Cerebrovascular Bypass Research Articles

Surgical Treatment Strategies for Residual or Recurrent Intracranial Aneurysms Following Endovascular Embolization.

To explore how to effectively manage the residual or recurrent intracranial aneurysms after embolization. The authors retrospectively reviewed our experience of endovascular interventional therapy, surgical clipping, and cerebrovascular bypass surgery in the treatment of residual or recurrent aneurysms after embolization at the authors' institution from 2018 to 2022. The Glasgow Outcome Scale of 28 patients after the procedure and at discharge showed that 24 recovered well, 3 had severe disability, and 1 died. During the 24-month follow-up, 26 had a good recovery, 1 suffered from disability, and 1 died. Two cases of aneurysm recurrence were detected, and both were treated through endovascular therapy. Among them, 1 case underwent a repeat endovascular embolization, and 1 case was switched to surgical clipping. No residual aneurysms were observed in the remaining patients who underwent bypass surgery, and their bypass grafts were all patent. Based on the clinical status of patients, aneurysmal characteristics, surgical risk, and possibility of rerupture of aneurysms, an individualized strategy was proposed for residual or recurrent aneurysms after embolization. The use of endovascular interventional therapy or surgical clipping can be safely and effectively managed, and cerebrovascular bypass surgery can effectively manage complex aneurysms.

Superficial Temporal Artery to Superior Cerebellar Artery STA (E-S*) s2 Bypass for Dolichoectatic Superior Cerebellar Artery Aneurysm After Failed Flow Diversion: 2-Dimensional Operative Video.

Flow diversion is a unique interventional tool with evolving roles in the treatment of intracranial aneurysms.1 Although flow diversion strategies can be highly effective in appropriately selected patients, their off-label use is controversial. As flow diversion indications have expanded, so has the incidence of treatment failure, resulting in an evolving subgroup of patients with atypical lesions that require complex salvage strategies, such as cerebrovascular bypass.2,3 We report a residual dolichoectatic superior cerebellar artery aneurysm in which flow diversion failed, which was treated through superficial temporal artery to superior cerebellar artery bypass.4,5 Being a single case report, institutional review board approval was not needed. Patient consent was obtained. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Learning Curve of Robotic End-to-Side Microanastomoses.

Robotics are becoming increasingly widespread within various neurosurgical subspecialties, but data pertaining to their feasibility in vascular neurosurgery are limited. We present our novel attempt to evaluate the learning curve of a robotic platform for microvascular anastomoses. One hundred and sixty one sutures were performed and assessed. Fourteen anastomoses (10 robotic [MUSA-2 Microsurgical system; Microsure] and 4 hand-sewn) were performed by the senior author on 1.5-mm caliber tubes and recorded with the Kinevo 900 (Zeiss) operative microscope. We separately compared interrupted sutures (from needle insertion until third knot) and running sutures (from needle insertion until loop pull-down). Average suture timing across all groups was compared using an unpaired Student's t test. Exponential smoothing (α = 0.2) was then applied to the robotic data sets for validation and a second set of t tests were performed. We compared 107 robotic sutures with 54 hand-sewn sutures. There was a significant difference between the average time/stitch for the robotic running sutures (n = 55) and the hand-sewn running sutures (n = 31) (31.2 seconds vs 48.3 seconds, respectively; P-value = .00052). Exponential smoothing (α = 0.2) reinforced these results (37.6 seconds vs 48.3 seconds; P-value = .014625). Average robotic running times surpassed hand-sewn by the second anastomosis (38.8 seconds vs 48.3 seconds) and continued to steadily decrease with subsequent stitches. The average of the robotic interrupted sutures (n = 52) was significantly longer than the hand-sewn (n = 23) (171.3 seconds vs 70 seconds; P = .000024). Exponential smoothing (α = 0.2) yielded similar results (196.7 seconds vs 70 seconds; P = .00001). However, average robotic interrupted times significantly decreased from the first to the final anastomosis (286 seconds vs 105.2 seconds; P = .003674). Our results indicate the learning curve for robotic microanastomoses is short and encouraging. The use of robotics warrants further study for potential use in cerebrovascular bypass procedures.

