Late patency of long saphenous vein bypass grafts to the anterior and posterior cerebral circulation

Proximal Clipping and Distal High-Flow Bypass in the Treatment of Giant/Complex Intracranial Aneurysm: An Opportunity or a Risk from a Fluid-Structural Interaction Analysis

OBJECTIVES

Conventional clipping and endovascular treatment are difficult to apply for some giant intracranial aneurysms (GIAs), and sometimes extracranial-to-intracranial (EC-IC) bypass becomes the optional choice. However, not all GIA patients can benefit from it. This study aims to recognize the underlying problems.

METHODS

We included eligible patients in our care. Then, we researched from three levels: a retrospective review of clinical data, fluid-structural analysis from two representative patient-specific models, and fluid-structural interaction analysis for idealized models to investigate the hemodynamic and biomechanical mechanisms.

RESULTS

In this article, we report nine patients with GIA who underwent EC-IC surgery. Of them, three experienced dangerous postoperative hemorrhage, and one patient died. Among these three patients, two lacked the A1 segment of the anterior cerebral artery (ACA). The numerical simulation showed that after surgery, for the patient with an unruptured aneurysm and existence of ACA, the wall deformation, wall stress, pressure, and area of the oscillatory shear index (OSI) > 0.2 were decreased by 43%, 39%, 33%, and 13%, while the patient without A1 segment having postoperative hemorrhage showed 36%, 45%, 13%, and 55% increased, respectively. Thus, we postulated a dangerous "stump phenomenon" in such conditions and further demonstrated it from idealized models with different sizes of ACA. Finally, we found a larger anastomosis angle and smaller diameter of the graft can alleviate this effect.

CONCLUSIONS

Neurosurgeon should cautiously evaluate the opportunity and risk for such patients who have aplasia of the A1 segment of ACA when making clinical decisions.

Endovascular management of giant post-traumatic pseudoaneurysm in cavernous sinus: A case report

A 20-year-old male was admitted with the history of a traumatic head injury after traffic accident. The physical examination revealed blurred vision, swelling of the right face, and minor epistaxis. CT and MRI findings revealed a giant pseudoaneurysm of cavernous carotid artery. The patient was enrolled endovascular coils embolization of the internal carotid artery. After the procedure, the patient recovered well. Endovascular treatment is an effective therapy in cavernous carotid pseudoaneurysm.

Quantitative analysis of external carotid artery bypass donor vessels by recipient and approach

INTRODUCTION

Utilization an in-situ pedicle of the external carotid artery (ECA) as an arterial donor can allow for the successful augmentation or replacement of flow to a large vascular territory. We propose a mathematical model for quantitatively analyzing and grading the suitability of donor and recipient bypass vessels based on a set of anatomical and surgical variables in order to predict which pair has the greatest possibility for success. Using this method, we analyze all of the potential donor-recipient pairs for each ECA donor vessel-including the superficial temporal (STA), middle meningeal (MMA), and occipital (OA) arteries.

METHODS

The ECA pedicles were dissected in frontotemporal, middle fossa, subtemporal, retrosigmoid, far lateral, suboccipital, supracerebellar, and occipital transtentorial approaches. For each approach, every potential donor-recipient pair was identified, and donor length and diameter were measured as well as depth of field, angle of exposure, ease of proximal control, maneuverability, and length and diameter of the recipient segment. Anastomotic pair scores were determined by adding the weighted donor and recipient.

RESULTS

The best overall anastomotic pairs were OA-vertebral artery (V3, 17.1) and STA-insular (M2, 16.3) and STA-sylvian (M3, 15.9) segments of the middle cerebral artery. Other strong anastomotic combinations were OA- telovelotonsillar (15) and OA- tonsilomedullary (14.9) segments of the posterior inferior cerebellar artery, and MMA-lateral pontomesencephalic segment of the superior cerebellar artery (14.2).

CONCLUSIONS

This novel model for anastamotic pair scoring can serve as a useful clinical tool for selecting the optimal donor, recipient, and approach combination that can help facilitate a successful bypass.

High-flow bypass using saphenous vein grafts with trapping of ruptured blood blister-like aneurysms of the internal carotid artery: patient series

BACKGROUND

Trapping an aneurysm after the establishment of an extracranial to intracranial high-flow bypass is considered the optimal surgical strategy for ruptured blood blister-like aneurysms (BBAs) of the internal carotid artery (ICA). For high-flow bypass surgeries, a radial artery graft is generally preferred over a saphenous vein graft (SVG). However, SVGs can be advantageous in acute-phase surgeries because of their greater length, easy manipulability, ability to act as high-flow conduits, and reduced risk of vasospasms. In this study, the authors presented five cases of ruptured BBAs treated with high-flow bypass using an SVG followed by BBA trapping, and they reported on surgical outcomes and operative nuances that may help avoid potential pitfalls.

OBSERVATIONS

After the surgeries, there were no ischemic or hemorrhagic complications, including symptomatic vasospasms. In three of the five cases, postoperative modified Rankin scale scores were between 0 and 2 at the 3-month follow-up. In one case, the SVG spontaneously occluded after surgery while the protective superficial temporal artery (STA) to middle cerebral artery (MCA) bypass became dominant, and the patient experienced no ischemic symptoms.

LESSONS

High-flow bypass using an SVG with a protective STA-MCA bypass followed by BBA trapping is a safe and effective treatment strategy.

Comparative efficacy of autologous versus cadaveric saphenous vein grafts in cerebral revascularization surgery

OBJECTIVE

Cerebral bypasses are performed for the purpose of either flow augmentation for ischemic cerebrovascular disease or flow replacement for vessel sacrifice during complex aneurysm or tumor surgery. Saphenous vein grafts (SVGs) are commonly used interposition grafts. The authors of this study sought to compare the efficacy of autologous versus cadaveric SVGs in a large series of cerebral bypasses using interposition vein grafts with long-term angiographic follow-up.

METHODS

All intracranial bypass procedures performed between 2001 and 2018 were reviewed. Demographic, clinical, angiographic, and operative data were recorded and then analyzed according to SVG type.

RESULTS

A total of 308 consecutive intracranial bypasses were performed during the study period, 53 (17.2%) of which were bypasses with an interposition SVG (38 autologous, 15 cadaveric). At a median follow-up of 2.2 months (IQR 0.2-29.1), 39 (73.6%) bypasses were patent (26 [68.4%] autologous, 13 [86.7%] cadaveric, p = 0.30). Comparing autologous and cadaveric SVG recipients, there were no statistically significant differences in age (p = 0.50), sex (p > 0.99), history of smoking (p = 0.75), hypertension (p > 0.99), diabetes mellitus (p = 0.13), indication for bypass (p = 0.27), or SVG diameter (p = 0.65). While there were higher intraoperative (autologous, 100.0 ml/min, IQR 84.3-147.5; cadaveric, 80.0 ml/min, IQR 47.3-107.8; p = 0.11) and postoperative (autologous, 142.2 ml/min, IQR 76.8-160.8; cadaveric, 92.0 ml/min, IQR 69.2-132.2; p = 0.42) volumetric flow rates in the autologous SVGs compared to those in the cadaveric SVGs, the difference between the two groups did not reach statistical significance. In addition, the blood flow index, or ratio of postoperative to intraoperative blood flow, for each bypass was similar between the groups (autologous, 1.3, IQR 0.9-1.6; cadaveric, 1.5, IQR 1.0-2.3; p = 0.37). Kaplan-Meier estimates showed no difference in bypass patency rates over time between autologous and cadaveric SVGs (p = 0.58).

