Extracranial-to-intracranial Bypass Research Articles

Abstract WP34: Quantitative Radiological Analysis and Clinical Outcomes of Urgent Bypass for Hemodynamic Compromised Patients With Acute Ischemic Stroke

Objective: This study aimed to demonstrate the effectiveness of urgent extracranial-to-intracranial bypass (EIB) in acute ischemic stroke (AIS) through quantitative analysis of computed tomography perfusion (CTP) results using RAPID software. Methods: We retrospectively analyzed 41 patients who underwent urgent EIB for AIS under strict operation criteria. The quantitative data from CTP images were reconstructed to analyze changes in pre- and postoperative perfusion status in terms of objective numerical values using RAPID software. Short- and long-term clinical outcomes, including complications and neurological status, were also analyzed. Results: Postoperatively, the volume of time-to-max (Tmax) >6 s decreased significantly; it continued to improve significantly until 6 months postoperatively (preoperative, 78 ml (median); immediate postoperative, 23 ml; postoperative 6 months, 7 ml; p = .000). Ischemic core-penumbra mismatch volumes were also significantly improved until 6 months postoperatively (preoperative, 72 ml (median); immediate postoperative, 23 ml; postoperative 6 months, 5 ml; p = .000). In addition, the patients’ neurological condition improved significantly ( p <0.001). Only 1 patient (2.3%) showed progression of infarction. Conclusion: Urgent EIB using strict indications can be a feasible treatment for IAT-ineligible patients with AIS due to large vessel occlusion or stenosis.

Alternative Bypass Technique Using Radial Artery Graft between V3 Segment of Vertebral Artery and Middle Cerebral Artery: Technical Note.

There are some cases where a radial artery (RA) graft is needed for a high-flow extracranial to intracranial (EC-IC) bypass as the external carotid artery (ECA) cannot be utilized as a donor artery. In this report, we describe two cases of extracranial vertebral artery (VA) to middle cerebral artery (MCA) high-flow bypass using an RA graft with an artificial vessel as an alternative bypass technique. The patient was placed supine with a head rotation of 80 degrees. After frontotemporal craniotomy, another C: -shaped skin incision was made at the retroauricular region and the V3 portion of the VA was exposed at the suboccipital triangle. Prior to attempting the high-flow bypass, the superficial temporal artery (STA) was anastomosed to the M4 portion of the MCA as an insurance bypass. The RA graft was anastomosed to the V3 portion of the VA that traveled under the periosteum at the supra-auricular region through an artificial vessel. After RA-M2 anastomosis, an alternative EC-IC bypass, the V3-RA-M2 bypass, was achieved. Postoperative angiography demonstrated successful graft patency and no perioperative complications were observed in both cases. In the cases where a high-flow bypass is required, the V3 portion of the VA is a suitable alternative proximal anastomosis site when the ECA is not a candidate donor. Furthermore, an artificial vessel shows satisfactory protection against graft complications.

Cerebral revascularization for complex middle cerebral artery aneurysms: surgical strategies and outcomes in a single center

Cerebral revascularization is the ultimate treatment for a subset of complex middle cerebral artery (MCA) aneurysms. The decision for the revascularization strategy should be made during the treatment process. This study aimed to summarize the revascularization strategies for different types of complex MCA aneurysms and their outcomes. The clinical data of patients with complex MCA aneurysms who underwent cerebral revascularization since 2015 were analyzed retrospectively. The aneurysms were classified according to the location and other main characteristics that affect the selection of surgical modalities. The corresponding surgical modalities and treatment outcomes were summarized. A total of 29 patients with 29 complex MCA aneurysms were treated with cerebral revascularization from 2015 to 2022. Treated aneurysms were located at the prebifurcation segment in 7 patients, bifurcation segment in 12 patients, and postbifurcation segment in 10 patients. Surgical modalities in the prebifurcation segment included four high-flow extracranial-to-intracranial (EC-IC) bypasses with aneurysm trapping or proximal occlusion, two IC-IC bypasses with aneurysm excision, and one combination bypass with aneurysm excision. In the bifurcation segment, surgical modalities included two low-flow EC-IC bypasses with aneurysm excision or trapping, six IC-IC bypasses with aneurysm excision, three combination bypasses with aneurysm excision, and one constructive clipping with IC-IC bypass. In the postbifurcation segment, surgical modalities included nine IC-IC bypasses with aneurysm excision and low-flow EC-IC bypass with aneurysm trapping. The revascularization strategy for prebifurcation aneurysms was determined based on the involvement of lenticulostriate arteries, whereas the strategy for bifurcation aneurysms was determined based on the number of distal bifurcations and the shape of the aneurysm. The location of the aneurysm determined the revascularization strategy for aneurysms in the postbifurcation segments. Angiography demonstrated that aneurysms were completely obliterated in 26 cases and shrank in 3 cases, and all bypasses except one were patent. The mean follow-up period was 47.5months. Three patients developed hemiplegic paralysis, and one developed transient aphasia postoperatively due to cerebral ischemia. No new neurological dysfunction occurred in the other 25 patients with no recurrence or enlargement of aneurysms during the follow-up. Prebifurcation aneurysms involving the lenticulostriate arteries require proximal occlusion with high-flow bypass. Most of the other aneurysms can be safely excised or trapped by appropriate revascularization strategies according to their location and orientation.

