Contrast extravasation from basilar artery without aneurysm formation on digital subtraction angiography in computed tomography angiogram-negative subarachnoid hemorrhage: A case report

The causes of angiogram-negative subarachnoid hemorrhage (SAH) on initial angiography, which accounts for 10-30% of spontaneous SAH, are heterogeneous and still unclear. We report a case of nonaneurysmal SAH, in which initial computed tomographic angiography (CTA) showed no source of bleeding, but the subsequent digital subtraction angiography (DSA) revealed contrast extravasation from the basilar artery without aneurysms.A 67-year-old woman with a medical history of hypertension presented as SAH of World Federation of Neurological Surgeons Grade II. CTA on admission did not show any cause of bleeding and DSA was subsequently performed to show contrast extravasation from a perforator of the middle third of the basilar artery without aneurysms during the subsequent DSA, resulting in profound deterioration SAH and neurological status. The patient was conservatively treated. Follow-up DSAs on days 2 and 16 showed no source of bleeding as well.Although the precise cause of bleeding in this case is uncertain, SAH might be caused by local dissection of the basilar artery perforator, and the bleeding site might heal spontaneously without forming of a pseudoaneurysm.