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Case Notes
History
50 year old female presenting with acute-onset, left-sided, weakness.Exam
CTA of the Head
This part of the stroke protocol CTA is performed after the 1st bolus of contrast and is referred to as the initial post contrast head CTA exam. Since there is no recirculation of contrast, it has the advantage of identifying stenoses and short segment occlusions without obscuration by pial collateral. On the other hand, it may underfilling patent, more distal, arteries, which, of course, also reduces the CT-density in the venocapillary pool within brain parenchyma. Thus, the initial post contrast head CTA tends to overestimate the depth of injury in the apparent stroke-zone.
Purpose
1. To define sites of afferent supratentorial arterial thrombosis or flow-limiting high-grade stenosis or lesser but tandem stenoses, or stenosis plus incomplete circle of Willis with isolated arterial circuit;
2. To define sites of afferent infratentorial arterial thrombosis or flow-limiting high-grade stenosis;
3. To determine features of vessel wall and intimal status;
4. To assess presence of tandem stenosis or stenosis plus incompetent circle of Willis;
5. In case of ICA stenosis/occlusion is there effective EC-IC collateral;
6. Is there a watershed stroke zone affecting the usual anastomotic arterial boundary zones;
7. in case of afferent arterial block, plus an incomplete circle of Willis, is there a potential end-of the-line type of watershed stroke;
8. To assess status of retrograde pial collateral and asses for any pial collateral gap between proximal thrombus & retrograde pial collateral;
9. To assess for delayed venous egress (need to prove on post contrast CT head whether it is just delayed or is actually persistently reduced or absent).
This part of the stroke protocol CTA is performed after the 1st bolus of contrast and is referred to as the initial post contrast head CTA exam. Since there is no recirculation of contrast, it has the advantage of identifying stenoses and short segment occlusions without obscuration by pial collateral. On the other hand, it may underfilling patent, more distal, arteries, which, of course, also reduces the CT-density in the venocapillary pool within brain parenchyma. Thus, the initial post contrast head CTA tends to overestimate the depth of injury in the apparent stroke-zone.
Purpose
1. To define sites of afferent supratentorial arterial thrombosis or flow-limiting high-grade stenosis or lesser but tandem stenoses, or stenosis plus incomplete circle of Willis with isolated arterial circuit;
2. To define sites of afferent infratentorial arterial thrombosis or flow-limiting high-grade stenosis;
3. To determine features of vessel wall and intimal status;
4. To assess presence of tandem stenosis or stenosis plus incompetent circle of Willis;
5. In case of ICA stenosis/occlusion is there effective EC-IC collateral;
6. Is there a watershed stroke zone affecting the usual anastomotic arterial boundary zones;
7. in case of afferent arterial block, plus an incomplete circle of Willis, is there a potential end-of the-line type of watershed stroke;
8. To assess status of retrograde pial collateral and asses for any pial collateral gap between proximal thrombus & retrograde pial collateral;
9. To assess for delayed venous egress (need to prove on post contrast CT head whether it is just delayed or is actually persistently reduced or absent).
Prior Study
Noncontrast Head CTDense mural calcification in Rt. ICA which projects over the arterial lumen; this could represent a site of high cervical Rt ICA flow-limiting stenosis.
No clear evidence of acute stroke is evident.
CT Perfusion
Reduced perfusion rate in the Rt. MCA territory, but the area appears physiologically compensated by collateral blood flow.
CTA of the Neck
Rt. carotid bifurcation has moderate focal stenosis affecting both the EAC & IAC origins in the 50% range.
Rt. proximal ICA is occluded just after carotid sinus with apparent intraluminal soft clot consistent with hyperacute thrombus formation.
Rt. ICA reopacifies at mid-cavernous segment from ascending pharyngeal artery to infra-lateral trunk EC-IC connection. However, the reopacified ICA has less contrast density and is smaller in size than expected indicating less the fully functional EC-IC collateralization which puts the Rt. hemisphere at risk for hypoperfusion.
