Superficial Temporal Artery-middle Cerebral Artery Research Articles

Dramatic improvement with superficial temporal artery and middle cerebral artery bypass in acute ischemic stroke in a rural area without MRI and angiography

Stroke is a major cause of mortality and morbidity. The best therapeutic modality is the early identification of patients with stroke symptoms, correct interpretation of different neuroimaging techniques, and immediate provision of reperfusion therapy. Apart from conventional treatments, superficial temporal artery-middle cerebral artery (STA-MCA) bypass should be considered a treatment modality for acute ischemic stroke, with good results and early improvement in cerebral perfusion and neurological status. In the present case, in a patient clinically diagnosed with MCA infarction, early STA-MCA bypass 45 min after symptom onset resulted in rapid neurological recovery, and contrast-enhanced computed tomography showed that the anastomosis was functioning.

A regressed superficial temporal artery–middle cerebral artery bypass cannot accommodate a decrease in cerebral blood flow caused by a re-exacerbation of middle cerebral artery stenosis: illustrative case

BACKGROUND Early superficial temporal artery–middle cerebral artery (STA-MCA) bypass is sometimes considered a salvage therapy for acute MCA territory strokes that fail medical and/or endovascular treatment. OBSERVATIONS A 77-year-old man presented with left hemiparesis for 2 days. Conservative treatment was initiated without acute recanalization. A few hours after hospitalization, his symptoms worsened. An STA-MCA bypass was performed after completing diffusion-weighted imaging (DWI) and perfusion-weighted imaging and observing a DWI-clinical mismatch. After 2 months of rehabilitation, the patient was discharged to home. Magnetic resonance angiography (MRA) at discharge showed that the stenosis in the right MCA had become mild and that the STA-MCA bypass had regressed with increased antegrade blood flow. Two weeks after discharge, the patient experienced worsening left hemiplegia at night and called for emergency medical assistance the following day. Magnetic resonance imaging showed scattered infarcts in the subcortical border zone, and MRA showed progression of the right M1 stenosis, requiring repeat revascularization due to hemodynamic changes caused by the improvement and subsequent re-exacerbation of the MCA stenosis. LESSONS Early STA-MCA bypass for symptomatic and progressive MCA stenosis can be effective; however, symptomatic MCA stenosis can be histologically dynamic. Symptoms can improve or worsen in a short period of time after STA-MCA bypass. https://thejns.org/doi/10.3171/CASE24673

Prediction of cerebral infarction after bypass surgery in adult moyamoya disease: combing parameters on 4D perfusion CT with clinical related factors

ObjectiveThis study aimed to identify predictive factors for cerebral infarction after bypass surgery in adult patients with moyamoya disease (MMD) using quantitative parameters in 4D-CT perfusion software.MethodsA total of 108 patients who underwent combined revascularization, including superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis and encephalo-duro-myo-synangiosis (EDMS), in our hospital between September 2019 and August 2023 were analyzed retrospectively. Preoperative relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), relative mean transit time (rMTT), and relative time to maximum residual function (rTmax) perfusion parameters were obtained using 4D-CT perfusion software. These quantitative parameters, combined with related clinical and angiographic factors, were statistically analyzed using univariate and multivariate regression analyses to determine the significant predictors of cerebral infarction after bypass surgery.ResultsAcute cerebral infarction occurred in 12 patients postoperatively. Univariate analysis showed that a history of previous ischemic events (P = 0.024), higher Suzuki stage (P = 0.006), higher modified Rankin score (mRS) (P = 0.013), rCBV (P = 0.026), rMTT (P = 0.001), and rTmax (P < 0.001) were associated with postoperative cerebral infarction. Further multivariate regression analysis showed that a history of previous ischemic events (OR = 12.830, 95%CI = 1.854–875.672, P = 0.031) and higher rTmax (OR = 16.968, 95%CI = 2.035–141.451, P = 0.009) were independently associated with new postoperative cerebral infarction. The cutoff value for rTmax was 2.025 (AUC = 0.935).ConclusionsPrevious ischemic event history and rTmax greater than 2.025 are independent risk factors for predicting cerebral infarction after combined revascularization with high sensitivity in adult patients with MMD. These patients should be more cautious when deciding on combined revascularization.

