Intracranial aneurysms are a significant cause of morbidity and mortality, with endovascular treatment emerging as a primary therapeutic approach. The advent of stent-assisted coiling has greatly enhanced the efficacy of endovascular management, particularly for wide-necked and complex aneurysms. However, stent placement carries potential complications, including thromboembolic events, in-stent stenosis, and stent dislodgement. Stent dislodgement is a rare but serious complication that can compromise the success of the procedure and pose significant risks to the patient [1,2,6,7]. Understanding the causes, management strategies, and preventive measures associated with stent dislodgement is essential to improving patient outcomes. This case report aims to present our experience with stent dislodgement during the treatment of an intracranial aneurysm, highlighting the challenges faced, management strategies employed, and lessons learned from this complication.

A 73-year-old woman was incidentally diagnosed with an unruptured basilar tip aneurysm. Cerebral angiography revealed a cranially projecting 10×9 mm saccular aneurysm with a 9.3-mm-wide neck at the basilar tip (Fig. 1). The aneurysm incorporated both posterior cerebral arteries (PCAs). Considering the aneurysm’s location and size, as well as the patient’s age, stent-assisted coiling using the Y-stent technique was recommended. At this institution, the crossing Y-stent technique is commonly used for treating complex, widenecked bifurcation aneurysms, with a pair of Neuroform Atlas stents (NAS) preferred for establishing a “Y” configuration [5]. For this technique, a second stent is advanced over the wire through the interstices of the first stent and into the contralateral branch vessel. The patient was started on dual antiplatelet therapy with clopidogrel (75 mg/day) and acetylsalicylic acid (100 mg/day) seven days prior to the intervention. The procedure was performed under moderate sedation according to the ASA classification. Sedation was achieved using a dexmedetomidine infusion of 0.2 to 0.7 mcg/kg per hour. Full anticoagulation was maintained with an initial bolus of 4,000 units of intravenous heparin, followed by additional doses to keep the activated clotting time at 2 to 3 times the baseline. A 6-Fr Shuttle (Cook Medical, Bloomington, IN, USA) was positioned in the left proximal subclavian artery via a transfemoral approach and a 6-Fr intermediate catheter was used to navigate to the vertebrobasilar system. For stent deployment and coiling, a Phenom 17 microcatheter (Medtronic, Irvine, CA, USA) and Synchro 14 microwire (Stryker, Kalamazoo, MI, USA) were employed. A 3×15 mm NAS was selected as the first stent and deployed across the aneurysm neck, extending from the mid-portion of the P1 segment of the right PCA to the upper basilar artery. Although the initial stent position was slightly more distal than planned and appeared somewhat shorter, it adequately covered the aneurysm neck (Fig. 2). To establish the “Y” configuration, a Phenom 17 microcatheter and Synchro 14 microwire were used to access the left PCA through the interstices of the first stent. Unfortunately, forward migration of the deployed stent occurred, leading to dislodgement of its proximal end into the aneurysm sac. Digital subtraction angiography confirmed that the proximal stent markers had shifted into the aneurysm (Fig. 3). Due to the instability of the stent, placement of a second stent through the interstices of the first was not attempted. To ensure patency of the contralateral PCA, an attempt was made to place the second stent on the opposite side. However, due to the sharp angle between the left PCA and the basilar artery, it was extremely difficult to navigate the microwire into the left PCA. Eventually, a simple coil embolization was attempted without an assistance device, but initial efforts were unsuccessful due to inadequate aneurysm neck coverage. The coil loops herniated past the stent and into the parent vessel. After unsuccessful attempts at conventional stent-assisted coiling due to stent dislodgement and limited access, a rescue waffle cone technique was considered. This technique was chosen to achieve stable neck coverage and maintain patency of the parent vessel, given the complex aneurysmal anatomy. A Solitaire AB 4.0×20 mm (Medtronic, Irvine, CA, USA), a retrievable stent with sufficient radial force and navigability, was deployed with its distal end partially inserted into the aneurysmal sac. Coiling was performed through the expanded, cone-shaped distal end of the stent while maintaining parent artery patency (Fig. 4). With Solitaire AB stent assistance, coil embolization of the aneurysm was successfully completed. A total of seven coils (total length: 82 cm) were safely placed into the aneurysm sac, and immediate post-procedural occlusion was classified as Raymond-Roy Occlusion Classification (RROC) grade III (subtypes A+B), indicating incomplete occlusion with residual aneurysmal sac (Fig. 5). The patient tolerated the procedure well and continued daily dual antiplatelet therapy. At her 10-month clinical follow-up, she remained neurologically intact with no observed deficits.

