What drives transcranial Doppler velocity improvement in paediatric sickle cell anaemia: analysis from the Sickle Cell Clinical Research and Intervention Program (SCCRIP) longitudinal cohort study.

Children with sickle cell anaemia (SCA) and conditional transcranial Doppler (TCD) flow velocities (conditional: 170-199 cm/s; normal: <170 cm/s) have an increased risk of stroke. The Sickle Cell Clinical Research and Intervention Program (SCCRIP), a lifetime observational study, assessed the influence of haematological markers on TCD velocities. In children (≤16 years) with SCA (HbSS/HbSß0 -thalassaemia) and conditional TCD velocities (n = 32), increases in haemoglobin and in fetal haemoglobin after hydroxyurea initiation were significantly associated with decreases in TCD velocities. The benefit of pharmacological intervention to increase haemoglobin and fetal haemoglobin and normalise TCD velocities was demonstrated in this real-world dataset.

Cerebral monitoring during transcarotid artery revascularization with flow reversal via transcranial doppler ultrasound examination.

OBJECTIVE: Transcarotid artery revascularization (TCAR) is a hybrid technique for carotid artery revascularization that relies on proximal carotid occlusion with flow reversal for distal embolic protection. The hemodynamic response of the intracranial circulation to flow reversal is unknown. In addition, the rate and pattern of cerebral embolization during flow reversal has yet to be investigated. The aim of this study was to characterize cerebral hemodynamic and embolization patterns during TCAR. METHODS: A single-institution retrospective study of patients with carotid artery stenosis undergoing TCAR with intraoperative transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA) was performed. Primary outcomes included changes in MCA velocity and MCA embolic signals observed throughout TCAR. RESULTS: Eleven patients underwent TCAR with TCD monitoring of the ipsilateral MCA. The average MCA velocity at baseline was 50.6 ± 16.4 cm/s. MCA flow decreased significantly upon initiation of flow reversal (50.5 ± 16.4 cm/s vs 19.1 ± 18.4 cm/s; P = .02). The reinitiation of antegrade flow resulted in a significant increase in the number of embolic events compared with baseline (P = .003), and embolic events were observed in two patients during flow reversal. CONCLUSIONS: TCD monitoring of patients undergoing TCAR revealed that the initiation of flow reversal results in a decrement in ipsilateral MCA velocity. Furthermore, embolic events can occur during flow reversal and are significantly associated with the reinitiation of antegrade flow in the internal carotid artery. However, both of these hemodynamic events were well-tolerated in our cohort. These findings suggest that TCAR remains a safe neuroprotective strategy for carotid revascularization.

Transcranial Doppler Velocities among Sickle Cell Disease Patients in Steady State.

Transcranial Doppler (TCD) screening is an established tool to identify children with sickle cell disease at high risk of stroke. Our objective was to study TCD velocities among sickle cell disease patients while in a steady state. This cross-sectional study included 78 steady state sickle cell disease patients [31 Hb SS (ßS/ßS) (sickle cell anemia), 47 Hb S/ß-thalassemia (HBB: c.20A>T/ß-thal)], attending the Pediatric Hematology Clinic at Cairo University Children's Hospital, Cairo, Egypt. All patients underwent TCD velocity assessment as per the Stroke Prevention Trial in Sickle Cell Anemia (STOP) protocol. In our cohort, TCD velocities were comparable among Hb S/ß-thal vs. SS patients. Hemolysis indicators correlated significantly to TCD velocities in Hb S/ß-thal patients; positive correlation was found between total bilirubin level and right middle cerebral artery (MCA) and right distal internal carotid artery (dICA) TCD velocities (r = 0.428, p = 0.00, r = 0.360, p = 0.01), respectively as well as between reticulocyte count and right MCA, right dICA and right anterior cerebral artery (ACA) TCD velocities (r = 0.424, p = 0.01), (r = 0.40, p = 0.00), (r = 0.303, p = 0.04), respectively. On the other hand, statistically significant negative correlations were found between hemoglobin (Hb) level and right ACA, right dICA TCD velocities (r = -0.290, p = 0.05), (r = -0.324, p = 0.03). Although Hb F is considered an ameliorating factor for disease severity; hemolysis stands as an indicator of risk for TCD velocity elevation, and in turn, risk for stroke among sickle cell disease patients.

