Hyperacute Arterial Stroke VI - Clinical Case Summary
Hyperacute Arterial Stroke VI - Clinical Case Summary
Hyperacute Arterial Stroke VI - Clinical Case Summary
SummaryHistory
71 year old male presenting with acute onset slurred or muffled speech, no weakness, was able to understand speech, with no loss of consciousness.
Exams Performed
CT Head; CT Perfusion; CTA Neck; CTA Head; CTA Venocapillary Pool; MR Diffusion; MR Flair; MR Susceptibility
Prior available imaging reports
Noncontrast head CT
1. Hyperacute very focal intraluminal thrombus in a single mid insular M3 branch off the superior division Lt. MCA; stroke-age would likely be hyperacute.
CT perfusion
1. Focal area of minimally reduced CBV and CT density within the venocapillary pool in the mid left insula. This matches the territory of the acute branch thrombus on the noncontrast head CT.
2. The wider area of both prolonged TTP/MTT (compared to the CT) suggests that there is additional thrombus in the more proximal M3 trunk that is not currently hyperdense on CT.
CTA of the neck
1. Negative CTA of the neck for flow-limiting arterial or venous stenosis or occlusion.
CTA of the head
1. There is partial occlusion of the posterior trunk superior MCA division (non hyperdense) resulting in slower filling of arteries to the the posterior insula and distal M4 branches in the parietal and retrosylvian cortex. This matches the prolonged TTP/MTT and the hyperemic response to slow flow on the CT perfusion.
2. There is a single hyperdense artery to the central sulcus, which is hyperdense and does not fill in its’ initial segment. Retrograde pial collateral fills the distal part of this artery leaving a 1cm. area of pial collateral gap. This oligemic area includes the mid insula and adjacent intrasylvian cortex, which corresponds to the lower motor cortex including the tongue region, which in this patient has produced dysarthria.
3. Since CTA reveals a more proximal non hyperdense segment of thrombus in the posterior superior division trunk, it is possible that the hyperacute (hyperdense) single arterial thrombus may be the result of clot lysis and secondary embolization.
Post contrast head CT (venocapillary pool analysis)
1. Hyperacute thrombus affecting a single Lt. M3 (MCA) branch (i.e. the artery to the central sulcus). There is also an older partially occlusive thrombus (without CT-hyperdense thrombus) that involve the posterior M3 superior division trunk that is well collateralized but accounts for the wider zone of prolonged TTP on the CT perfusion. The rise of CT density in the venocapillary pool on the delayed CTA for most of the area of slow flow on the TTP (CT perfusion) indicates good collateralization.
2. The occlusion of the proximal part of the artery to the central sulcus produced a short pial collateral gap on the CTA which resolved on the delayed post constrast CTA. Despite reasonable pial collateral there was a small area of reduced CT density in the venocapillary pool in the mid-insula.The affected area does include the tongue primary motor areas accounting for the dysarthria symptom.
MR diffusion
1. Both the DWI & ADC maps are positive for a small stroke in the mid to posterior insula
MR flair
1. Very subtle edema is evident with the cortex of the insula deep to parietal lobe. Findings are consistent with hyperacute stroke timeframe.
MR susceptibility
1. SWI is positive for intraluminal thrombus in the posterior trunk of the M3 arteries. This indicates the proximal thrombus (which is not hyperdense) is likely older than the single more distal arterial hyperdense thrombus. Thus, it is likely that the early (probably silent) thrombus underwent clot lysis and secondary embolization to a symptom producing part of the cortex. This accounts for the inconsistency between the punctate hyperdensity on the noncontrast head CT and the wider zone of prolonged TTP on the CT perfusion sequence.
2. There is physiologic hyperemia in the collateral zone above actual stroke zone. This accounts for the venous prominence without any blooming artifact. It also matches the increase CBV on the CT perfusion.
1. Hyperacute very focal intraluminal thrombus in a single mid insular M3 branch off the superior division Lt. MCA; stroke-age would likely be hyperacute.
CT perfusion
1. Focal area of minimally reduced CBV and CT density within the venocapillary pool in the mid left insula. This matches the territory of the acute branch thrombus on the noncontrast head CT.
2. The wider area of both prolonged TTP/MTT (compared to the CT) suggests that there is additional thrombus in the more proximal M3 trunk that is not currently hyperdense on CT.
CTA of the neck
1. Negative CTA of the neck for flow-limiting arterial or venous stenosis or occlusion.
CTA of the head
1. There is partial occlusion of the posterior trunk superior MCA division (non hyperdense) resulting in slower filling of arteries to the the posterior insula and distal M4 branches in the parietal and retrosylvian cortex. This matches the prolonged TTP/MTT and the hyperemic response to slow flow on the CT perfusion.
2. There is a single hyperdense artery to the central sulcus, which is hyperdense and does not fill in its’ initial segment. Retrograde pial collateral fills the distal part of this artery leaving a 1cm. area of pial collateral gap. This oligemic area includes the mid insula and adjacent intrasylvian cortex, which corresponds to the lower motor cortex including the tongue region, which in this patient has produced dysarthria.
3. Since CTA reveals a more proximal non hyperdense segment of thrombus in the posterior superior division trunk, it is possible that the hyperacute (hyperdense) single arterial thrombus may be the result of clot lysis and secondary embolization.
