Artery-middle Cerebral Artery Bypass Surgery Research Articles

Two Patients With Ipsilateral Cerebellar Hemorrhage After Superficial Temporal Artery-Middle Cerebral Artery Bypass Grafting.

To summarize the clinical experience of ipsilateral cerebellar hemorrhage after superficial temporal artery-middle cerebral artery bypass surgery. The clinical data of 2 patients with cerebellar hemorrhage after superficial temporal artery-middle cerebral artery bypass grafting were retrospectively collected, including 1 case with left cerebellar hemorrhage after left cerebral artery bypass grafting and 1 case with right cerebellar hemorrhage after right cerebral artery bypass grafting. The perioperative blood pressure, laboratory, and imaging data were analyzed. All patients had a history of hypertension, and their perioperative blood pressure was stable. Low-density lipoprotein cholesterol and high-density lipoprotein cholesterol were normal before the operation. Cerebral magnetic resonance imaging showed cerebral atherosclerosis and multiple ischemic cerebral infarcts. At 24 hours after surgery, the patients' continuous epidural low drainage was 260 mL and 160 mL, respectively. The amount of cerebellar bleeding was small, and no new sequelae were left after conservative treatment with drugs. Cerebellar hemorrhage after superficial temporal artery-middle cerebral artery bypass grafting is related to perioperative blood pressure fluctuation, hemodynamic changes, hemorrhagic transformation of ischemic lesions, and excessive cerebrospinal fluid drainage. Maintaining stable blood pressure during the perioperative period and avoiding excessive and rapid loss of cerebrospinal fluid after operation can reduce the occurrence of this complication.

Evaluation of Preoperative Low-flow Areas in STA-MCA Bypass Surgery Using Vascular Fusion Map Image.

The superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery requires an anastomosis of the STA to an MCA with diminished blood flow. However, identifying the precise location of the MCA with reduced flow preoperatively is challenging as it often remains nonvisualized. To address this issue, we developed a novel technique, the area target bypass (ATB) method, to infer the location of the responsible vessel for low-flow areas. The cornerstone of the ATB method lies in the utilization of the vascular fusion map (VFM). The VFM integrates 3D perfusion and 3D vascular images, enabling simultaneous evaluation of cerebral surface vessels and regions with reduced blood flow. This study aimed to assess the efficacy of the STA-MCA bypass surgery adopting the ATB method. Between August 2022 and March 2023, we conducted eight STA-MCA bypass surgeries using the ATB method. For each case, the VFM was generated using the MTT and DLY parameters, and blood flow improvement was evaluated based on the VFM score, determined by an average score from seven experts. In all cases, the target vessel was identified either preoperatively or during craniotomy, with postoperative patency of the STA-MCA bypass confirmed. Out of the eight cases, seven demonstrated improved blood flow with a VFM score exceeding 1. No complications were reported. The introduction of the ATB method has proven its potential in accurately pinpointing optimal anastomosis sites.

Assessing superficial temporal artery-middle cerebral artery anastomosis patency using FLOW 800 hemodynamics.

