- Department of Neurosurgery, Kurashiki Central Hospital, Okayama, Japan
Correspondence Address:
Natsuki Akaike, Department of Neurosurgery, Kurashiki Central Hospital, Okayama, Japan.
DOI:10.25259/SNI_366_2025
Copyright: © 2025 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.How to cite this article: Natsuki Akaike, Hiroyuki Ikeda, Mai Tanimura, Minami Uezato, Masanori Kinosada, Yoshitaka Kurosaki, Masaki Chin. Sticking after detachment procedure of coil with floating detachment link with ball joint due to excessively bent junction: A case report and a bench-top experiment. 13-Jun-2025;16:244
How to cite this URL: Natsuki Akaike, Hiroyuki Ikeda, Mai Tanimura, Minami Uezato, Masanori Kinosada, Yoshitaka Kurosaki, Masaki Chin. Sticking after detachment procedure of coil with floating detachment link with ball joint due to excessively bent junction: A case report and a bench-top experiment. 13-Jun-2025;16:244. Available from: https://surgicalneurologyint.com/?post_type=surgicalint_articles&p=13623
Abstract
Background: We present a case of coil sticking, likely caused by an excessively bent junction of the coil and the delivery pusher, with a bench-top experiment to determine the cause of coil sticking in this case.
Case Description: A coil embolization procedure was performed for an internal carotid artery aneurysm. During the framing with the Axium Prime Frame coil, the tip of the microcatheter was advanced to the center of the coil mass within the aneurysm to insert the coil. After detachment, the coil became stuck. Pulling the delivery pusher allowed the coil to detach from the delivery pusher within the microcatheter. After flushing the microcatheter with heparinized saline, the proximal end of the coil fortuitously settled within the aneurysm and the procedure was concluded without complications. A bench-top experiment suggested that an excessively bent junction of the coil and the delivery pusher causes the ball joint of the floating detachment link to hook into the circular opening.
Conclusion: When using coils with a floating detachment link that has a ball joint, forcibly advancing the microcatheter while the tip of the microcatheter is aligned with the junction may cause excessive bending of the junction, resulting in coil sticking.
Keywords: Axium coil, Coil sticking, Detachment, Embolization
INTRODUCTION
Coil-related problems such as sticking, knotting, fracturing, and unraveling have been reported during coil embolization of cerebral aneurysms.[
CASE REPORT
History and examination
A 79-year-old woman underwent emergency coil embolization under general anesthesia for a ruptured left internal carotid-posterior communicating artery aneurysm. After systemic heparinization, a 6-Fr Fubuki dilator kit (Asahi Intecc, Seto, Japan) was inserted through the right femoral artery and placed in the left cervical internal carotid artery. Cerebral angiography revealed a left internal carotid-posterior communicating artery aneurysm (neck: 2.7 mm, dome: 3.8 × 3.9 mm, height: 4.4 mm) [
Figure 1:
Imaging findings from coil embolization (working angle, frontal view): (a) Pretreatment cerebral angiogram. (b) Pretreatment three-dimensional cerebral angiogram. (c) The Phenom 17 is positioned at the neck of the aneurysm (white arrow) and the coil is inserted into the aneurysm. The black arrow shows the second marker on the Phenom 17. (d) The tip of the Phenom 17 is advanced to the center of the aneurysm (white arrow) and the second marker on the Phenom 17 is advanced farther (black arrow). The alignment marker on the delivery pusher and the second marker on the Phenom 17 form an inverted T-shape. (e) Pulling the delivery pusher back into the Phenom 17 causes the coil to follow the delivery pusher (black arrowhead). (f) The coil detaches from the delivery pusher and the recoil causes the coil to advance (black arrowhead). (g) After the coil detachment, flushing the Phenom 17 with heparinized saline advances the coil into the aneurysm. (h) Post-treatment cerebral angiogram showing the residual neck of the aneurysm.
Bench-top experiment
Medtronic provided all Axium Prime coils and microcatheters free of charge for research purposes. All experiments were performed by a single operator (NA) with 6 years of clinical experience.
