Anastomosis between the internal carotid and vertebral artery in the neck.

We report a case of anastomosis between the internal carotid and vertebral a. in the cervical region. This anatomic variation is due to incomplete migration during embryogenesis of the branchial aa., collaterals of the dorsal aorta, towards the ventral aorta. It does not involve persistence of a type I proatlantal a., as described by Lasjaunias. Such anastomoses must be recognised since they may modify surgical tactics in the context of endarterectomy for carotid stenosis.