Long-term outcomes and quantitative radiologic analysis of extracranial–intracranial bypass for hemodynamically compromised chronic large artery occlusive disease

This study aimed to demonstrate the effectiveness of nonemergent extracranial-to-intracranial bypass (EIB) in symptomatic chronic large artery atherosclerotic stenosis or occlusive disease (LAA) through quantitative analysis of computed tomography perfusion (CTP) parameters using RAPID software. We retrospectively analyzed 86 patients who underwent nonemergent EIB due to symptomatic chronic LAA. CTP data obtained preoperatively, immediately postoperatively (PostOp0), and 6 months postoperatively (PostOp6M) after EIB were quantitatively analyzed through RAPID software, and their association with intraoperative bypass flow (BF) was assessed. The clinical outcomes, including neurologic state, incidence of recurrent infarction and complications, were also analyzed. The time-to-maximum (Tmax) > 8 s, > 6 s and > 4 s volumes decreased significantly at PostOp0 and up through PostOp6M (preoperative, 5, 51, and 223 ml (median), respectively; PostOp0, 0, 20.25, and 143 ml, respectively; PostOp6M, 0, 7.5, and 148.5 ml, respectively; p < 0.001, p < 0.001, and p < 0.001, respectively). The postoperative improvement in the Tmax > 6 s and > 4 s volumes was significantly correlated with the BF at PostOp0 and PostOp6M (PostOp0, r = 0.367 (p = 0.001) and r = 0.275 (p = 0.015), respectively; PostOp6M r = 0.511 (p < 0.001) and r = 0.391 (p = 0.001), respectively). The incidence of recurrent cerebral infarction was 4.7%, and there were no major complications that produced permanent neurological impairment. Nonemergent EIB under strict operation indications can be a feasible treatment for symptomatic, hemodynamically compromised LAA patients.

Understanding how the primary endpoint impacts the interpretation of trial results: The Japanese Adult Moyamoya bypass trial

BackgroundThe meaning of a clinical trial depends to a large extent on the choice of the primary outcome measure, which can be explanatory or pragmatic. MethodsWe review the Japanese Adult Moyamoya (JAM) trial, that compared surgical extracranial to intracranial (EC-IC) bypass and medical management of hemorrhagic moyamoya disease. We also review some principles which guide the selection of the primary trial endpoint. DiscussionThe main component of the primary outcome measure in JAM was rebleeding, a surrogate outcome that allowed investigators to demonstrate that surgical bypass had causal efficacy. However, the number of patients with a poor outcome, defined as those with a modified Rankin score (mRS)>2, would have been a more pragmatic choice. Unfortunately, the trial was too small to show that patients benefited from surgery. ConclusionThe JAM trial showed that EC-IC bypass can decrease rebleeding in moyamoya patients, but whether patients have better outcomes with surgery remains uncertain. Hard pragmatic clinical primary outcome measures are necessary to guide surgical care.

