Post-Detachment Displacement of a Woven EndoBridge (WEB) Device Managed via Microcatheter Manipulation: A Case Report

Abstract

Objective

To report a case of post-detachment Woven EndoBridge (WEB) displacement successfully managed through microcatheter manipulation alone, avoiding unplanned stenting, which necessitates long-term dual antiplatelet therapy.

Case Presentation

A 42-year-old male presented with an unruptured middle cerebral artery bifurcation aneurysm. Device sizing was planned using high-resolution 3D DSA and volumetric analysis on a Siemens ARTIS icono biplane (ARTIS icono VE20 software; Siemens Healthineers, Erlangen, Germany). A WEB SL 5 × 3 mm device (Terumo Neuro, Tustin, CA, USA) was deployed and detached. However, the subsequent withdrawal of an adjunctive microcatheter from a branch vessel caused vascular recoil, leading the detached WEB to rotate and protrude toward the branch orifice, compromising distal flow. Instead of rescue stenting, we performed a “pushing technique” using a Leonis Mova microcatheter (SB-Kawasumi Laboratories, Kanagawa, Japan). The device was successfully reseated within the aneurysm sac, albeit with a 90° rotation. Final angiography confirmed stable seating and excellent branch patency. The patient was discharged without neurological deficits on single antiplatelet therapy.

Conclusion

Post-detachment WEB displacement can occur due to dynamic vascular shifts even with precise volumetric sizing. Microcatheter manipulation is a feasible alternative bailout option that preserves the low-profile advantages of the WEB device and avoids the risks associated with rescue stenting.

Introduction

The Woven EndoBridge (WEB; Terumo Neuro, Tustin, CA, USA) has emerged as a transformative intrasaccular flow disruption device for the management of wide-neck bifurcation aneurysms (WNBAs).¹⁾ By achieving definitive occlusion from within the aneurysm sac, the WEB device offers the distinct advantage of avoiding permanent endoluminal implants in the parent artery, thereby circumventing the requirement for mandatory long-term dual antiplatelet therapy (DAPT). Recent clinical experience has demonstrated that the introduction of the WEB device has significantly shifted the treatment paradigm for WNBAs toward a lower-profile, endovascular approach.¹⁾

Despite its established safety and efficacy, technical complications such as post-detachment device displacement—including rotation, migration, or protrusion—pose significant intraoperative challenges. Data from multicenter series indicate that an abrupt change in device orientation immediately following release occurs in approximately 4.5% of cases.²⁾ When faced with such displacement, many interventionists resort to rescue stenting to stabilize the device and maintain patency of the parent vessel. However, stenting is associated with a substantially higher risk of thromboembolic complications, with rates reported as high as 33.3% in some series, and necessitates unanticipated, long-term DAPT.³⁾

In this report, we describe a case of post-detachment WEB displacement triggered by vascular recoil during the withdrawal of an adjunctive microcatheter. We demonstrate that mechanical manipulation using a microcatheter (the “pushing technique”) can serve as a feasible alternative bailout strategy to restore vessel flow, preserving the inherent benefits of the WEB device while avoiding the morbidity associated with rescue stenting.

Case Presentation

A 42-year-old male with no significant medical history was referred to our institution for the management of an unruptured left middle cerebral artery (MCA) bifurcation aneurysm (Fig. 1A). Subsequent follow-up imaging demonstrated aneurysm enlargement, with dimensions measuring 4.50 mm in dome diameter, 3.72 mm in height, and a neck width of 4.17 mm. The aneurysm was a wide-neck bifurcation type, riding on the inferior trunk of the MCA bifurcation (Fig. 1B). Preoperative slab maximum intensity projection clearly visualized the spatial relationship between the aneurysm neck and the origin of the M2 inferior trunk (Fig. 1C).

