Revascularization of the posterior circulation

C2-P2 Bypass: Technical Assessment of Petrous Carotid Artery to Posterior Cerebral Artery Interpositional Bypass Through the Combined Transcochlear-Subtemporal Approach as a Part of Microsurgical Treatment for Dolichoectatic Vertebrobasilar Artery Aneurysms

BACKGROUND AND OBJECTIVES

Managing dolichoectatic vertebrobasilar artery aneurysms requires a multifaceted approach. Revascularization of the posterior circulation with a high-flow bypass is part of the flow reversal paradigm. Performing a robust high-flow bypass and addressing the aneurysm through the same approach smooths the operative intervention. This study assessed the anatomic feasibility of accessing the basilar trunk and aneurysm simultaneously to revascularize the posterior circulation using a petrous internal carotid artery (pICA)-posterior cerebral artery (PCA) interpositional bypass through a complete petrosectomy.

METHODS

Six embalmed cadaveric heads (12 sides) underwent a combined extended transcochlear-subtemporal approach to expose the pICA and P2 PCA. A pICA (side-to-end) graft (end-to-side) PCA bypass was attempted. The lengths of the vessels relevant to the bypass and the graft length were measured.

RESULTS

The bypass was successfully completed in all specimens. The mean exposed lengths of the pICA and PCA were 21.3 and 20.0 mm, respectively. The mean length of the perforator-free zone on PCA was 11.2 mm. The mean length of the interposition graft was 36.6 mm.

CONCLUSION

The transcochlear approach can be used to expose the pICA as a donor for a high-flow bypass to the PCA as part of the treatment paradigm for dolichoectatic vertebrobasilar artery aneurysms. Careful patient selection and extensive knowledge of skull base anatomy are mandatory for this strategy.

When microsurgery becomes the only lifesaving resource: An institutional experience treating patients from low-income backgrounds affected by posterior circulation brain aneurysms

BACKGROUND AND OBJECTIVE

Aneurysms of the posterior cerebral circulation constitute a burdensome condition with high mortality and morbidity. In the modern era, there has been a trend toward favoring an endovascular approach over microsurgery for aneurysm cases. Nevertheless, this transition has yet to be mirrored in low-to-middle-income countries where endovascular therapy may not be widely available. Herein, we aim to illustrate our experience treating these challenging conditions in patients from low-income backgrounds and discuss the relevance of the clinical setting in the treatment decision.

METHODS

The authors conducted a retrospective review of the health records of patients who received microsurgical treatment for aneurysms in the posterior circulation, including the basilar artery (BA), posterior cerebral artery (PCA), and posterior inferior cerebellar artery (PICA) in an institution providing treatment to people of low-income backgrounds. Epidemiological data, microsurgical technique, and neurological function were retrieved and analyzed.

RESULTS

Surgical clipping was employed for 12 patients (75% female) harboring 15 aneurysms (87% in the posterior circulation and 62% ruptured at presentation). Aneurysms were predominately located in the BA (69%), followed by the PCA (15%) and PICA (15%). Among neurological complications, 25% of patients developed oculomotor nerve palsy. The mortality rate was 17% owing to complications such as cerebral vasospasm, infarction, and severe intracranial hypertension. At the 6-month follow-up, 90% of patients had a good clinical outcome (modified Rankin scale scores of 0-2).

CONCLUSION

The present case series illustrates the manifest role of microsurgical techniques for posterior circulation aneurysms, particularly in a scenario where endovascular techniques are not easily accessible. Importantly, this clinical setting pressure could exhort trainees to strive for microsurgical mastery and gain a competitive advantage.

Moyamoya Disease in a Patient With Sickle Cell Disease: A Case Report and Review of the Literature

Moyamoya disease (MMD) is a relatively rare, progressively worsening steno-occlusive condition primarily characterized by a progressive narrowing of the intracranial arteries, causing hypoperfusion and consequent cerebral ischemia and infarction. This case report discusses the rare presentation of a patient who was known to have sickle cell disease and MMD. Various investigations have revealed a typical presentation of such a disease through radiological findings. Our report highlights this rare disease and its possible association with other comorbidities, as well as the medical treatment options that patients may undergo with the option of surgical treatment.

