Noninvasive detection of diffuse intracranial disease

Close relationships between neck and upper-back stiffness and transverse cervical artery flow velocity

PURPOSE

Neck and upper-back stiffness is encountered in daily life, with symptoms appearing as dullness or aches predominantly in the trapezius muscle (TM). Our previous study demonstrated that TM hardness as measured with a muscle hardness meter correlates well with transverse cervical artery (TCA) flow supplying the TM. Muscle hardness meters, however, cannot measure hardness in the TM alone. Meanwhile, recent advances in ultrasound elastography have enabled the evaluation of localized hardness in targeted tissues. The present study, therefore, aimed to clarify the relationship between TM hardness as measured by elastography and TCA hemodynamics as measured on Doppler sonography, with reference to daily symptoms of upper-back stiffness.

METHODS

The study population comprised 66 healthy young adults (32 males, 34 females; mean age, 21 ± 1 years). Relationships were evaluated between TM hardness as a negative correlate of strain ratio from elastography and TCA hemodynamics on Doppler sonography. Hemodynamics in the TCA were evaluated according to the frequency of neck and upper-back stiffness.

RESULTS

TM strain ratio correlated with peak systolic velocity (PSV) in the TCA (r = 0.273, p = 0.036), particularly in symptomatic subjects (r = 0.417, p = 0.022). PSV in the TCA decreased with increasing frequency of daily symptoms (p = 0.045).

CONCLUSION

TCA hemodynamics correlated with muscle hardness when evaluating localized TM hardness. This relationship and low PSV in the TCA were evident in symptomatic subjects. These results suggest that PSV in the TCA is associated with neck and upper-back stiffness.

Optimizing the prediction of sepsis-associated encephalopathy with cerebral circulation time utilizing a nomogram: a pilot study in the intensive care unit

Background

Sepsis-associated encephalopathy (SAE) is prevalent in intensive care unit (ICU) environments but lacks established treatment protocols, necessitating prompt diagnostic methods for early intervention. Traditional symptom-based diagnostics are non-specific and confounded by sedatives, while emerging biomarkers like neuron-specific enolase (NSE) and S100 calcium-binding protein B (S100B) have limited specificity. Transcranial Doppler (TCD) indicators, although is particularly relevant for SAE, requires high operator expertise, limiting its clinical utility.

Objective

This pilot study aims to utilize cerebral circulation time (CCT) assessed via contrast-enhanced ultrasound (CEUS) as an innovative approach to investigate the accuracy of SAE prediction. Further, these CCT measurements are integrated into a nomogram to optimize the predictive performance.

Methods

This study employed a prospective, observational design, enrolling 67 ICU patients diagnosed with sepsis within the initial 24 h. Receiver operating characteristic (ROC) curve analyses were conducted to assess the predictive accuracy of potential markers including NSE, S100B, TCD parameters, and CCT for SAE. A nomogram was constructed via multivariate Logistic Regression to further explore the combined predictive potential of these variables. The model's predictive performance was evaluated through discrimination, calibration, and decision curve analysis (DCA).

Results

SAE manifested at a median of 2 days post-admission in 32 of 67 patients (47.8%), with the remaining 35 sepsis patients constituting the non-SAE group. ROC curves revealed substantial predictive utility for CCT, pulsatility index (PI), and S100B, with CCT emerging as the most efficacious predictor, evidenced by an area under the curve (AUC) of 0.846. Multivariate Logistic Regression identified these markers as independent predictors for SAE, leading to the construction of a nomogram with excellent discrimination, substantiated by an AUC of 0.924 through bootstrap resampling. The model exhibited satisfactory concordance between observed and predicted probabilities, and DCA confirmed its clinical utility for the prompt identification of SAE.

Conclusion

This study highlighted the enhanced predictive value of CCT in SAE detection within ICU settings. A novel nomogram incorporating CCT, PI, and S100B demonstrated robust discrimination, calibration, and clinical utility, solidifying it as a valuable tool for early SAE intervention.

The TCD hyperemia index to detect vasospasm and delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Elevated mean flow velocity (MFV) on transcranial Doppler (TCD) is used to predict vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Hyperemia should be considered when observing elevated MFV. Lindegaard ratio (LR) is commonly used but does not enhance predictive values. We introduce a new marker, the hyperemia index (HI), calculated as bilateral extracranial internal carotid artery MFV divided by initial flow velocity.

METHODS

We evaluated SAH patients hospitalized ≥7 days between December 1, 2016 and June 30, 2022. We excluded patients with nonaneurysmal SAH, inadequate TCD windows, and baseline TCD obtained after 96 hours from onset. Logistic regression was conducted to assess the significant associations of HI, LR, and maximal MFV with vasospasm and delayed cerebral ischemia (DCI). Receiver operating characteristic analyses were employed to find the optimal cutoff value for HI.

RESULTS

Lower HI (odds ratio [OR] 0.10, 95% confidence interval [CI] 0.01-0.68), higher MFV (OR 1.03, 95% CI 1.01-1.05), and LR (OR 2.02, 95% CI 1.44-2.85) were associated with vasospasm and DCI. Area under the curve (AUC) for predicting vasospasm was 0.70 (95% CI 0.58-0.82) for HI, 0.87 (95% CI 0.81-0.94) for maximal MFV, and 0.87 (95% CI 0.79-0.94) for LR. The optimal cutoff value for HI was 1.2. Combining HI <1.2 with MFV improved positive predictive value without altering the AUC value.

CONCLUSIONS

Lower HI was associated with a higher likelihood of vasospasm and DCI. HI <1.2 may serve as a useful TCD parameter to indicate vasospasm and DCI when elevated MFV is observed, or when transtemporal windows are inadequate.

Development and Validation of Machine Learning Models to Classify Artery Stenosis for Automated Generating Ultrasound Report

Duplex ultrasonography (DUS) is a safe, non-invasive, and affordable primary screening tool to identify the vascular risk factors of stroke. The overall process of DUS examination involves a series of complex processes, such as identifying blood vessels, capturing the images of blood vessels, measuring the velocity of blood flow, and then physicians, according to the above information, determining the severity of artery stenosis for generating final ultrasound reports. Generation of transcranial doppler (TCD) and extracranial carotid doppler (ECCD) ultrasound reports involves a lot of manual review processes, which is time-consuming and makes it easy to make errors. Accurate classification of the severity of artery stenosis can provide an early opportunity for decision-making regarding the treatment of artery stenosis. Therefore, machine learning models were developed and validated for classifying artery stenosis severity based on hemodynamic features. This study collected data from all available cases and controlled at one academic teaching hospital in Taiwan between 1 June 2020, and 30 June 2020, from a university teaching hospital and reviewed all patients' medical records. Supervised machine learning models were developed to classify the severity of artery stenosis. The receiver operating characteristic curve, accuracy, sensitivity, specificity, and positive and negative predictive value were used for model performance evaluation. The performance of the random forest model was better compared to the logistic regression model. For ECCD reports, the accuracy of the random forest model to predict stenosis in various sites was between 0.85 and 1. For TCD reports, the overall accuracy of the random forest model to predict stenosis in various sites was between 0.67 and 0.86. The findings of our study suggest that a machine learning-based model accurately classifies artery stenosis, which indicates that the model has enormous potential to facilitate screening for artery stenosis.

Neck-brain integrated ultrasound as a noninvasive screening tool to identify morphological features of middle cerebral artery disease

BACKGROUND AND AIMS

Endovascular treatment is suitable for middle cerebral artery (MCA) with focal lesion. Therefore, accurate evaluation of the morphological features of MCA disease is critical. Ultrasonography is commonly used to screen for MCA lesions. However, there are few studies on lesion length. Using ultrasonography, we aimed to prospectively evaluate MCA disease with focal stenosis, long stenosis, focal occlusion, and long occlusion.

METHODS

Patients with symptomatic MCA disease scheduled for digital subtraction angiography were enrolled. The ultrasonic parameters recorded included mean flow velocity at MCA (V_MCA) and extracranial internal carotid artery (V_ICA), bilateral V_MCA ratio, bilateral V_ICA ratio, and MCA flow continuity.