Fig. 1. Preoperative planning and clinical reasoning for device sizing. (A) MRA providing an overall view of the aneurysm. (B) Linear measurements of the dome and neck. (C) slab-MIP reconstructed at the working angle, clarifying the spatial relationship between the aneurysm and the M2 inferior trunk. (D) Volumetric analysis integrating 3D morphological data and volume calculation. The sizing logic was to select a 5-mm width to appropriately oversize the dome width (4.50 mm) for stability, while ensuring the device volume remained below the total aneurysm volume to prevent branch impingement.

slab-MIP, slab maximum intensity projection

To prepare for the possibility of rescue stenting in this complex bifurcation anatomy, the patient was premedicated with DAPT (aspirin 100 mg and prasugrel 3.75 mg daily) prior to the procedure. Adequate platelet inhibition was verified using point-of-care testing (VerifyNow; Accumetrics, San Diego, CA, USA) and light transmission aggregometry. The procedure was performed under general anesthesia via a right radial approach. A 5.5-Fr Axcelguide Radix (Medikit, Tokyo, Japan) was inserted into the right radial artery and navigated to the left internal carotid artery. Precise anatomical assessment was conducted using high-resolution 3D DSA on a Siemens ARTIS icono biplane (ARTIS icono VE20 software; Siemens Healthineers, Erlangen, Germany). Volumetric analysis was conducted on a syngo X Workplace using the “syngo Aneurysm Analysis” software (both Siemens Healthineers, Erlangen, Germany) to aid in selecting the best device based on high-precision 3D rotational angiogram data (Fig. 1D). The aneurysm volume was estimated to be approximately 70.4 mm³. To prepare for potential rescue stenting in complex anatomy, an SL-10 microcatheter (Stryker, Kalamazoo, MI, USA) was pre-positioned in the inferior trunk as a safety access to the branch, which also served to temporarily stabilize the acute angulation of the parent artery.

The device selection was strategically planned to balance anchoring stability with branch safety. We selected a WEB SL 5 × 3 mm (Terumo Neuro); the 5 mm width was chosen to appropriately oversize the dome width (4.50 mm) to ensure stable wall-to-wall apposition, while the predicted device volume (approximately 59 mm³) was intentionally kept smaller than the aneurysm volume (70.4 mm³) to prevent over-projection and subsequent occlusion of the adjacent M2 inferior trunk.

A WEB SL 5 × 3 mm device was deployed based on an integrated assessment of linear and volumetric data, using a Leonis Mova microcatheter, standard type (SB-Kawasumi Laboratories, Kanagawa, Japan), which has a 0.021-inch inner diameter compatible with the WEB 21 system. The Leonis Mova microcatheter was selected because of a slight axial mismatch between the parent vessel and the aneurysm; its excellent tip shapeability and maneuverability enabled precise manual control of the microcatheter tip orientation during deployment, ensuring stable coaxial alignment, as recently reported by Kuramoto et al.⁴⁾

Intraoperative fluoroscopy confirmed optimal wall-to-wall apposition upon initial deployment (Fig. 2A), and the device was detached (Fig. 2B). However, upon withdrawing the SL-10 microcatheter from the inferior trunk, the bifurcation underwent elastic recoil, restoring its original acute angulation and causing immediate flow compromise. This mechanical shift caused the recently detached WEB device to rotate and protrude toward the orifice of the inferior trunk, resulting in poor visualization of the vessel and compromised distal flow (Fig. 2C and 2D).

Fig. 2. Technical complication: The vascular recoil mechanism. (A) Initial deployment showing optimal wall-to-wall apposition. (B) Status immediately post-detachment, appearing stable. (C) The trigger: Withdrawal of the adjunctive SL-10 microcatheter from the inferior trunk triggers vascular recoil of the bifurcation anatomy, restoring its original acute angulation and causing immediate flow compromise. (D) slab-MIP confirming the protrusion of the detached device into the inferior trunk (arrow) as a direct consequence of this mechanical shift.

