Microsurgical Treatment for Complex Basilar Artery Aneurysms with Long-Term Follow-Up in a Series of 35 Cases

Cerebral revascularization for complex vertebrobasilar artery dissecting aneurysms

Vertebrobasilar artery dissecting aneurysms (VBDAs) are the most surgically challenging type of aneurysm. Cerebral revascularization is the ultimate treatment for complex VBDAs. We retrospectively analysed the characteristics, surgical outcomes and follow-up data of 21 patients who underwent cerebral revascularization to treat complex VBDAs from 2015 to 2022. According to the location of the aneurysm and the anatomic relationship between the VBDA and the PICA, VBDA patients were classified into four groups: aneurysms located at the VA with PICA involvement (10 patients), aneurysms located at the VA without PICA involvement (1 patient), aneurysms located at the basilar apex segment (1 patient) and aneurysms located at the basilar trunk segment (9 patients). A surgical algorithm for complex VBDAs was determined primarily by the location of the aneurysm, the status of the aneurysm and the ability of retrograde blood flow to reach the proximal vertebrobasilar artery. Surgical modalities for patients with aneurysms in the VA with PICA involvement included low-flow (OA-PICA) bypasses with aneurysm trapping, aneurysm excision or reconstructive clip in 8 patients and STA-PCA bypass combined with PICA preservation and aneurysm trapping in 2 patients. In patients with aneurysms in the VA without PICA involvement, aneurysm excision was performed without cerebral bypass. In patients with aneurysms in the basilar apex segment, high-flow bypass (ECA-RA-P2) with aneurysm trapping was performed. In patients with aneurysms in the basilar trunk segment, surgical modalities included high-flow bypasses (ECA-RA-P2 and LVA-RA-P2) with aneurysm trapping or proximal occlusion in 6 patients, ECA-RA-P2 bypass with partial proximal occlusion in 1 patient, ECA-RA-P2 bypass alone in 1 patient, and STA-PCA bypass with R-VA narrowing in 1 patient. Of the 21 patients, 20 experienced clinical improvement or no change, and 17 of 21 patients achieved favourable functional outcomes (mRS ≤ 2). However, one patient died of infarction and respiratory failure postoperatively. Aneurysms were completely obliterated in 13 patients, shrank in 5 patients and stabilized in 2 patients. The median follow-up period was 32.5 months. During the follow-up period, all bypasses were patent, and further clinical improvement was observed in 11 patients. Cerebral revascularization appears to be safe and effective for the treatment of complex VBDAs, and cerebral revascularization could act as a complementary treatment strategy.

Efficacy and Safety of Extracranial-Intracranial Bypass Surgery for Posterior Circulation Aneurysms: A Systematic Review and Single-Arm Meta-Analysis

OBJECTIVE

Treating complex posterior circulation aneurysms poses challenges, and extracranial to intracranial (EC-IC) bypass techniques are potential therapeutic options. However, the safety and efficacy of this approach for posterior circulation aneurysms remain unclear. The study's objective was to assess the safety and efficacy of EC-IC bypass in these aneurysms.

METHODS

Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, we conducted a systematic review on EC-IC revascularization for posterior circulation aneurysms. Included studies had at least 4 patients and reported data on mortality, patency, complications, or clinical outcomes. Favorable clinical outcomes were defined as modified Rankin Scale below 3 or Glasgow Outcome Scale above 3, and complications were any issues related to the bypass procedure.

RESULTS

From 3036 articles reviewed, 22 studies involving 196 patients who underwent 210 EC-IC bypass procedures for posterior circulation aneurysms were selected. The median follow-up period of 14 studies was 31.66 months (6-61 months). Final follow-up indicated a high bypass patency rate of 96% [95% confidence interval [CI]: 91%-100%; I2 = 12%], with a mortality rate of 5% [95% CI: 1%-9%; I2 = 0%]. Additionally, 83% [95% CI: 70%-96%; I2 = 77%] of patients showed good outcomes at the last follow-up. Complications were observed in 40% [95% CI: 26%-55%; I2 = 80%]. Heterogeneity was associated with specific studies.

CONCLUSIONS

EC-IC bypass procedures are a viable treatment option for posterior circulation aneurysms, with high bypass patency rates and favorable clinical outcomes. However, complications, especially neurological deficits, exist. Open revascularization remains essential for neurovascular surgeons dealing with complex aneurysms.

Reconstructive Endovascular Treatment of Basilar Trunk and Vertebrobasilar Junction Aneurysms: A Review of 77 Consecutive Cases

Background

Basilar trunk and vertebrobasilar junction (BTVBJ) aneurysms have a poor prognosis and are challenging to treat.

Objective

This study aimed to evaluate the efficacy of reconstructive endovascular treatment for BTVBJ aneurysms and explore a treatment selection paradigm.

Methods

Clinical and angiographic data from 77 patients with 80 BTVBJ aneurysms who underwent endovascular treatment with flow diverters (FDs) or conventional stent-assisted coiling between January 2016 and December 2020 were retrospectively analyzed. Aneurysm characteristics and treatment outcomes were compared between treatment groups.

