Bow Hunter's stroke caused by a nondominant vertebral artery occlusion: case report

Bow hunter's stroke is a consequence of vertebrobasilar insufficiency as a result of mechanical occlusion or stenosis of the vertebral artery at the C1-C2 level by head rotation. In most cases, a dominant vertebral artery is involved. No case of bow hunter's stroke as a result of mechanical occlusion of a nondominant vertebral artery has ever been reported.

We describe a rare case of Wallenberg's syndrome caused by occlusion of a nondominant vertebral artery induced by head rotation. The patient complained of vertigo and paresthesia of the left face and the right extremities when he rotated his head 45 degrees or more to the right.

Dynamic angiography revealed that the left vertebral artery was smaller than the right, terminated in a branch of the posteroinferior cerebellar artery, and was stretched and completely occluded at the C1-C2 level with the head rotated 45 degrees to the right. The right vertebral artery was normal when the head was rotated to either the right or the left. Three-dimensional enhanced computed tomography with the head rotated 45 degrees to the right revealed that the left vertebral artery was stretched and occluded by dislodgment between C1 and C2. Cerebral blood flow scintigraphy with head rotation demonstrated that blood flow was decreased in the lower portion of the left cerebellar hemisphere. C1-C2 posterior fixation was performed to prevent life-threatening neurological accidents.

We emphasize that the diagnosis of bow hunter's stroke should be based not only on angiographic findings but also on hemodynamic studies with head rotation.