A case report of recurrent posterior circulation infarction caused by bow hunter syndrome / 中国脑血管病杂志

ABSTRACT

Rotational vertebral artery occlusion syndrome, also known as Bow Hunter Syndrome (BHS), is a rare clinical syndrome that causes mechanical occlusion or stenosis of the vertebral artery during head and neck rotation or extension. Ischemia symptoms of the vertebral-basilar artery system often occur during head rotation and could rapidly improve with neutral position. In a few cases, BHS may result in arterio-arterial embolic infarction due to secondary thrombosis from intimai injury caused by repeated compression of the vertebral artery. The author reported a case of a young female patient with repeated posterior circulatory infarction caused by BHS. The patient suffered from sudden unresponsiveness,memory decline,and right limb inflexibility. There were no vascular risk factors in her past history,and no correlation between clinical symptoms and neck rotation. Neck rotation test by carotid ultrasound showed the blood flow of left vertebral artery was decreased and reversed when the neck rotated to the right. Head and neck CT angiography (CTA) and DSA examination showed left vertebral artery local protrusion at the junction of V3 and V4,which was considered as dissection or pseudoaneurysm. Left vertebral artery segment after axial transverse foramen was not visible on CTA during right head rotation. High resolution MR showed a membranous structure protruding into the lumen at the V3-V4 junction of the left vertebral artery. It is suggested that the clinical symptoms of BHS may be unrelated to neck rotation, but could only present as posterior circulation area infarction combined with ipsilateral vertebral artery imaging characteristics of limited range of dissection or pseudoaneurysm. Missed diagnosis and misdiagnosis may occur if the clinicians lack the corresponding understandings and knowledge. Therefore, in young patients with posterior circulation cryptogenic stroke,morphological changes of posterior circulation vessels should be carefully analyzed. If necessary,carotid ultrasound neck rotation test or dynamic DAS should be conducted to clarify whether BHS is involved.