Practice recommendations for neurovascular ultrasound investigations of acute stroke patients in the setting of the COVID-19 pandemic: an expert consensus from the European Society of Neurosonology and Cerebral Hemodynamics

Background and purpose

Patients with acute ischemic stroke are at high‐risk for contracting COVID‐19 infection. Additionally, healthcare professionals including neurovascular ultrasound providers are also at risk of being infected by SARS‐CoV‐2 virus. Yet, preparedness to continue to guarantee hyperacute treatment is vital for patients outcome. In light of this situation, the European Society of Neurosonology and Cerebral Hemodynamic (ESNCH) appointed a task force to provide consensus recommendations for the performance of neurovascular ultrasound investigations in acute ischemic stroke during the COVID‐19 pandemic with the aim of protecting both patients and ultrasound providers.

Methods

The “ultrasound in acute stroke working group” of the ESNCH examined literature articles and reviews using the following key words: “corona virus” or “COVID‐19” or “SARS‐CoV‐2 virus”, and “acute stroke” or “cerebrovascular disease”, and “ultrasound”. Thereafter, a thorough discussion was conducted with the “education and guidelines working group” of the ESNCH.

Results

We propose rapid up‐to‐date recommendations for healthcare personnel involved in the pre‐hospital and intra‐hospital assessment of stroke patients, with a particular attention to neurovascular ultrasound performance.

Conclusion

The ESNCH provides a guidance summary for the performance of neurovascular ultrasound investigations in acute ischemic stroke in the time of COVID‐19.

The Posterior Cerebral Artery and its Main Cortical Branches Identified with Noninvasive Transcranial Color-Coded Duplex Sonography

PURPOSE

To differentiate PCA segments and cortical branches by means of transcranial color-coded duplex sonography (TCCD) and to measure flow parameters at rest and during visual stimulation.

MATERIALS AND METHODS

60 healthy subjects with a good acoustic temporal bone window were examined. The main stem of the PCA (P1, P2 and P3) and 4 main cortical branches - the anterior temporal artery (ATA), the occipital temporal artery (OTA), the parietooccipital artery (POA) and the calcarine artery (CA) - were assessed using an axial transtemporal approach. Systolic and diastolic blood flow velocities (BFVs) were recorded at rest and during visual stimulation.

RESULTS

Identification of the P1 segment of the PCA was successful in 97.5% (117/120) of cases. The P2 and P3 segments were visualized in all cases. The 4 main cortical branches could be identified to varying degrees: ATA in 88%, OTA in 96%, POA in 69% and CA in 62%. There was an evoked flow response in the P2 main stem and in all cortical branches. The most pronounced increase in diastolic/systolic BFV after visual stimulation test was seen in the CA (42%/35%), followed by P2 (30%/24%), the POA (27%/27%), the OTA (16%/13%) and the ATA (9%/8%).

CONCLUSION

Insonation through the temporal bone window with TCCD confidently allows the assessment of the P1 to P3 segments of the PCA as well as the 2 proximal branches, the ATA and the OTA. An ultrasound-based classification of PCA anatomy and its cortical branches may be used as a noninvasive method for the evaluation of posterior circulation pathology.

Complete basilar artery assessment by transcranial color-coded duplex sonography using the combined transforaminal and transtemporal approach

PURPOSE

Visualization of the basilar artery (BA) by transcranial color-coded duplex sonography (TCCD) can be challenging. The detection of stenosis or occlusion of the BA often has to rely on indirect signs like a highly pulsatile flow in the vertebral arteries. In case of a distal BA occlusion, however, the flow of the VAs can even be normal. The aim of our TCCD study was to visualize a maximum length of the BA combining the customarily used transforaminal appraoch for the proximal part and the less well known transtemporal coronal approach for the distal BA segment.

MATERIALS AND METHODS

TCCD was performed in 60 subjects with a good temporal bone window. Detectable extracranial or intracranial pathology was previously excluded. The BA was insonated using the transforaminal and transtemporal insonation plane and the visible length was measured. In one subject MRA was performed to substantiate our findings.

RESULTS

The BA was visualized in all subjects via both approaches. The maximal detectable BA length via the transforaminal and transtemporal approach was 26 ± 8 mm and 18 ± 5 mm, respectively. Assuming a previously reported average anatomical total BA length of 33 ± 6 mm, we supposed complete vessel visualization in 44 subjects (73 %).

CONCLUSION

The combined transforaminal and transtemporal insonation approach may permit total BA insonation, thus facilitating the evaluation of BA pathology.

Superior cerebellar artery - a potential pitfall in transcranial posterior cerebral artery insonation

PURPOSE

Transcranial color-coded duplexsonography (TCCD) of the posterior cerebral artery (PCA) is commonly performed in an axial midbrain insonation plane. The proximal PCA is easily identified as a vessel, originating from the top of the basilar artery (BA). However, the initial segment of the superior cerebellar artery (SCA) also originates from the top segment of the BA and runs in parallel. Therefore, it is possible to confuse the two vessels. The aim of our study is to anatomically differentiate the proximal PCA and SCA by means of TCCD in the coronal plane using a transtemporal approach and to analyze and compare their flow responses during a visual stimulus paradigm.

