Endovascular Treatment of Wide-necked Cerebral Aneurysms with an Acute Angle Branch Incorporated into the Sac: Novel methods of Branch Access in 8 Aneurysms

Abstract

Purpose: The optimal management of geometrically complex aneurysms remains challenging. The aim of this retrospective study was to evaluate the safety and feasibility of branch-selective technique (BT) in wide-necked aneurysms with an acute angle branch incorporated into the sac.

Materials and methods: Eight consecutive patients harboring wide-necked cerebral aneurysms with an incorporated, acute angle branch (mean, 30.4°) underwent coiling over an 18-month period. Dome-to-neck ratio ranged from 0.9 to 1.8 (mean, 1.2). Every procedure utilized BT, i.e., stent- or catheter-assisted coiling through the incorporated branch.

Results: Technical success was achieved in all cases. With the aim to avoid the risk of aneurysmal rupture during struggling intraaneurysmal wire navigation, a 'looping method' and retrograde approach of a preshaped 0.014' microcatheter (C or J) was used for branch access in five cases and a 'looping method' and antegrade approach in one case. In the remaining one, just the C-preshape was enough to directly enter the branch without intraaneurysmal wire navigation. Overall, stent-assisted coiling was performed in seven cases, while catheter-assisted coiling was undertaken in one. The only complication was thrombotic posterior inferior cerebellar artery occlusion in one case, which was recanalized after tirofiban infusion. New neurological deficits were not identified in any cases.

Conclusion: BT seems safe and feasible for wide-necked aneurysms with an acute angle branch incorporated into the sac. The looping method may offer safe access to the incorporated, acute angle branch and should be considered for replacement of the fearful intra-aneurysmal wire navigation.

Keywords: Branch-selective technique; Endovascular procedures; Intracranial aneurysm.

Fig. 1

Schematic illustration of looping methods in the anterior circulation. Microcatheter looping is well completed in the cavernous segment and terminus of the ICA. When the wire tip is checked by the orifice of a small branch, such as meningohypophyseal artery (black arrow), gentle push of the wire can make the looping of the wire in the cavernous ICA (A). Advance of the microcatheter over the wire then is necessary for microcatheter looping, which can be used for coiling of Pcom-ICA aneurysms. If a targeted aneurysm is located at the MCA bifurcation, an access to the incorporated branch requires a series of steps at the ICA terminus and MCA bifurcation: 1) the C or J-preshaped microcatheter tip is slightly advanced into the A1 segment over the wire (B), 2) the wire is withdrawn into the microcatheter in the proximal half of the C or J curve (C), 3) gentle push of the microcatheter makes it looped in the M1 segment because the empty distal half of the curve is prone to bend in this relatively straightforward and larger segment (D), 4) after advancing and placing this looped microcatheter in the gently curved parent artery past the aneurysm, the wire can come out of the microcatheter and access the incorporated branch retrograde via a new smooth track (E), 5) Once the wire enters the incorporated branch, it should be placed in a far distal branch. The looped portion then should be straightened before advance over the wire (F). According to the technique, stent-assisted coiling vs. catheter-assisted coiling, the need for exchanging microcatheters is determined.

Fig. 2

A 43-year-old male with a ruptured aneurysm incorporating the right PICA (Case 2). A. Working projection shows right PICA aneurysm with PICA incorporation. The PICA arises from the sac at an angle of -20° relative to the VA. B. Two microcatheters via the ipsilateral VA are shown in the aneurysm for dual-catheter technique in combination with branch-selective stent-assisted coiling. C. Roadmap image shows a looped microcatheter (black arrow) in the contralateral VA for the purpose of crossing the acute angle vertebral-vertebral junction and retrograde approach of the right PICA. The loop can be made in the posterior circulation through C2 or C3 branch like the A1 segment of the anterior circulation (open arrow). D, E. Roadmap image shows that the wire is out of the looped microcatheter in the basilar artery and placed far downward in the ipsilateral VA. F. Once the microcatheter is advanced to the PICA orifice over the wire (black arrowhead), the wire can access the PICA via a new retrograde smooth track. G. Roadmap image shows the microcatheter over the wire in the PICA. It should be exchanged for a stent delivery catheter for stent-assisted coiling. H. Subtraction angiogram obtained after the eighth coil placement reveals occluded PICA (white arrows). I. Completion angiogram obtained after intraarterial tirofiban injection (0.5 mg) shows the restored flow but some tiny clots at the proximal PICA (open arrowheads). The stent markers are barely identifiable due to digital subtraction (dotted line).

Fig. 3

A 50-year-old male with an unruptured MCA bifurcation aneurysm (Case 5), whose images are the ground of the Fig. 1B through 1f illustrations. A. Working projection shows a MCA bifurcation aneurysm with the inferior division incorporated into the sac (black arrow). The incorporated branch arises from the sac at an angle of 41° relative to the M1 segment. B. Completion angiogram obtained after stent-assisted coiling, whose steps are illustrated in Fig. 1., demonstrates complete occlusion of that aneurysm and normal flow in the inferior division. The stent markers are barely identified (dotted line). C. Follow-up angiogram at 12 months shows well exclusion of that aneurysm from the circulation.