CONCLUSIONS

Cadaveric SVGs are a reasonable interposition graft option in cerebral revascularization surgery when autologous grafts are not available.

A Hybrid Strategy for Patients With Complex Cerebral Aneurysm: STA-MCA Bypass in Combination With Endovascular Embolization

Objective: This work aims to present our experience of patients with complex cerebral aneurysm treated with a hybrid approach: superficial temporal artery–middle cerebral artery (STA–MCA) bypass in combination with endovascular exclusion of the aneurysm.

Method: Patients with aneurysms deemed unclippable and uncoilable were included. All patients were treated with a hybrid approach. After STA–MCA bypass, the parent artery was temporarily occluded. If the intraoperative motor evoked potential (MEP) and somatosensory evoked potential (SEP) waveforms remain normal and last for 30 min, the aneurysm and te parent artery will be embolized permanently with detachable balloons or coils.

Results: A total of 20 patients with 22 aneurysms were included in this study. There were 13 women and 7 men, with an average age of 42.5 years. Intraoperative angiography showed the good patency of all the STA grafts, and neither SEP nor MEP abnormalities were detected. After the parent artery and the aneurysm were occluded, the intraoperative angiography showed an immediately successful exclusion of the aneurysm in 20 aneurysms and immediate contrast stasis in two. All patients recovered uneventfully without ischemic or hemorrhagic complication. Angiography at 6-month follow-up showed the total obliteration in 20 aneurysms. Two aneurysms showed residuals and were recoiled. All STA grafts showed a good patency, and the mean graft flow was 124.2 ml/min.

Conclusion: STA–MCA bypass in combination with endovascular exclusion is an appropriate option for patients with complex cerebral aneurysms that are not amenable to direct surgical clipping or endovascular embolization.

Vessel-selective 4D MRA based on ASL might potentially show better performance than 3D TOF MRA for treatment evaluation in patients with intra-extracranial bypass surgery: a prospective study

OBJECTIVES

To compare bypass patency and intracranial collaterals from the external carotid artery (ECA) by four-dimensional MR angiography (MRA) based on super-selective pseudo-continuous arterial spin labeling (pCASL) combined with the keyhole and view-sharing techniques (4D-sPACK) versus three-dimensional time-of-flight (3D TOF) MRA in patients with extra-intracranial revascularization.

METHODS

The MR data of 45 patients administered bypass surgery were collected. The image quality of 4D-sPACK was evaluated using a 4-point grading system according to whether the diagnosis of intracranial collaterals was affected. Anastomosis patency and intracranial collateral visualization from ECA were assessed by two radiologists on 4D-sPACK and 3D TOF MRA, with digital subtraction angiography (DSA) findings as reference. Intracranial collateral assessment employed another 4-point grading system according to the number of vessels shown. Interobserver agreement was assessed with the weighted kappa statistic.

RESULTS

Fifty hemispheres in 43 patients were included. The image quality of 4D-sPACK was good in 47 (47/50, 94.0%) hemispheres. 4D-sPACK had a higher sensitivity than 3D TOF MRA (97.73% vs 79.55%) for visualizing anastomoses. There were significant differences between 4D-sPACK (scores, 3.22 ± 1.15) and 3D TOF MRA (scores, 1.80 ± 0.67) in the visualization of intracranial collaterals from ECA (p < 0.001). The interobserver agreement was substantial for intracranial collateral assessment (κ_4D-sPACK = 0.788; κ_{3D TOF MRA} = 0.800) and almost perfect for bypass patency (κ_4D-sPACK = 0.912; κ_{3D TOF MRA} = 0.816; κ_DSA = 0.811).

CONCLUSION

This pilot study shows that, 4D-sPACK has a better performance than 3D TOF MRA in treatment evaluation of patients after bypass surgery, and has high consistency with DSA.

KEY POINTS

• 4D-sPACK is a non-contrast-enhanced dynamic MRA method for the visualization of intracranial vessels. • 4D-sPACK has higher specificity for the diagnosis of anastomosis occlusion. • 4D-sPACK is better than 3D TOF MRA in the visualization of intracranial collaterals in patients after bypass surgery.

Clinical utility and versatility of the petrous segment of the internal carotid artery in revascularization

Direct approaches to high cervical lesions, including tumors and aneurysms, carry significant risks. This renders alternative approaches desirable, with vascular disease amenable to exclusion and revascularization to the intracranial circulation, including the petrous or supraclinoid segments of the internal carotid artery (ICA). The cervicopetrous ICA bypass via saphenous venous grafting has proven an effective strategy for treating and excluding these lesions. In current practice, this is performed via an extradural subtemporal approach to access the petrous segment of the ICA and a cervical incision for access to the cervical ICA. The venous graft is alternately tunneled subcutaneously or in situ through the cervical ICA, with the latter eschewing external compression, kinking, and torsion, which increases risk of graft thrombosis with the former. Maxillary or middle meningeal arteries may also serve as donors to the petrous ICA. Moreover, the petrous ICA may be used as a donor in revascularization procedures, to the supraclinoid segment of the ICA and the middle cerebral artery, with petrous supraclinoid and petrous-MCA bypasses described. Clinical utility and operative approaches bypassing to or from the petrous ICA in revascularization procedures are reviewed and discussed.

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.

Long-term patency in cerebral revascularization surgery: an analysis of a consecutive series of 430 bypasses

OBJECTIVE

Large cohort analysis concerning intracerebral bypass patency in patients with long-term follow-up (FU) results is rarely reported in the literature. The authors analyzed the long-term patency of extracranial-to-intracranial (EC-IC) and intracranial-to-intracranial (IC-IC) bypass procedures.

METHODS

All intracranial bypass procedures performed between 1997 and 2017 by a single surgeon were screened. Patients with postoperative imaging (CT angiography, MR angiography, or catheter angiography) were included and grouped into immediate (< 7 days), short-term (7 days-1 year), and long-term (> 1 year) FU groups. Data on patient demographics, bypass type, interposition graft type, bypass indication, and radiological patency were collected and analyzed with univariate and multivariate (adjusted multiple regression) models.

RESULTS

In total, 430 consecutive bypass procedures were performed during the study period (FU time [mean ± SD] 0.9 ± 2.2 years, range 0-17 years). Twelve cases were occluded at FU imaging, resulting in an overall cumulative patency rate of 97%. All bypass occlusions occurred within a week of revascularization. All patients in the short-term FU group (n = 76, mean FU time 0.3 ± 0.3 years) and long-term FU group (n = 89, mean FU time 4.1 ± 3.5 years) had patent bypasses at last FU. Patients who presented with aneurysms had a lower rate of patency than those with moyamoya disease or chronic vessel occlusion (p = 0.029). Low-flow bypasses had a significantly higher patency rate than high-flow bypasses (p = 0.033). In addition, bypasses with one anastomosis site compared to two anastomosis sites showed a significantly higher bypass patency (p = 0.005). No differences were seen in the patency rate among different grafts, single versus bilateral, or between EC-IC and IC-IC bypasses.

CONCLUSIONS

The overall bypass patency of 97% indicates a high likelihood of success with microsurgical revascularization. Surgical indication (ischemia), low-flow bypass, and number of anastomosis (one site) were associated with higher patency rates. EC-IC and IC-IC bypasses have comparable patency rates, supporting the use of intracranial reconstructive techniques. Bypasses that remain patent 1 week postoperatively and have the opportunity to mature have a high likelihood of remaining patent in the long term. In experienced hands, cerebral revascularization is a durable treatment option with high patency rates.

