Transcranial color-coded duplex sonography of the middle cerebral artery: more than just the M1 segment

Transcranial Doppler during the first week after cardiac arrest and association with 6-month outcomes

Background

Early prediction of outcomes in comatose patients after out-of-hospital cardiac arrest is challenging. Prognostication tools include clinical examination, biomarkers, and neuroradiological and neurophysiological tests. We studied the association between transcranial Doppler (TCD) and the outcome.

Methods

This was a pre-defined sub-study of the prospective observational Norwegian Cardiorespiratory Arrest Study. Patients underwent standardized post-resuscitation care, including target temperature management (TTM) to 33°C for 24 h. TCD was performed at days 1, 3, and 5-7. The primary endpoint was cerebral performance category (CPC) at 6 months, dichotomized into good (CPC 1-2) and poor (CPC 3-5) outcomes. We used linear mixed modeling time-series analysis.

Results

Of 139 TCD-examined patients, 81 (58%) had good outcomes. Peak systolic velocity in the middle cerebral artery (PSV) was low during TTM (Day 1) and elevated after rewarming (Day 3). Thereafter, it continued to rise in patients with poor, but normalized in patients with good, outcomes. At days 5-7, PSV was 1.0 m/s (95% CI 0.9; 1.0) in patients with good outcomes and 1.3 m/s (95% CI 1.1; 1.4) in patients with poor outcomes (p < 0.001).

Conclusion

Elevated PSV at days 5-7 indicated poor outcomes. Our findings suggest that serial TCD examinations during the first week after cardiorespiratory arrest may improve our understanding of serious brain injury.

Association of Transcranial Direct Current Stimulation and Neurofeedback With Declarative Memory and Cerebral Arterial Flow in University Students: Protocol for a Double-blind Randomized Controlled Study

BACKGROUND

The performance of a task depends on ongoing brain activity, which can be influenced by attention, excitement, or motivation. Scientific studies have confirmed that mindfulness leads to better performance, health, and well-being. However, these cognitive efficiency modulating factors are nonspecific, can be difficult to control, and are not suitable to specifically facilitate neural processing.

OBJECTIVE

The aim of this study is to evaluate the effects of transcranial direct current stimulation associated with neurofeedback on declarative memory and cerebral blood flow in university students.

METHODS

In this study, we will use transcranial direct current stimulation, a low-cost physical resource that is easy to apply, has few adverse effects, and is associated with a neurofeedback resource. This, in turn, has been shown to be a training program capable of improving working memory function.

RESULTS

Participants will be recruited between July 2022 and December 2022. This study is expected to conclude in July 2023.

CONCLUSIONS

This study will provide preliminary results on the benefits of using the direct current neurostimulation and neurofeedback tools on the participants being analyzed.

TRIAL REGISTRATION

Brazilian Clinical Trials Registry RBR-7zs8b5; https://ensaiosclinicos.gov.br/rg/RBR-7zs8b5.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/36294.

Evaluation of neurosonology versus digital subtraction angiography in acute stroke patients

Stroke is one of the most common neurological disorders with a high incidence in Middle-eastern regions. We aimed to assess the diagnostic accuracy of neurovascular ultrasound to detect of cerebral artery stenosis compared to digital subtraction angiography (DSA) as a gold standard method. Eighty patients presenting with symptoms of cerebral ischemia were enrolled in the study. They were examined by cervical color Doppler ultrasound and TCCS to determine stenosis of extracranial and intracranial arteries, respectively. DSA was performed 24-48 h after the initial examination. The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of neurovascular ultrasound in comparison to DSA were calculated. The agreement between the two methods was determined by kappa statistics. Eighty patients (60% male, 40% female) with a mean age of 61.32 ± 12.6 years were included. In 65% of patients, stenosis in carotid artery caused ischemic symptoms. We did not observe any stenosis in anterior cerebral artery, posterior cerebral artery and basilar artery in patients. The agreement between the neurovascular ultrasound and DSA in various arterial vessels was 0.9 for common carotid artery, 0.86 for internal carotid artery, 0.78 for middle cerebral artery, and 0.86 for vertebral artery. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and kappa value of the neurovascular ultrasound for detecting stenosis regarding the arterial segments were 84.8%, 81%, 92.6%, 65.4%, 83.8, and 0.71, respectively. In conclusion, the neurovascular ultrasound is a valuable, non-invasive, and repeatable method to investigate cerebral artery stenosis with high diagnostic accuracy.