RESULTS

A total of 278 MCAs were included. Compared to normal vessels, the bilateral V_MCA ratio increased in the focal stenosis group and decreased in the long lesion and focal occlusion groups (all p < 0.05); the V_ICA and bilateral V_ICA ratio decreased in the long lesion group (all p < 0.01), and there was no significant difference in the focal lesion group (all p > 0.05). The optimal cut-offs were bilateral V_MCA ratio <0.80 to predict long lesions and focal occlusions (sensitivity: 0.898, specificity: 0.975), and bilateral V_ICA ratio <0.84 to predict long lesions (sensitivity: 0.704, specificity: 0.879). The sensitivity and specificity to predict long occlusions were 96.7% and 94.8%, respectively, in the absence of MCA flow continuity.

CONCLUSIONS

Neck-brain integrated ultrasound is an appropriate screening method for identifying MCA lesions with different morphologies. Endovascular treatment might not be recommended when bilateral V_ICA ratio <0.84 in patients with MCA lesions.

Accuracy of transcranial Doppler in detecting intracranial stenosis in patients with sickle cell anemia when compared to magnetic resonance angiography

BACKGROUND

Stroke, the most devastating consequence of sickle cell anemia (SCA), is associated with endothelial damage and intracranial artery stenosis. We aimed to assess transcranial Doppler (TCD) ultrasound accuracy in detecting intracranial stenosis when compared to magnetic resonance angiography (MRA).

METHODS

Children with SCA and at least one TCD and MRA within 1 month were identified from a retrospectively collected database. Sensitivity and specificity were obtained to assess the overall accuracy of TCD mean flow velocity (mFV) ≥200 cm/s in detecting vessel stenosis of ≥50%. Multivariate analysis identified independent factors associated with MRA stenosis.

RESULTS

Among 157 patients in the database, 64 had a TCD and MRA within 1 month (age 11.8 ± 5.3 years, 56% female, 20% with cerebral infarcts on MRI, 8 or 13% had mFV ≥200 cm/s and 20% or 21%, had intracranial stenosis ≥50% on MRA). TCD mFV ≥200 cm/s had a high specificity (95%) but low sensitivity (29%) to detecting intracranial stenosis. As a continuous variable, TCD mFV of 137.5 cm/s had maximal specificity (77%) and sensitivity (72%). After adjustment for age, hemoglobin level, transfusion status, hydroxyurea treatment, and vessel, for every increase in cm/sec on TCD, there was a 2% increase in the odds of ≥50% stenosis on MRA (p < 0.001).

CONCLUSION

Our study reports TCD mFV is a positive predictor of MRA stenosis in SCA, independent of patient characteristics, including hemoglobin. A mFV ≥200 cm/s is highly specific but less sensitive in detecting stenosis ≥50%. Lower mFV cut points may be needed for the early detection of intracranial stenosis.

Non-invasive Detection of Diffuse Intracranial Vertebrobasilar Artery Stenosis: A Prospective Comparison with Digital Subtraction Angiography

The aim of this study was to prospectively evaluate diffuse intracranial vertebrobasilar artery stenosis by ultrasonic examination with digital subtraction angiography as the reference. Five hundred forty-one vertebrobasilar arteries with a normal lumen or intracranial stenosis were enrolled. Peak systolic velocity, mean flow velocity and end-diastolic velocity (EDV) at the intracranial vertebrobasilar arteries and extracranial vertebral arteries (VAs) were measured. The resistance index (RI) at extracranial VAs and the difference between the RI of extracranial VAs and the RI of the extracranial internal carotid artery (RI_ica) were calculated. Compared with normal arteries, all stenotic arteries were divided into the high-velocity group (focal stenosis, multiple-segment stenosis and multiple-artery stenosis) and low-velocity group (critical stenosis and long stenosis). The consistency between ultrasonic examination and digital subtraction angiography for evaluation of vertebrobasilar arteries with multiple-segment stenosis and multiple-artery stenosis was not favorable when applying the widely used Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis criteria (κ = 0.442 and 0.438, respectively). The optimal low-velocity criteria for identifying intracranial vertebrobasilar arteries with critical stenosis and long stenosis were determined by receiver operating characteristic curve analysis and were as follows: EDV ≤15 cm/s and RI ≥0.68 at the extracranial VA and RIica ≥0.10.

Peripheral Vascular Resistance in Cerebral Arteries in Patients With Carotid Atherosclerosis - Substudy Results of the Atherosclerotic Plaque Characteristics Associated With a Progression Rate of the Plaque and a Risk of Stroke in Patients With the Carotid Bifurcation Plaque Study (ANTIQUE)

OBJECTIVES

Transcranial color-coded duplex sonography (TCCS) enables to measure blood flow characteristics in cerebral vessels, including vascular resistance and pulsatility. The study aims to identify factors influencing pulsatility (PI) and resistance (RI) indices measured using TCCS in patients with carotid atherosclerosis.

METHODS

Self-sufficient patients with atherosclerotic plaque causing 20-70% carotid stenosis were consecutively enrolled to the study. All patients underwent duplex sonography of cervical arteries and TCCS with measurement of PI and RI in the middle cerebral artery, neurological, and physical examinations. Following data were recorded: age, gender, height, weight, body mass index, systolic and diastolic blood pressure, occurrence of current and previous diseases, surgery, medication, smoking, and daily dose of alcohol. Univariant and multivariant logistic regression analysis were used for identification of the factors influencing RI and PI.

RESULTS

Totally 1863 subjects were enrolled to the study: 139 healthy controls (54 males, age 55.52 ± 7.05 years) in derivation cohort and 1724 patients (777 males, age 68.73 ± 9.39 years) in validation cohort. The cut off value for RI was 0.63 and for PI 1.21. Independent factors for increased RI/PI were age (odds ratio [OR] = 1.108/1.105 per 1 year), occurrence of diabetes mellitus (OR = 1.767/2.170), arterial hypertension (OR = 1.700 for RI only), width of the carotid plaque (OR = 1.260 per 10% stenosis for RI only), and male gender (OR = 1.530 for PI only; P ˂.01 in all cases).

CONCLUSIONS

The independent predictors of increased cerebral arterial resistance and/or pulsatility in patients with carotid atherosclerosis were age, arterial hypertension, diabetes mellitus, carotid plaque width, and male gender.

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.

Transcranial Doppler study in acute spontaneous intracerebral hemorrhage: The role of pulsatility index

Objective

Pulsatility index (PI) is a parameter calculated by transcranial Doppler sonography (TCD), which is commonly used for patients with subarachnoid hemorrhage or ischemic stroke. However, we performed a retrospective analysis of patients with acute spontaneous intracerebral hemorrhage (ICH) to assess the function of TCD, particularly the PI.

Methods

This study involved a total of 46 patients with acute ICH who received treatment at a single center between May 2013 and December 2014. Medical records of baseline characteristics, except for the modified Rankin scale, were obtained at initial evaluation in the emergency room, and TCD was used to calculate middle cerebral artery flow velocity (MFV) and PI at admission (baseline), 24 h, and 7 days. The PI and MFV values on the affected middle cerebral artery were compared with those on the contralateral side. Linear regression analysis was used for statistical analyses (SPSS 21.0, IBM Corp., Armonk, NY, USA).

Results

Statistical analysis indicated that sex, age, Glasgow coma scale, intraventricular hemorrhage, and hematoma size were not correlated with PI (p＞0.05); however, only PI was positively correlated with functional outcome at 6 months after treatment (R=0.846, p=0.002).

Conclusions

These results provide evidence that the parameter of PI is an independent determinant prognostic factor in acute spontaneous ICH. Further research is needed to investigate the influence of cerebral blood flow dynamics on a larger, more controlled, and more randomized basis.

Transcranial Doppler ultrasonography (uses, limitations, and potentials): a review article

Background

The additional information that transcranial Doppler can provide as part of a multimodal imaging protocol in many clinical settings has not been evaluated.