SL-10, Stryker, Kalamazoo, MI, USA; slab-MIP, slab maximum intensity projection

To address this dislocation, we first attempted to push the device using a CHIKAI Nexus 14 microguidewire (Asahi Intecc, Aichi, Japan). The tip of the microguidewire was slightly curved to push the proximal surface of the WEB device. This manipulation resulted in a nearly 90° rotation of the device within the sac (Fig. 3A). Subsequently, a Leonis Mova microcatheter was introduced without tip shaping and utilized to further push the proximal marker, successfully reseating the WEB entirely within the aneurysm sac (Fig. 3B). Immediate angiography confirmed the restoration of flow in the inferior trunk (Fig. 3C and 3D). The final angiography run verified stable device seating and complete branch preservation.

Fig. 3. Sequential rescue via the “pushing technique.” (A) Stage 1: Manipulation using a microguidewire to pivot the dislocated device (nearly 90° rotation) to clear the branch orifice. (B) Stage 2: Using the Leonis Mova microcatheter tip to apply controlled force, firmly seating the device back into the sac. (C) Final DSA and (D) slab-MIP, reconstructed at the identical working angle as Fig. 1C, confirming complete restoration of flow in the inferior trunk and stable intrasaccular position.

Leonis Mova, SB-Kawasumi Laboratories, Kanagawa, Japan; slab-MIP, slab maximum intensity projection

Postoperative recovery was uneventful. MRI on postoperative day 1 showed only minor, asymptomatic embolic foci. The patient was discharged on postoperative day 4 on single antiplatelet therapy and has remained neurologically intact at follow-up. Written informed consent was obtained from the patient for the publication of this case report and any accompanying images.

Discussion

The primary trigger for device displacement in this case was vascular recoil during withdrawal of the adjunctive microcatheter. A previous multicenter study reported that an abrupt change in WEB device (Terumo Neuro) orientation immediately following detachment occurs in approximately 4.5% of cases.²⁾ This position change was frequently necessitated by acute angulation of the parent artery. In our case, the pre-positioned microcatheter acted as a “stiffener,” temporarily straightening the acute bifurcation angle of the MCA. Upon its withdrawal, the parent artery underwent elastic recoil to its original morphology. During this rapid geometric shift, the detached WEB was subjected to mechanical force, causing it to pivot and protrude toward the orifice of the inferior trunk. This highlights a critical “transition phase” in the procedure; operators must maintain extreme vigilance when removing adjunctive tools even after a seemingly stable detachment. As a preventive measure, leaving a microguidewire temporarily in the branch during the microcatheter withdrawal can act as a safety mechanism, allowing the operator to assess vascular recoil, device stability, and branch patency before committing to final tool removal.

This displacement occurred despite pre-procedural planning using the Siemens ARTIS icono biplane system (ARTIS icono VE20 software; Siemens Healthineers) and automated volumetric analysis. We selected a 5 × 3 mm WEB device based on the “+1/−1 rule”⁵⁾ and volumetric parameters, including the device-aneurysm volume ratio⁶⁾ and the ideal WEB-aneurysm volume ratio.⁷⁾ Although these parameters are useful, they cannot fully account for dynamic mechanical interactions, such as the vascular recoil experienced during the withdrawal of adjunctive tools. Technical complications, including device displacement, remain inherent risks in WEB embolization.⁸⁾ Specifically, the adjunctive use of stents or flow diverters was required in 3.1% of aneurysms (5/159) in a cumulative series due to WEB protrusion or an unmanageable wide neck, demonstrating that technical events requiring additional devices remain inherently unavoidable.⁹⁾ Our experience demonstrates that static pre-operative measurements, regardless of precision, cannot fully account for the dynamic mechanical interactions, such as the vascular recoil experienced upon the withdrawal of adjunctive tools.

