Cerebral revascularization for ischemia, aneurysms, and cranial base tumors

Assessing the Adequacy of Superficial Temporal Artery Blood Flow in Korean Patients Undergoing STA-MCA Anastomosis

OBJECTIVE

Superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis is conducted for flow augmentation. In this study, we measured the STA cut flow of a Korean population and evaluated the relationship between STA cut flow and long-term patency of the bypass.

METHODS

A retrospective study was conducted. Intraoperative measurement of STA flow was conducted using a microvascular flow meter on patients who underwent STA-MCA. After cutting the distal end, the STA flow rate was measured with no resistance and recorded. After finishing anastomosis, STA flow was measured and recorded. The cut flow index was calculated by dividing post anastomosis flow by cut flow in intracranial atherosclerotic stenosis patients.

RESULTS

The median STA cut flow was 35.0 mL/min and the post anastomosis flow was 24.0 mL/min. The cut flow of STA decreased with aging (p=0.027) and increased with diameter (p=0.004). The cut flow showed no correlation with history of hypertension or diabetes mellitus (p=0.713 and p=0.786), but did correlate a positively with history of hyperlipidemia (p=0.004). There were no statistical differences in cut flow, STA diameter, and post anastomosis flow between the frontal and parietal branches (p=0.081, p=0.853, and p=0.990, respectively).

CONCLUSION

The median STA cut flow of a Korean population was 35 mL/min. Upon reviewing previous articles, it appears that there are differences in the STA cut flow between Western and Asian patients.

Clinical effect of high-flow revascularization in microsurgery combined with endoscopic endonasal surgery for skull base tumors with intracranial and extracranial involvement

Background

The objective of the study is to investigate the surgical methods and clinical effects of high-flow revascularization in microsurgery combined with endoscopic endonasal surgery for skull base tumors with intracranial and extracranial involvement.

Methods

The relationships between skull base tumors and internal carotid artery (ICA), tumor location and size, and the extent of tumor invasion were assessed. Preoperative CT perfusion (CTP), magnetic resonance (MR) perfusion-weighted imaging (PWI) (MR-PWI), and digital subtraction angiography (DSA) were performed to evaluate collateral circulation and brain tissue perfusion. Then craniotomy through the fronto-orbitozygomatic approach was performed, based on which four cases received extended middle skull base approach+Dolenc approach + Fukushima bypass type I, and six cases received extended middle skull base approach+Fukushima bypass type III. After surgery, DSA, CT angiogram (CTA), and CTP/PWI were performed to evaluate the patency of the reconstructed vessels and cerebral perfusion, and contrast-enhanced MRI to evaluate the degree of tumor resection. All patients were followed up for 6-12 months.

Results

Among the 10 cases investigated, gross total resection was achieved in 8 cases, subtotal resection in 1 case, and partial resection in 1 case, as confirmed by CT and enhanced MRI. The patency of revascularization vessels was observed using fluorescein angiography during the operation in all patients and via DSA and CTA postoperatively in nine patients. One patient underwent ventilator-assisted ventilation because of respiratory failure and failed to undergo DSA and CTA. Regarding postoperative complications, one patient developed watershed cerebral infarction on the operated side but no sequelae after drug treatment, three patients developed facial numbness, which improved after 3 months, and two patients experienced worsened diplopia. After 6 to 12 months of follow-up on the nine evaluable patients, the Glasgow Outcome Scale (GOS) was 4-5 after surgery. In addition, 6-month follow-up results showed that one patient with clival chondrosarcoma developed recurrence on contrast-enhanced MRI, while no relapse was observed in the other patients.

Conclusion

For skull base tumors with intracranial and extracranial invasion and involving the ICA, revascularization might improve the total resection rate and reduce the recurrence rate and risk of intraoperative bleeding and postoperative ischemia.

Surgical revascularization (bypass surgery) in the treatment of complicated cerebral aneurysms

The aim of surgical treatment of any cerebral aneurysm is to achieve its total exclusion from the bloodstream. Although the progress in the development and implementation of microsurgical and the latest endovascular technologies, in many cases, the treatment of complex cerebral aneurysms is not an easy task. Unsatisfactory results of the exclusion of complicated cerebral aneurysms are due to many factors, for instance: gigantic size, fusiform or dolichoectatic configuration of the cerebral aneurysm, the presence of atherosclerotic changes, anatomical features of the departure of functionally important arteries directly from the cerebral aneurysm. Such cerebral aneurysms are quite problematic both for microsurgical remodeling clipping and for endovascular exclusion. At the current stage, the introduction and use of the microanastomosis technique provides additional options and expands the possibilities of surgical treatment of complex cerebral aneurysms.Objective ‒ to analyze the possibilities and results of surgical treatment of complicated cerebral aneurysms using the technique of surgical revascularization (bypass surgery).Materials and methods. An analysis of the results of the examination and surgical treatment of 16 patients with complicated cerebral aneurysms for the period from 2016 to 2020, who were treated and operated on in the emergency vascular neurosurgery department with the X-ray operating department Romodanov Institute of Neurosurgery of NAMS of Ukraine. All patients diagnosed with complicated cerebral aneurysms had gigantic sizes. All cases of surgical intervention included placement of extra-intracranial microanastomosis or intra-intracranial anastomosis, sometimes a combination of it, to ensure normal blood supply to the vessel of complicated cerebral aneurysm that were planned to be devascularized. In 14 observations, one-time anastomosis and exclusion of complicated cerebral aneurysms were performed. In 2 observations, the first stage was an anastomosis without exclusion of the complicated cerebral aneurysms due to insufficient vascularization of the distal arterial branch for deconstructive exclusion of aneurysm.Results. Satisfactory results of surgical treatment (grade 1 and 2 of Modified Rankin Scale (MRS)) in the general group of patients were observed in 13 (81 %) patients with complicated cerebral aneurysms. Unsatisfactory results of surgical treatment occurred in 3 (19 %) observations. Profound disability (MRS grade 5) as a result of surgical treatment was recorded in 1 (6 %) patient. Cases that ended fatally occurred in 2 (13 %) observations of the total group of patients. In the group of patients with surgical revascularization and excluded complicated cerebral aneurysms, satisfactory results were observed in 13 (92.9 %) patients. Fatal results of surgical treatment were recorded in 2 patients with a hemorrhagic course of complicated cerebral aneurysms, in which surgical revascularization was performed as first stage and scheduled removal of complicated cerebral aneurysms was planned.Conclusions. The introduction and use of the microanastomosis technique expands the possibilities of surgical treatment of complicated cerebral aneurysms. Revascularization surgical interventions are highly effective in the prevention of ischemic complications when complicated cerebral aneurysms are excluded. Recommendations (indications) for revascularization should be considered in impossibility and high risks of ischemic complications during remodeling clipping or endovascular exclusion of complicated cerebral aneurysms.