Stent dislodgement during intracranial aneurysm treatment is a challenging complication that requires prompt recognition and appropriate intervention. Various factors contribute to this complication, including vessel tortuosity, improper stent deployment, inadequate stent apposition, and anatomical variations. In our case, the dislodgement may have been influenced by a combination of these factors, highlighting the need for meticulous pre-procedural planning and intraoperative adjustments. The most regrettable aspect of the stent dislodgement was the failure to select a longer stent as the initial choice. Additionally, choosing other types of stents, such as retrievable stents, could have been a useful option. However, the use of open-cell stents is preferred in stent-assisted coiling, and a pair of NAS stents is primarily used to establish a “Y” configuration at this institution [5].

Management strategies for stent dislodgement vary depending on the specific circumstances of the case. Options include repositioning the dislodged stent using a microcatheter or retrieval device, deploying an additional stent to stabilize the construct, or, in extreme cases, surgical removal [1,2,6,7]. The decision-making process should be guided by the patient’s clinical stability, the location of the dislodged stent, and the risk of further complications. In a situation similar to this case, the rescue waffle cone technique using a Solitaire AB stent could also be considered as a viable option for managing the crisis [3,4]. In our case, the Solitaire AB stent was chosen for the rescue waffle cone technique due to its favorable mechanical and procedural characteristics. Its fully retrievable design provides flexibility during deployment, allowing for repositioning if needed—an essential feature in emergent or salvage situations. Moreover, the high radial force and reliable conformability of the Solitaire AB stent offer adequate neck coverage and scaffold support for coil embolization when deployed in a cone-shaped fashion at the aneurysm base. While there is no consensus regarding the optimal stent for the waffle cone technique, devices such as the Solitaire AB or LVIS Jr. stents have been proposed in the literature and clinical practice, primarily due to their navigability and structural integrity in bifurcation aneurysms. In this case, the Solitaire AB was selected based on operator familiarity, availability, and the device’s compatibility with a 0.021-inch microcatheter, which facilitated smooth access in the tortuous basilar artery anatomy.

Based on a literature review, two notable case reports describe stent dislodgement during intracranial aneurysm treatment. Broadbent et al. [1] described two cases of stent dislodgement into large aneurysms; in one, successful re-access and rescue stenting were performed, while in the other, the parent vessel was sacrificed. Our case resembles the former in terms of strategic rescue planning. Chapot et al. [2] reported on bailout stentectomy of self-expandable intracranial stents. Their retrospective review identified 37 cases of stentectomy out of 3,341 aneurysms treated endovascularly, highwnslighting the occurrence of stent-related complications and the need for retrieval techniques.

Preventing stent dislodgement begins with careful patient selection and a thorough understanding of the vascular anatomy. High-resolution imaging and pre-procedural simulations can aid in choosing the appropriate stent size and deployment strategy. Additionally, ensuring adequate stent expansion and apposition through careful manipulation of the microcatheter and guidewire can minimize the risk of displacement. A key factor contributing to the dislodgement in this case was the selection of a stent that was both too short and placed too distally. These procedural choices may have compromised optimal anchoring within the parent vessel. This emphasizes the need for meticulous pre-procedural stent length planning and landing zone selection.

This case highlights the importance of operator experience, real-time decision-making, and access to advanced endovascular tools in managing stent-related complications. Further research and advancements in stent technology may help reduce the incidence of stent dislodgement and improve the overall safety profile of endovascular aneurysm treatment.

Stent dislodgement is a rare but potentially serious complication in the endovascular treatment of intracranial aneurysms. Our case highlights the importance of meticulous pre-procedural planning, careful stent selection, and real-time adaptability during intervention. The successful application of the rescue waffle cone technique demonstrates its effectiveness as a salvage strategy when conventional approaches are not feasible.