Figure legends
Figure 1a-d: Axial view of the initial computed tomography (a) showing left dominant intraventricular hemorrhage and hydrocephalus with a small amount of subarachnoid hemorrhage along both frontal sulci. Diffuse brain swelling can also be seen. Left internal carotid artery (ICA) digital subtraction angiography (DSA) (b) with an anterioposterior view showing occlusion of the supraclinoid ICA and basal and leptomeningeal collateral vessels representing Moyamoya disease. A pseudoaneurysm about 4.5 mm in size can also be seen at the distal branch of the left posterior choroidal artery (red arrow). Left vertebral artery DSA (c) also shows a 4 mm sized pseudoaneurysm at the left posterior choroidal artery (red arrow). (d) The frontal branch of the superficial temporal artery was selected as the donor artery for the first revascularization surgery (yellow arrow).
Figure 2a-f: T2 weighted brain magnetic resonance imaging (MRI) after the first superficial temporal artery-middle cerebral artery anastomosis bypass (a) showing perilesional edema with herniated brain tissue via the craniectomy site at the left frontoparietal lobe. Basal brain single photon emission computed tomography (SPECT), b) showing luxury perfusion in the herniated and swollen left frontotemporal lobe. Immediate post-bypass intraoperative findings (c-d) showing severe brain edema and patent anastomosis. T2 weighted image from four months after the second bypass surgery. Follow-up MRI (e) showing resolved edema and herniated brain tissue at the left frontoparietal lobe. Five months after the second bypass surgery, follow-up basal brain SPECT (f) reveals recovered luxury perfusion at the left frontotemporal lobe.
Figure 3a-h: Cerebral angiogram (Figure a-d) after rebleeding attack. Left internal carotid artery (a) and vertebral artery (b) digital subtraction angiography (DSA) showing an increased size of the pseudoaneurysm compared with preoperative DSA (Figure 1b-c) to about 13 mm at the longest diameter (red arrow). Left external carotid artery angiogram (c-d) showing non-patent superficial temporal artery-middle cerebral artery anastomosis (dotted white arrow) after the first bypass surgery. Selective lateral posterior choroidal angiogram and stand-alone coiling of the re-ruptured pseudoaneurysm (e-f) preserving the lateral choroidal anastomosis branches were performed. Postoperative six-month follow-up angiography (g-h) showing total obliteration of the pseudoaneurysm, the disappearance of the medullary tributaries from the left lateral posterior choroidal artery, and patent anastomosis (dotted black arrow).