Usefulness of Transcranial Doppler Ultrasound in Evaluating Cervical-Cranial Collateral Circulations

Abstract

Transcranial Doppler (TCD) ultrasound is a noninvasive, safe and cost-effective bedside test for evaluating cerebrovascular circulation in real time. It has been rapidly evolving from a simple noninvasive diagnostic tool to an imaging model with a broad spectrum of clinical applications. TCD can show the spectral flow waveforms, blood flow direction, velocities and intensity in the intracerebral vessels, adding physiologic information to other imaging models. TCD can also detect collateral channels through the anterior communicating artery, posterior communicating arteries, reversed ophthalmic artery, leptomeningeal collaterals, reversed basilar artery and reversed vertebral artery caused by hemodynamically significant carotid or intracranial stenosis. This article gives a brief overview of its use in evaluation of collateral circulation in carotid and intracranial steno-occlusive disease.

Transcranial Doppler and Transcranial Color Duplex in Defining Collateral Cerebral Blood Flow

“…Four types of CF can be defined on TCD and TCCD: primary CF, secondary CF, extracranial source of CF, and other types of collateral blood flow …”

“…In addition, especially when very small, it may not be functional in many individuals with normal cerebral circulation. Interestingly, in the presence of critical ICA stenosis or occlusion, there is an increase in the flow of blood through the AcomA as it becomes the collateral route of blood supply to the ipsilateral MCA and ACA making it easier to insonate . In addition, AcomA can be defined on power M mode TCD through the temporal window as a stenosis signal at midline at depth of 70–75 mm or at a depth of 60–65 mm through the orbital window (Figs A and B).…”

“…TCD may be helpful in the bedside evaluation of LMCs in acute stroke. Whereas LMCs cannot be visualized directly on routine TCD, they can be evaluated indirectly by measuring changes in the diverted blood flow to the ipsilateral ACA and PCA that probably supply the LMCs . Kim et al studied the relation between FD into the ipsilateral ACA and PCA and PMC circulation in the presence of proximal MCA occlusion .…”

Giant pseudoaneurysm of the external carotid artery causing stroke: A case report

“…9 In our case, CTA clearly showed the proximal occlusion of the right internal carotid artery. 12 Treatment of this kind of carotid pathology may include antithrombotic therapy, surgery, or endovascular therapy. 11 Unfortunately, because of the inadequate temporal acoustic windows, we could not obtain a detailed assessment of the pathways through the communicating arteries.…”

Applications and development of permeability imaging in ischemic stroke (Review)

“…However, the results of TCD are susceptible to subjective influences and vary with the operator and are therefore not highly repeatable, because the blood flow is small in the collateral vessel and it is difficult to tell the value exactly. In addition, TCD is only able to evaluate Level I collaterals (30). DSA is the gold standard for evaluating Level II and Level III intracranial collaterals.…”