Abstract
Background and Purpose: Near occlusion (NO) is a description of the luminal diameter decrease or collapse of the distal internal carotid artery, owing to the severe stenosis of the carotid bulb. The goal of this study was to elucidate the pathogenesis of NO by histologically investigating carotid endarterectomy specimens.
Methods: We reviewed 38 continuous carotid endarterectomy specimens with severe stenosis (>85%; 95% with NO) using digital subtraction angiography. The uninterrupted plaques of the stenotic lesions were removed using carotid endarterectomy, sliced at 2-mm intervals, and histologically investigated using special staining.
Results: 11 out of 18 NO specimens (61%) histologically showed multiple remnant channels in occlusive thrombi or honey-comb patterns of neovascular channels, but only 1 out of 20 non-NO specimens showed such features.
Conclusions: The luminal narrowing or collapse of the distal internal carotid artery is caused by a significant decrease in perfusion pressure. Of the NO plaque specimens, 70% had histological findings of multiple and irregular luminal patterns in the acute or chronic occlusive thrombi caused by a rupture of the fibrous cap, which may be the cause of the extremely low perfusion pressure.