Posterior cerebral territory ischemia in pediatric moyamoya: Surgical techniques and long-term clinical and radiographic outcomes

PURPOSE

To describe a surgical technique for posterior cerebral revascularization in pediatric patients with moyamoya arteriopathy. Here, we describe the clinical characteristics, surgical indications, operative techniques, and clinical and radiographic outcomes in a series of pediatric patients with moyamoya disease affecting the posterior cerebral artery (PCA) territory.

METHODS

A retrospective single-center series of all pediatric patients with moyamoya disease who presented to our institute between July 2009 through August 2019 were reviewed. The clinical characteristics, surgical indications, operative techniques, and long-term clinical and radiographic outcomes of pediatric moyamoya patients with PCA territory ischemia were collected and analyzed.

RESULTS

A total of 10 PCA revascularization procedures were performed in 9 patients, 5 female, ages 1 to 11.1 years (average 5.2 years). Complications included 1 stroke, with no infections, hemorrhages, seizures, or deaths. One patient had less than 1 year of radiographic and clinical follow-up. In 8 of 9 patients with at least 1 year of radiographic follow-up, there was engraftment of surgical vessels present in all cases. No new strokes were identified on long-term follow-up despite the radiographic progression of the disease. In the 8 cases available for analysis, the average follow-up was 50.8 months with a range of 12 to 117 months.

CONCLUSIONS

PCA territory ischemia in patients with progressive moyamoya disease can be surgically treated with indirect revascularization. Here, we describe our experience with PCA revascularization procedures for moyamoya disease, including pial pericranial dural (PiPeD) revascularization and pial synangiosis utilizing the occipital artery. These surgical options may be useful for decreasing the risk of stroke in pediatric moyamoya patients with severe posterior circulation disease.

External carotid artery-radial artery graft-posterior cerebral artery bypass for complex vertebrobasilar aneurysms: efficacy and analysis of outcome in a single center

The purpose of this research was to demonstrate the effectiveness and clinical outcome of an external carotid artery-radial artery graft-posterior cerebral artery (ECA-RAG-PCA) bypass in the treatment of complex vertebrobasilar artery aneurysms (VBANs) in a single-center retrospective study. An ECA-RAG-PCA bypass may be a last and very important option in the treatment of complex VBANs when conventional surgical clipping or endovascular interventions fail to achieve the desired outcome. This study retrospectively analyzed the clinical presentation, case characteristics, aneurysm location, size and morphology, choice of surgical strategy, complications, clinical follow-up, and prognosis of the patients enrolled. The data involved were analyzed by the appropriate statistical methods. A total of 24 patients with complex VBANs who met the criteria were included in this study. Eighteen (75.0%) were male and the mean age was 54.1 ± 8.83 years. The aneurysms were located in the vertebral artery, the basilar artery, and in the vertebrobasilar artery with simultaneous involvement. All patients underwent ECA-RAG-PCA bypass surgery via an extended middle cranial fossa approach, with 8 (33.3%) undergoing ECA-RAG-PCA bypass only, 3 (12.5%) undergoing ECA-RAG-PCA bypass combined with aneurysm partial trapping, and 12 (50.0%) undergoing ECA-RAG-PCA bypass combined with proximal occlusion of the parent artery. The average clinical follow-up was 22.0 ± 13.35 months. The patency rate of the high-flow bypass was 100%. At the final follow-up, 15 (62.5%) patients had complete occlusion of the aneurysm, 7 (29.2%) patients had subtotal occlusion of the aneurysm, and 2 (8.3%) patients had stable aneurysms. The rate of complete and subtotal occlusion of the aneurysm at the final follow-up was 91.7%. The clinical prognosis was good in 21 (87.5%) patients and no procedure-related deaths occurred. Analysis of the good and poor prognosis groups revealed a statistically significant difference in aneurysm size (P = 0.034, t-test). Combining the results of this study and the clinical experience of our center, we propose a surgical algorithm and strategy for the treatment of complex VBANs.The technical approach of ECA-RAG-PCA bypass for complex VBANs remains important, even in an era of rapid advances in endovascular intervention. When conventional surgical clipping or endovascular intervention has failed, an ECA-RAG-PCA bypass plays a role that cannot be abandoned and is a very important treatment option of last resort.

