Transcranial Doppler Ultrasound Examination Research Articles

Intracranial Pressure and Cerebral Hemodynamics in Infants Before and After Glenn Procedure.

This prospective cohort study aimed to investigate changes in intracranial pressure (ICP) and cerebral hemodynamics in infants with congenital heart disease undergoing the Glenn procedure, focusing on the relationship between superior vena cava pressure and estimated ICP. A single-center prospective cohort study. The study was conducted in a cardiac center over 4 years (2019-2022). Twenty-seven infants with congenital heart disease scheduled for the Glenn procedure were included in the study, and detailed patient demographics and primary diagnoses were recorded. Transcranial Doppler (TCD) ultrasound examinations were performed at three time points: baseline (preoperatively), postoperative while ventilated (within 24-48 hr), and at discharge. TCD parameters, blood pressure, and pulmonary artery pressure were measured. TCD parameters included systolic flow velocity, diastolic flow velocity (dFV), mean flow velocity (mFV), pulsatility index (PI), and resistance index. Estimated ICP and cerebral perfusion pressure (CPP) were calculated using established formulas. There was a significant postoperative increase in estimated ICP from 11 mm Hg (interquartile range [IQR], 10-16 mm Hg) to 15 mm Hg (IQR, 12-21 mm Hg) postoperatively (p = 0.002) with a trend toward higher CPP from 22 mm Hg (IQR, 14-30 mm Hg) to 28 mm Hg (IQR, 22-38 mm Hg) postoperatively (p = 0.1). TCD indices reflected alterations in cerebral hemodynamics, including decreased dFV and mFV and increased PI. Intracranial hemodynamics while on positive airway pressure and after extubation were similar. Glenn procedure substantially increases estimated ICP while showing a trend toward higher CPP. These findings underscore the intricate interaction between venous pressure and cerebral hemodynamics in infants undergoing the Glenn procedure. They also highlight the remarkable complexity of cerebrovascular autoregulation in maintaining stable brain perfusion under these circumstances.

The Role of Transcranial Grayscale and Doppler Ultrasound Examination in Diagnosis of Neonatal Hypoxic-Ischemic Encephalopathy

Objectives To evaluate role of transcranial grayscale ultrasound (TC-GSUS) and transcranial color Doppler (TCD) in diagnosis of neonatal Hypoxic-ischemic encephalopathy (HIE). Materials & Methods 26 neonates with suspected HIE underwent sonographic examinations using SonoScape SSI-6000 ultrasound device that is equipped by L743 linear array probe with frequency 5-10 MHz. TC-GSUS was performed at levels of anterior, mastoid and posterior fontanelles and at level of temporal window. TCD was performed using Color-coded Doppler study of the intracerebral vessels to assess brain perfusion and detect ischemic brain changes. Resistance index (RI) was considered abnormal in preterm neonates if it was <0.54 or > 0.86 and if it was <0.52 or > 0.8 for term neonates. Results According to cranial biometry, TC-GSUS has negative and positive rates for HIE of 7.7% and 92.3%, respectively. Using TC-GSUS periventricular leukomalacia, intraventricular hemorrhage, brain edema and hydrocephalus were detected in 17, 19, 14 and 16 patients, respectively. According to RI of intracranial vessels, TCD excluded HIE in 11 patients and assured diagnosis of HIE in 15 patients. TC-GSUS can diagnose HIE in neonates with sensitivity, specificity and accuracy rates of 87.5%, 30% and 65.4%, respectively. ROC curve analysis defined abnormally high RI of intracranial arteries as the significant specific predictor for the presence of NHIE and as the significant sensitive predictor for HIE severity grade. Regression analysis defined high RI of internal carotid artery (ICA) as the most specific predictor for presence of HIE, while high RI of anterior cerebral artery (ACA) was the most sensitive predictor for high grade HIE. Conclusion TCD can diagnose HIE in neonates with high sensitivity and specificity and abnormal RI of ICA and ACA could be used as accurate diagnostic tests. Whenever, TCD was unavailable, TC-GSUS could diagnose HIE with accuracy rate of 65.4% versus TCD.

Bow Hunter's syndrome with clicking sounds: A rare etiology of transient loss of consciousness with tonic-clonic seizure.