The objective of this study was to investigate the use of indocyanine green videoangiography with FLOW 800 hemodynamic parameters intraoperatively during superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery to predict patency prior to anastomosis performance. A retrospective and exploratory data analysis was conducted using FLOW 800 software prior to anastomosis to assess four regions of interest (ROIs; proximal and distal recipients and adjacent and remote gyri) for four hemodynamic parameters (speed, delay, rise time, and time to peak). Medical records were used to classify patients into flow and no-flow groups based on immediate or perioperative anastomosis patency. Hemodynamic parameters were compared using univariate and multivariate analyses. Principal component analysis was used to identify high risk of no flow (HRnf) and low risk of no flow (LRnf) groups, correlated with prospective angiographic follow-ups. Machine learning models were fitted to predict patency using FLOW 800 features, and the a posteriori effect of complication risk of those features was computed. A total of 39 cases underwent STA-MCA bypass surgery with complete FLOW 800 data collection. Thirty-five cases demonstrated flow after anastomosis revascularization and were compared with 4 cases with no flow after revascularization. Proximal and distal recipient speeds were significantly different between the no-flow and flow groups (proximal: 238.3 ± 120.8 and 138.5 ± 93.6, respectively [p < 0.001]; distal: 241.0 ± 117.0 and 142.1 ± 103.8, respectively [p < 0.05]). Based on principal component analysis, the HRnf group (n = 10) was characterized by high-flow speed (> 75th percentile) in all ROIs, whereas the LRnf group (n = 10) had contrasting patterns. In prospective long-term follow-up, 6 of 9 cases in the HRnf group, including the original no-flow cases, had no or low flow, whereas 8 of 8 cases in the LRnf group maintained robust flow. Machine learning models predicted patency failure with a mean F1 score of 0.930 and consistently relied on proximal recipient speed as the most important feature. Computation of posterior likelihood showed a 95.29% chance of patients having long-term patency given a lower proximal speed. These results suggest that a high proximal speed measured in the recipient vessel prior to anastomosis can elevate the risk of perioperative no flow and long-term reduction of flow. With an increased dataset size, continued FLOW 800-based ROI metric analysis could be used to guide intraoperative anastomosis site selection prior to anastomosis and predict patency outcome.

Multi-parameter MRI-Based Machine Learning Model to Evaluate the Efficacy of STA-MCA Bypass Surgery for Moyamoya Disease: A Pilot Study.

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery represents the primary treatment for Moyamoya disease (MMD), with its efficacy contingent upon collateral vessel development. This study aimed to develop and validate a machine learning (ML) model for the non-invasive assessment of STA-MCA bypass surgery efficacy in MMD. This study enrolled 118 MMD patients undergoing STA-MCA bypass surgery. Clinical features were screened to construct a clinical model. MRI features were extracted from the middle cerebral artery supply area using 3D Slicer and employed to build five ML models using logistic regression algorithm. The combined model was developed by integrating the radiomics score (Rad-score) with the clinical features. Model performance validation was conducted using ROC curves. Platelet count (PLT) was identified as a significant clinical feature for constructing the clinical model. A total of 3404 features (851 × 4) were extracted, and 15 optimal features were selected from each MRI sequence as predictive factors. Multivariable logistic regression identified PLT and Rad-score as independent parameters used for constructing the combined model. In the testing set, the AUC of the T1WI ML model [0.84 (95% CI, 0.70-0.97)] was higher than that of the clinical model [0.66 (95% CI, 0.46-0.86)] and the combined model [0.80 (95% CI, 0.66-0.95)]. The T1WI ML model can be used to assess the postoperative efficacy of STA-MCA bypass surgery for MMD.

Flow-augmentation STA-MCA bypass for acute and subacute ischemic stroke due to internal carotid artery occlusion and the role of advanced neuroimaging with hemodynamic and flow-measurement in the decision-making: preliminary data.