Temporal Relationship between Hyponatremia and Development of Cerebral Vasospasm in Aneurysmal Subarachnoid Hemorrhage Patients: A Retrospective Observational Study.

BACKGROUND: Hyponatremia is a common complication after aneurysmal subarachnoid hemorrhage (aSAH). Previous studies have reported an association between hyponatremia and vasospasm, however whether hyponatremia directly contributes to the pathogenesis of cerebral vasospasm (CVS), or is a by-product is still unclear. The aim of this study was to explore an association between hyponatremia and CVS after aSAH, and evaluating the temporality of these 2 events. METHODS: A retrospective study of consecutive patients with aSAH admitted to the Baylor St. Luke's Medical center between January 2008 and December 2012 was conducted. Demographics, baseline characteristics, serum sodium levels, and evidence of vasospasm detected by transcranial Doppler, CT Angiogram, MR angiogram, and digital subtracted angiography were collected. Patients were dichotomized into a hyponatremic and a normonatremic group. CVS incidence and clinical outcome was compared between groups. Timing of CVS after initial hyponatremia episodes was recorded Results: One hundred and sixty 4 patients with aSAH were included. Hyponatremia was identified in 66 patients (40.2%) and CVS occurred in 71 subjects (43.2%). The incidence of CVS was higher in the hyponatremic group compared to the normonatremic group, 65.1 % versus 28.5%, respectively (P < .001). Hyponatremia preceded CVS by median 1.5 days suggesting a temporal trend. CONCLUSIONS: Our study shows a significant association between hyponatremia and CVS, with hyponatremia preceding CVS events. This retrospective finding denotes the need for larger prospective studies, aiming to clarify the temporal relationship of serum sodium levels and CVS.

Serum Levels of S100b and NSE Proteins in Patients with Non-Transfusion-Dependent Thalassemia as Biomarkers of Brain Ischemia and Cerebral Vasculopathy.

Patients with non-transfusion-dependent thalassemia (NTDT) are at risk of developing brain ischemia. Transcranial Doppler (TCD) has been established as a useful screening tool of cerebrovascular disease in patients with sickle cell disease. Proteins neuron specific enolase (NSE) and S100B are biomarkers that reflect CNS injury. The purpose of this study is to evaluate cerebral vessel vasculopathy and brain damage in NTDT patients using non-invasive methods as TCD and measurement serum levels of NSE and S100B. We included in our study 30 patients with NTDT, aged between 8 and 62 years old (mean: 29.4, median: 32) who presented in our Unit for regular follow-up. We performed in all patients a non-imaging TCD examination and have measured serum S100, NSE and lactate dehydrogenase (LDH) levels. We investigated the possible correlation between TCD results and S100B, NSE and LDH levels as well as between NSE-LDH and S100B-LDH levels by regression analysis. We found a statistically significant relationship for both NSE, S100B with LDH. We also found a statistically significant relationship for S100B and time-averaged mean velocity (TAMV)/peak velocity of left middle cerebral artery (MCA), NSE and pulsatility index (PI)/resistive index (RI) of the left posterior cerebral artery (PCA). TCD results correlated with biomarkers for brain ischemia. This finding enhances the role of TCD as a screening tool for brain ischemia in patients with NTDT.

New evidence for fractional pressure ratio prediction by pulsatility index from transcranial Doppler in patients with symptomatic cerebrovascular stenosis disease.

