Score* | ACoA | PCoA |
---|---|---|
2 | Intact ACoA and both A1 segments | Dominant PCoA† |
1 | Intact ACoA and unilateral hypoplastic A1 segment‡ | Non-dominant PCoA§ |
0 | No ACoA or absence of unilateral A1 | Fetal type PCoA, perforating PCoA, no PCoA, |
*Total score=ACoA+right PCoA+left PCoA (maximum score=6, minimum score=0). If the ICA is occluded, the ACoA and PCoA scores of the same side are considered to be 0. If both VAs are occluded, both PCoA scores are considered to be 0.
†The PCoA diameter is >50% of the P1 diameter in angiography.
‡The A1 diameter is ≤50% of the contralateral diameter in angiography.
§The PCoA diameter is ≤50% of the P1 diameter in angiography.
ACoA, anterior communicating artery; ICA, internal carotid artery; PCoA, posterior communicating artery; VA, vertebral artery.