A major clinical challenge is the adequate identification of patients with acute (<1 week) and subacute (1-6 weeks) ischemic stroke due to internal carotid artery (ICA) occlusion who could benefit from a surgical revascularization after a failure of endovascular and/or medical treatment. Recently, two novel quantitative imaging modalities have been introduced: (I) quantitative magnetic resonance angiography (qMRA) with non-invasive optimal vessel analysis (NOVA) for quantification of blood flow in major cerebral arteries (in mL/min), and (II) blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging to assess cerebrovascular reactivity (CVR). The aim of this study is to present our cohort of patients who underwent surgical revascularization in the acute and subacute phase of ischemic stroke as well as to demonstrate the importance of hemodynamic and flow assessment for the decision-making regarding surgical revascularization in patients with acute and subacute stroke and ICA-occlusion. Symptomatic patients with acute and subacute ischemic stroke because of persistent ICA-occlusion despite optimal medical/endovascular recanalization therapy who were treated at the Neuroscience Clinical Center of the University Hospital Zurich underwent both BOLD-CVR and qMRA-NOVA to study the hemodynamic and collateral vessel status. Patients selected for surgical revascularization according to our previously published flowchart were included in this prospective cohort study. Repeated NOVA and BOLD-CVR investigations were done after bypass surgery as follow up as well as clinical follow up. Continuous BOLD-CVR and qMRA-NOVA variables were compared using paired Student t-test. Between May 2019 and September 2022, superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery was performed in 12 patients with acute and subacute stroke because of ICA-occlusion despite of optimal endovascular and/or medical treatment prior to the surgery. Impaired BOLD-CVR in the occluded vascular territory [MCA territory: ipsilateral vs. contralateral: -0.03±0.07 vs. 0.11±0.07 %BOLD/mmHgCO2, P<0.001] as well as reduced hemispheric flow with qMRA-NOVA (ipsilateral vs. contralateral: 228.00±54.62 vs. 384.50±70.99 mL/min, P=0.01) were measured indicating insufficient collateralization. Post-operative qMRA-NOVA showed improved hemispheric flow (via bypass) (pre-bypass vs. post-bypass: 236.60±76.45 vs. 334.20±131.33 mL/min, P=0.02) and the 3-month-follow-up with BOLD-CVR showed improved cerebral hemodynamics (MCA territory: pre-bypass vs. post-bypass: -0.01±0.05 vs. 0.06±0.03 %BOLD/mmHgCO2, P=0.02) in all patients studied. Quantitative assessment with BOLD-CVR and qMRA-NOVA allows us to evaluate the pre- and post-operative cerebral hemodynamics and collateral vessel status in patients with acute/subacute stroke due to ICA occlusion who may benefit from surgical revascularization after failure of endovascular/medical treatment.

Clinical effect of a modified superficial temporal artery-middle cerebral artery bypass surgery in Moyamoya disease treatment

BackgroundCerebral extracranial-intracranial (EC-IC) revascularization technique (superficial temporal artery-middle cerebral artery (STA-MCA) bypass grafting) has become the preferred surgical method for the treatment of Moyamoya disease (MMD). We attempted to completely free the two branches of the superficial temporal artery without disconnection. Extracranial and intracranial blood flow reconstruction were then modified by selectively performing a direct bypass technique on one branch and a patch fusion technique on the other of the STA based on the blood flow and the vascular diameter of the intracranial surface blood vessels.MethodsA series of modified STA-MCA bypass surgeries performed consecutively between March 2022 and March 2023 were reviewed and compared to conventional combined bypass surgeries performed during the same period. The following information was collected from all enrolled patients: demographic characteristics, clinical symptoms, and preoperative and postoperative imaging, including Suzuki stage and Matsushima grade. The modified Rankin scale (mRS) was used to assess the changes in neurological status before and after surgery.ResultsA total of 41 patients with Moyamoya disease (MMD) who underwent cerebral revascularization were included in this study, of which 30 were conventional revascularization and 11 were modified revascularization. The mean age was 49.91 years, and 18 (43.9%) of the patients were women. The modified group had a lower incidence of cerebral hyperperfusion syndrome (18.2%) than the conventional group (23.3%). After at least 3 months of follow-up, the bypass patency rate remained 100% in the modified group and 93.3% in the conventional group. All patients in the modified group achieved a better Matsushima grade (A + B), with six (54.5%) having an A and five (45.5%) having a B. In contrast, four patients (13.3%) in the conventional group had a Matsushima grade of C. In all, 72.8% of the modified group had postoperative mRS scores of 0 and 1, which was higher than that of the traditional group (63.3%).ConclusionThe improved STA-MCA bypass could provide blood flow to multiple cerebral ischemic areas, reduce excessive blood perfusion, and ensure blood supply to the scalp, with lower complications and better clinical benefits than the traditional combined bypass.

How I do it: direct pressure measurement in moyamoya bypass.

The direct quantitative measurement of donor and recipient pressures in patients with moyamoya vasculopathy (MMV) during superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery has yet to be reported in academic literature. Using a wireless pressure wire, we describe our approach to measuring seven pressure parameters in MMV patients step-by-step. Direct intraluminal pressure measurement of donor and recipient arteries provides a practical and accurate means to quantify cerebral hemodynamic parameters in MMV patients, enhancing understanding of individualized hemodynamic changes pre- and post-surgery.

