A Subtype of Bow Hunter’s Syndrome Requiring Specific Method for Detection: A Case of Recurrent Posterior Circulation Embolism due to “Hidden Bow Hunter’s Syndrome”

Abstract

Objective: A condition that presents with recurrent embolism due to "hidden bow hunter's syndrome," a subtype of bow hunter's syndrome with a different pathogenic mechanism, is reported. Case Presentation:The patient was a 78-year-old male who exhibited recurrent embolic stroke of the posterior circulation territory resistant to medical treatment. DSA showed occlusion of the right vertebral artery (VA), but dynamic left vertebral arteriography (VAG) presented no change in blood flow. Since indirect signs of occlusion and recanalization of the right VA were retrospectively obtained, dynamic right VAG was performed again on another day, which revealed that the occluded right VA in the neutral neck position recanalized when the neck was rotated to the left. Suspecting that thrombi formed during occlusion scattered with recanalization, we performed embolization of the parent artery in the distal right VA for the prevention of recurrence. Conclusion:This pathological condition should be considered as a differential diagnosis if unexplained ischemia of the posterior circulation is accompanied by unilateral VA occlusion.Keywords▶ bow hunter's syndrome, vertebral artery stump syndrome, cryptogenic stroke, vertebrobasilar insufficiency, rotational vertebral artery compression

Hidden Bow Hunter's Syndrome Diagnosed Using Dynamic Cerebral Angiography and Successfully Treated with Spinal Surgery: A Case Report and Review of the Literature

“…HBHS is a rare cause of embolic ischemic stroke in the posterior circulation area. A thrombus forms while the affected VA remains occluded and moves to distal arteries when the VA recanalizes in a particular neck position ( 1 ). Only six cases, including our own, have been reported for HBHS or its equivalent in the English and Japanese literature ( 1 - 5 ).…”

“…Treatment options for HBHS include conservative treatment with antithrombotic drugs, parent artery occlusion of the affected VA and spinal surgery to decompress the affected VA ( 1 - 5 ), similar to BHS ( 7 ). Spinal surgery for HBHS (3 in 6 cases) appears to be safe and effective since recurrent stroke was prevented in all surgery cases without any perioperative complications.…”

“…Hidden bow hunter's syndrome (HBHS) is an extremely rare disease in which the vertebral artery (VA) occludes in a neutral position but recanalizes in a particular neck position ( 1 ). Such occlusion of the involved VA in the neutral neck position makes the diagnosis difficult.…”

Repeated cerebellar infarction in the affected nondominant vertebral artery distribution with reversible vertebral artery occlusion elicited by head tilt: illustrative case

“… 23 In a patient with transient occlusions of the VA by an osteophyte from a cervical vertebral body while changing neck positions and associated with repeated embolic infarction in the posterior circulation, a coil embolization procedure was performed at the distal portion of the affected VA to prevent further embolic infarction in the posterior circulation. 24 The current patient underwent C3–C6 left laminoplasty for ossification of the posterior longitudinal ligament 5 years ago, and posterior fusion of C3–C6 was subsequently selected. After surgery, he experienced no additional symptoms or further cerebellar infarctions.…”