Extracranial-intracranial Bypass Research Articles

Endoscopic saphenous vein harvest in neurosurgery: Technical note

BackgroundEndoscopic saphenous vein (SV) graft harvesting was introduced in the neurosurgical field as an attractive alternative to open SV graft harvesting. Methods: The left leg was draped, and the subcutaneous vein was identified by ultrasonography. The vein was harvested with use of the endoscopic Vasoview vessel harvesting system. Results: We performed six endoscopic SV graft harvest procedures for extracranial–intracranial bypass and autologous vein patch angioplasty for carotid artery stenosis. Conclusion: A high-quality graft was harvested with a good cosmetic outcome.

In Reply to the Letter to the Editor Regarding “Efficacy and Safety of Emergency Extracranial-Intracranial Bypass for Revascularization Within 24 Hours on Large Artery Occlusion with Intracranial Stenosis”

In Reply to the Letter to the Editor Regarding “Efficacy and Safety of Emergency Extracranial-Intracranial Bypass for Revascularization Within 24 Hours on Large Artery Occlusion with Intracranial Stenosis”

Letter to the Editor Regarding “Efficacy and Safety of Emergency Extracranial-Intracranial Bypass for Revascularization Within 24 Hours in Resolving Large Artery Occlusion with Intracranial Stenosis”

The current trend toward endovascular treatment of brain aneurysms may have a negative impact on young neurosurgeons who are less exposed to these lesions, thus affecting the acquisition of surgical skills in the field. Different training models have emerged to help cope with this issue, but these have specific pitfalls. Training models based on live animals or cadaveric specimens face increasing restrictions as regulations become a barrier in accessibility for everyday skills development. We introduce a novel, realistic, and inexpensive simulation model using a fresh bovine brain, and we assess its face and content validity as a training tool.A fresh bovine brain is used to simulate microsurgical fissure dissection. Arterial and aneurysmal components are created with arteries and veins harvested from chicken thigh. A 12-item questionnaire using the Likert numeric scale (grades 1 − 5) was used to assess the validity of model in 10 surgeons.Ten neurosurgeons performed the simulated clipping of the aneurysm and completed a questionnaire. All surgeons surveyed responded “agree” or “strongly agree” that the simulator, and the skills trained with it, are comparable to clipping brain aneurysms. All respondents believed that this simulator could improve patient safety.We present a novel, realistic, and inexpensive simulation model for the clipping of brain aneurysms. This model was partially validated by the opinion of field experts. We believe this model has the potential to become a useful training tool for young neurosurgeons who have little exposure to real aneurysm cases.

Extracranial-intracranial bypass in a neonate with multiple ruptured middle cerebral artery aneurysms: illustrative case

BACKGROUNDReports of ruptured neonatal aneurysms are rare in neurosurgical literature. Pediatric aneurysms differ from adult aneurysms, notably in morphology, size, number, and risk of rerupture. Many authors report experience with clipping, citing durability and decreased use of radiation as benefits over endovascular intervention. Few authors report extracranial-to-intracranial bypass because small pediatric vessels make this option challenging. The authors discussed a case of a newborn with multiple ruptured aneurysms, one of the youngest reported cases involving extracranial-intracranial bypass.OBSERVATIONSA 3-week-old baby presented with hemorrhage from multiple complex middle cerebral artery (MCA) aneurysms. Because of young age, endovascular intervention was not possible; therefore, the patient received craniotomy. Upon exploration, clip reconstruction was impossible; the vessel was trapped, and superficial temporal artery (STA)-MCA bypass was performed. The recipient vessel diameter was 0.3 mm. The postoperative course was complicated by seizures as well as symptomatic vasospasm, which was treated with intraarterial verapamil and ventriculostomy. At last follow-up, the patient was developing normally and was ambulatory with minimal deficit.LESSONSThis case, one of the youngest patients reported, highlighted details of pediatric aneurysm management, such as propensity for multiple/fusiform aneurysms and high risk of re-hemorrhage, with significant mortality. The authors recommended aggressive, early intervention in pediatric aneurysms at centers with surgeons familiar with both endovascular intervention and cerebral bypass.