Serpentine aneurysm of the posterior cerebral artery treated by internal maxillary artery bypass followed by parent artery occlusion: a case report and literature review

Serpentine aneurysms of the posterior cerebral artery (PCA) treated by the internal maxillary artery (IMA) bypass are rare. Here, the authors report the case of a 34-year-old male patient who presented with a half-year history of gradual severe headache and right-sided limb monoparesis and paresthesia lasting for 1 week. Preoperative angiograms showed a serpentine aneurysm in the left distal PCA, which was treated with internal maxillary artery-radial artery-posterior cerebral artery (IMA-RA-PCA) bypass followed by parent artery occlusion (PAO). The postoperative course was uneventful; radiological images revealed that the aneurysm disappeared, and there was good graft patency and excellent perfusion of the distal PCA territories. To the authors' knowledge, this is the first and only case of distal PCA serpentine aneurysm to be treated by IMA-RA-PCA bypass followed by proximal PAO. These findings suggest that IMA bypass surgery is a good and feasible treatment option for serpentine aneurysms of the PCA that can preserve the parent artery. Moreover, the anatomic segments of the PCA and different treatment options available for PCA serpentine aneurysms are also discussed in this study.

Local in situ fibrinolysis for recanalization of an occluded extracranial-intracranial bypass: Technical note

Extracranial-intracranial (EC-IC) bypass is a versatile technique to augment or preserve blood flow when treating cerebrovascular pathologies to prevent ischemic complications. Technical success and good patient outcomes rely on the successful establishment and maintenance of a patent bypass graft. Multiple modalities have been developed to confirm intraoperative graft patency. However, techniques and strategies to manage an occluded bypass are sparsely reported. The authors describe a novel technique for the in situ fibrinolysis utilizing recombinant tissue plasminogen activator (r-tPA) to recanalize an occluded EC-IC bypass following thrombus formation. This technique is feasible and effective in restoring long term EC-IC graft patency without requirement of additional vessel harvest or added ischemia time which may be tailored for use with other pharmacologic agents based on the acuity of an in-graft thrombosis.

Graft Occlusion and Graft Size Changes in Complex Internal Carotid Artery Aneurysm Treated by Extracranial to Intracranial Bypass Using High-Flow Grafts with Therapeutic Internal Carotid Artery Occlusion

BACKGROUND

Although the extracranial-to-intracranial high-flow bypass (EC-IC HFB) continues to be indispensable for complex aneurysms, the risk factors for the graft occlusion and whether the graft size changes after the bypass have not been well established.

OBJECTIVE

To evaluate the risk factors for the graft occlusion and to confirm whether graft diameters changed over time.

METHODS

The data of 75 patients who suffered from complex internal carotid artery (ICA) aneurysms and were treated by EC-IC HFB using radial artery graft (RAG) or saphenous vein graft (SVG) with therapeutic ICA occlusion were evaluated. Clinical and radiological characteristics were compared in patients with and without the graft occlusion by the log-rank test. Graft diameters measured preoperatively, postoperatively, at 6 months, and at 1 year were compared by paired t-test.

RESULTS

During a follow-up period (median 26.2 months), graft occlusions were seen in 4 patients (5.3%), and these were the SVGs. Only SVG was related to graft occlusion (P < .001). There was a significant increase with time in RAG diameters (preoperative, 3.1 ± 0.41 mm; postoperative, 3.6 ± 0.65 mm; 6 months, 4.3 ± 1.0 mm; 1 year, 4.4 ± 1.0 mm), while there were no significant diameter changes in SVGs.

CONCLUSION

The present study showed that the SVG was related to the graft occlusion and RAGs gradually enlarged. Unless Allen test is negative, RAG may be better to be used as a graft in EC-IC HFB if therapeutic ICA occlusion is needed.

Thrombectomy for late occlusion of high flow extracranial-intracranial saphenous vein bypass graft after 27 years of patency

High flow extracranial-intracranial (EC-IC) bypass with a saphenous vein graft (SVG) has been used for more than 40 years in patients with giant aneurysms of the posterior circulation refractory to medical management, and has demonstrated high long term patency rates. We report the case of a patient treated with external carotid artery (ECA)-posterior cerebral artery SVG bypass in 1989 who presented 27 years later with paresthesias and confusion, and was found to have partial occlusion of her SVG bypass graft and a basilar occlusion. She was treated with mechanical thrombectomy of the basilar occlusion via the partially thrombosed graft, the first report of such a procedure through a high flow posterior circulation EC-IC SVG, resulting in improvement of the patient's neurologic examination. At 27 years, this is the longest reported delay in thrombosis of a high flow SVG bypass graft, highlighting the long term patency of these grafts and the feasibility of thrombectomy through occluded bypass grafts.

Thrombectomy for late occlusion of high flow extracranial-intracranial saphenous vein bypass graft after 27 years of patency

High flow extracranial-intracranial (EC-IC) bypass with a saphenous vein graft (SVG) has been used for more than 40 years in patients with giant aneurysms of the posterior circulation refractory to medical management, and has demonstrated high long term patency rates. We report the case of a patient treated with external carotid artery (ECA)-posterior cerebral artery SVG bypass in 1989 who presented 27 years later with paresthesias and confusion, and was found to have partial occlusion of her SVG bypass graft and a basilar occlusion. She was treated with mechanical thrombectomy of the basilar occlusion via the partially thrombosed graft, the first report of such a procedure through a high flow posterior circulation EC-IC SVG, resulting in improvement of the patient's neurologic examination. At 27 years, this is the longest reported delay in thrombosis of a high flow SVG bypass graft, highlighting the long term patency of these grafts and the feasibility of thrombectomy through occluded bypass grafts.

Late-Onset Massive Epistaxis due to a Ruptured Traumatic Internal Carotid Artery Aneurysm: A Case Report

A traumatic internal carotid artery (ICA) aneurysm is rare and difficult to treat. Trapping of ICA is commonly performed owing to the difficulty of directly approaching ICA aneurysms. Recently, coiling the aneurysm itself was recommended if possible. However, it is controversial which of methods are best to completely treat aneurysm. We present the case of a 74-year-old man, who had experienced a head injury 8 years previously, with recurrent severe epistaxis. An ICA aneurysm was detected on computed tomography. The trapping and bypass was planned. However, sudden epistaxis occurred, we performed trapping to stop the bleeding and save his life. After the operation, no right ICA or aneurysm was detected. However, severe epistaxis recurred two months after the operation. In the second operation, a ligation of the common -/- external carotid artery and a severance of an ICA portion between the ophthalmic artery and the aneurysm were insufficient to stop the bleeding. This case indicates ICA trapping, even if a trapping portion is below an ophthalmic artery, is insufficient to treat an ICA aneurysm. ICA aneurysms should be suspected when a patient present with recurrent -/- massive epistaxis, who has a head injury history, even if it is far past.

Surgical Technique for High-Flow Internal Maxillary Artery to Middle Cerebral Artery Bypass Using a Superficial Temporal Artery Interposition Graft

BACKGROUND: Extracranial-to-intracranial high-flow bypass often requires cranial, cervical, and graft site incisions. The internal maxillary artery (IMA) has been proposed as a donor to decrease invasiveness, but its length is insufficient for direct intracranial bypass. We report interposition of a superficial temporal artery (STA) graft for high-flow IMA to middle cerebral artery (MCA) bypass using a middle fossa approach.

OBJECTIVE: To assess the feasibility of an IMA–STA graft-MCA bypass using a new middle fossa approach.