Main body

Transcranial Doppler is a bedside procedure used to assess cerebral blood flow velocity via cerebral circulation and pulsatility index (PI). Many diseases can lead to cerebral vessels vasospasm as in subarachnoid hemorrhage and trauma. Cerebral vessels vasospasm represented by abnormal elevation of cerebral blood flow velocity. Intracranial pressure can be monitored by pulsatility index which reflects blood flow resistance in cerebral vessels. Transcranial Doppler ultrasonography is also the unique modality for detection of micro emboli in high-risk patients. Also, it can be used for evaluation of circulatory arrest with subsequent confirmation of brain death

Conclusion

Transcranial Doppler ultrasonography is the only diagnostic modality that provides a reliable assessment of cerebral blood flow patterns in real time. The physiological information obtained from TCD is complementary to the anatomical details obtained from other neuroimaging modalities. TCD is relatively cheap, can be performed bedside, and allows monitoring in acute emergency settings.

Determination of cerebral blood flow velocity and microembolic signals in essential thrombocytosis by transcranial doppler ultrasonography

OBJECTIVES

The goal of treatment in essential thrombocytosis (ET) is to prevent vascular complications such as thrombosis and hemorrhage. This study aimed to evaluate the risk of cerebrovascular microembolism in ET patients due to detection of microembolic signals (MES) and measure cerebral blood flow velocity (CBFV) by Transcranial Doppler (TCD) ultrasonography.

MATERIAL AND METHODS

In this prospective case-control study, forty patients with diagnosed ET and age and sex-matched forty healthy controls were examined by the TCD sonography.

RESULTS

The ET group had a higher rate of MES (8/40) in the right MCA than that in the control group (none), as measured by TCD. Five patients had MES at the left MCA compared to that in no subjects in the control group. The comparison of the ET and control groups in terms of CBFV parameters showed significantly lower end-diastolic FV at the right MCA in the ET group compared to that in the control group (p < 0.05). On the other hand; both pulsatility and resistance indices in the right and left MCA and the ratios of systolic to diastolic blood flow rates in the right and left MCA were significantly higher in the ET group than that in the control group.

DISCUSSION

This study revealed that MES seems to be more common in patients with ET despite treatment. We could suggest that ET patients should be monitored more closely to address the potential risk of developing a cerebrovascular disease, which can be estimated by detection MES and raised CBFV, combine antiplatelet therapies to standard treatments.

Predictors of the pulsatility index in the middle cerebral artery of acute stroke patients

Cervical and transcranial Doppler (TCD) are widely used as non-invasive methods in the evaluation of acute ischemic stroke (AIS) patients. High-grade carotid artery stenosis induces haemodynamic changes such as collateral flow and a so-called post-stenotic flow pattern of the middle cerebral artery (MCA), which appears flattened, with a reduction of the velocity difference between systole and diastole. We studied the influence of carotid artery stenosis and other variables on the flow pattern in the MCA using the pulsatility index (PI), a quantitative TCD parameter reflecting the flow spectrum in a large of cohort AIS patients. We performed ultrasound examinations of 1825 AIS patients at the CHUV from October 2004 to December 2014. We extracted patient characteristics from the ASTRAL registry. Carotid stenosis severity was classified as < 50%, 50–70%, 70–90% and > 90%, or occlusion, according to Doppler velocity criteria. We first determined variables associated with stenosis grade. Then we performed a multivariate analysis after adjusting for baseline differences, using MCA PI as dependent variable. Carotid stenosis > 70% (− 0.07) and carotid stenosis > 90%, or occlusion (− 0.14) and left side (− 0.02) are associated with lower MCA PI values. Age (+0.006 PI units per decade), diabetes (+0.07), acute ischemic changes on initial CT (+0.03) and severe plaque morphology (+0.18) are associated with higher MCA PI values. We found a number of clinical and radiological conditions that significantly influence the PI of the MCA, including high-grade ipsilateral carotid stenosis in AIS patients. We provide for the first time a quantitative evaluation of the effect of these influencing factors from a large cohort of AIS patients.

Cerebral Small Vessel, But Not Large Vessel Disease, Is Associated With Impaired Cerebral Autoregulation During Cardiopulmonary Bypass: A Retrospective Cohort Study

BACKGROUND

Impaired cerebral blood flow (CBF) autoregulation during cardiopulmonary bypass (CPB) is associated with stroke and other adverse outcomes. Large and small arterial stenosis is prevalent in patients undergoing cardiac surgery. We hypothesize that large and/or small vessel cerebral arterial disease is associated with impaired cerebral autoregulation during CPB.

METHODS

A retrospective cohort analysis of data from 346 patients undergoing cardiac surgery with CPB enrolled in an ongoing prospectively randomized clinical trial of autoregulation monitoring were evaluated. The study protocol included preoperative transcranial Doppler (TCD) evaluation of major cerebral artery flow velocity by a trained vascular technician and brain magnetic resonance imaging (MRI) between postoperative days 3 and 5. Brain MRI images were evaluated for chronic white matter hyperintensities (WMHI) by a vascular neurologist blinded to autoregulation data. "Large vessel" cerebral vascular disease was defined by the presence of characteristic TCD changes associated with stenosis of the major cerebral arteries. "Small vessel" cerebral vascular disease was defined based on accepted scoring methods of WMHI. All patients had continuous TCD-based autoregulation monitoring during surgery.

RESULTS

Impaired autoregulation occurred in 32.4% (112/346) of patients. Preoperative TCD demonstrated moderate-severe large vessel stenosis in 67 (25.2%) of 266 patients with complete data. In adjusted analysis, female sex (odds ratio [OR], 0.46; 95% confidence interval [CI], 0.25-0.86; P = .014) and higher average temperature during CPB (OR, 1.23; 95% CI, 1.02-1.475; P = .029), but not moderate-severe large cerebral arterial stenosis (P = .406), were associated with impaired autoregulation during CPB. Of the 119 patients with available brain MRI data, 42 (35.3%) demonstrated WMHI. The presence of small vessel cerebral vascular disease was associated with impaired CBF autoregulation (OR, 3.25; 95% CI, 1.21-8.71; P = .019) after adjustment for age, history of peripheral vascular disease, preoperative hemoglobin level, and preoperative treatment with calcium channel blocking drugs.

CONCLUSIONS

These data confirm that impaired CBF autoregulation is prevalent during CPB predisposing affected patients to brain hypoperfusion or hyperperfusion with low or high blood pressure, respectively. Small vessel, but not large vessel, cerebral vascular disease, male sex, and higher average body temperature during CPB appear to be associated with impaired autoregulation.

The relative effects of dexmedetomidine and propofol on cerebral blood flow velocity and regional brain oxygenation: A randomised noninferiority trial

BACKGROUND

Dexmedetomidine constricts cerebral blood vessels without a concomitant reduction in cerebral metabolic oxygen consumption. Its safety as a sedative in patients with neurological diseases thus remains uncertain.

OBJECTIVE

Our primary objective was to test the hypothesis that dexmedetomidine is noninferior to propofol as regards cerebral blood flow (CBF) velocity and brain oxygenation.

DESIGN

Unblinded randomised trial.

SETTING

Cleveland Clinic Hospital, Cleveland, from November 2010 to July 2013.

PATIENTS

Forty-four patients scheduled for insertion of a deep-brain stimulating electrodes.

INTERVENTIONS

Patients were randomised to receive either dexmedetomidine or propofol sedation during deep-brain stimulating electrode insertion.

MAIN OUTCOME MEASURES

Intraoperative CBF velocity was measured with transcranial Doppler, and brain oxygenation was assessed with near-infrared spectroscopy. Noninferiority of dexmedetomidine to propofol was defined as a less than 20% difference in means.

RESULTS

Twenty-three patients were given dexmedetomidine and 21 propofol. Baseline characteristics and operative management were similar in each group. Dexmedetomidine was noninferior to propofol on both CBF and brain oxygenation, confirming our primary hypothesis. For cerebral flood flow, the estimated ratio of means (dexmedetomidine/propofol) was 0.94 [90% CI: 0.84 to 1.05], P = 0.011 for noninferiority. For brain oxygenation, the estimated ratio of means was 0.99 [90% CI: 0.96 to 1.02], P < 0.001 for noninferiority. Superiority was not found for either primary outcome. Dexmedetomidine provided deeper sedation than propofol, with a difference of medians of 1 [90% CI: 0 to 2], P < 0.001 on the Observer's Assessment of Alertness/Sedation scale. No significant differences were observed in pulsatility index, cerebral perfusion pressure, number of hypertensive or apnoeic episodes.