Efficacyassessment of superficial temporal artery-middle cerebral artery bypass surgery in treating moyamoya diseasefrom a hemodynamic perspective: a pilot study using computational modeling and perfusion imaging.

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass is a common surgery in treating moyamoya disease (MMD) with occluded MCA. Computational fluid dynamics (CFD) simulation might provide a simple, non-invasive, and low-cost tool to evaluate the efficacy of STA-MCA surgery. We aim to quantitatively investigate the treatment efficacy of STA-MCA surgery in improving the blood flow of MMD patients using CFD simulation. This retrospective study included 11 MMD patients with occlusion around proximal MCA who underwent STA-MCA bypass surgery. CFD simulation was performed using patient-specific blood pressure and postoperative artery geometry. The volumetric flow rates of STA and the bypass, average flow velocity in the proximal segment of transcranial bypass, transcranial pressure drop, and transcranial flow resistance were measured and compared with a postoperative increment of cerebral blood flow (CBF) in MCA territories derived from perfusion imaging. Per-branch pressure drop from model inlet to bypass branch outlet was calculated. The volumetric flow rates of STA and the bypass were 80.84 ± 14.54mL/min and 46.03 ± 4.21mL/min. Average flow velocity in proximal bypass, transcranial pressure drop, and transcranial flow resistance were 0.19 ± 0.07m/s, 3.72 ± 3.10mmHg, and 6.54 ± 5.65 10-8Pasm-3. Postoperative mean increment of CBF in MCA territories was 16.03 ± 11.72mL·100g-1·min-1. Per-branch pressure drop was 10.96 ± 5.59mmHg and 7.26 ± 4.25mmHg in branches with and without stenosis. CFD simulation results are consistent with CBF observation in verifying the efficacy of STA-MCA bypass, where postoperative stenosis may influence the hemodynamics.

Variation of Superficial Temporal Artery-Middle Cerebral Artery(STA-MCA)Bypass

Superficial temporal artery-middle cerebral artery(STA-MCA)bypass surgery is a common operation in neurosurgery. There are several variations of this surgical method. We conducted a questionnaire survey on the details of surgical procedures in 171 neurosurgical institutes in Japan. Contrary to expectations, wide variations emerged in some surgical procedures, including the shape of skin and muscle incisions, the site of the temporary clip at the donor artery(STA), and the cutting method of the donor end. Western Japan institutions tended to vary more in terms of skin incision methods and donor cutting methods. It will likely be useful in the future to be aware of the numerous variations in surgical methods.

Fundamental Surgical Techniques of Superficial Temporal Artery:Middle Cerebral Artery (STA-MCA) Bypass

Superficial temporal artery-middle cerebral artery(STA-MCA)bypass surgery is necessary for vascular reconstruction in patients with hemodynamic ischemia, including moyamoya disease and complex aneurysms. This report introduces the fundamental techniques of STA-MCA bypass surgery practiced in my institute. Preoperative and perioperative management is important to minimize complications. During the procedure, the operator should keep a bloodless surgical field to facilitate the bypass. The vascular lumen and intima must be carefully observed during anastomosis, especially in moyamoya cases. In addition, this study emphasizes the importance of off-the-job training using animal or synthetic arteries because this technique includes special movements compared with that of other microsurgical procedures.

Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery: A Focus on Intimal Checks and Suturing

Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery: A Focus on Intimal Checks and Suturing

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

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.

Can Evoked Potential Changes during the Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery Predict Postoperative Improvement of Cerebral Perfusion and Functional Status?