We present the case of a young male patient experiencing a transient loss of consciousness and manifesting a seizure when he tilted his head backward. Transcranial Doppler ultrasound (TCD) and carotid artery ultrasound (CAU) examination were normal when the patient's neck was in the neutral position. However, the CAU revealed vertebral artery (VA) transient occlusion during neck rotation or backward movement. Electroencephalogram (EEG) monitoring was performed with multiple neck rotation-induced tests. The patient developed dizziness, which was the same as the prodromal symptoms of the first seizure, and the EEG showed a large number of spinal slow waves and sharp slow waves in the frontal-to-frontal midline area, with an occasional generalization trend. CT angiography revealed occipitalization of the atlas and the lack of contrast agent filling in the local area of the VA when the patient's head was turned contralaterally. Thus, the patient was diagnosed with Bow Hunter's syndrome (BHS) and treated conservatively with neck immobilization. No recurrence occurred at 3 and 6 months of follow-up. Therefore, this case alerts neurologists to suspect BHS on observing seizure manifestations during neck rotation, and CAU may be a recommended dynamic screening method for BHS. This report is accompanied by a discussion of the phenomenon and diagnosis in the context of the existing literature.

Implementation of Transcranial Doppler Ultrasound Stroke Risk Screening in Urban and Rural Sickle Cell Disease Clinics in Zambia

Introduction Transcranial Doppler Ultrasound (TCD) has a long-established role in the diagnosis of sickle cell disease (SCD) related vasculopathy, paving the way for therapeutic interventions that reduce stroke risk by 92% in high-risk children. In sub-Saharan Africa (SSA), where 75% of the global burden of SCD resides and an estimated 1.03 million children are afflicted, SCD-associated stroke risk evaluation with TCD remains an urgent unmet need. Methods Through a collaborative network with Nationwide Children's Hospital in the USA, 6 health facilities including two in Zambia, had personnel and infrastructure set up to introduce Transcranial Doppler Ultrasonography clinical and research centres of excellence (TCD-COE). The SSA TCD Academy course, designed to advance the technical expertise and capability of participants to perform TCD was created. Learners completed virtually delivered didactic lectures focused on neuroanatomy, scan techniques, doppler waveform characteristics, diagnostic criteria, and clinical application in children. Thereafter, they underwent a week-long, hands-on, practical, introduction to TCD, to increase understanding of the key concepts and to develop basic TCD scanning proficiency. An electronic registry, collecting demographic, clinical and laboratory data was also set up. Ongoing mentorship occurred through real-time consultation and evaluation with feedback given directly from a TCD expert to trainees as they performed the screening. Following completion of the course, participants trained began TCD screening in existing sickle cell out-patient clinics at their institutions, namely, the University Teaching Hospitals-Children's Hospital in Lusaka, and at Chipata Central Hospital in Chipata, in Zambia. Results Trainees selected included a pediatric neurologist, a pediatrician in training, 2 nurses and 2 radiographers. They completed the TCD academy course content over 6 months’ time. To date, over a period of an additional six months, 171 children in Lusaka and 71 children in Chipata with SCD have undergone their first ever, successful TCD stroke risk screening, using a standardized protocol focused on terminal internal carotid artery and middle cerebral artery evaluation. Plans to incorporate TCD screening into routine clinical care are underway. This will require rolling out the screening from the current outpatient clinic day to additional days, to the in-lay ward, as well as to train more staff. Several factors may have facilitated the successful implementation of TCD services into the SCD clinics. The participating institutions had already established SCD clinics, with dedicated staff, therapeutic interventions, and monitoring facilities in place. A referral system was in place to allow the trained staff to interact with the physicians in charge of each SCD clinic. Additionally, the trainees had prior experience with other kinds of ultrasound performance, allowing for more rapid acquisition of the technical skill. Lastly, TCD screening for stroke risk was considered standard of care, according to the Zambian guidelines, catalyzing a notable pre-existing high awareness among the staff and affected families and a high acceptance of the service. Several challenges were also encountered. The physical space available is relatively limited, with insufficient room to set up TCD equipment and examination tables for children to rest comfortably during examinations. Additional space was provided, and the teams were able to expand to locations adjacent to clinics to overcome this obstacle. Staff often had multiples tasks, oftentimes only a single provider could be present to perform TCD examinations. Providing dedicated time and staff may offset this setback. Additionally, other days when staff were available, screening was limited based on the availability of the single machine. This obstacle was overcome with the provision of an additional TCD unit. Lastly, some families did not have financial means to return for the recommended follow up visits. Conclusions TCD screening, to determine stroke risk in children with SCD in SSA is feasible with a modest degree of investment in equipment, staff, and training.