CONCLUSION

Regional brain oxygenation and CBF velocity are comparably preserved during dexmedetomidine and propofol sedation. Thus, the use of dexmedetomidine in patients with movement disorders appears reasonable.

TRIAL REGISTRATION

The trial was registered at ClinicalTrials.gov (NCT 01200433).

Extracranial and Intracranial Ultrasonographic Findings in Posterior Circulation Infarction

OBJECTIVES

Patients with posterior circulation infarction are at higher risk of early recurrent stroke, especially those with vertebrobasilar stenosis or hypoplasia. The clinical presentations of this condition vary over a broad range, making diagnosis and treatment a challenge. Hemodynamic changes and stenosis detected by ultrasonography (US) are sensitive and important indicators for further evaluation. In this study, we correlated extracranial and intracranial US characteristics with brain magnetic resonance imaging (MRI) in patients with posterior circulation infarction.

METHODS

Inpatients with acute ischemic stroke who received both MRI and US were enrolled. Baseline characters, underlying disorders, the ischemic territory, and vascular stenosis on MRI were recorded. Series of US data, including flow volume, diameter, mean velocity, and pulsatility index, were analyzed. Patients with new infarction over the medulla, pons, midbrain, or cerebellum were enrolled as the posterior circulation infarction group. Patients with pure anterior circulation infarction were also enrolled.

RESULTS

A total of 210 patients with anterior circulation infarction (mean age ± SD, 66.24 ± 12.88 years) and 143 with posterior circulation infarction (mean age, 65.82 ± 11.39 years) were enrolled. Significant higher frequencies of vertebral artery hypoplasia and decreased intracranial vertebrobasilar velocity in the posterior circulation infarction group (44.75% and 64.33%, respectively) were documented (P < .0001; P = .035). Ischemic lesion distributions were correlated with vertebral artery hypoplasia (55.56 %) and low vertebral and basilar artery velocities (44.44% and 25.53%), as documented by US. A low vertebrobasilar velocity was highly correlated with MRI-documented vascular stenosis (53.06%).

CONCLUSIONS

Vertebral artery hypoplasia and a low velocity in the intracranial vertebrobasilar system on US might change the treatment of patients with posterior circulation infarction for primary and secondary prevention.

The Assessment of Diagnostic Accuracy for Basilar Artery Stenosis by Transcranial Color-Coded Sonography

This study aimed to determine the optimal criteria for evaluating basilar artery stenosis (BAS) by transcranial color-coded sonography (TCCS). A total of 403 cases with both TCCS and digital subtraction angiography (DSA) were enrolled. Peak systolic velocity (PSV), end diastolic velocity (EDV) and mean flow velocity (MFV) of the basilar artery (BA), intracranial vertebral artery (IVA) and posterior cerebral artery (PCA) were measured. The ratios PSV_BA/PSV_IVA and PSV_BA/PSV_PCA were calculated. With DSA as the reference, the optimal criteria for grading BAS were determined by receiver operating characteristic analysis. They were as follows: PSV ≥110 cm/s, MFV ≥70 cm/s and PSV_BA/PSV_IVA ≥1.5 for <50% BAS; PSV ≥150 cm/s, MFV ≥90 cm/s and PSV_BA/PSV_IVA ≥2.0 for 50%-69% BAS; PSV ≥210 cm/s, MFV ≥120 cm/s and PSV_BA/PSV_IVA ≥3.0 for 70%-99% BAS. The combination of PSV, MFV and PSV_BA/PSV_IVA may increase the accuracy for diagnosing 70%-99% BAS.

Assessment of cerebral circulation in a porcine model of intravenously given E. coli induced fulminant sepsis

BACKGROUND

The aim of the present work was to assess cerebral hemodynamic changes in a porcine model of E.coli induced fulminant sepsis.

METHODS

Nineteen healthy female Hungahib pigs, 10-12 weeks old, randomly assigned into two groups: Control (n = 9) or Septic Group (n = 10). In the Sepsis group Escherichia coli culture suspended in physiological saline was intravenously administrated in a continuously increasing manner according to the following protocol: 2 ml of bacterial culture suspended in physiological saline was injected in the first 30 min, then 4 ml of bacterial culture was administered within 30 min, followed by infusion of 32 ml bacterial culture for 2 h. Control animals received identical amount of saline infusion. Systemic hemodynamic parameters were assessed by PiCCo monitoring, and cerebral hemodynamics by transcranial Doppler sonography (transorbital approach) in both groups.

RESULTS

In control animals, systemic hemodynamic variables and cerebral blood flow velocities and pulsatility indices were relatively stable during the entire procedure. In septic animals shock developed in 165 (IQR: 60-255) minutes after starting the injection of E.coli solution. Blood pressure values gradully decreased, whereas pulse rate increased. A decrease in cardiac index, an increased systemic vascular resistance, and an increased stroke volume variation were observed. Mean cerebral blood flow velocity in the middle cerebral artery did not change during the procedure, but pulsatility index significantly increased.

CONCLUSIONS

There is vasoconstriction at the level of the cerebral arterioles in the early phase of experimental sepsis that overwhelmes autoregulatory response. These results may serve as additional pathophysiological information on the cerebral hemodynamic changes occurring during the septic process and may contribute to a better understanding of the pathomechanism of septic encephalopathy.

Impaired cerebrovascular responsiveness and cognitive performance in adults with type 2 diabetes

AIM

Cognitive deficits in type 2 diabetes mellitus (T2DM) may be partly attributable to stiffness in cerebral arteries and impaired vasodilator function, limiting the ability to increase blood flow in brain regions to meet cognitive demands. We undertook a comparison of cerebrovascular responsiveness (CVR) and cognitive performance in adults with and without T2DM.

METHODS

Older adults with (50) and without (Herath, Cherbuin, Eramudugolla, & Anstey, 2016) T2DM underwent transcranial Doppler ultrasound measurements of basal cerebral mean blood flow velocity (MBFV) and pulsatility index (PI), a measure of arterial stiffness, in the middle cerebral arteries (MCA). A battery of tasks assessing domains of working memory, executive function and information processing/motor speed was then administered while MBFV was recorded. CVR to cognitive tasks was calculated as a percentage increase in MBFV from the basal level.

RESULTS

There was no difference in basal MBFV between groups. However, PI was 14% higher in the T2DM group (P<0.05), who performed poorer across all cognitive domains assessed and displayed poorer CVR in three tasks. Cognitive performance was inversely related to the PI/MBFV ratio, an indicator of intracranial stenosis.

DISCUSSION

Impaired cerebral perfusion during mental tasks is accompanied by poor cognitive performance and stiffness in the cerebral vessels.

Role of Transcranial Doppler in the Evaluation of Vasculopathy in Tuberculous Meningitis

Background

Vascular complications are important causes of cerebral infarction in tuberculous meningitis (TBM).Transcranial Doppler ultrasonography (TCD) is a non-invasive tool that can provide real-time information about cerebral hemodynamics. However, the literature on the role of TCD in the diagnosis or monitoring of vasculopathy associated with TBM is scarce. We explored the role of TCD in the diagnosis and monitoring of TBM-related vasculopathy of the major intracranial arteries.

Methods

Consecutive patients with TBM admitted to our tertiary center between 2011 and 2015 were included. All patients underwent TCD evaluation within 2 weeks of hospitalisation and it was repeated 2 weeks later. Mean flow velocity (Vmean) and pulsatility index (PI) were recorded. Flow velocities obtained from the submandibular internal carotid artery were also measured to calculate the Lindegaard ratio. A correlation was made between the patients who demonstrated vasculopathy on TCD, and patients with confirmed focal narrowing on computed tomography angiography (CTA) or magnetic resonance angiography (MRA). The modified Rankin scale (mRS) was used to assess the clinical outcome at three and six months.

