Application of the Neuroform Atlas Stent in Intracranial Aneurysms: Current Status

Initial Experience with a New Self-Expanding Open-Cell Stent System with Antithrombotic Hydrophilic Polymer Coating (pEGASUS Stent) in the Treatment of Wide-Necked Intracranial Aneurysms

PURPOSE

We report our initial experience with endovascular embolization of intracranial aneurysms using this new self-expanding open-cell stent system (pEGASUS stent system) with the antithrombogenic hydrophilic polymer coating.

MATERIALS AND METHODS

We retrospectively reviewed all patients treated with stent-assisted coiling or the Woven EndoBridge device using the pEGASUS stent system between September 2022 and June 2023. Demographic, clinical, and angiographic data were analyzed as well as short-term follow-up, including procedural complication rates and aneurysmal occlusion rates using the Raymond-Roy occlusion classification (RROC).

RESULTS

Twelve patients with 12 wide-necked intracranial aneurysms were treated with the pEGASUS stent system, including 2 acutely ruptured aneurysms embolized in an emergency setting. The treated aneurysms were located at the anterior communicating artery (25.0%), the basilar artery (50.0%), the middle cerebral artery (16.7%), and the internal carotid artery (8.3%). All stents were deployed successfully. Immediate complete aneurysmal occlusion (RROC class I) was achieved in 83.3% (10/12) and near-complete occlusion (RROC II) in 16.7% (2/12). No periprocedural complications occurred in patients treated in the elective setting. A single case of intraoperative in-stent thrombus formation occurred during the treatment of an acutely ruptured basilar aneurysm and was resolved with intravenous Tirofiban. No other periprocedural complications occurred. Eleven out of 12 patients were available for follow up (mean 7.4 months). Complete aneurysmal occlusion without in-stent stenosis (ISS) was seen in 10 patients (90.9%). One patient (9.1%) showed aneurysmal reperfusion (RROC IIIb) with asymptomatic moderate ISS.

CONCLUSION

Our initial results demonstrate that the pEGASUS stent system appears to be a safe and effective device for stent assisted embolization of wide-necked intracranial aneurysms. More data is necessary to evaluate long-term follow-up.

Evaluating Changes in Pulsatile Flow With Endovascular Stents in an In Vitro Blood Vessel Model: Potential Implications for the Future Management of Neurovascular Compression Syndromes

BACKGROUND

Neurovascular compression syndromes (NVCS), encompassing conditions such as trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia, significantly impair patient quality of life through abnormal vascular compression and micro-pulsation of vasculature on cranial nerves at the Obersteiner-Redlich zone. The modulation of pulsatile flow dynamics via endovascular stents presents a novel research frontier for alleviating these syndromes.

AIM

The primary aim of this investigation was to delineate the impact of various endovascular stents on pulsatile flow within an in vitro model of a blood vessel, thereby elucidating their potential applicability in the therapeutic management of NVCS.

MATERIALS AND METHODS

A simple in vitro analog of a posterior circulation artery was developed, employing an intravenous pump to replicate cardiac-induced blood flow. Within this model, alterations in pulsatile flow were quantitatively assessed following the introduction of three categorically distinct endovascular stents, varying in size. This assessment was facilitated through the employment of both micro-Doppler and Doppler ultrasound methodologies.

RESULTS

The Pipeline 5x35 mm stent (Medtronic, Minneapolis, MN) demonstrated the most significant reductions in peak systolic velocity (Vmax) and pulsatility index (PI), PI especially over the stent, suggesting its potential for drastically altering blood flow dynamics. Similarly, Neuroform Atlas 4.5x30 mm and Neuroform Atlas 4x24 mm stents (Stryker, Kalamazoo, MI) also showed notable decreases in hemodynamic parameters, albeit to different extents. Statistical analysis confirmed that these changes were significantly different from the control (P < 0.0001 for PI and Vmax; P < 0.05 for inter-stent comparisons), except for proximal PI means, which did not significantly differ from the control (P = 0.2777).

