The evolution of cerebral revascularization surgery

[EC-IC bypass for occlusion of the internal carotid artery]

BACKGROUND

There are barely any alternative treatment options to the drug treatment of hemodynamically caused cerebral ischemia, as in occlusion of the internal carotid artery.

OBJECTIVE

For secondary prevention of an ischemic stroke due to carotid occlusion and hemodynamic instability, extracranial-intracranial (EC-IC) bypass surgery can be an important option in selected patients.

MATERIAL AND METHODS

The development, study situation, indications and surgical technique for placement of an EC-IC bypass in cases of occlusion of the internal carotid artery are presented.

RESULTS

With appropriate expertise and strict selection of patients, the placement of an EC-IC bypass enables stabilization of cerebral perfusion with a low rate of complications.

CONCLUSION

The study situation is controversially discussed; nevertheless, surgical treatment in a specialized neurovascular center should at least be considered.

A Practical Guide to Train the Side-to-side Anastomosis: Tips, Tricks and Technical Nuances

BACKGROUND

Microanastomosis presents a challenge in neurosurgical procedures, requiring specialized skills. Regular practice outside the operating room is crucial. This study aims to provide a detailed description of the side-to-side anastomosis technique and analyze its advantages in preventing failures compared with other variations.

METHODS

We examined the technique, characteristics, and outcomes of side-to-side bypass procedures for complex aneurysms in the anterior cerebral artery territory at our institution over the past decade. We compared our technique with those described in the literature by other groups.

RESULTS

The Far East Neurosurgical Institute (FENI) technique was used in 15 patients, with 17 side-to-side anastomoses performed. The average anastomosis time was 27.5 minutes, with 100% patency in follow-up. Our technique demonstrated safety and effectiveness in treating intracranial aneurysms, yielding satisfactory short- and long-term functionality outcomes. We highlight the importance of maintaining a curvilinear arteriotomy shape, at least 3 times the diameter of the artery, and utilizing an interrupted suturing technique on the anterior wall.

CONCLUSIONS

This paper presents the first comprehensive description of the side-to-side anastomosis technique, supported with images and videos for training and replicability. Our technique enhances flow dynamics and reduces the risk of acute thrombus formation. Training in simulators and microsurgery practice centers outside the operating room is essential for acquiring and refining microsurgical skills.

Two-Stage Pulsatile Human Placenta Model for Microvascular Anastomosis Training in Neurosurgery

OBJECTIVE

The development of microsurgical skills is crucial for neurosurgical education. The human placenta is a promising model for practicing vascular anastomosis due to its similarities with brain vessels. We propose a 2-stage model for training in extracranial-to-intracranial anastomosis using the placenta.

METHODS

Initially, we propose practicing anastomosis in 2 adjacent placentas. Once successful, the procedure advances to a more challenging configuration that employs a 3-dimensionally printed skull with a window simulating a pterional craniotomy. It is positioned an intracranial placenta and an extracranial one, and the latter has a prominent vessel exposed toward the side of the craniotomy. Both placentas have one artery and vein cannulated in the umbilical cord, and we present an artificial placental circulation system for microvascular training that regulates pulsation and hydrodynamic pressure while keeping veins engorged with a pressurized bag. To verify anastomosis patency, we utilize sodium fluorescein and iodine contrast.

RESULTS

The 2-stage model simulated several aspects of microvascular anastomosis. Our perfusion system allowed for intraoperative adjustments of hydrodynamic pressure and pulsation. Using iodine contrast and fluorescein enabled proper evaluation of anastomosis patency and hydrodynamic features.

CONCLUSIONS

Training in the laboratory is essential for developing microsurgical skills. We have presented a model for microvascular anastomosis with artificial circulation and postoperative imaging evaluation, which is highly beneficial for enhancing the learning curve in microvascular procedures.

Neurovascular Microsurgical Experience Through 3-Dimensional Exoscopy: Case Report and Literature Review

BACKGROUND

The microscope is important in neurosurgery, but it is not exempt from limitations. The exoscope has emerged as an alternative because it offers better 3-dimensional (3D) visualization and better ergonomics. We present our initial experience in vascular pathology using 3D exoscopy at the Dos de Mayo National Hospital to show the viability of the 3D exoscope in vascular microsurgery. We also provide a review of the literature.

