Mean Cerebral Blood Flow Velocity Research Articles

Efficacy and safety of combining ginkgolide diterpene glucosamine injection with dual antibodies in elderly patients with acute ischemic stroke

Purpose: To investigate the clinical effects and safety of ginkgo biloba diterpene lactone glucosamine injection, combined with dual antibiotic therapy for acute ischemic stroke in elderly individuals within a hyper thrombolytic time window. 
 Methods: 100 elderly patients with acute ischemic stroke at Changsha First Hospital, Changsha, China from March 2022 to March 2023 were randomly and equally assigned to study and control groups (50 patients each). Study group received aspirin and clopidogrel, while control group received ginkgo biloba diterpene lactone glucosamine injection along with dual antibodies. Clinical efficacy, National Institutes of Health Stroke Scale (NIHSS) score, Instrumental Activities of Daily Living (IADL) score, cerebral hemodynamics, and safety were compared between the two groups. 
 Results: There was no significant difference in effective rate between the two groups (p > 0.05). However, following treatment, study group showed superior NIHSS and IADL scores compared to control group, with greater statistical significance as the disease progressed. Doppler ultrasound revealed that study group had smaller Pulsatility index (PI) values and larger mean cerebral artery blood flow velocity (Vm), and systolic value (Vs) compared to control group (p < 0.05). In study group, three adverse reactions were reported (gastrointestinal discomfort, abnormal liver/kidney function, and skin itching), whereas the control group experienced five adverse reactions (gastrointestinal discomfort, abnormal liver/kidney function, dizziness, and skin itching). 
 Conclusion: The combination of Ginkgo biloba diterpene lactone glucosamine injection and dual antibodies in elderly individuals with acute ischemic stroke within a super thrombolytic time window enhances intracerebral blood flow levels, effectively promotes neurological recovery, improves daily living abilities, and safety. Further research is needed to elucidate the exact pathways involved.

Comparable dynamic cerebral autoregulation and neurovascular coupling of the posterior cerebral artery between healthy men and women.

Most studies focus on dynamic cerebral autoregulation (dCA) in the middle cerebral artery (MCA), and few studies investigated neurovascular coupling (NVC) and dCA in the posterior cerebral artery (PCA). We investigated NVC and dCA of the PCA in healthy volunteers to identify sex differences. Thirty men and 30 age-matched women completed dCA and NCV assessments. The cerebral blood flow velocity (CBFV) and mean arterial pressure were evaluated using transcranial Doppler ultrasound and a servo-controlled plethysmograph, respectively. The dCA parameters were analyzed using transfer function analysis. The NCV was evaluated by eyes-open and eyes-closed (24 s each) periodically based on voice prompts. The eyes-open visual stimulation comprised silent reading of Beijing-related tourist information. The PCA gain was lower than that of the MCA in all frequency ranges (all p < 0.05). Phase was consistent across the cerebrovascular territories. The cerebrovascular conductance index (CVCi) and mean CBFV (MV) of the PCA were significantly higher during the eyes-open than eyes-closed period (CVCi: 0.50 ± 0.12 vs. 0.38 ± 0.10; MV: 42.89 ± 8.49 vs. 32.98 ± 7.25, both p < 0.001). The PCA dCA and NVC were similar between the sexes. We assessed two major mechanisms that maintain cerebral hemodynamic stability in healthy men and women. The visual stimulation-evoked CBFV of the PCA was significantly increased compared to that during rest, confirming the activation of NVC. Men and women have similar functions in PCA dCA and NCV.

Abstract 55: Cerebral Autoregulatory Curves in Postpartum Individuals With and Without Preeclampsia

