Surgical possibilities in the third portion of the vertebral artery (above C2). Anatomical study and report of a case of anastomosis between subclavian artery and vertebral artery at C1-C2 level.

A reappraisal of surgical possibilities in the third portion of the vertebral artery (VA) above C2, has been done from an anatomical study on twenty autopsy specimens. A route passing between the internal jugular vein and the Sterno-cleido-mastoid muscle allows a simple approach to the transverse process of C1. After division of two muscles attached to this process, 1.5 cm of the VA can be exposed. For larger exposure of the artery, the foramen transversarium of C1 must be unroofed and the artery dissected in the guttering of the posterior arch of the atlas. This surgical route was used in a case of aneurysmal dysplasia at the C3 level. An anastomosis between the subclavian artery and VA at the C1-C2 level was performed with an autologous saphenous vein graft. The key points are the highest possible freeing of the XI nerve and the head position. Rotation and extension move the transverse process and the posterior arch of the atlas superficially and anteriorly.