Increased cerebrovascular reactivity in selected brain regions after extracranial-intracranial bypass improves the speed and accuracy of visual cancellation in patients with severe steno-occlusive disease: a preliminary study

The effect of the change in cerebrovascular reactivity (CVR) in each brain area on cognitive function after extracranial-intracranial bypass (EC-IC bypass) was examined. Eighteen patients who underwent EC-IC bypass for severe unilateral steno-occlusive disease were included. Single-photon emission CT (SPECT) for evaluating CVR and the visual cancellation (VC) task were performed before and after surgery. The accuracy of VC was expressed by the arithmetic mean of the age-matched correct answer rate and the accurate answer rate, and the averages of the time (time score) and accuracy (accuracy score) of the four VC subtests were used. The speed of VC tended to be slower, whereas accuracy was maintained before surgery. The EC-IC bypass improved CVR mainly in the cerebral hemisphere on the surgical side. On bivariate analysis, when CVR increased post-operatively, accuracy improved on both surgical sides, but the time score was faster on the left and slower on the right surgical side. Stepwise multiple regression analysis showed that the number of the brain regions associated with the time score was 5 and that associated with the accuracy score was 4. In the hemodynamically ischemic brain, processing speed might be adjusted so that accuracy would be maintained based on the speed-accuracy trade-off mechanism that may become engaged separately in the left and right cerebral hemispheres when performing VC. When considering the treatment for hemodynamic ischemia, the relationship between CVR change and the speed-accuracy trade-off in each brain region should be considered.

Ischemic Stroke Revascularization.

Extracranial-intracranial (EC-IC) bypass is one of the most fundamental techniques for ischemic cerebrovascular disease (CVD). We describe the standard surgical strategies, advanced techniques, and controversies concerning revascularization of ischemic stroke. The standard surgical strategies and techniques emphasize how to determine surgical indication, which should be decided for symptomatic internal carotid artery or middle cerebral artery (MCA) occlusive disease with misery perfusion detected by quantitative single photon emission computed tomography. Advanced techniques are available for complex situations such as posterior circulation revascularization, Bonnet bypass for common carotid artery obstruction, and various EC-IC bypasses for ischemia in the MCA and/or anterior cerebral artery territories using inter-grafts such as femoral veins and radial arteries, illustrated by our surgical results and experiences. Controversies include endovascular treatment complementary to EC-IC bypass. Finally, we advocate emergent EC-IC bypass for progressive ischemic CVD, particularly for contraindication or unsuccessful treatment after intravenous tissue plasminogen activator administration and/or endovascular thrombolysis. EC-IC bypass surgery can be reliable for ischemic CVD under strict optimal surgical indications using safe and reliable surgical techniques.

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

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

Double-barrel STA-MCA bypass and partial trapping of a ruptured mycotic MCA aneurysm with flash fluorescence technique.

Mycotic brain aneurysms are rare and unusual cerebrovascular lesions arising from septic emboli that degrade the elastic lamina and vessel wall of intracranial arteries, which results in pathologic dilatation. Mycotic aneurysms are nonsaccular lesions that are not often suitable for clipping and instead require bypass, trapping, and flow reversal. This case demonstrates the use of indocyanine green “flash fluorescence” to identify the cortical distribution supplied by an aneurysm’s outflow, facilitating safe treatment with a double-barrel extracranial-intracranial bypass and partial trapping and conversion of a deep bypass to a superficial one.The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID21163

