Results of classification of vertebrobasilar abnormalities in 385 patients
| Atherosclerosis (S) | 28 | (7.3%) |
| Occlusive condition (O) | 18 | (4.7%) |
| Hypoplastic vertebral artery (H) | 23 | (6.0%) |
| Aneurysm (A) | 6 | (1.6%) |
| S + O | 10 | (2.6%) |
| S + H | 3 | (0.8%) |
| S + O + A | 2 | (0.5%) |
| Total | 90 | (23.4%) |