METHODS

In this work, the Kinevo 900 exoscope was used in 3 patients with cerebral (2) and spinal (1) vascular pathology. We evaluated the image quality, equipment management, ergonomics, educational utility, and 3D glasses and recorded the characteristics of the cases. We reviewed the experience of other authors as well.

RESULTS

Three patients underwent surgery: 1 occipital cavernoma, 1 cerebral dural fistula, and 1 spinal dural fistula. Excellent 3D visualization with Zeiss Kinevo 900 exoscope (Carl Zeiss, Germany), surgical comfort, and educational utility occurred, and there were no complications.

CONCLUSIONS

Our experience and that of other authors suggests that the 3D exoscope shows excellent visualization, better ergonomics, and an innovative educational experience. Vascular microsurgery can be performed safely and effectively.

From textbook to patient: a practical guide to train the end-to-side microvascular anastomosis

Microvascular anastomosis is one of the most challenging neurosurgical techniques. Mastering this technique allows to perform intracranial bypass with arteries of small caliber usually placed in deep narrow surgical fields. The aim of this paper is to describe step by step end-to-side microanastomosis training method by using polyvinyl alcohol (PVA) hydrogel tubing as it is easily reproducible. The tubing comes in sizes from 0.3 mm to 5 mm and has a texture and consistency similar to real vessels. This is based on the Teishinkai Hospital anastomosis technique. Continuous practice in microvascular anastomosis is of great importance in training vascular neurosurgeon. The PVA hydrogel tubing described in this article are useful and cost-effective material in the training of microvascular anastomosis. This practical guide model is easy to set up for repeated practice, and will contribute to facilitate 'off-the-job' training by young neurosurgeons and the development and maintenance of microsurgical skills in both resident neurosurgeons and experts who wish to master the various levels of anastomosis technique. There is no shortcut to master this technique, only hard work and perseverance.

Extracranial-to-Intracranial Bypass for Distal Internal Carotid Artery and/or Proximal Middle Cerebral Artery Steno-Occlusive Disease: A Case Series of Clinical Outcomes at a Single, High-Volume Cerebrovascular Center

BACKGROUND

Extracranial-to-intracranial (EC-IC) bypass was first described by Yasargil in the 1960s for treatment of symptomatic distal internal carotid artery (ICA) and/or proximal middle cerebral artery (MCA) steno-occlusive disease through direct anastomosis. Subsequent bypass trials failed to demonstrate benefit for overall outcomes and stroke rates compared with best medical therapy. However, the procedure remained in the neurosurgeon's armament, with studies showing benefits in select patient populations. With advancements in technology, patient selection has become more comprehensive.

OBJECTIVE

To provide a contemporary evaluation of EC-IC bypass from our high-volume cerebrovascular center, focusing on associated clinical outcomes.

METHODS

Consecutive patients who underwent direct EC-IC bypass surgeries for symptomatic distal ICA and/or proximal MCA steno-occlusive disease between April 2015 and September 2019 were identified retrospectively. Medical records were reviewed to collect demographics, clinical presentation, computed tomography perfusion imaging findings, transcranial Doppler results, procedure indication, donor vessel types, anastomosis site, bypass patency, periprocedural complications, postprocedural complications, symptom recrudescence, repeat or new interventions, subjective improvements, and modified Rankin Scale scores.

RESULTS

We identified 27 patients who underwent 32 EC-IC bypass procedures. The rate of ipsilateral stroke was 9.4%, with a median follow-up of 8 months (IQR, 4-13 months). Patients experienced a 22.3% improvement in modified Rankin Scale scores, and 70.3% of patients reported subjective improvement and satisfaction at follow-up.

CONCLUSION

Direct EC-IC bypass remains a viable option for revascularization in symptomatic patients with distal ICA and/or proximal MCA steno-occlusive disease.

Complementary Tools in Cerebral Bypass Surgery

Cerebral revascularization surgery has been advanced by the refinement of several adjunctive tools. These tools include perioperative blood thinners, intraoperative spasmolytic agents, electrophysiological monitoring, and methods for assessing bypass patency or marking arteriotomies. Despite the array of options, the proper usage and comparative advantages of different complements in cerebral bypass have not been well-cataloged elsewhere. In this literature review, we describe the appropriate usage, benefits, and limitations of various bypass adjuncts. Understanding these adjuncts can help surgeons ensure that they receive reliable intraoperative information about bypass function and minimize the risk of serious complications. Overall, this review provides a succinct reference for neurosurgeons on various cerebrovascular bypass adjuncts.

