Extracranial-to-intracranial Research Articles

Short Segment Internal Maxillary Artery to Middle Cerebral Artery Bypass: A Novel Technique for Extracranial-to-Intracranial Bypass

Traditional high-flow extracranial-to-intracranial (EC-IC) bypass procedures require a cervical incision and a long (20-25 cm) radial artery or saphenous vein graft. This technical note describes a less invasive, EC-IC bypass technique using a short-segment (8-10 cm) of the radial artery to anastomose the internal maxillary artery (IMAX) to the middle cerebral artery. Anatomic dissections were performed on 6 cadaveric specimens to assess the location of the IMAX artery using an extradural middle fossa approach. Subsequently, the procedure was implemented in a patient with a giant fusiform internal carotid artery aneurysm. A straight line was drawn anteriorly from the V2/V3 apex along the inferior edge of V2. The IMAX was found 8.6 mm on average anteriorly from the lateral edge of the foramen rotundum. We drilled to a depth of 4.2 mm on average to find the medial extent of the artery and then lateral and deep drilling exposed an average of 7.8 mm of graft. The IMAX was consistently found running just anterior and parallel to a line between the foramens rotundum and ovale. In the clinical case presented, both intraoperative indocyanine green and postoperative conventional angiography revealed a patent graft. The patient did well clinically without any new deficits. The advantages of this new technique include the avoidance of a long cervical incision and potentially higher patency rates secondary to shorter graft length than currently practiced.

Surgery Management of Giant Serpentine Aneurysm: A Case Report and Literature Review

We report a case of giant serpentine aneurysm (GSA) of the right middle cerebral artery (MCA) that successfully treated by an extracranial to intracranial (ECA/ICA) bypass with a graft from the superficial temporal artery of the external carotid artery to a temporal lobe branch of the middle cerebral artery. The patient was a 36 years old man who presented to our hospital with an acute headache. CT and MR examinations revealed a large serpentine aneurysm arising from right MCA. Angiography demonstrated a GSA. After revascularization, the patient obtained a very good outcome. J Med Cases. 2011;2(6):260-261 doi: https://doi.org/10.4021/jmc288e

Short Segment Internal Maxillary Artery to Middle Cerebral Artery Bypass: A Novel Technique for Extracranial-to-Intracranial Bypass

Background Traditional high-flow extracranial-to-intracranial (EC-IC) bypass procedures require a cervical incision and a long (20-25 cm) radial artery or saphenous vein graft. This technical note describes a less invasive, EC-IC bypass technique using a short-segment (8-10 cm) of the radial artery to anastomose the internal maxillary artery (IMAX) to the middle cerebral artery. Clinical presentation Anatomic dissections were performed on 6 cadaveric specimens to assess the location of the IMAX artery using an extradural middle fossa approach. Subsequently, the procedure was implemented in a patient with a giant fusiform internal carotid artery aneurysm. Technique A straight line was drawn anteriorly from the V2/V3 apex along the inferior edge of V2. The IMAX was found 8.6 mm on average anteriorly from the lateral edge of the foramen rotundum. We drilled to a depth of 4.2 mm on average to find the medial extent of the artery and then lateral and deep drilling exposed an average of 7.8 mm of graft. The IMAX was consistently found running just anterior and parallel to a line between the foramens rotundum and ovale. In the clinical case presented, both intraoperative indocyanine green and postoperative conventional angiography revealed a patent graft. The patient did well clinically without any new deficits. Conclusion The advantages of this new technique include the avoidance of a long cervical incision and potentially higher patency rates secondary to shorter graft length than currently practiced.

Localization of the Internal Maxillary Artery for EC-IC Bypass through the Middle Cranial Fossa: A Cadaveric Study

Background: The internal maxillary artery (IMAX) is a promising arterial pedicle to function as a donor vessel for extracranial-to-intracranial (EC-IC) bypass procedures. The access to the IMAX through the anterior portion of the middle fossa floor allows a much shorter interposition graft to be used to create a bypass to the ipsilateral MCA and prevents a second incision in the neck. This procedure has already been done successfully in the operating room; however, one of the challenges to solidify this technique has been the need to establish a reliable method to localize the IMAX through the middle fossa floor based on skull base landmarks. The purpose of this cadaveric study is to establish such relationships between the position of the IMAX as approached through the middle fossa floor and identifiable bony landmarks in the skull base.

Extracranial-intracranial arterial bypass surgery for occlusive carotid artery disease.