CONCLUSION

These findings affirm the potential of endovascular stents to substantially modulate arterial pulsatility. The observed decrease in pulsatile flow resultant from endovascular stent application has the potential to attenuate ectopic nerve excitation, a hallmark of NVCS. Consequently, this research highlights the prospective utility of endovascular stents in developing minimally invasive therapeutic approaches for NVCS.

Endovascular treatment of intracranial internal carotid artery bifurcation region aneurysms

Intracranial internal carotid artery (ICA) bifurcation region aneurysms are uncommon. When treatment is necessary for ICA, endovascular treatment (EVT) can be a useful option. Due to the complexity of these aneurysms and the variability of EVT techniques, EVT for ICA bifurcation aneurysms is challenging. Currently, it is necessary to perform a review to explore this issue further. In this review, the following issues were discussed: the anatomy of the ICA bifurcation region; the classification, natural history and EVT status of ICA bifurcation region aneurysms; the technique used for identifying ICA bifurcation region aneurysms; and the prognosis and complications of EVT for ICA bifurcation region aneurysms. According to the review and our experience, traditional coiling is currently the preferred therapy for ICA bifurcation region aneurysms. In addition, in select cases, new devices, such as flow diverters and Woven EndoBridge devices, can also be used to treat ICA bifurcation region aneurysms. Generally, EVT is an alternative treatment option for ICA bifurcation region aneurysms.

Silent Embolic Infarction after Neuroform Atlas Stent-Assisted Coiling of Unruptured Intracranial Aneurysms

OBJECTIVE

There is still controversy regarding whether neck remodeling stent affects the occurrence of silent embolic infarction (SEI) after aneurysm coiling. Thus, the aim of the present study is to investigate the incidence of SEI after stent-assisted coiling (SAC) using Neuroform Atlas Stent (NAS) and possible risk factors. This study also includes a comparison with simple coiling group during the same period to estimate the impact of NAS on the occurrence of SEI.

METHODS

This study included a total of 96 unruptured intracranial aneurysms in 96 patients treated with SAC using NAS. Correlations of demographic data, aneurysm characteristics, and angiographic parameters with properties of SEI were analyzed. The incidence and characteristics of SEI were investigated in 28 patients who underwent simple coiling during the same period, and the results were compared with the SAC group.

RESULTS

In the diffusion-weighted imaging obtained on the 1st day after SAC, a total of 106 SEI lesions were observed in 48 (50%) of 96 patients. Of these 48 patients, 38 (79.2%) had 1-3 lesions. Of 106 lesions, 74 (69.8%) had a diameter less than 3 mm. SEI occurred more frequently in older patients (≥60 years, p=0.013). The volume of SEI was found to be significantly increased in older age (≥60 years, p=0.032), hypertension (p=0.036), and aneurysm size ≥5 mm (p=0.047). The incidence and mean volume of SEI in the SAC group (n=96) were similar to those of the simple coiling group (n=28) during the same period.

CONCLUSION

SEIs are common after NAS-assisted coiling. Their incidence in SAC was comparable to that in simple coiling. They occurred more frequently at an older age. Therefore, the use of NAS in the treatment of unruptured intracranial aneurysm does not seem to be associated with an increased risk of thromboembolic events if antiplatelet premedication has been performed well.

A comparison of Atlas and Leo Baby stents-assisted coiling of intracranial aneurysms with small parent vessels

Some studies have reported the efficacy and safety of the Atlas stent and the Leo Baby stent-assisted coiling (SAC) of intracranial aneurysms arising from small cerebral vessels. The authors aimed to compare the clinical performance of the Atlas and the Leo Baby stents in small parent arteries.

METHODS AND MATERIALS

Between January 2019 and November 2022, 56 patients at our centre were treated using either Atlas or Leo Baby SAC of intracranial aneurysms arising from small parent vessels (<2 mm). The clinical and angiographic imaging data of the two cohorts were retrospectively collected and comparatively analyzed.

