External carotid-vertebral artery anastomosis for vertebrobasilar insufficiency.
Two patients with previous brain stem infarction and current symptoms of vascular insufficiency in the basilar circulation had evidence of vertebral artery occlusive disease. Angiography demonstrated ostial stenosis of the dominant right vertebral artery and retrograde flow down the left vertebral artery to the level of the transverse process of C2 in the first case and to the level of a severely stenosed origin in the second case. Carotid circulation was patent in both cases. The blood flow in the posterior circulation was patent in both cases. The blood flow in the posterior circulation was augumented by extracranial anastomosis of the external carotid artery to the vertebral artery in the foramen transversarium at the level of C1-2 by a lateral approach in Case 1 and at the level of C4-5 by an anterior approach in Case 2. Postoperative improvement in neurologic status occurred in both cases.