Results

A total of 36 patients were recruited. Focally elevated flow velocities in the middle cerebral artery (MCA) were observed in 11 (30.6%) patients, bilaterally in 6 of them. The Lindegaard ratio was elevated (>3) in 10 (90.9%) of them, which occurred as early as the fourth day of hospitalization and persisted as long as four months. Eighty percent of patients with TBM vasculopathy by TCD criteria, also had narrowing on CTA or MRA. Ten patients (27.8%) achieved good outcome (mRS 0–2) at 3 months, which increased to 13 (36.1%) at 6 months.

Conclusion

A considerable proportion of patients with TBM develops intracranial vasculopathy, which can be reliably diagnosed and monitored using TCD.

Hemodynamic Tandem Intracranial Lesions on Magnetic Resonance Angiography in Patients Undergoing Carotid Endarterectomy

Background

Hemodynamic tandem intracranial lesions (TILs) on intracranial magnetic resonance angiography, which develop flow dependently, have been overlooked clinically in patients undergoing carotid endarterectomy. As they represent severe baseline hemodynamic compromise at the segment, they may be associated with distinctive clinical outcomes.

Methods and Results

We assessed 304 consecutive carotid endarterectomy cases treated over 3 years. Included cases had both preoperative and postoperative intracranial 3‐dimensional time‐of‐flight magnetic resonance angiography, of which signal intensities are flow dependent, and postoperative diffusion‐weighted imaging (≤3 days following carotid endarterectomy). Preoperative TILs in the ipsilateral intracranial arteries were evaluated by the presence of nonexclusive components: focal stenosis (>50%), diffuse stenosis (>50%), and decreased signal intensities (>50%). The components showing postoperative normalization were considered hemodynamic. TILs with hemodynamic components were defined as hemodynamic TILs, while others as consistent TILs. Baseline characteristics and postoperative outcomes were analyzed among 3 groups: no TILs, consistent TILs, and hemodynamic TILs. Preoperative TILs were identified in 104 (34.2%) cases; 54 (17.8%) had hemodynamic components. Diffuse stenosis and decreased signal intensities were usually reversed postoperatively. Patients with hemodynamic TILs tended to have severe proximal carotid stenosis and recent strokes (≤14 days). For the outcome, hemodynamic TILs were independently associated with the advent of postoperative ischemic lesions on diffusion‐weighted imaging (odds ratio: 2.50; 95% CI, 1.20–5.20).

Conclusions

In patients undergoing carotid endarterectomy, a significant number of preoperative TILs demonstrated hemodynamic components, which were reversed postoperatively. The presence of such components was distinctively associated with the postoperative incidence of new ischemic lesions.

Poor cerebrovascular function is an early marker of cognitive decline in healthy postmenopausal women

INTRODUCTION

Impairment of cerebrovascular function becomes evident after menopause. No study has yet explored relationships between deficits in cerebrovascular function, cognitive performance, and mood in postmenopausal women.

METHOD

Cerebrovascular function was assessed in 80 healthy postmenopausal women by monitoring blood flow velocity (BFV) in the middle and posterior cerebral arteries using transcranial Doppler ultrasound at rest, following a hypercapnic challenge, and during performance of a cognitive test battery; the latter assessed domains of memory and executive functions. Various measures of mood (i.e., Profile of Mood States and Center for Epidemiological Studies Depression Scale) were also assessed.

RESULTS

Cerebral artery elasticity and BFV responsiveness to cognitive tests (neurovascular coupling) correlated with cognitive performance but not with depressive symptoms or mood states. Mood deficits were related to poor cognitive performance.

CONCLUSION

These results highlight the importance of adequate cerebral perfusion for optimized cognitive function in healthy postmenopausal women. Preventative strategies to attenuate accelerated cognitive decline should also consider restoring cerebrovascular function.

Transcranial Color-Coded Duplex in Acute Encephalitis: Current Status and Future Prospects

BACKGROUP AND PURPOSE

There are limited data regarding the diagnostic yield of transcranial color-coded Doppler (TCCD) in acute encephalitis. We present our preliminary observations of consecutive ultrasound evaluations in 2 patients with acute encephalitis and we review the possible diagnostic role of TCCD in such cases.

METHODS

We describe two cases of acute encephalitis that presented with aphasia and confusion and underwent repeat TCCD evaluation at baseline and after 48 hours in both patients. We also critically review the current literature regarding potential TCCD applications in acute central nervous system infections.

RESULTS

Serial TCCD evaluations revealed the following triad of abnormal findings in both patients: (i) elevated pulsatility index (PI) in the left middle cerebral artery (M1 MCA) at baseline (>1.2), (ii) increased PI in left M1 MCA by >25% in comparison to right M1 MCA, and (iii) decrease in PI in left M1 MCA by >25% at the follow-up evaluation at 48 hours. The decrease in PI in left M1 MCA coincided with symptom improvement in both patients.

DISCUSSION

The focal transient increase in left M1 MCA PI may be attributed to focally increased intracranial pressure or peripheral vasospasm of distal left MCA branches. Since there are limited reports in the literature concerning TCCD evaluation of patients with central nervous system infections, our preliminary findings require independent confirmation in a larger series of patients.

Etiology of Intracranial Arterial Stenosis: Are Transcranial Color-Coded Duplex Ultrasound and 3T Black Blood MR Imaging Complementary?

BACKGROUND

In order to differentiate between the different causes of intracranial stenosis, we compared the diagnostic results of transcranial color-coded duplex (TCCD) sonography with the recently developed 3D high-resolution black blood MR sequence.

METHODS

We studied retrospectively 20 patients referred to our hospital after acute ischemic stroke who were diagnosed with intracranial stenosis and in whom a repetitive TCCD and a 3D MR T1 FAT SAT (black blood) sequence at 3T (TR/TE 350/20 ms, FOV 160×182×120 mm, 0.4×0.4×0.4 size of pixel, 300 slices, Fat Sat spair, acquisition time 6 minutes 14) were performed. Etiological diagnosis was based on one hand on the morphological aspect of the arterial wall (black blood T1 FAT SAT sequence) and on the hemodynamic aspect (TCCD) on the other hand. Analysis of black blood T1 FAT SAT MR sequence and TCCD agreement on the etiological diagnosis was performed using sign test.

RESULTS

TCCD was performed at admission and at least at two different intervals during follow-up. Eleven patients had diffuse intracranial arterial disease and nine had involvement of a single intracranial artery. Etiology of intracranial arterial stenosis included: atheromatosis, thrombosis, vasculitis and reversible vasoconstriction syndrome. There was 80% agreement (sign test P = .0059) between these two methods.

CONCLUSIONS

These two combined imaging techniques might be promising for the differentiation of arteriosclerotic changes from stenosis of another origin, especially when follow-up TCCD studies are completed early before a possible regression of the atherosclerotic plaque that might be observed 6 months after initial diagnosis.

Increased pulsatility of the intracranial blood flow spectral waveform on transcranial Doppler does not point to peripheral arterial disease in stroke patients

BACKGROUND

Peripheral arterial disease (PAD) is common in patients with acute cerebral ischemia. Indexes of resistance derived from the systolic and diastolic velocities are routinely used in diagnostic transcranial Doppler (TCD) to detect intracranial arterial disease. We sought to explore whether these indexes can predict the presence of PAD in acute cerebral ischemia.

METHODS

We prospectively evaluated consecutive patients with acute cerebral ischemia. On TCD, peak-systolic and end-diastolic velocities in both middle cerebral and basilar arteries were manually measured to calculate pulsatility index (PI) and resistance index (RI). Increased resistance was defined as PI equal to 1.2 or more and RI equal to .75 or more. Ankle-brachial index (ABI) measurements were performed and an ABI equal to .9 or more was considered predictive of definite PAD.