Superficial temporal artery-middle cerebral artery bypass signal intensity in time of flight magnetic resonance angiography as a marker of cerebral perfusion after revascularization procedure in moyamoya disease patients

The study was conducted to evaluate whether superficial temporal artery-middle cerebral artery (STA-MCA) bypass signal intensity has any correlation with cerebral perfusion on arterial spin labeling (ASL) perfusion in patients with Moyamoya disease (MMD), who underwent cerebral revascularization. Seventeen patients, who had STA-MCA bypass, were enrolled in this observational study and subjected to be followed up with MRI at three months post-operative interval. Region of interest (ROI) was placed in time of flight magnetic resonance angiography (TOF-MRA) images on STA-MCA bypass on the side where surgery was done. Signal intensity (SI) values obtained were normalized by converting them into ratio by taking signal intensity values of the common carotid artery just before its bifurcation as the denominator. The obtained STA-MCA bypass SI ratios were then compared with normalized cerebral blood flow (CBF) values obtained on ASL perfusion to look for correlation. Data analysis was done using SPSS software version 20.0 and GraphPad Prism 6. Spearman’s rank correlation coefficient was calculated between TOF-MRA and ASL MR perfusion parameters. A statistically significant positive correlation was found between STA-MCA bypass signal intensity with CBF of the frontal lobe (r = 0.532; P = 0.0280), CBF of the parietal lobe (r = 0.716; P = 0.001), and CBF of the temporal lobe (r=0.52; P = 0.033). However, there was no significant correlation between STA-signal intensity and CBF of basal ganglia (r = 0.128; P = 0.626).

Revascularization with superficial temporal artery-middle cerebral artery anastomosis in spontaneous intracranial internal carotid artery dissection: illustrative case.

Because of ischemic symptoms, intracranial internal carotid artery (IICA) dissection has no established treatment guidelines. The authors report a case of IICA dissection in which an emergency superficial temporal artery-middle cerebral artery (STA-MCA) bypass was performed. A 46-year-old woman presented with a headache and left hemiplegia. Her cortical symptoms appeared on day 10, and an STA-MCA bypass was performed because of cerebral hypoperfusion. Her postoperative patency was good, and cortical symptoms improved. Contrast-enhanced magnetic resonance imaging (MRI) was performed in the acute phase with wall contrast. From day 18, the internal carotid artery delineation improved, and the patient was transferred for rehabilitation without worsening symptoms. A literature review of spontaneous IICA dissection with revascularization procedures was conducted to discuss the indications, timing, treatment modalities, and surgical outcomes. The STA-MCA bypass provides supplemental cerebral blood flow and can prevent critical complications. Contrast-enhanced MRI in the acute phase of dissection can show a wall contrast effect and assist in predicting disease progression. https://thejns.org/doi/10.3171/CASE24332.

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.

Flow capacity of a superficial temporal artery as a donor in a consecutive series of 100 patients with superficial temporal artery-middle cerebral artery bypass.