MATERIALS AND METHODS

60 subjects without a relevant vascular pathology and with a good temporal bone window were examined. The distal BA, the proximal PCA and the SCA were insonated using a coronal insonation plane and identified by their anatomical relationship. The visible length was measured and the blood flow velocities were recorded at rest and during visual stimulation.

RESULTS

The identification and differentiation of both vessels was successful in 101 of 120 hemispheres (84.2 %). The PCA systolic flow velocities at rest and during visual stimulation were 58.4 +/- 11 and 71.8 +/- 13 cm/sec (23.6 % increase), while the SCA velocities were 50.7 +/- 12 and 53.5 +/- 13 cm/sec, respectively (5.8 % increase). The difference was significant (p < 0.001).

CONCLUSION

Using the coronal transtemporal insonation approach, TCCD makes it possible to identify and distinguish the proximal PCA and SCA. Our study is the first to provide a systematic ultrasound assessment of the SCA and includes data on normal flow velocities and reactivity to a visual stimulus.

Distinct reading of different structural determinants modulates the dileucine-mediated transport steps of the lysosomal membrane protein LIMPII and the insulin-sensitive glucose transporter GLUT4

Leucine-based motifs mediate the sorting of membrane proteins at such cellular sites as the trans-Golgi network, endosomes, and plasma membrane. A Leu paired with a second Leu, Ile, or Met, while itself lacking the ability to mediate transport, is the key structural feature in these motifs. Here we have studied the structural differences between the leucine-based motifs contained in the COOH tails of LIMPII and GLUT4, two membrane proteins that are transported through the secretory pathway and are targeted to lysosomes () and to a perinuclear compartment adjacent to the Golgi complex (), respectively. LIMPII and GLUT4 display negatively (Asp(470)/Glu(471)) and positively (Arg(484)/Arg(485)) charged residues, respectively, at positions -4 and -5 upstream from the critical Leu residue. The change in the charge sign of residues -4 and -5 results in missorting of LIMPII and GLUT4. We note that the acidic Glu residue at position -4 is critical for efficient intracellular sorting of LIMPII to lysosomes, but is dispensable for its surface internalization by endocytosis. Efficient intracellular sorting and endocytosis of GLUT4 require an Arg pair between positions -4 and -7. These results are consistent with the existence of distinct leucine-based motifs and provide evidence of their different readings at different cellular sites.

Transcranial Doppler Sonographic monitoring during percutaneous transluminal angioplasty of the internal carotid artery

Our purpose was to assess the haemodynamic changes in the ipsilateral middle cerebral artery (MCA) during and after percutaneous transluminal angioplasty (PTA) of the internal carotid artery (ICA), and to compare them with clinical and angiographic findings. Transcranial Doppler Sonographic monitoring (TCD) of the MCA was performed during PTA in 22 patients with symptomatic severe stenosis of the ICA. Mean blood flow velocity (MBFV) and pulsatility index (PI) were recorded. During PTA, MBFV fell from 41 +/- 15 cm/s to 23 +/- 11 cm/s (P = 0.0001). Changes in PI were inconsistent. With reduction of MBFV of 50% or less (in 10 cases) no complication occurred. With a reduction of more than 50% (in 12), 6 patients developed neurological disturbances (transient ischaemic attacks in 5 and minor stroke in 1). This difference was significant (P = 0.0152). Symptomatic patients also had a higher rate of stroke prior to PTA (4/6) than patients who remained asymptomatic during PTA (0/6). After PTA had been performed MBFV and PI improved significantly (P = 0.0001), MBFV increasing to 48 +/- 16 cm/s and PI from 0.64 +/- 0.11 to 0.86 +/- 0.15. TCD changes proved more sensitive to cerebral haemodynamics than angiography in 8 patients.

Simultaneous assessment of cerebral oxygenation and hemodynamics during a motor task. A combined near infrared and transcranial Doppler sonography study

During performance of a sequential finger opposition task we measured changes in regional cerebral blood oxygenation (rCBO) over the motor cortex and blood flow velocity changes (CBFV) in the middle cerebral artery in a combined near-infrared spectroscopy (NIRS) and transcranial Doppler Sonography (TCD) study. Stimulus duration was 60 followed by a 90 s rest period. During performance of the motor task we observed an increase in [oxy-Hb] a decrease in [deoxy-Hb] and an increase in MCA flow velocity. These changes were significantly more pronounced contralaterally than ipsilaterally to the moving hand. The time course of changes in [oxy-Hb] and CBFV were strikingly similar, showing a pronounced initial over-shoot. This study proves the feasibility of a simultaneous assessment of microcirculatory hemodynamics and cerebral oxygenation at high temporal resolution.