Extra-intracranial bypass surgery using the orifice of maxillary artery in a patient with middle cerebral artery aneurysm. Case report and literature review

OBJECTIVE

To present the technique of extra-intracranial bypass surgery using the orifice of maxillary artery bypass, to evaluate the advantages and disadvantages of this and alternative revascularization options.

MATERIAL AND METHODS

Radial artery graft harvesting was performed at the 1st stage. Simultaneously, the second team of surgeons performed a combined (submandibular and anterior) access to the donor artery (mandibular segment of maxillary artery behind the ramus of the mandible). Craniotomy and mobilization of potential recipient arteries (M2-M3 segments of the middle cerebral artery) were performed at the 2nd stage. Distal anastomosis in end-to-side fashion was formed with M3 segment of the middle cerebral artery. At the 3rd stage, radial artery was passed through a subcutaneous tunnel in zygomatic region. The orifice of maxillary artery was resected together with distal external carotid artery (ECA) and orifice of superficial temporal artery. After transposition of ECA and orifice of maxillary artery, proximal end-to-end anastomosis was performed with radial artery. After that, the main surgical stage was performed, i.e. exclusion of M3 segment of the middle cerebral artery together with aneurysm.

RESULTS

Harvesting of mandibular segment of the maxillary artery as a donor vessel reduces the length of bypass graft to 12-14 cm since this branch is localized close to the skull base. You can also form optimal proximal end-to-end anastomosis for intracranial redirecting blood flow maxillary artery.

CONCLUSION

The described method makes it possible to form anastomosis with a short bypass graft and reduce the risk of thrombosis. This procedure is effective for cerebral bypass in patients with skull base tumors, complex aneurysms, and occlusive-stenotic lesions of carotid arteries.

Resection of the internal carotid artery in selected patients affected by cancer of the skull base

Invasion of the internal carotid artery (ICA) has been historically considered a criterion of non-resectability of skull base cancer (SBC). Patients affected by SBC who underwent surgery including resection of ICA at two tertiary institutions were included. Demographics, oncologic, and surgical information, complications, and survival outcomes were retrospectively reviewed. Survival outcomes were calculated. Ten patients were included. Three surgical approaches (transnasal endoscopic, transorbital, and transpetrosal) were employed to resect the invaded/abutted tract(s) of the ICA. All patients underwent ICA temporary balloon occlusion test. In two patients, an extracranial-to-intracranial arterial bypass was harvested. Major neuromorbidity was observed in two patients. Perioperative mortality of the series was 10.0%. Mean overall survival was 27.2 months, with 2-year overall and progression-free survival rate of 88.9%. ICA resection is feasible as part of the ablation performed for very advanced SBCs. Survival outcomes are acceptable in adequately selected patients.

When Everything Revolves Around Internal Carotid Artery: Analysis of Different Management Strategies in Patients With Very Advanced Cancer Involving the Skull Base

Internal or common carotid artery encasement (CAE) is observed in almost 2-7% of head and neck cancers (HNC) and designates the tumor with the T4b category. This clinical scenario is associated with a dismal prognosis, owing to the risk for thrombosis and bleeding that usually characterizes such an advanced cancer. Standardized radiological criteria to infer invasion of the carotid artery are lacking. Complete surgical resection in the context of a multimodality treatment is supposed to offer the greatest chances of cure. Surgery can either be carotid-sparing or include carotidectomy. Data on probability of cerebrovascular and non-cerebrovascular complications, risk of carotid blowout, poor oncologic outcomes, and less-than-certain efficacy of diagnostic and interventional preventive procedures against cerebral infarction make it difficult to define surgery as the recommended option among other therapeutic strategies. Non-surgical therapies based on radiation therapy possibly combined with chemotherapy are more frequently employed in HNC with CAE. In this context, carotid blowout is the most feared complication, and its probability increases with tumor stage and cumulative radiation dose received by the vessel. The use of highly conformal radiotherapies such as intensity-modulated particle therapy might substantially improve the manageability of HNC with CAE by possibly reducing the risk of late sequalae. Despite evidence is frail, it appears logical that a case-by-case evaluation through multidisciplinary decision making between head and neck surgeons, radiation oncologists, medical oncologists, diagnostic and interventional radiologists, and vascular surgeons are of paramount value to offer the best therapeutic solution to patients affected by HNC with CAE.

Can Evoked Potential Changes during the Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery Predict Postoperative Improvement of Cerebral Perfusion and Functional Status?

BACKGROUND

We investigated evoked potential (EP) changes during superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery and their correlations with imaging and clinical findings postoperatively.

METHODS

This retrospective study included patients who underwent STA-MCA bypass surgery due to ischemic stroke with large artery occlusion (MB group). Patients who underwent unruptured MCA aneurysm clipping were enrolled in the control group (MC group). Median and tibial somatosensory evoked potentials (SSEP), and motor evoked potentials recorded from the abductor pollicis brevis (APB-MEP) and abductor hallucis (AH-MEP) were measured intraoperatively. Modified Rankin scale (mRS) and perfusion-weighted imaging (PWI) related variables, i.e., mean transit time (MTT) and time to peak (TTP), were assessed.

RESULTS

Δmedian SSEP, ΔAPB-MEP, and ΔAH-MEP were significantly higher in the MB group than in the MC group (p = 0.027, p = 0.006, and p = 0.015, respectively). APB-MEP and AH-MEP amplitudes were significantly increased at the final measurement (p = 0.010 and p < 0.001, respectively). The ΔTTP asymmetry index was moderately correlated with ΔAPB-MEP (r = 0.573, p = 0.005) and ΔAH-MEP (r = 0.617, p = 0.002). ΔAPB-MEP was moderately correlated with ΔMTT (r = 0.429, p = 0.047) and ΔmRS at 1 month (r = 0.514, p = 0.015).

CONCLUSIONS

MEP improvement during STA-MCA bypass surgery was partially correlated with PWI and mRS and could reflect the recovery in cerebral perfusion.

When is a multidisciplinary surgical approach required in sinonasal tumours with cranial involvement?

The term “sinonasal tumours” includes a large spectrum of diseases, which are characterized by heterogeneous biological behavior and prognosis, and located in a critical anatomic area. Diagnosis and treatment of sinonasal tumours require the contribution of different disciplines. A narrative review was performed to highlight the role of surgeons in contributing to a multidisciplinary approach to sinonasal tumours. Diagnosis and staging of sinonasal tumours is challenging and requires collaboration between surgeons, radiologists, and pathologists. The identification and management of critical extensions (orbital or intracranial encroachment, vascular abutment or encasement) is fundamental for successful treatment. Most cases of advanced sinonasal tumours can undergo surgical intervention by an adequately trained otorhinolaryngological team. The contribution of neurosurgeons and oculoplastic surgeons is required in selected scenarios. In rare circumstances, multidisciplinary reconstructive strategies can be indicated for complex tissue defects. Furthermore, a multidisciplinary approach is pivotal in the management of perioperative complications. While surgery remains the mainstay of treatment, the role of non-surgical adjuvant or even exclusive treatments is constantly expanding.