EC-IC Bypass: “Learning Curve” Experiences of Initial 100 Bypasses in Bangladesh

Abstract Objectives Extracranial to intracranial (EC-IC) bypass is an important part of the armamentarium of a neurosurgeon in managing different vascular and neoplastic pathologies. Here, we report our initial experiences of EC-IC bypasses as experiences in the ‘learning curve’, including preparation and training of the surgeon, getting cases, patient selection, imaging, operative skills and microtechniques, complications, follow-up, and outcome. Lessons learned from the ‘learning curve experiences’ can be very useful for young vascular neurosurgeons who are going to start EC-IC bypass or have already started to perform and find themselves in the learning curve. Methods From July 2009 to September 2018, 100 EC-IC bypasses were performed. We looked back to these cases of EC-IC bypass as our initial or ‘learning curve’ experiences. The recorded data of patient management (EC-IC bypass patient) were reviewed retrogradely. Our preparation for EC-IC bypass was described briefly. Case selection, indications, preparation of the patient for operation, techniques and technical experiences, preoperative difficulties and challenges, postoperative follow-up, complications, patency status of the bypass, and ultimate results were reviewed and studied. Result A total of 100 bypasses were performed in 83 patients, of which 43 were male and 40 were female. The age range was from 04 to 72 years old (average 32 years old). Eleven patients were lost to follow-up postoperatively after 3 months and they were not even available for telephone follow-up. The follow-up period ranged from 3 to 120 months (average of18.4 months). Eight bypasses were high flow bypasses, whereas the number of low flow STA-MCA bypasses was 92. Indication of bypass were (in 83 cases):1. Arterial stenosis/occlusion/dissection causing cerebral ischemia (middle cerebral artery [MCA] stenosis/occlusion-05, MCA dissection-04, internal carotid artery [ICA] occlusion-19); 2. Intracranial aneurysm-30; 3. Moya-Moya disease-21; and 4. Direct carotid cavernous fistula [CCF]-04. Common clinical presentation was hemiparesis &amp; dysphasia in ischemic group with history of transient ischemic attack (H/O TIA) (including Moya Moya disease). Features of subarachnoid hemorrhage (SAH) were the presenting symptoms in intracranial aneurysm group. The average ischemic time, due to clamping of recipient artery, was 28 minutes (range: 20–60 minutes). There was no clamp-related infarction. Two anastomoses were found thrombosed intraoperatively.One preoperatively ambulant patient deteriorated neurologically in the postoperative period. She developed hemiplegia but improved later. Here, the cause seemed to be hyperperfusion. Headache resolved in all cases. TIA and seizures were also gone postoperatively. Ophthalmoplegia recovered in all cases in which it was present, except in one CCF, in which abducent nerve palsy persisted. Complete unilateral total blindness developed in one patient postoperatively (due to ophthalmic artery occlusion), where high flow bypass with ICA occlusion were performed. Red eye and proptosis were cured in CCF cases. Motor and sensory dysphasia improved in all cases in which it was present, except for one case in which preoperative global aphasia converted to sensory aphasia in the postoperative period. Three patients died in the postoperative period. The rest of the patients improved postoperatively. All patients were ambulant with static neurostatus and without new stroke/TIA until the last follow-up. All bypasses were patent until the last follow-up. Conclusion The initial experiences of 100 cases of EC-IC bypass revealed even in inexperienced hand mortality and morbidity in properly indicated cases were low and result were impressive according to the pathological group and aim of bypass. Lessons learned from these experiences can be very helpful for new and beginner bypass neurosurgeons

Extracranial-to-Intracranial Bypass for Distal Internal Carotid Artery and/or Proximal Middle Cerebral Artery Steno-Occlusive Disease: A Case Series of Clinical Outcomes at a Single, High-Volume Cerebrovascular Center.