Background: The pulsatility index (PI) derived from transcranial Doppler (TCD) assessment may represent the cerebral resistance and altered cerebral blood flow. The purpose of this study was to assess the performance of the TCD PI in correlation with wire-based fractional pressure ratio (FPR). Methods: This study included 33 patients with symptomatic atherosclerotic lesions of the extracranial and intracranial large arteries, specifically the internal carotid artery, middle cerebral artery (MCA), vertebral artery (VA) V4 segment, and basilar artery (BA), all of which exhibited luminal stenosis ranging from 50% to 70%. TCD was performed prior to angiography in order to determine the flow distal to the lesion. We performed cerebrovascular angiography with a pressure wire to measure the FPR of vessels with stenotic lesions. Bland-Altman analysis and ordinal least square (OLS) linear regression were used to quantify the correlation between PI and FPR. Results: A total of 42 TCD data points were analyzed. At the TCD locations distal to the lesions, the correlation coefficients were no less than 0.90%, with almost all P values <0.001, which indicated very strong positive correlations; the exception to this was the distal TCD for MCA segment lesions (r=0.897; P=0.015) and VA V4 segment (r=0.964; P=0.036). The Bland-Altman plot demonstrated a small difference (0.003) between the distal TCD PI and the FPR, with an acceptable 95% confidence interval [95% confidence interval (CI): 0.06-0.12]. Conclusions: The PI obtained through TCD assessment distal to the stenotic lesion exhibited a correlation with the FPR computed using pressure wire measurements.

Cerebral Pulsatility Index and In-Hospital Mortality in Chinese Patients with Traumatic Brain Injury: A Retrospective Cohort Study.

There are limited studies on the relationship between the vascular transcranial Doppler (TCD) pulsatility index (PI) and in-hospital mortality in patients with traumatic brain injury (TBI). To address this issue, we conducted this study to explore whether, in newly diagnosed Chinese TBI patients, the PI is an independent predictor of the in-hospital mortality rate after adjusting for other covariates. This study is a retrospective cohort study. From 24 March 2019 to 24 January 2020, we recruited 144 Chinese patients with newly diagnosed TBI from a Chinese hospital. The independent variable was the PI, and the dependent variable was in-hospital mortality in TBI patients. The relationship between the PI and in-hospital mortality in TBI patients was nonlinear and had an inflection point of 1.11. In the multivariate analysis, after adjusting for potential confounders, the effect sizes and confidence intervals per additional 0.1 units on the left and right sides of the inflection point were 4.09 (1.30-12.83) and 1.42 (0.93-2.17). The relationship between the PI and in-hospital mortality was nonlinear. The PI was positively related with in-hospital mortality when the PI was less than 1.11.

Retroauricular/Transcranial Color-Coded Doppler Ultrasound Approach in Junction With Ipsilateral Neck Compression on Real-Time Hydroacoustic Variation of Venous Pulsatile Tinnitus.

Alterations in dural venous sinus hemodynamics have recently been suggested as the major contributing factors in venous pulsatile tinnitus (PT). Nevertheless, little is known about the association between real-time alterations in hemodynamics and the subjective perception of venous PT. This study aimed to investigate the hydroacoustic correlations among diverticular vortices, mainstream sinus flow, and PT using various Doppler ultrasound techniques. Nineteen venous PT patients with protrusive diverticulum were recruited. The mainstream sinus and diverticular hemodynamics before and after ipsilateral internal jugular vein (IJV) compression were investigated using an innovative retroauricular color-coded Doppler (RCCD) method to examine the correlation between the disappearance of PT and hemodynamic alterations. To reveal the hydroacoustic characteristics of disparate segments of venous return, a computational fluid dynamics (CFD) technique combined with the transcranial color-coded Doppler method was performed. When the ipsilateral IJV was compressed, PT disappeared, as the mean velocity of mainstream sinus flow and diverticular vortex decreased by 51.2 and 50.6%, respectively. The vortex inside the diverticulum persisted in 18 of 19 subjects. The CFD simulation showed that the flow amplitude generated inside the transverse-sigmoid sinus was segmental, and the largest flow amplitude difference was 20.5 dB. The difference in flow amplitude between the mainstream sinus flow and the diverticular flow was less than 1 dB. In conclusion, the sensation of PT is closely associated with the flow of kinetic energy rather than the formation of a vortex, whereby the amplitude of PT is correlated to the magnitude of the flow velocity and pressure gradient. Additionally, the range of velocity reduction revealed by the RCCD method may serve as a presurgical individual baseline curative marker that may potentially optimize the surgical outcomes.

