Morphology of anterior and posterior parts of the circle of Willis
| Patterns of Circle of Willis | Group A, Unilateral Stenosis (n = 86) | Group B, Contralateral Occlusion (n = 21) | Group C, Bilateral Severe Stenosis (n = 10) | |||
|---|---|---|---|---|---|---|
| Ischemia (n = 11) | No Ischemia (n = 75) | Ischemia (n = 12) | No Ischemia (n = 9) | Ischemia (n = 0) | No Ischemia (n = 10) | |
| Anterior part | ||||||
| Complete | 10 | 59 | 4 | 5 | ND | 4 |
| Indeterminate | 0 | 10 | 3 | 4 | ND | 3 |
| Incomplete | 1 | 6 | 5 | 0 | ND | 3 |
| Posterior part | ||||||
| Complete | 2 | 5 | 0 | 4 | ND | 2 |
| Indeterminate | 0 | 15 | 0 | 1 | ND | 1 |
| Incomplete | 9 | 55 | 12 | 4 | ND | 7 |
Note.—ND indicates no data. In the anterior part, complete type corresponds to a and b; indeterminate type, c; and incomplete type, d and e in Fig 1A. In the posterior part, complete type corresponds to a; indeterminate type, b1 and b2; and incomplete type, c and d in Fig 1B.