Utility of intraoperative angiography during subaxial foramen transversarium decompression for bow hunter's syndrome.

Bow hunter's syndrome is an uncommon cause of vertebrobasilar insufficiency resulting from rotational compression of the extracranial vertebral artery. While positional compression of any portion of the extracranial vertebral artery has been reported to result in bow hunter's syndrome, the most common site of compression is the V2 segment as it passes through the foramen transversarium of the subaxial cervical spine. A 43-year-old woman presented with increasingly frequent pre-syncopal and syncopal episodes upon leftward head rotation. Pre-operative angiographic studies with the neck rotated to the left demonstrated occlusion of the left vertebral artery by a C4-5 osteophyte arising from the C4 uncinate process. The patient underwent microsurgical decompression of the vertebral artery at C4-5 through a standard anterior transcervical retropharyngeal approach. Selective vertebral artery intraoperative angiography performed with the head passively rotated to the left before and after left vertebral artery decompression showed marked improvement in the luminal diameter and blood flow. The patient's symptoms resolved post-operatively. This case illustrates the second instance of intraoperative angiography used to confirm adequate vertebral artery decompression for bow hunter's syndrome. Intraoperative angiography can be safely used to decrease the extent of vertebral artery decompression in order to minimize the risk of operative complications.