Introduction: Risk of maternal stroke is higher in patients with preeclampsia (PEC), with the highest risk seen in those with chronic hypertension with superimposed preeclampsia (siPEC). Most strokes occur postpartum. Changes in cerebral autoregulation (CA) could contribute to elevated postpartum stroke risk. We describe CA curves in postpartum patients with no hypertension, PEC and siPEC. Methods: We prospectively recruited postpartum patients with and without PEC and measured 10-minute continuous mean arterial pressure (MAP) and cerebral blood flow velocity (CBFV) with finger plethysmography and transcranial Doppler within 1 week of delivery. We generated polynomial S-curves to derive limits of CA, CA plateaus (defined as slope &lt; 0.15), and mean and minimum slopes between CA limits. We calculated Pearson correlation coefficients (Mx) between normalized MAP and CBVF; Mx &gt; 0.3 indicates high MAP-CBFV correlation, suggesting impaired CA. Results: CA curves were produced from 71 patients (28% normotensive, 42% PEC, 30% siPEC). Group means for MAP were higher in those with PEC and siPEC (normotensive 72 mmHg, PEC 88, siPEC 87 [p=0.001]). CA was preserved in all groups, with Mx nadirs below 0.3 (Figure). The normotensive group demonstrated a wide, flat plateau in the S-curve (minimum slope 0.02). In the PEC group, we observed a narrower and slightly steeper autoregulatory plateau (minimum slope 0.05). The siPEC group displayed the narrowest and steepest plateau (minimum slope 0.15). Conclusion: In conclusion, in our sample of postpartum patients with normotension, PEC and siPEC, we observed a gradient in CA plateau range and slope. Compared with the normotensive group, the PEC and siPEC groups had progressively narrower and steeper CA plateaus, suggesting a more limited CA range and diminished CA efficacy. Future studies should investigate whether sustained MAP outside CA limits contributes to adverse maternal outcomes, particularly in those with siPEC.

Abstract WP121: Cerebral Hemodynamics in the First Week Postpartum in Healthy Women and Women With Preeclampsia

Objective: Standard adult normative data for transcranial Doppler (TCD)-based cerebral hemodynamic measures, such as mean and peak cerebral blood flow velocity (mCBFV, pCBFV), are used to identify pathological conditions such as postpartum angiopathy. However, little is known about cerebral hemodynamics during the early postpartum period, particularly in patients with preeclampsia (PEC). We characterized cerebral hemodynamics using TCD in the first week postpartum in patients with and without PEC. Methods: We prospectively recruited women with PEC and normotensive pregnant women delivering at an urban academic medical center. We measured CBFV in the bilateral middle cerebral arteries with TCD and calculated systolic mCBFV and pCBFV as well as pulsatility index (PI) and PI-derived noninvasive intracranial pressure (nICP). We compared systolic mCBFV and pCBFV between postpartum women with and without PEC, and historical data from non-pregnant young adult female controls. Results: Subjects were 51 women with PEC, 19 normotensive postpartum women, and 28 non-pregnant historical controls. In the PEC group, median mCBFV was 75.0 cm/s (IQR 65.2-99.1) and median pCBFV was 106.9 cm/s (IQR 92.7-130.8). In the normotensive postpartum group, median mCBFV was 77.1 cm/s (IQR 66.0-92.3) and median pCBFV was 107.9 cm/s (IQR 96.6-127.4). In the non-pregnant female control group, median mCBFV was 62.0 cm/s (IQR 48.5-67.9) and median pCBFV was 83.6 cm/s (IQR 69.3-95.2) (p&lt;0.0001 for mean and peak 3-way comparisons; see Figure). PI and nICP were within normal range in both postpartum groups and did not differ significantly between groups. Conclusion: Postpartum women with and without PEC had mCBFV and pCBFV significantly higher than non-pregnant controls, and many fell outside the standard normal range for healthy adults, but PI and nICP were within normal range. Standard ranges of CBFV for healthy adults may not apply in the postpartum period.

The effects of pulsatile versus nonpulsatile flow on cerebral pulsatility index, mean flow velocity at the middle cerebral artery, regional cerebral oxygen saturation, cerebral gaseous microemboli counts, and short-term clinical outcomes in patients undergoing congenital heart surgery