When the delivery pusher of a new Axium coil was fixed to the tabletop and the slide knob of the instant detacher was pulled, the proximal end of the coil detached from the delivery pusher [
Figure 2:
Bench-top experiment using Axium coil: (a) a new Axium coil fixed to the tabletop. The delivery pusher (black bidirectional arrow) and the proximal end of the coil (white bidirectional arrow) are linearly engaged at the junction (black arrow). (b) With a straight junction, the proximal end of the coil immediately detaches from the delivery pusher in a detachment process. (c) The floating detachment link is not visible at the proximal end of the coil after detachment (black arrowhead). (d) The ball joint of the floating detachment link removed from the proximal end of the coil is straight. (e) A new Axium coil fixed to the tabletop with an excessively bent junction (white arrow). (f) The delivery pusher and the proximal end of the coil remain engaged after a detachment attempt. (g) After detachment, the floating detachment link is not retracted into the coil and remains visible at the proximal end of the coil (white arrowhead). (h) The ball joint of the floating detachment link removed from the proximal end of the coil is bent.
When the delivery pusher of a new Axium coil was fixed to the tabletop and the junction was excessively bent [
A Phenom 17 was placed within an aneurysm model made of silicone and an Axium coil was inserted through the Phenom 17. The tip of the Phenom 17 was aligned with the junction and was compressed against the aneurysm wall, resulting in an excessively bent junction [
Figure 3:
Bench-top experiment using aneurysm model: (a) Silicone aneurysm with Axium coil inserted through Phenom 17. The tip of the Phenom 17 is aligned with the junction (rectangle). The tip of the Phenom 17 tip is compressed against the aneurysm wall, resulting in an excessively bent junction. (b) Magnified view of the rectangle area in Figure 3a. (c) After a detachment attempt, the delivery pusher and the proximal end of the coil remain engaged. (d) Pulling the delivery pusher releases the engagement, and the coil detaches from the delivery pusher. The floating detachment link is not retracted into the coil and remains visible at the proximal end of the coil (white arrowhead). (e) The ball joint of the floating detachment link removed from the proximal end of the coil is bent.
Patient informed consent
The necessary patient informed consent was obtained in this study.
DISCUSSION
This case is a rare instance of coil-related complications similar to unraveling and knotting. This is the first report to elucidate the mechanism of coil sticking based on intraoperative imaging findings and bench-top experiments, which appears to be caused by an excessively bent junction of the coil and the delivery pusher.
The Axium coil is a mechanically detachable coil. According to the manufacturing data, it has a floating detachment link with a ball joint [
Figure 4:
Diagram of coil sticking mechanism: The tip of the delivery pusher tip (left) and the proximal end of the coil (right). (a) Axium coil before detachment. The floating detachment link has a ball joint (*) whose diameter (white bidirectional arrow) is slightly smaller than the diameter of the circular opening (red bidirectional arrow). A release wire (black arrow) located in the circular opening holds the ball joint in place. (b) Axium coil after detachment. The release wire is retracted into the delivery pusher and the ball joint of the floating detachment link detaches from the circular ring. The floating detachment link is then retracted into the proximal end of the coil. (c) Axium coil in this case before the detachment attempt. The ball joint of the floating detachment link is bent. (d) Axium coil in this case after the detachment attempt. The ball joint of the floating detachment link hooks into the circular opening, preventing the proximal end of the coil from disengaging from the delivery pusher.
Coil sticking within the microcatheter usually occurs when the tip of the delivery pusher and the proximal end of the coil overlap and engage within the microcatheter.[
The mechanism of coil sticking in this case appears to be specific to the Axium coil that has a floating detachment link with a ball joint. When using Axium coils, the microcatheter tip against should not be pressed against the coil mass, as alignment with the junction may cause excessive bending of the junction. During the initial and final stages of coil insertion, the position of the second marker on the microcatheter should be monitored to ensure that the microcatheter is not advanced too far into the aneurysm. In this case, when the coil was suspected of being stuck, the coil retrieved by pulling the delivery pusher and the coil unexpectedly detached from the circular opening and became dislodged within the microcatheter. After retraction of the delivery pusher, flushing the microcatheter with heparinized saline was performed under non-fluoroscopic guidance. Subsequent fluoroscopy showed that the dislodged coil had settled within the aneurysm. In this case, the aneurysm neck was relatively narrow and the coil was inserted into the aneurysm by simply advancing it. The length of coil withdrawn from the aneurysm was 2 cm and most of the coil (6 cm) remained within the aneurysm. We therefore gently pushed the coil into the aneurysm with a microguidewire so that the coil could be advanced but not retracted into the microcatheter. If the shape of the aneurysm allows for simple advancement of a short coil into the aneurysm, pushing the coil with a microguidewire is considered a good approach; if the shape of the aneurysm shape does not allow for simple advancement of the coil or if the coil is relatively long, it is better to retrieve the coil. In such a case, applying suction to the microcatheter and gently pulling the microcatheter and coil together may hold them together. If the coil does not fully settle within the aneurysm and prolapses into the parent vessel, ischemic complications may occur.[
CONCLUSION
When using coils with a floating detachment link that has a ball joint, forcibly advancing the microcatheter while the tip of the microcatheter is aligned with the junction may cause excessive bending of the junction, resulting in coil sticking.