Beyond Classic Anastomoses Training Models: Overview of Aneurysm Creation in Rodent Vessel Model

Nowadays, due to the decline in the number of microsurgical clippings for cerebral aneurysms and revascularization procedures, young neurosurgeons have fewer opportunities to participate and train on this type of surgery. Vascular neurosurgery is a demanding subspecialty that requires skills that can only be acquired with technical experience. This background pushes the new generations to be ready for such challenging cases by training hard on different available models, such as synthetic tubes, chicken wings, or placenta vessels. Although many training models for vascular neurosurgery have been described worldwide, one of the best is the rodent vessels model. It offers pulsation, coagulation, and real blood flow conditions in a physiologic atmosphere that mimics perfectly the intracranial human vessels environment, especially in terms of size. However, the current differences in governmental different regulations about the use of living animals in medical experimentation and the social awareness, as well as the lack of financial support, cause more difficulties for neurosurgeons to start with that kind of training. In this review, we describe the tools and techniques as basic steps for vascular microsurgery training by using rodent models, that provide an accurate copy of brain vessels environment under stable conditions. The initial three classical known microanastomoses for neurosurgeons are end-to-end, end-to-side, and side-to-side, but in literature, there have been described other more complex exercises for training and investigation, such as aneurysm models. Although there is still little data available, we aim to summarize and discuss aneurysm's training models and reviewed the current literature on the subject and its applications, including a detailed description of the techniques.

The Exoscope in Neurosurgery: An Overview of the Current Literature of Intraoperative Use in Brain and Spine Surgery

Background: Exoscopes are a safe and effective alternative or adjunct to the existing binocular surgical microscope for brain tumor, skull base surgery, aneurysm clipping and both cervical and lumbar complex spine surgery that probably will open a new era in the field of new tools and techniques in neurosurgery. Methods: A Pubmed and Ovid EMBASE search was performed to identify papers that include surgical experiences with the exoscope in neurosurgery. PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses) were followed. Results: A total of 86 articles and 1711 cases were included and analyzed in this review. Among 86 papers included in this review 74 (86%) were published in the last 5 years. Out of 1711 surgical procedures, 1534 (89.6%) were performed in the operative room, whereas 177 (10.9%) were performed in the laboratory on cadavers. In more detail, 1251 (72.7%) were reported as brain surgeries, whereas 274 (16%) and 9 (0.5%) were reported as spine and peripheral nerve surgeries, respectively. Considering only the clinical series (40 studies and 1328 patients), the overall surgical complication rate was 2.6% during the use of the exoscope. These patients experienced complication profiles similar to those that underwent the same treatments with the OM. The overall switch incidence rate from exoscope to OM during surgery was 5.8%. Conclusions: The exoscope seems to be a safe alternative compared to an operative microscope for the most common brain and spinal procedures, with several advantages that have been reached, such as an easier simplicity of use and a better 3D vision and magnification of the surgical field. Moreover, it offers the opportunity of better interaction with other members of the surgical staff. All these points set the first step for subsequent and short-term changes in the field of neurosurgery and offer new educational possibilities for young neurosurgery and medical students.

Management and prognosis of acute extracranial internal carotid artery occlusion

Acute occlusion of the internal carotid artery is the underlying etiology in 4 to 15% of all ischemic strokes. The clinical presentation varies considerably ranging from asymptomatic occlusion to severe ischemic strokes. Substantial differences in the acute management of acute symptomatic internal carotid artery occlusions (ICAO) exists between centers. Thusly, we comprised a narrative review of the natural course of acute ICAO and of available treatment options [i.v. thrombolysis, endovascular thrombectomy and stenting, bypass between the superficial temporal and the middle cerebral arteries (MCA) and carotid endarterectomy (CEA)]. We found that very few randomized treatment trials have been performed in patients acute symptomatic ICAO. Most evidence stems from case series and observational studies. Especially in older studies the intracranial vessel status has rarely been considered. After revision of these studies we concluded that the mainstay of the acute management of acute symptomatic ICAO is i.v. thrombolysis when applied within the label and in combination with mechanical thrombectomy in case of intracranial large vessel occlusion. In cases without intracranial large vessel occlusion mechanical thrombectomy of acute ICAO is associated with a risk of distal embolization. More research on prognostic parameters is needed to better characterize the risk of decompensation of collateral flow and to better define the time-window of intervention. When mechanical thrombectomy fails or is not available, surgical approaches are an alternative in selected patients.