Transcranial Doppler Ultrasound for Monitoring the Cerebral Hemodynamic Changes and Prognosticating Outcomes in Venoarterial Extracorporeal Membrane-Oxygenated Patients.

Objective Patients receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO) support may have cerebral hemodynamic changes whose impact on patient outcome are not fully elucidated. This study aims to evaluate the correlation between cerebral hemodynamic changes and prognostic outcome in patients during VA-ECMO. Methods Transcranial Doppler (TCD) ultrasound examination was performed to attain the systolic velocity (Vs), diastolic velocity (Vd), mean velocity (Vm), and pulsatility index (PI) of patients undergoing VA-ECMO. Cardiac ultrasound was also performed to assess the correlation between the left ventricular outflow tract velocity time integral (LVOT VTI), left ventricular ejection fraction (LVEF), and middle cerebral artery (MCA) with the systolic peak. Moreover, we assessed the predictive value of LVOT VTI and LVEF in patients with the systolic peak. Patients were divided into survival and death groups according to the 28-day survival period. Clinical data were compared between the two groups to investigate the effects of cerebral hemodynamic changes on the prognosis of VA-ECMO patients. Results We found that the patient's LVOT VTI and LVEF had high predictive values for the systolic peak of the right middle cerebral artery. The initial LVEF, Vs, Vd and PI, and lactate level as well as the MODS incidence rate difference were significantly different between the survival and death groups. In addition, the results showed that the initial Vs value was an independent risk factor for the prognosis of patients undergoing VA-ECMO. Conclusions Cerebral hemodynamic changes may occur in patients supported by VA-ECMO. In addition, a poor cerebral arterial pulsatile blood flow was closely correlated with an unfavorable outcome in these patients.

Small Demyelination of the Cortex May Be a Potential Marker for the Right-to-Left Shunt of the Heart.

Migraine is a common clinical primary headache with unclear aetiology. In recent years, studies have shown that migraine is related to right-to-left shunts (RLS), and some patients with migraine have white matter lesions. However, the relationship among the three is unclear. To explore the characteristics of white matter lesions (WMLs) in migraine patients with right-to-left shunts and to predict the presence of right-to-left shunts through magnetic resonance imaging (MRI) characteristics in patients with migraine, we conducted a retrospective study. We enrolled 214 patients who were diagnosed with migraines in an outpatient clinic from January 2019 to December 2021. All of them had completed contrast transcranial Doppler ultrasound (cTCD) and magnetic resonance imaging (MRI) examination. Through the inclusion and exclusion criteria, 201 patients were finally included. The patients were grouped according to the presence of WMLs and were compared by age, sex, hypertension, diabetes, RLS, and other characteristic data. We observed the MRI fluid attenuation inversion recovery sequence (FLAIR) image and compared the differences in WMLs between the RLS-positive group and the RLS-negative group. There were 71 cases and 130 cases of migraine with and without WMLs, respectively. A statistically significant difference in near-cortical WMLs with RLS in migraine patients was observed (p = 0.007). Logistic regression analysis was adjusted by age, sex, duration of migraine, and severity. Migraine with aura and family history identified the RLS status as the sole determinant for the presence of near-cortical WMLs (OR = 2.69; 95%CI 1.386–5.219; p = 0.003). Near-cortical white matter lesions in migraine patients are related to RLS, especially in the blood supply area of the anterior cerebral artery. This small demyelination of the near-cortical WMLs may be a potential marker for the right-to-left shunt of the heart. Transcranial Doppler ultrasonography may help finding more RLS in migraineurs with near-cortical WMLs.

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.

