High-flow Extracranial-intracranial Bypass Research Articles

Distal Endovascular Occlusion for Incomplete Occlusion of Cavernous Carotid Aneurysms after High-flow Bypass and Cervical Internal Carotid Artery Ligation.

Internal carotid artery (ICA) ligation for placing a high-flow extracranial-intracranial (EC-IC) bypass is used in patients with aneurysms on the cavernous portion of the ICA. Recanalization and rupture after proximal ICA ligation can occur. We present four patients who underwent endovascular distal ICA occlusion and report our surgical technique and treatment results. We ligated the ICA to place an EC-IC bypass using a radial artery (RA) graft. Failure to obtain spontaneous occlusion in the distal region required endovascular treatment an average of 219 days later. A guide catheter was placed in the common carotid artery, a guide or distal access catheter was introduced in the RA graft from the external carotid artery, and a microcatheter was navigated into the cavernous aneurysm through the RA graft. Using detachable coils, endovascular ICA occlusion was from just distal to the aneurysmal neck to a site proximal to the origin of the ophthalmic artery. Aneurysmal occlusion was completed by endovascular occlusion of the distal ICA. Complications were RA graft stenosis and transient consciousness disturbance due to local subarachnoid hemorrhage. Outpatient follow-up for a mean of 109.5 months revealed no recurrences. Distal occlusion of the ICA through the implanted RA graft is simple and presents a low risk for cerebral infarction due to thrombus formation during the procedure. To treat cavernous carotid aneurysms that do not disappear after placing the EC-IC bypass after ICA ligation at the aneurysmal neck, we offer our procedure as a treatment option.

Post-operative Corona Radiata Infarct in a High-flow EC-IC Bypass: Report of Unusual Complication

AbstractLong insular artery (LIA) infarct can occur after insular glioma surgery. LIA infarct after extracranial-intracranial (EC-IC) bypass is very rare, and so far, it is not reported in EC-IC bypass. Here, we report a case of high-flow EC-IC bypass, where postoperatively, the patient developed isolated LIA infarct. A 65-year-old female presented with recurrent severe headache along with altered sensorium. Computed tomography (CT) scan and CT angiography (CTA) of the brain showed ruptured large left internal carotid artery (ICA) fusiform aneurysm. She underwent left-sided, high-flow EC-IC bypass involving upper trunk of left middle cerebral artery (MCA) and ICA ligation at neck at its origin. Postoperatively, the patient developed right sided hemiplegia. Postoperative MRI of the brain showed left-sided external capsular infarct, extending up to the corona radiata resulted from LIA infarct. By the end of 6 months after operation, she could walk with support but her left upper limb remained more severely affected and magnetic resonance angiogram (MRA) showed almost disappearance of aneurysm with functioning bypass.

External Carotid Artery-Related Adverse Events at Extra-Intra Cranial High Flow Bypass Surgery Using a Radial Artery Graft

Placing an extracranial-intracranial (EC-IC) high-flow bypass using a radial artery (RA) graft plus internal carotid artery (ICA) trapping or ligation is an option for treating patients expected to be at high risk for complications by direct surgical treatment of the ICA. We focused on the anastomosis between the external carotid artery (ECA) and the RA graft in the cervical region and present adverse events and salvage procedures. EC-IC high-flow bypass procedures using an RA graft were performed to treat 87 consecutive patients. The ECA diameter at the midpoint of the planned ECA-RA anastomosis and the non-branched length of the ECA were measured on preoperative angiograms. To study adverse events related to ECA-RA anastomoses, we reviewed the patients' surgical records and intraoperative videos. In 11 patients (12.6%) we encountered adverse events during anastomosis between the ECA and RA. The rate of ECA dissection was significantly higher in male patients (4 of 17; 23.5%) than female patients (3 of 70; 4.3%) (P= 0.012). Logistic regression analysis revealed that male sex, individuals with diabetes mellitus, and patients whose non-branching length of the ECA was short (16.1 ± 6.7 mm) were at high risk of ECA problems. We set the cutoff point at 17.5 mm (the area under the receiver operator characteristic curve was 0.72). Our findings indicate that patients, especially male patients, treated by EC-IC high-flow bypass using an RA graft are at increased risk for adverse events when the ECA length at the site of the planned anastomosis is shorter than 17.5 mm.

