A Case of Intracranial Vertebral Artery Dissection Undetected by CT, MRI, and MRA at the Onset of Headache That Caused Subarachnoid Hemorrhage Seven Days Later

一例颅内椎动脉夹层，发病时CT、MRI和MRA均未检出，导致头痛，7天后发生蛛网膜下腔出血。