A superficial temporal artery-middle cerebral artery (STA-MCA) bypass is classically considered a low-flow bypass. It is known that the flow in the flow augmentation STA-MCA bypass is influenced by flow demand of the revascularized territory and can reach significantly higher values. The authors report their intraoperative flow measurement data in a consecutive series of 100 STA-MCA bypasses performed at their institution. Moreover, in a subanalysis, they show the postoperative bypass flow measured with quantitative MR angiography (qMRA) noninvasive optimal vessel analysis (NOVA). Between January 2013 and October 2023, 100 patients with acute, subacute, or chronic large-vessel occlusion (LVO) or moyamoya disease underwent a flow augmentation STA-MCA bypass revascularization at the authors' department with intraoperative bypass flow measurement. Patients with atherosclerotic LVO who underwent bypass surgery within a 6-week period following the onset of ischemic stroke symptoms were categorized into the acute bypass group, encompassing both acute and subacute LVO cases. Conversely, those who underwent bypass surgery > 6 weeks after the last occurrence of ischemic stroke were classified as the chronic group. Since May 2019, a consecutive subgroup of 37 patients received a postoperative (before discharge) bypass flow measurement with the qMRA-NOVA imaging tool. The mean ± SD intraoperative bypass flow in this consecutive series of 100 STA-MCA bypasses was 53.5 ± 28.8 ml/min (range 14-145 ml/min). In the subanalysis, there was no difference in the intraoperative flow capacity between the acute and chronic groups and between the moyamoya and acute groups. Patients in the moyamoya group showed a significantly higher flow rate in the STA-MCA bypass compared with the chronic group (63.0 ± 30.2 ml/min vs 48.4 ± 26.5 ml/min, p = 0.03). In a consecutive subanalysis of 37 STA-MCA bypass cases, postoperative flow measurements were also performed using qMRA-NOVA, showing a significant increase in the flow of STA-MCA bypasses after surgery compared with intraoperative flow measurements (mean intraoperative bypass flow rate vs qMRA-NOVA postoperative bypass flow rate: 73.4 ± 29.9 ml/min vs 111.3 ± 51.4 ml/min, p = 0.005). Using intraoperative and postoperative quantitative flow measurements of the STA, the data confirm that the flow in the flow augmentation STA-MCA bypass is influenced by the flow demand of the revascularized territory and can reach high values if needed. Moreover, the significant flow increase in the postoperative flow measurement using qMRA-NOVA demonstrates that the bypass can increase its flow over time.

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.

BOLD Cerebrovascular Reactivity and NOVA Quantitative MR Angiography in Adult Patients with Moyamoya Vasculopathy Undergoing Cerebral Bypass Surgery.

Revascularization surgery for the symptomatic hemisphere with hemodynamic impairment is effective for Moyamoya vasculopathy patients. However, careful patient selection is crucial and ideally supported by advanced quantitative hemodynamic imaging. Recently, blood oxygenation level-dependent cerebrovascular reactivity (BOLD-CVR) and quantitative magnetic resonance angiography with non-invasive optimal vessel analysis (qMRA-NOVA) have gained prominence in assessing these patients. This study aims to present the results of BOLD-CVR and qMRA-NOVA imaging along with the changes in cerebral hemodynamics and flow status following flow augmentation with superficial temporal artery-middle cerebral artery (STA-MCA) bypass in our Moyamoya vasculopathy patient cohort. Symptomatic patients with Moyamoya vasculopathy treated at the Clinical Neuroscience Center of the University Hospital Zurich who underwent hemodynamic and flow imaging (BOLD-CVR and qMRA-NOVA) before and after bypass were included in the analysis. Reduced hemispheric volume flow rates, as well as impaired BOLD-CVR, were measured in all 12 patients with Moyamoya vasculopathy before STA-MCA bypass surgery. Following the surgical procedure, post-operative BOLD-CVR demonstrated a non-significant increase in BOLD-CVR values within the revascularized, symptomatic middle cerebral artery territory and cerebral hemisphere. The results of the statistical tests should be viewed as indicative due to the small sample size. Additionally, post-operative qMRA-NOVA revealed a significant improvement in the hemispheric volume flow rate of the affected hemisphere due to the additional bypass flow rate. Our findings affirm the presence of hemodynamic and flow impairments in the symptomatic hemisphere of the Moyamoya vasculopathy patients. Bypass surgery proves effective in improving both BOLD-CVR impairment and the hemispheric volume flow rate in our patient cohort.

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.