The Role of Transcranial Grayscale and Doppler Ultrasound Examination in Diagnosis of Neonatal Hypoxic-ischemic Encephalopathy

The Role of Transcranial Grayscale and Doppler Ultrasound Examination in Diagnosis of Neonatal Hypoxic-ischemic Encephalopathy

Transcranial Doppler 6 h after Successful Reperfusion as a Predictor of Infarct Volume

ObjectivesThe aim of the study is to analyze the hemodynamic changes in the middle cerebral artery (MCA) after endovascular revascularization in acute ischemic stroke (AIS) due to large vessel occlusion and its association with the infarct volume size in the control head CT. Materials and MethodsProspective study of patients with AIS due to internal carotid artery terminus or M1 segment of the MCA occlusion, who underwent endovascular treatment with a final TICI 2b-3 score, without concomitant stenosis ≥50% in both cervical carotid arteries. Transcranial Doppler ultrasound (TCD) of both MCAs was carried out at 6 h after the endovascular procedure. Mean flow velocities (MFV) after arterial reperfusion and its association with the infarct volume size in 24−36 h control head CT were determined. Results91 patients (51 women) were included with a median age of 78 years and National institute of Health Stroke Scale of 18. The MCA was occluded in 76.92%, and intravenous thrombolysis was administered in 40.7%. The incidence of symptomatic intracranial hemorrhage was 5.5%. At three months, mortality was 19.8% and a 52.7% of patients achieved functional independence (modified Rankin Scale 0-2). After a multivariable logistic regression analysis, an increase in the MFV greater than 50% at 6 h in the treated MCA compared to contralateral MCA, was an independent predictor of large infarct volume in the control head CT with an OR 9.615 (95%CI: 1.908−47.620), p=0.006 ConclusionsIncreased MFV assessed by TCD examination following endovascular recanalization is independently associated with larger infarct volume

Sociodemographic and Biomedical Correlates of Developmental Delay in 2- and 4-Year-Olds with Sickle Cell Disease.

Developmental delay occurs frequently in sickle cell disease (SCD). Psychosocial and biomedical factors contribute to delays, but most studies have not examined the timing of risk factors and developmental delay. We examined sociodemographic and biomedical factors to evaluate whether risks of developmental delay differed across 2 developmental periods. We examined Ages and Stages Questionnaire, second edition (ASQ-2), outcomes in 2-year-olds (n = 100) and 4-year-olds (n = 101) with SCD. ASQ-2 data were obtained from routine developmental screenings administered as part of health care between 2009 and 2016 at a single hematology clinic. Medical record reviews were used to identify sociodemographic and biomedical factors associated with positive screenings for developmental delay. Two-year-olds with positive ASQ-2 screenings (n = 32; 32%) were less likely to have private health insurance or to have been in formal daycare and more likely to have a severe SCD genotype. Four-year-olds with positive screenings (n = 40; 40%) were more likely to have a severe SCD genotype or an abnormal transcranial Doppler ultrasound (TCD) examination indicating high stroke risk. The strength of the association between positive screenings and insurance status, severe genotypes, and TCD examinations differed across the 2 age groups. Domain-level outcomes on the ASQ-2 also differed across the 2 age groups. The cross-sectional data indicate biomedical and psychosocial risks are related to developmental delay, but the association with specific risk factors differs across age.

Cardiac output and cerebral blood flow during carotid surgery in regional versus general anesthesia: A prospective randomized controlled study

ObjectiveCarotid endarterectomy (CEA) is a preventive procedure aimed at decreasing the subsequent risk of fatal or disabling stroke in patients with significant carotid stenosis. It is well-known that carotid surgery under ultrasound-guided regional anesthesia (US-RA) causes a significant increase in blood pressure, heart rate and stress hormone levels owing to increased sympathetic activity. However, little is known about the effects on cardiac output (CO), cardiac index (CI), and cerebral blood flow (CBF) under US-RA as compared with general anesthesia (GA). MethodsPatients scheduled for CEA were randomized prospectively to receive US-RA (n = 37) or GA (n = 41). The primary end point was the change in CI after induction of anesthesia and the change from baseline over time at four different times during the entire procedure in the respective randomized US-RA and GA groups. In addition to systolic blood pressure and heart rate, we also recorded peak systolic velocity, end-diastolic velocity, and minimum diastolic velocity as seen from transcranial Doppler ultrasound examination, as well as regional cerebral oxygenation (rSO2) as seen from near-infrared refracted spectroscopy to evaluate cerebral blood flow. ResultsIn the US-RA group, the CI increased after induction of anesthesia (3.7 ± 0.8 L/min/m2) and remained constant until the end of the procedure. In the GA group CI was significantly lower (2.4 ± 0.6 L/min/m2; P < .001). After induction of anesthesia, the rSO2 remained constant in the GA group on both the ipsilateral (63 ± 9 rSO2) and the contralateral (65 ± 7 rSO2) sides; in contrast, it significantly increased in the US-RA group (ipsilateral 72 ± 8 rSO2; P < .001; contralateral 72 ± 6 rSO2; P < .001). The transcranial Doppler ultrasound parameters (peak systolic velocity, end-diastolic velocity, and minimum diastolic velocity) did not differ between the US-RA and the GA group. The clinical outcome was similarly favorable for both groups. ConclusionsCI was maintained near baseline values throughout the procedure during US-RA, whereas a significant decrease in CI values was observed during CEA under GA. Near-infrared refracted spectroscopy values, reflecting blood flow in small vessels, were higher in US-RA patients than in those with GA. These differences did not influence clinical outcome.

