Proximal artery occlusion

The efficacy of IV thrombolysis in patients with moderate-to-severe strokes due to proximal arterial occlusions is restricted by several factors, including the relatively short therapeutic window, poor recanalization rates as the clot burden increases, restrictive eligibility criteria, and the risk of intracerebral hemorrhage. Endovascular techniques improve the rates of recanalization in this patient population, and appear to increase the likelihood of a good functional outcome. Intravenous thrombolysis... 

Copen, W.A., et al., Existence of the diffusion-perfusion mismatch within 24 hours after onset of acute stroke dependence on proximal arterial occlusion. Radiology, 2009. 250(3) p. 878-86. 

The largest study to date involving 109 patients with anterior circulation strokes was recently reported by Copen et al. [27]. All patients had diffusion/perfusion MRl within 24 h of stroke onset, and more than 50% had DWl/MTT mismatch volume of 160% or greater. This mismatch was most common among patients with proximal artery occlusions involving the distal internal carotid artery and/or the proximal middle cerebral artery identified by CTA or MRA. Of particular interest was the observation that there was no difference among patients who were scanned at different times after ictus 69% of patients who were scanned within 9 h had a 160% mismatch, which was very similar to the 68% of patients who were scanned after 9 h. The authors concluded that persistence of mismatch after 9 h is common and occurs most often in patients with proximal occlusions of the anterior circulation. 

Fig. 9.5 Stability of perfusion/diffusion mismatch for 4 h. Serial MRl scans that included diffusion and perfusion were acquired in 14 patients. Patients presented at an average of 7.1 h after stroke onset. All the 14 patients had anterior circulation proximal artery occlusion and were not eligible for thrombolytic...

Is there a proximal artery occlusion causing a significant stroke syndrome ... 

Parenchymal imaging to characterize the infarct core and the ischemic penumbra follows the identification of a treatable anterior circulation arterial occlusion in considering whether to proceed to endovascular recanalization. Even with endovascular therapy, greater than half (54-72%) of acute stroke patients with proximal artery occlusions have a poor outcome, and a significant fraction (16-44%) are dead at 90 days [47]. Certainly some of this morbidity and mortality are related to suboptimal or delayed reperfusion, but a significant proportion is likely secondary to infarcts that have already completed or are near completion before the initiation of therapy [47]. The major issue is the lack of appropriate patient selection. 

In anterior circulation proximal artery occlusions, core infarct size is inversely correlated with the degree of collateral flow to the ischemic bed... 

The major limitation to using CTA-SI to estimate the infarct core is the requirement that image acquisition occurs during a steady-state concentration of intravascular contrast. With the advent of faster, multidetector CT scanners, CTA imaging likely occurs during the upslope of the concentration-time curve and thus violates the steady-state assumption. It has been demonstrated that CTA-SI can significantly overestimate the DWI lesion primarily in patients with proximal artery occlusions [97]. 

The successful recanalization of an anterior circulation proximal artery occlusion will be of benefit to the patient only if it results in the prevention of infarction of brain tissue put at risk by that occlusion. Reperfusion into irreversibly injured tissue will not improve symptoms and may place the patient at risk for a hemorrhagic... 

A simpler approach to identifying a significant penumbra is the combination of a proximal artery occlusion, significant clinical deficit (NIHSS score >10), and small core infarct (<70-100 mL)... 

The large-scale trials of endovascular stroke therapy upon which current practice is based [6,12,14,15] utilized three primary inclusion criteria the presence of a proximal artery occlusion, a significant neurologic deficit (e.g., NIHSS score >8), and time from symptom onset to treatment within 6-8h. (Table 12.5) Importantly, assessment of parenchymal injury was performed with... 

Major strokes secondary to proximal artery occlusions represent the most devastating ischemic stroke subtype. Intra-arterial revascularization strategies are the best... 

Hakimelahi R, Copen WA, Schaefer PW, Wu O, Yoo AJ, Schwamm LH, Gonzalez RG (2009) A small DWl lesion in the setting of an anterior circulation proximal artery occlusion predicts the presence of a large diffusion-perfusion mismatch. American Society of Neuroradiology Annual Meeting, Vancouver, British Columbia... 

Fox AJ, Vinuela F, Pelz DM, et al. (1987) Use of detachable balloon for proximal artery occlusion in the treatment of unclippable cerebral aneurysms. J Neurosurg 66 40-46... 

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