Moyamoya disease

Background: Moyamoya disease (MMD) is a rare pathology caused by a progressive unilateral or bilateral stenosis of the terminal portion of the internal carotid artery, leading to the development of collateral vessels. Case Presentation: We report a rare case of a 46-year-old male, born in the city of São Paulo, Brazil, with sudden muscular strength deficit and right hemiparesis, associated with headache and emesis. A priori, the initial diagnosis was arteriovenous malformation (AVM) after performing a series of complementary tests during the patient’s follow-up, also considering the clinical picture similar to that of Moyamoya disease (MMD). The conclusive diagnosis of MMD was finally established when the magnetic resonance imaging (MRI) showed a network of tortuous and dilated collateral vessels, with a hazy “smoke cloud” aspect with stenosis of the M1 segment of the middle cerebral artery (MCA), branch of the artery internal carotid artery (ICA). Conclusion: The recommended treatment was surgical revascularization with extracranial-intracranial bypass, with a favorable prognosis to the patient.

Blood volume flow in the superficial temporal artery assessed by duplex sonography: predicting extracranial-intracranial bypass patency in moyamoya disease.

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery is an important therapy for symptomatic moyamoya disease. Its success depends on bypass function, which may be impaired by primary or secondary bypass insufficiency. Catheter angiography is the current gold standard to assess bypass function, whereas the diagnostic value of ultrasonography (US) has not been systematically analyzed so far. The authors analyzed 50 STA-MCA bypasses in 39 patients (age 45 ± 14 years [mean ± SD]; 26 female, 13 male). Bypass patency was evaluated by catheter angiography, which was performed within 24 hours after US. The collateral circulation through the bypass was classified into 4 types as follows: the bypass supplies more than two-thirds (type A); between one-third and two-thirds (type B); or less than one-third (type C) of the MCA territory; or there is bypass occlusion (type D). The authors assessed the mean blood flow velocity (BFV), the blood volume flow (BVF), and the pulsatility index (PI) in the external carotid artery and STA by duplex sonography. Additionally, they analyzed the flow direction of the MCA by transcranial color-coded sonography. US findings were compared between bypasses with higher (types A and B) and lower (types C and D) capacity. Catheter angiography revealed high STA-MCA bypass capacity in 35 cases (type A: n = 22, type B: n = 13), whereas low bypass capacity was noted in the remaining 15 cases (type C: n = 12, type D: n = 3). The BVF values in the STA were 60 ± 28 ml/min (range 4-121 ml/min) in the former and 12 ± 4 ml/min (range 6-18 ml/min) in the latter group (p < 0.0001). Corresponding values of mean BFV and PI were 57 ± 21 cm/sec (range 16-100 cm/sec) versus 22 ± 8 cm/sec (range 10-38 cm/sec) (p < 0.0001) and 0.8 ± 0.2 (range 0.4-1.3) versus 1.4 ± 0.5 (range 0.5-2.4) (p < 0.0001), respectively. Differences in the external carotid artery were less distinct: BVF 217 ± 71 ml/min (range 110-425 ml/min) versus 151 ± 41 ml/min (range 87-229 ml/min) (p = 0.001); mean BFV 47 ± 17 cm/sec (range 24-108 cm/sec) versus 40 ± 7 cm/sec (range 26-50 cm/sec) (p = 0.15); PI 1.5 ± 0.4 (range 1.0-2.5) versus 1.9 ± 0.4 (range 1.2-2.6) (p = 0.009). A retrograde blood flow in the MCA was found in 14 cases (9 in the M1 and M2 segment; 5 in the M2 segment alone), and all of them showed a good bypass function (type A, n = 10; type B, n = 4). The best parameter (cutoff value) to distinguish bypasses with higher capacity from bypasses with lower capacity was a BVF in the STA ≥ 21 ml/min (sensitivity 100%, negative predictive value 100%, specificity 91%, positive predictive value 83%). Duplex sonography is a suitable diagnostic tool to assess STA-MCA bypass function in moyamoya disease. Hemodynamic monitoring of the STA by US provides an excellent predictor of bypass patency.

Horizontal stent deployment via extracranial-intracranial bypass in coil embolization of basilar apex aneurysms: technical report.