Vertebral Artery Interventions: A Comprehensive Updated Review

Patients with posterior circulation ischemia due to vertebral artery stenosis account for 20 to 25% of ischemic strokes and have an increased risk of recurrent stroke. In patients treated with medical therapy alone, the risk of recurrence is particularly increased in the first few weeks after symptoms occur, with an annual stroke rate of 10 to 15%. Additionally, obstructive disease of the vertebrobasilar system carries a worse prognosis, with a 30% mortality at 2-years if managed medically without additional surgical or endovascular intervention. Percutaneous transluminal angioplasty and stenting of symptomatic vertebral artery stenosis are promising options widely used in clinical practice with good technical results; however, the improved clinical outcome has been examined in various clinical trials without a sufficient sample size to conclusively determine whether stenting is better than medical therapy. Surgical revascularization is an alternative approach for the treatment of symptomatic vertebral artery stenosis that carries a 10-20% mortality rate. Despite the advances in medical therapy and endovascular and surgical options, symptomatic vertebral artery stenosis continues to impose a high risk of stroke recurrence with associated high morbidity and mortality. This review aims to provide a focused update on the percutaneous treatment of vertebral artery stenosis, its appropriate diagnostic approach, and advances in medical therapies.

Revascularization of the Posterior Inferior Cerebellar Artery Using the Occipital Artery: A Cadaveric Study Comparing the p3 and p1 Recipient Sites

BACKGROUND

Revascularization of the posterior inferior cerebellar artery (PICA) is typically performed with the occipital artery (OA) as an extracranial donor. The p3 segment is the most accessible recipient site for OA-PICA bypass at its caudal loop inferior to the cerebellar tonsil, but this site may be absent or hidden due to a high-riding location.

OBJECTIVE

To test our hypothesis that freeing p1 PICA from its origin, transposing the recipient into a shallower position, and performing OA-p1 PICA bypass with an end-to-end anastomosis would facilitate this bypass.

METHODS

The OA was harvested, and a far lateral craniotomy was performed in 16 cadaveric specimens. PICA caliber and number of perforators were measured at p1 and p3 segments. OA-p3 PICA end-to-side and OA-p1 PICA end-to-end bypasses were compared.

RESULTS

OA-p1 PICA bypass with end-to-end anastomosis was performed in 16 specimens; whereas, OA-p3 PICA bypass with end-to-side anastomosis was performed in 11. Mean distance from OA at the occipital groove to the anastomosis site was shorter for p1 than p3 segments (30.2 vs 48.5 mm; P < .001). Median number of perforators on p1 was 1, and on p3, it was 4 (P < .001).

CONCLUSION

Although most OA-PICA bypasses can be performed using the p3 segment as the recipient site for an end-to-side anastomosis, a more feasible alternative to conventional OA-p3 PICA bypass in cases of high-riding caudal loops or aberrant anatomy is to free the p1 PICA, transpose it away from the lower cranial nerves, and perform an end-to-end OA-p1 PICA bypass instead.

Occipital artery to p3 segment of posterior inferior cerebellar artery bypass in treating a complex fusiform aneurysm

We provide a case report of a 58-year-old man who presented with a ruptured fusiform dissecting aneurysm located at the junction of the vertebral artery and posterior inferior cerebellar artery (PICA). Due to the lesion's complexity, a two-step approach was planned for revascularisation of PICA using the occipital artery (OA) prior to coiling embolisation. An end-to-side OA-PICA bypass was performed with implantation at the caudal loop of the p3 PICA segment. Fifteen days after the procedure, the aneurysm underwent stent-assisted coiling for successful obliteration of the aneurysm. The patient tolerated this procedure well and now at 1.5 years of follow-up remains free from any neurological deficits (modified Rankin Score 0). This case report illustrates one of the unique scenarios where both the vascular territory involved and morphological features of the aneurysm prohibited the use of more conventional means, necessitating the use of an arterial bypass graft for successful treatment of this lesion. As open vascular surgery is becoming less common in the age of endovascular coiling, our article uniquely reports on the combined use of both endovascular and microsurgical techniques to treat a complex aneurysm of the posterior circulation.