Validation of a cerebral hemodynamic model with personalized calibration in patients with aneurysmal subarachnoid hemorrhage.

This study aims to validate a numerical model developed for assessing personalized circle of Willis (CoW) hemodynamics under pathological conditions. Based on 66 computed tomography angiography images, investigations were obtained from 43 acute aneurysmal subarachnoid hemorrhage (aSAH) patients from a local neurovascular center. The mean flow velocity of each artery in the CoW measured using transcranial Doppler (TCD) and simulated by the numerical model was obtained for comparison. The intraclass correlation coefficient (ICC) over all cerebral arteries for TCD and the numerical model was 0.88 (N = 561; 95% CI 0.84-0.90). In a subgroup of patients who had developed delayed cerebral ischemia (DCI), the ICC had decreased to 0.72 but remained constant with respect to changes in blood pressure, Fisher grade, and location of ruptured aneurysm. Our numerical model showed good agreement with TCD in assessing the flow velocity in the CoW of patients with aSAH. In conclusion, the proposed model can satisfactorily reproduce the cerebral hemodynamics under aSAH conditions by personalizing the numerical model with TCD measurements. Clinical trial registration: [http://www.trialregister.nl/], identifier [NL8114].

Comparison of Unilateral Middle Cerebral Artery and Bilateral Middle Cerebral Artery Monitoring for Right-to-Left Shunt Detection by Contrast-Enhanced Transcranial Doppler.

Introduction: Contrast-enhanced transcranial Doppler (c-TCD) is a noninvasive test with high sensitivity for the detection of a right-to-left shunt (RLS). Currently, there are no reports on the outcomes of unilateral versus bilateral middle cerebral artery (MCA) monitoring. This study compared the positivity rate of bilateral MCA monitoring with unilateral MCA monitoring for RLS using c-TCD. Methods: We enrolled 239 patients (86 women and 153 men) with a mean age of 48.54 ± 13.25 years (range, 14-79 years), who underwent c-TCD examination in the Department of Transcranial Doppler Ultrasound of our hospital between February 2018 and February 2021, due to suspicion of RLS. Bilateral MCA monitoring of 239 patients was performed using dual-channel and dual-depth c-TCD. The positive rate and shunt classification of RLS were calculated for left, right, and bilateral MCA monitoring. The differences in RLS detected by c-TCD monitoring of the left, right and bilateral MCA were compared. Results: In the left middle cerebral artery (LMCA) monitoring, 35.56% (85 of 239) had a positive RLS result, 38 cases were permanent (44.70%), and 47 cases were latent (55.30%). In the right middle cerebral artery (RMCA) monitoring, 36.82% (88 of 239) had a positive RLS result, 38 cases were permanent (43.18%), and 50 cases were latent (56.82%). In the bilateral MCA group, 43.09% (103 of 239) had a positive RLS result, 50 cases were permanent (48.54%) and 53 were latent (51.46%). The positive rate of bilateral MCA monitoring was higher than that of LMCA and RMCA (43.09, 35.56, and 36.82%, respectively), and the difference was not statistically significant (P = 0.193). The positive rate of bilateral MCA monitoring was higher than that of LMCA and RMCA for mild and moderate shunts, but the difference was not statistically significant. The positive rate of bilateral MCA monitoring was equal to that of RMCA, but higher than that of LMCA, with no statistical significance. LMCA monitoring revealed 85 patients with RLS. The sensitivity was 82.52% (85/103). The specificity was 100%. The RMCA monitoring results showed 88 cases with RLS. The sensitivity was 85.44% (88/103). The specificity was 100%. Conclusions: There was no significant difference in the RLS detection rate between unilateral and bilateral MCA monitoring using c-TCD. Bilateral MCA monitoring may be more advantageous for mild RLS detection.

A systematic review and meta-analysis on transcranial Doppler in diagnosing ischemic cerebrovascular disease.