Trends in Literature on Cerebral Bypass Surgery: A Systematic Review

INTRODUCTION

Ever since the beginning of cerebral bypass surgery, the role of the bypass has been debated and indications have changed over the last 5 decades. This systematic literature research analysed all clinical studies on cerebral bypass that have been published from January 1959 to January 2020 for their year of publication, country of origin, citation index, role of and indication for bypass, bypass technique, revascularized territory, flow capacity, and title (for word cloud analysis per decade).

METHODS

A systematic literature research was conducted using PubMed, Web of Science, EMBASE, and SCOPUS databases. All studies that have been published until January 1, 2020, were included.

RESULTS

Of 6,013 identified studies, 2,585 were included in the analysis. Of these, n = 1,734 (67%) studies addressed flow-augmentation bypass and n = 701 (27%) addressed flow-preservation bypass. The most common indication reported for flow augmentation is moyamoya (n = 877, 51%), followed by atherosclerotic steno-occlusive disease (n = 753, 43%). For flow preservation, the most common indication is studies reporting on cerebral aneurysm surgery (n = 659, 94%). The increasing popularity of reporting on these bypass operations almost came to an end with the FDA approval of flow diverters for aneurysm treatment in 2011. Japan is the country with the most bypass studies (cumulatively published 933 articles), followed by the USA (630 articles) and China (232 articles).

DISCUSSION/CONCLUSION

Clinical studies on cerebral bypass surgery have become increasingly popular in the past decades. Since the introduction of moyamoya as a distinct pathologic entity, Asian countries in particular have a very active community regarding this disease, with an increasing number of articles published every year. Studies on bypass for chronic steno-occlusive disease peaked in the 1980s but have remained the main focus of bypass research, particularly in many European departments. The number of reports published on these bypass operations significantly decreased after the FDA approval of flow diverters for aneurysm treatment in 2011.

Ruptured blood blister like aneurysm: does the best therapeutic option really exist?

Our study aimed to evaluate the outcome of patients with ruptured blood-blister like aneurysm (BBLA) in our institution by comparing microsurgical selective treatment to endovascular treatment using flow-diverter stent (FD). Our study included 18 consecutive patients treated for BBLA between 2004 and 2020. Until 2014, microsurgery was preferred in all patients with BBLA (n = 10). Significant postoperative morbi-mortality was recorded at this time and led us to change therapeutic strategy and to favor FD as first-line treatment in all patients (n = 8). Postprocedural complications and BBLA occlusion were recorded. High WFNS score (> 2) was noted in 6 patients of microsurgical group and in 2 of endovascular group. In microsurgical group, ischemic lesions were noted in 6 patients and led to death in 3 patients. Immediate BBLA occlusion was obtained in all patients. Favorable outcome after 3 months (mRS < 3) was recorded in 4 of the 7 survivors. In endovascular group, ischemic lesions were noted in 4 patients. One patient died from early postprocedural BBLA rebleeding. Scarpa hematoma was noted in 3 patients with surgical evacuation in 1. Persistent BBLA at 3 months was recorded in 4 patients without rebleeding, but further FD was required in 1 with growing BBLA. Favorable outcome was noted in 6 of the 7 survivors. Although, rate of morbi-mortality appear lower in patients treated with FD, neurological presentation was better and BBLA diagnosis remains questionable in this group. Moreover, persistent BBLA imaging with potential risk of rebleeding after FD deserves to be discussed.

Preoperatively estimated graft flow rate contributes to the improvement of hemodynamics in revascularization for Moyamoya disease

OBJECTIVES

Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass operation is an effective treatment for patients with Moyamoya disease, and the hemodynamic parameters are reported to be improved after operation. However, there is no report concerning hemodynamic changes from the viewpoint of the preoperative anatomical structure of grafts. In this study, we evaluated the correlation between the preoperatively estimated blood flow of the graft obtained through image-based computational fluid dynamics (CFD) analysis and the hemodynamic changes in the acute phase after revascularization.

MATERIALS AND METHODS

A total of 30 hemispheric sides of 23 patients were examined. The blood flow, that is, flow rate (FR) of the STA branches that were anastomosed to the MCA was evaluated using CFD analysis based on computed tomography (CT) angiography imaging data. The correlations between the FR and the hemodynamic changes in the acute phase after revascularization obtained through CT perfusion were assessed.

RESULTS

The preoperatively estimated FR of the graft was moderately correlated with the changes in the mean transit time significantly and weakly correlated with those in the cerebral blood flow and cerebral blood volume. In addition, the FR was strongly correlated with age and the diameter of the STA from the origin to the bifurcation.

CONCLUSION

The preoperatively estimated FR of the graft obtained through image-based CFD analysis contributed to the improvement of the mean transit time after revascularization. Because the FR of the graft was associated with the diameter of the STA, the size of the STA might be an important factor in postoperative hemodynamic changes. This might lead to the risk assessment of acute drastic hemodynamic changes as cerebral hyperperfusion, and consequently, better surgical outcomes might be expected.

Effects of dobutamine and phenylephrine on cerebral perfusion in patients undergoing cerebral bypass surgery: a randomised crossover trial

Background

Patients undergoing cerebral bypass surgery are prone to cerebral hypoperfusion. Currently, arterial blood pressure is often increased with vasopressors to prevent cerebral ischaemia. However, this might cause vasoconstriction of the graft and cerebral vasculature and decrease perfusion. We hypothesised that cardiac output, rather than arterial blood pressure, is essential for adequate perfusion and aimed to determine whether dobutamine administration resulted in greater graft perfusion than phenylephrine administration.

Methods

This randomised crossover study included 10 adult patients undergoing cerebral bypass surgery. Intraoperatively, patients randomly and sequentially received dobutamine to increase cardiac index or phenylephrine to increase mean arterial pressure (MAP). An increase of >10% in cardiac index or >10% in MAP was targeted, respectively. Before both interventions, a reference phase was implemented. The primary outcome was the absolute difference in graft flow between the reference and intervention phase. We compared the absolute flow difference between each intervention and constructed a random-effect linear regression model to explore treatment and carry-over effects.