Extracranial-intracranial bypass approach to cerebral revascularization: a historical perspective

While the majority of cerebral revascularization advancements were made in the last century, it is worth noting the humble beginnings of vascular surgery throughout history to appreciate its progression and application to neurovascular pathology in the modern era. Nearly 5000 years of basic human inquiry into the vasculature and its role in neurological disease has resulted in the complex neurosurgical procedures used today to save and improve lives. This paper explores the story of the extracranial-intracranial approach to cerebral revascularization.

Side-to-Side Superficial Temporal Artery to Middle Cerebral Artery Bypass Technique: Application of Fourth Generation Bypass in a Case of Adult Moyamoya Disease

BACKGROUND

Moyamoya disease (MMD) is a rare cause of cerebral hemorrhage and ischemia. Spontaneous development of collateral supply from the external carotid artery (ECA) may limit the use of donor arteries used in standard direct bypass techniques.

OBJECTIVE

To identify the technical feasibility of side-to-side (S-S) superficial temporal artery to middle cerebral artery (STA-MCA) bypass and demonstrate the application of fourth generational bypass techniques in the treatment of MMD.

METHODS

S-S bypass was performed in order to maintain distal outflow in the donor STA. Fourth generation bypass techniques, including atypical anastomosis construction and intraluminal suturing were utilized.

RESULTS

The novel S-S STA-MCA bypass was performed, with patent flow in both recipient MCA and endogenous ECA-ICA collaterals supplied by the distal STA. Technical nuances, including proper alignment of donor vessel, tension reduction, and S-S anastomosis construction with intraluminal suturing technique are essential for successful bypass. Unique flow properties of this bypass were identified, resulting in flow augmentation to the recipient territory compared to standard end-to-side (E-S) techniques.

CONCLUSION

Fourth generational bypass techniques can be successfully applied to MMD, allowing for novel bypass construction. S-S anastomosis can result in potentially beneficial flow properties compared to standard E-S constructions.

Sternocleidomastoid Encephalomyosynangiosis for Treatment-Resistant Moyamoya Disease

BACKGROUND AND IMPORTANCE

Refractory ischemic symptoms in moyamoya disease are a challenging problem, particularly in situations in which multiple direct and indirect revascularization techniques have already been employed. In addition, revascularization of the parietal lobes is difficult, as this area is a watershed between the middle cerebral artery and posterior cerebral artery distributions.

CLINICAL PRESENTATION

This is the case of a 50-yr-old woman with hemibody sensorimotor deficits, who had previously undergone bilateral arterial bypass and temporalis myosynangiosis. A method for indirect surgical cerebral revascularization is described, utilizing a rotated and tunneled sternocleidomastoid flap. The perfused muscle is approximated to the cortical surface, with adjacent sulci dissected to expose the underlying vasculature. After sternocleidomastoid encephalomyosynangiosis, the patient experienced symptomatic improvement, along with the appearance of new pial collateral vasculature on diagnostic cerebral angiography. Pre- and postoperative dynamic perfusion computed tomography with acetazolamide challenge demonstrate an increase in cerebral blood flow and decrease in mean transit time, as well as improved cerebrovascular reserve.

CONCLUSION

Sternocleidomastoid encephalomyosynangiosis using a tunneled muscle flap is a useful method for revascularization of the parietal and occipital lobes, particularly for refractory moyamoya in cases where a variety of other options have been exhausted.

Microsurgical anatomy of the maxillary artery for extracranial-intracranial bypass in the pterygopalatine segment of the maxillary artery

The extracranial-intracranial (EC-IC) bypass using the maxillary artery (MA) has been successfully completed using a radial artery (RA) graft but the complicated anatomy and narrow exposure make it difficult. The purpose of this article is to define the microsurgical exposure of the MA through the middle fossa and describe the branches, diameter, and length of the MA available for the EC-IC bypass in the sphenopalatine fossa and anterior part of the infratemporal fossa. 5 cadaveric specimens were dissected bilaterally (10 MA dissections) to define the microsurgical anatomy of the MA through an intracranial approach. The exposable branches of the MA at the level of the infratemporal and sphenopalatine fossae were the anterior deep temporal, posterior superior alveolar, and infraorbital arteries. The origin of each branch could be exposed. The available section of the MA for use as a donor vessel is between the origin of the anterior deep temporal artery and the infraorbital artery. The mean exposable length of the MA was 19.4 mm. The mean outer diameter of the donor MA was 3.2 mm. Tension-free EC-IC bypass was possible using a RA graft between the MA and the middle cerebral artery, the MA and the supraclinoid internal carotid artery (ICA), or the MA and the petrous ICA. Exposure of the MA at the infratemporal and sphenopalatine fossae is complicated but provides length and diameter suitable as a donor artery for the EC-IC bypass. Clin. Anat. 31:724-733, 2018. © 2017 Wiley Periodicals, Inc.