Successful Treatment of a Ruptured Blood Blister-like Aneurysm of the Internal Carotid Artery by Proximal Ligation with Extracranial-Intracranial High-flow Bypass: A Case Report

Successful Treatment of a Ruptured Blood Blister-like Aneurysm of the Internal Carotid Artery by Proximal Ligation with Extracranial-Intracranial High-flow Bypass: A Case Report

Extracranial-Intracranial High-Flow Bypass with Internal Carotid Artery Ligation at Neck for Giant Cavernous Internal Carotid Artery Dissecting Aneurysm in a Teen Girl with Postoperative Unusual Complication of Mono-ocular Blindness: A Case Report

AbstractExtracranial-intracranial (EC-IC) high-flow bypass with internal carotid artery (ICA) ligation at the neck is an important treatment option for giant cavernous ICA dissecting aneurysm. Such treatment may be associated with many complications. We report a case that developed postoperative mono-ocular blindness. So far to our knowledge such complication has not been reported in the literature. A 14-year-old girl presented with recent headache, eye ache, occasional double vision, and occasional right-sided visual impairment. Neurologic examination revealed no abnormality. Computed tomographic (CT) scan of the head showed a large, right parasellar, and mostly hyperdense space-occupying lesion. CT angiogram of the brain showed giant dissecting aneurysm of right-sided cavernous segment ICA. A right-sided external carotid artery–radial artery graft–middle cerebral artery (ECA-RAG-MCA [M2]) high-flow bypass was done with ligation of the right ICA in the neck. Postoperatively, the patient developed complete, mono-ocular, and permanent blindness on right side. Mono-ocular blindness is a serious complication from ophthalmic/central retinal artery thrombosis in high-flow EC-IC bypass with ICA ligation. Strategy is required to find and to set for its prevention.

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

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. 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. The mean age at treatment was 55years (range 34 to 67). The mean time of microsurgical procedure was 11h (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 10days after the microsurgical procedure and immediate postoperative epidural hematoma was noted in one other patient. 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.

Does Universal Bypass before Carotid Artery Occlusion Obviate the Need for Balloon Test Occlusion: Personal Experience with Extracranial-Intracranial Bypass in 23 Patients.

Aim:Carotid artery ligation carries a potential risk of ischemic complications even in patients with good collaterals and adequate cross-circulation. Preoperative assessment through balloon test occlusion (BTO) is technically challenging and not feasible in all patients. We analyze our experience with universal bypass without performing detailed cerebrovascular reserve (CVR) studies in 23 patients before carotid artery ligation.Patients and Methods:This was a retrospective analysis of the case records of 23 patients who underwent cervical carotid artery ligation for various indications since January 2009.Results:The study included 21 patients with cavernous carotid aneurysms, one patient with a large fusiform petrous carotid aneurysm, and one patient with recurrent glomus jugulare encasing the cervical internal carotid artery. The initial 12 patients underwent preoperative BTO with hypotensive challenge. All patients underwent a bypass procedure followed by carotid artery ligation irrespective of the BTO findings. Patients who successfully completed a BTO underwent a low-flow superficial temporal artery to middle cerebral artery bypass. A high-flow extracranial–intracranial bypass using a saphenous vein graft from external carotid artery to middle cerebral artery was done in all patients who either failed the BTO or did not undergo BTO. We had two operative mortalities and one poor outcome. All the other patients had a good recovery with a Glasgow outcome score of 5 at the last follow-up. Graft patency rates were 81.1% in both the low-flow and high-flow groups.Conclusion:Universal high-flow bypass is safe, effective, and should be preferred in all patients before carotid artery ligation. It obviates the need for detailed CVR assessment, especially in centers with limited resources.

Minimally Invasive Exposure of the Maxillary Artery at the Anteromedial Infratemporal Fossa.

The maxillary artery (MA) has been described as a reliable donor for extracranial-intracranial high-flow bypass. Existing techniques to harvest MA require brain retraction and drilling of the middle fossa (with or without a zygomatic osteotomy), carrying the potential risks of venous bleeding, injury to the branches of the maxillary or mandibular nerves, muscular transection, or temporomandibular junction disorders. To describe a novel technique to expose the MA without bony drilling and with minimal impact to surrounding structures. A conventional curvilinear incision was performed in 10 cadaveric specimens, prior to elevating the scalp to expose the zygomatic root and lateral orbital rim. The sphenozygomatic suture was followed to the anterolateral edge of the inferior orbital fissure (IOF) to locate and harvest the pterygoid segment of the MA. Topographic anatomy was assessed using surrounding landmarks and 3D Cartesian coordinates to define the surgical area. The number of visible MA branches and their lengths were recorded. The MA was successfully exposed in all specimens. This approach allowed 6 branches of MA to be exposed. The average length of exposure was 23.3±8.3 mm and the average surgical area was 2.8±0.9 cm2. The IOF was 11.5±4.2 mm from the MA. Our technique provides landmarks to identify the distal pterygoid segment of MA as a donor for extracranial-intracranial bypasses without the need for additional craniectomies. Clear anatomical landmarks, including the sphenozygomatic suture, anterolateral edge of IOF, infraorbital artery, and the pterygomaxillary fissure defined a trajectory to efficiently localize the MA with minimal risk to surrounding structures.

