Proximal migration and compaction of an Enterprise stent into a coiled basilar apex aneurysm: a posterior circulation phenomenon?

Natural history and management of posterior cerebral artery aneurysms: a systematic review and meta-analysis of individual patient data

We conducted a comprehensive review and meta-analysis to investigate clinical, radiographic characteristics, and treatment outcomes of posterior cerebral artery aneurysms (PCAA). We systematically reviewed English-language articles investigating available treatments (parent artery occlusion (PAO), microsurgery, reconstructive endovascular (rEVT), and conservative treatments) for PCAA and analyzed the based on aneurysm morphology and rupture status. Six-hundred-eighty-five patients with 698 PCAA were identified from 59 studies. Overall, 371 (54.2%) aneurysms were ruptured, 325 (49%) were saccular, and 342 (51%) were non-saccular aneurysms. The mean age of the saccular was lower (40 years) than non-saccular aneurysm group (50 years) (P < .05). In ruptured PCAA, favorable clinical outcomes were comparable between the treatment groups except for patients treated conservatively, which had lower rates of favorable clinical outcomes (35.6%) and higher mortality (55.7%) (P < .0001). Ruptured aneurysms treated with rEVT (22.6%) had the highest recanalization rates compared to PAO (9.2%, P = 0.0001) and microsurgery (3.8%, P = 0.005). In unruptured PCAA, clinical outcomes were similar; higher complication rates were noted in microsurgery (40.4%, P = 0.026) and PAO (21.5%, P = 0.015) compared to rEVT (13.2%), which had higher recanalization rates (15.6%, P < .0001). The rates of subsequent stroke following PAO were 21.8% for unruptured and 32.3% for ruptured PCAA (P = 0.078). Ruptured PCAA portend worse prognosis and typically require an intervention to achieve better outcome whereas the benefit of an intervention in unruptured PCAA is much less clear. rEVT is promising for PCAA management with a good clinical and safety profile but more recurrence compared to PAO and microsurgery.

Correlation Between Vascular Geometry Changes and Long-Term Outcomes After Enterprise Stent Deployment for Intracranial Aneurysms Located on Small Arteries

BACKGROUND

Enterprise stents are widely used for intracranial aneurysms located on small arteries (<2.5 mm in diameter) and change the geometry of parent arteries. The purpose of this study was to investigate the correlation between vascular geometry changes and long-term outcomes.

METHODS

Between May 2013 and 2018, 1065 consecutive intracranial aneurysms were treated with Enterprise stents at our institution. After inclusion and exclusion criteria were applied, 377 aneurysms with >6 months of digital subtraction angiography follow-up were evaluated. The cohort comprised 101 aneurysms located on small parent arteries. After stent-assisted coiling, the vascular geometry parameters of small parent arteries were compared to explore their correlation with procedural complications, delayed stent migration, and recanalization.

RESULTS

The rate of delayed aneurysm occlusion in patients with initial efferent artery diameter (De) <2.5 mm was significantly higher than in patients with De >2.5 mm (62.2% vs. 40.2%; P = 0.032). At follow-up, vascular geometry parameters significantly increased (P < 0.001). In multivariate analyses, larger aneurysms and initial parent artery angle (α) <90° were independent predictors of procedural complications and discrepancy in vessel size (ΔD) >0.5 mm was an independent predictor of delayed stent migration. Larger aneurysms and follow-up angle change (ΔAngle) <30° were independent predictors for recanalization of aneurysms located on small arteries.

CONCLUSIONS

Enterprise stent-assisted coiling of intracranial aneurysms located on small arteries is safe and effective. Our study found that Enterprise deployment in small arteries had a low procedural complication rate and high stent tolerance. Vascular geometry changes play an important role in aneurysm recanalization.

The Enterprise2 Stent for Endovascular Treatment of Intracranial Aneurysms: Short-Term Results From a Single Center Experience

Background: Self-expanding devices, such as the Enterprise VRD (EP-VRD) have widely used for stent-assisted coiling treatment in wided-necked aneuryms while some thromboembolic complications were reported due to its incomplete stent apposition (ISA). We report our experiences on the novel Enterprise2 (EP-VRD2) stent in vivo in the treatment of intracranial and cranial cervical junction aneurysms.

Methods: Twenty-five consecutive patients with intracranial or cranial cervical junction aneurysms were treated with EP-VRD2 stents retrospectively collected in our institution. We use the ‘jailing' technique in all cases and deployed the stent by using pushing over the outer curve technique. The 3- or 6-monthS follow-up was done regularly by DSA.