Prediction of cerebral infarction after bypass surgery in adult moyamoya disease: using pulsatility index on TCD

BackgroundAt present, the most effective treatment for symptomatic moyamoya disease (MMD) is surgery. However, the high incidence of postoperative complications is a serious problem plaguing the surgical treatment of MMD, especially the acute cerebral infarction. Decreased cerebrovascular reserve is an independent risk factor for ischemic infarction, and the pulsatility index (PI) of transcranial Doppler (TCD) is a common intuitive index for evaluating intracranial vascular compliance. However, the relationship between PI and the occurrence of ischemic stroke after operation is unclear.ObjectiveTo explore whether the PI in the middle cerebral artery (MCA) could serve as a potential predictor for the occurrence of ischemic infarction after bypass surgery in MMD.MethodsWe performed a retrospective analysis of data from 71 patients who underwent combined revascularization surgery, including superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis and encephalo-duro-myo-synangiosis (EDMS). The patients were divided into two groups according to the median of ipsilateral MCA-PI before operation, low PI group (MCA-PI < 0.614) and high PI group (MCA-PI ≥ 0.614). Univariate and multivariate regression analysis were used to explore risk factors affecting the occurrence of postoperative cerebral infarction.ResultsAmong the 71 patients with moyamoya disease, 11 patients had cerebral infarction within one week after revascularization. Among them, 10 patients’ ipsilateral MCA-PI were less than 0.614, and another one’s MCA- PI is higher than 0.614. Univariate analysis showed that the lower ipsilateral MCA-PI (0.448 ± 0.109 vs. 0.637 ± 0.124; P = 0.001) and higher Suzuki stage (P = 0.025) were linked to postoperative cerebral infarction. Multivariate analysis revealed that lower ipsilateral MCA-PI was an independent risk factor for predicting postoperative cerebral infarction (adjusted OR = 14.063; 95% CI = 6.265 ~ 37.308; P = 0.009).ConclusionsA lower PI in the ipsilateral MCA may predict the cerebral infarction after combined revascularization surgery with high specificity. And combined revascularization appears to be safer for the moyamoya patients in early stages.

Combined Direct and Indirect Revascularisation With Superficial Sparing of Temporalis Muscle in Moyamoya Disease: Operative Technique: 2-Dimensional Operative Video.

The primary objective of revascularization surgery for moyamoya disease (MMD) is to augment cerebral blood flow and prevent disease progression.1 There are several options for bypass surgery, including direct methods such as superficial temporal artery-middle cerebral artery anastomosis, indirect bypasses such as encephalomyosynangiosis, encephaloduroarteriosynangiosis or encephaloduroarteriomyosynangiosis, or combined procedures.2-5 In our institution, we undertake a combined approach involving multiple low-flow bypasses and a modified indirect bypass technique, with additional attention to achieving an optimal cosmetic result. Given that MMD often affects young patients, considering cosmesis as a significant factor in managing this condition should be standard practice. We present our modified operative technique of a combined approach to revascularization surgery in patients with MMD with particular emphasis on the indirect bypass procedure. The temporalis muscle is divided in two parts in the sagittal plane where the deeper portion is mobilized to perform an EMS, and the superficial portion is reattached to the bone flap to maintain cosmetic symmetry. A 23-year-old woman presented with a 6-month history of transient left-sided hemiparesis on a background of MMD (previous left-sided revascularization surgery). Subsequent imaging demonstrated worsening right internal carotid artery stenosis. The patient and her family were extensively counseled and decision to proceed with right-sided bypass surgery was undertaken (Video). The patient had an unremarkable postoperative course and was discharged home on day 14. Institutional review board approval was not required in our institution. The patient consented to the procedure and to the publication of his/her images.

Bypass-Assisted Microsurgical Clipping for an Endovascular Treatment-Resistant Ruptured Internal Carotid-Posterior Communicating Artery Aneurysm, Recurring Two Decades Postinitial Clipping: 2-Dimensional Operative Video.

