Rotational vertebral artery occlusion in a child with multiple strokes: a case-based update.

INTRODUCTION: Rotational vertebral artery occlusion (RVAO), sometimes known as "Bow hunter syndrome," is an important and diagnostically challenging cause of posterior circulation stroke in children. It is caused by impingement of osseous and/or ligamentous structures on the vertebral artery. DISCUSSION: We review the differential diagnosis and recommended workup for posterior circulation stroke in children. The anatomical cause for pediatric RVAO is most commonly an anomalous bone formation of the rostral vertebral column. Many bony anomalies have been associated with RVAO, including the "ponticulus posticus," a common anomaly of the C1 vertebrae. The definitive diagnosis of RVAO is made with dynamic angiography, and surgical decompression of the vertebral artery prevents recurrent strokes. ILLUSTRATIVE CASE: We report a 15-year-old boy with recurrent posterior circulation ischemic strokes caused by an anomalous ossification of the C1 vertebrae. Three-dimensional (3D) and multiplanar reconstructed CT images showed the anomalous C1 ossification, and cervicocerebral digital subtraction angiography (DSA) revealed an associated vertebral artery (VA) dissection. The patient was initially managed by head immobilization in a hard collar and anticoagulation for 3 months. After healing of the dissection that was confirmed angiographically, dynamic DSA demonstrated reversible occlusion of the VA during contralateral head turn. Surgical decompression of the VA was performed and confirmed by intra-operative DSA with head turning.
CONCLUSIONS: RVAO is an important diagnosis in children with posterior circulation stroke. Our case demonstrates the need for high clinical suspicion and careful analysis of 3D cervical spine CT images in children with posterior circulation stroke.