case_images: PMC8571361_01
case_images: Computed tomography (CT) and CT angiography (CTA) on admission. (a and b) CT shows subarachnoid hemorrhage (SAH) predominantly in the posterior fossa. (c) CTA shows no cause of SAH.
case_images: SNI-12-498-g001.jpg
case_images: PMC8571361_01_SNI-12-498-g001.jpg
case_images: F1
case_images: CT of the head showed SAH of Fisher Group 3, especially in the prepontine cistern, and CTA showed no source of bleeding [Figure 1].
case_images: Digital subtraction angiography (DSA) on admission. DSA in an arterial phase (a, anteroposterior view) shows contrast extravasation (arrow) from a perforator of the middle third of the basilar artery, which is increased in a capillary phase (b, anteroposterior view; c, lateral view).
case_images: SNI-12-498-g002.jpg
case_images: PMC8571361_01_SNI-12-498-g002.jpg
case_images: F2
case_images: DSA also revealed no vascular lesion such as an aneurysm, but showed contrast extravasation from a perforator of the middle third of the basilar artery [Figure 2], although blood pressure was well controlled.
case_images: (a and b) Noncontrast computed tomography performed just after the initial digital subtraction angiography showing contrast extravasation with increasing amount of subarachnoid hemorrhage predominantly in the left cerebellopontine cistern.
case_images: SNI-12-498-g003.jpg
case_images: PMC8571361_01_SNI-12-498-g003.jpg
case_images: F3
case_images: The patient fell in a coma, and CT demonstrated an increase in the amount of SAH mainly in the posterior fossa [Figure 3].
case_images: Right vertebral artery angiography on days 2 (a, anteroposterior view; b, lateral view) and 16 (c, anteroposterior view; d, lateral view). (a and b) No source of hemorrhage is shown, and the wall of the basilar artery is smooth. (c and d) No cause of hemorrhage is revealed, but vasospasm of the basilar artery (arrow) is shown.
case_images: SNI-12-498-g004.jpg
case_images: PMC8571361_01_SNI-12-498-g004.jpg
case_images: F4
case_images: The second DSA performed on day 2 showed no source of SAH and the wall of the basilar artery was smooth [Figure 4a and b]. DSA performed on day 16 also showed no source of bleeding [Figure 4c and d].