Table 1

 Prevalence of angiographic collateral pathways

Circle of WillisOther pathwaysTotal
NoneOph onlyLM onlyBoth
Values are mean (SD). ACoA, anterior communicating artery; PCoA, posterior communicating artery; Oph, ophthalmic artery; LM, leptomeningeal anastomosis.
ACoA only920213
PCoA only345113
Both ACoA and PCoA31105
No collateral flow036211
Total151012542