Salvage treatment of postclipping recurrent aneurysms remains challenging.1,2 The salvage microsurgical clipping is a possible intervention but sometimes difficult because of tissue adhesions around the aneurysm and previously installed clips; therefore, salvage coil embolization may have certain advantages.1-5 However, when coil embolization is not applicable,6 microsurgical clipping is a stand-alone curative treatment, requiring proficient and reliable microsurgical techniques. This article describes a unique case of a 70-year-old female patient complaining of a severe headache with subarachnoid hemorrhage due to a recurrent ruptured left internal carotid-posterior communicating artery aneurysm after microsurgical clipping 23 years ago. An initial attempt at coil embolization proved unsuccessful because of the aneurysm shape. Consequently, the salvage microsurgical clipping was planned. Given the additional time for trapping the internal carotid artery for the old clip removal, a superficial temporal artery-middle cerebral artery bypass was also planned. The operation entailed a superficial temporal artery-middle cerebral artery bypass, a Sylvian fissure dissection, the old clip removal, and aneurysm clipping. Intraoperatively, the complete aneurysm neck clipping was successfully performed without any complication, and patient postoperative course was uneventful. A wide surgical field should be obtained to be able to manipulate the aneurysm and old clip safely under a microscope. It is also important to temporarily trap the main artery to ensure removal of old clips and to prepare for intraprocedural ischemia using bypass after a precise assessment of hemodynamics before surgery. The patient provided informed consent for the procedure and the publication of the case along with its pertinent imaging, and this report was approved by the institutional review board at our hospital.

Waveform Analysis of Superficial Temporal Artery-Middle Cerebral Artery Bypass Graft in Revascularization Surgery for Moyamoya Disease

Introduction: Postoperative hyperperfusion syndrome (PHS) is a well-known complication following superficial temporal artery (STA)-middle cerebral artery (MCA) bypass for moyamoya disease (MMD). The early detection of postoperative radiological hyperperfusion (PRH), characterized by a transient increase in local cerebral blood flow (CBF), is crucial for the early diagnosis of PHS. This study aimed to investigate the effectiveness of waveform analysis for early PRH detection. Methods: We reviewed 52 consecutive patients who underwent STA-MCA bypass for MMD. Patients were divided into PRH and non-PRH groups based on the postoperative/preoperative CBF ratio. We collected the intraoperative bypass graft waveform and bypass flow data using a flowmeter. The pulsatile index (PI), an indicator of peripheral vascular resistance (PVR), was calculated from bypass flow data. Next, the newly proposed index of PVR, the ratio of the time from peak to 50% decay and to 100% decay (RT50), was calculated through waveform analysis. The values were then compared between the PRH and non-PRH groups. Results: Twenty-seven of the 52 patients met the inclusion criteria. Fourteen of these 27 patients showed PRH. The RT50, but not the PI, was significantly higher in the PRH group. Linear regression analysis revealed a significant correlation between the RT50 and PI. In the receiver operating characteristic for predicting PRH, the area under the curve of RT50 was 0.750, with a cutoff value of 0.255, a sensitivity of 0.928, and a specificity of 0.500. Conclusion: The RT50 obtained from waveform analysis is associated with PVR and can be useful for the early detection of PRH in patients with MMD.

Hemodynamic Effects of Tortuosity and Stenosis in Superficial Temporal Artery-Middle Cerebral Artery Bypass for Moyamoya Disease

BackgroundSuperficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery has been widely adopted in treating moyamoya disease (MMD). Geometric variations including high tortuosity and stenosis appear in many cases but the hemodynamic effects have not been comprehensively evaluated. AimWe aim to evaluate the hemodynamic effects of bypass geometry variations based on patient-specific data. Methods17 patients with MMD underwent STA-MCA bypass surgery with highly tortuous bypass geometry were included. For each patient, the original 3-dimensional structure of STA-MCA bypass was reconstruct from clinical imaging data. The bypass structure was virtually improved by removing the tortuosity and stenosis. Computational fluid dynamics (CFD) simulation was performed on both bypass structures under identical patient-specific condition. The simulated hemodynamic parameters of the bypass and its distal branches were compared between the original and virtually improved bypass geometries in all cases using paired t-test or Wilcoxon signed-rank test. The changes of hemodynamic parameters were compared between the cases with and without mild-to-moderate stenosis (44.0%-70.3% in diameter) in the bypass using t-test or Mann-Whitney U test. ResultsThe virtual improvement of bypass geometry significantly increased the flow rate of the bypass and its distal branches (p<0.05) and decreased the transcranial flow resistance (p<0.05). The hemodynamic changes in cases with stenosis removal were significantly higher than those without stenosis (p<0.05). ConclusionHigh tortuosity and stenosis can significantly change the hemodynamics of STA-MCA bypass, and the optimization of bypass geometry deserves further consideration.

Effectiveness of indirect revascularization for adult hemorrhagic moyamoya disease: a 10-year follow-up study.

The optimal surgical approach for hemorrhagic moyamoya disease (hMMD) continues to be a topic of debate. The authors' prior research demonstrated that both combined and indirect revascularization were efficacious. However, questions remain regarding the long-term prognosis consistency between these two treatments. Therefore, the objective of this study was to evaluate and compare the enduring effects of these surgical modalities on adult hMMD, extending the findings of the authors' previous studies. The authors recruited patients diagnosed with hMMD between 2010 and 2015. The patients were categorized into two groups: those who underwent combined revascularization (superficial temporal artery-middle cerebral artery bypass alongside dural reverse application) and those who underwent indirect revascularization (encephaloduroarteriosynangiosis [EDAS]). The primary and secondary endpoints of this study were instances of rebleeding, confirmed with CT scan, and death resulting from rebleeding, respectively. The authors estimated rebleeding-free and death-free survival rates by utilizing the Kaplan-Meier survival method. They used Cox regression to adjust for confounders and to evaluate the effects of the varying surgical modalities on the endpoints. After an average follow-up period of 114 months, 35 patients (28.6%) experienced 40 rebleeding events, yielding an average annual incidence of 3.5%. Of the 79 patients who received combined revascularization, 17 (21.5%) experienced rebleeding events. Similarly, of 43 patients who underwent EDAS, 18 (41.9%) experienced rebleeding events (p = 0.018). Most rebleeding instances occurred 61-120 months after surgery (21 patients [60%]), followed by 12-60 months (11 patients [31.4%]). Multivariate survival analysis highlighted significant differences in surgical outcomes (HR 0.33, 95% CI 0.15-0.74, p = 0.007). The authors observed that 8 patients (10.1%) died of rebleeding events in the combined group, as well as 10 patients (23.3%) in the EDAS group. Despite the lack of a statistically significant difference in mortality (p = 0.051), multivariable survival analysis found a significant difference (HR 0.31, 95% CI 0.10-0.97, p = 0.044). High rebleeding rates persist in adult hMMD patients, even after revascularization. Combined revascularization proved superior to EDAS in preventing long-term rebleeding. In contrast, EDAS alone did not display a clear effect on reducing long-term rebleeding rates.

Spontaneous development and involution of a de novo pseudoaneurysm at the superficial temporal artery-middle cerebral artery bypass anastomotic site in a patient with moyamoya disease: illustrative case.

De novo pseudoaneurysm formation is a rare complication of extracranial-intracranial bypass surgery. The authors report the case of a 28-year-old male who presented with new-onset right temporal and occipital ischemia who was found to have bilateral proximal internal carotid artery occlusion with collateral vasculature formation consistent with moyamoya disease. The patient underwent bilateral superficial temporal artery-middle cerebral artery bypasses. A de novo pseudoaneurysm was found at the left-sided bypass distal anastomotic site recipient vessel 1 month after the surgery. The pseudoaneurysm demonstrated a progressive reduction in size and eventual complete involution at 6 months after surgery. Limited literature reports extracranial-intracranial bypass-associated aneurysms treated primarily with either clipping or resection and reanastomosis. The authors demonstrate, for the first time, a progressively benign natural history course of an extracranial-intracranial bypass distal anastomotic site pseudoaneurysm.

