Hemodynamic risk zone

Szabo et al. (2001) 102 >50 or occlusion Territorial stroke (n=30) Subcortical stroke ( =13) Territorial infarction with fragmentation (n=ll) Disseminated small lesions (n=15) Borderzone lesions (n=33) The degree of ICA stenosis may favor certain stroke patterns. In patients with high-grade stenosis the highest frequency of lesions occurs in the hemodynamic risk zones... 

Yet, since the territories of the major cerebral arteries have been shown to possibly vary considerably, lesion localization alone may not be enough to identify borderzone lesions. Van der Zwaan and Hillen (1991) described different variations of the cortical distributions in all 25 human brains obtained at autopsy through injecting different colored substances into the six major arteries of the human brain. He also noted an inter-individual difference with remarkable asymmetrical territorial distribution in both hemispheres. With the clinical use of novel MRI techniques, however, it is possible to identify acute ischemic lesions in individual hemodynamic risk zones. 

For the exact description of hemodynamic stroke and identification of individual hemodynamic risk zones, as mentioned earlier, the assessment of the hemodynamic situation is essential. PI offers a means to obtain semiquantitative hemodynamic information in cerebral ischemia with relatively high resolution and short acquisition times covering all cerebral vascular territories. In acute cerebral ischemia dynamic susceptibility contrast... 

Fig. 15.4. DWI shows examples of acute borderzone lesions, namely in the posterior (upper row left) or anterior (upper row right) hemodynamic risk zones and in the subcortical or deep borderzone (bottom row)...

Fig. 15.5. As in this 68-year-old man with a high-grade stenosis of the left internal carotid artery presenting with a fluctuating mild left-hemispheric syndrome, acute ischemic lesions can affect all areas considered to be hemodynamic risk zones...

Fig. 15.7. The theoretical concepts of stroke in hemodynamic risk zones - dot-like microembolic lesions in the most distal arterial branches resulting from more proximal vessel pathology and impaired emboli washout (left) and the complete infarction of the compromised tissue in the borderzone territory (right). The bottom row gives DWI examples of these lesion patterns...

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