Extracranial-to-intracranial (EC-IC) bypass was first described by Yasargil in the 1960s for treatment of symptomatic distal internal carotid artery (ICA) and/or proximal middle cerebral artery (MCA) steno-occlusive disease through direct anastomosis. Subsequent bypass trials failed to demonstrate benefit for overall outcomes and stroke rates compared with best medical therapy. However, the procedure remained in the neurosurgeon's armament, with studies showing benefits in select patient populations. With advancements in technology, patient selection has become more comprehensive. To provide a contemporary evaluation of EC-IC bypass from our high-volume cerebrovascular center, focusing on associated clinical outcomes. Consecutive patients who underwent direct EC-IC bypass surgeries for symptomatic distal ICA and/or proximal MCA steno-occlusive disease between April 2015 and September 2019 were identified retrospectively. Medical records were reviewed to collect demographics, clinical presentation, computed tomography perfusion imaging findings, transcranial Doppler results, procedure indication, donor vessel types, anastomosis site, bypass patency, periprocedural complications, postprocedural complications, symptom recrudescence, repeat or new interventions, subjective improvements, and modified Rankin Scale scores. We identified 27 patients who underwent 32 EC-IC bypass procedures. The rate of ipsilateral stroke was 9.4%, with a median follow-up of 8 months (IQR, 4-13 months). Patients experienced a 22.3% improvement in modified Rankin Scale scores, and 70.3% of patients reported subjective improvement and satisfaction at follow-up. Direct EC-IC bypass remains a viable option for revascularization in symptomatic patients with distal ICA and/or proximal MCA steno-occlusive disease.

Quantitative radiological analysis and clinical outcomes of urgent EC-IC bypass for hemodynamic compromised patients with acute ischemic stroke

This study aimed to demonstrate the effectiveness of urgent extracranial-to-intracranial bypass (EIB) in acute ischemic stroke (AIS) through quantitative analysis of computed tomography perfusion (CTP) results using RAPID software. We retrospectively analyzed 41 patients who underwent urgent EIB for AIS under strict operation criteria. The quantitative data from CTP images were reconstructed to analyze changes in pre- and postoperative perfusion status in terms of objective numerical values using RAPID software. Short- and long-term clinical outcomes, including complications and neurological status, were also analyzed. Postoperatively, the volume of time-to-max (Tmax) > 6 s decreased significantly; it continued to improve significantly until 6 months postoperatively (preoperative, 78 ml (median); immediate postoperative, 23 ml; postoperative 6 months, 7 ml; p = 0.000). Ischemic core-penumbra mismatch volumes were also significantly improved until 6 months postoperatively (preoperative, 72 ml (median); immediate postoperative, 23 ml; postoperative 6 months, 5 ml; p = 0.000). In addition, the patients’ neurological condition improved significantly (p < 0.001). Only one patient (2.3%) showed progression of infarction. Urgent EIB using strict indications can be a feasible treatment for IAT-ineligible patients with AIS due to large vessel occlusion or stenosis.

Cerebral Bypass Using the Descending Branch of the Lateral Circumflex Femoral Artery: A Case Series.

When performing extracranial to intracranial (EC-IC) and intracranial to intracranial (IC-IC) bypass, the choice of donor vessel and interposition graft depends on several factors: vessel size and accessibility, desired blood flow augmentation, revascularization site anatomy, and pathology. The descending branch of the lateral circumflex femoral artery (DLCFA) is an attractive conduit for cerebrovascular bypass. To present our institutional experience using DLCFA grafts for cerebral revascularization. Retrospective review of perioperative data and outcomes for patients undergoing cerebrovascular bypass surgery using a DLCFA graft from 2016 to 2019. Twenty consecutive patients underwent EC-IC bypass using a DLCFA interposition graft. Bypass indications included 13 (65%) intracranial aneurysms, 4 (20%) medically refractory atherosclerotic large artery occlusions (internal carotid artery or middle cerebral artery), 2 (10%) internal carotid artery dissections, and 1 (5%) patient with moyamoya disease. Most commonly, a donor superior temporal artery was bypassed to a recipient middle cerebral artery (14 of 20; 70%). Two cases demonstrated graft spasm. Graft occlusion occurred in one patient and was asymptomatic. Perioperative bypass surgery-related ischemia occurred in 3 patients: 1 patient with insufficient bypass flow, 1 patient with graft stenosis because of an adventitial band, and 1 patient with focal status epilepticus in the bypassed territory resulting in cortical ischemia. One donor site hematoma occurred. The median (range) modified Rankin scale (mRS) score on follow-up was 1.5 (1-4) at 7.8 (1-27) months, with most patients achieving good functional outcomes (mRS ≤2). The DLCFA is a versatile graft for cerebral revascularization surgery, demonstrating good outcomes with minimal graft harvest site morbidity and an acceptable graft patency rate.

Maximal Resection of Tumors Encasing the Internal Carotid Artery and Hindering Internal Carotid Artery Expansion Followed by Revascularization Surgery: A Series of Nine Cases at a Single Tertiary Center.

