Fig. 2

a 3D-DSA demonstrated a wide-necked (4.1 mm) basilar bifurcation aneurysm sized 4.9 mm with a daughter sac on the left lateral side of the sac. b and c Left proximal vertebral artery (VA) was dominant compared to the right VA so that we decided to select the left VA for a guiding catheter during endovascular treatment. d A 6-Fr guiding catheter could not pass through the tortuosity of the left VA at the proximal segment (a white arrowhead). There was asymptomatic dissection of the left VA (a white arrow). e With a 5Fr-guinding catheter in the right VA, a single microcatheter (Excelsior SL-10 straight) was navigated to the right posterior cerebral artery and we deployed a Neuroform Atlas stent (3.0 mm × 21 mm) from the right posterior cerebral artery to the basilar artery (black arrowheads). After deploying the stent, the microcatheter was placed just proximal to the stent deployed (a black arrow). f A 0.014-microwire and the same microcatheter were navigated easily through the stent to the aneurysm. g Coiling was performed. h The initial angiographic result showed a neck remnant of the aneurysm. (i) On 6-month follow-up angiography, the aneurysm was completely occluded