The endovascular treatment of large, wide-necked basilar apex aneurysms (BAAs) remains challenging. Although horizontal stent deployment across both P1 segments of the posterior cerebral arteries (PCAs) would be an optimal strategy in coil embolization of wide-necked BAAs, this is only feasible in cases with anatomically favorable access. In rare circumstances, large-diameter conduits of extracranial-intracranial (EC-IC) bypass can also provide a good access route for endovascular treatment of complex intracranial aneurysms. We describe the technique of accessing the PCA via EC-IC bypass grafts and deploying a stent horizontally across the neck of BAA and its coil embolization. We provide a detailed technical review and describe some pitfalls of the procedure. Two patients underwent EC-IC bypass surgery prior to the treatment of a large, wide-necked BAA. The radial artery and saphenous vein were used as grafts, respectively. To facilitate coil embolization for a large BAA, a PCA-to-PCA horizontal stent was deployed via the bypass graft. Trans-cell and jailing techniques were used, respectively. Both aneurysms were completely occluded, and the patients were discharged without any neurological deficit. Horizontal stent deployment via EC-IC bypass grafts can be performed safely, providing proper closure of the aneurysmal neck and apposition to both PCAs, facilitating complete coil embolization.

Double-barrel STA-MCA bypass for cerebral revascularization: lessons learned from a 10-year experience.

In select patients, extracranial-intracranial (EC-IC) bypass remains an important tool for cerebral revascularization. Traditionally, superficial temporal artery-middle cerebral artery (STA-MCA) bypass was performed using one limb of the STA only. In an attempt to augment flow and to direct flow to different ischemic areas of the brain, the authors adopted a "double-barrel" technique in which both branches of the STA are used to revascularize distinct MCA territories. A series of consecutive double-barrel STA-MCA bypasses performed between 2010 and 2020 were reviewed. Each anastomosis was directed to augment flow to a territory most at risk based on preoperative perfusion studies, cerebral angiography, and intraoperative indocyanine green data. CT perfusion and CTA were routinely used to evaluate postoperative augmentation and graft patency. Patient perioperative outcomes, surgical complications, and modified Rankin Scale (mRS) scores at the last follow-up were reported. Forty-four patients (16 males, 28 females) successfully underwent double-barrel STA-MCA bypass on 54 cerebral hemispheres: 28 operations were for moyamoya disease, 23 for atherosclerotic disease refractory to medical therapy, 2 for complex cerebral aneurysms, and 1 for carotid occlusion as a sequela of cavernous meningioma growth. Ten patients underwent multiple operations, 9 of whom had moyamoya disease/syndrome, with the subsequent operation on the contralateral hemisphere. The average patient age at surgery was 45.1 years (range 14-73 years), with a mean follow-up time of 22.1 months. Intraoperative graft patency was confirmed in 100% of cases, and 101 (98.1%) of the 103 anastomoses with imaging follow-up were patent. Perfusion to the revascularized hemisphere was improved in 88.2% of cases. Perioperative ischemic and hemorrhagic complications occurred in 8 procedures (2 were asymptomatic), whereas remote ischemic and hemorrhagic events occurred in 7 cases. There was no mortality in the series, and the mean patient mRS scores were 1.72 at presentation and 1.15 at the last follow-up. The high rates of intraoperative and postoperative patency support the feasibility of dual-anastomosis STA-MCA bypass for revascularization. The perioperative complication rate is not significantly different from that of single-anastomosis bypass. The functional outcomes at follow-up and perfusion improvement postoperatively support the efficacy and safety of this method as a treatment strategy.

External carotid artery to internal carotid artery transposition to augment flow for a superficial temporal artery to middle cerebral artery bypass associated with severe external carotid artery stenosis.