BACKGROUND: The incidence of ischemic cerebrovascular disease (ICVD) has been increasing, leading to disability and deaths among middle-aged and elderly people. Digital subtraction angiography (DSA) is the gold standard for diagnosing ICVD, but it is invasive, expensive, and complex to operate. Transcranial Doppler (TCD) ultrasound is characterized by high accuracy, simplicity, and low cost, and thus became the focus of this study. METHODS: The databases of PubMed, Web of Science, Embase, and The Cochrane Library were searched from January 2000 to September 2020, for literature involving the use of TCD to diagnose ICVD. The software RevMan 5.3 was used for quality assessment, and forest plots and summary receiver operating characteristic (SROC) curves were drawn. The software STATA12.0 was adopted for publication bias analysis. RESULTS: A total of 11 references were included, and the combined sensitivity, specificity, and 95% confidence interval (CI) of TCD were 0.93 (0.75 to 1.00) and 0.95 (0.78 to 1.00), respectively. The area under the curve (AUC) of SROC was 0.887. DISCUSSION: Superb capabilities in diagnosing ICVD have been demonstrated by TCD, and it should therefore be applied in the clinic. The results are important to realize early diagnosis of ICVD and improve the prognosis of patients.

Non-invasive detection of intracranial pressure related to the optic nerve.

Intracranial pressure (ICP) is associated with a variety of diseases. Early diagnosis and the timely intervention of elevated ICP are effective means to clinically reduce the morbidity and mortality of some diseases. The detection and judgment of reduced ICP are beneficial to glaucoma doctor and neuro ophthalmologist to diagnose optic nerve disease earlier. It is important to evaluate and monitor ICP clinically. Although invasive ICP detection is the gold standard, it can have complications. Most non-invasive ICP tests are related to the optic nerve and surrounding tissues due to their anatomical characteristics. Ultrasound, magnetic resonance imaging, transcranial Doppler, papilledema on optical coherence tomography, visual evoked potential, ophthalmodynamometry, the assessment of spontaneous retinal venous pulsations, and eye-tracking have potential for application. Although none of these methods can completely replace invasive technology; however, its repeatable, low risk, high accuracy, gradually attracted people's attention. This review summarizes the non-invasive ICP detection methods related to the optic nerve and the role of the diagnosis and prognosis of neurological disorders and glaucoma. We discuss the advantages and challenges and predict possible areas of development in the future.

Novel robotic TCD ultrasound with bubbles versus standard care to detect right to left shunt: Study methods.

BACKGROUND AND PURPOSE: Right to left shunt (RLS), from patent foramen ovale (PFO) or elsewhere, is a recognized risk factor for stroke. Current standard of care for RLS diagnosis includes transthoracic echocardiography (TTE) which is insensitive, transesophageal echocardiography (TEE) which is invasive, and transcranial Doppler (TCD) which has excellent sensitivity and specificity for RLS but is heavily operator dependent and expertise is scarce. The purpose of this study was to evaluate the RLS detection rate of a novel robotic-assisted TCD (ra-TCD) to standard of care diagnostic techniques, including TTE, TEE, and TCD. METHODS: This is a multicenter, prospective, single-arm, nonsignificant risk device study of ra-TCD versus TTE for RLS diagnosis in adult patients who present with neurological signs and symptoms that include embolic stroke or transient ischemic attack on the differential diagnosis. Up to 150 subjects will be enrolled at up to seven centers considering the prevalence of PFO, suboptimal transtemporal windows, and potential dropouts. Enrolled patients will undergo ra-TCD supine and at 45° in a manner otherwise in line with standard of care TCD bubble technique. The enrolled patients will have undergone TTE, and optionally standard TCD and TEE, per usual care. RESULTS: The primary efficacy endpoint is percent detection of RLS by ra-TCD compared against TTE. The primary safety endpoint is the incidence of device-related serious adverse events. CONCLUSIONS: This is the first multicenter, prospective study evaluating the accuracy, feasibility, and safety of novel ra-TCD for the diagnosis of RLS as compared to standard of care diagnostics.