217 Early Experience With Robotic Microvascular Anastomoses

INTRODUCTION: Robotics are becoming increasingly widespread within various neurosurgical subspecialties. The adoption of robotic technology within vascular neurosurgery is of great interest, but data pertaining to its feasibility is currently limited. METHODS: 68 sutures were performed and assessed. 6 anastomoses (3 robotic and 3 hand-sewn) were performed on 1-1.5 mm caliber tubes and recorded with the operative microscope. We separately compared interrupted sutures (from needle insertion until third knot) and running sutures (from needle insertion until stitch pull-out). Average suture timing across all groups was compared using an unpaired student’s T test. RESULTS: We compared 29 robotic sutures to 39 hand-sewn sutures. There was no significant difference between the average time/stitch for the robotic running sutures (n = 18) and the hand-sewn running sutures (n = 16) (45.6 s vs. 41.2 s; p-value = 0.3). The average for the first robotic anastomosis (n=7) was significantly longer than the second (n = 11) (56.3 vs. 38.3; p = .03). The first robotic anastomosis had a negative slope (-8.5). Interestingly, both the second robotic end-to-side anastomosis and the hand-sewn control had shallow positive slopes (1.5 and 2.6). The average of the robotic interrupted sutures (n = 11) was significantly longer than the hand-sewn (n = 23) (286 s vs. 70; p<.01). The average time for the first robotic interrupted anastomosis (n = 7) was significantly longer than the second (n = 4) (366.9 s vs. 144.5; p=0.008). CONCLUSIONS: Our results indicate that the learning curve for suturing robotic microanastomoses is short and encouraging. Similar performance to hand-sewn running sutures is possible robotically with minimal practice. Although the learning curve for the interrupted group was encouraging, we only reached similar results to hand-sewn in the very last robotic sutures. Overall, the use of robotics warrants further study for potential use in cerebrovascular bypass procedures.

Posterior Cerebral Artery–to–Superior Cerebellar Artery Side-to-Side Bypass via Extreme Lateral Supracerebellar Infratentorial Approach: Technical Note

Background and objectiveDifficult-to-treat aneurysms of the distal posterior cerebral artery (PCA) can often be treated by parent artery occlusion. A cerebrovascular bypass can complement PCA occlusion to curb the risk of ischemic complications.An in-situ bypass may be considered when the occipital artery or superficial temporal artery cannot serve as a bypass donor.This paper describes the use of a side-to-side bypass of superior cerebellar artery (SCA) as a donor to the posterior cerebral artery (PCA) via an extreme lateral supracerebellar infratentorial (ELSCIT) approach. This bypass approach can be a useful surgical strategy for PCA revascularization. MethodsA 40-year-old female patient underwent a side-to-side PCA-SCA bypass via the ELSCIT approach for the treatment of a complex and previously coiled PCA aneurysm.Bypass was followed by endovascular aneurysm and parent artery occlusion. ResultsPostoperatively, the patient experienced transient, partial trochlear nerve palsy of the left eye without ischemic lesions on MRI. The clinical condition was stable and angiography showed a patent bypass and complete aneurysm occlusion 12 months after surgery. ConclusionThe ELSCIT-approach offers access to the medial and distal PCA that is well suitable for a side-to-side PCA-SCA bypass. This type of approach and bypass may be of value when revascularization of a P2-P3 portion of the PCA is needed, but a suitable occipital artery (OA) or superficial temporal artery (STA) is not available.