P0033 / #1954: THE EFFECT OF HYPERTONIC SALINE ON INCREASED INTRACRANIAL PRESSURE IN TRAUMATIC BRAIN INJURY: PROSPECTIVE STUDY WITH NON-INVASIVE METHOD

Aims & Objectives: Transcranial Doppler (TCD) ultrasound examination is a noninvasive method for determination of intracranial pressure. The main goal of this study was to show the effectiveness of hypertonic salin infusions in reducing intracranial pressure (ICP) by using TCD ultrasound. Methods: We included all patients with mild to severe traumatic brain injury (TBI) in our intensive care unit. TCD ultrasound examinations were performed by intensivists before and after hypertonic salin infusions. We used the pulsatility index (PI) of both middle cerebral artery and optic nerve sheet diameter (ONSD) and applied the ICP equations. Results: Seventeen patients with mild to severe TBI and 12 patients in control group were included. All measurements on the TBI patients performed after a first hypertonic salin as a salvage therapy in the emergency room. The median GCSs of the patients at admission and discharge were 10 and 15 respectively. There was a significant decrease in PI after the 3rd measurement in post-hoc multiple comparisons (p=0.004). On the other hand, it was found that the decrease in ONSD became evident after the 5th measurement (p<0.0001). Eight of 17 had axonal injury findings in MRI. Two of the patients had decompressive craniectomy and none of them had died. Conclusions: The repeated hypertonic salin infusions reduce the ICP in traumatic brain injury in children and related improved GCSs. Calculation of ICP using PI and ONSD measured via TCD is a safe and fast method to determine the ICP noninvasively.

Abstract P358: Association of Kidney Function and Cerebral Arterial Stiffness

Background and Purpose: Chronic kidney disease (CKD) is known to have affected the systemic vasculature and its remodeling, which eventually led to the systemic arterial stiffness. However, the relationship between cerebral circulation and impaired renal function is poorly understood. To evaluate the effect of renal dysfunction to increase systemic and intracranial arterial stiffness, we assessed the relation between renal resistive index (RRI) and pulsatility index (PI) of the middle cerebral artery (MCA). Methods: We included patients with acute lacunar infarction. Demographic and clinical data were collected by retrospective chart review. Bilateral transcranial Doppler ultrasound (TCD) examination of the MCAs was performed using the ST3 Ultrasound system (Spencer Technologies) and PI were calculated. RRI was obtained through kidney Doppler sonography. Subjects with occlusion or significant stenosis of MCA, atrial fibrillation, bilaterally absent transtemporal sonographic windows were excluded. Results: Of the 283 included subjects (mean age 67.8 ± 10.2), 74 patients had renal dysfunction (glomerular filtration rate &lt; 60ml/min/1.73m2 at admission) and 49 patients underwent kidney Doppler ultrasound within 1 year since their acute stroke. Renal dysfunction was significantly associated with higher arterial stiffness (median PI 1.12, IQR 0.85 to 1.57 vs. controls PI 0.84, IQR 0.54 to 1.22 [p&lt;0.0001]). There was a proportional relationship between the degree of renal dysfunction and the distal vascular resistance. In multivariate adjusted regression analysis, renal function was related to high PI (p&lt;0.001). Furthermore, there is strong correlation between RRI and PI ( r =0.65, p &lt;0.001). Conclusions: In patients with lacunar infarction, renal impairment is an independent determinant of increased arterial stiffness in cerebral circulations. In addition, PI is significantly associated with RRI.

Which repetitive transcranial magnetic stimulation modality affects vasomotor reactivity in healthy subjects and how long does it last?

