Lesion patterns and stroke mechanisms in concurrent atherosclerosis of intracranial and extracranial vessels.

BACKGROUND AND PURPOSE

Concurrent atherosclerosis of the intracranial and extracranial cerebrovascular system is common in Asians. The typical lesion patterns and the mechanisms of stroke in patients with concurrent stenoses are unclear. This study aimed to determine these stroke features of such patients in Hong Kong.

METHODS

We conducted a cross-sectional cohort study in a university hospital from January 2002 to December 2003. Consecutive Chinese patients with acute ischemic stroke underwent CT brain, MRI brain (with MR angiography and diffusion-weighted imaging sequences), and carotid duplex.

RESULTS

In total, 251 patients were included in the analysis. Of these, 109 (43%) had concurrent stenoses. Patients who had concurrent stenoses, as compared with those without concurrent stenoses, had more symptomatic stenoses (84% versus 58%; OR, 4.0; 95% CI, 2.1 to 7.3; P<0.001), more concomitant perforating artery infarct, pial infarct, and borderzone infarct (14% versus 4%; OR, 3.6; 95% CI, 1.4 to 9.7; P=0.007), more multiple diffusion-weighted imaging lesions (55% versus 37%; OR, 2.1; 95% CI, 1.3 to 3.4; P=0.005), and more infarcts in the territory of the leptomeningeal branches of middle cerebral artery (26% versus 13%; OR, 2.2; 95% CI, 1.2 to 4.3; P=0.01). In multivariate regression analysis, smoking; prior stroke; the presence of concomitant pial infarct, pial infarct, and borderzone infarcts; multiple diffusion-weighted imaging lesions; and symptomatic stenoses were significantly associated with concurrent stenoses. Among patients with concurrent stenoses, those who had tandem lesions, as compared with those who had nontandem lesions, had more perforating artery infarct and borderzone infarcts (27% versus 8%; OR, 4.3; 95% CI, 0.9 to 19.8; P=0.04); more concomitant pial infarct, pial infarct, and borderzone infarcts (18% versus 0%; P=0.02), and more multiple diffusion-weighted imaging lesions (65% versus 23%; OR, 6.2; 95% CI, 2.2 to 17.2; P<0.001). Infarcts in the territory of middle cerebral artery leptomeningeal branches and symptomatic stenoses were more common in patients with tandem lesions.

CONCLUSIONS

Concomitant perforating artery infarct, pial infarct, and borderzone infarcts; multiple diffusion-weighted imaging lesions, and infarcts in the leptomeningeal branches of the middle cerebral artery were more common in patients with concurrent stenoses, especially those with tandem lesions. This study suggested that the combination of hemodynamic compromise attributable to concurrent stenoses and artery-to-artery embolization is a common stroke mechanism in these patients.