveforms, we performed additional analysis of frequency and waveform parameters, of our previously published transcranial Doppler (TCD) and intracranial pressure (ICP) recordings of intracranial B waves, to compare to published MRI frequency measurements of CBF and CSF slow oscillations.Patients and MethodsWe analyzed digital recordings of B waves in 29 patients with head injury, including middle cerebral artery (MCA) flow velocity (FV), ICP, end tidal CO2, and arterial blood pressure (ABP). A subset of these recordings demonstrated high B wave activity and was further analyzed for parameters including frequency, interaction, and waveform distribution curve features. These measures were compared to published similar measurements of spontaneous CBF and CSF fluctuations evaluated using MRI.ResultsIn patients with at least 10% amplitude B wave activity, the MCA blood flow velocity oscillations comprising the B waves, had a maximum amplitude at 0.0245 Hz, and time derivative a maximum amplitude at 0.035 Hz. The frequency range of the B waves was between 0.6–2.3 cycles per min (0.011-0.038 Hz), which is in the same range as MRI measured CBF slow oscillations, reported in human volunteers. Waveform asymmetry in MCA velocity and ICP cycles during B waves, was also similar to published MRI measured CBF slow oscillations. Cross-correlation analysis showed equivalent time derivatives of FV vs. ICP in B waves, compared to MRI measured CBF slow oscillations vs. CSF flow fluctuations.ConclusionsThe TCD and ICP recordings of intracranial B waves show a similar frequency range as CBF and CSF flow oscillations measured using MRI, and share other unique morphological wave features. These findings strongly suggest a common physiological mechanism underlying the two classes of phenomena. The slow blood flow and volume oscillations causing intracranial B waves appear to be part of a cascade that may provide a significant driving force for compartmentalized CSF movement and facilitate glymphatic flow.

Cerebral Augmentation Effect Induced by External Counterpulsation Is Not Related to Impaired Dynamic Cerebral Autoregulation in Ischemic Stroke.

Background and PurposeDynamic cerebral autoregulation is impaired after ischemic stroke. External counterpulsation (ECP) augments the cerebral blood flow of patients with ischemic stroke by elevation of blood pressure (BP). We aimed to investigate if cerebral augmentation effects during ECP were associated with impaired dynamic cerebral autoregulation in patients after acute ischemic stroke.MethodsForty patients with unilateral ischemic stroke and large artery atherosclerosis in the anterior circulation territory within 7 days from symptom onset and eighteen healthy controls were recruited. We monitored changes in mean flow velocity over both middle cerebral arteries (MCA) by transcranial Doppler (TCD) before, during, and immediately after ECP. Cerebral augmentation index was MCA mean flow velocity increase in percentage during ECP compared with baseline to evaluate the augmentation effects of ECP. Spontaneous arterial BP and cerebral blood flow velocity in both bilateral MCAs were recorded using a servo-controlled plethysmograph and TCD, respectively. Transfer function analysis was used to derive the autoregulatory parameters, including phase difference (PD), and gain.ResultsThe cerebral augmentation index in patients with stroke was significantly higher on both the ipsilateral and contralateral sides than that in controls, while the PD in patients with stroke was significantly lower on both sides than those in controls (all P < 0.05). The cerebral augmentation index did not correlate with PD and gain on either the ipsilateral or contralateral side of patients with stroke or in controls (all P > 0.05). The cerebral augmentation index of patients with stroke was significantly related to mean BP change on the ipsilateral side (R2 = 0.108, P = 0.038).ConclusionThe degree of ECP-induced cerebral augmentation effects as measured by the cerebral augmentation index did not correlate with the magnitude of impaired dynamic cerebral autoregulation.

Cerebral Blood Flow in Healthy Subjects with Different Hypnotizability Scores.

Hypnotizability is a cognitive trait associated with differences in the brachial artery flow-mediated dilatation of individuals with high hypnotizability (highs) and low hypnotizability scores (lows). The study investigated possible hypnotizability-related cerebrovascular differences. Among 24 healthy volunteers, the Stanford Hypnotic Susceptibility Scale Form A identified 13 medium-to-lows (med-lows), 11 medium-to-highs (med-highs), and 1 medium hypnotizable. Hypnotizability did not influence the significant changes produced by the trail making task (TMT), mental arithmetic task (MAT), hyperventilation (HVT), and rebreathing (RBT) on heart rate (HR), arterial blood pressure (ABP), and partial pressure of end-tidal CO2 (PETCO2), but moderated the correlations between the changes occurring during tasks with respect to basal conditions (Δ) in ABP and PETCO2 with middle cerebral artery flow velocity (MCAv). In HVT, med-lows exhibited a significant correlation between ΔMCAv and ΔPETCO2, and med-highs showed a significant correlation between ΔABP and ΔMCAv. Cerebrovascular reactivity (CVR) and conductance (ΔCVCi) were significantly correlated with ΔMCAv only in med-lows during HVT and RBT. For the first time, cerebrovascular reactivity related to hypnotizability was investigated, evidencing different correlations among hemodynamic variables in med-highs and med-lows.