Extracranial-intracranial bypass and aneurysm trapping for the treatment of large and giant paraclinoid carotid aneurysms

Objective To explore the methods and effects of extracranial-intracranial (EC-IC) bypass and aneurysm trapping for the treatment of large and giant paraclinoid aneurysms. Methods The clinical data of 12 patients with paraclinoid aneurysms were analyzed retrospectively. Those patients were admitted to Department of Neurosurgery, the First Affiliated Hospital of Soochow University between April 2014 and February 2018. There were totally 12 aneurysms in 12 patients, including 8 giant and 4 large aneurysms. There were 1 case of postoperative bleeding of aneurysm embolization and 1 case of thrombotic aneurysms and 1 case of blood blister-like aneurysm. All cases underwent EC-IC high flow bypass and trapping of the aneurysms. The outcomes were evaluated based on the Glasgow Outcome Scale (GOS). Results Intraoperative fluorescein angiography and ultrasound suggested bridge vascular patency. The assessment at discharge indicated a GOS of 4-5 (good outcome) in 9 cases and GOS of 2-3 (severe disability) in 3 cases. There was no death. One was lost to follow-up. Eleven patients were followed up for 6-46 months post operation. The GOS of 4-5 (good outcome) was reported in 10 cases and 2 (severe disability) in 1 case. The bridge vascular patency was revealed in 10 cases. Conclusion The operation of EC-IC bypass combined with aneurysm trapping seems effective in the treatment of large and giant paraclinoid aneurysms. Key words: Intracranial aneurysm; Carotid artery, internal; Treatment outcome; Prognosis; Cerebral revascularization

Emergency high-flow bypass for the management of ruptured postirradiated internal carotid artery pseudoaneurysms in nasopharyngeal carcinoma patients

Abstract Rupture of a postirradiated internal carotid artery (ICA) pseudoaneurysm in patients with nasopharyngeal carcinoma (NPC) is a rare yet life-threatening emergency. In contrast to pseudoaneurysms found in patients with other head and neck malignancies, those identified in NPC patients have a propensity to occur in the petrous segment of the ICA, which pose a serious challenge to clinical physicians. Over the past few decades, endovascular treatment with covered stents has widely been adopted as the treatment of choice for patients at risk of brain ischemia after occluding the parent vessel of the pseudoaneurysm. Although recent series have demonstrated that immediate hemostasis can be achieved in most of the patients undergoing covered stent placement, a high incidence of delayed complications has been reported, including delayed cerebral ischemia, in-stent thrombosis, and septic thromboembolism. We present two NPC patients with a postirradiated pseudoaneurysm involving the petrous segment of the internal carotid artery. As direct parent vessel occlusion was infeasible, we established an emergency high-flow extracranial-intracranial (EC-IC) bypass followed by endovascular parent vessel occlusion. Both of the patients were followed-up for more than 24 months without neurological deficit or rebleeding. We suggest that EC-IC bypass with parent vessel occlusion should be considered as a practical and durable treatment option for patients with postirradiated ICA pseudoaneurysms who cannot tolerate direct carotid occlusion.

The use of high-flow extracranial-intracranial artery bypass in pathology of the cerebral and brachiocephalic arteries: technical features and surgical outcomes