The EC/IC Bypass Study Group found no benefit of extracranial to intracranial (EC/IC) bypass surgery over medical therapy in patients with symptomatic carotid artery occlusion (sCAO). However, the study was criticised for many reasons and the real effect of this treatment is still not known conclusively. To determine whether bypass surgery plus medical care is superior to medical care alone in patients with sCAO. We searched the Cochrane Stroke Group Trials Register (last searched June 2009). In addition, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2006), MEDLINE (1966 to June 2009) and EMBASE (1980 to June 2009). We also searched ongoing trials and research registers, checked reference lists of relevant articles, and contacted colleagues, trial authors and researchers. Randomised controlled trials (RCT) and non-random studies of EC/IC bypass surgery plus best medical treatment compared with best medical treatment alone to prevent subsequent stroke, improve cerebral haemodynamics and reduce dependency after stroke. Two review authors independently selected studies for inclusion, and extracted data items on the number of outcome events onto a data extraction form. We only analysed secondary outcomes if the study provided information on at least one primary outcome. We also used intention-to-treat analysis where possible. We included 21 trials, including two RCTs, involving 2591 patients. For all endpoints, no benefit of EC/IC bypass surgery was shown either in the RCTs (any death: odds ratio (OR) 0.81, 95% confidence interval (CI) 0.62 to 1.05, P = 0.11; stroke: OR 0.99, 95% CI 0.79 to 1.23, P = 0.91; death and dependency: OR 0.94, 95% CI 0.74 to 1.21, P = 0.64), or in the non-RCTs (any death: OR 1.00, 95% CI 0.62 to 1.62, P = 0.99; stroke: OR 0.80, 95% CI 0.54 to 1.18, P = 0.25; death and dependency: OR 0.80, 95% CI 0.50 to 1.29, P = 0.37). EC/IC bypass surgery in patients with sCAO disease was neither superior nor inferior to medical care alone. However, most studies included patients irrespective of their cerebral haemodynamics. Participation in an ongoing RCT, which is restricted to patients with impaired haemodynamics, is recommended as these patients might benefit from bypass surgery.

Predictors of patency of excimer laser–assisted nonocclusive extracranial-to-intracranial bypasses

Excimer laser-assisted nonocclusive anastomosis (ELANA) is a technique that can be used for extracranial-to-intracranial (EC-IC) bypasses, without the necessity of temporary occlusion of the donor or recipient artery. Information on predictors of patency of EC-IC bypasses in general and the ELANA bypass in particular is sparse. The authors studied 159 ELANA EC-IC bypasses to find predictors of patency. From a prospective database of patients who underwent EC-IC bypass surgery, 143 consecutive patients who underwent a total of 159 ELANA bypasses were studied. The associations of patient characteristics, surgical aspects, and technical aspects specific to the ELANA technique with intraoperative and postoperative bypass patency were studied using logistic regression analysis. At the end of the operation, 146 (92%) of the 159 bypasses were patent. A first attempt to create a bypass was almost 8 times more likely (OR 7.6, 95% CI 2.1-27.5; p = 0.02) to result in a patent bypass than a second attempt. Administration of a small amount of heparin during the operation was also associated with bypass patency (OR 5.2, 95% CI 1.1-24.9; p = 0.04). One hundred twenty-three (77%) of the 159 bypasses were functional at patency assessments during the 1st month after the operation. Older age (OR 1.043 for every year of increase in age, 95% CI 1.010-1.076; p = 0.01), male sex (OR 2.9, 95% CI 1.3-6.5; p = 0.01), and high intraoperative bypass flow (OR 1.017 for every milliliter per minute increase in flow, 95% CI 1.004-1.030; p = 0.01) were associated with postoperative bypass patency. Attempts to create a second EC-IC ELANA bypass after the first one are more likely to fail, whereas administration of heparin to the patient during the procedure increases the intraoperative bypass patency rate. Postoperative patency results are better in male and in older patients. Intraoperative bypass flow measurements are essential because high bypass flow is an important determinant of postoperative patency.

EC-IC bypass: The failure of a clinical trial? Applicability to PFO closure trials

Extracranial-to-intracranial (EC-IC) bypass surgery was used to prevent stroke in patients with carotid occlusion and inadequate collateral flow. Because of inappropriate proliferation of EC-IC bypass, a randomized clinical trial was carried out. The failure of the trial may have been related to inappropriate patient selection and all eligible patients not being randomized. Subsequent study has identified criteria for patient selection and new trials are underway. The present patent foramen ovale closure trials share many of the same difficulties, including overuse of the procedure and interventionalists reluctant to randomize patients. If these trials are not properly done we will be in the same situation in 20 years that the EC-IC trialists are facing today. Improvements in patient selection criteria, randomization of all eligible patients, and better statistical parameters will increase the likelihood of future trials getting the correct answer the first time. The importance of carefully done observational trials should not be overlooked.