Results

Graft flow increased with a median of 4.1 (inter-quartile range [IQR], 1.7–12.0] ml min⁻¹) after dobutamine administration and 3.6 [IQR, 1.3–7.8] ml min⁻¹ after phenylephrine administration (difference –0.6 ml min⁻¹; 95% confidence interval [CI], –14.5 to 5.3; P=0.441). There was no treatment effect (0.9 ml min⁻¹; 95% CI, 0.0–20.1; P=0.944) and no carry-over effect.

Conclusions

Both dobutamine and phenylephrine increased graft flow during cerebral bypass surgery, without a preference for one method over the other.

Clinical trial registration

Netherlands Trial Register, NL7077 (https://www.trialregister.nl/trial/7077).

[Analysis of local hemodynamics in complex aneurysms: an effect of the vessel arising from the dome or the neck]

BACKGROUND

Assessment of rupture risk for intracranial aneurysms (IA) is a particular challenge in cases of so-called complex aneurysms due to their variable morphometric characteristics. Arterial branch arising from the dome or the neck of IA is one of the least explored features of complex aneurysms. The methods of computational fluid dynamics may be valuable to determine the influence of arterial branches of IA on local hemodynamics.

OBJECTIVE

To analyze local hemodynamics in IA with arterial branch arising from the cupola or the neck depending on the structure of the aneurysm and blood flow rate in the parent vessel.

MATERIAL AND METHODS

CT angiography data of 4 patients with IA were estimated in this study. Modifications of the baseline 3D models of the aneurysms resulted 12 patient-specific models included into analysis. Hemodynamic calculations were made by using of ANSYS Workbench 19 software package.

RESULTS

Wall shear stress (WSS) was characterized by the most significant variability, especially in case of sidewall aneurysms. Small cross-sectional area of additional branch in relation to the neck of IA was not followed by considerable changes of blood flow patterns inside IA after «virtual» removal of the vessel. Otherwise, the intensity of flows was drastically reduced. Simulation of high inlet flows demonstrated substantial variation of WSS in the area of jet.

CONCLUSION

Additional arterial branch arising from the dome or the neck of IA significantly influences local hemodynamics. This influence depends on the localization of IA in relation to the parent vessel and the diameter of additional arterial branch.

Carotid artery occlusion and revascularization in the management of meningioma

As the carotid artery courses through the skull base and into the subarachnoid space, it lies in close proximity to regions notorious for meningioma growth. Although infrequent, the growth of these tumors can compromise blood flow through the artery, putting the downstream territory at risk for stroke. In other scenarios, removal of these tumors sometimes requires planning to accomplish both tumor removal and revascularization in the same procedure when then the tumor invades the artery. Since revascularization (bypass surgery) is best performed on a nonemergent basis, it should be given consideration in the preoperative setting. Crisis situations related to intraoperative iatrogenic injury are managed methodically by determining the site of vessel injury and then deciding whether a primary repair or bypass procedure is necessary. The mainstays of revascularization procedures of the carotid artery include flow augmentation and flow replacement, with the superficial temporal artery and external carotid artery being the donor sites, respectively. Although tumor control or cure can be accomplished with surgical, radiosurgical, or combined methods, attention to vascular structures and ensuring blood flow preservation as part of the treatment plan is an important tenet in meningioma surgery.

Cerebral revascularization for the management of complex intracranial aneurysms: a single-center experience

OBJECTIVE

Because simple intracranial aneurysms (IAs) are increasingly treated endovascularly, neurovascular surgery has become focused on complex IAs that may require deconstructive aneurysm therapy with concomitant surgical bypass. The authors describe the decision-making process concerning cerebral revascularization and present outcomes that were achieved in a large case series of complex IAs managed with cerebral revascularization and parent artery occlusion.

METHODS

The authors retrospectively reviewed the medical records, including neuroimaging studies, operative reports, and follow-up clinic notes, of all patients who were treated at the National Brain Aneurysm Center between July 1997 and June 2015 using cerebral revascularization as part of the management of an IA. They recorded the location, rupture status, and size of each IA, as well as neurological outcome using the modified Rankin Scale (mRS), aneurysm and bypass status at follow-up, and morbidity and mortality.

RESULTS

The authors identified 126 patients who underwent revascularization surgery for 126 complex, atheromatous, calcified, or previously coiled aneurysms. Ninety-seven lesions (77.0%) were unruptured, and 99 (78.6%) were located in the anterior circulation. Aneurysm size was giant (≥ 25 mm) in 101 patients, large (10-24 mm) in 9, and small (≤ 9 mm) in 16 patients. Eighty-four low-flow bypasses were performed in 83 patients (65.9%). High-flow bypass was performed in 32 patients (25.4%). Eleven patients (8.7%) underwent in situ or intracranial-intracranial bypasses. Major morbidity (mRS score 4 or 5) occurred in 2 (2.4%) low-flow cases and 3 (9.1%) high-flow cases. Mortality occurred in 2 (2.4%) low-flow cases and 2 (6.1%) high-flow cases. At the 12-month follow-up, 83 (98.8%) low-flow and 30 (93.8%) high-flow bypasses were patent. Seventy-five patients (90.4%) undergoing low-flow and 28 (84.8%) high-flow bypasses had an mRS score ≤ 2. There were no statistically significant differences in patency rates or complications between low- and high-flow bypasses.

CONCLUSIONS

When treating challenging and complex IAs, incorporating revascularization strategies into the surgical repertoire may contribute to achieving favorable outcomes. In our series, low-flow bypass combined with isolated proximal or distal parent artery occlusion was associated with a low rate of ischemic complications while providing good long-term aneurysm control, potentially supporting its wider utilization in this setting. The authors suggest that consideration should be given to managing complex IAs at high-volume centers that offer a multidisciplinary team approach and the full spectrum of surgical and endovascular treatment options to optimize patient outcomes.

Superficial Temporal Artery: Middle Cerebral Artery Bypass, Our Series of 20 Cases, Surgical Technique and Indications with Illustrative Cases

The first extracranial-intracranial (EC-IC) bypass surgery was performed by professor Yasargil in 1967 since then this procedure has been widely used in vascular neurosurgery and sometimes, in tumors excision when a vascular sacrifice is necessary. In this article, we will illustrate the surgical technique of the superficial temporal artery-middle cerebral artery (STA-MCA) bypass with two cases; a 59-year-old male and 64-year-old female who presented with an occlusion of the MCA. The male presented also with a posterior communicating artery-IC aneurysm which was clipped in the same sitting. We also studied in this paper a series of 20 patients operated in Banbuntane Hotokukai Hospital, Fujita Health University, for which a low-flow STA-MCA anastomosis was done for steno-occlusive disease or moyamoya disease. In Banbuntane Hotokukai Hospital, Fujita Health University, 20 patients were operated since 2015, 12 patients were male. Five patients presented with moyamoya disease, while 15 patients presented with vascular steno-occlusive disease. The steno-occlusion was found in internal carotid artery in nine patients. The patients were divided into two categories (steno-occlusive disease and moyamoya). STA-MCA bypass is now one of the basic techniques to master in vascular neurosurgery. It requires to perform the anastomosis correctly within the permissible time. The goal is to have a long-term patency for the anastomosed vessel.