METHODS: Twelve specimens were studied. A 7.5-cm STA graft was obtained starting 1.5 cm below the zygomatic arch. The calibers of STA were measured. After a pterional craniotomy, the IMA was isolated inside the infratemporal fossa through a craniectomy within the lateral triangle (lateral to the posterolateral triangle) in the middle fossa and transposed for proximal end-to-end anastomosis to the STA. The Sylvian fissure was split exposing the insular segment of the MCA, and an STA-M2 end-to-side anastomosis was completed. Finally, the length of graft vessel was measured.

RESULTS: Average diameters of the proximal and distal STA ends were 2.3 ± 0.2 and 2.0 ± 0.1 mm, respectively. At the anastomosis site, the diameter of the IMA was 2.4 ± 0.6 mm, and the MCA diameter was 2.3 ± 0.3 mm. The length of STA graft required was 56.0 ± 5.9 mm.

CONCLUSION: The STA can be used as an interposition graft for high-flow IMA–MCA bypass if the STA is obtained 1.5 cm below the zygomatic arch and the IMA is harvested through the proposed approach. This procedure may provide an efficient and less invasive alternative for high-flow EC–IC bypass.

Measurement of Blood Flow in an Intracranial Artery Bypass From the Internal Maxillary Artery by Intraoperative Duplex Sonography

This study explored the hemodynamic characteristics of a subcranial-intracranial bypass from the internal maxillary artery by measuring blood flow on intraoperative duplex sonography. The hemodynamic parameters of the internal maxillary artery (n = 20), radial artery (n = 20), internal maxillary artery-middle cerebral artery bypass (n = 42), and internal maxillary artery-posterior cerebral artery bypass (n = 9) were measured by intraoperative duplex sonography. There was no significant difference in the internal diameters of the internal maxillary and radial arteries (mean ± SD, 2.51 ± 0.34 versus 2.56 ± 0.22 mm; P = .648). The mean radial artery graft length for subcranial-intracranial bypasses was 88.5 ± 12.78 mm (95% confidence interval [CI], 80.8-90.2 mm). Internal maxillary artery-middle cerebral artery bypasses required a shorter radial artery graft than internal maxillary artery-posterior cerebral artery bypasses (77.8 ± 2.47 versus 104.8 ± 4.77 mm; P = .001). The mean flow volumes were 85.3 ± 18.5 mL/min (95% CI, 76.6-93.9 mL/min) for the internal maxillary artery, 72.6 ± 26.4 mL/min (95% CI, 64.3-80.9 mL/min) for internal maxillary artery-middle cerebral artery bypasses, and 45.4 ± 6.7 mL/min (95% CI, 40.7-50.0 mL/min) for internal maxillary artery-posterior cerebral artery bypasses. All grafts were opened after the success of the salvage procedures had been established, and the early patency rates (1 month after the operation) were 95% for internal maxillary artery-middle cerebral artery bypasses and 100% the internal maxillary artery-posterior cerebral artery bypasses. Measurement of blood flow by intraoperative sonography can be helpful in decision making and predicting graft patency and success after neurosurgical bypass procedures.

Risk factors for neurological worsening and symptomatic watershed infarction in internal carotid artery aneurysm treated by extracranial-intracranial bypass using radial artery graft

OBJECT

The revascularization technique, including bypass created using the external carotid artery (ECA), radial artery (RA), and M2 portion of middle cerebral artery (MCA), has remained indispensable for treatment of complex aneurysms. To date, it remains unknown whether diameters of the RA, superficial temporal artery (STA), and C2 portion of the internal carotid artery (ICA) and intraoperative MCA blood pressure have influences on the outcome and the symptomatic watershed infarction (WI). The aim of the present study was to evaluate the factors for the symptomatic WI and neurological worsening in patients treated by ECA-RA-M2 bypass for complex ICA aneurysm with therapeutic ICA occlusion.

METHODS

The authors measured the sizes of vessels (RA, C2, M2, and STA) and intraoperative MCA blood pressure (initial, after ICA occlusion, and after releasing the RA graft bypass) in 37 patients. Symptomatic WI was defined as presence of the following: postoperative new neurological deficits, WI on postoperative diffusion-weighted imaging, and ipsilateral cerebral blood flow reduction on SPECT. Neurological worsening was defined as the increase in 1 or more modified Rankin Scale scores. First, the authors performed receiver operating characteristic curve analysis for continuous variables and the binary end point of the symptomatic WI. The clinical, radiological, and physiological characteristics of patients with and without the symptomatic WI were compared using the log-rank test. Then, the authors compared the variables between patients with and without neurological worsening at discharge and at the 12-month follow-up examination or last hospital visit.

RESULTS

Symptomatic WI was observed in 2 (5.4%) patients. The mean MCA pressure after releasing the RA graft (< 55 mm Hg; p = 0.017), mean (MCA pressure after releasing the RA graft)/(initial MCA pressure) (< 0.70 mm Hg; p = 0.032), and mean cross-sectional area ratio ([RA/C2 diameter]2 < 0.40 mm [p < 0.0001] and [STA/C2 diameter]2 < 0.044 mm [p < 0.0001]) were related to the symptomatic WI. All preoperatively independent patients remained independent (modified Rankin Scale score < 3). After adjusting for age and sex, left operative side (p = 0.0090 and 0.038) and perforating artery ischemia (p = 0.0050 and 0.022) were related to neurological worsening at discharge (11 [29%] patients) and at the 12-month follow-up or last hospital visit (8 [22%] patients).

CONCLUSIONS

Results of the present study showed that the vessel diameter and intraoperative MCA pressure had impacts on the symptomatic WI and that operative side and perforating artery ischemia were related to neurological worsening in patients with complex ICA aneurysms treated by ECA-RA-M2 bypass.

Donor Selection in Flow Replacement Bypass Surgery for Cerebral Aneurysms: Quantitative Analysis of Long-term Native Donor Flow Sufficiency

BACKGROUND:

Graft selection in extracranial-intracranial bypass surgery for cerebral aneurysms has traditionally been based on clinical impression and operator preference. However, decision making can be optimized with a donor selection algorithm based on intraoperative flow data.

OBJECTIVE:

To present long-term follow-up and quantitative assessment of flow sufficiency for native donors selected in this manner.

METHODS:

Patients with bypass for anterior circulation intracranial aneurysms using only a native donor (superficial temporal artery) selected on the basis of an intraoperative flow algorithm over a 10-year period were retrospectively studied. Intracranial hemispheric and bypass flows were assessed preoperatively and postoperatively when available with quantitative magnetic resonance angiography.

RESULTS:

Twenty-two patients with flow data were included (median aneurysm size, 22 mm). The intraoperative flow offer (cut flow) of the superficial temporal artery was sufficient in these cases relative to the flow demand in the sacrificed vessel (59 vs 28 mL/min) to warrant its use. Bypass flow averaged 81 mL/min postoperatively (n = 19). Bypass flows were highest in the immediate postoperative period but remained stable between the intermediate and final follow-up (40 vs 52 mL/min; P = .39; n = 8). Mean ipsilateral hemisphere flows were maintained after bypass (299 vs 335 mL/min; P = .42; n = 7), and remained stable over intermediate and long-term follow-up. Ipsilateral hemispheric flows remained similar to contralateral flows at all time points.

CONCLUSION:

Despite a relative reduction in bypass flow over time, hemispheric flows were maintained, indicating that simple native donors can carry sufficient flow for territory demand long term when an intraoperative flow-based algorithm is used for donor selection.