Effect of combination invasive intracranial pressure (ICP) monitoring and transcranial Doppler in the treatment of severe craniocerebral injury patients with decompressive craniectomy.

BACKGROUND: The aim of the present study was to explore the clinical effect and to predict the prognosis of severe craniocerebral injury patients with decompressive craniectomy by combining transcranial Doppler (TCD) and invasive intracranial pressure (ICP). METHODS: A total of 60 severe craniocerebral injury patients with decompressive craniectomy, who were admitted to Shantou Central Hospital from June 2017 to March 2019, were enrolled in this retrospective study. Of these, 25 patients who had a Glasgow Coma Scale (GCS) score no greater 8 and no less than 6 underwent transcranial Doppler (TCD) before decompressive craniectomy, as well as ICP, after removing the skull and suturing the dura mater. The 60 patients were divided into 2 groups according to the following standards: (I) GCS score ≥8 on the 7th day postoperatively; (II) ICP continuously lower than 25 mmHg for the entire 7-day duration postoperatively; and (III) brain tissue consistently offset from the skull surface by 5 mm. The clinical outcome was determined based on the Glasgow Outcome Scale (GOS) 1, 3, and 6 months postoperatively. The TCD value, ICP, and prognosis were compared between the 2 groups. RESULTS: The average postoperative ICP <19 mmHg in the first 24 h, mean blood flow velocity >56.33 cm/s, end-diastolic blood flow velocity >40.28 cm/s, and resistance index <0.57 were statistically significant indicators to predict good prognosis . CONCLUSIONS: The use of TCD can predict the prognosis of severe craniocerebral injury patients.

Prevalence and Predictors of Cerebral Microangiopathy Determined by Pulsatility Index in an Asymptomatic Population From the ILERVAS Project.

Background: Little is known about the prevalence of cerebral microangiopathy (CM), which is related to cognitive impairment, in an asymptomatic population. Pulsatility index (PI) is an easily measurable parameter of cerebral vascular resistance in transcranial duplex of the middle cerebral artery (MCA) study. We aimed to determine the prevalence of CM measured by PI of MCA in low to moderate vascular risk subjects. Methods: We included 3,721 subjects between 45 and 70 years without previous history of vascular disease or diabetes mellitus and with at least one other vascular risk factor from the cross-sectional study ILERVAS (Lleida, Spain). Patients underwent transcranial duplex to determine MCA-PI. Possible CM was defined by MCA-PI >1.1. Carotid and femoral arteries ultrasound registration was done to determine the presence, the number, and the area of atheromatous plaques. Body mass index (BMI), pulse pressure (PP) and laboratory data were also recorded. Results: 439 (11.8%) subjects were excluded due to the low quality of transcranial duplex images. Median age was 57 [IQR 52, 62] years. Possible CM was found in 424 (12.9%) subjects. CM patients had higher prevalence of plaques than non-CM (77.4 vs. 66.4%, p < 0.001). PI showed a positive linear correlation with the number of territories with plaques (r = 0.130, p < 0.001), and the total plaque area (r = 0.082, p < 0.001). The predictors of possible CM were the age, male gender, and PP. Conclusions: In low-to-moderate vascular risk asymptomatic population, the proportion of abnormal brain microvascular bed determined by MCA-PI is not negligible. The planned 10-year follow-up will describe the clinical relevance of these findings.

Neurovascular Coupling Is Impaired in Hypertensive and Diabetic Subjects Without Symptomatic Cerebrovascular Disease.

The mechanistic link between hypertension, diabetes and cerebral small vessel disease (CSVD) is still poorly understood. We hypothesized that hypertension and diabetes could impair cerebrovascular regulation prior to irreversibly established cerebrovascular disease. In this study, 52 hypertensive patients [54% males; age 64 ± 11 years; 58% with comorbid diabetes mellitus (DM)] without symptomatic cerebrovascular disease underwent transcranial Doppler (TCD) monitoring in the middle (MCA) and posterior (PCA) cerebral arteries, to assess vasoreactivity to carbon dioxide (VRCO2) and neurovascular coupling (NVC). 1.5T magnetic resonance imaging was also performed and white matter hyperintensity volume was automatically segmented from FLAIR sequences. TCD data from 17 healthy controls were obtained for comparison (47% males; age 60 ± 16 years). Hypertensive patients showed significant impairment of NVC in the PCA, with reduced increment in cerebral blood flow velocity during visual stimulation (22.4 ± 9.2 vs. 31.6 ± 5.7, p < 0.001), as well as disturbed NVC time-varying properties, with slower response (lower rate time: 0.00 ± 0.02 vs. 0.03 ± 6.81, p = 0.001), and reduced system oscillation (reduced natural frequency: 0.18 ± 0.08 vs. 0.22 ± 0.06, p < 0.001), when compared to controls. VRCO2 remained relatively preserved in MCA and PCA. These results were worse in hypertensive diabetic patients, with lower natural frequency (p = 0.043) than non-diabetic patients. White matter disease burden did not predict worse NVC. These findings suggest that hypertensive diabetic patients may have a precocious impairment of NVC, already occurring without symptomatic CSVD. Future research is warranted to evaluate whether NVC assessment could be useful as an early, non-invasive, surrogate marker for CSVD.

Impaired Dynamic Cerebral Autoregulation in Cerebral Venous Thrombosis.

Background: Cerebral autoregulation is crucial in traumatic brain injury, which might be used for determining the optimal intracranial pressure. Cerebral venous thrombosis (CVT) is a cerebral vascular disease with features of high intracranial pressure. However, the autoregulatory mechanism of CVT remains unknown. We aimed to investigate the capacity of cerebral autoregulation in patients with CVT. Methods: This study consecutively enrolled 23 patients with CVT and 16 controls from December 2018 to May 2019. Cerebral autoregulation was assessed by transfer function analysis (rate of recovery/phase/gain) using the spontaneous oscillations of the cerebral blood flow velocity and arterial blood pressure. Results: In total, 76 middle cerebral arteries (MCAs) were investigated, including 44 MCAs in patients with CVT and 32 normal ones. The phase shift estimated in patients with CVT was significantly different from that of the controls (37.37 ± 36.53 vs. 54.00 ± 26.78, p = 0.03). The rate of recovery and gain in patients with CVT were lower than those in controls but without statistical significance. Conclusion: To our knowledge, this is the first time that a study has indicated that patients with CVT were more likely to have impaired cerebral autoregulation. Hence, cautious blood pressure control is required in such patients to prevent hyper- or hypoperfusion.

Uses of ultrasound in stroke prevention.

Ultrasound methods are useful in stroke prevention in several ways. Measurement of carotid plaque burden, as either total plaque area (TPA) or total plaque volume (TPV) are strong predictors of cardiovascular risk: much stronger than intima-media thickness, which does not represent true atherosclerosis, but a biologically and genetically distinct phenotype. Measurement of plaque burden is also useful for the study of genetics, and of new risk factors such as toxic products of the intestinal microbiome. Carotid plaque burden is highly correlated with and as predictive of risk as coronary calcium scores, but is less costly and does not require radiation. Furthermore, because carotid plaques change in time over a period of months, they can be used for a new approach to vascular prevention: "Treating arteries instead of treating risk factors". In high-risk patients with asymptomatic carotid stenosis (ACS), this approach, implemented in 2003 in our clinics, was associated with a >80% reduction of stroke and myocardial infarction over 2 years. "Treating arteries without measuring plaque would be like treating hypertension without measuring blood pressure". Ultrasound methods can also be used to assess plaque vulnerability, by detecting echolucency, ulceration and plaque inhomogeneity on assessment of plaque texture. Transcranial Doppler (TCD) embolus detection is useful for risk stratification in patients with ACS; patients with two or more microemboli in an hour of monitoring have a 1-year risk of 15.6%, vs. 1% without microemboli, so this very clearly distinguishes which patients with ACS could benefit from intervention. TCD saline studies are more sensitive than trans-esophageal echocardiography for detection of patent foramen ovale, and more predictive of recurrent stroke. These methods should be more widely used, to reduce the increasing burden of stroke in our aging populations.

