Effect of collateral circulation on cerebral infarction in patients with severe internal carotid artery stenosis or occlusion

Objective: To investigate the relationship between the status of collateral circulation and cerebral infarction in patients with severe internal carotid artery stenosis or occlusion. Methods: Sixty-two patients with internal carotid artery stenosis >70% (6 patients had occlusion) detected by cerebral angiography were divided into symptomatic group (n = 41) and asymptomatic group (n = 21). The infarctions were divided into small perforating artery infarction, large perforating artery infarction, cortical artery territory infarction, massive cerebral infarction, and watershed-zone infarction according to the location, size and shape of infarction on brain MRI. The relationship between collateral circulation and cerebral infarction was analyzed by observing the integrity of the circle of Willis and other collateral pathways. Results: 1 In the symptomatic group, 8 patients had small perforating artery infarction, 6 had large perforating artery infarction, 9 had both small and large perforating artery infarction; 2 had cortical artery territory infarction, and 2 had massive cerebral infarction. Ten patients had watershed-zone infarction, and 4 had perforating artery infarction complicated with watershed-zone infarction. In the asymptomatic group, 1 patient had watershed-zone infarction, 7 had perforating artery infarction complicated with watershed-zone infarction, and 13 had no infarction. 2 In the symptomatic group, 5 patients had integrated anterior and posterior Willis circle, 12 had integrated anterior part of Willis circle, 8 had integrated posterior part of Willis circle, and 16 both the anterior and posterior part of Willis circle were not integrated. In the asymptomatic group, 14 patients had integrated anterior and posterior circle of Willis, 4 had integrated anterior part of Willis circle, 2 had integrated posterior part of Willis circle, and 1 both the anterior and posterior part of Willis circle were not integrated. The degree of patency of the Willis circle in the symptomatic group was lesser than that in the asymptomatic group (P<0.01). 3 Collateral flow from ophthalmic artery, anterior cerebral artery and posterior cerebral artery presented in the symptomatic group in 3, 8, and 5 cases, respectively, and in 1, 6, and 3 cases respectively in the asymptomatic group. There was no statistical difference between the 2 groups (P >0.05). Conclusion: In patients with internal carotid artery stenosis, the presence of cerebral infarction and cerebral ischemic symptoms are associated with the integrity of the Willis circle, and may not be associated with the secondary collateral flow pathways.