Classification of Intracranial Stenoses: Discrepancies between Transcranial Duplex Sonography and Computed Tomography Angiography

Transcranial color-coded duplex sonography (TCCS) and computed tomography angiography (CTA) are widely used to identify intracranial stenoses (ISs). We assessed concordance of IS grading between TCCS and CTA and proposed new TCCS criteria for severe IS ≥70%. One hundred two stroke patients (70 ± 13 y) with TCCS-identified IS were included. TCCS and CTA were performed within 24 h after admission. TCCS peak systolic velocity cutoffs for <50%/50%-69% stenoses were ≥155/≥220 cm/s (middle cerebral artery [MCA]-M1), ≥100/≥140 cm/s (MCA-M2), ≥120/≥155 cm/s (anterior cerebral artery [ACA]-A1), ≥100/≥145 cm/s (posterior cerebral artery [PCA]-P1 and PCA-P2), ≥90/≥120 cm/s (vertebral artery [VA]-V4) and ≥100/≥140 cm/s (basilar artery [BA]). Criteria for ≥70% stenoses were, despite variable flow velocities, post-stenotic flow alterations and/or leptomeningeal collateral flow. One hundred seventy-seven ISs were detected by TCCS. The number and grade (<50%/50%-69%/≥70%) of ISs were MCA 70 (39/19/12), BA 24 (9/11/4), ACA 21 (14/7/0), PCA 49 (29/15/5) and VA 13 (2/6/5). IS localization was confirmed by CTA in 84 of 177 cases (48%): MCA, 41/70 (59%); BA, 16/24 (67%); ACA 2/21, (10%); PCA, 17/49 (35%); VA, 8/13 (62%). Concordance between TCCS and CTA grading was (<50%/50%-69%/≥70%) 17%/19%/77%. TCCS and CTA exhibited substantial differences in the detection and grading of IS. Higher concordance rates for severe stenosis support our proposed TCCS criteria.

Imaging transcranial Doppler ultrasound to measure middle cerebral artery blood flow: the importance of measuring vessel diameter

Cerebral blood flow (CBF) is commonly inferred from blood velocity measurements in the middle cerebral artery (MCA), using nonimaging, transcranial Doppler ultrasound (TCD). However, both blood velocity and vessel diameter are critical components required to accurately determine blood flow, and there is mounting evidence that the MCA is vasoactive. Therefore, the aim of this study was to employ imaging TCD (ITCD), utilizing color flow images and pulse wave velocity, as a novel approach to measure both MCA diameter and blood velocity to accurately quantify changes in MCA blood flow. ITCD was performed at rest in 13 healthy participants (7 men/6 women; 28 ± 5 yr) with pharmaceutically induced vasodilation [nitroglycerin (NTG), 0.8 mg] and without (CON). Measurements were taken for 2 min before and for 5 min following NTG or sham delivery (CON). There was more than a fivefold, significant, fall in MCA blood velocity in response to NTG (∆-4.95 ± 4.6 cm/s) compared to negligible fluctuation in CON (∆-0.88 ± 4.7 cm/s) (P < 0.001). MCA diameter increased significantly in response to NTG (∆0.09 ± 0.04 cm) compared with the basal variation in CON (∆0.00 ± 0.04 cm) (P = 0.018). Interestingly, the product of the NTG-induced fall in MCA blood velocity and increase in diameter was a significant increase in MCA blood flow following NTG (∆144 ± 159 ml/min) compared with CON (∆-5 ± 130 ml/min) (P = 0.005). These juxtaposed findings highlight the importance of measuring both MCA blood velocity and diameter when assessing CBF and document ITCD as a novel approach to achieve this goal.

Stenosis in Middle Cerebral Artery Duplication: Assessment With Transcranial Color-Coded Duplex Sonography

Duplication of the middle cerebral artery is an unusual anatomic variant. Stenosis of one of its branches can be an exceptional cause of stroke and is very difficult to diagnose with transcranial duplex sonography. We report 2 patients with duplication of the middle cerebral artery in whom stenosis of one of its branches led to ischemic stroke and describe the sonographic findings in comparison to other neuroimaging modalities. These cases highlight the utility of adding a coronal insonation plane on top of the traditional axial plane to avoid identification pitfalls in patients with anatomic variants.