Powered Air Purifying Respirator (PAPR) restores the N95 face mask induced cerebral hemodynamic alterations among Healthcare Workers during COVID-19 Outbreak.

BACKGROUND AND AIM: COVID-19 pandemic has resulted in an unprecedented increased usage of Personal protective equipment (PPE) by healthcare-workers. PPE usage causes headache in majority of users. We evaluated changes in cerebral hemodynamics among healthcare-workers using PPE. METHODS: Frontline healthcare-workers donning PPE at our tertiary center were included. Demographics, co-morbidities and blood-pressure were recorded. Transcranial Doppler (TCD) monitoring of middle cerebral artery was performed with 2-MHz probe. Mean flow velocity (MFV) and pulsatility index (PI) were recorded at baseline, after donning N95 respirator-mask, and after donning powered air-purifying respirator (PAPR), when indicated. End-tidal carbon-dioxide (ET-CO2) pressure was recorded for participants donning PAPR in addition to the N95 respirator-mask. RESULTS: A total of 154 healthcare-workers (mean age 29 ± 12 years, 67% women) were included. Migraine was the commonest co-morbidity in 38 (25%) individuals while 123 (80%) developed de-novo headache due to N95 mask. Donning of N95 respirator-mask resulted in significant increase in MFV (4.4 ± 10.4 cm/s, p < 0.001) and decrease in PI (0.13 ± 0.12; p < 0.001) while ET-CO2 increased by 3.1 ± 1.2 mmHg (p < 0.001). TCD monitoring in 24 (16%) participants donning PAPR and N95 respirator mask together showed normalization of PI, accompanied by normalization of ET-CO2 values within 5-min. Combined use of N95 respirator-mask and PAPR was more comfortable as compared to N95 respirator-mask alone. CONCLUSION: Use of N95 respirator-mask results in significant alterations in cerebral hemodynamics. However, these effects are mitigated by the use of additional PAPR. We recommend the use of PAPR together with the N95 mask for healthcare-workers doing longer duties in the hospital wards.

An Educational Study Promoting the Delivery of Transcranial Doppler Ultrasound Screening in Paediatric Sickle Cell Disease: A European Multi-Centre Perspective.

BACKGROUND: Effective stroke prevention in sickle cell disease (SCD) is recommended for children with sickle cell anaemia. Effective implementation relies on the correct stratification of stroke risk using Transcranial Doppler Ultrasound (TCD), prior to committing children to long-term treatment with transfusion. Nevertheless, less than 50% of children with SCD in Europe receive annual TCD-one of the reasons being a lack of trained personnel. The present European multi-centre study was designed to promote the standardisation and delivery of effective screening. METHODS: Fifty-five practitioners from differing professional backgrounds were recruited to the TCD training program. The impact of the training programme was evaluated in three European haematology clinics by comparing stroke risk classification and middle cerebral artery time-averaged maximum velocity (TAMMV) obtained from a cohort of 555 patients, before and after training. RESULTS: 42% (23/55) of trainees successfully completed the program. The TAMMV, used to predict stroke risk at each Centre, demonstrated the highest values in Centre 3 (p < 0.0001) before training. The imaging-TCD TAMMV was also higher in Centre 3 (p < 0.001). Following training, the TAMMV showed closer agreement between centres for both imaging-TCD and non-imaging TCD. The stroke risk distribution of children at each centre varied significantly before training (p < 0.001), but improved after training (Fisher's Exact: no treatment = 5.6, p = 0.41, treatment = 13.8, p < 0.01). The same consistency in stroke risk distribution following training was demonstrated with both non-imaging and imaging-TCD data. CONCLUSION: The attainment of competency in stroke screening using transcranial Doppler scanning (TCD) in sickle cell disease is more feasible for professionals with an ultrasound imaging background. A quality assurance (QA) system is required to ensure that standards are maintained. Further work is in progress to develop an achievable and reproducible QA program.