Hydrophilic polymer embolic complication during diagnostic cerebral angiography presenting with delayed intracranial hemorrhage: case report and literature review

Fragmentation of Hydrophilic Guidewire Coatings During Neuroendovascular Therapy

PURPOSE

Cerebral polymer coating embolism from intravascular devices may cause serious complications after endovascular therapy (EVT) for neurovascular diseases. Although polymer fragments are often created during endovascular procedures, exact mechanisms of their formation, especially if of small size, are largely unknown.

METHODS

In this study eight microguidewires (Asahi Chikai 200 cm (Asahi Intecc, Aichi, Japan), Asahi Chikai Black (Asahi Intecc), Fathom™ (Boston Scientific, Marlborough, MA, USA), Hybrid (Balt Extrusion, Montmorency, France), Radifocus® Guide Wire GT (Terumo, Leuven, Belgium), Synchro2® (Stryker, Kalamazoo, MI, USA), Transend™ EX (Boston Scientific), and Traxcess™ (MicroVention®, Tustin, CA, USA)) frequently used during EVT were investigated ex vivo using their dedicated metal or plastic insertion tools to assess for coating delamination after backloading of the microguidewires.

RESULTS

Backloading caused damage to the coating of all microguidewires especially when the main body of the guidewires was bent in front of the insertion tool. All studied microguidewires produced microscopic filamentous and/or band-like coating fragments. Few larger irregular fragments were observed, but also very small fragments measuring 1-3 µm in diameter were found. Spectroscopic measurements of polymer fragments and microguidewires identified various polymers.

CONCLUSION

Backloading of polymer-coated microguidewires during EVT should be minimized if possible. More stable hydrophilic coatings on microguidewires and less traumatic insertion tools are desirable.

Comaneci stent-angioplasty for the optimization of inadequately deployed flow diverter stents

BACKGROUND AND PURPOSE

In endovascular procedures, inadequate deployment of a flow diverter stent is a highly concerning technical complication that can lead to acute parent vessel occlusion and ischaemic events. This study aimed to assess the off-label use of the Comaneci device in managing technical difficulties associated with flow diversion.

MATERIALS AND METHODS

We conducted an analysis of all flow diverter procedures documented in our prospectively collected database. Our objective was to identify patients with inadequately deployed implants who underwent Comaneci stent-angioplasty. Both Comaneci 17 and Comaneci 21 devices were utilized to address and remediate technical complications related to stent deployment. We reviewed anatomical features, technical details, intraprocedural complications, as well as clinical and angiographic outcomes.

RESULTS

Thirty-one Comaneci devices were employed to remediate 31 inadequately deployed flow diverter stents. Successful resolution of technical complications associated with flow diverter placement was achieved in all attempted cases. No clinically significant complications were attributed to the technique, and no mortality was observed during the study.

CONCLUSION

Technical issues arising from flow diverter stent deployment are formidable complications. Familiarity with appropriate corrective manoeuvres is essential to achieve successful outcomes. The Comaneci device can be safely and effectively incorporated into the range of techniques used to rectify inadequately deployed stents.

Polytetrafluoroethylene coating fragments during neuroendovascular therapy: An analysis of two damaged microguidewires

Cerebral polymer coating embolism from intravascular devices represents a potentially serious complication to endovascular therapy (EVT). We report two cases of neuroendovascular treatment where filamentous polymer fragments were noted possibly due to damage of the surface coating during manipulation and backloading of microguidewires. As the exact origin of the debris was initially not known, microguidewires and fragments were examined with light microscopy, stereomicroscopy, scanning electron microscopy and attenuated-total-reflection Fourier transform infrared spectroscopy. Fragments consisted of polytetrafluoroethylene and silicone oil stemming from the proximal shaft of a standard microguidewire. To our knowledge, this is the first report of polytetrafluoroethylene coating fragments created during EVT. Future studies should assess the mechanism of polymer coating delamination and its potential consequences during EVT including inadvertent fragment migration into the cerebral circulation.