Post contrast head CT (venocapillary pool analysis)
1. Hyperacute thrombus affecting a single Lt. M3 (MCA) branch (i.e. the artery to the central sulcus). There is also an older partially occlusive thrombus (without CT-hyperdense thrombus) that involve the posterior M3 superior division trunk that is well collateralized but accounts for the wider zone of prolonged TTP on the CT perfusion. The rise of CT density in the venocapillary pool on the delayed CTA for most of the area of slow flow on the TTP (CT perfusion) indicates good collateralization.
2. The occlusion of the proximal part of the artery to the central sulcus produced a short pial collateral gap on the CTA which resolved on the delayed post constrast CTA. Despite reasonable pial collateral there was a small area of reduced CT density in the venocapillary pool in the mid-insula.The affected area does include the tongue primary motor areas accounting for the dysarthria symptom.
MR diffusion
1. Both the DWI & ADC maps are positive for a small stroke in the mid to posterior insula
MR flair
1. Very subtle edema is evident with the cortex of the insula deep to parietal lobe. Findings are consistent with hyperacute stroke timeframe.
MR susceptibility
1. SWI is positive for intraluminal thrombus in the posterior trunk of the M3 arteries. This indicates the proximal thrombus (which is not hyperdense) is likely older than the single more distal arterial hyperdense thrombus. Thus, it is likely that the early (probably silent) thrombus underwent clot lysis and secondary embolization to a symptom producing part of the cortex. This accounts for the inconsistency between the punctate hyperdensity on the noncontrast head CT and the wider zone of prolonged TTP on the CT perfusion sequence.
2. There is physiologic hyperemia in the collateral zone above actual stroke zone. This accounts for the venous prominence without any blooming artifact. It also matches the increase CBV on the CT perfusion.
Overall impression
1. Acute (hyperdense thrombus on CT) intraluminal thrombus in the intrasylvian part of the right artery to the central sulcus (i.e. the 3rd branch of the superior division of the left MCA). CT perfusion demonstrates delayed perfusion in the posterior trunk of the superior division of the right MCA, which includes the thrombosed artery to the central sulcus. CTA confirms the occlusion of the posterior trunk of the right MCA superior division. There is good retrograde pial collateral confirmed on CTA and CT perfusion.
2. MR flair and MR diffusion confirm evidence of a focal infarction in the central intrasylvian insular cortex. Timeframe of stroke is hyperacute (<8 hours). In all likelihood the initial embolus was to the superior MCA division, which was collateralized. However, upon clot lysis, distal embolization occurred into the single artery to the central sulcus causing acute symptoms.
2. MR flair and MR diffusion confirm evidence of a focal infarction in the central intrasylvian insular cortex. Timeframe of stroke is hyperacute (<8 hours). In all likelihood the initial embolus was to the superior MCA division, which was collateralized. However, upon clot lysis, distal embolization occurred into the single artery to the central sulcus causing acute symptoms.
Lessons to be learned
1. This case illustrates evidence of a mismatch between the hyperdense single artery (artery to the central sulcus) on CTA and the CT perfusion where the prolonged TTP included an area much larger than could be expected for a single branch occlusion. The CTA demonstrated reduced filling rate for the posterior trunk of the superior division of the left MCA including the mid insular M3 hyperdense artery. This illustrates thrombi of differing age, and implies an initial thrombus which undergoes clot lysis and secondary embolization producing acute symptoms.
2. The CTA venocapillary pool defined how the actual site of stroke producing oligemia was confined not the entire perfusion zone for this artery, but rather to only a small area of the mid insular cortex. This area of reduced CT density in the venocapillary pool is confirmed as a hyperacute stroke on MR diffusion and FLAIR.
3. FLAIR demonstrated increased flow related signal in a branch off the posterior MCA trunk, which was not thrombus but just slow flow arterial signal. This can create confusion which limits FLAIR as a means of thrombotic occlusion. It is helpful in recanalized arteries when it is positive in the wall of the artery or vein.
5. Increased (subtle) CT density in the lateral cortex plus contrast leak in the high convexity MCA lateral cortex, plus venous hyperemia on SWI is consistent with post ischemic arteriopathy in the distal branches off the posterior trunk MCA; this matches the distribution of prolonged TTP but little or no rise in CBV on CT perfusion.
6. This case again demonstrates how each component of the stroke workup on CTA, CT perfusion & MR work in tandem to provide the whole picture of the ischemic event.
2. The CTA venocapillary pool defined how the actual site of stroke producing oligemia was confined not the entire perfusion zone for this artery, but rather to only a small area of the mid insular cortex. This area of reduced CT density in the venocapillary pool is confirmed as a hyperacute stroke on MR diffusion and FLAIR.
3. FLAIR demonstrated increased flow related signal in a branch off the posterior MCA trunk, which was not thrombus but just slow flow arterial signal. This can create confusion which limits FLAIR as a means of thrombotic occlusion. It is helpful in recanalized arteries when it is positive in the wall of the artery or vein.
5. Increased (subtle) CT density in the lateral cortex plus contrast leak in the high convexity MCA lateral cortex, plus venous hyperemia on SWI is consistent with post ischemic arteriopathy in the distal branches off the posterior trunk MCA; this matches the distribution of prolonged TTP but little or no rise in CBV on CT perfusion.
6. This case again demonstrates how each component of the stroke workup on CTA, CT perfusion & MR work in tandem to provide the whole picture of the ischemic event.
Recommendations
Watch the included summary video for this instructional case.