PurposeCerebral reconstruction appears to play a diminished role in managing complex skull base tumors involving vital neurovascular structures.Materials and MethodsPatients with recurrent or progressive middle cranial fossa tumors treated by radical resection followed by extracranial-to-intracranial (EC-IC) bypass from 2014 to 2019 were included. Balloon test occlusion (BTO) was performed preoperatively.ResultsOverall, 9 patients (5 males, 4 females; mean age, 29.9 years) were enrolled. The lesions arose from the parasellar region (3), cavernous sinus (3), petroclival region (2), or orbital apex (1), and all encased the cavernous/petrous portion of the internal carotid artery. Before tumor resection, internal maxillary artery (IMA) bypass was performed for 7 patients, cervical EC-IC bypass was performed for 1 patient, and interposed superficial temporal artery (STA) bypass was performed for 1 patient. BTO failed in 8 patients and was tolerated by one patient. Intraoperative blood flow of the interposed graft was 79.7 ± 37.86 ml/min after IMA bypass, 190.6 ml/min following cervical EC-IC bypass and 75 ml/min after interposed STA bypass. All bypasses were patent on intraoperative indocyanine green angiography. Radical tumor resection was achieved in 5 patients (55.6%), and patency was confirmed postoperatively in 88.8% (8/9) of bypasses. Six patients showed favorable outcomes at discharge. At the 2-year follow-up, 7 patients (77.8%) had favorable outcomes (Karnofsky Performance Scale score>80). At the 1.5-year follow-up, one patient had died due to infarction; at the 3-year follow-up, another patient had developed tumor recurrence despite being asymptomatic.ConclusionCerebral bypass remains a vital tool for managing select middle cranial fossa tumors that invade or erode the surrounding neurovasculature or hinder carotid artery expansion and are difficult to resect.

Factors Influencing Long-Term Blood Flow in Extracranial-to-Intracranial Bypass for Symptomatic Internal Carotid Artery Occlusive Disease: A Quantitative Study.

Maintaining the patency of extracranial-to-intracranial (EC-IC) bypass is critical for long-term stroke prevention. However, reports on the factors influencing long-term bypass patency and quantitative assessments of bypass patency are limited. To quantitatively evaluate blood flow in EC-IC bypass using four-dimensional (4D) flow magnetic resonance imaging (MRI) and investigate factors influencing the long-term patency of EC-IC bypass. Thirty-six adult Japanese patients who underwent EC-IC bypass for symptomatic internal carotid or middle cerebral artery occlusive disease were included. We examined the relationships between decreased superficial temporal artery (STA) blood flow volume and perioperative complications, long-term ischemic complications, patient background, and postoperative antithrombotic medications in patients for whom STA flow could be quantitatively assessed for at least 5 months using 4D flow MRI. The mean follow-up time was 54.7 ± 6.1 months. One patient presented with a stroke during the acute postoperative period that affected postoperative outcomes. No recurrent strokes were recorded during long-term follow-up. Two patients died of malignant disease. Seven cases of reduced flow occurred in the STA, which were correlated with single bypass (P = .0294) and nonuse of cilostazol (P = .0294). STA occlusion was observed in 1 patient during the follow-up period. Hypertension, age, smoking, dyslipidemia, and diabetes mellitus were not correlated with reduced blood flow in the STA. Double anastomoses and cilostazol resulted in long-term STA blood flow preservation. No recurrence of cerebral infarction was noted in either STA hypoperfusion or occlusion cases.

Controversies and Advances in Adult Intracranial Bypass Surgery in 2020

Cerebral revascularization utilizing a variety of bypass techniques can provide either flow augmentation or flow replacement in the treatment of a range of intracranial pathologies, including moyamoya disease, intracranial atherosclerotic disease, and complex aneurysms that are not amenable to endovascular or simple surgical techniques. Though once routine, the publication of high-quality prospective evidence, along with the development of flow-diverting stents, has limited the indications for extracranial-to-intracranial (EC-IC) bypass. Nevertheless, advances in imaging, assessment of cerebral hemodynamics, and surgical technique have changed the risk-benefit calculus for EC-IC bypass. New variations of revascularization surgery involving multiple anastomoses, flow preserving solutions, IC-IC constructs, and posterior circulation bypasses have been pioneered for otherwise difficult to treat pathology including giant aneurysms, dolichoectasia, and medically refractory intracranial atherosclerosis. This review provides a practical update on recent advances in adult intracranial bypass surgery.