Donor vessel quality can impact the outcome of extracranial-intracranial (EC-IC) bypass. External carotid artery (ECA) disease may produce embolism into the anastomosis and cerebral territory and possibly reduce flow in the superficial temporal artery (STA). Previously reported remedies to ECA stenosis include ECA endarterectomy, stenting, and angioplasty. Clinical presentation A middle-aged patient with chronic left MCA occlusion, progressive ischemic symptoms on maximal medical therapy, and imaging confirmation of compromised hemodynamic reserve was evaluated for EC-IC bypass. Angiography demonstrated severe ECA origin stenosis. An ECA-ICA transposition was performed, primarily to eliminate the risk of emboli and secondarily to possibly improve the STA flow. The patient sustained an excellent radiological and clinical outcome, and the STA donor cut-flow was increased modestly by 22% (45 to 55mL/min). This case is the first report of an ECA to internal carotid artery transposition as an option in the management of ECA stenosis in preparation for an STA-MCA bypass for the purpose of flow augmentation.

Rescue Strategy for Troublesome Situations Related to Recipient and Donor Arteries During Low-Flow Bypass Surgery

Although technically demanding, bypass surgery is a vital part of the neurosurgical armamentarium. The aim of this article was to present representative troublesome cases related to the manipulation of donor arteries (DAs) and recipient arteries during low-flow extracranial-intracranial bypass. In the past 5 years, 507 low-flow bypass surgeries were performed in patients with cerebral aneurysms, moyamoya disease, and intracranial atherosclerotic stenosis. Frustrating perioperative situations were retrospectively reviewed, and 6 representative cases were described. Case 1 involved repeat microanastomosis owing to occlusion of the anastomotic segment by thrombus formation. Case 2 involved repair of the DA injured by thermal energy. Case 3 involved direct repair of the DA damaged by a sharp knife. Case 4 involved repeat microanastomosis owing to avulsion of the anastomotic segment. Case 5 involved lengthening of the short DA with a nearby interposition graft. Case 6 involved use of retrograde flow via the distal segment of the DA secondary to the injury of the proximal segment of the DA. In all patients, rescue procedures were successful, and bypass flow was patent with no relevant complications. The intraoperative accidents reported here were frustrating; however, all patients were safely rescued without significant sequelae. It is hoped that our experiences will help young neurosurgeons handle troublesome situations.

Evaluation of Revascularization in Different Suzuki Stages of Ischemic Moyamoya Disease by Whole-Brain CT Perfusion.

Objective: This study compared the clinical features and hemodynamic characteristics of patients in different Suzuki stages of ischemic moyamoya disease (iMMD) before and after treatment with extracranial-intracranial (EC-IC) bypass surgery combined with encephalo-duro-myo-synangiosis and whole-brain computed tomography perfusion (WB-CTP).Methods: A total of 126 patients in different Suzuki stages (II, III, IV, and V) of iMMD who underwent bypass surgery from April 2013 to August 2020 were included in this retrospective study. MIStar automatic analysis of Whole brain CT perfusion imaging software (WB-CTP, Apollo Medical Imaging Technology, Melbourne, Australia) was used. The patients also underwent WB-CTP 1 day before and 1 week and 3 months after the surgery. The relationships between hemodynamic parameters in WB-CTP including delay time (DT) > 3 s, relative cerebral blood flow (rCBF) < 30%, mismatch and mismatch ratio, and clinical outcomes were evaluated for different Suzuki stages, with comparisons between early (II and III) and late (IV and V) stages.Results: Combined bypass surgery was performed in 161 hemispheres of 126 patients with iMMD. Brain volume with DT > 3 s was decreased 1 week (51.5 ± 11.8 ml, P < 0.05) and 3 months (41.5 ± 10.7 ml, P < 0.05) after bypass compared to 1 day before bypass (104.7 ± 15.1 ml) in early-stage patients. In late-stage patients, the volume was increased 1 week after bypass compared to the preoperative value (154.3 ± 14.7 vs. 118.3 ± 19.1 ml, P < 0.05). Preoperative brain volume with rCBF < 30% was lower (9.8 ± 3.9 vs. 33.5 ± 11.0 ml) whereas preoperative mismatch ratio was higher (11.2 ± 2.8 vs. 3.6 ± 1.6) in early-stage as compared to late-stage patients (both P < 0.05). A higher modified Rankin scale score (0–1) was achieved by early-stage patients than by those in the late stage (93.8 vs. 80.4%, P < 0.05) at the 3-month follow-up.Conclusions: WB-CTP is useful for assessing the effectiveness of combined bypass/revascularization in different Suzuki stages of iMMD. Patients in the early stage of disease with higher preoperative brain volume with DT > 3 s and mismatch ratio show greater improvements in hemodynamic parameters and fewer postoperative complications associated with hemodynamic disturbance following bypass than patients in the late stage. Preoperative mismatch ratio can serve as a marker for assessing the status of collateral circulation in different Suzuki stages of iMMD.