Intraoperative contrast-enhanced ultrasound evaluates the hemodynamic change of cerebral revascularization in adult moyamoya disease: Preliminary results

PurposeThis study aimed to determine the feasibility of using intraoperative contrast-enhanced ultrasound (CEUS) to assess subcortical hemodynamic changes in moyamoya disease patients who had undergone combined revascularization. It also aimed to investigate the correlation between quantitative CEUS parameters and post-operative neural functional recovery. MethodsThis study included seventeen patients diagnosed with moyamoya disease, confirmed through cerebral angiography, who underwent combined revascularization. Intraoperative subcortical hemodynamics were assessed using CEUS before and immediately after cerebrovascular bypass. Hemodynamic parameters were calculated by analyzing the time-intensity curve generated from a defined region of interest in each CEUS video. Post-operative neurological symptoms, computed tomography records, and short-term modified Rankin Scale (mRS) scores were also recorded. ResultsDuring the post-operative follow-up, 29.4 % of the patients experienced new neurological symptoms, including epilepsy, dyskinesia, and language impairment. Overall, CEUS quantitative parameters suggested that blood supply improved after surgery. And certain hemodynamic parameters exhibited a stronger correlation with the mRS scores, with correlation coefficients ranging up to 0.73 (p < 0.01). However, no statistically significant differences were observed among the different functional groups. The advanced parameter of wash-out intensity (δ WOI), which signifies the rate of change at the point when blood flow is completely washed out, demonstrated a significant difference between two functional groups (p = 0.02) and exhibited a correlation with mRS scores (correlation coefficients: 0.55, p = 0.02). ConclusionsThis preliminary study suggests that quantitative intraoperative CEUS can measure subcortical hemodynamic changes. It provides a novel non-invasive method that may predict the short-term post-operative neural functional recovery of combined revascularization in moyamoya disease patients.

Seven bypasses simulation set: description and validity assessment of novel models for microneurosurgical training.

Microsurgical training remains indispensable to master cerebrovascular bypass procedures, but simulation models for training that accurately replicate microanastomosis in narrow, deep-operating corridors are lacking. Seven simulation bypass scenarios were developed that included head models in various surgical positions with premade approaches, simulating the restrictions of the surgical corridors and hand positions for microvascular bypass training. This study describes these models and assesses their validity. Simulation models were created using 3D printing of the skull with a designed craniotomy. Brain and external soft tissues were cast using a silicone molding technique from the clay-sculptured prototypes. The 7 simulation scenarios included: 1) temporal craniotomy for a superficial temporal artery (STA)-middle cerebral artery (MCA) bypass using the M4 branch of the MCA; 2) pterional craniotomy and transsylvian approach for STA-M2 bypass; 3) bifrontal craniotomy and interhemispheric approach for side-to-side bypass using the A3 branches of the anterior cerebral artery; 4) far lateral craniotomy and transcerebellomedullary approach for a posterior inferior cerebellar artery (PICA)-PICA bypass or 5) PICA reanastomosis; 6) orbitozygomatic craniotomy and transsylvian-subtemporal approach for a posterior cerebral artery bypass; and 7) extended retrosigmoid craniotomy and transcerebellopontine approach for an occipital artery-anterior inferior cerebellar artery bypass. Experienced neurosurgeons evaluated each model by practicing the aforementioned bypasses on the models. Face and content validities were assessed using the bypass participant survey. A workflow for model production was developed, and these models were used during microsurgical courses at 2 neurosurgical institutions. Each model is accompanied by a corresponding prototypical case and surgical video, creating a simulation scenario. Seven experienced cerebrovascular neurosurgeons practiced microvascular anastomoses on each of the models and completed surveys. They reported that actual anastomosis within a specific approach was well replicated by the models, and difficulty was comparable to that for real surgery, which confirms the face validity of the models. All experts stated that practice using these models may improve bypass technique, instrument handling, and surgical technique when applied to patients, confirming the content validity of the models. The 7 bypasses simulation set includes novel models that effectively simulate surgical scenarios of a bypass within distinct deep anatomical corridors, as well as hand and operator positions. These models use artificial materials, are reusable, and can be implemented for personal training and during microsurgical courses.

A novel, reusable, realistic neurosurgical training simulator for cerebrovascular bypass surgery: Iatrotek® bypass simulator validation study and literature review.