RESULTS

A total of 56 patients were included in this study. Thirty-two patients were treated with the Atlas SAC, and 24 patients were treated with the Leo Baby SAC. The mean age of the Atlas stent cohort was older, and the mean aneurysm size was smaller than the Leo Baby stent. The immediate complete occlusion rate was 68.6% in the Atlas stent cohort and 62.5% in the Leo Baby stent cohort. The mean angiographic follow-up time for Atlas stent cohort was 8.9±2.5 months, and the final aneurysm complete occlusion rate was 81.0%. The mean follow-up time for Leo Baby stent cohort was 18.9±6.0 months, and the final aneurysm complete occlusion rate was 83.3%.

CONCLUSIONS

At the final follow-up, the Atlas or the Leo baby stent SAC of intracranial aneurysms with small parent vessels resulted in favourable angiographic results and clinical outcomes, with a low rate of associated complications.

Additional rescue stenting with Neuroform Atlas stents during stent-assisted coiling of saccular aneurysms

OBJECTIVE

Overlapping stenting is sometimes attempted during endovascular treatment of cerebral aneurysm as a rescue for coil herniation, stent mal-positioning, or in-stent thrombosis. We retrospectively evaluated the efficacy and safety of additional rescue stenting (ARS) in telescoping fashion with Neuroform Atlas stent (NAS) during stent-assisted coiling of saccular aneurysms.

METHODS

We collected clinical and radiological data of patients with saccular aneurysms treated with ARS using NASs between March 2018 and December 2021. Y or X-stent-assisted coiling technique was excluded.

RESULTS

Eighteen unruptured and 5 ruptured aneurysms in 23 patients were treated with ARS using NASs. Sizes of aneurysms ranged from 2.0 mm to 10.0 mm (mean: 5.0 mm). Immediate angiographic results were complete occlusion in 11 aneurysms, residual neck in 4 aneurysms, and residual sac in 8 aneurysms. Peri-operative morbidity was 4.3 %. Nineteen of 23 patients underwent follow-up conventional angiography (mean, 9.9 months). Results showed progressive occlusion in 10 (52.6 %) cases and asymptomatic in-stent stenosis in 3 (15.8 %) cases. At the end of the observation period (mean, 17.4 months), all 18 patients without subarachnoid hemorrhage had excellent clinical outcomes (mRS of 0), except one (mRS of 1). Of five patients with subarachnoid hemorrhage, four had a favorable outcome (mRS of 0-1), while the other one was dependent (mRS of 4).

CONCLUSION

In this report on 23 patients, ARS with NASs for treating saccular aneurysms showed good technical safety with favorable clinical and angiographic outcomes. However, delayed in-stent stenosis was not uncommon. Thus, regular imaging follow-up is required.

Stenting-assisted embolization of a saccular aneurysm of the azygos anterior cerebral artery associated with fenestration at its beginning

Aneurysms of the azygos anterior cerebral artery (AACA) associated with fenestration are exceptional. We reported such a case. A 61-year-old woman presented with subarachnoid hemorrhage. Computed tomography angiography and digital subtraction angiography showed an aneurysm at the distal end of the AACA with a fenestration at its beginning. Stenting-assisted coiling of the aneurysm was performed. The postoperative recovery was uneventful. Follow-up DSA showed complete coiling of the aneurysm. By this case report and review of the literature, we found that the coexistence of the aneurysm and fenestration on the AACA was exceptional. Endovascular treatment of saccular AACA aneurysms is an appealing option.

