The brain appears to have a surprising tolerance for microembolization in the acute setting. Thus, carotid angioplasty may dislodge plaque fragments, but there may still be a low incidence of stroke. However, even small plaque fragments, less than 200 microm, may cause neuronal ischemia at later time points. Periprocedural microemboli could cause subtle neurologic dysfunction in late follow-up.

Surface irregularities were revealed by means of submillimeter resolution of the carotid plaques with MRI to be common, but only the presence of major irregularities correlated with the patient having TIA or stroke. Lumen shape and plaque location did not appear to predict stroke risk, but may effect imaging accuracy in determining the degree of stenosis. These data further define the relationship of plaque irregularity and cerebrovascular symptoms caused by atheroemboli.

During analysis of carotid plaque anatomy for a multicenter carotid imaging trial, we examined plaque specimens from 5 patients with double internal carotid artery lumina. Four of the 5 patients had symptoms referable to the lesion. The second lumen was noted when the plaque specimens were examined ex vivo with high-resolution (200 microm(3)) magnetic resonance imaging. Plaque structure was correctly identified in only 1 patient preoperatively. However, during retrospective review of the preoperative imaging studies, the second internal carotid artery lumen was identified in 3 patients.