Microanastomosis is a challenging technique requiring continuous training to be mastered. Several models have been proposed, but few effectively reflect a real bypass surgery; even fewer are reusable, most are not easily accessible, and the setting is often quite long. We aim to validate a simplified, ready-to-use, reusable, ergonomic bypass simulator. Twelve novice and two expert neurosurgeons completed eight End-to-End (EE), eight End-to-Side (ES), and eight Side-to-Side (SS) microanastomoses using 2-mm synthetic vessels. Data on time to perform bypass (TPB), number of sutures and time required to stop potential leaks were collected. After the last training, participants completed a Likert Like Survey for bypass simulator evaluation. Each participant was assessed using the Northwestern Objective Microanastomosis Assessment Tool (NOMAT). When comparing the first and last attempts, an improvement of the mean TPB was registered in both groups for the three types of microanastomosis. The improvement was always statistically significant in the novice group, while in the expert group, it was only significant for ES bypass. The NOMAT score improved in both groups, displaying statistical significance in the novices for EE bypass. The mean number of leakages, and the relative time for their resolution, also tended to progressively reduce in both groups by increasing the attempts. The Likert score expressed by the experts was slightly higher (25 vs. 24.58 by the novices). Our proposed bypass training model may represent a simplified, ready-to-use, reusable, ergonomic, and efficient system to improve eye-hand coordination and dexterity in performing microanastomoses.

Effects of Aspirin Therapy on Bypass Efficacy and Survival of Patients Receiving Direct Cerebral Revascularization.

Background: Both patency maintenance and neoangiogenesis contribute to cerebrovascular bypass efficacy. However, the combined impact of the aforementioned two indicators on postoperative revascularization following superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass has been less well elucidated. Meanwhile, there is a paucity of evidence with conflicting results about postoperative aspirin therapy. Objective: The objective of the study was to investigate the correlation between aspirin use and STA-MCA bypass efficacy, including patency, postoperative neoangiogenesis, and follow-up outcomes. Methods: A total of 181 MMD patients (201 procedures) undergoing STA-MCA bypass at our institution (2017–2019) were retrospectively reviewed. The bypass efficacy level and postoperative complications were compared between aspirin and non-aspirin groups. Results: Among 95 PS-matched pairs, the aspirin group presented a significantly more favorable bypass efficacy than the non-aspirin group [odds ratio (OR) 2.23, 95% confidence interval (CI) 1.11–4.61; p = 0.026]. Multivariate logistic regression analysis confirmed the profound impact of aspirin as an independent predictor of bypass efficacy [adjusted OR 2.91, 95% CI 1.34–6.68; p = 0.009]. A remarkable negative correlation was found between bypass efficacy and the rate of ischemic complications (Phi = −0.521). Postoperative aspirin therapy was associated with a non-significant trend toward a lower incidence of ischemic events [OR 0.73, 95% CI 0.23–2.19; p = 0.580]. No significant difference in bleeding rates was observed between aspirin and control groups [OR 1.00, 95% CI 0.12–8.48; p = 1.000]. Conclusion: Among patients undergoing STA-MCA bypass procedures, bypass efficacy is a good predictor of follow-up outcomes. Postoperative aspirin therapy can improve patency, neoangiogenesis, and overall bypass efficacy, thereby protecting against postoperative ischemic complications. Clinical Trial Registration: http://www.chictr.org.cn/, identifier CTR2100046178.

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.

Optimal Pressure in Bypass Graft to Prevent Failure Bypass Graft in Carotid Artery to Middle Cerebral Artery Bypass using Computational Fluid Dynamic Method

The proper pressure in bypass graft can produce adequate Cerebrovascular Transmural Pressure (CVTMP), which prevents cerebrovascular bypass failure. This study investigated the relation of sufficient pressure in Cerebrovascular bypass graft and inlet bypass angle using a Computational Fluid Dynamics (CFD) method. The geometry of this study was reconstructed from the CT modality of a specific patient. Region of Interest (ROI) was Internal Carotid Artery (ICA) to M2-Middle Cerebral Artery (MCA) without partial left sacrificed ICA. The bypass graft was then reconstructed in the diameter of the Saphenous Vein (SV) from unilateral ICA to M2-MCA. The inlet angle was varied from 15°, 30°, 45°, 60°, 75°, and 90°. Assuming a vessel wall was a rigid tube with a no-slip condition. Blood was incompressible Newtonian with 0.04 P of viscosity and 1.06 gr/cm3 of density. Inlet pressure was pulsatile blood flow velocity. The result shows 75° model had the highest pressure and pressure drop. The 15° model had the lowest pressure. The 30°, 45°, 60°, and 90° had similar pressure. Moreover, the 60° model had the lowest pressure drop among all models. This can be concluded that the 75° model may cause the exceeded CVTMP and bypass failure. However, there are more factors else that cause the bypass failure, such as types of bypass graft, additional preparation methods, and antithrombosis medications.