Results: Twenty-five EP-VRD2 stents were implanted to treat 21 aneurysms at the siphon segment of internal carotid artery (ICA), one at the petrous segment, two at the cervical segment, one at the verteral artery with five accompanied with stenosis. Two patients had kinking during the procedure and were solved by microwire or microcatheter massaging. Four patients with a larger arc angle and a smaller radius of the parent vessel was detected ISA. No patient underwent the ischemic event after the operation. Twenty-three of 25 patients were evaluated after 3- or 6-months by DSA, 22 showed complete occlusion (RROC1), one slight re-stenosis in the follow-up within those five patients with stenosis. A length of 23 mm seemed associated with ISA (p < 0.01).

Conclusion: The EP-VRD2 performed well in our small patient series; however, ISA could still occur with a sharp angle of the parent vessel.

Stent-assisted coiling of broad-necked intracranial aneurysms with a new braided microstent (Accero): procedural results and long-term follow-up

Intracranial stents have expanded endovascular therapy options for intracranial aneurysms. The braided Accero stent is available for clinical use since May 2015. To date, no clinical reports on the stent are available. Purpose of this study was the evaluation of the safety and efficacy of the Accero stent in stent-assisted coiling. All patients, in whom implantation of the stent was performed, were included. Primary endpoints were good clinical outcome (mRS ≤ 2) and aneurysm occlusion grades 1 and 2 (Raymond Roy Occlusion Classification). Secondary endpoints were procedural and device-related complications with permanent disability or death, complications in the course, and the recanalization rate. Between September 2015 and August 2018, thirty-four aneurysms were treated with stent-assisted coiling using the Accero. Sixteen aneurysms were untreated, four of these were ruptured. Mild neurological complications occurred in 2/34 (5.9%) treatments. Two stent occlusions occurred during follow-up. No patient had a poor procedure- or device-related outcome. After an average of 15 months of follow-up, 28/30 aneurysms were completely or near-completely occluded. The Accero stent proved to be safe and effective in the treatment of broad-based intracranial aneurysms. The complication rate and the rate of successful aneurysm occlusions are similar to those of other stents.

Endovascular Metal Devices for the Treatment of Cerebrovascular Diseases

Cerebrovascular disease involves various medical disorders that obstruct brain blood vessels or deteriorate cerebral circulation, resulting in ischemic or hemorrhagic stroke. Nowadays, platinum coils with or without biological modification have become routine embolization devices to reduce the risk of cerebral aneurysm bleeding. Additionally, many intracranial stents, flow diverters, and stent retrievers have been invented with uniquely designed structures. To accelerate the translation of these devices into clinical usage, an in-depth understanding of the mechanical and material performance of these metal-based devices is critical. However, considering the more distal location and tortuous anatomic characteristics of cerebral arteries, present devices still risk failing to arrive at target lesions. Consequently, more flexible endovascular devices and novel designs are under urgent demand to overcome the deficiencies of existing devices. Herein, the pros and cons of the current structural designs are discussed when these devices are applied to the treatment of diseases ranging broadly from hemorrhages to ischemic strokes, in order to encourage further development of such kind of devices and investigation of their use in the clinic. Moreover, novel biodegradable materials and drug elution techniques, and the design, safety, and efficacy of personalized devices for further clinical applications in cerebral vasculature are discussed.

Prolapse of the Pipeline embolization device in aneurysms: incidence, management, and outcomes

OBJECTIVE

The Pipeline embolization device (PED) is frequently used in the treatment of anterior circulation aneurysms, especially around the carotid siphon, with generally excellent results. However, the PED has its own unique technical challenges, including the occurrence of device foreshortening or migration leading to prolapse into the aneurysm. The authors sought to determine the incidence of this phenomenon, the rescue strategies, and outcomes.

METHODS

Four institutional databases of neuroendovascular procedures were reviewed for cases of intracranial aneurysms treated with PEDs. Patient and aneurysm data as well as angiographic imaging were reviewed for all cases involving device prolapse into the aneurysm.

RESULTS

A total of 413 intracranial aneurysms were treated with PEDs during the study period, by 5 neurointerventionalists. Large and giant aneurysms (≥ 2 cm) accounted for 32 of these aneurysms. Among these 32 PEDs, prolapse into the aneurysm occurred in 3 patients, with 1 of these PEDs successfully rescued and the other 2 left in situ. No patients suffered any severe complications. The 2 patients in whom the PEDs were left in situ remained on antiplatelet therapy.

CONCLUSIONS

The PED may foreshorten or migrate during or after deployment, leading to prolapse into the aneurysm. This phenomenon appears to be associated with large and giant aneurysms, vessel tortuosity, short landing zones, and use of balloon angioplasty. Future study and follow-up is needed to further evaluate this phenomenon, but some of the observations and techniques described in this paper may help to prevent or salvage prolapsed devices.