When faced with post-detachment displacement, rescue stenting is the standard and most established bailout strategy.³⁾ However, stenting is associated with an increased risk of thromboembolic complications and necessitates unplanned long-term DAPT. Gravino et al. and John et al. have emphasized the importance of knowing the available “armamentarium” for managing such complications, including the use of microcatheters.^10,11) By leveraging the inherent axial stability and distal support of the microcatheter (e.g., the Leonis Mova; SB-Kawasumi Laboratories), the operator can physically reseat the device, potentially avoiding more invasive maneuvers such as rescue stenting or the extreme measures required for “WEBectomy” (endovascular retrieval).^12,13) This case demonstrates that microcatheter manipulation (the “pushing technique”) can be a feasible alternative bailout option in selected circumstances where rescue stenting is deemed unsuitable or high-risk. Nevertheless, this technique is not without significant risks. Potential complications include aneurysm perforation by the microguidewire or microcatheter, mechanical damage to the WEB mesh (which may lead to device compaction or impaired flow disruption), thromboembolism due to prolonged intraoperative manipulation, and the risk of inadvertent vessel occlusion. Furthermore, the applicability of this “pushing technique” depends heavily on the degree of axis deviation between the parent artery and the protruded WEB device. In cases with marked axis deviation, mechanical manipulation may fail to appropriately align the device with the aneurysm neck and instead pose a high risk of vessel injury. Therefore, careful patient selection and intraoperative anatomical assessment are imperative. Operators must recognize that this maneuver is an exceptional measure and should be attempted only when the anticipated benefits outweigh these substantial iatrogenic risks. In the present case, the patient was fully prepared for rescue stenting with effective preoperative DAPT. However, the primary rationale for selecting the WEB device for this 42-year-old patient was to avoid a permanent endoluminal implant and circumvent the necessity for mandatory long-term DAPT, thereby minimizing lifelong bleeding risks. While rescue stenting was immediately available as a standard bailout, deploying a stent would have definitively committed the patient to long-term DAPT, negating the primary advantage of the WEB device. Therefore, we adopted a stepwise approach: an initial attempt to physically reseat the device via microcatheter manipulation, holding rescue stenting in immediate reserve should the manipulation fail or pose excessive risk. We believe this stepwise strategy is clinically acceptable to preserve the low-profile benefits of the WEB in young patients, provided that the operators are fully prepared to proceed to stenting if required.

Regarding the choice of microcatheter for this maneuver, the “pushing technique” was successfully performed using the Leonis Mova in this case. The trackability and maneuverability of the Leonis Mova allowed for precise control and the transmission of mechanical force required to reseat the device during the rescue maneuver.

In this case, the final repositioning resulted in a 90° rotation of the WEB. While the device base is specifically engineered with maximum wire density at the poles to optimize flow disruption, the lateral nitinol mesh also provides structural coverage. Goyal et al. emphasized that obtaining significant compression of the device is critical to its flow-disruption function.⁵⁾ In our case, the device achieved adequate wall-to-wall apposition and compression, which we prioritized over pursuing a perfect “base-on” orientation to immediately restore parent vessel patency and avoid the morbidity associated with unanticipated rescue stenting.³⁾ Given the stability of the device and the restoration of flow, we deemed this 90° orientation a clinically acceptable result to minimize iatrogenic risk while potentially preserving enough flow modification to facilitate eventual thrombosis.

Finally, a significant limitation of this report is its nature as a single case study with limited follow-up. While the “pushing technique” successfully restored parent vessel patency, the long-term efficacy and the risk of device compaction or recanalization for a WEB in a 90° rotated position have not been established. Further accumulation of clinical experience and long-term radiological follow-up are necessary to validate the durability of this rescue maneuver.

Conclusion

Post-detachment displacement is an unpredictable risk in WEB (Terumo Neuro) embolization that can occur despite volumetric planning. Our experience demonstrates that mechanical manipulation with a microcatheter “pushing technique” is a feasible alternative bailout option in selected circumstances. This approach restores parent vessel patency and ensures stable device seating while preserving the WEB device’s low-profile advantages and avoiding the substantial risks associated with rescue stenting and long-term DAPT. Mastering this maneuver is essential for neurointerventionists to manage the dynamic transition phases inherent in complex intracranial aneurysm therapy.

Disclosure statement

Shinichi Yoshimura has received lecture fees from Stryker, Medtronic, Johnson & Johnson, Kaneka Medics, and Terumo. The other authors have no conflicts of interest.