“BONNET” BYPASS IN BRAIN REVASCULARISATION

The article describes the “bonnet” bypass, the type of extracranial-intracranial bypass. This technique is performed when ipsilateral arteries can’t be used as a donor when cerebral revascularization is required. The literature was analyzed and three main techniques of “bonnet” have been defined. The indications for performing “bonnet” bypass are determined, and the disadvantages are indicated. Alternative methods of revascularization are presented and technical details of graft protection are described. The “bonnet” bypass is a rare and laborious technique of cerebral revascularisation. However, it is an alternative and effective method of treatment to prevent serious ischemic disorders.

Protective STA-MCA bypass to prevent brain ischemia during high-flow bypass surgery: case series of 10 patients

BACKGROUND

High-flow extracranial-intracranial bypass is associated with a significant risk of ischemic stroke. The goal of this study is to evaluate the effectiveness of STA-MCA bypass preceding a high-flow bypass as a means of protecting the brain from ischemia during the high-flow bypass anastomosis in patients with otherwise untreatable aneurysms.

MATERIALS AND METHOD

This prospective study included 10 consecutive patients treated for complex/giant aneurysm using a previous combined STA-MCA bypass and high-flow EC-IC bypass between June 2016 and January 2018 when classical endovascular or microsurgical exclusion was estimated too risky. Early cranial Doppler, MRI, CT scan, and conventional angiography were performed in each patient to confirm patency of bypasses, measure flow in the anastomoses, detect any ischemic lesions, and evaluate exclusion of the aneurysm.

RESULTS

The mean age at treatment was 55 years (range 34 to 67). The mean time of microsurgical procedure was 11 h (range 9 to 12). In all patients, the high-flow bypass was patent intraoperatively and complete occlusion of aneurysm was obtained. No ischemic lesions were noted on early MRI. One patient died from a large hemispheric infarction related to a common carotid artery dissection 10 days after the microsurgical procedure and immediate postoperative epidural hematoma was noted in one other patient.

CONCLUSION

In this study, we described the use of a protective STA-MCA bypass, performed prior to the high-flow bypass, in order to reduce the risk of perioperative ischemic lesions without increasing the morbidity of the surgical procedure. This treatment paradigm was feasible in all ten patients without complications related to the STA-MCA anastomosis.

STA-MCA bypass following sphenoid wing meningioma resection: A case report

•

There were a few cases of skull base tumors requiring vessel revascularization. This is the first clinical report on this issue in Vietnam.

•

Most of the vessel revascularization cases were meningiomas.

•

Saphenous vein graft (SVGs) was the most commonly reported graft, followed by radial artery graft (RAGs).

•

STA-MCA bypass was a safe and helpful choice, especially the collateral vessels were present and the need for blood flow augmentation was minimal.

Introduction

Sphenoid meningioma engulfed cerebral arteries has always been a challenge. To achieve a gross total resection, vessel sacrifice may be unavoidable.

Presentation of case

A 22-year-old man with a history of head trauma a week ago complained of a headache for one week. On examination, he was alert, denied paralysis and cranial nerves palsies. Preoperative MRI showed a hypervascular left sphenoid wing meningioma embedding left internal carotid artery and proximal segment of the middle cerebral artery. In operation, a branch of the MCA was divided when dissecting the tumor. The MCA was clipped but was still difficult to dissect vessel ends in the Sylvian fissure. We decided to extend craniotomy and did superficial temporal artery to M4 segment of MCA bypass. Then, the patient was resuscitated in surgical high dependency unit for 3 days. Surgical outcome in one year postoperative was good with KPS 90 out of 100 points and no neurological deficits. On postoperative MRA, STA-MCA bypass shown acceptable flow.

Discussion

There were a few cases of skull base tumors requiring vessel revascularization. Most of the revascularization cases were meningiomas. Saphenous vein graft (SVGs) was the most commonly reported graft, followed by radial artery graft (RAGs). In case of difficulty in dissecting the vessel ends due to the tumor infiltration, STA-MCA bypass was a safe and helpful choice, especially the collateral vessels were present and the need for blood flow augmentation was minimal.

Conclusion

STA-MCA bypass was effective surgical management for MCA injury in sphenoid wing meningioma resection.

A novel, low-cost, reusable, high-fidelity neurosurgical training simulator for cerebrovascular bypass surgery

OBJECTIVE

Cerebrovascular bypass surgery is a challenging yet important neurosurgical procedure that is performed to restore circulation in the treatment of carotid occlusive diseases, giant/complex aneurysms, and skull base tumors. It requires advanced microsurgical skills and dedicated training in microsurgical techniques. Most available training tools, however, either lack the realism of the actual bypass surgery (e.g., artificial vessel, chicken wing models) or require special facilities and regulations (e.g., cadaver, live animal, placenta models). The aim of the present study was to design a readily accessible, realistic, easy-to-build, reusable, and high-fidelity simulator to train neurosurgeons or trainees on vascular anastomosis techniques even in the operating room.

METHODS

The authors used an anatomical skull and brain model, artificial vessels, and a water pump to simulate both extracranial and intracranial circulations. They demonstrated the step-by-step preparation of the bypass simulator using readily available and affordable equipment and consumables.

RESULTS

All necessary steps of a superficial temporal artery-middle cerebral artery bypass surgery (from skin opening to skin closure) were performed on the simulator under a surgical microscope. The simulator was used by both experienced neurosurgeons and trainees. Feedback survey results from the participants of the microsurgery course suggested that the model is superior to existing microanastomosis training kits in simulating real surgery conditions (e.g., depth, blood flow, anatomical constraints) and holds promise for widespread use in neurosurgical training.

CONCLUSIONS

With no requirement for specialized laboratory facilities and regulations, this novel, low-cost, reusable, high-fidelity simulator can be readily constructed and used for neurosurgical training with various scenarios and modifications.