Anchoring Pipeline Flow Diverter Construct in the Treatment of Traumatic Distal Cervical Carotid Artery Injury

Background

Traumatic extracranial internal carotid artery (ICA) dissections are uncommon and can be difficult to treat. Thinning of adventitia and dilatation may occur following arterial dissection, thus resulting in a fusiform pseudoaneurysm, which can subsequently cause bleeding, expanding, or pulsatile hematoma. Currently, medical management with anticoagulation remains the first line of treatment and yields good outcomes in 75% of cases with a mortality rate of 3-4%. Endovascular intervention is indicated with failure of medical therapy, progressive enlargement of a traumatic pseudoaneurysm, acute flow-related infarcts due to vessel occlusion, or when anticoagulation is contraindicated due to risk of pseudoaneurysm rupture and hemorrhage. Recognized interventional treatments include parent artery occlusion with or without revascularization, endovascular coil embolization, and covered stenting.

Summary

A wide variety of endovascular stents are available that are capable of opening a stenosed vessel while obliterating the associated false lumen and providing a scaffold for embolization of the pseudoaneurysm. The use of the Pipeline Embolization Device (PED) in the management of traumatic intracranial pseudoaneurysms has been described. However, there are few reports on the usage of the PED for treating traumatic extracranial ICA dissection and/or pseudoaneurysms. However, a potential complication of the use of PED in the extracranial ICA is a hypothetical tendency to migrate in a mobile vessel. Thus, the risk of migration of the PED has encouraged practitioners to adopt strategies to limit this risk.

Key Messages

We describe different techniques employed to anchor the flow-diverting construct within tortuous, mobile vessels.

Republished: Novel balloon application for rescue and realignment of a proximal end migrated pipeline flex embolization device into the aneurysmal sac: complication management

The pipeline embolization device (PED) has become a routine firstline option for the treatment of an increasing population of intracranial aneurysms at many neurovascular centers. Intraprocedural complications during PED deployment, or complications associated with migration of the device, are rarely reported problems. Significant mismatch in luminal diameter between the inflow vessel and the outflow vessel or excessive dragging–stretching of the PED have been related to ‘watermelon seed’ or ‘accordion’ effects, respectively, resulting in stent migration. Here we present a novel balloon technique that was successfully used to realign an in situ flow diverting stent that had prolapsed into a large aneurysm. This represents a useful salvage technique and should be considered when encountering this potential complication.

Novel balloon application for rescue and realignment of a proximal end migrated pipeline flex embolization device into the aneurysmal sac: complication management

The pipeline embolization device (PED) has become a routine firstline option for the treatment of an increasing population of intracranial aneurysms at many neurovascular centers. Intraprocedural complications during PED deployment, or complications associated with migration of the device, are rarely reported problems. Significant mismatch in luminal diameter between the inflow vessel and the outflow vessel or excessive dragging-stretching of the PED have been related to 'watermelon seed' or 'accordion' effects, respectively, resulting in stent migration. Here we present a novel balloon technique that was successfully used to realign an in situ flow diverting stent that had prolapsed into a large aneurysm. This represents a useful salvage technique and should be considered when encountering this potential complication.

Final results of the US humanitarian device exemption study of the low-profile visualized intraluminal support (LVIS) device

Introduction

The low-profile visualized intraluminal support (LVIS) device is a new, braided, intracranial microstent designed for stent-assisted coiling.

Objective

To present the results of a single-arm, prospective, multicenter trial of the LVIS for treatment of wide-necked intracranial aneurysms.

Methods

31 patients with unruptured, wide-necked (neck ≥4 mm or dome:neck ratio ≤2) intracranial aneurysms were treated with the LVIS device and bare platinum coils at six US centers (investigational device exemption G110014). Clinical follow-up was conducted at 30 days and 6 months. Angiographic follow-up was performed at 6 months. The primary safety endpoint was any major stroke or death within 30 days or major ipsilateral stroke or neurological death within 6 months. ‘Probable benefit’ was defined as ≥90% angiographic occlusion at 6 months. An independent core laboratory adjudicated the angiographic results. An independent clinical events committee adjudicated the clinical endpoints.

Results

Average aneurysm size was 7.2 mm (SD 3.8) and average neck width was 4.6 mm (SD 1.8). 68% of patients had a dome:neck ratio ≤2. LVIS placement was technically successful in 29/31 patients (93.5%). No primary safety endpoints occurred during the study (0%). No patient had a higher modified Rankin Score at 6 months than at baseline. 26/28 (92.9%) treated aneurysms with 6-month angiographic follow-up demonstrated ≥90% angiographic occlusion. 21/28 (75%) were completely occluded at follow-up.

Conclusions

The LVIS device facilitated the coil embolization of wide-necked intracranial aneurysms with high rates of technical success, an excellent safety profile, and very high rates of complete and near-complete occlusion at follow-up.

Trial registration number

NCT01541254.