Intracranial Fusiform and Circumferential Aneurysms of the Main Trunk: Therapeutic Dilemmas and Prospects.

Intracranial fusiform and circumferential aneurysms (IFCAs), especially those located on the main trunk, are uncommon and difficult to manage. Currently, literature focused on IFCAs on the main trunk of cerebral arteries is lacking. The treatment of IFCAs is still under debate. Therefore, in this review, we further explore the treatment of this complicated entity. In addition, we also present some interesting cases. Based on the literature review and our experience, we found that IFCAs are often located in the vertebrobasilar system and that ruptured or large symptomatic IFCAs are associated with increased mortality and higher rebleeding rates. The treatment strategies for IFCAs can be classified as deconstructive and reconstructive methods via open surgery and/or endovascular treatment (EVT). Currently, EVT is a popular method and the main therapeutic choice. In particular, flow diversion has revolutionized the treatment of IFCAs. Parent artery occlusion (PAO) with or without revascularization may still be considered a suitable choice. Complex IFCAs that cannot be resolved by EVT can also be treated via open surgery with or without extracranial–intracranial bypass. Targeted embolization for the weak points of IFCAs is a temporary or palliative choice that is rarely used. In summary, despite complications, both surgical treatment and EVT are effective options for appropriately selected cases. Due to the development of endovascular implants, EVT will have better prospects in the future.

Efficacy and Safety of Emergency Extracranial–Intracranial Bypass for Revascularization within 24 Hours in Resolving Large Artery Occlusion with Intracranial Stenosis

Endovascular treatment (EVT) is less effective for intracranial atherosclerosis-induced emergent large vessel occlusion. Extracranial-intracranial (EC-IC) bypass surgery is a possible treatment option to augment cerebral blood flow in the perfusion defect area. We compared the efficacy and safety of EC-IC bypass surgery with those of EVT and maximal medical treatment for acute ischemic stroke. The data from 39 patients, for whom vessel revascularization had failed despite mechanical thrombectomy, were retrospectively analyzed. Of the 39 patients, 22 had undergone percutaneous transluminal angioplasty or intracranial stenting (PTA/S), 10 had undergone emergency EC-IC bypass surgery within 24 hours of symptom onset, and 7 had received maximal medical treatment (MMT) only. The patency, perfusion status, and postoperative infarct volume were evaluated. The clinical outcomes were assessed at 6 months postoperatively using the modified Rankin scale. The mean reperfusion time was significantly longer for the EC-IC bypass group (14.9 hours) compared with that in the PTA/S group (4.1 hours) and MMT group (7.5 hours; P < 0.05). The postoperative infarct volume on diffusion-weighted magnetic resonance imaging was significantly lower in the emergency EC-IC bypass group (11.3 cm3) than in the MMT group (68.0 cm3) but was not significantly different from that of the PTA/S group (14.0 cm3; P < 0.05). The proportion of patients with a modified Rankin scale score of 0-2 at 6 months after surgery was significantly higher in the EC-IC bypass group (80%) than in the PTA/S (59%) and MMT (14%) groups (P < 0.05). Emergency EC-IC bypass surgery is an effective and safe treatment option for intracranial atherosclerosis-induced acute ischemic stroke for which EVT is inadequate.