RESULTS

We included 95 patients (45 male, 50 female) aged 66 ± 9 years with a median National Institutes Health Stroke Scale score of 3 (interquartile range, 8) points. The ABI was abnormal and consistent with definite PAD in 24 of 95 (25.3%; 95% confidence interval [CI], 16.4-34.2) patients. Increased PI did not differ among patients with and without PAD (20.8% vs. 28.2%, P = .60). Only 1 patient with PAD had increased RI as opposed to 4 patients without PAD (4.2% vs. 5.6%, P = 1.0). Increased PI was not found to be an independent predictor of PAD (odds ratio [OR], .68; 95% CI, .22-2.12; P = .51). Increases in both PI and RI independently predicted arterial hypertension (OR, 1.62; 95% CI, 1.19-2.21; P = .002 and OR, 3.20; 95% CI, 1.51-6.77; P = .002, respectively).

CONCLUSIONS

Our findings indicate that PAD cannot be inferred from intracranial flow parameters predictive of arterial disease and risk factors such as hypertension among patients with acute cerebral ischemia.

Diffusion tensor imaging, intracranial vascular resistance and cognition in middle-aged asymptomatic subjects

BACKGROUND

The contribution of traditional vascular risk factors to cognitive impairment and dementia is well known. However, in order to obtain possible targets for prevention of vascular cognitive impairment (VCI), it may be important to identify other early and noninvasive markers in asymptomatic middle-aged adults. The calculation of middle cerebral artery-pulsatility index (MCA-PI) is an ultrasonologic, noninvasive, validated and easily reproducible technique to assess increased distal resistance to blood flow. This study aims to assess the relationship between MCA-PI, microstructural white matter (WM) integrity and cognition in a middle-aged asymptomatic population.

METHODS

Ninety-five participants from the Barcelona-Asymptomatic Intracranial Atherosclerosis (AsIA) neuropsychology study were included. Subjects were 50-65 years old, free from dementia and without history of vascular disease. Transcranial color-coded duplex ultrasound examination was performed to assess MCA-PI as a measure of vascular resistance. WM integrity was evaluated by fractional anisotropy (FA) measurements of diffusion tensor images (DTI) acquired on a 3T-MRI. The neuropsychological battery was specifically selected to be sensitive to VCI, and included tests that were grouped into six cognitive domains: executive functioning, attention, verbal fluency, memory, visuospatial skills and psychomotor speed. A multivariate linear regression model adjusted for age, gender, years of education, diabetes and hypertension was performed.

RESULTS

MCA-PI was significantly associated with WM disintegration in different tracts (fornix, corticospinal and anterior thalamic), all p < 0.05 uncorrected. Both mean MCA-PI and mean FA of those significant tracts were independently associated with poor performance in attention, psychomotor speed, and visuospatial skills after adjustment for age, gender, years of education, and vascular risk factors (all p < 0.05). MCA-PI was independently associated with lower scores in all cognitive domains, except for visuospatial skills.

CONCLUSIONS

Our data suggest that MCA-PI may be related to WM disintegration and early vascular cognitive impairment in middle-aged subjects. Although further prospective studies are needed to provide evidence for its validity in longitudinal studies, our results support the proposal of including MCA-PI as part of clinical assessment in order to identify targets for VCI prevention.

Transcranial Doppler to assess sepsis-associated encephalopathy in critically ill patients

Background

Transcranial Doppler can detect cerebral perfusion alteration in septic patients. We correlate static Transcranial Doppler findings with clinical signs of sepsis-associated encephalopathy.

Methods

Forty septic patients were examined with Transcranial Doppler on the first and third day of sepsis diagnosis. The pulsatility index (PI) and cerebral blood flow index (CBFi) were calculated by blood velocity in the middle cerebral artery (cm/sec). Patients underwent a daily cognitive assessment with the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) test.

Results

Twenty-one patients (55%) were found to present confusion. The majority of the patients presented a PI > 1.1 (76%). PI on the first day (but not the third day) could predict a positive CAM-ICU test in septic patients (PI cut-off: 1.3, AUC: 0.905, p < 0.01, sensitivity: 95%, specificity: 88%, AUC: 0.618, p = 0.24). Multivariable analysis showed that PI on the first day is related to a positive CAM-ICU test independent of age and APACHE II score (OR: 5.6, 95% CI: 1.1-29, p = 0.03). A decrease of the PI on the third day was observed in the group that presented initially high PI (>1.3) (2.2 ± 0.71 vs. 1.81 ± 0.64; p = 0.02). On the other hand, an increase in PI was observed in the other patients (1.01 ± 0.15 vs. 1.58 ± 0.57; p < 0.01). On only the first day, the mean blood velocity in the middle cerebral artery and CBFi were found to be lower in those patients with a high initial PI (36 ± 21 vs. 62 ± 28 cm/sec; p < 0.01, 328 ± 101 vs. 581 ± 108; p < 0.01, respectively).

Conclusions

Cerebral perfusion disturbance observed with Transcranial Doppler could explain clinical symptoms of sepsis-associated encephalopathy.

Intracranial atherosclerotic disease

Atherosclerotic disease of the intracranial arteries is responsible for at least 10% of ischaemic strokes worldwide. Symptomatic disease has been extensively studied in the past few years, using diagnostic methods including multi-slice computed tomography and high resolution magnetic resonance imaging. A literature search was performed using PubMed and OvidSP between 1984 and May 2013. Variations of the terms 'intracranial atherosclerosis' plus 'ischemic stroke', 'plaque', 'morphology', 'imaging' were used and a combination of them. The reference lists of identified articles were also consulted for additional references. Amongst symptomatic patients the prevalence of intracranial atherosclerotic disease is around 10%, depending on race ethnicity, and the diagnosis requires the presence of ≥50% stenosis in the territory of the symptomatic vessel in a patient with stroke or transient ischaemic attack. The prognosis of intracranial atherosclerotic disease related stroke is poor. Although risk factor control can lead to a better outcome of intracranial atherosclerotic disease related strokes, the significance of asymptomatic disease is still a matter of debate.

Imaging and clinical predictors of unfavorable outcome in medically treated symptomatic intracranial atherosclerotic disease

BACKGROUND

Patients with symptomatic intracranial atherosclerotic disease (sICAD) have an increased risk of stroke and vascular death. The aim of the study was to evaluate the natural history and outcome of patients with sICAD treated medically.

METHODS

The study population was first-ever transient ischemic attack (TIA) or stroke patients presenting to our institute who on vascular imaging had isolated intracranial atherosclerosis as cause of their symptoms and have a follow-up of 90 days. Unfavorable outcome was defined as occurrence of TIA, stroke, acute coronary event, and/or vascular death.

RESULTS

Fifty-three (11.8%) of the 449 ischemic stroke patients had sICAD. The risk of stroke in sICAD was 8.9%, 11.1%, 13.3%, and 15.6% in first 7 days, 30 days, 90 days, and 1 year, respectively. Five (11.1%) had cardiovascular events and accounted for 50% of mortality. The predictors of unfavorable outcome were presented as limb weakness (85.7% versus 58.8%, hazard ratio 1.5; 95% confidence interval [CI], .05-.9; P = .04), National Institutes of Health Stroke Scale (NIHSS) score 8 at admission (50% versus 5.9%, hazard ratio 8.5; 95% CI, .007-.5; P = .02), magnetic resonance imaging (MRI) with multiple diffusion-weighted imaging (DWI) lesions (65.4% versus 26.7%; 95% CI, .04-.7; P = .01), and angiography suggestive of diffuse atherosclerosis (50% versus 11.8%; 95% CI, odds ratio .02-.7; P = .009). On stepwise multiple regression, variables for unfavorable outcome were NIHSS score of 8 or more at admission (P = .001), multiple DWI lesion on MRI (P = .04), and diffuse atherosclerosis on angiography (P = .006).

CONCLUSION

The patients with sICAD have a high risk of stroke and cardiac events even on aggressive medical treatment. Clinical and imaging features can identify this high-risk group.