Medical treatment of polymeric cerebral granulomatous reactions following endovascular procedures

BACKGROUND

Endovascular procedures are standard of care for an increasing range of cerebrovascular diseases. Many endovascular devices contain plastic and are coated with a hydrophilic polymer which has been rarely described to embolize, resulting in distal granulomatous inflammatory lesions within the vascular territory.

METHODS

We reviewed three cases of cerebral granulomatous reactions that occurred after endovascular intervention for internal carotid aneurysms. The patient procedure details, presentation, relevant investigations, and treatment course are described. We also provide a literature review on endovascular granulomatous reactions.

RESULTS

These three cases represent the largest biopsy proven series of cerebral granulomatosis following endovascular intervention. We highlight the variable clinical presentation, with two of the three cases having an unusually delayed onset of up to 4 years following the intervention. We show the characteristic histological findings of granulomatous lesions with foreign body material consistent with a type IV reaction, radiological abnormalities of enhancing lesions within the vascular territory of the intervention, and the requirement of prolonged immunosuppression for maintenance of clinical remission, with two of the three patients requiring a corticosteroid sparing agent. In comparison with the available literature, in addition to hydrophilic gel polymer, we discuss that plastic from the lining of the envoy catheter may be a source of embolic material. We also discuss the recommendations of the Food and Drug Administration and the implementation of novel biomaterials for the prevention of these reactions in the future.

CONCLUSIONS

There is a need for increased awareness of this severe complication of cerebral endovascular procedures and further longitudinal studies of its prevalence, optimal management and preventative measures.

Suspected Metallic Embolization Distal to Coiled Intracranial Aneurysms Detectable by Susceptibility-Weighted MR Imaging

BACKGROUND AND PURPOSE

After endovascular coiling of intracranial aneurysms, round dark parenchymal lesions believed to be particulate metal are sometimes encountered in MR imaging studies of the brain. We used SWI to assess the frequency of such occurrences, in addition to exploring likely causes and clinical implications.

MATERIALS AND METHODS

We reviewed 700 MR imaging studies performed between September 2018 and March 2019 at our institution as follow-up monitoring of coiled intracranial aneurysms. Any sizeable (>5 mm) rounded dark-signal lesions encountered were presumed to be metallic. The magnitudes and locations of such lesions were recorded. In patients with these lesions, pertinent procedural documentation was screened for devices used, including coils, microcatheters, microguidewires, and stents. Medical records were also examined to determine whether any related symptoms ensued.

RESULTS

Twenty patients (2.8%) exhibited a total of 25 lesions on SWI. Diameters ranged from 5 to 11 mm (median, 8 mm). All except 2 lesions were located in brain regions downstream from aneurysms, but all lesions occupied vascular territories of vessels used to place guiding catheters. Other than the Synchro 14, which was routinely deployed, no device was regularly used in patients with SWI-detectable lesions; and none of the affected patients developed focal neurologic symptoms as a consequence.

CONCLUSIONS

Although the origins remain unclear, distal embolization of particulate metal distal to coiled cerebral aneurysms is occasionally observed on follow-up MR imaging studies. Such lesions, however, seem to have no apparent clinical impact.

Delayed Leukoencephalopathy: A Rare Complication after Coiling of Cerebral Aneurysms

BACKGROUND AND PURPOSE

Delayed leukoencephalopathy is a rare complication that occurs after endovascular coiling of cerebral aneurysms. We aimed to describe a clinical picture of delayed leukoencephalopathy and explore potential associations with procedural characteristics.

MATERIALS AND METHODS

We considered endovascular coiling procedures for cerebral aneurysms performed between January 2006 and December 2017 in our institution with follow-up MRIs. We used logistic regression models to estimate the ORs of delayed leukoencephalopathy for each procedural characteristic.