Effect of Adventitial Dissection of Superficial Temporal Artery on the Outcome of Superficial Temporal Artery-Middle Cerebral Artery Bypass in Moyamoya Disease

Superficial temporal artery-middle cerebral artery (STA-MCA) has been used for the treatment of occlusive cerebrovascular disease including moyamoya disease. The effect of STA-MCA bypass depends not only on the patency of anastomosis, but also on integrity and functional capacity of the donor artery. In the present prospective study, we investigated the effect of extensive stripping STA adventitia and fasciae on hemodynamic function in STA-MCA bypass of moyamoya disease patients. Twenty patients (n=8 in control group, n=12 in stripping group) of moyamoya disease were subjected to STA-MCA end-to-side direct anastomosis. Perfusion unit (PU) values of the cortex were measured and recorded using a Laser Doppler flowmetry (LDF) for 5 days. Computed tomography perfusion was performed to determine blood flow before and after bypass. No patient experienced significant neurologic deficits associated with neurosurgical complications. LDF demonstrated that adventitial stripping group had higher cerebral blood flow increase than control group. The adventitia stripping group tends to have higher rate of increased cerebral perfusion after bypass than non-stripping group. Furthermore, the ultrasound examination at 3 days after bypass demonstrated that the adventitial stripping group has a tendency of bigger STA and higher peak systolic velocity than control group. Our result suggests that stripping adventitia of STA improves hemodynamics of STA-MCA bypass in moyamoya disease.

Cerebral revascularization: direct versus indirect bypass. Case presentation and review

Since 1985 when the EC-IC bypass study results were published and less procedures were performed for cerebral ischemia, the EC-IC bypass even high or low flow and the IC-IC bypass as flow replacement procedures gain acceptance for many neurosurgical pathologies, from extrinsic and intrinsic tumors requiring large vessels sacrifice to large giant and fusiform aneurysms. In recent years, after the results of Carotid Occlusion Surgery Study (COSS) and the Japanese EC-IC trial published their results the indications for extracranial-intracranial (EC-IC) by-pass expanded, including both extracranial carotid artery occlusive disease and intracranial atherosclerotic disease. The authors make a literature review of the indications for cerebral revascularization, with focus on the direct STA-MCA and indirect (EDAMS) revascularization techniques as a treatment for ischemic stroke. They present two cases of Moyamoya disease one treated with combined approaches and one with indirect approach and discuss the technical skills the surgeon should acquire in order to perform an anastomosis, focusing on the details of STA-MCA bypass, concluding that a combined approach gives better neurological results visible shortly after the surgery.

Changes in computed tomography perfusion parameters after superficial temporal artery to middle cerebral artery bypass: an analysis of 29 cases

Introduction Analysis of computed tomography perfusion (CTP) studies before and after superficial temporal artery to middle cerebral artery (STA-MCA) bypass is warranted to better understand cerebral steno-occlusive pathology. Methods Retrospective review was performed of STA-MCA bypass patients with steno-occlusive disease with CTP before and after surgery. CTP parameters were evaluated for change after STA-MCA bypass. Results A total of 29 hemispheres were bypassed in 23 patients. After STA-MCA bypass, mean transit time (MTT) and time to peak (TTP) improved. When analyzed as a ratio to the contralateral hemisphere, MTT, TTP, and cerebral blood flow (CBF) improved. There was no effect of gender, double vessel versus single vessel bypass, or time until postoperative CTP study to changes in CTP parameters after bypass. Conclusions Blood flow augmentation after STA-MCA bypass may best be assessed by CTP using baseline MTT or TTP and ratios of MTT, TTP, or CBF to the contralateral hemisphere. The failure of cerebrovascular reserve to improve after cerebral bypass may indicate irreversible loss of autoregulation with chronic cerebral vasodilation or the inability of CTP to detect these improvements.