Hyperacute Arterial Stroke II - Clinical Case Summary
Hyperacute Arterial Stroke II - Clinical Case Summary
Hyperacute Arterial Stroke II - Clinical Case Summary
SummaryHistory
51 year old female presenting with an acute left facial droop, left side weakness, and mental status change. Patient was able to be seen in the ER within 1 to 1.5 hours after the onset of symptoms.
Exams Performed
CT Head; CT Perfusion; CTA Neck; CTA Head;
CTA Venocapillary Pool; MR Diffusion; MR Flair; MR Susceptibility
Prior Available Reports
CT head
1. Abnormal right high cervical ICA consistent with dissection
CTA final impression
1. Rt. high cervical ICA dissection w/ limited antegrade blood flow beyond the 70% luminal stenosis The combination of antegrade flow plus pial collaterals revealed on cortical pial collateral gap.
2. Subtle reduction in the CT density within the venocapillary pool in the Rt. suprasylvian subcortical parietal white matter, likely representing end-of the-line ischemia in a posteriorly shifted watershed zone to the parietal white matter and the MCA-PCA watershed region. MR would be of value in determining whether there is actual acute post ischemic tissue in the region of the brain.
3. There is minimal post-ischemic dysautoregulation in the right superior division MCA.
4. Features of FMD in the left high ICA making FMD the likely the basis for the spontaneous right ICA dissection.
MR diffusion: DWI/ADC maps
1. Positive sites of diffusion were evident in the right mesial globus pallidus and in the right centrum semiovale mainly in the frontoparietal and parietal areas sparing the frontal and orbitofrontal white matter. These sites correspond to the mesial lenticulostriate and posterior part of the ACA-MCA watershed zones.
MR flair
1. Known acute Rt. high cervical ICA dissection with limited antegrade blood flow beyond the 70% stenosis.
2. Positive diffusion for stroke in Rt. parietal MCA-PCA component of a posteriorly shifted watershed zone. There are likely two components of the stroke based on the difference in FLAIR conspicuity; the rostral part is likely acute and the caudal part is likely hyperacute. FLAIR is also positive in the mesial globus pallidus with the stroke age and or depth and duration similar to the more caudal part of the stroke in the centrum semiovale.
3. Positive early FLAIR signal in a hyperacute mesial lenticulostriate perforator branch.
4. No hemorrhagic transformation nor venous egress obstruction is evident.
MR susceptibility
1. The SWI sequence was not performed. However, the included GRE exam demonstrated no susceptibility artifact related to arterial occlusion, nor venous stasis, nor hemorrhagic conversion.
1. Abnormal right high cervical ICA consistent with dissection
CTA final impression
1. Rt. high cervical ICA dissection w/ limited antegrade blood flow beyond the 70% luminal stenosis The combination of antegrade flow plus pial collaterals revealed on cortical pial collateral gap.
2. Subtle reduction in the CT density within the venocapillary pool in the Rt. suprasylvian subcortical parietal white matter, likely representing end-of the-line ischemia in a posteriorly shifted watershed zone to the parietal white matter and the MCA-PCA watershed region. MR would be of value in determining whether there is actual acute post ischemic tissue in the region of the brain.
3. There is minimal post-ischemic dysautoregulation in the right superior division MCA.
4. Features of FMD in the left high ICA making FMD the likely the basis for the spontaneous right ICA dissection.
MR diffusion: DWI/ADC maps
1. Positive sites of diffusion were evident in the right mesial globus pallidus and in the right centrum semiovale mainly in the frontoparietal and parietal areas sparing the frontal and orbitofrontal white matter. These sites correspond to the mesial lenticulostriate and posterior part of the ACA-MCA watershed zones.
MR flair
1. Known acute Rt. high cervical ICA dissection with limited antegrade blood flow beyond the 70% stenosis.
2. Positive diffusion for stroke in Rt. parietal MCA-PCA component of a posteriorly shifted watershed zone. There are likely two components of the stroke based on the difference in FLAIR conspicuity; the rostral part is likely acute and the caudal part is likely hyperacute. FLAIR is also positive in the mesial globus pallidus with the stroke age and or depth and duration similar to the more caudal part of the stroke in the centrum semiovale.
3. Positive early FLAIR signal in a hyperacute mesial lenticulostriate perforator branch.
4. No hemorrhagic transformation nor venous egress obstruction is evident.
MR susceptibility
1. The SWI sequence was not performed. However, the included GRE exam demonstrated no susceptibility artifact related to arterial occlusion, nor venous stasis, nor hemorrhagic conversion.
Overall impression
1. Acute dissection of the high cervical right ICA with a >70% luminal stenosis. There is reasonably good pial collateral to the brain in general.
2. Despite reasonable pial collateral there is evidence of acute ischemic tissue injury in the ACA-MCA watershed zone within the centrum semiovale. The cortex of the right cerebrum shows no evidence of post ischemic injury.
2. Despite reasonable pial collateral there is evidence of acute ischemic tissue injury in the ACA-MCA watershed zone within the centrum semiovale. The cortex of the right cerebrum shows no evidence of post ischemic injury.
Lessons to be learned
1. This case illustrates what happens to the collateralization pattern when a primary stem high-grade stenosis (or occlusion) is combined with an incomplete circle of Willis. In this case the posterior part of the circle of Willis is incomplete, while the anterior part is intact, which shifts the effective ACA-MCA watershed zone posteriorly. Thus, the ischemic injury is unexpectedly centered in the parietal centrum semiovale more than in the frontal or frontoparietal components. Notice how the cortical perfusion remains normal and diffusion, while the posteriorly shifted watershed zone suffers the ischemic injury.
2. Therefore, to understand stroke patterns, each imager must recognize how collateralization alterations shift depending on the state of the circle of Willis and the tandem sites of arterial high-grade stenosis or occluded distal arteries. It is not uncommon to the actual stroke-zone occur not within the expected end-of the-line in the pial collateral gap between antegrade flow versus retrograde pial collateral blood flow. Rather, as in this case, the stroke is not in the expected site of oligemia, occurs in the adjacent parietal centrum semiovale and in the MCA-PCA because of altered collateral pattern shifting the watershed site.
2. Therefore, to understand stroke patterns, each imager must recognize how collateralization alterations shift depending on the state of the circle of Willis and the tandem sites of arterial high-grade stenosis or occluded distal arteries. It is not uncommon to the actual stroke-zone occur not within the expected end-of the-line in the pial collateral gap between antegrade flow versus retrograde pial collateral blood flow. Rather, as in this case, the stroke is not in the expected site of oligemia, occurs in the adjacent parietal centrum semiovale and in the MCA-PCA because of altered collateral pattern shifting the watershed site.
Recommendations
Watch the included summary video for this instructional case.