Successful Staged Obliteration of Three Unruptured Cerebral Aneurysms by Clipping, Coiling, and Proximal Occlusion: Report of a Case

Endovascular techniques offer a mode of therapy alternative or adjuvant to surgery in treatment of multiple or inoperable cerebral aneurysms. Proximal arterial occlusion, with or without extracranial-to-intracranial (EC-IC) bypass, is frequently performed for inoperable cerebral aneurysms. The authors report hereby a 70-yearold woman presenting with the left cavernous sinus syndrome because of a giant inoperable internal carotid aneurysm. In addition, two other aneurysms were identified. The patient underwent staged obliteration of the three aneurysms by clipping, Guglielmi detachable coils (GDCs) embolization, and proximal internal carotid artery occlusion with golden valve balloons (GVBs). At 5-month follow-up, the cerebral angiogram showed that the left ICA aneurysm was completely obliterated, the right ICA aneurysm was totally occluded by GDCs, and the left MCA aneurysm was successfully clipped. In addition, the collateral circulation of the left hemisphere had been well reestablished. Symptoms and signs of the left cavernous sinus syndrome subsided about three months after the treatment. Triple aneurysms can be managed successfully with a combination of different therapies.

Extracranial-to-Intracranial Bypass Using Radial Artery Grafting for Complex Skull Base Tumors: Technical Note

The management of complex skull base tumors that incorporate large intracranial vessels poses challenging questions. Patients who fail initial surgical resection and adjunctive therapies (i.e., radiosurgery) who present with tumor regrowth may be candidates for parent vessel occlusion and total tumor resection in combination with extracranial-to-intracranial (EC-IC) bypass to augment the sacrificed vessel territory. In this technical report, we delineate the surgical technique of performing an EC-IC bypass using a radial artery graft. Our protocol of simultaneous cranial, neck, and forearm dissections by the surgical team to perform this procedure is described in detail.

CAN WE IDENTIFY PATIENTS WITH CAROTID OCCLUSION WHO WOULD BENEFIT FROM EC/IC BYPASS? REVIEW

Occlusion of the internal carotid artery (CAO) is associated with a high mortality rate and frequent disability in survivors. Even in patients with good clinical recovery there is a high risk of recurrent stroke, mainly in those with impaired cerebral vasomotor reactivity (CVR). Current evidence based therapeutic options for patients with symptomatic CAO include antithrombotic medication and control of vascular risk factors. For stenosis of the contralateral internal or ipsilateral external carotid artery, endarterectomy or percutaneous transluminal angioplasty may be considered. Ongoing symptoms may cease after tapering antihypertensive medications. Extracranial to intracranial (EC/IC) arterial bypass surgery has been used since 1967 in patients with CAO. However, the international randomized EC/IC Bypass Study (1985) failed to confirm the effectiveness of EC/IC bypass for preventing cerebral ischemia in patients with symptomatic CAO when compared to those assigned to the best medical care. Nevertheless, the conclusion of the EC/IC Bypass Study has several objections and downfalls. Since then, there has been a revival of interest in cerebral revascularization procedures owing to the substantial progression of surgical techniques and the use of more advanced diagnostic methods. Thus, it has recently been reported that EC/IC bypass surgery can be useful in preventing stroke in patients with hemodynamic compromise. The main problem is to identify the small subgroup of surgical candidates. Presently, single photon emission computed tomography (SPECT), positron emission tomography (PET), transcranial Doppler sonography (TCD), computed tomography (CT) with administration of (133)Xe, perfusion CT, near infrared spectroscopy (NIRS), and functional magnetic resonance imaging (fMRI) are being used for this purpose.

Cerebral revascularization.

During the last 10 years, there has been a revival of interest in cerebral revascularization procedures. Not only have significant progressions in surgical techniques been published, the use of more advanced diagnostic methods has led to a widening of the indications for cerebral bypass surgery. The purpose of this review is to outline the current techniques for extracranial-to-intracranial (EC/IC) and intracranial-to-intracranial (IC/IC) bypass surgery, as well as to identify the current indications for revascularization procedures based on the available literature. The excimer laser-assisted non-occlusive anastomosis (ELANA) technique is described in more detail because we think that this technique almost completely eliminates the risk of cerebral ischemia due to the temporary vessel occlusion which is currently used in conventional anastomosis techniques.