Background: We investigated evoked potential (EP) changes during superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery and their correlations with imaging and clinical findings postoperatively. Methods: This retrospective study included patients who underwent STA-MCA bypass surgery due to ischemic stroke with large artery occlusion (MB group). Patients who underwent unruptured MCA aneurysm clipping were enrolled in the control group (MC group). Median and tibial somatosensory evoked potentials (SSEP), and motor evoked potentials recorded from the abductor pollicis brevis (APB-MEP) and abductor hallucis (AH-MEP) were measured intraoperatively. Modified Rankin scale (mRS) and perfusion-weighted imaging (PWI) related variables, i.e., mean transit time (MTT) and time to peak (TTP), were assessed. Results: Δmedian SSEP, ΔAPB-MEP, and ΔAH-MEP were significantly higher in the MB group than in the MC group (p = 0.027, p = 0.006, and p = 0.015, respectively). APB-MEP and AH-MEP amplitudes were significantly increased at the final measurement (p = 0.010 and p < 0.001, respectively). The ΔTTP asymmetry index was moderately correlated with ΔAPB-MEP (r = 0.573, p = 0.005) and ΔAH-MEP (r = 0.617, p = 0.002). ΔAPB-MEP was moderately correlated with ΔMTT (r = 0.429, p = 0.047) and ΔmRS at 1 month (r = 0.514, p = 0.015). Conclusions: MEP improvement during STA-MCA bypass surgery was partially correlated with PWI and mRS and could reflect the recovery in cerebral perfusion.

Cross-Comparison of 4-Dimensional Flow Magnetic Resonance Imaging and Intraoperative Middle Cerebral Artery Pressure Measurements Before and After Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery.

The hemodynamic changes after superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery are unclear. To clarify the hemodynamics by comparing flow parameters obtained by 4-dimensional (4D) flow magnetic resonance imaging (MRI) and intraoperative MCA pressure measurement. We recruited 23 patients who underwent STA-MCA bypass surgery for internal carotid artery (ICA) or MCA stenosis. We monitored intraoperative MCA, STA, and radial artery (RA) pressure. All patients underwent 4D flow MRI preoperatively and 3 wk after surgery to quantify the blood flow volume (BFV) of the ipsilateral ICA (BFViICA), contralateral ICA (BFVcICA), basilar artery (BFVBA), ipsilateral STA (BFViSTA), and contralateral STA (BFVcSTA). The sum of intracranial BFV was defined as BFVtotal. We compared BFV parameters and intraoperative pressure. BFViSTA significantly increased after surgery (P<.001). BFViICA and BFVBA significantly decreased after surgery (BFViICAP=.005; BFVBAP=.02). No significant difference was observed between BFVcICA before and after surgery. As a result, BFVtotal postoperatively increased by 6.8%; however, no significant difference was observed. Flow direction at M1 changed from antegrade to unclear after surgery in 5 patients. Intraoperative MCA pressure and MCA/RA pressure ratio significantly increased after surgery (P<.001). We found a stronger positive correlation between MCA pressure increase ratio and BFVtotal increase ratio in patients with lower pre-MCA pressure (r=0.907, P<.001). The visual and quantitative assessment of 4D flow MRI revealed that intracranial blood flow changes complementarily after STA-MCA bypass surgery. 4D flow MRI may detect the improvement of cerebral perfusion pressure.

Changes in Evoked Potentials during Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery: A Case Series Report

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass is a surgical treatment for ischemic stroke caused by large artery occlusion. Intraoperative neuropsychological monitoring (IONM) is useful for ensuring cerebral perfusion. Herein, we report 5 cases of patients with ischemic stroke who underwent STA-MCA bypass with IONM. We investigated whether the improved cerebral perfusion was reflected in real time on the evoked potentials (EP) of IONM. To measure changes in cerebral perfusion, all patients underwent pre- and post-operative perfusion-weighted imaging (PWI). Additionally, functional assessments were performed before and after the surgery. We found that the motor evoked potential (MEP) amplitudes showed a consistent increase at the end of surgery. The somatosensory evoked potential (SSEP) latencies decreased consistently, but this change was not large. SSEP amplitudes showed no consistent change. Most of the PWI findings and functional assessments of our patients also improved after the surgery. After bypass surgery, MEP showed more reliable and consistent changes than SSEP. Keywords: Cerebral revascularization; Cerebral blood flow; Intraoperative neurophysiological monitoring

Indocyanine green videoangiography for recipient vessel stratification in superficial temporal artery-middle cerebral artery bypass surgery.

In superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery, recipient vessel properties are likely one of the main reasons for bypass failure. In daily practice, most surgeons select the recipient with the largest diameter. However, selection of the ideal recipient remains debatable because there are no objective selection criteria if multiple potential recipients exist. Here, the authors assessed the benefit of using indocyanine green videoangiography (ICG-VA) to optimize recipient vessel selection in patients undergoing STA-MCA bypass surgery for hemodynamic compromise. All patients who had undergone STA-MCA bypass procedures with pre- and postanastomosis ICG-VA between 2010 and 2019 were eligible for inclusion in this study. The primary bypass surgeon was blinded to the preanastomosis ICG-VA. Preanastomosis white-light and ICG-VA images were compared to determine the identifiability of potential recipient vessels and pathological flow patterns. After completion of the anastomosis, a second (postanastomosis) ICG-VA image was used to analyze the flow increase within the chosen recipient based on the vessel diameter, initial recipient blood flow, initial sequence of appearance on ICG-VA, initial blood flow direction within the recipient, and orientation of the bypass graft. ICG-VA, FLOW 800, and intraoperative white-light images, as well as demographic, clinical, and radiographic patient data, were retrospectively analyzed by a clinician who was not directly involved in the patients' care. Sixty patients underwent 65 STA-MCA bypass procedures with pre- and postanastomosis ICG-VA. The ICG-VA permitted identification of a significantly higher number of potential recipient vessels (median 4, range 1-9) than the white-light images (median 2, range 1-5; p < 0.001), with detection of pathological flow patterns in 20% of all procedures. No association was found between the diameter and blood flow within potential recipients (Spearman r = 0.07, p = 0.69). After bypass grafting, the highest flow increase was noted in recipients with an initially low flow (p < 0.01), a late appearance (p < 0.01), and an initially retrograde flow direction (p = 0.02). Interestingly, flow increase was not significantly influenced by the recipient diameter (p = 0.09) or graft orientation (p = 0.44). ICG-VA facilitates identification of potential recipient vessels and detection of pathological flow patterns. Recipients with an initially low flow, a late appearance, and a retrograde flow seem to bear the highest potential for flow increase, possibly due to a higher hemodynamic need for revascularization.

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.

Analysis of Factors Related to Cerebral Infarction after Direct Bypass Surgery in Adults with Moyamoya Disease

Objective: High-risk factors of the patients with moyamoya disease (MMD) were analyzed to provide the basis for prediction and management of cerebral infarction after direct bypass surgery in adult MMD. Methods: 1. Retrospective analysis of clinical data was collected from adult MMD patients (n = 250) following superficial temporal artery-middle cerebral artery bypass surgery performed in our hospital from July 2013 to December 2017. Of the 250 patients, all underwent hemispherical bypass surgery, and bilateral surgery was performed on 14 patients. 2. Clinical data were analyzed based on sex, age, hypertension, diabetes, smoking history, history of alcohol use, presurgery cerebral infarction, transient ischemic attack, classification of clinical manifestations, clinical typing, Suzuki stage of surgical side, Suzuki stage of nonoperative side, preoperative Modified Rankin Scale (MRS), and lesions of the postoperative cycle or not. Results: 1. There were significant differences in classification of clinical manifestations, preoperative infarction, clinical typing, and Suzuki stage of nonoperative side (p < 0.05). 2. Logistic regression analysis showed that the independent factors affecting postoperative cerebral infarction were preoperative infarction and the Suzuki stage of nonoperative side (p < 0.05). The preoperative infarction (B 1.431, OR 4.184, 95% CI 1.217–14.382) and the Suzuki stage of nonoperative side (B 0.495, OR 1.640, 95% CI 1.207–2.227) were both risk factors. Conclusion: The possibility of a new cerebral infarction in postoperative patients with a history of cerebral infarction was greater. The Suzuki stages (I–VI) of the nonoperative side was higher and associated with an increased probability of cerebral infarction after surgery.

Salvage Treatment for Intraoperative Bypass Occlusion during Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery

Salvage Treatment for Intraoperative Bypass Occlusion during Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery