Risk Factors:
- age
- gender
- migraine headaches
- hypertension
- diabetes
- smoking
- oral contraceptives
- fibromuscular hyperplasia
- syphilis
- cystic medial degeneration
- Marfan's syndrome
- Precipitating events (leading to vertebrobasilar artery dissections)
§ cervical manipulation
§ certain sports activities (Haldeman, 1976)