Basilar Artery Bifurcation Aneurysm: Giant Basilar Bifurcation Aneurysm, Mass Effect, Stent-Assisted Coil Occlusion with a Single Enterprise Stent, Complete Long-Term Occlusion, Good Clinical Outcome

  • Michael KirschEmail author
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A 47-year-old man presented with an aggravation of a previously known cervical spine-degeneration related neck pain and a new headache in November 2013. MRI revealed a 26 × 19 mm, eccentric, posterior-oriented basilar bifurcation aneurysm with an ill-defined neck, occupying the interpeduncular fossa with mass effect on the crura cerebri and the midbrain but with no perianeurysmal edema or subarachnoid hemorrhage (SAH). The aneurysm was treated by endovascular coil occlusion with HydroCoils (MicroVention) and bare platinum coils, assisted by a single Enterprise stent (Cerenovus). DSA follow-up over four years confirmed the complete obliteration of the aneurysm, while the P1 segments of each posterior cerebral artery (PCA) remained patent. The main topic of this presentation is the different ways to achieve permanent occlusion in large and giant aneurysms, among them the use of HydroCoils and the merits of stent-assisted coiling.


Basilar artery bifurcation aneurysm Giant aneurysm 3D HydroCoils Stent-assisted coiling 


A 47-year-old male presented with headache and an aggravation of a known cervical spine-degeneration neck pain in November 2013.

Diagnostic Imaging

MRI at the referring hospital showed a giant basilar bifurcation aneurysm occupying the interpeduncular fossa with mass effect on the crura cerebri and the midbrain (Fig. 1a). The subsequent diagnostic cerebral angiography confirmed the eccentric position of the 26 × 19 mm ovoid aneurysm posterior to the basilar bifurcation with incorporation of the origins of both PCAs into the presumably narrow but ill-defined aneurysm neck (Fig. 1b, c).
Fig. 1

MRI (axial T2WI (a)) of a basilar bifurcation aneurysm with compression of the midbrain. Diagnostic cerebral angiography (posterior–anterior view (b); lateral view (c) shows a posterior directed aneurysm of the basilar bifurcation with a cranio-caudal diameter of 26 mm, incorporating the origins of both PCAs. Considering the relation of the PCAs and the entrance level of the aneurysm are difficult to visualize, the actual neck of the aneurysm might be narrow

Treatment Strategy

Prevention of increasing mass effect and aneurysm rupture were the goals of the treatment, aiming to occlude the aneurysm while preserving the incorporated PCAs. Endovascular coil occlusion after reconstruction of the basilar artery bifurcation with crossing or single Enterprise stent(s) (Cerenovus) deployment was chosen.


Procedure, 09.12.2013: stent-assisted coil occlusion of a giant basilar artery bifurcation aneurysm

Anesthesia: general anesthesia; 5000 IU heparin (Heparin Natrium, B. Braun) IV

Premedication: 1 × 500 mg ASA (Aspirin, Bayer Vital) PO, 1 × 375 mg clopidogrel (Plavix, Sanofi-Aventis) PO the day before

Access: right femoral artery, 6F sheath 90 cm (Cordis); guide catheter: 6F Fargo 125 cm (Balt Extrusion); microcatheter: Prowler select plus (Cerenovus), Echelon 14; microguidewire: Silver Speed 14 (Medtronic)

Implants: Enterprise stent 4.5 × 22 mm (Cerenovus); 12 coils: 3× HydroFrame18 (20 mm/48 cm, 18 mm/50 cm, 16 mm/44 cm), 3× Cosmos18 (24 mm/68 cm, 22 mm/63 cm, 18 mm/59 cm), 6× VFC (2 × 15–20 mm/60 cm, 15–20 mm/40 cm, 10–15 mm/40 cm, 6–10 mm/30 cm, 3–6 mm/15 cm) (all MicroVention)