ObjectiveThe objective of this retrospective review was to evaluate whether or not pulsatile flow improves cerebral hemodynamics and clinical outcomes in pediatric congenital cardiac surgery patients. MethodsThis retrospective study included 284 pediatric patients undergoing congenital cardiac surgery with cardiopulmonary bypass support utilizing nonpulsatile (n = 152) or pulsatile (n = 132) flow. Intraoperative cerebral gaseous microemboli counts, pulsatility index, and mean blood flow velocity at the right middle cerebral artery were assessed using transcranial Doppler ultrasound. Clinical outcomes were compared between groups. ResultsPatient demographics and cardiopulmonary bypass characteristics between groups were similar. Although the pulsatility index during aortic crossclamping was consistently higher in the pulsatile group (P < .05), a significant degree of pulsatility was also observed in the nonpulsatile group. No significant differences in mean cerebral blood flow velocity, regional cerebral oxygen saturation, or gaseous microemboli counts were observed between the perfusion modality groups. Clinical outcomes, including intubation duration, intensive care unit and hospital length of stay, and mortality within 180 days were similar between groups. ConclusionsAlthough the pulsatility index was greater in the pulsatile group, other measures of intraoperative cerebral perfusion and short-term outcomes were similar to the nonpulsatile group. These findings suggest that while pulsatile perfusion represents a safe modality for cardiopulmonary bypass support, its use may not translate into detectably superior clinical outcomes.

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.

Stellate Ganglion Block and Intraarterial Spasmolysis in Patients with Cerebral Vasospasm: A Retrospective Cohort Study

BackgroundIn patients with symptomatic cerebral vasospasm (CV) following aneurysmal subarachnoid hemorrhage who do not respond to medical therapy, urgent treatment escalation has been suggested to be beneficial for brain tissue at risk. In our routine clinical care setting, we implemented stellate ganglion block (SGB) as a rescue therapy with subsequent escalation to intraarterial spasmolysis (IAS) with milrinone for refractory CV.MethodsIn this retrospective analysis from 2012 to 2021, patients with CV following aneurysmal subarachnoid hemorrhage who received an SGB or IAS were identified. Patients were assessed through neurological examination and transcranial Doppler. Rescue therapy was performed in patients with mean cerebral blood flow velocity (CBFV) ≥ 120 cm/s and persistent neurological deterioration/intubation under induced hypertension. Patients were reassessed after therapy and the following day. The Glasgow Outcome Scale was assessed at discharge and 6-month follow-up.ResultsA total of 82 patients (mean age 50.16 years) with 184 areas treated with SGB and/or IAS met the inclusion criteria; 109 nonaffected areas were extracted as controls. The mean CBFV decrease in the middle cerebral artery on the following day was − 30.1 (± 45.2) cm/s with SGB and − 31.5 (± 45.2) cm/s with IAS. Mixed linear regression proved the significance of the treatment categories; other fixed effects (sex, age, aneurysm treatment modality [clipping or coiling], World Federation of Neurological Surgeons score, and Fisher score) were insignificant. In logistic regression, the presence of cerebral infarction on imaging before discharge from the intensive care unit (34/82) was significantly associated with unfavorable outcomes (Glasgow Outcome Scale ≤ 3) at follow-up.ConclusionsStellate ganglion block and IAS decreased CBFV the following 24 h in patients with CV. We suggest SGB alone for patients with mild symptomatic CV (CBFV < 180 cm/s), while subsequent escalation to IAS proved to be beneficial in patients with refractory CV and severe CBFV elevation (CBFV ≥ 180 cm/s).

Pre and Post-Hemodialysis Cerebral Blood Flow Velocity in Patients With End-Stage Renal Disease.

This study assessed the consequences of hemodialysis (HD) on hemodynamic parameters of cerebral circulation by measuring middle cerebral artery blood flow velocities using transcranial Doppler ultrasound before and after a single dialysis session in patients with end-stage renal disease (ESRD). Fifty clinically stable patients with ESRD undergoing HD and 40 healthy controls were recruited for the study. Blood pressure, heart rate, and body weight were measured. Transcranial Doppler ultrasound evaluations and blood analyses were performed immediately before and after a single dialysis session. The mean cerebral blood flow velocities (CBFVs) in the ESRD patients before HD was 65 ± 17 cm/second and did not differ from that of the normal controls (64 ± 14 cm/s) (P = 0.735). The postdialysis CBFV also did not differ from that of the controls (P = 0.054). Compensatory cerebral autoregulation and chronic adjustment to therapy may be the reason for the nondeviation of the CBFV values from normality observed in both sessions.

Early stellate ganglion block for improvement of postoperative cerebral blood flow velocity after aneurysmal subarachnoid hemorrhage: results of a pilot randomized controlled trial.