Current Open Surgical Indications for Revascularization in Cerebral Ischemia

Cerebral revascularization was pioneered half a century ago. Gradual improvements in microsurgical instrumentation and training in microsurgical techniques have allowed significant changes that improved outcomes in neurosurgery, extrapolating this knowledge to other neurosurgical diseases (brain tumor, aneurysms, and skull base tumor surgery). But the popularity of cerebral bypass procedures was followed by their decline, given the lack of clear benefit of bypass surgery in chronic cerebrovascular ischemia after the EC-IC bypass studies. Over the last couple of decades, the formidable advance of neuro-endovascular techniques for revascularization has lessened the need for application of open cerebral revascularization procedures, either for flow augmentation or flow replacement. However, there is still a select group of patients with chronic cerebral ischemia, for whom open cerebral revascularization with flow augmentation is the only treatment option available, and this will be the objective of our current review.

Extracranial-to-Intracranial Bypass for Refractory Vertebrobasilar Insufficiency

BACKGROUND

Vertebrobasilar insufficiency (VBI) is associated with high rates of morbidity and mortality, especially after failure of first-line medical and/or endovascular therapies. Although the optimal therapeutic strategy for refractory VBI remains unclear, surgical bypass represents a potentially life-saving treatment in this patient subset.

METHODS

A multi-institution retrospective database review was performed to identify patients with symptomatic refractory VBI over a 4-year period (July 2014 to July 2018). Surgical treatments, as well as clinical and neurologic outcomes were recorded.

RESULTS

Five patients were identified with refractory VBI (average age 55 ± 11.0 years). All 5 patients had clinically significant posterior circulation strokes on presentation. Three patients underwent superficial temporal artery-to-superior cerebellar artery bypass based on significant acute perfusion mismatches or progressive strokes despite maximal medical therapy; 1 surgical patient (33%) experienced punctate perioperative strokes and there were no significant bypass related complications. Functional outcomes in the 3 surgical patients were correlated with preoperative stroke burden. The remaining 2 patients experienced rapid neurologic declines after presentation that precluded bypass, and died shortly thereafter.

CONCLUSIONS

Refractory VBI has high morbidity, with cerebral bypass representing a safe and potentially efficacious treatment for selected patients. Long-term post-bypass outcomes are dependent on the level of irreversible preoperative neurologic injuries.

Minimum Transpetrosal Retrolabyrinthine Approach for Revascularization of Posterior Cerebral Artery: Operative Nuance

BACKGROUND

Revascularization of the posterior cerebral artery (PCA) can be essential for treating complex cerebral aneurysms in the posterior circulation, and it is considered technically challenging. To help decrease the difficulty of this technique, we developed the minimum transpetrosal approach (MTPA).

OBJECTIVE

The technical nuances of the MTPA were innovated by cadaver head dissections and an actual clinical case.

METHODS

Four sides of the formalin-fixed cadaver heads were used to investigate if the posterior cerebral artery could be exposed with this minimum retraction of the temporal lobe in the subtemporal approach and the MTPA. By using the MTPA, 1 patient harboring a ruptured PCA aneurysm underwent superficial temporal artery-PCA anastomosis followed by isolation of the aneurysm.

RESULTS

In the cadaver head dissections, we noticed that the PCAs were difficult to expose with gentle retraction of the temporal lobe in the subtemporal approach. By performing an additional retrolabyrinthine mastoidectomy, performed as the MTPA, all 4 PCAs were easily exposed in the 4 wide surgical fields. The maximum widths of the surgical fields above and below the PCA could be successfully measured in 2 cases, which were 13.3 mm and 11.2 mm, respectively (mean, 12.3 mm). Additionally, in the actual live surgery using MTPA, the PCAs were relative easy to expose with a surgical field wide enough to perform PCA bypass, which was performed without complication.

CONCLUSION

The MTPA may be the most favorable approach for PCA bypass that can be performed easily with minimal temporal lobe retraction.

Superficial temporal artery to proximal posterior cerebral artery bypass through the anterior temporal approach

Background:

The superficial temporal artery (STA) to proximal posterior cerebral artery (PCA) (P2 segment) bypass is one of the most difficult procedures to perform because the proximal PCA is located deep and high within the ambient cistern. STA to proximal PCA bypass is usually performed through a subtemporal approach or posterior transpetrosal approach, and rarely through a transsylvian approach. The aim of this study was to describe the operative technique of STA to proximal PCA bypass through a modified transsylvian approach (anterior temporal approach).

Methods:

STA to proximal PCA bypass was performed through an anterior temporal approach in three patients with intracranial aneurysm. We describe the details of the surgical technique.

Results:

The STA was successfully anastomosed to the proximal PCA in all cases. One patient suffered hemiparesis and aphasia due to infarction in the anterior thalamoperforating artery territory.

Conclusions:

STA to proximal PCA bypass can be performed through an anterior temporal approach in selected patients. We recommend that every precaution, including complete hemostasis, placement of cellulose sponges beneath the recipient artery to elevate the site of the anastomosis, and placement of a continuous drainage tube at the bottom of the operative field to avoid blood contamination during the anastomosis, should be taken to shorten the temporary occlusion time.

Aneurysms of the P2P Segment of Posterior Cerebral Artery: Case Report and Surgical Steps

The posterior cerebral artery (PCA) is divided into 4 segments: precommunicating segment (P1), postcommunicating segment (P2), quadrigeminal segment (P3), and calcarine segment (P4). Small aneurysms are more prevalent than large aneurysms in patients with ruptured aneurysms. P2 and P3 aneurysms are usually managed by the subtemporal approach. This is a case report of rupture saccular aneurysm of posterior cerebral artery on P2P segment. The authors show the surgical steps of these rare aneurysms with an illustrative case.

Combined surgical and endovascular management of a giant fusiform PCA aneurysm in a pediatric patient. A case report

Treatment of intracranial giant aneurysms presents is challenging. In the case of pediatric giant aneurysm, more challenges arise. We describe our experience with a 17-year-old pediatric patient who presented with severe headache. She was diagnosed as having a giant fusiform aneurysm at the right P1-P2-Pcom junction. The aneurysm was treated with superficial temporal artery-posterior cerebral artery bypass and subsequent coil embolization of the aneurysm with parent artery occlusion. The patient had an excellent outcome at one-year follow-up. Our case suggests a combined approach of surgical and endovascular management may yield a better outcome than surgery or endovascular management alone in the treatment of pediatric giant aneurysm.

Distal superficial temporal artery to proximal posterior cerebral artery bypass by posterior oblique transzygomatic subtemporal approach

This article investigates the possibility for the distal superficial temporal artery (STA) to proximal posterior cerebral artery (PCA) direct bypass by subtemporal oblique posterior transzygomatic approach. Five adult cadaveric specimens were dissected. Cadeveric dissection protocol was approved by the Research Ethics Committee. A preauricular vertical skin incision was made, the trunk of STA was identified, and bifurcation, frontal, and parietal branches of the STA were followed distally. Posterior zygomatic arch osteotomy and microcraniotomy were then performed, and the dura was opened. The temporal lobe was retracted, interpeduncular and ambient cisterns were opened, and the P2 segment of the PCA was exposed. Parietal branch of STA and P2 segment of the PCA was anastomosed. The average length of the transected STA from the bifurcation and the zygomatic arch were 47.3 ± 2.1 mm and 71.4 ± 2.3 mm, respectively. The mean calibers of the parietal and frontal branch of the STA at this distance were 1.6 ± 0.1 and 1.4 ± 0.2, respectively. The mean diameter of the P2 was 2.1 ± 0.2 mm. Because of the calibers of the parietal branch of the STA and proximal PCA are over 1.5 mm and 2.0 mm, respectively, this direct end-to-side bypass technique may be a reasonable alternative in suitable cases.