Delayed migration of a pipeline embolization device

BACKGROUND

Giant and complex aneurysms are increasingly treated with the Pipeline Embolization Device (PED). However, clinical experience with the device remains preliminary.

OBJECTIVE

To report the first case of a delayed migration of an intracranial PED.

METHODS

A 61-year-old woman with a known large right cavernous internal carotid artery aneurysm had a 3-month history of increasing retro-orbital pain. She underwent uneventful treatment of her aneurysm with the PED.

RESULTS

Five months after the procedure, the patient's pain recurred. On the routine 6-month follow-up angiography, there was proximal PED migration, with the distal end of the device projecting directly into the aneurysm and creating a jet of contrast against the aneurysm sac. The migration distance was more than 1 cm, and there was significant foreshortening of the device. A second, overlapping PED was successfully deployed within the first PED to bridge the neck of the aneurysm and redirect the flow jet away from the aneurysm sac. Complete resolution of the patient's symptoms was noted 4 weeks later.

CONCLUSION

Delayed proximal migration may occur after placement of a PED. Accurate stent sizing and adequate apposition to the vessel wall may minimize the occurrence of this undesirable phenomenon. If there is any concern regarding the position of the PED, early imaging follow-up may be indicated.

Spontaneous delayed migration/shortening of the pipeline embolization device: report of 5 cases

Five patients were found to have spontaneous delayed migration/shortening of their Pipeline Embolization Devices on follow-up angiography. The device migrated proximally in 4 patients and distally in 1 patient. One patient had a subarachnoid hemorrhage and died as a result of migration of the Pipeline Embolization Device, and another patient presented with complete MCA occlusion and was left severely disabled. Mismatch in arterial diameter between inflow and outflow vessels was a constant finding. Migration of the Pipeline Embolization Device was managed conservatively, with additional placement of the device, or with parent vessel occlusion. Obtaining complete expansion of the embolization device by using a longer device, increasing vessel coverage, using adjunctive aneurysm coiling, and avoiding dragging and stretching of the device are important preventive measures. Neurointerventionalists should be aware of this potentially fatal complication and take all necessary preventive measures.

Incomplete stent apposition in Enterprise stent-mediated coiling of aneurysms: persistence over time and risk of delayed ischemic events

OBJECT

Incomplete stent apposition of the closed cell-design Enterprise stent following stent-mediated coil embolization of intracranial aneurysms has been associated with increased risk of periprocedural thromboembolic events. In this study, the authors seek to determine the natural history of incomplete stent apposition and evaluate the clinical implications of the phenomenon.

METHODS

Since January 2009, all patients receiving Enterprise stents in the treatment of intracranial aneurysms at the authors' institution have undergone serial 3-T MRI with incomplete stent apposition identified by the crescent sign on multiplanar reconstructions of MR angiograms. Magnetic resonance images and MR angiograms obtained at 3, 9, and 18 months after stent-assisted coil embolization were analyzed along with admission and follow-up clinical medical records. These records were evaluated for any radiographic and clinical, transient or permanent ischemic neurological events.

RESULTS

Fifty patients receiving Enterprise stents were eligible for inclusion and analysis in the study. Incomplete stent apposition was identified in postoperative imaging studies in 22 (44%) of 50 patients, with 19 (86%) of 22 crescent signs persisting and 3 (14%) of 22 crescent signs resolving on subsequent serial imaging. Delayed ischemic events occurred in 8 (16%) of 50 cases, and all cases involved patients with incomplete stent apposition. The events were transient ischemic attacks (TIAs) in 5 cases, asymptomatic radiographic strokes in 2 cases, and symptomatic strokes and TIAs in the final case. There were no delayed ischemic events in patients who did not have incomplete stent apposition. Only 1 of the delayed ischemic events (2%) was permanent and symptomatic. The postoperative presence of a crescent sign and persistence of the crescent sign were both significantly associated with delayed ischemic events (p < 0.001 and p = 0.002, respectively).

CONCLUSIONS

Incomplete stent apposition is a temporally persistent phenomenon, which resolves spontaneously in only a small minority of cases and appears to be a risk factor for delayed ischemic events. Although further follow-up is needed, these results suggest that longer duration of antiplatelet therapy and clinical follow-up may be warranted in cases of recognized incomplete stent apposition.

Treatment of a pediatric recurrent fusiform middle cerebral artery (MCA) aneurysm with a flow diverter

Pediatric patients with aneurysm often have different localizations and morphologies from adults and recurrences are not uncommon after successful clip reconstruction/obliteration. Treatment of a recurrent pediatric aneurysm after clip ligation is a technical challenge. We present the case of an adolescent with a middle cerebral artery (MCA) fusiform aneurysm which recurred following clip reconstruction and bypass. The aneurysm was successfully treated with endovascular flow diversion.