Color Doppler of the extracranial and intracranial arteries in the acute phase of cerebral ischemia

Vascular imaging greatly improves the possibility of locating the site of vascular occlusion in patients with acute cerebrovascular disease. Different occlusive patterns may underlie the same clinical presentation, with different prognosis and different treatment: for this reason, a diagnostic tool able to identify quickly the status of the extra- and intracranial vessels is needed. Color Doppler ultrasound of the extracranial arteries is a reliable and accurate method able to localize and quantify the carotid artery stenosis. The ultrasound quantification of the degree of stenosis is based on both morphological and velocimetric criteria: B-mode, color or power Doppler and spectral analysis are used for this purpose. Also the analysis of the plaque is an integral part of the ultrasound examination: the B mode plaque characterization (structure and surface) plays an important role in the evaluation of risk of stroke. So color Doppler ultrasound is able to select patients who may require medical therapy, carotid endarterectomy or angioplasty and stenting. Transcranial color Doppler is an inexpensive, reliable, fast, non-invasive, bedside tool: in the acute phase of stroke, it is able to evaluate quickly the intracranial arteries and monitor the possible recanalization of occluded vessel ensuring the follow-up of dynamic lesions, such as the intracranial stenosis and occlusions.

Transcranial doppler assessment of cerebral perfusion in critically ill septic patients: a pilot study

Background

The aim of this study is to evaluate the feasibility and efficacy of Transcranial Doppler (TCD) in assessing cerebral perfusion changes in septic patients.

Methods

Using TCD, we measured the mean velocity in the middle cerebral artery (VmMCA, cm/sec) and calculated the pulsatility index (PI), resistance index (RI) and cerebral blood flow index (CBFi = 10*MAP/1.47^PI) on the first day of patients’ admission or on the first day of sepsis development; measurements were repeated on the second day. Sepsis was defined according to standard criteria.

Results

Forty-one patients without any known neurologic deficit treated in our 24-bed Critical Care Unit were assessed (Sepsis Group = 20, Control Group = 21). Examination was feasible in 91% of septic and 85% of non-septic patients (p = 0.89). No difference was found between the two groups in mean age, mean arterial pressure (MAP) or APACHE II score. The pCO₂ values were higher in septic patients (46 ± 12 vs. 39 ± 4 mmHg p < 0.01). No statistically significant higher values of VmMCA were found in septic patients (110 ± 34 cm/sec vs. 99 ± 28 cm/sec p = 0.17). Higher values of PI and RI were found in septic patients (1.15 ± 0.25 vs. 0.98 ± 0.16 p < 0.01, 0.64 ± 0.08 vs. 0.59 ± 0.06 p < 0.01, respectively). No statistically significant lower values of CBFi were found in septic patients (497 ± 116 vs. 548 ± 110 p = 0.06).

Conclusions

Our results suggest cerebral vasoconstriction in septic compared to non-septic patients. TCD is an efficient and feasible exam to evaluate changes in cerebral perfusion during sepsis.

Effect of velocity profile skewing on blood velocity and volume flow waveforms derived from maximum Doppler spectral velocity

Given evidence that fully developed axisymmetric flow may be the exception rather than the rule, even in nominally straight arteries, maximum velocity (V(max)) can lie outside the Doppler sample volume (SV). The link between V(max) and derived quantities, such as volume flow (Q), may therefore be more complex than commonly thought. We performed idealized virtual Doppler ultrasound on data from image-based computational fluid dynamics (CFD) models of the normal human carotid artery and investigated how velocity profile skewing and choice of sample volume affected V(max) waveforms and derived Q variables, considering common assumptions about velocity profile shape (i.e., Poiseuille or Womersley). Severe velocity profile skewing caused substantial errors in V(max) waveforms when using a small, centered SV, although peak V(max) was reliably detected; errors with a long SV covering the vessel diameter were orientation dependent but lower overall. Cycle-averaged Q calculated from V(max) was typically within ±15%, although substantial skewing and use of a small SV caused 10%-25% underestimation. Peak Q derived from Womersley's theory was generally accurate to within ±10%. V(max) pulsatility and resistance indexes differed from Q-based values, although the Q-based resistance index could be predicted reliably. Skewing introduced significant error into V(max)-derived Q waveforms, particularly during mid-to-late systole. Our findings suggest that errors in the V(max) and Q waveforms related to velocity profile skewing and use of a small SV, or orientation-dependent errors for a long SV, could limit their use in wave analysis or for constructing characteristic or patient-specific flow boundary conditions for model studies.

Sonothrombolysis in ischemic stroke

OPINION STATEMENT

Acute ischemic stroke remains one of the most devastating diseases when it comes to morbidity and mortality, not to mention the personal and economic burden that occurs in long-term. Intravenous thrombolysis with tissue plasminogen activator (tPA) is the only effective acute stroke therapy that improves outcome if given up to 4.5 hours from symptom onset. However, recanalization rates are meager and the majority of treated patients still have residual disability after stroke, emphasizing the need for further treatment options that may facilitate or even rival the only approved therapy. Sonothrombolysis, the adjuvant continuous ultrasound sonication of an intra-arterial occlusive thrombus during thrombolysis, enhances the clot-dissolving capabilities of intravenous tPA presumably by delivering acoustic pressure to the target brain vessel. Higher recanalization rates produce a trend towards better functional outcomes that could be safely achieved with the combination of high-frequency ultrasound and intravenous tPA. However, data on ultrasound targeting of intracranial proximal occlusive lesions other than those in the middle cerebral arteries are sparse. Moreover, recent sonothrombolysis trials were exclusively conducted with operator-dependent hand-held technology hindering its further testing in clinical sonothrombolysis trials. An operator-independent 2-MHz transcranial Doppler device has been developed allowing health care professionals not formally trained in ultrasound apparatus to provide therapeutic ultrasound as needed. Currently, this operator-independent device covering 12 proximal intracranial segments that most commonly contain thrombo-embolic occlusions enters testing in a pivotal multicenter sonothrombolysis efficacy trial. If this trial demonstrates safety and efficacy, adjuvants, such as gaseous microbubbles that further potentiate the thrombolytic effect of intravenous tPA, could be tested along with this device.

Derivation of transcranial Doppler criteria for angiographically proven middle cerebral artery vasospasm after aneurysmal subarachnoid hemorrhage

BACKGROUND

Transcranial Doppler (TCD) has been subjected to criticism for detecting vasospasm (VSP). Our study's aim is to derive criteria for middle cerebral artery (MCA) vasospasm (MCA-VSP) based on cerebral angiography (CA).

METHODS

A prospective data of patients with aneurysmal subarachnoid hemorrhage (aSAH) from January 2004 to August 2009. TCD was performed daily from day 2 to 14 from symptom's onset. Follow-up CA was done at day 7-9. TCD mean flow velocities (MFV) of all vessels at baseline (b), middle (m) and before CA (preangio) were recorded. Several MCA MFV ratios were computed. Moderate to severe VSP on CA was defined as >1/3 luminal narrowing. Univariate and stepwise logistic regression analysis were performed.

RESULTS

One hundred sixty-nine patients (338 MCA) with aSAH were included, mean age: 54.8 ± 13, women: 103 (62%). Twenty-nine patients (8.6%) had angiographic MCA-VSP. TCD scoring system of 3 points for MCA-VSP was computed based on (a) bMCA MFV ≥ 120 cm/s (sensitivity: 59.3%, specificity: 85%, PPV: 36.4%, NPV: 93.5%, P < .001) (1 point), Preangio MCA MFV ≥ 150 cm/s (79.3%, 89.9%, 39%, 97.3%, <.001) (1 point), and affected preangio MCA/bMCA MFV ratio ≥ 1.5 (84%, 63%, 25.6%, 96.3%, .001) (1 point). The score of 3 has 96% sensitivity and 96% specificity (OR: 300) whereas the score of 1 has 12% sensitivity and 58% specificity (OR: 4.3) for identifying MCA-VSP.

CONCLUSION

TCD stringent criteria for moderate to severe MCA-VSP are feasible and applicable in aSAH population.

Reevaluating the transcranial Doppler criteria for estimation of anterior circulation artery stenosis: transcranial Doppler sonography versus digital subtraction angiography

OBJECTIVES

The criteria for evaluating cerebral artery stenosis by transcranial Doppler sonography are inconsistent. We aimed to identify the accuracy of transcranial Doppler criteria compared with digital subtraction angiography for diagnosis of anterior circulation artery stenosis.