Poor outcomes of surgical treatment for complex cerebral aneurysms due to the development of cerebral ischemia were the cause to use cerebral revascularization surgery for this pathology. the study objective was to master a high-flow extracranial-intracranial (EC-IC) artery bypass technique and evaluate its application in surgical treatment of complex and giant cerebral aneurysms as well as complex lesions of the brachiocephalic arteries. Fifty two patients underwent high-flow IC-EC bypass surgery; of these, 34 patients had complex cerebral aneurysms, and 18 patients had complex stenotic occlusive lesions of the brachiocephalic arteries. After bypass placement, the patients with aneurysms underwent different variants of aneurysm exclusion (trapping or proximal clipping/ligation of the parent artery). All patients underwent follow-up studies of the bypass function and clinical condition in the early postoperative period and 6 and 12 months after surgery. High-flow IC-EC bypass surgery is routinely used in clinical practice of the Novosibirsk Federal Center of Neurosurgery. Fifty one out of the 52 patients were followed-up in a range of 4 to 56 months. According to the direct or CT angiography data, bypasses functioned in 51 (98.1%) patients in the early and long-term postoperative periods. The clinical efficacy (no ischemic changes and improved cerebral perfusion) of high-flow IC-EC bypasses was demonstrated in 31 (91.2%) of 34 patients with aneurysms and in 17 (94.4%) of 18 patients with complex lesions of the brachiocephalic arteries. The total number of surgical complications was 8 (15.4%) cases: 7 complications occurred in patients with aneurysms, and 1 complication developed in a patient with bilateral ICA occlusion. Of these, ischemic complications developed in 4 (7.7%) cases, hemorrhagic complications occurred in 2 (3.8%) cases, and cranial nerve complications were found in 2 (3.8%) cases. One (1.9%) female patient with a giant aneurysm died from hemispheric stroke due to insufficient blood flow through the bypass. Implementation of a large number of surgeries enabled improvement of the technique and clarification of the prerequisites for preoperative examination, intraoperative control, and postoperative management of patients. A low mortalits rate suggests this technique for use in clinical practice. The surgery is indicated for the treatment of giant aneurysms of the petrous, cavernous, and clinoid segments of the ICA. In the case of giant supraclinoid aneurysms, the surgery may be combined with removal of thrombotic masses from the aneurysm sac for rapid decompression of the cranial nerves. Application of this surgery for treatment of giant aneurysms of the trunk and bifurcation of the basilar artery is promising but requires further investigation. The surgery is also recommended for improving cerebral perfusion in the setting of complex stenotic occlusive lesions of the BCA: prolonged BCA stenoses, tandem ICA stenoses located in both the extracranial and intracranial segments, nonspecific vasculitis and arteriitis, subcranial aneurysms, kinking etc.

High-flow extracranial-intracranial bypass for complex intracranial aneurysms

Objective To summarize the efficacy and experiences of high-flow extracranial-intracranial bypass for complex intracranial aneurysms. Methods From August 2010 to August 2015, the clinical data of 55 patients with intracranial aneurysm treated with high-flow extracranial-intracranial bypasses at the Department of Neurosurgery, Xiangya Hospital, Central South University were analyzed retrospectively. Fifteen patients conducted balloon occlusion test(BOT)before procedure, and 11 of them could not tolerate it. The grafts were the radial artery, the calf or thigh saphenous vein segment; the feeding arteries were common carotid(external))artery, maxillary artery, and superficial temporal artery trunk; the middle cerebral arteries were the blood reception arteries in anterior circulation; the posterior cerebral arteries were the blood reception arteries in posterior circulation. Results There were no death in this group of patients. The grafts of all patients were patent at day 1 after procedure. One patient had hemiplegia immediately after surgery. CT scan revealed that a small infarct was in the basal ganglia region. The muscle strength reached grade Ⅲ-Ⅳ at day 8 after surgery. The grafts(saphenous vein of the calf segment)of 2 patients were occluded at day 3 and day 4 without symptoms. The graft(radial artery)of 1 patient was occluded at day 25 after procedure. Forty-three patients were followed up for 6 months to 52 months. The grafts(saphenous veins of the calf segment)of 2 patients were occluded at 6 months after procedure without any symptoms. In 5 patients with the graft occlusion did not conduct BOT. Conclusions High-flow extracranial-intracranial bypass for the treatment of complex intracranial aneurysms is effective. All the selected feeding vessels meet the requirements of blood supply. Graft occlusion may occur early or late after surgery. As grafts, both the saphenous vein of the calf segment and radial artery are more prone to occlusion. If they are well compensated, they may not have any clinical symptoms. Key words: Cerebral revascularization; Intracranial aneurysm; High flow

High flowバイパス 20年後のグラフト血管に発生した破裂部分血栓化巨大動脈瘤の治療例

Cerebral revascularization with high-flow extracranial-intracranial (EC-IC) bypass is generally indicated in patients with complex intracranial aneurysms. This is the first reported case of aneurysm formation followed by rupture occurring on the graft itself, which was constructed to treat a patient with a giant internal carotid artery (ICA) aneurysm. A-78-year-old woman who had undergone right EC-IC bypass using a saphenous vein graft and ligation of the right cervical ICA to treat an unruptured right ICA giant aneurysm 20 years earlier presented with a subarachnoid hemorrhage (SAH). Computed tomography (CT) on admission revealed a ring-like mass in the right temporal lobe with an SAH. Angiography showed a fusiform aneurysmal formation on the graft just before the anastomotic site. We initially performed detachable coil embolization of the aneurysm with a stent in the acute stage. Next, endovascular trapping of the parent artery (saphenous vein graft) and removal of intraaneurysmal thrombus were performed, after we created a new high-flow EC-IC bypass using a radial artery. We report this case along with a review of the literature.