Stellate ganglion block (SGB) is a commonly used sympathetic nerve block technique that may have benefits for patients with aneurysmal subarachnoid hemorrhage (aSAH) in the early stage. Cerebral vasospasm (CVS), one of the most common complications of aSAH, is accompanied by an abnormal increase in cerebral blood flow velocity (CBFV) and neurological dysfunction. In this pilot study the authors sought to determine the feasibility of early SGB for CVS in aSAH patients by observing the incidence of symptomatic CVS. Prior to receiving surgical treatment, patients with aSAH were randomly assigned to the SGB group or the non-SGB group. The primary outcome was the incidence of symptomatic CVS within 14 ± 2 days after the onset of aSAH. As a higher CBFV is often associated with CVS and a poor prognosis, the mean CBFV of the middle cerebral artery was observed immediately after surgery and on postoperative days 1, 2, 3, 5, and 7. Other secondary outcomes included transcranial Doppler (TCD)/CTA-type CVS, delayed cerebral ischemia during hospitalization, new cerebral infarction within 3 months, adverse events (AEs), and clinical prognosis. Symptomatic CVS occurred in 40% of patients in the non-SGB group and in 20% in the SGB group (RR 0.50, 95% CI 0.22-1.16). Continuous TCD sonography revealed that the postoperative mean CBFV was lower in the SGB group than in the non-SGB group (F = 3.608, p = 0.02). In addition, the percentages of patients with CVS evaluated by TCD (TCD-CVS) and total new infarctions within 3 months were also significantly lower than those in patients with CVS (TCD-CVS 36.7% vs 70%, RR 0.52, 95% CI 0.31-0.89, and total new infarctions 26.7% vs 53.3%, RR 0.50, 95% CI 0.25-0.99). In terms of AEs and mortality, there were no significant differences between the two groups. This pilot study demonstrated for the first time, to the authors' knowledge, that early SGB is feasible and has the potential to reduce the risk of CVS and improve the prognosis of aSAH. This method may be a new treatment for patients with aSAH that may have more advantages than traditional therapeutic drugs and is worth further study. Clinical trial registration no.: NCT04691271 (ClinicalTrials.gov).

Abstract Number ‐ 213: Single Center Experience of Intrathecal Nicardipine Use in The Treatment of Vasospasm‐ Lessons Learned

Introduction Symptomatic cerebral vasospasm and delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage leads to significant morbidity and mortality. Intrathecal (IT) nicardipine has been shown to improve outcome and reduce DCIin retrospective cohort studies1. Ecological validity of such reported conclusions may be a real‐world test of the efficacy of the proposed treatment.We sought to study our limited experience with this treatment modality in our cohort, in order to potentially inform our practice in treating vasospasm. Methods Retrospective case series of all patients who received IT nicardipine for the treatment of cerebral vasospasm from 2016 to 2021 at our University Hospital. Demographics, risk factors, clinical course and outcomes were analyzed. Results In addition to standard of care treatments and interventions, 12 patients received intrathecal nicardipine during the study period. IT nicardipine was given at doses of 2 mg every 8 hrs. Linear regression was conducted and found that IT nicardipine was associated with a reduction of the mean cerebral blood flow velocity of 16% on average. Among 12 patients, 5 patients had in‐hospital mortality; 4 out of these 5 patients developed in‐hospital DCI. Age (p 0.017), history of hypertension(HTN) (p 0.0007) were significant predictors for in‐hospital mortality. 6 patients developed DCI: mFisher scale (p 0.03), admission GCS (p 0.000998), vasopressor requirement to maintain target pressure (p 0.04) were significant predictors for developing DCI. Only 1 patient was diagnosed with bacterial ventriculitis (positive CSF culture). 80% (n = 5) patients had a favorable functional outcome (mRS≤2) at 90 days. Conclusions Our experience does not conform to the reported outcomes in a much larger patient cohort1. Nonetheless, the choice of this treatment on a case‐by‐case basis somewhat has led to rendering it as a salvage treatment at our center. In our cohort we found significant mortality rate, with age and HTN as predictive factors for in‐hospital mortality, and mFisher scale, admission GCS and vasopressor usage as predictors for DCI development. These results can be difficult to interpret, especially that the use of IT nicardipine was in only few selected patients with initial comorbidities potentially confounding the high mortality and morbidity in our cohort. Intrathecal nicardipine treatment without a well‐vetted protocol with clear inclusion and exclusion criteria can potentially misinform the practice style and lead to early abandonment of this promising therapy as part of our armamentarium. Thus, it is important to develop a standardized protocol with participation of all stakeholders of neurosurgery, neurocritical care, vascular neurology, pharmacy, and patient/family input before deploying in clinical practice on institutional level. Such protocols allow for a pilot study and more contextual prospective assessment of outcomes.