METHODS

A total of 170 patients who underwent transcranial Doppler sonography and digital subtraction angiography were recruited. The anterior circulation arteries were evaluated by transcranial Doppler sonography and digital subtraction angiography. We defined the best cutoff value for substantial anterior circulation artery stenosis by receiver operating characteristic curve analyses and calculated the sensitivity, specificity, and positive and negative predictive values.

RESULTS

An anterior circulation artery peak systolic velocity (PSV) of 120 cm/s had the largest area under the receiver operating characteristic curve compared with PSVs of 110, 130, and 140 cm/s and mean flow velocities of 60, 70, and 80 cm/s. The sensitivity, specificity, false-positive rate, false-negative rate, accuracy, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, and Youden index for transcranial Doppler sonography were 90.6%, 85.0%, 15.0%, 9.4%, 87.9%, 87.2%, 88.9%, 6.04, 0.11, and 0.756, respectively. The reliability index included the agreement rate and κ value, which were 87.9% and 0.757.

CONCLUSIONS

A PSV of 120 cm/s combined with additional parameters was an accurate criterion for diagnosing anterior circulation artery stenosis. Transcranial Doppler sonography could be considered a valuable method for screening diagnosis of cerebral artery stenosis.

Prevalence of symptomatic intracranial atherosclerosis in Caucasians: a prospective, multicenter, transcranial Doppler study

BACKGROUND

There are limited data available regarding symptomatic intracranial atherosclerosis (SIA) prevalence in Caucasians. We sought to investigate SIA prevalence among Caucasian patients hospitalized with acute cerebral ischemia (ACI) in a prospective, multicenter Transcranial Doppler sonography (TCD) study.

METHODS

Consecutive patients with ACI were prospectively evaluated with TCD over a 24-month-period. The previously validated criteria of SONIA trial were used for detection of >50% intracranial stenosis with TCD. Brain angiography was performed to confirm the diagnosis in cases with abnormal TCD findings. SIA was diagnosed when there was evidence of a cerebral infarction in the territory of the stenotic artery (identified by TCD and confirmed by Magnetic resonance angiography [MRA]/Computed tomography angiography [CTA]).

RESULTS

A total of 467 consecutive patients with ACI (60.4% men, mean age 58 ± 14 years) were evaluated. SIA was documented in 43 patients (9.2%; 95%CI: 6.9%-12.2%). The most common SIA location was M1MCA (34.9%) followed by TICA (18.8%). Diabetes mellitus (OR: 4.25, 95%CI: 2.18-8.26; P < .001) and hypertension (OR: 2.41, 95%CI: 1.02-5.67; P = .045) were independently associated with SIA on multivariate models adjusting for potential confounders.

CONCLUSIONS

SIA was identified in almost 10% of patients admitted with symptoms of ACI. These preliminary findings support further collaborative initiatives among stroke physicians to increase the yield of SIA detection in Caucasian patients with ACI.

The prognostic value of pulsatility index, flow velocity, and their ratio, measured with TCD ultrasound, in patients with a recent TIA or ischemic stroke

BACKGROUND - Increased flow velocities, and combinations of low mean flow velocity (MFV) and a high pulsatility index (PI) are associated with intracranial arterial disease. We investigated the association of MFV and the ratio of PI and MFV (PI-MFV ratio) in the middle cerebral artery (MCA) with recurrence of vascular events in patients with a transient ischemic attack (TIA) or minor ischemic stroke. METHODS - Five hundred and ninety-eight consecutive patients underwent TCD investigation. Outcome events were fatal or non-fatal stroke and the composite of stroke, myocardial infarction, or vascular death (major vascular events). Hazard ratios (HR) were estimated with Cox proportional hazards multiple regression method, adjusted for age, gender, and vascular risk factors. RESULTS - TCD registration was successful in 489 patients. Mean follow-up was 2.1 years. Cumulative incidence was 9% for all stroke and 12% for major vascular events. MFV over 60.5 cm/s increased the risk for both stroke (HR 2.8; 95% CI: 1.3-6.0) and major vascular events (HR 2.6; 95% CI: 1.3-5.0). Each unit increase in PI-MFV ratio was associated with a HR 2.8 (95% CI: 1.7-4.8) for stroke and HR 2.2 (95% CI: 1.3-3.6) for major vascular events. CONCLUSION - In patients with a TIA or non-disabling ischemic stroke, MFV and the PI-MFV ratio in the MCA are independent prognostic factors for recurrent vascular events.

Velocity criteria for intracranial stenosis revisited: an international multicenter study of transcranial Doppler and digital subtraction angiography

BACKGROUND AND PURPOSE

Intracranial atherosclerotic disease is associated with a high risk of stroke recurrence. We aimed to determine accuracy of transcranial Doppler screening at laboratories that share the same standardized scanning protocol.

METHODS

Patients with symptoms of cerebral ischemia were prospectively studied. Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SONIA) criteria were used for identification of ≥50% stenosis. We determined velocity cutoffs for ≥70% stenosis on digital subtraction angiography by Warfarin-Aspirin Symptomatic Intracranial Disease criteria and evaluated novel stenotic/prestenotic ratio and low-velocity criteria.

RESULTS

A total of 102 patients with intracranial atherosclerotic disease (age 57±13 years; 72% men; median National Institutes of Health Stroke Scale 3, interquartile range 6) provided 690 transcranial Doppler/digital subtraction angiography vessel pairs. On digital subtraction angiography, ≥50% stenosis was found in 97 and ≥70% stenosis in 62 arteries. Predictive values for transcranial Doppler SONIA criteria were similar (P>0.9) between middle cerebral artery (sensitivity 78%, specificity 93%, positive predictive value 73%, negative predictive value 94%, and overall accuracy 90%) and vertebral artery/basilar artery (69%, 98%, 88%, 93%, and 92%). As a single velocity criterion, most sensitive mean flow velocity thresholds for ≥70% stenosis were: middle cerebral artery>120 cm/s (71%) and vertebral artery/basilar artery>110 cm/s (55%). Optimal combined criteria for ≥70% stenosis were: middle cerebral artery>120 cm/s, or stenotic/prestenotic ratio≥3, or low velocity (sensitivity 91%, specificity 80%, receiver operating characteristic 0.858), and vertebral artery/basilar artery>110 cm/s or stenotic/prestenotic ratio≥3 (60%, 95%, 0.769, respectively).

CONCLUSIONS

At laboratories with a standardized scanning protocol, SONIA mean flow velocity criteria remain reliably predictive of ≥50% stenosis. Novel velocity/ratio criteria for ≥70% stenosis increased sensitivity and showed good agreement with invasive angiography.

Validation of transcranial Doppler with magnetic resonance angiography in acute cerebral ischemia

BACKGROUND AND PURPOSE

Transcranial Doppler (TCD) is often used as a screening tool for detecting intracranial stenosis. Since TCD results may vary among laboratories and sonographers, it requires validation against an imaging modality. We evaluated diagnostic accuracy of TCD performed in our laboratory against time-of-flight (TOF) magnetic resonance angiography (MRA) in detecting intracranial stenosis in patients with acute cerebral ischemia.

METHODS

Consecutive patients with acute (<24 hours) cerebral ischemia and intracranial arterial stenosis on MRA underwent both TCD and MRA within 5 hours of each other. TCD was performed by credentialed neurosonologists according to standardized protocol. An independent neuroradiologist interpreting MRA was blinded to TCD findings. We evaluated TCD peak systolic velocities (PSV) in proximal intracranial arteries as predictive of moderate (>50%) and severe (>70%) stenosis on TOF-MRA.

RESULTS

One hundred and fifty patients (74% males; mean age 53 years) underwent neurovascular evaluation with TCD and MRA. Twenty-two (14.6%) patients were excluded due to absent temporal acoustic windows. Middle cerebral artery TCD PSV values of >140 cm/s and >180 cm/s were found to predict a >50% and >70% focal stenosis, respectively. Optimal cut-off PSV values for other major proximal intracranial arteries were also established.

CONCLUSIONS

TCD performed in our laboratory shows satisfactory agreement with TOF-MRA in diagnosis and grading of proximal intracranial stenosis in patients with acute cerebral ischemia.