Reduced stroke risk in patients with compromised cerebral blood flow reactivity treated with superficial temporal artery to distal middle cerebral artery bypass surgery

Extracranial-to-intracranial (EC-IC) bypass surgery for the prevention of stroke in patients with symptomatic carotid artery occlusion has nearly ended after a randomized trial showed no benefit of the procedure. Although an EC-IC bypass might benefit patients with compromised cerebrovascular hemodynamics, the randomized trial did not differentiate patients with hemodynamic from embolic etiologies. However, subsequent investigators have identified a subgroup of patients at increased stroke risk from hemodynamic compromise. We examined the subsequent stroke rate of 42 patients with symptomatic carotid occlusion at high risk for stroke identified as having a baseline cerebral blood flow (CBF)<45 mL/100 g/min and a >5% CBF reduction in one vascular territory after a vasodilatory challenge from 1 g of intravenous acetazolamide on stable xenon-computed tomography (CT) CBF imaging. Thirty patients (group 1) treated medically were a subgroup with carotid occlusion from our long-term natural history study. During a median follow-up of 12 months, 9 patients (30%) had a new stroke within a median of 5 months. Twelve patients (group 2) had recurrent, disabling cerebral ischemic symptoms, with 8 progressing to mild fixed neurological deficits from deep white matter infarction identified on CT. All were treated with superficial temporal artery to distal middle cerebral artery (STA-MCA) bypass with restoration of cerebrovascular reserve postoperatively; none had a stroke during the 18-month minimum follow-up (P=.041). Perioperative morbidity included subendocardial infarction in one and a small, asymptomatic left frontal hemorrhage in another patient. Early postoperative and delayed xenon/CT CBF studies obtained a median of 5 months postoperatively showed maintenance of cerebrovascular reserve. STA-MCA bypass surgery can restore cerebrovascular reserve in high-risk patients with symptomatic internal carotid artery occlusion. This was achieved with minimal perioperative complications, resulting in a subsequent reduction of stroke frequency. We suggest that the efficacy of STA-MCA bypass surgery for symptomatic carotid occlusion be re-examined prospectively using hemodynamic selection criteria.

Assessment of Risk of Carotid Occlusion with Balloon Matas Testing and Dynamic Computed Tomography

Temporary occlusion of the internal carotid artery with a balloon catheter (balloon Matas test) and simultaneous dynamic computed tomographic scanning (DCT) were performed in four patients with intracranial aneurysms in order to determine their tolerance for permanent carotid occlusion. Five DCT parameters were evaluated: appearance time (AT), peak time (PT), peak height fitting (PH), first effective moment (MT1E), and transit time (TT). The results of DCT and balloon Matas testing disclosed three patterns. Type 1 consisted of two patients with no neurological dificit during the balloon Matas test, while DCT showed a parallel shift of the time-density curve in the region of the middle cerebral artery on the occluded side relative to that of the contralateral side. Whereas PH, MT1E, and TT were the same on both sides, AT and PT were delayed on the occluded side. The DCT findings indicated that cerebral blood flow (CBF) was equally preserved in the two hemispheres during carotid occlusion. Thus, abrupt internal carotid arterial occlusion appears to be a safe procedure in Type 1 patients. In Type 2, the balloon Matas test showed no neurological deficit, but the time-density curve revealed deficits in all five DCT parameters in the area of the middle cerebral artery on the occluded side. These findings were confirmed by the functional images. A decrease in CBF on the occluded side was also suggested. Therefore, in Type 2 cases, extracranial-to-intracranial (EC-IC) bypass surgery should be performed to prevent ischemic insult. In Type 3, such neurological signs as disturbance of consciousness, aphasia, and right hemiparesis appeared just after the start of the balloon Matas test. The DCT findings were almost the same as those of Type 2 in the region of the middle and anterior cerebral arteries on the occluded side. Occlusion of the internal carotid artery is therefore contraindicated in Type 3 patients unless an EC-IC bypass procedure that can rapidly provide a large supply of blood (e.g., vein graft bypass) is performed. The authors conclude that the balloon Matas/DCT method offers a reliable means of predicting the risk of carotid ligation.

Cerebral vasospasm: theoretical causes, medical management, and nursing implications.

Cerebral vasospasm is a potentially life-threatening complication following subarachnoid hemorrhage (SAH) from a ruptured cerebral artery aneurysm. Traditionally, vasospasm has been treated with a variety of medical interventions. However, surgical intervention with an extracranial to intracranial (EC/IC) bypass graft has yielded promising results in a limited group of patients. This article discusses the theoretical causes of cerebral vasospasm, its clinical presentation, diagnosis, and treatment modalities. Nursing interventions for the patient experiencing cerebral vasospasm are also presented.