A case of vertebral arterial dissection associated with parent artery occlusion initially manifesting as incident and secondary subarachnoid hemorrhage

We report a case of vertebral arterial dissection associated with parent artery occlusion initially manifesting as incident and secondary subarachnoid hemorrhage (SAH). The patient was a 64-year-old man. It had been noted earlier that his right vertebral artery was occluded when he underwent coronary artery bypass grafting 2 years previously. He was transported to our hospital in an unconscious state and with bilateral abducent nerve palsy. CT scans demonstrated SAH in his posterior fossa. Angiograms revealed right vertebral occlusion. We diagnosed SAH due to right vertebral arterial dissection associated with parent artery occlusion based on a series of studies. The said vertebral artery with the occlusion was considered as an incidental vertebral arterial dissection. Earlier, when there is nonhemorrhagic vertebral artery dissection with dilatation, the remaining findings may have the potential for SAH later. Based on the present data, we should consider that nonhemorrhagic vertebral artery dissection with occlusion has the potential for SAH later.