Course of treatment: The left vertebral artery was catheterized with a 6F Fargo catheter. DSA confirmed the aneurysm of the basilar artery bifurcation with a longitudinal diameter of 26 mm. The origins of both P1 segments appeared incorporated into the aneurysm neck. The aneurysm neck was most likely narrow, but the borders between the aneurysm neck and the P1 origins were difficult to determine. It was anticipated that control of the basilar bifurcation would be difficult to maintain during coil insertion. Microcatheter access to both PCAs was attempted and both equally attained, the right PCA was catheterized and an Enterprise stent (4.5/22 mm) was deployed from the right P1 segment to the distal segment of the basilar artery (Fig. 2ac). Thereafter, it was not possible to catheterize the left PCA through the shaft of the Enterprise stent because of the more acute angle. Furthermore, it was not possible to opacify the left P1 origin on road map fluoroscopy due to the contrast medium pooling in the aneurysm with delayed and faint filling of the efferent branches (Fig. 2d, e). It was decided to occlude the aneurysm with the above listed coils, with only a single stent protecting the basilar bifurcation. Attention was paid to an uncompromised perfusion of the unprotected left PCA origin. The aneurysm was catheterized through the stent struts and densely occluded with HydroCoils and bare platinum coils.
Fig. 2

Stent-assisted coil occlusion of a giant basilar bifurcation aneurysm. Fluoroscopy (pa and lateral views (a and b)) and DSA images (pa and lateral views (c and d)) of the Enterprise stent deployed from right P1 segment to basilar artery. The left PCA is not opacified in this early phase. A small aneurysm on the right aspect of the distal basilar artery between the superior cerebellar artery and the right P1 segment remained untreated. The aneurysm sac was subsequently occluded with a total of 12 coils only (e and f). The Enterprise stent supported the control of the ill-defined basilar artery bifurcation and allowed for dense coil packing adjacent to the aneurysm neck

Duration: 1st–12th DSA run: 180 min; fluoroscopy time: 88 min

Complication: postprocedural diplopia

Postmedication: 1 × 100 mg ASA PO daily forever, 75 mg clopidogrel PO daily for eight weeks

Clinical Outcome

The patient developed a postinterventional diplopia, which was most likely due to an increased mass effect of the aneurysm after coil occlusion. Double vision improved under temporary steroid medication and is now stable, the vision having been compensated with prism glasses. The headache did not improve, and the patient is still under analgetic medication. It is not clear if the cause of the chronic headache is the severe cervical spine degeneration or the persistent mass effect of the aneurysm.

Follow-Up Examination

A DSA follow-up examination (Fig. 3) after four years confirmed a complete occlusion of the aneurysm and the patency of the basilar artery bifurcation.
Fig. 3

Follow-up DSA in December 2017 ((a) pa; (b) lateral view), four years after the stent-assisted coil treatment, confirmed the complete occlusion of the aneurysm


The endovascular coil occlusion of large and giant wide-necked aneurysms has two critical aspects: the preservation of the efferent arteries and the stable exclusion of the aneurysm from the blood circulation. Several options are available for the protection of the afferent and efferent vessels from inadvertent occlusion during coiling. Among them, conventional stenting as performed in this case, is technically the most straightforward solution (Adeeb et al. 2016). The Y-stenting technique requires access to both efferent arteries and can therefore be challenging with an at least one-digit failure rate, as encountered in the patient reported in this chapter (Limbucci et al. 2016). Bifurcation stenting has the theoretical advantage of modifying the vessel geometry with straightening of the bifurcation (Sağlam et al. 2015). In the presented case, a pCONus device (phenox), a Barrel stent (Medtronic), or a PulseRider (Cerenovus) might have been alternative options for assisted coiling (Signorelli et al. 2017; Mühl-Benninghaus et al. 2017; Sheth et al. 2016). A single Enterprise stent, however, allowed for the protection of the basilar artery bifurcation and for dense coil packing. Dense packing requires the control of the aneurysm neck region including the parent artery. While loose packing is technically less demanding, coil compaction and partial aneurysm perfusion is a frequent consequence. Dense packing, on the contrary, can be a technical challenge and may increase the procedural risks and material consumption. In return though, a more stable aneurysm occlusion can be expected.

Different coil types show a variable liability to coil compaction. Both fibered coils (ev3) and hydrocoils (MicroVention) are more resilient to coil compaction resulting in aneurysm reperfusion than bare coils (Liebig et al. 2004; Brinjikji et al. 2015). In the presented case, the combination of the straightening of the right PCA due to the stent deployment, the dense coil packing during the initial treatment, and the effect of the implanted HydroCoils may have contributed to the persistent occlusion of this giant aneurysm. These effects are, however, difficult to control and anticipate. This is the reason why aneurysm recurrence necessitating multiple retreatments is still a concern with the endovascular coil occlusion of large and giant aneurysms.



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© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Institut für Diagnostische Radiologie und Neuroradiologie, Universitätsmedizin GreifswaldGreifswaldGermany

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