An innovative, reusable, high-fidelity neurosurgical training simulator for cerebrovascular bypass surgery: Iatrotek®didactic platform validation study and systematic Literature review

An innovative, reusable, high-fidelity neurosurgical training simulator for cerebrovascular bypass surgery: Iatrotek®didactic platform validation study and systematic Literature review

Pre- and Postoperative Cerebral Haemodynamic Assessments and Multidisciplinary Team Management for Patients Undergoing Cerebral Revascularization Procedures: 2 Case Reports

Background: Cerebrovascular bypasses are complex neurosurgical procedures with specific indications. Surgical risks and outcome are associated with the type of bypass intended and patient&rsquo;s underlying conditions. A multidisciplinary team approach is therefore pivotal in the management of these bypass patients. Objective: The aim of this study is to provide an overview of the perioperative haemodynamic assessments and management of patients undergoing cerebral revasculaization with 2 illustrative cases. Case Report: Case 1: A 40-year-old male with cerebrovascular occlusive condition and recurrent transient ischaemic attacks (TIA&rsquo;s) affecting his left side. Preoperative computed tomography (CT) brain perfusion and carbon dioxide (CO2) inhalation technique revealed poor cerebrovascular reserve (CVR) in the right middle cerebral artery (MCA) territory. The patient underwent a right superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery. Case 2: A 56-year-old female with a left giant cavernous sinus aneurysm presented with left-sided intractable facial pain. Preoperative cerebral digital subtraction angiography (DSA) with carotid compression test revealed inadequate collateral circulation. She underwent a high flow, common carotid-middle cerebral artery bypass with saphenous vein graft and trapping of the giant aneurysm. Results: Case 1: Postoperative computed tomography angiography (CTA) brain scan on day 1 confirmed graft patency. The patient improved rapidly in strength of the left arm and right leg. CT brain perfusion scan at 3 months showed improved brain perfusion and CVR. Case 2: Postoperative CTA brain on day 1 confirmed graft patency. On day 3 post-operatively, she developed self-limiting left-sided ophthalmoplegia, which completely resolved by 6 weeks. CTA brain at 5 months showed patency of the bypass graft. There was no further facial pain or ophthalmoplegia at the last follow-up. Conclusion: Although many new surgical techniques had been developed, the outcome for patients undergoing bypass surgery remains highly dependent on multidisciplinary teamwork, detailed preoperative haemodynamic assessment, patient selection and perioperative care. Keywords: Cerebrovascular bypass; EC-IC bypass; STA-MCA bypass; Cerebral ischaemia; Cerebrovacular reserve; Balloon occlusion test

Needle Parking Interrupted Suturing Technique for Microvascular Anastomosis: A Technical Note.

Interrupted and continuous suturing are 2 common techniques for microvascular anastomosis in cerebrovascular surgery. One of the technical complexities of interrupted suturing includes the risk of losing the needle in between interrupted sutures during knot tying, which may result in unnecessary movements and wasted time. To report a new needle parking technique for microvascular anastomosis that addresses a needle control problem during interrupted suturing. The needle parking technique involves puncturing both vessel walls at the site of the next provisional suture and leaving the needle parked in place while the knots at the first suture are being made. The thread is then cut, the needle is pulled through, and the process is repeated. Illustrative cases in which the needle parking technique was used are presented. We also compared time of anastomosis completion between the conventional interrupted, needle parking interrupted, and continuous suturing techniques during an in vitro study on standardized artificial vessels. This technique is being used successfully by the senior author for various cerebrovascular bypass surgeries. The in vitro study demonstrated that the needle parking technique can be significantly faster than the conventional interrupted suturing technique and may be as fast as continuous suturing. Needle parking technique is a modification of conventional interrupted suturing and solves the problem of losing the needle during knot tying. This technique is simple, prevents unnecessary movements, and may result in a faster anastomosis time.