Objectives The aim of our study was to evaluate the effects of low and high-frequency repetitive transcranial magnetic stimulation (rTMS) on hypoxia-induced changes in bilateral cerebrovascular reserve up to 24 h in the same individuals. Methods Right-handed ten healthy male individuals participated in the study. All participants had neither drug therapy nor a concomitant disease and none of them had a variation in the circle of Willis, intracranial stenosis, arteriovenous malformation, or aneurysm which may have an impact on transcranial doppler ultrasound (TCD) examination and transcranial magnetic stimulation (TMS) recording. Results There was a statistically significant difference in the breath‐holding index (BHI) between before and after 0, 15, 30 min after 1 Hz repetitive stimulation (p < 0.05). When applying 5 Hz repetitive stimulation there was no difference before and after BHI values (p > 0.05). There were no differences in bilateral, ipsilateral, or contralateral middle cerebral artery (MCA) mean cerebral blood flow velocity (CBFV) after low or high-frequency rTMS application (p > 0.05). Conclusion The main result of the study was that low-frequency rTMS reduced vasomotor reactivity (VMR) for the very first 30 min and then this effect disappears. And the high-frequency rTMS did not affect VMR at all. Significance The effect of rTMS on VMR may continue up to 30 min but then return to the baseline and can be used safely.

Cerebral Blood Flow Velocity is Not Associated with Serum Hemoglobin in Children with Malaria-Associated Anemia.

Hemoglobin (Hbg) is often thought to impact cerebral blood flow velocity (CBFV). This study was performed to investigate the relationship between Hbg value and CBFV in African children with malaria. In this prospective, observational study, children aged 3 months to 18 years with malaria and a normal Blantyre coma score underwent a single transcranial Doppler ultrasound (TCD) examination with a concurrent Hbg check. One hundred fifty-six children with a mean age of 43 months were enrolled. Thirty-three children (21%) had severe anemia (Hbg <5g/dL), 46 (29%) had moderate anemia (Hbg 5-6.9 g/dL), 63 children (41%) had mild anemia (7-9.9 g/dL), and 14 children (9%) had no anemia (Hbg >10 g/dL) at the time of TCD examination. Mean averaged CBFV in the middle cerebral artery (MCA) for the cohort was 99% of predicted based on normative values standardized for age. There was no significant correlation between Hbg levels and measured CBFV in the MCA (r = -.09; 95% CI, -.24-.07; P = .29). In a large sample of African children with malaria, Hbg did not correlate with CBFVs as measured by TCD. Future work that includes baseline TCD measurements and Hbg values as well as other physiological parameters known to influence CBFVs is necessary to confirm these findings.

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

ObjectiveTranscarotid 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. MethodsA 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. ResultsEleven 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. ConclusionsTCD 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.

Non-invasive estimation of cerebral perfusion pressure using transcranial Doppler ultrasonography in children with severe traumatic brain injury.

ObjectiveTo identify if cerebral perfusion pressure (CPP) can be non-invasively estimated by either of two methods calculated using transcranial Doppler ultrasound (TCD) parameters.DesignRetrospective review of previously prospectively gathered data.SettingPediatric intensive care unit in a tertiary care referral hospital.PatientsTwenty-three children with severe traumatic brain injury (TBI) and invasive intracranial pressure (ICP) monitoring in place.InterventionsTCD evaluation of the middle cerebral arteries was performed daily. CPP at the time of the TCD examination was recorded. For method 1, estimated cerebral perfusion pressure (CPPe) was calculated as: CPPe = MAP × (diastolic flow (Vd)/mean flow (Vm)) + 14. For method 2, critical closing pressure (CrCP) was identified as the intercept point on the x-axis of the linear regression line of blood pressure and flow velocity parameters. CrCP/CPPe was then calculated as MAP-CrCP.Measurements and main resultsOne hundred eight paired measurements were available. Using patient averaged data, correlation between CPP and CPPe was significant (r = 0.78, p = < 0.001). However, on Bland-Altman plots, bias was 3.7 mmHg with 95% limits of agreement of − 17 to + 25 for CPPe. Using patient averaged data, correlation between CPP and CrCP/CPPe was significant (r = 0.59, p = < 0.001), but again bias was high at 11 mmHg with wide 95% limits of agreement of − 15 to + 38 mmHg.ConclusionsCPPe and CrCP/CPPe do not have clinical value to estimate the absolute CPP in pediatric patients with TBI.

Transcranial Doppler ultrasound findings in children with moderate-to-severe traumatic brain injury following abusive head trauma.

