Rotational vertebral artery insufficiency (bow hunter’s stroke) is the phenomenon of vertebrobasilar ischemia induced by passive or active head rotation, usually in the setting of contralateral vertebral artery compromise or occlusion. First described in a patient who experienced this phenomenon during archery (1), it was once considered a very rare condition, but has been described in several recent reports. Suspicion of the disorder is dependent upon an observant history from the patient. It is difficult to image well angiographically. Furthermore, some compromise of one or both vertebral arteries may be seen with extreme head rotation in a sizeable proportion of the normal population, which diminishes the physiologic reserve when additional pathologic extrinsic compression of the artery supervenes (2,3). It is likely, therefore, that this is an underdiagnosed condition.

Typically, the occlusion or stenosis of the vertebral artery is described as occurring at the C1 to C2 level due to prominence of a bony spur or outgrowth impinging on the course of the artery (Figs. 28-1 and 28-2). However, it can happen anywhere in the cervical spine related to a variety of developmental bony anomalies, big uncovertebral osteophytes, fibrous bands, thyroid cartilage, or herniated discs (4,5,6,7,8,9,10). The posterior circulation is usually isolated and the contralateral vertebral artery is small or occluded, leaving the posterior circulation vulnerable to compromise of the only arterial supply remaining. The phenomenon has also been described in nondominant vertebral arteries where the artery terminates in an ipsilateral posterior inferior cerebellar artery (11). While the condition is most commonly seen in adults with degenerative uncovertebral disease, it may also present in children or young adults with anomalous bony cervical configurations (12,13). In children it is thought likely that transient ischemia of the posterior circulation does not occur due to greater resilience of collateral pathways, and therefore the phenomenon is more likely to present in children with established infarctions due to thromboembolic complications or arterial dissection (14). With repetitive injuries or sudden nonphysiologic movement, such as in chiropractic manipulation, complications of dissection and thromboembolic ischemia are well-recognized events (1,15,16,17). Similar dynamic states of compromise and ischemia can be seen with the internal carotid artery but are likely much rarer (18), due to the anatomic mobility of the carotid artery.