Comparative Assessment of Extracranial-to-Intracranial and Intracranial-to-Intracranial In Situ Bypass for Complex Intracranial Aneurysm Treatment Based on Rupture Status: A Case Series

Comparative outcomes of extracranial-to-intracranial (EC-IC) and intracranial-to-intracranial (IC-IC) bypass for complex aneurysm treatment based on rupture status are not well described in the literature. In this study, we compare outcomes of EC-IC and IC-IC bypass for complex intracranial aneurysm treatment based on rupture status. A prospective neurosurgical patient database was retrospectively reviewed. Sixty-three consecutive patients with aneurysm managed with revascularization were identified between July 2014 and December2018. During the study period, 41 patients with aneurysm underwent EC-IC bypass (65%; 24 [58.5%] ruptured, 17 [41.5%] unruptured) and 22 patients with aneurysm underwent IC-IC bypass (34.9%; 13 [59.1%] ruptured, 9 [40.9%] unruptured). Graft spasm occurred in 4 patients (9.8%) in the EC-IC group (all ruptured aneurysms) and all anastomoses were patent on immediate postoperative imaging. Perioperative mortality occurred in 5 patients who underwent EC-IC bypass (12.2%; 3 ruptured, 2 unruptured) EC-IC and 2 patients who underwent IC-IC bypass (9.1%; both ruptured); (P= 0.709). Bypass-related complications occurred only in patients with ruptured aneurysm (2 [8.3%] in the EC-IC group and 0 [0%] in the IC-IC group; P= 0.285). For unruptured aneurysms, the overall complication rate was lower in IC-IC compared with the EC-IC group (P= 0.006). Modified Rankin Scale scores on discharge were significantly lower in IC-IC compared with EC-IC bypass for unruptured aneurysms (P= 0.008). There was a trend for shorter temporary occlusion and hospitalization times and overall better outcomes with IC-IC compared with EC-IC bypass. Although often considered riskier than EC-IC bypass, IC-IC in situ bypass showd a favorable technical and safety profile for the treatment of complex, unruptured aneurysms.

The Effect of Extracranial-to-Intracranial Bypass on Cerebral Vasoreactivity: A 4D Flow MRI Pilot Study.

Extracranial-to-intracranial (EC-IC) surgical bypass improves cerebral blood flow (CBF) and cerebrovascular vasoreactivity (CVR) for patients with carotid occlusion. Bypass graft patency and contribution of the graft to the postoperative increase in CVR are challenging to assess. To assess the effectiveness of 4D flow magnetic resonance imaging (MRI) to evaluate bypass graft patency and flow augmentation through the superficial temporal artery (STA) before and after EC-IC bypass. Three consecutive patients undergoing EC-IC bypass for carotid occlusion were evaluated pre- and postoperatively using CVR testing with pre- and poststimulus 4D flow-MRI for assessment of the bypass graft and intracranial vasculature. Preoperatively, 2 patients (patients 1 and 3) did not augment flow through either native STA. The third, who had evidence of extensive native EC-IC collateralization on digital subtraction angiography (DSA), did augment flow through the STA preoperatively (CVR = 1). Postoperatively, all patients demonstrated CVR > 1 on the side of bypass. The patient who had CVR > 1 preoperatively demonstrated the greatest increase in resting postoperative graft flow (from 40 to 130 mL/minute), but the smallest CVR, with a poststimulus graft flow of 160 mL/minute (CVR = 1.2). The 2 patients who did not demonstrate augmentation of graft flow preoperatively augmented postoperatively from 10 to 20 mL/minute (CVR = 2.0) and 10-80 mL/minute (CVR = 8.0), respectively. Intracranial flow was simultaneously interrogated. Two patients demonstrated mild reductions in resting flow velocities in all interrogated vessels immediately following bypass. The patient who underwent CVR testing on postoperative day 48 demonstrated a stable or increased flow rate in most intracranial vessels. Four-dimensional flow MRI allows for noninvasive, simultaneous interrogation of the intra- and extracranial arterial vasculature during CVR testing, and reveals unique paradigms in cerebrovascular physiology. Observing these flow patterns may aid in improved patient selection and more detailed postoperative evaluation for patients undergoing EC-IC bypass.