Forearm Cephalic Vein Graft for Short, “Middle”-Flow, Internal Maxillary Artery to Middle Cerebral Artery Bypass

BACKGROUND

The cervical carotid system has been used as a source of donor vessels for radial artery or saphenous vein grafts in cerebral bypass. Recently, internal maxillary artery to middle cerebral artery bypass has been described as an alternative, with reduction of graft length potentially correlating with improved patency.

OBJECTIVE

To describe our experience using the forearm cephalic vein grafts for short segment internal maxillary artery to middle cerebral artery bypasses.

METHODS

All vein grafts were harvested from the volar forearm between the proximal cubital fossa where the median cubital vein is confluent with the cephalic vein and the distal wrist.

RESULTS

Six patients were treated with internal maxillary artery to middle cerebral artery bypass. In 4, the cephalic vein was used. Postoperative angiography demonstrated good filling of the grafts with robust distal flow. There were no upper extremity vascular complications. All but 1 patient (mortality) tolerated the procedure well. The other 3 patients returned to their neurological baseline with no new neurological deficit during follow-up.

CONCLUSION

The internal maxillary artery to middle cerebral artery “middle” flow bypass allows for shorter graft length with both the proximal and distal anastomoses within the same microsurgical field. These unique variable flow grafts represent an ideal opportunity for use of the cephalic vein of the forearm, which is more easily harvested than the wider saphenous vein graft and which has good match size to the M1/M2 segments of the middle cerebral artery. The vessel wall is supple, which facilitates handling during anastomosis. There is lower morbidity potential than utilization of the radial artery. Going forward, the cephalic vein will be our preferred choice for external carotid-internal carotid transplanted conduit bypass.

Radial Artery Bypass for Intractable Vertebrobasilar Insufficiency: Case Series and Review of the Literature

BACKGROUND

Vertebrobasilar insufficiency resulting from embolism, atherosclerosis, or arterial dissection has long been a challenge for successful management and outcomes. The main treatment options include medical therapy, angioplasty and stenting, and surgical revascularization. Unlike cardiac or peripheral vascular revascularization, large randomized trials with cerebrorevascularization have not revealed favorable outcomes. In patients who have failed maximal medical therapy, and having persistent debilitating symptomology, cerebral revascularization may still be a viable option.

METHODS

We report 3 patients who presented with symptoms of vertebrobasilar ischemia. The diagnosis was verified by computerized tomographic arteriography and digital subtraction angiography.

RESULTS

These patients subsequently underwent revascularization with a radial artery graft. We also present a comprehensive review of the literature of treatment for vertebrobasilar insufficiency.

CONCLUSIONS

Surgical revascularization should be considered in the posterior circulation in the rare subset of patients with VBI, who remain symptomatic despite having a protracted course of maximal medical therapy with large- and medium-sized vessel occlusions and poor collateral circulation.

Giant and complex aneurysms treatment with preservation of flow via bypass technique

Due to their anatomical characteristics and the complexity of the procedures required to obtain their complete occlusion, the treatment of giant intracranial aneurysms is a real challenge. Direct reconstructive strategies, whether by interventional neuroradiology (coils, stents) or microsurgical (clipping) means, are not always applicable and, in patients that would not tolerate parent or collateral artery sacrifice, the adjunction of a revascularization procedure using a bypass technique might be necessary. Cerebral arterial bypasses can be classified according to their function (3 types: flow replacement, flow reversal or protective), the branching mode of the graft used (3 types: pedicled, interpositional or in situ), the sites of anastomosis (2 types: extracranial-intracranial or intracranial-intracranial) and the class of flow they are supposed to provide (3 types: low-, intermediate- or high-flow). In this article, the authors review the different aspects in the management of patients with a giant intracranial aneurysm using a bypass: preoperative work-up, types of bypass and indications, surgical techniques and results.

Viability of anastomoses with coupler in extra-intracranial bypass: cadaveric study

BACKGROUND

The time required to perform an anastomosis in extra-intracranial bypass is approximately 20 to 60 minutes. The search for alternative methods to reduce the ischemic time remains vital.

OBJECTIVE

To evaluate Coupler anastomosis for extra-intracranial bypass in cadavers.

METHODS

In 8 fresh adult cadavers, the saphenous vein and radial artery were used as donor vessels. The superficial temporal and the extracranial internal and external carotid arteries were dissected. A wide craniotomy with a sylvian fissure opening was performed, exposing the middle cerebral and supraclinoid internal carotid arteries. The Coupler devices were tested in all 8 cadavers. The diameter of the donor and recipient vessels as well as the time required to perform the anastomosis were measured. Bypass permeability was evaluated by injecting saline solution under pressure, checking for leaks.

RESULTS

The anastomoses were successfully performed in all specimens. The size of the head of the fitting Coupler required the performance of a wide craniotomy (6 × 6 cm) and a wide opening of the sylvian fissure. The time required to perform each anastomosis ranged from 4 to 7 minutes, being easier with the radial artery than with the saphenous vein.

CONCLUSION

Coupler devices are helpful to perform the anastomoses, because they significantly reduce ischemia time. Their use is easier at the M1 segment, just before the bifurcation and after takeoff of the lenticulostriate arteries, and in the M2 segment. It would be advisable to have a smaller coupling system, allowing maneuverability in the deeper areas where space is limited.

Cavernous sinus meningiomas: imaging and surgical strategy

Cavernous sinus (CS) meningiomas which are by definition those meningiomas which originate from the parasellar region are difficult skull base tumors to deal with. For deciding the most appropriate surgical strategy, surgeons need detailed preoperative neuroimaging. The vicinity of the tumor with the vital and highly functional neurovascular structures, tumor extensions into the basal cisterns and skull base structures, and the arterial vascularization and venous drainage pathways, as they shape operative strategy, are important preoperative data to take into account. Thin section CT scan with bone windows, 3D spiral CT reconstruction, MRI, MR angiography, and DSA performed with selective arteriography including late venous phases give those required detailed informations about the tumor and its relation with neurovascular and bony structures. The type of craniotomy and complementary osteotomy and the usefulness of an extradural anterior clinoidectomy with unroofing the optic canal can be decided from preoperative neuroimaging. Data collected also help in determining whether extensive exposure of the middle cranial fossa is necessary to ensure substantial devascularization of the tumor and whether proximal control of the internal carotid artery (ICA) at its intrapetrosal portion might be useful. Study of the capacity of blood supply of the Willis circle is wise for deciding the need and way of performing an extra-intracranial bypass together with tumor removal. Currently the concept of operating only the tumors with extracavernous extensions and to limit resection to only their extracavernous portions is the most accepted way of treating these tumors. It was that strategy that was adopted in the senior author's 220-patient series.Radiosurgery or stereotactic fractionated radiotherapy may complement surgery or can be only reserved for growing remnants.

Advances in Open Microsurgery for Cerebral Aneurysms

BACKGROUND:

Endovascular techniques introduced strong extrinsic forces that provoked reactive changes in aneurysm surgery. Microsurgery has become less invasive, more appealing to patients, lower risk, and efficacious for complex aneurysms, particularly those unfavorable for or failing endovascular therapy.

OBJECTIVE:

To review specific advances in open microsurgery for aneurysms.

METHODS:

A university-based, single-surgeon practice was examined for the use of minimally invasive craniotomies, surgical management of recurrence after coiling, the use of intracranial-intracranial bypass techniques, and cerebrovascular volume-outcome relationships.