Effects and safety of aspirin use in patients after cerebrovascular bypass procedures

ObjectSuperficial temporal artery to middle cerebral artery (STA-MCA) bypass is the most effective treatment for Moyamoya disease (MMD). In this study, we aimed to assess whether aspirin improves STA-MCA bypass...

Cerebrovascular bypass for ruptured aneurysms: A case series

In patients with aneurysmal subarachnoid hemorrhage (aSAH) unfavorable for endovascular or traditional open surgical techniques, surgical revascularization strategies comprise one of remaining limited options. There is nonetheless a paucity of data on the safety and efficacy of bypass in aSAH. In this study, we aimed to investigate complications and outcomes in a cohort of patients with aSAH treated with bypass. A prospective single-surgeon database of consecutive patients treated for aSAH between 2013 and 2018 was retrospectively analyzed. Complications and functional status at discharge were recorded and analyzed for the patients that underwent bypass surgery. Forty patients with aSAH were treated with bypass surgery (23 extracranial-intracranial; 17 intracranial-intracranial). All-cause perioperative mortality was 13% (6 patients). At discharge and at mean 14-month follow up, respectively, 16/40 (40%) and 16/25 (64%) of patients achieved a Glasgow Outcome Score of 4–5. All-cause, in-hospital complications occurred in 28 patients (70%), of which any ischemic complication occurred in 20 patients (50%), 7 (18%) being open surgical complications. This work represents the largest modern series of bypass for aSAH to date. In cases of aSAH unfavorable for endovascular intervention or traditional open surgical techniques, bypass remains a viable option in this complex group of patients.

Three-dimensional Cerebrovascular Bypass Training. A New Low-Cost Home-Made Model

Three-dimensional Cerebrovascular Bypass Training. A New Low-Cost Home-Made Model

Moyamoya: An Update and Review.

This article is a clinical review of Moyamoya disease (MMD) and Moyamoya syndrome (MMS). We review the incidence, epidemiology, pathology, historical context, clinical and radiographic findings, diagnostic imaging modalities, radiographic grading systems, the effectiveness of medical, interventional, and surgical treatment, and some of the nuances of surgical treatment options. This article will help pediatricians, neurologists, neurosurgeons, and other clinical practitioners who are involved in caring for patients with this rare clinical entity.MMD is an intrinsic primary disease process that causes bilateral progressive stenosis of the anterior intracranial circulation with the involvement of the proximal portions of the intracranial internal carotid artery (ICA) extending to involve the proximal portions of the anterior cerebral artery (ACA) and middle cerebral artery (MCA); posterior circulation involvement is very rare. This causes a compensatory response where large numbers of smaller vessels such as the lenticulostriate arteries begin to enlarge and proliferate, which gives the angiographic appearance of a "Puff of Smoke", which is translated into Japanese as "Moyamoya”. MMS is a secondary process that occurs in response to another underlying pathological process that causes stenosis of intracranial blood vessels, such as radiation. For example, an external source of radiation causes stenosis of the ICA with a compensatory response of smaller blood vessels, which then enlarge and proliferate in response and has the same "Puff of Smoke" appearance on the diagnostic cerebral angiogram (DCA).Histological findings include an irregular internal elastic lamina with luminal narrowing, hyperplasia of the tunica media, and intimal thickening with vacuolar degeneration in smooth muscle cells in the tunica media. Compensation for diminishing blood supply occurs through angiogenesis, which causes the proliferation and enlargement of smaller collateral blood vessels to increase blood supply to under-perfused areas of the brain.MMD is rare in the United States, with just 0.086 newly diagnosed cases per 100,000 individuals per year, which is approximately one per million new cases annually. Risk factors for MMD include Eastern Asian ancestry and predisposing conditions such as neurofibromatosis and Down's syndrome.Clinically, patients often present with stroke signs and symptoms from cerebral ischemia. The proliferation of collateral blood vessels within the basal ganglia can produce movement disorders. Catheter-based DCA is the current gold standard for obtaining a diagnosis. CT perfusion allows preoperative identification of ischemic vascular territories, which may be amenable to surgical intervention. MRI enables rapid detection of acute ischemic stroke using diffusion-weighted Imaging (DWI) and apparent diffusion coefficient (ADC) sequences to assess for any diffusion restriction. Non-contrast CT of the head is used to rule out acute hemorrhage in the presentation of a progressive neurological deficit.The treatment option for Moyamoya is generally surgical; medical treatment has failed to halt disease progression and neuro-interventional techniques such as attempted stenting of stenosed vessels have failed. Surgical options include direct and indirect cerebrovascular bypass.

