Internal borderzone infarction - A marker for severe stenosis in patients with symptomatic internal carotid artery disease

Background and Purpose-Among subcortical infarctions, internal borderzone i nfarcts (IBI) are considered to be separate entities from perforating arter y infarcts (PAI), The purpose of the; present study is to examine the relat ionship between the presence of IBI and the degree of angiographically defi ned internal carotid artery (ICA) stenosis in symptomatic patients. Methods-A review of 1253 brain CTs from patients recruited by the North Ame rican Symptomatic Carotid Endarterectomy Trial was performed, using templat es for the identification of subcortical and cortical vascular territories. Results-A total of 413 patients had visible ischemic lesions on the side ip silateral to their symptomatic ICA. Of these, 138 had PAI, 108 had IBI, 122 had cortical infarcts, and 45 had: a:combination of different lesions. Mea n (+/-SD) lesion diameter was larger for IBI (11.0+/-5.9 mm) than for PAI ( 7.1+/-4.7 mm):(P<0.001 for comparing 2 means). IBI was associated with high er degrees of ICA stenosis (P<0.001). Sixty-three percent df the patients w ith IBI had severe (70% to 99%) ICA stenosis compared with 42% of patients with PAI; 18% of the IBI patients had stenosis of 90% or more compared With 8% of the patients with PAI, Multiple logistic regression did not identify any patient characteristics as confounders. Conclusions-Among subcortical infarctions, IBI are associated with higher d egrees of ICA stenosis in symptomatic patients. Differentiating between int ernal borderzone and perforating artery infarcts is important, because each may arise::from different mechanisms, namely, carotid disease:and small-ve ssel disease, respectively.