PurposeAbusive head trauma (AHT) is the leading cause of fatal head injuries for children under 2 years. The objective was to evaluate, using transcranial Doppler ultrasound (TCD), whether children with AHT have a similar neurovascular response to injury compared with children without AHT.MethodsRetrospective sub-analysis of previously prospectively acquired data in a pediatric intensive care unit in a level 1 trauma hospital. TCD was performed daily until hospital day 8, discharge, or death. Neurologic outcome was assessed using the Glasgow Outcome Scale Extended (GOS-E Peds) at 1 month from initial injury.ResultsSixty-nine children aged 1 day to 17 years with moderate-to-severe traumatic brain injury were enrolled. Fifteen children suffered AHT and 54 had no suspicion for AHT. Fifteen children with AHT underwent 80 serial TCD examinations; 54 children without AHT underwent 308 exams. After standardization for age and gender normative values, there was no statistically significant difference in mean cerebral blood flow velocity of the middle cerebral artery (VMCA) between children with and without AHT. There was no difference in the incidence of extreme cerebral blood flow velocity (CBFV, greater or less than 2 standard deviations from normative value) between groups. Within the AHT group, there were no statistically significant differences in VMCA between children with a favorable (GOS-E Peds 1–4) versus unfavorable neurologic outcome (GOS-E Peds 5–8).ConclusionChildren with AHT have no significant differences in VMCA or percentage of extreme CBFV in the middle cerebral artery compared to with those without AHT.

Transcranial Doppler Ultrasonography Provides Insights into Neurovascular Changes in Children with Cerebral Malaria

To evaluate neurovascular changes in pediatric patients with cerebral malaria. African children with cerebral malaria were enrolled and underwent daily transcranial Doppler ultrasound (TCD) examinations through hospital day 8, discharge, or death. Neurologic outcomes were assessed 2 weeks after enrollment. In total, 160 children with cerebral malaria and 155 comparison patients were included. In patients with cerebral malaria, TCD flow changes characterized as hyperemia were seen in 42 (26%), low flow in 46 (28%), microvascular obstruction in 35 (22%), cerebral vasospasm in 21 (13%), and isolated posterior hyperemia in 7 (4%). Most had a single neurovascular phenotype observed throughout participation. Among comparison patients, 76% had normal TCD findings (P < .001). Impaired autoregulation was present in 80% of cases (transient hyperemic response ratio 1.01 ± 0.03) but improved through day 4 (1.1 ± 0.02, P = .014). Overall mortality was 24% (n = 39). Neurologic deficits were evident in 21% of survivors. Children meeting criteria for vasospasm were most likely to survive with sequelae, and children meeting criteria for low flow were most likely to die. Autoregulation was better in children with a normal neurologic outcome (1.09, 95% CI 1.06-1.12) than in others (0.98, 95% CI 0.95-1) (P ≤ .001). Several distinct changes in TCD measurements were identified in children with cerebral malaria that permitted phenotypic grouping. Groups had distinct associations with neurologic outcomes. Validation of pathogenic mechanisms associated with each phenotype may aid in developing TCD as a portable, easy-to-use tool to help guide targeted adjunctive therapy in cerebral malaria aimed at causative mechanisms of injury on an individual level.

An augmented-reality system prototype for guiding transcranial Doppler ultrasound examination

Ultrasound (US) is a popular medical imaging technique in the clinic due to its low cost, high portability, and real-time diagnostic value. A special type of ultrasound technique, transcranial Doppler (TCD) ultrasound can be used to measure blood flows in cerebral blood vessels through acoustic bone windows of the intact human skull. Although TCD ultrasound is commonly used to diagnose and monitor a range of neurovascular conditions, such as stroke, interpretation of the image content in the TCD scans and quick localization of the targeted blood vessels with it can be difficult due to inherent challenges of its unique image contrasts, relatively low image quality, and 2D nature of the technique in relation to the 3D brain anatomy that is invisible to the clinician. These drawbacks may hinder the efficiency and even accuracy of the TCS examinations, especially for novel users. To render the procedure more efficient and intuitive, we developed a prototype of augmented-reality system to guide the procedure by fusing a population-averaged probabilistic blood vessel atlas with camera footages of the patient. The system prototype was demonstrated with healthy subjects, and is expected to facility the clinical TCD examination, as well as to help in the educational context for new clinicians and clinical technicians.