Safety, Feasibility, and Patient-Rated Outcome of Sonolucent Cranioplasty in Extracranial-Intracranial Bypass Surgery to Allow for Transcranioplasty Ultrasound Assessment

ObjectiveWe sought to analyze the safety and feasibility of elective sonolucent cranioplasty in the setting of extracranial-to-intracranial (EC-IC) bypass surgery to monitor bypass patency using ultrasound.MethodsPatients who underwent direct EC-IC bypass surgery agreed to sonolucent cranioplasty at the time of surgery and received a sonolucent polymethyl methacrylate (PMMA) implant. Besides monitoring clinical outcome, all patients received transcranioplasty ultrasound (TCUS) on postoperative day 1 and at last follow-up. In addition, bypass patency was confirmed using catheter angiogram and fit of implant using computed tomography. Patient-rated outcome was assessed through phone questionnaire.ResultsEC-IC bypass surgery with PMMA cranioplasty was successful in all 7 patients with patent bypasses on postoperative angiogram. Direct TCUS was feasible in all patients, and bypass patency was monitored. There were no complications such as postoperative hemorrhagic/ischemic complications related to the bypass procedure in this patient population, as well as no complications related to the PMMA implant. Postoperative computed tomography showed favorable cosmetic results of the PMMA implant in both the pterional area for superficial temporal artery−middle cerebral artery bypasses and parietooccipital area for occipital artery−middle cerebral artery bypasses as confirmed by high-rated overall patient satisfaction with favorable cosmetic, pain, and sensory patient-rated outcomes.ConclusionsIn this study we were able to show that this novel technique is safe, allows for patency assessment of the EC-IC bypass using bedside TCUS technique, and is cosmetically satisfying for patients.

Predictive factors for acute thrombogenesis occurring immediately after bypass procedure for moyamoya disease.

Extracranial-to-intracranial (EC-IC) bypass surgery is an effective treatment for patients with moyamoya disease and other conditions. Some patients with moyamoya disease have a risk of acute thrombogenesis at the anastomotic site just after bypass surgery. The purpose of this study was to study risk factors of acute thrombogenesis and determine effective countermeasures. This study included 48 patients (66 EC-IC bypass procedures) with moyamoya disease and 52 controls (54 procedures) without moyamoya disease. The development of acute thrombogenesis was compared between the moyamoya disease and control groups. In the moyamoya disease group, clinical and radiological characteristics were assessed with respect to acute thrombogenesis. In the patients with acute thrombogenesis, causes of technical problems were retrospectively examined. The incidence of acute thrombogenesis was significantly higher in the moyamoya disease group than those in the control group. In the moyamoya disease group, acute thrombogenesis was observed in seven patients. In the moyamoya disease group, the magnetic resonance angiography (MRA) scores were significantly higher in patients with acute thrombogenesis than those in the patients without acute thrombogenesis. In the multivariate analysis, the predictive factor of acute thrombogenesis in moyamoya disease was a high MRA score (odds ratio, 2.336; p = 0.009). During EC-IC bypass surgery for moyamoya disease, acute thrombogenesis should be considered to obtain a high patency rate, particularly in patients with high MRA scores. Acute thrombogenesis will not influence morbidity if proper countermeasures are followed; therefore, the prediction and recognition of white thrombus are important for a successful bypass surgery.