Ethical approval:
The Institutional Review Board approval is not required.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent
Financial support and sponsorship:
Nil.
Conflicts of interest:
Dr. Ikeda reports lecturer’s fees from Medtronic, DaiichiSankyo, Johnson and Johnson, Terumo, Stryker Japan.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Disclaimer
The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.
Acknowledgments:
We would like to thank Ms. Miho Kobayashi for the English language review.
References
1. Abdelrady MM, Ognard J, Abdelsamad AM, Mahmoud M. Parent artery stenting as a rescue management for stretched coils during cerebral aneurysms embolization: Report of three cases and review of literature. Interv Neuroradiol. 2022. 28: 613-22
2. Abdihalim M, Kim SH, Maud A, Suri MF, Tariq N, Qureshi AI. Short-and intermediate-term angiographic and clinical outcomes of patients with various grades of coil protrusions following embolization of intracranial aneurysms. AJNR Am J Neuroradiol. 2011. 32: 1392-8
3. Abe T, Hirohata M, Tanaka N, Uchiyama Y, Morimitsu H, Kojima K. Coil migration, malposition, stretching and retrieval. Interv Neuroradiol. 2000. 6: 143-7
4. Dinc H, Kuzeyli K, Kosucu P, Sari A, Cekirge S. Retrieval of prolapsed coils during endovascular treatment of cerebral aneurysms. Neuroradiology. 2006. 48: 269-72
5. Ding D, Liu KC. Management strategies for intraprocedural coil migration during endovascular treatment of intracranial aneurysms. J Neurointerv Surg. 2014. 6: 428-31
6. Fiorella D, Albuquerque FC, Deshmukh VR, McDougall CG. Monorail snare technique for the recovery of stretched platinum coils: Technical case report. Neurosurgery. 2005. 57: E210
7. Henkes H, Fischer S, Weber W, Miloslavski E, Felber S, Brew S. Endovascular coil occlusion of 1811 intracranial aneurysms: Early angiographic and clinical results. Neurosurgery. 2004. 54: 268-80
8. Henkes H, Lowens S, Preiss H, Reinartz J, Miloslavski E, Kühne D. A new device for endovascular coil retrieval from intracranial vessels: Alligator retrieval device. AJNR Am J Neuroradiol. 2006. 27: 327-9
9. Kwon OK, Lee KJ, Han MH, Ko YC. Coil breakage during aneurysm embolization. Case report. Interv Neuroradiol. 2002. 8: 21-3
10. Kwon SC, Lyo IU, Shin SH, Park JB, Kim Y. Coil knotting during endovascular coil embolization for ruptured MCA aneurysm. A case report. Interv Neuroradiol. 2008. 14: 331-4
11. Lee CY. Use of wire as a snare for endovascular retrieval of displaced or stretched coils: Rescue from a technical complication. Neuroradiology. 2011. 53: 31-5
12. Luo CB, Chang FC, Teng MM, Guo WY, Chang CY. Stent management of coil herniation in embolization of internal carotid aneurysms. AJNR Am J Neuroradiol. 2008. 29: 1951-5
13. Standard SC, Chavis TD, Wakhloo AK, Ahuja A, Guterman LR, Hopkins LN. Retrieval of a Guglielmi detachable coil after unraveling and fracture: Case report and experimental results. Neurosurgery. 1994. 35: 994-8
14. Torikoshi S, Ikeda H, Otsuka R, Tsujimoto Y, Sano N, Hayase M. Case of a stuck coil in the final stage of stent-assisted coil embolization. J Neuroendovasc Ther. 2021. 15: 659-64
15. Yonaha H, Hyodo A, Inaji T, Ito K, Kushi S, Tsuchida K. Thromboembolic events associated with coil protrusion into parent arteries after GDC treatment. Interv Neuroradiol. 2006. 12: 105-11