Emergency Extracranial-Intracranial Bypass during Surgery for Anterior Clinoid Process Hemangiopericytoma with ICA Invasion—Case Report

Hemangiopericytoma (HPC) is a rare tumor, accounting for less than 1% of intracranial tumors. Though it’s notoriously difficult to distinguish HPC from meningioma in pre-op images, HPC presents bone and vascular invasion, high local recurrence and distal metastasis clinically, as a surgically challenging malignancy. High-flow extracranial-intracranial (EC-IC) bypass is a skill demanding surgery and is usually performed as a wellprepared elective surgery. However, emergency EC-IC bypass is indicated for unplanned major artery loss during surgery and sometimes as the final rescue for the patient. We present a case of 46 year-old man, who was diagnosed of a left anterior clinoid process (ACP) tumor with presentation of gradually visual loss. As the dura tail sign and MRI signal, we performed left pterional approach tumor excision for the impression of ACP meningioma. However, due to the vascular invasion of tumor, left ICA perforation was noted intraoperatively and finally the bleeding was controlled with ICA clipping. Emergency EC-IC bypass from common carotid artery to middle cerebral artery was performed. The patient recovered to oriented consciousness, independent ambulation but mild aphasia in our outpatient department follow-up.

Urgent cerebral revascularization bypass surgery for iatrogenic skull base internal carotid artery injury.

When feasible, the management of iatrogenic internal carotid artery (ICA) injury during skull base surgery is mainly endovascular. To propose a cerebral revascularization procedure as a rescue option when endovascular treatment is not feasible. We retrospectively reviewed all extracranial-intracranial (EC-IC) bypass procedures performed between July 2007 and January 2014. From 235 procedures, we identified 8 consecutive patients with iatrogenic ICA injury managed with an EC-IC bypass. Injury to the ICA occurred during an endoscopic transsphenoidal surgery (n=3), endoscopic transfacial-transmaxillary surgery (n=1), myringotomy (n=1), cavernous sinus meningioma resection (n=1), posterior communicating artery aneurysm clipping (n=1), and cavernous ICA aneurysm coiling (n=1). Endovascular management was considered first-line treatment but was not successful. All patients received a high-flow EC-IC bypass. At a mean clinical/radiographic follow-up of 19 months (range, 3-36 months), all patients had a modified Rankin Scale score of 0 or 1. All bypasses remained patent. Iatrogenic injury of the skull base ICA is uncommon but can lead to lethal consequences. Many injuries can be treated with endovascular techniques. However, certain cases may still require a cerebral revascularization procedure.

Monitoring Flow in Extracranial-Intracranial Bypass Grafts Using Duplex Ultrasonography

High-flow extracranial-intracranial (EC-IC) bypass is performed by using radial artery graphs (RAGs) or saphenous vein grafts (SVGs) for various pathologies such as aneurysms, ischemia, and skull-base tumors. Quantifying the acceptable amount of blood flow to maintain proper cerebral perfusion has not been well established, nor have the variables that influence flow been determined. To identify the normative range of blood flow through extracranial-intracranial RAGs and SVGs as measured by duplex ultrasonography. Multiple variables were evaluated to better understand their influence of graft flow. All EC-IC grafts performed at Harborview Medical Center from 2005 to 2012 were retrospectively reviewed for this cohort study. Daily extracranial graft duplex ultrasonography with flow volumes and transcranial graft Doppler were examined, as were short- and long-term outcomes. Both ischemic and hyperemic events were evaluated in further detail. Eighty monitorable high-flow EC-IC bypasses were performed over the 8-year period. Sixty-five bypasses were performed by using RAGs and 15 were performed with SVGs. The average flow was 133 mL/min for RAGs and 160 mL/min for SVGs (P = .25). For both RAG and SVG groups, the donor and recipient vessel selected significantly impacted flow. For the RAG group only, preoperative graft diameter, postoperative hematocrit, and postoperative date significantly influenced flow. A 1-week average of >200 mL/min was 100% sensitive to cerebral hyperemia syndrome. This study establishes the normative range of duplex ultrasonographic flow after high-flow EC-IC bypass, as well the usefulness and practicality of such monitoring as a surrogate to flow in the postoperative period.

