Boundary zone infarcts

Some anterior circulation syndromes, usually classified as partial anterior circulation syndromes, are caused by boundary zone infarcts. The rare anterior choroidal artery distribution infarcts, which can be defined only by the CT or MRI pattern, are probably caused by microvascular disease as well as embolism, and they can lead to a partial anterior circulation syndrome or lacunar syndrome (Hupperts et al. 1994). 

Boundary zone infarcts occur in the border zones between arterial territories ... 

Low flow may occur secondary to systemic hypotension, as during cardiac arrest. This results in bilateral infarcts, usually in the posterior boundary zones, and causes cortical blindness, visual disorientation and agnosia, and amnesia. Alternatively, a relatively small fall in systemic blood pressure in the presence of internal carotid occlusion or stenosis may cause unilateral boundary zone infarction, usually in the anterior and subcortical regions. This causes contralateral weakness of the leg more than the arm, with sparing of the face. 

Aortic arch dissection can cause profound hypotension, with global, and sometimes boundary zone, cerebral ischemia or focal cerebral ischemia if the dissection spreads up one of the neck arteries. Clues to this diagnosis are anterior chest or interscapular pain, along with diminished, unequal or absent arterial pulses in the arms or neck and a normal electrocardiogram, unlike acute myocardial infarction, acute aortic regurgitation and pericardial effusion. 

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