Relation of middle cerebral artery flow velocity and risk of cognitive decline: A prospective community-based study

ObjectivesHemodynamic parameters measured by the Transcranial Doppler Ultrasound (TCD) are related to cognitive impairment in many cross-sectional studies, but the longitudinal evidence is scarce. In this study, we aim to verify the association between flow velocity of Middle Cerebral Artery (MCA) and the longitudinal cognitive decline in community dwelling older adults. Materials and methodsParticipants were administered TCD examination at the baseline. The Peak Systolic Velocity (PSV), Mean Flow Velocity (MFV), and Pulsatility Index (PI) of MCA segments on left middle (LmMCA), left proximal (LpMCA), right middle (RmMCA), and right proximal (RpMCA) were obtained. Mini-mental state examination (MMSE) were conducted at both baseline and follow-up. ResultsOne hundred and thirteen participants without dementia were followed up for 6.3 years in average. The mean annual rate of decline in the MMSE score was 0.15 (min to max: −1.0 to 1.2). LpMCA PSV (β = −0.0034, r = −0.231, P = 0.022) and LpMCA MFV (β = −0.0049, r = −0.217, P = 0.031) were inversely associated with annual rate of decline in the MMSE score after adjusting for age, gender, education year, APOE ε4, obesity, hypertension, diabetes mellitus, stroke, and coronary heart disease. ConclusionsBlood flow velocity of left proximal MCA was inversely related to global cognitive decline. Cerebral blood flow velocity may impact the cognitive function.

Cardiac Stroke Volume Index Is Associated With Early Neurological Improvement in Acute Ischemic Stroke Patients.

Early neurological improvement as assessed with the NIH stroke scale (NIHSS) at 24 h has been associated with improved long-term functional outcomes following acute ischemic stroke (AIS). Cardiac dysfunction is often present in AIS, but its association with outcomes is incompletely defined. We performed a pilot study to evaluate the association between non-invasively measured cardiac parameters and 24-h neurological improvement in prospectively enrolled patients with suspected AIS who presented within 12 h of symptom-onset and had an initial systolic blood pressure>140 mm Hg. Patients receiving thrombolytic therapy or mechanical thrombectomy were excluded. Non-invasive pulse contour analysis was used to measure mean arterial blood pressure (MAP), cardiac stroke volume index (cSVI), cardiac output (CO) and cardiac index (CI). Transcranial Doppler recorded mean middle cerebral artery flow velocity (MFV). We defined a decrease of 4 NIHSS points or NIHSS ≤ 1 at 24-h as neurological improvement. Of 75 suspected, 38 had confirmed AIS and did not receive reperfusion therapy. Of these, 7/38 (18.4%) had neurological improvement over 24 h. MAP was greater in those without improvement (108, IQR 96–123 mm Hg) vs. those with (89, IQR 73–104 mm Hg). cSVI, CO, and MFV were similar between those without and with improvement: 37.4 (IQR 30.9–47.7) vs. 44.7 (IQR 42.3–55.3) ml/m2; 5.2 (IQR 4.2–6.6) vs. 5.3 (IQR 4.7–6.7) mL/min; and 39.9 (IQR 32.1–45.7) vs. 34.4 (IQR 27.1–49.2) cm/s, respectively. Multivariate analysis found MAP and cSVI as predictors for improvement (OR 0.93, 95%CI 0.85–0.98 and 1.14, 95%CI 1.03–1.31). In this pilot study, cSVI and MAP were associated with 24-h neurological improvement in AIS.

Transcranial Doppler findings in reversible cerebral vasoconstriction syndrome.

Reversible cerebral vasoconstriction syndrome (RCVS) is a syndrome characterized by reversible segmental vasoconstriction of cerebral arteries. Digital subtraction and noninvasive angiograms are typically used to detect vasospasm; however, due to the dynamic nature of RCVS these tests are often negative initially and may need to be repeated multiple times. Transcranial Doppler (TCD) offers many advantages as it is a noninvasive and nonradiating modality. Studies investigating its diagnostic utility for capturing vasospasm and studying temporal evolution of RCVS are limited. We conducted a retrospective analysis on all patients admitted with suspected RCVS from 2009 to 2014 to a single center at Jackson Memorial Hospital. We identified 9 patients (88.9% women, age 46.6 ± 13.5 years) who met diagnostic criteria for RCVS. All patients presented with headache, 5 developed nonaneurysmal subarachnoid hemorrhage, 5 developed ischemic stroke, and 1 developed posterior reversible encephalopathy syndrome. At initial TCD, 8 patients had increased flow velocities in at least one large intracranial artery and ultimately all patients had abnormal middle cerebral artery flow velocity over the course of RCVS. We found that the number of vessels with abnormal velocities increases gradually and peaks between 13 and 14 days after first symptom onset. Finally, mean flow velocity of affected vessels also increases around the same time frame and normalizes at 60 days. In this case series, we found TCD to be useful in detecting vasospasm and monitoring the temporal evolution of RCVS. TCD could be a helpful clinical tool to diagnose and monitor RCVS.