54 yo female with an acute left hemiparesis.

CT Head; CT Perfusion; CTA of the Neck; CTA of the head; Post contrast CT head; T1-w MR pre contrast only; MR diffusion; MR T2-w sequence; MR susceptibility (SWI)

CT Head
1. Nonhemorrhagic, hyperacute right MCA, superior division, ischemic event.

CT Perfusion
1. Evidence of a dense ischemic infarction in the right MCA, superior division, perfusion zone and in the right frontopolar ACA perfusion zone and in the right basal ganglia lenticulostriate perfusion zone.
2. Evidence of a moyamoya (adult) variant affecting the left A1 and M1 segments producing rapid right lenticulostriate perforator blood flow.
3. Extensive PCA related pial collateralization is evident bilaterally, but it is clearly effective on the left and into the inferior MCA divison on the right. The PCA and thalamoperforator collateral is clearly functional (effective tissue perfusion) in both thalami and in the left cerebrum. It is likely that the combination of choroidal ICA segment stenoses and the left lenticulostriate moyamoya perforator vasculopathy (causing a vascular "steal effect") have combined to result in a transcapillary stroke in the right cerebrum.

CTA of the neck
1. The cervial arteries are not significantly abnormal to affect intracranial circulation.
2. There is evidence of a combination of findings indicating the presence of an adult variant of moyamoya syndrome. The lenticulostriate moyamoya vasculopathy is only on the left and this is occuring in an adult patient.

CTA of the head
1. There is CTA evidence of the adult form of moyamoya syndrome exhibiting bilateral, high grade, choroidal ICA segment stenoses, moyamoya vasculopathy only on the left and evidence of left ethmoid meningeal-pial anastomoses. There are both prominent PCA pial collaterals, and the thalamoperforating collaterals, which appear to preserve parenchymal perfusion in the thalami bilaterally, in all of the left cerebrum and the inferior right MCA territory. The moyamoya vasculopathy maintains flow to the left basal ganglia.
2. There are tandem stenoses afffecting the right ICA with a flow-limiting extradural, subclinoidal atherosclerotic stenosis and an intradural. flow-limiting, moyamoya clinoidal ICA segment stenosis. These combine along with the hypoplastic A-com and the steal effect of the prominent left lenticulostriate moyamoya vasculopathy to significantly reduce blood flow to the superior division of the right MCA, despite the retrograde PCA pial collateral.
3. There is CTA evidence of opacification of the  patent proximal secondary stem branches on the right ICA and some distal MCA pial filling. However, this pial circulation is ineffective and there is NO evidence of parenchymal contrast density in affected right superior division MCA perfusion zone, nor in the right basal ganglia. This indicates that the level of arterial obstruction is at the metarteriole/capillary level (i.e "transcapillary type of stroke"). 

Post contrast CT head
1. There is virtually no rise in the CT density within the venocapillary pool in the distribution of the right MCA superior division consistent with dense ischemic core. There is a partial rise, but not to normal in the right basal ganglia and the right frontopolar region.
2. The venocapillary pool CT density is near normal in the left cerebrum.

Noncontrast T1-w sequence
1. Post ischemic cytogenic edema is evident in the right superior division of the MCA and in the rostral aspect of the right ACA, as well  as in the right basal ganglia.
2. There is slow flow in patent pial branches of the superior division right MCA and slow flow in the proximal right MCA stem segments from circle of Willis collateral that show up on the T1-w sequence that were not as well seen on the head CTA. Thus, pial collateral is reduced, but is at least present on the right. However, it is clear that the extent of pial blood supply does not translate to adequate transcapillary blood flow to avoid initiating the ischemic cascade. 
3. There is substantial cytogenic edema sufficient to produce a right to left subfalcine shift of roughly 3-4 mms.

MR diffusion
1. Acute, nonhemorrhagic, right superior division MCA, right frontal ACA, plus both the right A1/2 and  M1/2 perforator zone basal ganglia infarctions, estimated stroke age is consistent with 3-5 days of age.

MR T2-2 turbo spin-echo sequence
1. Recent, nonhemorrhagic, right, MCA/ACA transcapillary type of stroke with estimated stroke age of 3-5 days.
There is moderate focal cytogenic producing a4-5 mm midline shift and early optic hydrops (raised intracranial pressure)

MR susceptibility (SWI)
1. Acute right ACA/MCA infarction. The lack of pial and deep white matter venous filling and early parenchymal SWI change is consistent with a dense ischemic core involving all of the affected right cerebral oligemic zone. This is indicative of a completed arterial infarction.

1. Adult type of Moya-moya vasculopathy evident on the left with high grade ICA stenosis in the choroidal segment and the "puff of smoke" exaggerated lenticulostriate vessels. On the right there is a focal vascular stenosis in the subclinoidal ICA segment occluding the right ICA; distal right ICA vessels do fill from retrograde collateral. The right moya-moya vasculopathy does not fill from the retrograde collateral. 

2. Despite evidence of a proximal right ICA occlusion with retrograde collateral, the right MCA perfusion zone demonstrates a completed infarction mainly affect the right orbitofrontal artery of frontal superior division MCA perfusion zones. There is no hemorrhage.

1. The adult form of moyamoya vasculopathy differs from the childhood form in some ways beside occuring in adults. The adult form is often unilateral, and, the lenticulostriate vessels make less of a puff of smoke within the basal ganglia and tend to lineup along the arterial wall, as if they are mural collaterals by-passing a focal stenosis. It has some similar features including:  1. bilateral high-grade stenoses of the choroidal segment of the ICA (occuring just after the P-com and anterior choroidal artery take-offs), 2. peculiar enlargement of the A1/2 and M1/2 perforators to the basal ganglia (always) and the thalami (less often), 3. peculiar collateral connections between meningeal and intraaxial pial arteries. All the features are present bilaterally in the childhood form. The secondary form often is asymmetric between sides and may have other features of the underlying disorders (sickle cell dz and NF1). In this case, the patient is 54 years (obviously not a child), and the lenticulostriate collateral is more evident on the left and seems to concentrate along the MCA mural wall. It does have symmetric choroidal segment ICA stenoses. Moyamoya vasculopathy is a cause of stroke in all its' forms.

2. The CT perfusion in moyamoya disorders are confusing, but even more so when there is moyamoya leading to parenchymal arterial stroke(s). This case again points out the how the post contrast CT head can define the sites of true oligemia and distinguish them from effectively collateralized brain. The post contrast head CT provides only a rough estimate of parenchymal venous egress.

3. The MR susceptibility (SWI) provides the best evaluation of parenchymal venous egress. In this case neither the pial or the subcortical veins are evident in the site of the arterial stroke. Absence of venous filling is a feature of a dense ischemic core and completed stroke. The lack of blooming artifact in the deep medullary veins and deep central veins indicates that as least, for now, the infarction has not reached the level of medullary vein collapse with sequestered infarct.

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