Revascularization of the anterior cerebral artery by Y-shaped superficial temporal artery interposition graft for the treatment of a de novo aneurysm arising at the site of A3-A3 bypass: technical case report

The most frequently used option to reconstruct the anterior cerebral artery (ACA) is an ACA-ACA side-to-side anastomosis. The long-term outcome and complications of this technique are unclear. The authors report a case of a de novo aneurysm arising at the site of A3-A3 anastomosis. A 53-year-old woman underwent A3-A3 side-to-side anastomosis for the treatment of a ruptured right A2 dissecting aneurysm. At 44 months after surgery, a de novo aneurysm developed at the site of anastomosis. The aneurysm developed in the front wall of the anastomosis site, and projected to the anterosuperior direction. A computational fluid dynamics (CFD) study showed the localized region with high wall shear stress coincident with the pulsation in the front wall of the anastomosis site, where the aneurysm developed. A Y-shaped superficial temporal artery (STA) interposition graft was used successfully to reconstruct both ACAs, and then the aneurysm was trapped. To the authors' knowledge, this is the first case of a de novo aneurysm that developed at the site of an ACA-ACA side-to-side anastomosis. A CFD study showed that hemodynamic stress might be an underlying cause of the aneurysm formation. A Y-shaped STA interposition graft is a useful option to treat this aneurysm. Long-term follow-up is necessary to detect this rare complication after ACA-ACA anastomosis.

Double-barrel STA to proximal MCA bypass and proximal parent artery occlusion for a fusiform superior clinoidal ICA aneurysm

BACKGROUND

Blood flow replacement and parent artery occlusion are alternative treatments of complex fusiform superior clinoidal ICA aneurysms. While double-barrel STA to proximal MCA bypass is a conventional approach among these reported bypass algorithms, its technical details remain underexplored.

METHOD

We have applied the double-barrel STA to proximal MCA bypass and parent artery occlusion to treat a 45-year-old female patient with a right fusiform superior clinoidal ICA aneurysm. The technical nuances of this approach are reported.

CONCLUSION

We show that double-barrel STA to proximal MCA bypass and proximal parent artery occlusion can be alternative treatments of complex fusiform superior clinoidal ICA aneurysms.

Flow diversion versus parent artery occlusion with bypass in the treatment of complex intracranial aneurysms: Immediate and short-term outcomes of the randomized trial

OBJECTIVE

We performed prospective randomized comparison of clinical and surgical outcomes of flow diversion versus PVO and bypass in patients with complex anterior circulation aneurysms.

PATIENTS AND METHODS

Open, prospective, randomized, parallel group, multicenter study of complex intracranial aneurysms treatment was conducted. Patients with complex intracranial aneurysms of anterior circulation with neck is more than 4 mm wide, dome/neck ratio is equal or less than 2:1, which is suitable for flow diversion and occlusion with bypass were included in the study. A total of 111 potential participants were enrolled since March 2015. Additional propensity score matching was performed with 40 patients in each group selected for analysis.

RESULTS

39 out of 40 patients (97.5%) from matched FD group reached good clinical outcome. In the matched bypass group acceptable outcome was achieved in 32 (80%) out of 40 patients (difference between groups p = 0.029). The morbidity and mortality rates were 15% and 5%, respectively. Difference in the rates of favorable outcomes, compared by χ2 met statistical significance (p = 0.014). The rate of complete aneurysm occlusion at 6 months was 42.5% in the FD group and 95% in surgical group (p < 0.0001). The rate of complete occlusion at 12 months was 65% in the FD group and 97.5% in surgical group. The difference between groups was still significant (p = 0.001). There were no significant differences between groups by occurrence of ischemic (p = 0.108) and hemorrhagic (p = 0.615) complications.

CONCLUSION

The study demonstrated superior clinical outcomes for endovascular flow diversion in comparison with bypass surgery in treatment of complex aneurysms. Though, both techniques grant similar percentage of major neurologic complications and comparable cure rate for cranial neuropathy. Nevertheless, flow diversion is associated with significantly lower early obliteration rate, thus possesses patient for risks of prolonged dual antiplatelet regimen and delayed rupture. Hence, it's important to stratify patient by the natural risk of aneurysm rupture prior to treatment selection.

Emergency Superficial Temporal Artery-Superior Cerebellar Artery Bypass for the Refractory Vertebrobasilar Insufficiency with Partial Mastoidectomy

BACKGROUND

Although it is well-known that vertebrobasilar insufficiency (VBI) because of atherothrombosis with bilateral vertebral artery (VA) occlusion is resistant to medical treatment from the acute to subacute stages, the most appropriate treatment for progressive infarction at these stages remains unclear. Here, we described a patient with VBI who underwent emergency superficial temporal artery-superior cerebellar artery (STA-SCA) bypass under partial mastoidectomy after confirming mismatch between diffusion-weighted imaging (DWI) findings and clinical symptoms. The patient showed a good outcome with this approach. To our knowledge, our surgical strategy has not been previously reported.

CASE DESCRIPTION

The patient was a 71-year-old woman with progressive infarction because of atherothrombosis with bilateral VA occlusions resistant to maximum medical treatment. Emergency STA-SCA bypass under partial mastoidectomy was performed after confirming DWI findings and symptom mismatch. A good outcome was archived, and no additional cerebral infarctions were noted.

CONCLUSIONS

Emergency bypass should be considered as a treatment option for VBI that is resistant to maximal medical treatment after confirming DWI findings and symptom mismatch. Our approach involving partial mastoidectomy provides a wide and shallow operative field for STA-SCA bypass, which allows accurate bypass with good outcomes.

[Revascularization experience and results in ischaemic cerebrovascular disease: Moyamoya disease and carotid occlusion]

INTRODUCTION

Cerebral revascularization techniques are an indispensable tool in the current armamentarium of vascular neurosurgeons. We present revascularization surgery experience and results in both moyamoya disease and occlusive cerebral ischaemia.

PATIENTS AND METHODS

Patients with ischaemic occlusive disease and moyamoya disease who underwent microsurgical revascularization between October 2014 and September 2017 were analysed.

RESULTS

In the study period, 23 patients with occlusive ischaemic disease underwent microsurgical revascularization. Three patients presented with serious postoperative complications (2 intraparenchymal haemorrhages in the immediate postoperative period and one thrombosis of the femoral artery). All patients, except one, achieved normalization of the cerebral hemodynamic reserve (CHR) in the SPECT study. Twenty patients had a good neurological result, with no ischaemic recurrence of the revascularized territory. Among patients with moyamoya, 20 had moyamoya disease and 5 had moyamoya syndrome with unilateral involvement. Five patients were treated at paediatric age. Haemorrhagic onset occurred in 2 patients. The CHR study showed hemodynamic compromise in all patients. Cerebral SPECT at one year showed resolution of the hemodynamic failure in all patients. There have been 4 postoperative complications (acute subdural hematoma, two subdural collections and one dehiscence of the surgical wound). No patient presented with neurological worsening at 6 and 12months of follow-up.

CONCLUSIONS

Cerebral revascularization through end-to-side anastomosis between the superficial temporal artery and a cortical branch of the middle cerebral artery is an indisputable technique in the treatment of moyamoya disease and possibly in a subgroup of patients with symptomatic occlusive ischaemic cerebrovascular disease.