Endovascular treatment of a supraclinoid internal carotid artery fenestration aneurysm: A case report and literature review

Supraclinoid internal carotid artery (ICA) fenestration aneurysm is rare. Except for open surgery, endovascular treatment (EVT) is considered an alternative for such an aneurysm. However, experience with this procedure is lacking. Therefore, we reported such a case. A 61-year-old woman suffered subarachnoid hemorrhage. Digital subtracted angiography (DSA) showed bilateral middle cerebral artery (MCA) aneurysms and a saccular aneurysm associated with fenestration of the supraclinoid ICA. Two MCA aneurysms were treated with single coiling, and the supraclinoid ICA fenestration aneurysm was coiled under stent assistance. The postoperative recovery was uneventful. At this time, a literature review was performed on the role of EVT in supraclinoid ICA fenestration aneurysms. A total of 13 supraclinoid ICA fenestration aneurysms treated by EVT in 11 cases, including our case, were obtained. After EVT, good outcomes were obtained in all cases. To our knowledge, this is the first study to review the role of EVT for supraclinoid ICA fenestration aneurysms. Our case report and literature review indicated that EVT for such aneurysms may be feasible and act as a therapeutic alternative.

Endovascular treatment of aneurysms of the paraophthalmic segment of the internal carotid artery: Current status

The paraophthalmic segment of the internal carotid artery (ICA) originates from the distal border of the cavernous ICA and terminates at the posterior communicating artery. Aneurysms arising from the paraophthalmic segment represent ~5–10% of intradural aneurysms. Due to the advent of endovascular treatment (EVT) techniques, specifically flow-diverting stents (FDSs), EVT has become a good option for these aneurysms. A literature review on EVT for paraophthalmic segment aneurysms is necessary. In this review, we discuss the anatomy of the paraophthalmic segment, classification of the paraophthalmic segment aneurysms, EVT principle and techniques, and prognosis and complications. EVT techniques for paraophthalmic segment aneurysms include coil embolization, FDSs, covered stents, and Woven EndoBridge devices. Currently, coiling embolization remains the best choice for ruptured paraophthalmic segment aneurysms, especially to avoid long-term antiplatelet therapy for young patients. Due to the excessive use of antiplatelet therapy, unruptured paraophthalmic segment aneurysms that are easy to coil should not be treated with FDS. FDS is appropriate for uncoilable or failed aneurysms. Other devices cannot act as the primary choice but can be useful auxiliary tools. Both coiling embolization and FDS deployment can result in a good prognosis for paraophthalmic segment aneurysms. The overall complication rate is low. Therefore, EVT offers promising treatments for paraophthalmic segment aneurysms. In addition, surgical clipping continues to be a good choice for paraophthalmic segment aneurysms in the endovascular era.

CTA Study of Ruptured Aneurysms of the Posterior Communicating Artery

Background. Only a few reported studies have used computed tomography angiography (CTA) to image ruptured aneurysms at the junction of the internal carotid artery (ICA) and posterior communicating artery (PcomA) in the context of the adjacent arteries. Therefore, we performed such a study using a GE Workstation. Methods. The parameters of each aneurysm and its adjacent arteries were measured. Then, statistical assessments were performed to compare the parameters of the aneurysm side and the lesion-free (control) side. Results. Sixty-three patients were included in this study. The average age was $62.1\pm 11.0$ years, and the ratio of males to females was 0.8 : 1. The measurement results showed that the mean aneurysmal height was $5.2\pm 2.3$  mm, the mean width was $4.7\pm 2.2$ mm, and the mean neck width was $4.5\pm 1.9$ mm. On the aneurysm side, the intradural ICA diameter was $4.34\pm 0.90$  mm, and the diameter of the ICA at its termination was $3.55\pm 0.72$ mm. A fetal-type PcomA was found in 52.4% of aneurysms. The other measured parameters were also provided. Statistical results showed that the height of the aneurysm was larger than the width ( $P<0.05$ ). The intradural ICA diameter, the ICA diameter at termination, the intradural ICA length, and the angle between the ICA and PcomA were larger in the aneurysm group than in the control group ( $P<0.05$ ). Conclusions. This CTA study showed that the ruptured PcomA aneurysm was often wide-necked, nonspherical, and approximately 5 mm in size. In the presence of a ruptured PcomA aneurysm, the affected intradural ICA became thicker and longer than the contralateral control ICA, and the aneurysm significantly reduced the angle between the ICA and the PcomA.