RESULTS

We reviewed 1754 endovascular coiling procedures of 1594 aneurysms. Sixteen of 1722 (0.9%) procedures demonstrated delayed leukoencephalopathy on follow-up FLAIR MR imaging examinations after a median period of 71.5 days (interquartile range, 30-101 days) in the form of high-signal changes in the white matter at locations remote from the coil mass. Seven patients had headaches or hemiparesis, and 9 patients were asymptomatic. All imaging-associated changes improved subsequently. We found indications suggesting an association between delayed leukoencephalopathy and the number of microcatheters used per procedure (P = .009), along with indications suggesting that these procedures required larger median volumes of contrast medium (225 versus 175 mL, OR = 5.5, P = .008) as well as a longer median fluoroscopy duration (123.6 versus 99.3 minutes, OR = 3.0, P = .06). Our data did not suggest that delayed leukoencephalopathy was associated with the number of coils (P = .57), microguidewires (P = .35), and guiding systems (P = .57).

CONCLUSIONS

Delayed leukoencephalopathy after coiling of cerebral aneurysms may have multiple etiologies such as foreign body emboli, contrast-induced encephalopathy, or hypersensitivity reaction to foreign bodies.

Intrathrombus polymer coating deposition: a pilot study of 91 patients undergoing endovascular therapy for acute large vessel stroke. Part I: Histologic frequency

BACKGROUND

Polymer coating embolism due to vascular medical device use is an increasingly recognized iatrogenic complication. This phenomenon has been linked with various adverse effects including neuroinflammation, acute ischemic stroke, cerebral hemorrhage, and death. Notably, procedure- and device-specific risks of this complication are poorly investigated. In this study, we evaluate the detectable frequency of intra-arterial polymer coating delamination among patients who underwent endovascular thrombectomy for treatment of acute ischemic stroke due to large vessel occlusion.

METHODS

Ninety-two cerebral thrombectomy specimens were retrospectively analyzed for the presence of polymer coating particulates. Histologic findings were correlated with demographic and procedural details and patient outcomes.

RESULTS

Evidence of polymer coating deposition was found in 30 of 92 extracted thrombi (33%). No correlation between intrathrombus polymer deposition and use of a specific thrombectomy device such as a stent retriever, aspiration catheter, or guide catheter was found. However, heterogeneous patterns of device use suggest a number of culprit devices. A trend toward longer procedure times and multiple thrombectomy passes was noted in positive cases. Intrathrombus polymer deposition was not associated with adverse clinical outcomes as measured by the 90-day modified Rankin Scale (mRS); however, small sample size and follow-up intervals limit interpretation. Ninety-day outcomes based on mRS may not fully capture the clinical effects of acute and/or delayed intracerebral polymer complications.

CONCLUSION

In light of documented adverse neurologic effects, the frequency of intrathrombus polymer particulates indicates the need for consensus testing methods and large-scale long-term prospective clinical device trials, with inclusion of relevant endpoints to better assess biomaterial and device risks to patients.

Cerebral foreign body reaction due to hydrophilic polymer embolization following aneurysm treatment by pipeline flow diversion device

The use of flow diverting stents for wide based, intracranial aneurysms has become an invaluable treatment option. While intracranial hemorrhage and ischemic stroke from dislodged atherosclerotic emboli are common adverse events, the potential for delayed granulomatous inflammation from possible hydrophilic polymer emboli is rarely recognized. We present a unique case in which visible chipping of the pusher wire for stent placement was observed, followed by clinical and radiographic evidence suggestive of a delayed foreign body reaction to intracranial hydrophilic polymer emboli. A 55-year-old woman underwent placement of a Pipeline embolization device for a left-sided, broad-based aneurysm at the base of the internal carotid artery and posterior communicating artery. Two months later she developed right-sided focal neurological deficits. Imaging showed ipsilateral focal edema and enhancing lesions with contrast. Although not confirmed with biopsy and histopathology, clinical and radiographic evidence suggests that this patient probably experienced a delayed foreign body reaction to hydrophilic polymer emboli from compromised procedural equipment during flow diverting stent placement. Although previously described, this is the first instance to our knowledge in whichvisible chipping of the pusher wire was observed on a Pipeline embolization device.