Intraoperative evaluation of local cerebral hemodynamic change by laser speckle contrast imaging for predicting postoperative cerebral hyperperfusion during STA-MCA bypass in adult patients with moyamoya disease

Cerebral hyperperfusion (CHP) occurred frequently after direct superficial temporal artery–middle cerebral artery (STA-MCA) bypass surgery for moyamoya disease (MMD). We analyzed cortical microvascular density (CMD) and the change of cerebral blood flow (LΔCBF) using intraoperative laser speckle contrast imaging (LSCI) on 130 hemispheres of 95 consecutive adult patients with MMD. The demographic characteristics, cortical hemodynamic sources, bypass methods, intraoperative blood flow data, and relative CBF changes on single-photon emission computed tomography (SPECT) examination (SΔrCBF) were compared between the groups with and without CHP. The median values for CMD, LΔCBF, and SΔrCBF were significantly higher in the CHP group than in the non-CHP group (CMD 0.240 vs 0.206, P = 0.004; LΔCBF 2.285 vs 1.870, P < 0.001; SΔCBF 1.535 vs 1.260, P < 0.001). Multivariate analysis revealed that hemodynamic sources of recipient parasylvian cortical arteries from MCA (M-PSCAs), end-to-side (E-S) bypass method, CMD ≥ 0.217, and LΔCBF ≥ 1.985 were the risk factors for CHP. Intraoperative LSCI was useful for evaluating hemodynamics and predicting CHP in patients with MMD.

Comparison of IMD and ICG videoangiography in combined bypass surgery: a single-center study.

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass combined with an encephaloduromyosynangiosis (EDMS) had gained significant role in treating chronic cerebral ischemia. Invasiveness and costs of intraoperative digital subtraction angiography (DSA) limited its application in operations. To find the reliable parameters for determining bypass patency with intraoperative micro-Doppler (IMD) sonography and compare the diagnostic accuracy of indocyanine green (ICG) videoangiography with IMD in combined bypass. One hundred fifty bypass procedures were included and divided into patent and non-patent groups according to postoperative computed tomography angiography (CTA) within 72h. The surgical process was divided into four phases in the following order: preparation phase (phase 1), anastomosis phase (phase 2), the temporalis muscle closure phase (phase 3), and the bone flap closure phase (phase 4). The IMD parameters were compared between patent and non-patent groups, and then compared with the patency on CTA by statistical analyses. IMD with CTA, ICG videoangiography with CTA,IMD with ICGvideoangiography were performed to assess bypass patency. The agreement between methods was evaluated using kappa statistics. No significant differences of baseline characteristics were found between patent and non-patent group. Parameters in the STA were different between patent and non-patent groups in phases 2, 3, and 4. In patent group, Vm was apparently higher and PI was lower in phases 2, 3, and 4 compared with phase 1 (P < .001). In non-patent group, no differences of Vm and PI were found within inter-group. The best cutoff value of IMD in the STA to distinguish patent from non-patent bypasses was Vm in phase 4 > 17.5cm/s (sensitivity 94.2%, specificity 100%). In addition, the agreement for accessing bypass patency was moderate between ICGvideoangiography and CTA (kappa = 0.67), IMD and ICG videoangiography (kappa = 0.73), and good between IMD and CTA (kappa = 0.86). ICG videoangiography could directly display morphology changes of bypass. IMD could be used for providing half-quantitative parameters to assess bypass patency. Vm in phase 4 > 17.5cm/s suggesting the patency of bypass on CTA would be good. Also, compared with ICG videoangiography, IMD had more accuracy.