RESULTS:

The mini-pterional, lateral supraorbital, and orbital-pterional craniotomies are minimally invasive alternatives to standard craniotomies. Mini-pterional and lateral supraorbital craniotomies were used in one-fourth of unruptured patients, increasing from 22% to 28%, whereas 15% of patients underwent orbital-pterional craniotomies and trended upward from 11% to 20%. Seventy-four patients were treated for coil recurrences (2.3% of all aneurysms) with direct clip occlusion (77%), clip occlusion after coil extraction (7%), or parent artery occlusion with bypass (16%). Intracranial-intracranial bypass (in situ bypass, reimplantation, reanastomosis, and intracranial grafts) transformed the management of giant aneurysms and made the surgical treatment of posterior inferior cerebellar artery aneurysms competitive with endovascular therapy. Centralization maximized the volume-outcome relationships observed with clipping.

CONCLUSION:

Aneurysm microsurgery has embraced minimalism, tailoring the exposure to the patient's anatomy with the smallest possible craniotomy that provides adequate exposure. The development of intracranial-intracranial bypasses is an important advancement that makes microsurgery a competitive option for complex and recurrent aneurysms. Trends toward centralizing aneurysm surgery in tertiary centers optimize results achievable with open microsurgery.

Monitoring Flow in Extracranial-Intracranial Bypass Grafts Using Duplex Ultrasonography: A Single-Center Experience in 80 Grafts Over 8 Years

BACKGROUND:

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.

OBJECTIVE:

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.

METHODS:

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.

RESULTS:

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 &gt;200 mL/min was 100% sensitive to cerebral hyperemia syndrome.

CONCLUSION:

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.

Extracranial-intracranial bypass of the bilateral anterior cerebral circulation using a thoracodorsal axis artery-graft

Bilateral extracranial-intracranial (EC-IC) bypass-grafting of the cerebral circulation is uncommon. We report a case of anterior cerebral artery EC-IC bypass using the thoracodorsal axis artery-graft. The bifurcation of the thoracodorsal axis allows bypass of both anterior hemispheres, while matching appropriate small-vessel dimensions.

Extracranial-Intracranial Bypass and Vessel Occlusion for the Treatment of Unclippable Giant Middle Cerebral Artery Aneurysms

BACKGROUND:

Giant middle cerebral artery (MCA) aneurysms pose management challenges.

OBJECTIVE:

To review the outcomes of patients with giant MCA aneurysms not amenable to clipping or vessel reconstruction treated with extracranial-intracranial (EC-IC) bypass and vessel sacrifice.

METHODS:

We retrospectively reviewed a database of aneurysms treated at our institution between 1983 and 2011.

RESULTS:

Sixteen patients (11 males, 5 females) were identified. There were 10 saccular, 4 fusiform, and 2 serpentine aneurysms. The aneurysms predominantly involved the M1 segment in 5 cases, M2 in 9 cases, and both M1 and M2 in 2 cases. The EC-IC bypasses performed included 13 superficial temporal artery-MCA, 1 saphenous vein graft-MCA, and 2 radial artery grafts-MCA. The postoperative bypass patency rate was 93.8% (15/16). There were 3 cerebrovascular accidents (18.8%), but no perioperative deaths (0% mortality). The mean follow-up was 58.4 months (range, 1-265; median, 23.5 months). In 75% (12/16) of cases the aneurysms were occluded successfully. A small residual was noted in 3 cases with the use of this treatment strategy, and they were re-treated. In a fourth case treated with partial distal occlusion, reduced flow through the aneurysm was noted postoperatively, but the patient did not undergo further treatment. The mean modified Rankin scale and mean Glasgow Outcome Scale scores at last follow-up were 1.6 (range, 1-4; median, 1) and 4.8 (range, 3-5; median, 5), respectively.

CONCLUSION:

Giant MCA aneurysms are challenging lesions. EC-IC bypass with parent vessel occlusion can provide a durable form of treatment with acceptable rates of morbidity and mortality.

Cerebral bypasses for complex aneurysms and tumors: long-term results and graft management strategies

BACKGROUND

Various techniques of cerebral bypasses are used to treat aneurysms and tumors.

OBJECTIVE

To study long-term clinical and radiological outcome of various bypass types and to analyze techniques used in the management of long-term graft problems.

METHODS

A consecutive series of patients who underwent revascularization during a 5-year period were analyzed for indications, graft patency, and neurological outcomes. Potential risk factors for bypass problems and the management of bypass stenosis were studied.

RESULTS

A total of 80 patients (69 with aneurysms and 11 with tumors) underwent 88 bypasses (59 extracranial-to-intracranial [EC-IC] bypasses [10 low flow, 49 high flow], 9 intracranial-to-intracranial [IC-IC] bypasses [3 long, 6 short], and 20 local bypasses), with mean radiological follow-up of 32 months (range, 1-53 months). At late follow-up, 5 of 9 (56%) IC-IC (5 short, 0 long grafts), 8 of 9 (90%) EC-IC low-flow, 44 of 48 (92%) EC-IC high-flow, and all local bypasses were patent. Four patients with EC-IC high-flow bypass occlusions were asymptomatic, but transient ischemic attacks were noted in 3 of 6 patients with graft stenosis. None of the risk factors evaluated were significantly predictive of EC-IC graft occlusions or stenosis. EC-IC HF graft stenoses were permanently corrected by microsurgery (n = 4) or endovascular surgery (n = 1).

CONCLUSION

The EC-IC and local bypasses have higher long-term patency rates (91% and 100%) compared with IC-IC bypasses (66%, 0% long graft). Some EC-IC bypasses may occlude asymptomatically (9%) or develop graft stenosis (13%) over the long term. Microsurgical and endovascular surgical techniques have been developed to treat graft stenosis.

Mean Arterial Pressure Required for Maintaining Patency of Extracranial-to-Intracranial Bypass Grafts

BACKGROUND:

Maintaining flow in a newly established high-flow bypass into the intracranial circulation may be threatened by low blood pressure.

OBJECTIVE:

To identify mean arterial blood pressure below which early graft failure may ensue.

METHODS:

Computational fluid dynamic blood flow simulation and Doppler ultrasound–derived velocities were combined to study 12 patients with common carotid–to–intracranial (internal carotid artery in 9 and middle cerebral artery in 3) arterial brain bypass with interposition of the saphenous vein. Patients underwent carotid duplex and high-resolution computed tomography angiography to obtain the necessary data. A mean time-averaged pressure gradient across both anastomoses of the graft was then calculated.

RESULTS:

The bypass graft mean blood flow ± SD was 180.3 ± 76.2 mL/min (95% confidence interval: 132–229). The mean time-averaged pressure gradient ± SD across the bypass graft was 10.2 ± 8.7 mm Hg (95% confidence interval: 4.6-15.7). This compared with a mean pressure gradient ± SD on the contralateral carotid of 21.7 ± 13.8 mm Hg. From these data, the minimum mean ± SD systemic pressure necessary to maintain graft flow of at least 40 mL/min was 61.6 ± 2.31 mm Hg, and the mean peak wall shear stress ± SD at the proximal anastomosis was 0.8 ± 0.7 Pa (95% confidence interval: 0.3-1.2).

CONCLUSION:

Early postoperative mean arterial pressure less than approximately 60 mm Hg may induce blood flow in the bypass to decrease to less than 40 mL/min, a flow below which low shear stress may lead to early graft occlusion.

Safety of early endovascular catheterization and intervention through extracranial-intracranial bypass grafts

Object

The goal of this study was to demonstrate feasibility and evaluate technical aspects of early endovascular access through extracranial-intracranial (EC-IC) bypass grafts.

Methods

Patients undergoing endovascular interventions through the graft in the acute postoperative period following EC-IC bypass are presented. Results, complications, and technical nuances are reviewed.

