Relationship between HICH and development of Willis’ Circle
| Development of Willis’ Circle | Without HICH (n=203) | HICH (n=7) | P value |
| GC of both anterior and posterior circulation | 39 | 0 | <0.001 |
| GC of anterior circulation, PC of posterior circulation | 63 | 0 | |
| PC of anterior circulation, GC of posterior circulation | 37 | 0 | |
| PC of both anterior and posterior circulation | 64 | 7 |
GC, Good compensation; PC, Poor compensation.