Role of Indocyanine Green Videoangiography in Identification of Donor and Recipient Arteries in Cerebral Bypass Surgery

The identification and preparation of a very good quality donor artery is a crucial step in every superficial temporal artery to middle cerebral artery (STA-MCA) bypass.For flow-preservation bypass performed for trapping of complex MCA aneurysms, the key element is the correct target of the recipient artery. When a cortical recipient artery (M4 segment of the MCA) is selected, this vessel must be a terminal branch of the artery whose sacrifice is necessary for definitive aneurysmal treatment.In this chapter we report on two techniques for (1) intraoperative mapping and preparation of good quality STA branch as the donor artery for STA-MCA bypass (mostly in the case the frontal branch of the STA needs to be used) and (2) selective identification of the correct superficial (M4 cortical) "recipient" artery in flow-preservation STA-MCA bypass performed for managing complex MCA aneurysms.Both techniques are based on the use of microscope-integrated indocyanine green videoangiography (ICG-VA), an intraoperative tool allowing observation and real-time assessment of blood flow in large and small vessels, with distinct evaluation of arterial, capillary, and venous phases.The two techniques contribute, respectively, to (1) reduce the risk of erroneous identification or injury of the donor artery in STA-MCA bypass procedures and (2) eliminate the risk of erroneous revascularization of a non-involved arterial territory in flow-preservation bypass surgery for managing complex MCA aneurysms.

The V3 segment of the vertebral artery as a robust donor for intracranial-to-intracranial interpositional bypasses: technique and application in 5 patients

The V₃ segment of the vertebral artery (VA) has been studied in various clinical scenarios, such as in tumors of the craniovertebral junction and dissecting aneurysms. However, its use as a donor artery in cerebral revascularization procedures has not been extensively studied. In this report, the authors summarize their clinical experience in cerebral revascularization procedures using the V₃ segment as a donor. A brief anatomical description of the relevant techniques is also provided.

A Portable Training Model for Deep Bypass Surgery

INTRODUCTION

Deep bypass surgery remains a challenging operative procedure. For novice trainees, there is a high barrier to improving the microsurgical skills needed for this procedure because of the relatively low number of cases and the high cost of microsurgical instruments. Here, the authors introduce a training model that includes highly accessible devices and does not require a microscope.

MATERIALS AND METHODS

The surgical environment consisted of two 15.5-cm straight serrated forceps with a 1-mm tip width (Medicon, Tuttlingen, Germany), 9-cm curved iris scissors (Medicon), 4-0 black silk suture, gauze, and a 15 × 10.5 × 3.5-cm-sized box with a transparent cover. These materials are affordable even in low-income countries.

PROCEDURE

To understand and learn the hand positioning used in the deep surgical field, suturing practice was performed as follows: the forceps and a needle were placed in a slanted position, with hand position maintained at a 50° angle between the 2 forceps. This was also performed above the desk, without wrist support.

CONCLUSIONS

Our training system will be helpful, especially for deep bypass surgery, since training with similar muscle effort and fatigue can improve surgical skills. This system is economic, highly accessible, and available even for portable training.

Internal Maxillary Bypass for Complex Pediatric Aneurysms

BACKGROUND

Complex pediatric aneurysms (PAs) are an unusual clinicopathologic entity. Data regarding the use of a bypass procedure to treat complex PAs are limited.

METHODS

Internal maxillary artery-to-middle cerebral artery bypass with radial artery graft was used to isolate PAs. Bypass patency and aneurysm stability were evaluated using intraoperative Doppler ultrasound, indocyanine green videoangiography, and postoperative angiography. Modified Rankin Scale was used to assess neurologic function.

RESULTS

Over a 5-year period, 7 pediatric patients (≤18 years old) were included in our analysis. Mean age of patients was 14.4 years (range, 12-18 years), and mean size of PAs was 23.6 mm (range, 9-37 mm). All cases manifested with complex characteristics. Proximal artery occlusion was performed in 3 cases, complete excision following aneurysmal distal internal maxillary artery bypass was performed in 2 cases, and combined proximal artery occlusion and aneurysm excision was performed in the 2 remaining cases. Mean intraoperative blood flow was 61.6 mL/minute (range, 40.0-90.8 mL/minute). Graft patency rate was 100% during postoperative recovery and at the last follow-up examination (mean, 20 months; range, 7-45 months). All patients had excellent outcomes except for 1 patient who died of multiple-organ failure.

CONCLUSIONS

Internal maxillary artery bypass is an essential technique for treatment of selected cases of complex PAs.

Efficacy of superficial temporal artery-middle cerebral artery bypass in cerebrovascular steno-occlusive diseases: Hemodynamics assessed by perfusion computed tomography

OBJECTIVES

Our purpose of this study was to assess the cerebral hemodynamic improvement with perfusion computed tomography (CT), before and after superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery in patients with cerebrovascular steno-occlusive diseases including both moyamoya disease and nonmoyamoya steno-occlusions.

MATERIALS AND METHODS

Twenty-four STA-MCA bypasses were performed to 22 patients with symptomatic cerebrovascular steno-occlusive diseases, including both moyamoya disease and nonmoyamoya steno-occlusive diseases. Brain perfusion CT images were obtained before and after the bypass surgery. The relative parameters such as cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) derived from the perfusion CT were collected and analyzed to assess the efficacy of STA-MCA bypass.

RESULTS

The CBF increased, and MTT decreased after the bypass surgery in both moyamoya group and nonmoyamoya group. The increase of CBF in nonmoyamoya group and the decrease of MTT delay in moyamoya group, overall group were statistically significant (P < 0.05). No significant postoperative change in CBV was noted. During the postoperative follow-up period, none of the 22 patients experienced any repeated ischemic/hemorrhagic attacks nor any newly developed neurologic deficits.

CONCLUSION

The STA-MCA bypass is an effective surgical management for patients with cerebrovascular steno-occlusive diseases, such as moyamoya disease and internal carotid artery/MCA steno-occlusion. And perfusion CT can be used as an effective quantitative modality to assess the cerebral perfusion before and after the STA-MCA bypass surgery.

Indocyanine green videoangiography for the identification of superficial temporal artery branches in EC-IC bypass surgery

BACKGROUND

Superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass remains an essential tool for managing complex cerebrovascular conditions. A crucial surgical step is the identification and safe dissection of the bypass donor artery. If the frontal branch of the STA is used, a curvilinear fronto-temporal scalp flap generally allows for a clean dissection from the underside of the scalp flap. This dissection is sometimes tedious, since the frontal branch is not always easily visible and due to variability of its anatomy. With this article, we report on the feasibility and effectiveness of a simple indocyanine green videoangiography (ICG-VA)-assisted technique for the identification of the STA branches from the underside of a fronto-temporal scalp flap in bypass surgery.