Results

Fourteen endovascular procedures were performed in 5 patients after EC-IC bypass for ruptured aneurysms in 4 patients and posterior circulation ischemia in 1 patient. In 2 patients, a saphenous vein graft (SVG) was used to bypass the common carotid artery (CCA) to the middle cerebral artery (MCA). One patient underwent a superficial temporal artery (STA)–MCA bypass, and in 2 other patients the STA stump was connected to the intracranial circulation via an interposition SVG. The interval from surgery to endovascular intervention spanned 2–18 days; the indication was intracranial vasospasm in all patients. One case involved angioplasty of the proximal anastomosis on postoperative Day 14. All other interventions entailed proximal access through the bypass conduit for intraarterial infusion of vasodilators. Significant vasospasm of the STA itself was encountered in 2 patients during endovascular manipulation, and it was treated with intraarterial nitroglycerin. There were no cases of anastomotic disruption.

Conclusions

Endovascular catheterization and intervention involving a recent EC-IC bypass is feasible. The main limitation in this series was catheter-induced vasospasm involving the STA. A vein graft may be the more appropriate option in patients with subarachnoid hemorrhage who may require subsequent endovascular intervention for vasospasm.

High-flow extracranial-to-intracranial excimer laser-assisted nonocclusive anastomosis bypass for symptomatic carotid artery occlusion

BACKGROUND

A high-flow bypass is theoretically more effective than a conventional low-flow bypass in preventing strokes in patients with symptomatic carotid artery occlusion and a compromised hemodynamic state of the brain.

OBJECTIVE

To study the results of excimer laser-assisted nonocclusive anastomosis (ELANA) high-flow extracranial-to-intracranial (EC-IC) bypass surgery in these patients.

METHODS

Between August 1998 and May 2008, 24 patients underwent ELANA EC-IC bypass surgery because of transient ischemic attacks or minor ischemic stroke associated with carotid artery occlusion. We retrospectively collected information. Follow-up data were updated by structured telephone interviews between May and September 2008.

RESULTS

In all patients, the ELANA EC-IC bypass was patent at the end of surgery with a mean flow of 106 ± 41 mL/min. Within 30 days after the operation, 22 patients (92%) had no major complication, whereas 2 patients (8%) had a fatal intracerebral hemorrhage. During follow-up of a mean 4.4 ± 2.4 years, the bypass remained patent in 18 of the 22 surviving patients (82%) with a mean flow of 141 ± 59 mL/min. All patients with a patent bypass remained free of transient ischemic attacks and ischemic stroke. In 4 patients, the bypass occluded, accompanied by ipsilateral transient ischemic attacks in 2 patients, ipsilateral ischemic stroke in 1 patient, and contralateral ischemic stroke in another patient.

CONCLUSION

ELANA EC-IC bypass surgery in patients with carotid artery occlusion is technically feasible and results in cessation of ongoing transient ischemic attacks and minor ischemic strokes, but carries a risk of postoperative hemorrhage.

Revascularization for complex cerebral aneurysms

BACKGROUND AND PURPOSE

Complex cerebral aneurysms may require indirect treatment with revascularization. This manuscript describes various surgical revascularization techniques together with clinical outcomes.

METHODS

Thirty-two consecutive patients with complex cerebral aneurysm were managed from November 2005 to October 2008. Techniques used for revascularization were high-flow bypass, low-flow bypass, branch artery reimplantion, and primary reanastomosis. Physiologic and anatomic monitoring technologies, including electroencephalography, somatosensory evoked potential monitoring, microvascular doppler ultrasonography, and/or indocyanine green videoangiography were used intraoperatively to assess both brain physiology and vascular anatomy. Patient outcome was determined using the Glasgow Outcome Scale at discharge and at a mean of 12 months post operation (range 6-25 months).

RESULTS

Two cervical carotid aneurysms (6%) were resected followed by primary reanastomosis, 21 aneurysms (66%) were trapped following saphenous vein high-flow bypasses, five (16%) were clipped after superficial temporal or occipital artery low-flow bypasses, and four (12%) middle cerebral branch arteries were reimplanted. Of the 32 patients at discharge, 29 (91%) had a Glasgow Outcome Scale of four or five, two (6%) had severe disability, and one (3%) died.

CONCLUSION

Cerebral revascularization remains an effective and reliable procedure for treatment of complex cerebral aneurysms. Low morbidity and mortality rates reflect the maturity of patient selection and surgical technique in the management of these lesions.

KIS, Zhang Y, Zhou Z, Sun Y. Bypass of the maxillary to proximal middle cerebral artery or proximal posterior cerebral artery with radial artery graft

The authors report three cases of radial artery (RA) graft bypass from the maxillary artery (MA) to either the middle cerebral artery (MCA) or the posterior cerebral artery (PCA). The first two cases presented with the features of basal ganglion ischemia, and magnetic resonance imaging (MRI) revealed left and right basal ganglion ischemia respectively, whereas angiogram showed MCA occlusion. Computed tomography angiography (CTA) of the third case, who presented with headache and dysphasia, showed a giant basilar artery aneurysm with an absence of the left posterior communicating artery (PComA). The first two cases underwent MA-MCA graft bypass and the third case underwent MA-posterior cerebral artery (PCA) RA graft bypass, followed by clipping of the left dominance vertebral artery and a sub-occipital decompressive craniotomy. Postoperative angiogram disclosed patent RA graft and refilling of the ischemic segment. Follow-up at 7-9 months showed marked clinical improvement in all cases. To our knowledge, MA bypass has not been performed clinically till the date and this method may be a safe, effective and new surgical technique for the extracranial-intracranial (EC-IC) bypass surgery.

Indocyanine green videoangiography for confirmation of bypass graft patency

OBJECTIVE

The aim of the study is to determine the efficacy of indocyanine green (ICG) videoangiography for confirmation of vascular anastomosis patency in both extracranial-intracranial and intracranial-intracranial bypasses.

METHODS

Intraoperative ICG videoangiography was used as a surgical adjunct for 56 bypasses in 47 patients to assay the patency of intracranial vascular anastomosis. These patients underwent a bypass for cerebral ischemia in 31 instances and as an adjunct to intracranial aneurysm surgery in 25. After completion of the bypass, ICG was administered to assess the patency of the graft. The findings on ICG videoangiography were then compared to intraoperative and/or postoperative imaging.

RESULTS

ICG provided an excellent visualization of all cerebral arteries and grafts at the time of surgery. Four grafts were determined to be suboptimal and were revised at the time of surgery. Findings on ICG videoangiography correlated with intraoperative and/or postoperative imaging.

CONCLUSION

ICG videoangiography is rapid, effective, and reliable in determining the intraoperative patency of bypass grafts. It provides intraoperative information allowing revision to reduce the incidence of technical errors that may lead to early graft thrombosis.

Experience in Using the Excimer Laser–Assisted Nonocclusive Anastomosis Nonocclusive Bypass Technique for High-Flow Revascularization

BACKGROUND

The excimer laser–assisted nonocclusive anastomosis (ELANA) technique enables large-caliber bypass revascularization without temporary occlusion of the parent artery.

OBJECTIVE

To present the surgical experience of 2 bypass centers using ELANA in the treatment of complex intracranial lesions.

METHODS

Between July 2002 and December 2007, 64 consecutive patients (37 in Germany and 27 in Finland) were selected for high-flow bypass surgery with ELANA. Modified Rankin Scale, a bypass success rate, and the success rate of the laser arteriotomy were assessed.

