Can the transverse foramen/vertebral artery ratio of double transverse foramen subjects be a risk for vertebrobasilar transient ischemic attacks?

The C6 is the cervical vertebra into which the vertebral artery enters the passage of the transverse foramen and it is the vertebra most affected by double transverse foramina. There is currently little information about the relation between the vertebral artery and the double transverse foramen in C6. We aimed to test whether subjects with a double transverse foramen in C6 have a reduced transverse foramen/vertebral artery ratio when compared with normal anatomy subjects who possess a single transverse foramen which may be a risk for transient vertebral artery stenosis. We measured the area of the transverse foramen and the vertebral artery in 27 double transverse and 56 normal anatomy subjects using computed tomography angiography. We found significant differences in the area of the transverse foramen between double transverse and normal subjects (P < 0.001) but not between the vertebral artery area of double transverse and normal subjects (P = 0.829). The subjects with double transverse foramina have a reduced transverse foramen/vertebral artery ratio, which may be a possible risk for transient vertebral artery stenosis.