Results

Among the 77 study patients, 34 (44.2%) were treated with FDs and 43 (55.8%) with conventional stent-assisted coiling. Overall, 72.7% of patients achieved favorable clinical outcome at follow-up. The rate of procedure-related complications was 23.4%. The aneurysm occlusion rate at last follow-up did not differ between the FD and conventional stent groups (79.2% vs. 77.1%, p = 0.854). Although the occlusion rate immediately after the procedure was lower in the FD group (29.4%), incidence of progressive occlusion was significantly higher (62.5 vs. 5.7%; p < 0.001). The proportion of patients with large and giant aneurysms (≥10 mm) was significantly higher in the FD group (70.6 vs. 34.8%; p = 0.002). In patients with large or giant aneurysms, favorable clinical outcome at last follow-up was achieved in 75% of patients in the FD group but only 43.8% of patients in the conventional stent group (p = 0.046). Moreover, the complication rate was lower in the FD group, but the difference was not significant (20.8 vs. 37.5%; p = 0.247). The same analyses were performed for patients with small aneurysms (<10 mm) but no significant differences between the two groups were observed.

Conclusion

Endovascular treatment of small BTVBJ aneurysms using either FDs or conventional stents was feasible and effective. In patients with large or giant aneurysms, treatment using FDs achieved higher rates of occlusion and favorable clinical outcome at last follow-up than conventional stent-assisted coiling.

Endovascular Therapy for Basilar Arterial Trunk Aneurysms

Background: Although aneurysms rarely occur in the basilar artery (BA) trunk, the majority of those that do are dissection aneurysms. Currently, the mainstream therapy for BA trunk aneurysms is endovascular therapy (EVT), which mainly includes single coiling or conventional low-metal-coverage stent-assisted EVT, but the efficacy remains to be evaluated. Methods: A retrospective study was performed for the patients who were admitted to our institution for BA trunk aneurysms and underwent EVT. A total of 28 patients were collected in this study. Results: The patients were aged 23-71 years (53.7 ± 11.5 years on average); nine were female (32.1%, 9/28), and 19 were male (67.9%, 19/28). The patients were given single coiling or conventional low-metal-coverage stent-assisted EVT. Among the 28 patients, 10 (35.7%, 10/28) developed complications, 90% (9/10) of which were ischemic and 10% (1/10) were hemorrhagic. Among the 28 patients, 5 (17.9%, 5/28) died. The surviving 23 patients (82.1%, 23/28) recovered well. Conclusions: This study found that for BA trunk aneurysms, single coiling or conventional low-metal-coverage stent-assisted EVT still had some risks. The risks are mainly from brainstem ischemia. Therefore, the perforators of the BA trunk must be carefully evaluated and prevented from receiving damage from the EVT procedure. This study also shows that 82.1% of patients recovered well. Therefore, EVT can result in an acceptable prognosis.

An endovascular assisted, nonocclusive cerebral bypass: a technical feasibility study in a rabbit model

OBJECTIVE

Temporary parent vessel occlusion performed to establish a high-flow interpositional bypass carries the risk of infarcts. The authors investigated the feasibility of a novel technique to establish a high-flow bypass without temporary parent vessel occlusion in order to lower the risk of ischemic complications.

METHODS

In 10 New Zealand white rabbits, a carotid artery side-to-end anastomosis was performed under parent artery patency with a novel endovascular balloon device. Intraoperative angiography, postoperative neurological assessments, and postoperative MRI/MRA were performed to evaluate the feasibility and safety of the novel technique.

RESULTS

A patent anastomosis was established in 10 of 10 animals; 3 procedure-related complications occurred. No postoperative focal neurological deficits were observed. The MRI/MRA findings include no infarcts and bypass patency in 50% of the animals.

CONCLUSIONS

The authors demonstrated the feasibility of an endovascular assisted, nonocclusive high-flow bypass. Future refinement of the device and technique in an animal model is necessary to lower the complication rate and increase patency rates.

Postoperative Antiplatelet Therapy in the Treatment of Complex Basilar Apex Aneurysms Implementing Hunterian Ligation and Extracranial-to-Intracranial Bypass: Review of the Literature with an Illustrative Case Report

Large broad-based basilar artery (BA) apex aneurysms involving multiple arterial origins are complex lesions commonly not amenable to direct clipping or endovascular management. BA proximal (Hunterian) occlusion with extracranial-to-intracranial bypass is a supported strategy if 1 or both posterior communicating arteries are small. Hunterian ligation risks sudden aneurysm thrombosis and thromboembolism in the perforator-rich BA apex. There currently exist no guidelines for antiplatelet and anticoagulant therapy after Hunterian ligation for complex BA apex aneurysm treatment. We present a literature review and an illustrative case of an 18-year-old man who presented with progressive headaches and was found to have a large unruptured BA apex aneurysm involving the origins of the bilateral superior cerebellar and posterior cerebral arteries. Given the small posterior communicating arteries and complexity of the aneurysm, proximal BA occlusion with unilateral superficial temporal artery-to-superior cerebellar artery bypass was recommended. Despite antiplatelet treatment with acetylsalicylic acid before and after operation, the patient experienced acute ischemia of the brainstem and cerebellum and an embolic left temporal lobe infarct. The patient received dual antiplatelet therapy starting on postoperative day 6, after which he experienced no new infarcts and made a significant neurologic recovery. The current evidence suggests that proximal BA occlusion in complex BA apex aneurysm cases is thrombogenic and can be especially dangerous if thrombosis occurs suddenly in aneurysms without pre-existing intraluminal thrombus. Dual antiplatelet therapy during the first postoperative week presents a possible strategy for reducing the risk of ischemia due to sudden aneurysm thrombosis.