RESULTS

In 66 surgeries for 64 intent-to-treat patients, 58 ELANA procedures were completed successfully. A favorable outcome (postoperative modified Rankin Scale score less than or equal to preoperative modified Rankin Scale) at 3 months was achieved in 43 of 56 patients (77%) with anterior circulation lesions (37 of the 43 patients had aneurysms, 4 had ischemia, and 2 received a bypass before tumor removal) and only in 2 of 8 patients (25%) with posterior circulation aneurysms. Perioperative (&lt; 7 days) mortality for anterior and posterior circulation aneurysms was 6% and 50%, respectively. At the 3-month follow-up, 12% and 63% of patients with anterior and posterior circulation aneurysms, respectively, were dead. The success rate of the laser arteriotomy was 70%. Another 14% were retrieved manually after a nearly complete laser arteriotomy.

CONCLUSION

The ELANA procedure requires a meticulous and careful operative technique. Morbidity and especially mortality rates, usually unrelated to ELANA, are comparable to those of contemporary series of conventional high-flow revascularization operations. This underscores the overall complexity of treating neurovascular pathologies by high-flow bypasses.

Intracranial aneurysms in adolescents

PURPOSE

Intracranial aneurysms are extremely uncommon in adolescents. This study was undertaken to assess the clinical and radiological characteristics and clarify the choice of therapeutic strategies of intracranial aneurysms in adolescents with age range from 15 to 18 years.

METHODS

From our dedicated aneurysmal databank between October 1985 and July 2008, we reviewed 16 consecutive adolescents who had 20 intracranial aneurysms.

RESULTS

Ten boys and six girls (male/female ratio = 1.67:1; mean age 16.78 ± 1.18 years) were included in the present study. Intracranial aneurysms in adolescents constituted 0.91% of all intracranial aneurysms. It was found that 25% of the lesions were in the posterior circulation, while 75% of the lesions were in the anterior circulation, and 25% developed on the middle cerebral artery (MCA). Half of the patients presented with subarachnoid hemorrhage and others mainly presented with mass effect such as weakness in the extremities, diplopia, and dysfunction of eye movement. Eight cases underwent endovascular treatment: including GDC therapy in five patients, parental artery occlusion in two patients, and cover stent implantation in one patient with pseudoaneurysm of the cavernous segment of the left internal carotid artery. Four patients received microsurgical therapy: aneurismal neck clipping for two patients and extracranial-intracranial (EC-IC) bypass and trapping of complex aneurysms in MCA for the other two patients. Four patients did not receive microsurgical or endovascular therapy, including a boy whose aneurysm spontaneously thrombosed preoperatively and a girl who died before operation because of rerupture of aneurysm. Two patients did not undergo therapy owing to the high operative risk. All of the patients who received therapy had favorable outcome (GOS 4 or 5) at discharge and at follow-up.

CONCLUSIONS

Intracranial aneurysms in adolescents differ from those in adults in many ways including the following: male predominance; high incidence of large or giant, traumatic, dissecting, and fusiform aneurysms; high incidence of aneurysms in the posterior circulation; high incidence of spontaneous thrombosis; better Hunt-Hess grade at presentation; and better therapeutic outcome. Both microsurgical approaches and endovascular treatment were effective. For some giant, complex intracranial aneurysms, parent artery occlusion or EC-IC bypass is the best treatment choice.

Endovascular stenting of an extracranial-intracranial saphenous vein high-flow bypass graft: Technical case report

Background:

The authors describe a case of endovascular stenting of an extracranial–intracranial saphenous vein high-flow bypass graft in the management of a complex bilateral carotid aneurysm case.

Case Description:

A 43-year-old woman was admitted with progressive visual field restriction and headache. Imaging studies revealed bilateral supraclinoid carotid aneurysms. The right carotid aneurysm was clipped and the left one was treated by an endovascular procedure, after performing an internal carotid artery–middle cerebral artery (ICA-MCA) saphenous vein bypass graft. A few months following the bypass procedure, a 70–80% stenosis of the graft was discovered and treated endovascularly with a stenting procedure. Follow-up at 36 months after the first operation showed the patency of the venous graft and no neurological deficits.

Conclusions:

Endovascular stenting of the extracranial–intracranial saphenous vein high-flow bypass graft is technically feasible when postoperative graft occlusion is discovered.

Comparative Patency Between Intracranial Arterial Pedicle and Vein Bypass Surgery

BACKGROUND:

Long-term patency of extracranial-to-intracranial (EC-IC) vein bypass is poorly understood.

OBJECTIVE:

We report our experience of patency of arterial pedicle grafts and interposition vein grafts for the purpose of EC-IC bypass.

METHODS:

We analyzed 294 consecutive patients who underwent 178 intracranial arterial pedicle bypass procedures and 152 intracranial vein bypass procedures. Bypass patency was assessed by digital subtraction angiography, computed tomographic angiography, and/or Doppler ultrasound. The modified Rankin Scale (mRS) was assigned for clinical grading at the last follow-up consultation.

RESULTS:

The main indication for arterial pedicle bypass surgery was internal carotid artery occlusion (79 cases); for vein bypass surgery, it was giant aneurysms (61 cases). Procedure-related complications due to surgery occurred in 3 cases (1.7%; 95% CI: 0.4-5.1%) of arterial pedicle bypass surgery and 12 cases (7.9%; 95% CI: 4.5-13.4%) of vein bypass surgery. The patency rate at 6 weeks was 98% (95% CI: 95.0-99.7%) for arterial pedicle bypass and 93% (95% CI: 87.4-96%) for vein bypass, with almost all graft failures occurring within the first week following surgery. Beyond the first week, bypass patency was similar for both groups, with both arterial pedicle grafts and vein bypass grafts that were patent at 1 week having a long-term patency of 99%. There was no statistically significant difference in early, late, and overall patency between the 2 bypass groups.

CONCLUSION:

The surgical complication rate was greater for vein bypass. Both arterial pedicle and vein bypass have good long-term patency.

The sutureless excimer laser assisted non-occlusive anastomosis (SELANA); a feasibility study in a pressurized cadaver model

Objective

To compare intracranial feasibility of the conventional Excimer laser assisted non-occlusive anastomosis (ELANA) with the new experimental sutureless ELANA (SELANA).

Methods

Four pressurized human cadaver heads were bilaterally trepanated, using a combined pterional/pretemporal/transcavernous approach. In each head, seven ELANA anastomoses and seven contralateral SELANA anastomoses were constructed on (1) the proximal PCA/basilar artery (P1 segment/basilar artery; BA), (2) the distal posterior cerebral artery (PCA, P2 segment), (3) the supraclinoidal internal carotid artery (ICA), (4) the ICA bifurcation, (5) the proximal anterior cerebral artery (ACA, A1 segment), (6) the proximal middle cerebral artery (MCA, M1 segment), and (7) the distal MCA (M2 segment).

Results

In total, 26 of 28 ELANA anastomoses (93%) and 22 of 28 SELANA anastomoses (79%) could be completed. Two ELANA anastomoses on the BA could not be finished because of limited space. Six SELANA anastomoses could not be attached because the applicator did not facilitate an angulated anastomosis spot. Of the remaining anastomoses, more ELANA (eight) than SELANA (two) anastomoses could not be realized without manipulation of surrounding structures. The SELANA anastomoses were completed significantly faster than the ELANA, mean difference ranging from 11 min on the M2 to 107 min on the P1/BA.

Conclusion

This comparative study shows potential advantages of the SELANA anastomosis over the ELANA anastomosis because during application, it causes less manipulation of surrounding structures while it is faster and easier. Further preclinical research should be performed in order to improve SELANA feasibility on angulated anastomosis spots and to assess long-term SELANA patency and endothelialization.