Comparison of discretization strategies for the model-free information-theoretic assessment of short-term physiological interactions

This work presents a comparison between different approaches for the model-free estimation of information-theoretic measures of the dynamic coupling between short realizations of random processes. The measures considered are the mutual information rate (MIR) between two random processes X and Y and the terms of its decomposition evidencing either the individual entropy rates of X and Y and their joint entropy rate, or the transfer entropies from X to Y and from Y to X and the instantaneous information shared by X and Y. All measures are estimated through discretization of the random variables forming the processes, performed either via uniform quantization (binning approach) or rank ordering (permutation approach). The binning and permutation approaches are compared on simulations of two coupled non-identical Hènon systems and on three datasets, including short realizations of cardiorespiratory (CR, heart period and respiration flow), cardiovascular (CV, heart period and systolic arterial pressure), and cerebrovascular (CB, mean arterial pressure and cerebral blood flow velocity) measured in different physiological conditions, i.e., spontaneous vs paced breathing or supine vs upright positions. Our results show that, with careful selection of the estimation parameters (i.e., the embedding dimension and the number of quantization levels for the binning approach), meaningful patterns of the MIR and of its components can be achieved in the analyzed systems. On physiological time series, we found that paced breathing at slow breathing rates induces less complex and more coupled CR dynamics, while postural stress leads to unbalancing of CV interactions with prevalent baroreflex coupling and to less complex pressure dynamics with preserved CB interactions. These results are better highlighted by the permutation approach, thanks to its more parsimonious representation of the discretized dynamic patterns, which allows one to explore interactions with longer memory while limiting the curse of dimensionality.

A survey of intracranial blood flow velocity in thalassemia intermedia in Khuzestan Province, Iran

Background: Beta-thalassemia intermedia (BTI) is a type of hemoglobinopathy with an increased risk of cerebrovascular accidents, and transcranial cerebral Doppler ultrasonography (TCD) through determining the mean cerebral blood flow velocity (CBFV) can serve to predict the risk of a developing stroke. This study aims to compare patients with beta-thalassemia intermedia and healthy individuals in terms of the cerebral blood flow velocity.&#x0D; Materials and Methods: This research was a case control study on 35 BTI patients and 25 healthy subjects. The patients were categorized into three age groups including 7-10, 11-15 and 16-20 years old. The mean CBFVs were compared between the two groups. The factors of age, gender, serum ferritin level, hemoglobin level, spleen size, thrombocytosis, and thalassemia genotypes were evaluated for their effects on CBFVs.&#x0D; Results: Mean CBFVs were significantly higher in all the intracranial arteries of BTI patients compared to normal subjects (p-value &lt; 0.05). The hemoglobin levels showed a negative correlation between the left and right vertebral arteries of BTI patients in terms of blood flow velocity (p-value &lt; 0.05). The mean CBFVs in the left vertebral and basilar arteries were negatively correlated to age in BTI. There was no correlation among ferritin level, thrombocytosis, splenomegaly, splenectomy, XmnI polymorphism, and cerebral blood flow velocity in the BTI patients group (p-value &gt; 0.05).&#x0D; Conclusion: This study showed that cerebral blood flow velocities of BTI patients were higher than normal control group. In addition, CBFVs were not affected by factors such as gender, serum ferritin, platelet count, size of spleen and XmnI genotype, however, there was negative correlation between age and hemoglobin level with CBFVs.

A Method to Assess Granger Causality, Isolation and Autonomy in the Time and Frequency Domains: Theory and Application to Cerebrovascular Variability.

Concepts of Granger causality (GC) and Granger autonomy (GA) are central to assess the dynamics of coupled physiologic processes. While causality measures have been already proposed and largely applied in time and frequency domains, measures quantifying self-dependencies are still limited to the time-domain formulation and lack of a clear spectral representation. We embed into the classical linear parametric framework for computing GC from a driver random process X to a target process Y a measure of Granger Isolation (GI) quantifying the part of the dynamics of Y not originating from X, and a new spectral measure of GA assessing frequency-specific patterns of self-dependencies in Y. The framework is formulated in a way such that the full-frequency integration of the spectral GC, GI and GA measures returns the corresponding time-domain measures. The measures are illustrated in theoretical simulations and applied to time series of mean arterial pressure and cerebral blood flow velocity obtained in subjects prone to develop postural syncope and healthy controls. simulations show that GI is complementary to GC but not trivially related to it, while GA reflects the regularity of the internal dynamics of the analyzed target process. In the application to cerebrovascular interactions, spectral GA quantified the physiological response to postural stress of slow cerebral blood flow oscillations, while spectral GC and GI detected an altered response to postural stress in subjects prone to syncope, likely related to impaired cerebral autoregulation. The new spectral measures of GI and GA are useful complements to GC for the analysis of interacting oscillatory processes, and detect physiological and pathological responses to postural stress which cannot be traced in the time domain. The thorough assessment of causality, isolation and autonomy opens new perspectives for the analysis of coupled biological processes in both physiological and clinical investigations.

Clinical study of acupuncture combined with medication for the elderly with Alzheimer disease

ObjectiveTo observe the impact of mind-regulating acupuncture plus donepezil on the cognitive ability, mean cerebral blood flow velocity, event-related potential P300, and activities of daily living (ADL) in the aged patients with Alzheimer disease (AD).MethodsSixty senile AD patients were divided into a treatment group and a control group following the envelope method for random allocation, with 30 cases in each group. Based on the conventional treatment of the internal medicine, the control group received oral donepezil, and the treatment group received oral donepezil plus mind-regulating acupuncture. After 4-week treatment, the two groups were evaluated by the mini-mental state examination (MMSE), Alzheimer disease assessment scale-cognitive part (ADAS-Cog), and ADL; changes in P300 and the mean cerebral blood flow velocity were also observed.ResultsBefore treatment, there were no significant differences in the scores of MMSE, ADAS-Cog, or ADL between the two groups (P>0.05). The MMSE score increased after treatment in both groups and was notably higher in the treatment group than in the control group, showing intra-group and inter-group statistical significance (P<0.05). After treatment, the ADAS-Cog and ADL scores dropped in both groups and were markedly lower in the treatment group than in the control group, also showing intra-group and inter-group statistical significance (P<0.05). Compared with the same group before treatment, the latency of P300 was shortened and the amplitude was extended in both groups, all with statistical significance (P<0.05); the latency was shorter and the amplitude was larger in the treatment group than in the control group after treatment, presenting significant between-group differences (P<0.05). The mean blood flow velocity accelerated after the intervention in both groups, and the differences were statistically significant (P<0.05); the improvement in the treatment group was more notable than that in the control group (P<0.05).ConclusionMind-regulating acupuncture plus donepezil can regulate the latency and amplitude of P300, increase cerebral blood flow, and improve the learning and memory abilities of AD patients.

Efficacy of median nerve electrical stimulation on the recovery of patients with consciousness disorders: a systematic review and meta-analysis.

To identify whether median nerve stimulation (MNS) may be a potential candidate for the treatment of consciousness disorders via a systematic review and meta-analysis. PubMed, Cochrane Library, China National Knowledge Infrastructure, Chinese VIP Information, Wanfang, and SinoMed databases were searched. Risk of bias was assessed using the Cochrane Collaboration's tool. The Glasgow Coma Scale (GCS), Disability Rating Scale (DRS), electroencephalogram (EEG), days in the Intensive Care Unit (ICU), and cerebral blood flow measures were compared between the median nerve stimulation and control groups. The meta-analysis was conducted using Review Manager software. We identified 2244 studies, of which 23 (with data from 1856 patients) qualified for the analysis. MNS improved GCS scores (mean difference [MD] = 2.15), EEG scores (MD = 1.61), cerebral mean blood flow velocity (MD = 4.23), and cerebral systolic blood flow velocity (MD = 10.51). Furthermore, it decreased DRS scores (MD = -1.77) and days in the ICU (MD = -2.02). The effects of MNS on GCS scores increased with longer treatments (1 week, MD = 1.03; 1 month, MD = 2.35) and were better with right MNS (right, MD = 2.36; bilateral, MD = 1.72). MNS may promote recovery from consciousness disorders.

Dynamic effects of cholinergic blockade upon cerebral blood flow autoregulation in healthy adults.

Background: Cerebral flow autoregulation (CFA) is a homeostatic mechanism critical for survival. The autonomic nervous system (ANS) plays a key role in maintaining proper CFA function. More quantitative studies of how the ANS influences CFA are desirable. Objective: To discover and quantify the dynamic effects of cholinergic blockade upon CFA in response to changes of arterial blood pressure and blood CO2 tension in healthy adults. Methods: We analyzed time-series data of spontaneous beat-to-beat mean arterial blood pressure (ABP) and cerebral blood flow velocity in the middle cerebral arteries (CFV), as well as breath-to-breath end-tidal CO2 (CO2), collected in 9 adults before and after cholinergic blockade, in order to obtain subject-specific predictive input-output models of the dynamic effects of changes in ABP and CO2 (inputs) upon CFV (output). These models are defined in convolutional form using "kernel" functions (or, equivalently, Transfer Functions in the frequency domain) that are estimated via the robust method of Laguerre expansions. Results: Cholinergic blockade caused statistically significant changes in the obtained kernel estimates (and the corresponding Transfer Functions) that define the linear dynamics of the ABP-to-CFV and CO2-to-CFV causal relations. The kernel changes due to cholinergic blockade reflect the effects of the cholinergic mechanism and exhibited, in the frequency domain, resonant peaks at 0.22 Hz and 0.06Hz for the ABP-to-CFV and CO2-to-CFV dynamics, respectively. Conclusion: Quantitative estimates of the dynamics of the cholinergic component in CFA are found as average changes of the ABP-to-CFV and CO2-to-CFV kernels, and corresponding Transfer Functions, before and after cholinergic blockade.

Exploring metrics for the characterization of the cerebral autoregulation during head-up tilt and propofol general anesthesia.

Techniques grounded on the simultaneous utilization of Tiecks' second order differential equations and spontaneous variability of mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV), recorded from middle cerebral arteries through a transcranial Doppler device, provide a characterization of cerebral autoregulation (CA) via the autoregulation index (ARI). These methods exploit two metrics for comparing the measured MCBFV series with the version predicted by Tiecks' model: normalized mean square prediction error (NMSPE) and normalized correlation ρ. The aim of this study is to assess the two metrics for ARI computation in 13 healthy subjects (age: 27±8yrs., 5 males) at rest in supine position (REST) and during 60° head-up tilt (HUT) and in 19 patients (age: 64±8yrs., all males), scheduled for coronary artery bypass grafting, before (PRE) and after (POST) propofol general anesthesia induction. Analyses were carried out over the original MAP and MCBFV pairs and surrogate unmatched couples built individually via time-shifting procedure. We found that: i) NMSPE and ρ metrics exhibited similar performances in passing individual surrogate test; ii) the two metrics could lead to different ARI estimates; iii) CA was not different during HUT or POST compared to baseline and this conclusion held regardless of the technique and metric for ARI estimation. Results suggest a limited impact of the sympathetic control on CA.

Spectral decomposition of cerebrovascular and cardiovascular interactions in patients prone to postural syncope and healthy controls

We present a framework for the linear parametric analysis of pairwise interactions in bivariate time series in the time and frequency domains, which allows the evaluation of total, causal and instantaneous interactions and connects time- and frequency-domain measures. The framework is applied to physiological time series to investigate the cerebrovascular regulation from the variability of mean cerebral blood flow velocity (CBFV) and mean arterial pressure (MAP), and the cardiovascular regulation from the variability of heart period (HP) and systolic arterial pressure (SAP). We analyze time series acquired at rest and during the early and late phase of head-up tilt in subjects developing orthostatic syncope in response to prolonged postural stress, and in healthy controls. The spectral measures of total, causal and instantaneous coupling between HP and SAP, and between MAP and CBFV, are averaged in the low-frequency band of the spectrum to focus on specific rhythms, and over all frequencies to get time-domain measures. The analysis of cardiovascular interactions indicates that postural stress induces baroreflex involvement, and its prolongation induces baroreflex dysregulation in syncope subjects. The analysis of cerebrovascular interactions indicates that the postural stress enhances the total coupling between MAP and CBFV, and challenges cerebral autoregulation in syncope subjects, while the strong sympathetic activation elicited by prolonged postural stress in healthy controls may determine an increased coupling from CBFV to MAP during late tilt. These results document that the combination of time-domain and spectral measures allows us to obtain an integrated view of cardiovascular and cerebrovascular regulation in healthy and diseased subjects.

Effect of Kangaroo Mother Care on Cerebral Hemodynamics in Preterm Neonates Assessed by Transcranial Doppler Sonography in Middle Cerebral Artery

To study the effect of KMC in premature newborns on cerebral hemodynamics in the middle cerebral artery (MCA) using transcranial doppler sonography. In this descriptive study, 40 clinically stable preterm neonates admitted to the neonatal intensive care unit of our institute and undergoing Kangaroo mother care (KMC) were enrolled. Physiological and cerebral blood flow parameters of MCA were obtained by using transcranial doppler sonography at baseline, at 60 minutes of KMC, and after 60 minutes of stopping KMC. Of the 40 enrolled neonates (24 males), the mean (SD) birth weight, gestation age, and postnatal age were 1698.25 (495.44) g, 33.00 (1.67) wk, and 6.80 (4.51) days, respectively. The mean (SD) cerebral blood flow velocities increased (peak systolic velocity (PSV), P=0.03; end diastolic velocity, P<0.001; mean velocity, P<0.001) and doppler indices decreased (resis-tive index, P=0.001; pulsatility index, P<0.001) significantly; whereas, heart rate (P<0.001) decreased but SpO2 (P=0.001) and mean blood pressure (P=0.003) increased significantly at 60 minutes of KMC as compared to baseline. Sixty minutes after stopping KMC, all parameters (except PSV) were higher than baseline, indicating post KMC effect. KMC improves cerebral hemodynamics in clinically stable preterm neonates.

Aerobic exercise training reduces cerebrovascular impedance in older adults: a 1-year randomized controlled trial.

Older adults have higher cerebrovascular impedance than young individuals which may contribute to chronic brain hypoperfusion. Besides, middle-aged athletes exhibit lower cerebrovascular impedance than their sedentary peers. We examined whether aerobic exercise training (AET) reduces cerebrovascular impedance in sedentary older adults. We conducted a proof-of-concept trial that randomized 73 older adults to 1 yr of AET (n = 36) or stretching and toning (SAT, n = 37) interventions. Cerebrovascular impedance was estimated from simultaneous recordings of carotid artery pressure (CAP) via applanation tonometry and cerebral blood flow velocity (CBFV) in the middle cerebral artery via transcranial Doppler using transfer function analysis. Fifty-six participants completed 1-yr interventions, and 41 of those completed cerebrovascular impedance measurements. AET group showed a significant increase in V̇o2peak after the intervention [estimated marginal mean (95% confidence interval); from 22.8 (21.6 to 24.1) to 24.9 (23.6 to 26.2) mL·kg-1·cm-1, P < 0.001], but not SAT [from 21.7 (20.5 to 22.9) to 22.3 (21.1 to 23.7) mL·kg-1·cm-1, P = 0.114]. Coherence between changes in CBFV and CAP was >0.90 in the frequency range of 0.78-3.12 Hz. The averaged cerebrovascular impedance modulus (Z) in this frequency range decreased after 1-yr AET [from 1.05 (0.96 to 1.14) to 0.95 (0.92 to 1.06) mmHg·s·cm-1, P = 0.023], but not SAT [from 0.96 (0.87 to 1.04) to 1.01 (0.92 to 1.10) mmHg·s·cm-1, P = 0.138]. Reductions in Z were correlated positively with reductions in carotid pulse pressure (r = 0.628, P = 0.004) and inversely with mean CBFV (r = -0.563, P = 0.012) in the AET group. One-year AET reduces cerebrovascular impedance in older adults, which may benefit brain perfusion.NEW & NOTEWORTHY Estimation of cerebrovascular impedance is essential for understanding dynamic cerebral blood flow regulation. This randomized controlled trial demonstrated that aerobic exercise training reduced cerebrovascular impedance in older adults, which may benefit brain perfusion.