LAUSR

BACKGROUND Although an asymptomatic spinal dural arteriovenous fistula (SDAVF) can sometimes be incidentally detected on magnetic resonance imaging (MRI), there are no previous reports showing the development of an SDAVF on MRI or magnetic resonance angiography (MRA). CASE DESCRIPTION A 64-year old man with unruptured vertebral artery dissection (VAD) developed a subarachnoid hemorrhage (SAH) during regular follow-up. Emergent endovascular coil internal trapping for the VAD was performed; however, angiography after the endovascular treatment showed a lower cervical SDAVF. The SDAVF was considered the bleeding source based on subsequent spinal MRI, and endovascular embolization was performed. In this case, previous serial MRA examinations indicated that the SDAVF appeared for the first time during follow-up, and SAH occurred. CONCLUSIONS This may be the first report in which serial MRA studies demonstrated the course of this condition, from the appearance of an SDAVF to the development of SAH. An abnormal vascular structure detected on MRA indicated abnormal enlargement of the perimedullary vein and the presence of a cervical SDAVF. A lower cervical SDAVF should be suspected if such an abnormal vascular structure is detected on MRA.