EC-IC Bypass; Our Experience of Cerebral Revascularization with Intraoperative Dual-Image Video Angiography (Diva).

Background:Extracranial-intracranial (EC-IC) arterial bypass has been used in the treatment of various cerebrovascular ischemic disease due to atherosclerosis or Moyamoya disease, skull base tumors encasing large IC artery or complex IC aneurysms.Aim:The aim is to analyze surgical technique (EC-IC bypass) and its outcome with intraoperative use of dual image video angiography (DIVA) and Doppler ultrasound.Materials and Methods:We studied in this article a series of 23 patients operated in Banbuntane Hotokukai Hospital, Fujita Health University, for which a superficial temporal artery-middle cerebral artery anastomosis was done for steno-occlusive disease, giant IC aneurysm or Moyamoya disease. The study was conducted between 2018 and 2020. We used dual-image video angiography (DIVA) and Doppler ultrasound to assess the luminal patency of anastomosis during the procedure.Results:In this study, three patients presented with Moyamoya disease, 4 had aneurysm, whereas 16 patients presented with the vascular steno-occlusive disease. The patients were divided into three categories (steno-occlusive disease, Moyamoya, and flow replacement for giant aneurysm). Dual image video angiography, along with intraoperative Doppler, helped us in the assessment of luminal patency of the anastomosis.Conclusion:Hemodynamic recovery after cerebrovascular bypass brings about a better outcome in ischemic stroke. The result of surgery improves with proper selection of patients with hemodynamic impairment (in Stage 2). With various modalities such as intraoperative Doppler, DIVA (Dual-image Video Angiography) and improved surgical techniques may aid in the reduction of complications and improve clinical outcome.

Superficial Temporal Artery–Middle Cerebral Artery Bypass Ex Vivo Hybrid Simulator: Face, Content, Construct, and Concurrent Validity

Cerebrovascular bypass surgical procedures require highly developed dexterity and refined bimanual technical skills. To attain such a level of prowess, neurosurgeons and residents have traditionally relied on "flat" models (without depth of field), such as chicken wings, live rats, silicone vessels, and other materials that stray far from the reality of the operating room, albeit more accessible. We have explored the use of a hybrid exvivo simulator that takes advantage of the availability of placenta vessels and retains the complexity of surgery performed on a human skull to create a more realistic method for the development of cerebrovascular bypass surgical skills. Twelve exvivo simulators were constructed using 3 human placentas and 1 synthetic human skull for each. Face, content, construct, and concurrent validity were assessed by 12 neurosurgeons (6 trained vascular surgeons and 6 general neurosurgeons) and compared with those of other bypass models. The fidelity grade was ranked as low (Linkert scale score, 1-2), medium (score, 3), and high (score, 4-5). The face and content validity of the model showed high fidelity to superficial temporal artery-middle cerebral artery bypass surgery. Construct validity showed that cerebrovascular neurosurgeons had better performance, and concurrent validity highlighted that all surgical steps were present. The simulator was found to have strong face and content, construct, and concurrent validity for microsurgical cerebrovascular training, allowing for simulation of all surgical steps of the bypass procedure. The hybrid simulator seems to be a promising method for shortening the bypass surgery learning curve. However, more studies are required to evaluate the predictive validity of the model.