METHODS

The technique is based on the analysis of the difference in timing of filling of scalp vessels illuminated via ICG-VA from the underside of a scalp flap. Three illustrative cases are reported.

RESULTS

ICG-VA permitted the correct identification and safe dissection of the donor vessels (STA branches) in all three patients. There were no complications due to the ICG-VA.

CONCLUSIONS

This technique allows reliable visualization of the STA and its branches at once before microsurgical dissection. The information provided by ICG-VA enables precise mapping and preparation of the STA. The simplicity and safety of this technique make it an effective tool for intraoperative identification of the STA and its branches.

The use of combined revascularization surgery for successful elimination of a middle cerebral artery aneurysm

OBJECTIVE

The study objective is to present a clinical case of successful surgical treatment of a complex middle cerebral artery (MCA) aneurysm using various types of bypasses.

MATERIAL AND METHODS

A 59-year-old female patient presented with nontraumatic intracranial hemorrhage caused by rupture of a complex right MCA aneurysm. The anatomical features of the MCA aneurysm were identified using computed tomography (CT) in angiographic and 3D modes. The surgical intervention included aneurysmectomy and an end-to-end reanastomosis between the M1 and M2 segments of the MCA followed by an extra-intracranial microvascular anastomosis (EICMA) between the frontal branch of the right superficial temporal artery (STA) and the cortical branch of the right MCA located on the frontal lobe surface.

RESULTS

The intraoperative blood flow via an intra-intracranial bypass (IC-IC bypass) was 30 mL/min, and the linear velocity of blood flow (LVBF) was 50 cm/s; the blood flow and LVBF via the STA-MCA bypass were 7-8 mL/min and 15 cm/s, respectively. CT angiography performed on the 1st postoperative day revealed the patency of the IC-IC and STA-MCA bypasses. The patient was discharged in satisfactory condition (Glasgow Outcome Scale -V) 1 month after surgery.

CONCLUSION

Revascularization surgery is the sought-after surgical technique for complex intracranial aneurysms that enables efficient exclusion of the aneurysm from blood flow and prevention of ischemic brain injuries in the carrying artery territory.

Indications and Outcomes of Prophylactic and Therapeutic Extracranial-to-intracranial Arterial Bypass for Cerebral Revascularization

Background:

Extracranial-to-intracranial (EC-IC) arterial bypass is a technically demanding procedure used to treat complex cerebral artery diseases. The indications, proper surgical techniques, and outcomes of this procedure have been under debate over the recent decades.

Methods:

Between January 2004 and December 2012, 28 patients, including patients with cerebral artery occlusion, intracranial aneurysm, cranial base tumor, and Moyamoya disease, underwent EC-IC bypass. Patients’ records were retrospectively reviewed for demography, indications, complications, high-flow versus low-flow bypass, patency rate of bypass, and neurological outcome. The patients were sorted into prophylactic (n = 16) and therapeutic (n = 12) groups based on the preoperative presentation of their neurological symptoms. Follow-up evaluation was performed at a mean of 32.7 ± 24.3 months.

Results:

The overall patency rate of bypass was 100%, the postoperative stroke rate was zero, and the surgical complication rate was 14.3%. There was no significant difference in the bypass patency rate between the 2 groups or between the high-flow and low-flow bypass patients. Patients who underwent prophylactic bypass had minimal surgical and total complications (P = 0.03 and P < 0.01, respectively) and a better neurological outcome. Surgical complications were more common in patients who underwent therapeutic bypass (25%).

Conclusions:

The collaboration of neurosurgeons and plastic surgeons in performing EC-IC bypass can result in excellent outcomes with a high bypass patency rate and few complications, particularly for prophylactic EC-IC bypass.

Bypass of the maxillary artery to proximal middle cerebral artery

OBJECTIVE

The objective of this work was to explore the feasibility of bypass between the maxillary artery (MA) and proximity of middle cerebral artery (MCA).

METHODS

Ten fixed and perfused adult cadaver heads were dissected bilaterally, 20 sides in total. The superficial temporal artery and its 2 branches were dissected, and outer diameters were measured. The MA and its branch were exposed as well as deep temporal artery; outer diameter of MA was measured. The lengths between the external carotid artery, internal carotid artery, maxillary artery, and proximal middle cerebral artery were measured. Ten healthy adults as targets (20 sides), inner diameter and blood flow dynamic parameters of the common carotid artery, external carotid artery, internal carotid artery, maxillary artery, superficial temporal artery, and its 2 branches were done with ultrasound examination.

RESULTS

The mean outer diameter of MA (2.60 ± 0.20 mm) was larger than that of the temporal artery trunk (1.70 ± 0.30 mm). The mean lengths of graft vessels between the internal carotid artery, external carotid artery, and the bifurcation section of MCA (171.00 ± 2.70 and 162.40 ± 2.60 mm) were longer than the mean lengths of graft vessels between MA and MCA bifurcation section (61.70 ± 1.50 mm). In adults, the mean blood flow of the second part of MA (62.70 ± 13.30 mL/min) was more than that of the 2 branches of the superficial temporal artery (15.90 ± 3.70 mL/min and 17.70 ± 4.10 ml/min).

CONCLUSION

Bypass between the maxillary artery and proximity of middle cerebral artery is feasible. It is a kind of effective high flow bypass with which the graft vessel is shorter and straighter than the bypass between internal carotid artery or external carotid artery and proximity of middle cerebral artery.

Occipital artery-to-posterior inferior cerebellar artery anastomosis with multiple-layer dissection of suboccipital muscles under a reverse C-shaped skin incision

Although occipital artery (OA)-to-posterior inferior cerebellar artery (PICA) anastomosis is the most familiar reconstruction for posterior cerebral circulation, the procedure is considered difficult because of the anatomical complex course of OA and the depth of the operative field at the anastomosis site. Therefore, we attempted a safe and reliable method for OA-to-PICA anastomosis under multiple-layer dissection of suboccipital muscles and a reverse C-shaped skin incision. We reviewed the clinical records of patients who underwent OA-to-PICA anastomosis in our institute, and report the outcome with special emphasis on graft patency and surgical complications. Nine patients are described. In one patient the bypass was accomplished at the cortical segment of the PICA and in all others at the caudal loop. The average time for de-clamping the PICA was 29 min and 29 s. Although the overall graft patency rate was 100%, one patient showed a new medulla infarction at the time of post-operatory three-dimensional computed tomography angiography. Besides a secure OA-to-PICA anastomosis, this technique allows safe harvest of the OA and the creation of a shallow and wide anastomosis field.