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Stent-assisted coiling for aneurysms and the phenomenon of stent migration: is it worth it?
  1. Charles J Prestigiacomo
  1. Correspondence to Dr Charles J Prestigiacomo, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 90 Bergen St, Suite 8100, Newark, NJ 07101, USA; c.pretigiacomo{at}umdnj.edu

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The Journal of NeuroInterventional Surgery is publishing two case reports that describe very similar events in the endovascular treatment of aneurysms. Pan et al and Dashti et al join the published literature of six additional case reports that describe the spontaneous, clearly unplanned, proximal migration of a stent deployed for the treatment of a wide-necked aneurysm (see pages 352 and 356).1–7 The reader may wonder why such attention is being paid for what might be considered a relatively low incidence of this unexpected event with seemingly minimal (though undeniable) clinical events. There are several reasons for this.

The first reason would simply be that of safety. Does the fact that there are anecdotal reports describing a similar event imply that the use or placement of this stent is “unsafe” in the posterior circulation? In my opinion, that is certainly not the case. Rather, in fields such as ours that continue to grow at a tremendous rate, and where technological advances are developed and improved by direct interactions between the practicing physicians and the engineers, such information needs to be presented, evaluated, and discussed objectively. It would be of great interest to the readership if all NeuroInterventionalists experienced in the use of this specific stent would review their population of patients and present details of whether similar events have occurred and also if they have not. In other words, the eight published case reports do not describe the true incidence of this event as we are unaware of the number of times the stent was placed in similar circumstances without any adverse sequelae. Consequently, safety of this stent in the aforementioned setting is not something that can be discussed objectively at this time.

The second reason for similar reports is that of understanding. Each of the authors presents a concise delineation of the events and a possible mechanism of explanation for the event. In all cases, the reports suggest that a vessel mismatch between the distal and proximal vasculature, along with the stent's closed-cell design and its 4.5 mm diameter, contributes to the retrograde (or proximal) migration of the stent over time. Having reviewed the individual case reports, an additional consideration to explain the “watermelon seed” effect would be to better assess the relative angulation of the posterior cerebral arteries relative to the long axis of the basilar artery. One would imagine a significant increase in strain and stress placed on the entire stent system through its struts if additional “angular load” is added to the system. This might seem obvious in the setting of cranial fusion of the basilar artery where the posterior cerebral arteries branch nearly orthogonal to the basilar artery in the coronal plane. How can this apply to the setting of basilar arteries that exhibit caudal fusion and thus, a “gentler” angulation of the origins of the posterior cerebral artery (PCA) as noted in some of the reports?4 5 Careful evaluation of the published images would suggest that in that setting, the “angular load” is in the sagittal plane as the PCA may begin its sharp course around the midbrain along three dimensions simultaneously.

The final reason for presenting these case reports is that of improvement. The field of NeuroInterventional surgery will continue to grow and mature on the shoulders of those who have come before and of those who are to follow. Openly presenting, studying, and discussing these events will only help us better understand the nuances of using the numerous devices in our armamentarium as well as discuss ways to improve them. For instance, the benefits of closed-cell designs and open-cell designs are numerous and distinct. Perhaps consideration should be made for tapered stent designs? Perhaps there should be consideration for a ‘near-closed-cell’ design or ‘partial-open-cell’ design. It is incumbent on us to continue to work closely and creatively with colleagues and industry to keep “raising the bar” in providing safe, effective therapy for patients.

Can this be achieved? Does the current environment make this possible? Though there may be several hurdles in our midst, not the least of which are conflict of interest and cost, an open, transparent reporting of these interactions should certainly not prohibit them.

Is it worth it? Is it worth taking the time to read these reports that describe a similar phenomenon? Is it worth reviewing our data to see what the ‘true’ incidence of this phenomenon is? Is it worth thinking about the various other likely reasons for this unexpected event to occur? Is it worth taking the time to ‘brainstorm’ as a community to come together and think of modifications for this and other technologies that are being used at the edge of indications as we continue to push the edges of the envelope in the treatment of cerebrovascular disease and thus redefine that very same envelope? I cannot imagine that the field would be where it is today if others before us had not said ‘Yes’.

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Footnotes

  • Competing interests None.

  • Provenance and peer review Not commissioned; not externally peer reviewed.

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