Practice Trends in Intracranial Bypass Surgery in a 21-Year Experience

The aim of this study was to analyze practice trends in specific intracranial bypass types in a large, consecutive bypass experience. This retrospective review of a prospectively maintained database included all intracranial bypasses performed by a single surgeon over 21 years. Bypass types were grouped into 7 categories and analyzed in seven 3-year time intervals: type 1= extracranial-to-intracranial (EC-IC) bypass with scalp arteries as donors; type 2= EC-IC bypass with interposition graft to cervical carotid arteries; type 3= arterial reimplantation; type 4= in situ bypass; type 5= reanastomosis; type 6= intracranial-to-intracranial bypass with interposition graft; and type 7= combination bypass. In total, 598 intracranial bypasses were performed including 359 type 1, 59 type 2, 24 type 3, 30 type 4, 37 type 5, 36 type 6, and 53 type 7. Although type 1 and type 3-7 bypasses increased, type 2 bypasses decrease in frequency. Aneurysms were the most common bypass indication (41.8%), followed by moyamoya disease (31.8%), and intracranial arterial stenosis or occlusion (24.9%). Endovascular treatment failure was observed in 10.8% of the aneurysm patients treated with a bypass procedure. Intracranial bypass remains an essential technique for open vascular neurosurgeons. The classic low-flow EC-IC bypasses, intracranial-to-intracranial, and combination bypasses increased over time, whereas the high-flow EC-IC interpositional bypasses decreased over time. These trends reflect the increasing use of flow diverters as well as the need for surgical revascularization for complex aneurysms, and those that failed previous endovascular therapy.

Extracranial-Intracranial Bypass for Treatment of Blister Aneurysms: Efficacy and Analysis of Complications Compared with Alternative Treatment Strategies

Blister aneurysms (BAs) represent a clinical challenge without a consensus treatment strategy. We report our institution's experience with BAs with an emphasis on the use of extracranial-to-intracranial (EC-IC) bypass. Seventeen patients with BAs (88% [15/17] ruptured) were treated with microsurgical techniques (5 clip wrappings, 4 clip ligations, 4 EC-IC bypasses and clip trappings, 2 internal carotid artery ligations [1 combined with clip wrapping], and 2 clip trappings). Six of 17 patients experienced intraoperative ruptures. There were no intraoperative ruptures among the bypass cases and 75% (3/4) of patients achieved a good neurologic outcome. Further, a literature review was performed to identify all previously reported cases of BAs undergoing clip ligation, clip wrapping, EC-IC bypass/clip trapping, and endovascular therapies, encompassing 246 BA cases across 33 studies. Intraoperative ruptures occurred in 29% of clip ligations (23/79), 27.2% of clip wrappings (6/35), 16.1% of EC-IC bypasses (5/31), and 0% of endovascular treatments. Aneurysm recurrence occurred in 2.97% (3/101) with endovascular therapies to 0% with EC-IC bypass. Mortality was 8.8% for clip ligation/wrapping (10/114), 6.5% for EC-IC bypass (2/31), and 4.0% for endovascular treatments (4/101). Endovascular interventions have a favorable procedural safety profile but high rates of retreatment for persistent filling or posttreatment aneurysmal growth. Clip ligation and clip wrapping techniques have lower retreatment rates but slightly higher intraoperative risk. EC-IC bypass can safely provide definitive aneurysm securement and should be considered as a first-line therapy for BAs at high-volume bypass centers.

Interdisciplinary Prevention and Management of Wound-Related Complications in Extracranial-to-Intracranial Bypass Surgery

Extracranial-to-intracranial (EC-IC) bypass surgery may be necessary in patients with moyamoya disease and other ischemic conditions. However, there is a potential risk of wound-related complications in some cases. In this study, we report our approach to the prevention of wound-related complications in EC-IC bypass. Technical considerations and pitfalls of surgery are also discussed. This study included 89 patients with ischemic-onset moyamoya disease and atherosclerotic disease who underwent 108 superficial temporal artery (STA)-to-middle cerebral artery bypass procedures. Our study emphasized 3 major features. First, 3-dimensional simulation imaging was used to confirm STA anatomy. Second, the STA was meticulously dissected on the epigaleal layer to protect the galeal layer. Third, scalp skin ischemia was taken into consideration at each step until skin closure. There was no neurologic morbidity or mortality in this series. There were 2 cases of major wound-related complications requiring plastic surgical intervention, and 4 cases of minor complications that were treated conservatively. In major complication cases, the scalp defect was treated with pedicle flap reconstruction. In EC-IC bypass surgery, interdisciplinary management involving neurosurgery, plastic surgery, and radiology should reduce wound-related complications and achieve safe surgery.

Direct Cerebral Revascularization: Extracranial-intracranial Bypass.

In 1967, the first extracranial to intracranial (EC-IC) arterial anastomosis was performed. Since that time, EC-IC bypass surgery has become a widely accepted surgical treatment for patients with IC stenotic or occlusive atherosclerotic lesions. This article will discuss the history, indications, types, surgical methods, and complications of the EC-IC bypass.