Significance of Provocative Perfusion Computed Tomography for Evaluation of Bow Hunter Syndrome.

Bow hunter syndrome (BHS) is a rare vascular phenomenon of vertebrobasilar insufficiency caused by dynamic stenosis of the vertebral artery (VA) by osteophytes, fibrous bands, or disk herniation with neck rotation. We present a rare case of a patient with bilaterally patent VAs on neutral imaging and bilateral dynamic compression of VA with left head rotation. Provocation tests are critical toward understanding dynamic pathophysiology of BHS because normal neutral vascular imaging does not preclude diagnosis of BHS. Although dynamic angiography is the gold standard for diagnosis of BHS, cerebral angiography could be invasive and risky. Provocative test using perfusion computed tomography scan is a simple and noninvasive method to assess BHS on an outpatient basis.