Imaging features of internal maxillary artery and extracranial middle meningeal artery and their relationships on head CTA.

The internal maxillary artery and extracranial middle meningeal artery are vitally important. Anatomical studies of the relationship of between them using computed tomography angiography are rare. This study assessed 75 cases involving 150 sides. And the vascular diameters and lengths of the internal maxillary artery and middle meningeal artery were measured using a GE workstation. The distance between the zygomatic arch midpoint and the internal maxillary artery, the angle between the internal maxillary artery and middle meningeal artery were measured, and the middle meningeal artery branch and internal maxillary artery aneurysm were recorded. The internal maxillary artery course classifications were recorded. All of these parameters were statistically analysed. Ages ranged from 18 to 72 (average 40.2) years, and there were 30 women (40%, 30/75) and 45 men (60%, 45/75). Internal maxillary artery length from its origin to middle meningeal artery origin was 1.37 ± 0.59 cm. The extracranial middle meningeal artery length was 1.79 ± 0.48 cm. The vessel diameters of internal maxillary artery origin, middle meningeal artery origin, and middle meningeal artery at the skull base were 2.93 ± 0.52 mm, 1.58 ± 0.43 mm, and 1.33 ± 0.43 mm, respectively. Among the 150 sides of internal maxillary artery course type, there were 138 superficial (92%, 138/150) and 12 (8%, 12/150) deep course cases. The angle between the internal maxillary artery and middle meningeal artery was 116.2 ± 35.76°. The findings of this study elucidate the imaging features of the internal maxillary artery and extracranial middle meningeal artery and their relationships, which are helpful for the extracranial-intracranial bypass and endovascular treatment via the internal maxillary artery and middle meningeal artery.

A Posterior Communicating Segment Aneurysm of the Supraclinoid Internal Carotid Artery Treated with an Extracranial to Intracranial Bypass and Trapping.

Surgical treatment of giant aneurysms often poses significant challenges. Endovascular techniques have evolved exponentially over the last decades, and most of these complex aneurysms can be treated with flow-diverting techniques; however, successful obliteration of all giant aneurysms is not always possible with endovascular flow-diverting techniques. Although the need for microsurgical intervention has undoubtedly diminished, a versatile-thinking surgeon should keep in mind that obliteration of these aneurysms combined with revascularizing the distal circulation via extracranial–intracranial bypass techniques can provide a potentially life-long durable solution. The key to curing these pathologies is to utilize interdisciplinary decision making with a robust knowledge of the pros and cons of different treatment approaches. Herein, we present a case of a giant posterior communicating segment aneurysm of the left supraclinoid internal carotid artery (ICA), which was treated by obliteration ( Fig. 1 ). Extradural anterior clinoidectomy was used to provide exposure of the supraclinoidal ICA proximal to the aneurysm, and revascularization of the distal circulation was achieved with a common carotid artery to M2-superior trunk bypass using a radial artery interposition graft ( Fig. 2 ). The patient was a 62-year-old female who presented with vision loss in her left eye but was otherwise neurologically intact. She had a history of two unsuccessful flow-diverting stent placement attempts 2 months prior to this surgery. Postoperatively, the patient woke up without any deficits, with her left eye vision partially recovered and ultimately returning to normal at 1-year follow-up. Computed tomography (CT) angiography at a 1-year follow-up showed complete obliteration of the aneurysm and successful revascularization of the distal circulation. The link to the video can be found at: https://youtu.be/DsIuIJJj1l4 .

Response To "Hemoglobin Concentration May Influence the Incidence of Postoperative Transient Neurological Events in Patients With Moyamoya After Extracranial-intracranial Arterial Bypass: A Retrospective Single Center Experience".

Response To "Hemoglobin Concentration May Influence the Incidence of Postoperative Transient Neurological Events in Patients With Moyamoya After Extracranial-intracranial Arterial Bypass: A Retrospective Single Center Experience".