内頚動脈前壁動脈瘤破裂に対する高灌流EC-IC bypass/動脈瘤トラッピング術後急性期の脳循環動態とMR所見の検討

Background: Extracranial-intracranial (EC-IC) bypass is a powerful tool for treating complex cerebral aneurysm. Ruptured aneurysms at the non-branching site of the internal carotid artery (ICA), the so-called blister-like aneurysm, have been treated with high flow EC-IC bypass and aneurysmal trapping, but postoperative cerebral hemodynamics following flow conversion have remained unclear. Methods: The present study investigated six cases with ruptured blister-like ICA aneurysm, who were managed by high flow EC-IC (ECA-M2 or CCA-M2) bypass using interposed saphenous vein graft followed by microsurgical aneurysmal trapping. Postoperative cerebral blood flow (CBF) was evaluated by N-isopropyl-p-[123I]iodoamphetamine single-photon emission computed tomography (SPECT) in the acute stage. Routine magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) were also performed in the acute stage. Results: No patient suffered from intra-operative aneurysmal rupture, and no patient manifested procedure-related ischemic complications. Postoperative SPECT in the acute stage (1‐3 days after surgery) demonstrated a mild decrease in CBF in the operated hemisphere. Postoperative MRA demonstrated apparently patent EC-IC bypass in all cases. One patient manifested a delayed vasospasm and required a diagnostic angiogram and an intra-arterial infusion of fasudil hydrochloride. The clinical outcome was as follows: GR (good recovery) in four patients, and MD (moderately disabled) in two patients. Conclusion: High flow EC-IC bypass followed by aneurysmal trapping (ICA trapping) was found to be a safe and effective treatment for ruptured blister-like ICA aneurysm. We recommend postoperative SPECT and MRI/MRA in the acute stage to monitor cerebral hemodynamics after flow conversion.

Simulation of a High-Flow Extracranial-Intracranial Bypass Using a Radial Artery Graft in a Novel Fresh Tissue Model

Microsurgical vascular anastomosis techniques are technically challenging and used in only a narrow spectrum of neurosurgical procedures. Opportunities for instruction and application have become increasingly rare during standard neurosurgery residencies. To create a neurovascular simulation model that more closely approximates the clinical environment. This article describes a novel surgical model using vascular pressurization in a fresh cadaver to simulate an extracranial-to-intracranial bypass. Fresh cadavers were obtained according to the standard operating procedures of the University of Southern California Fresh Tissue Dissection Laboratory. The femoral vessels were cannulated and the entire cadaver pressurized. A high-flow bypass from the common carotid artery to the middle cerebral artery was performed using a radial artery graft. This system has several advantages for neurosurgical simulation. The fresh tissue reproduces intraoperative haptics and anatomy. Extracranial-to-intracranial bypass is a physically demanding procedure and can become fatiguing and frustrating for beginners. This model more closely simulates clinical operative time and conditions. The surgeon is able to rehearse the steps and progression of the operation as opposed to simply focusing on the anastomosis. Surgeon positioning and microscope placement are often difficult for novices. By simulating the operating room conditions, these steps can be practiced, providing experience that can be directly translated to the clinical arena. Despite the decrease in frequency, indications for bypass procedures still exist in neurosurgery. The fresh tissue pressurization model offers significant benefits when training neurosurgeons to perform these technically demanding procedures.

Basic Aspects of High-Flow Extracranial-Intracranial Bypass: Part II

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Magnetic Resonance Imaging Flow Quantification of Non-Occlusive Excimer Laser-Assisted EC-IC High-Flow Bypass in the Treatment of Complex Intracranial Aneurysms

The patency of a bypass plays an important role in the postoperative recovery of patients especially when dealing with complicated intracranial aneurysms. In this study two-dimensional phase contrast magnetic resonance angiography (PC-MRA) was used to measure cerebral blood flow in 23 patients before extracranial-intracranial high-flow bypass surgery using the excimer laser-assisted non-occlusive anastomosis (ELANA) technique and in 15 patients following surgery. The results showed that PC-MRA is a suitable technique for assessing bypass patency and that with the ELANA technique the bypass has the capability of compensating the blood flow of an occluded internal carotid artery (ACI) in cases of complex aneurysms.