Middle Cerebral Artery Bypass Surgery Research Articles

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.

Combination of intraoperative indocyanine green video-angiography FLOW 800 and computed tomography perfusion to assess the risk of cerebral hyperperfusion syndrome in chronic internal carotid artery occlusion patients after revascularization surgery.

To study the changes of corticocerebral hemodynamics in surgical area and postoperative hyperperfusion syndrome in patients with chronic internal carotid artery occlusion (CICAO) by intraoperative indocyanine green videoangiography (ICGA)-FLOW 800 and CT perfusion after superficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery. From October 2019 to January 2021, 77 patients diagnosed with CICAO underwent direct bypass surgery at Huadong hospital (affiliated with Fudan University) were enrolled. Regions of interest (ROIs) at STA, proximal MCA (PMCA), distal MCA (DMCA), cortical blood capillary (CBC), and cortical vein (CV) were identified after anastomosis by ICGV-FLOW 800 including peak fluorescence intensity (PFI), time to peak (TTP), and area under the time curve (AUC) of fluorescence intensity. All patients underwent perfusion-weighted CT before bypass surgery and those patients with HPS were verified by CTP after bypass. 14 patients with HPS were verified by perfusion-weighted CT after bypass. In HPS group, the AUCTTP of DMCA was significantly larger (T = -3.301, p = 0.004) and TTP of CBC was shorter (T = -2.929, p = 0.005) than patients in non-HPS group. The larger AUCTTP of DMCA (OR = 3.024, 95%CI 1.390-6.578, p = 0.0050) was an independent risk factor by further multivariate logistic regression analysis. The hemodynamic changes of cortical vessels during STA-MCA bypass surgery could be recorded accurately by ICGV-FLOW 800. Furthermore, the increased AUCTTP of DMCA and shorter TTP of CBC may be potential risk factors of HPS.

Aneurysm appearing at the anastomosis site 11 years after superficial temporal artery–middle cerebral artery bypass surgery: moyamoya disease with a rapidly growing aneurysm. Illustrative case

BACKGROUND Superficial temporal artery–middle cerebral artery (STA-MCA) bypass surgery is performed to prevent ischemia and hemorrhage in patients with moyamoya disease. Only a few reports have described aneurysms appearing around the anastomosis site after bypass surgery, and the underlying mechanism remains unknown. OBSERVATIONS The present case involved a 62-year-old woman who underwent STA-MCA bypass surgery for ischemic quasi-moyamoya disease at 46 years of age. Postoperatively, she underwent annual magnetic resonance imaging examinations. At 11 years after STA-MCA bypass surgery, a 3-mm aneurysm appeared at the anastomosis site. Four years later, headache developed and the aneurysm had grown to 5 mm. Craniotomy clipping was performed to prevent rupture. The patient was discharged home 2 weeks after surgery without any apparent complications. LESSONS Long-term observation is crucial after direct bypass surgery for moyamoya disease. Measures to prevent rupture should be considered for cases involving aneurysm complications.

Preoperative detailed evaluation intracranial artery stenosis using three-dimensional visualization analysis reduces the invasiveness of superficial temporal artery-middle cerebral artery bypass

Superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery is a common treatment for preventing cerebral ischemia in patients with intracranial artery stenosis. The aim of this study was to analyze the surgical outcomes of the STA-MCA bypass procedure, particularly with regard to the invasiveness of targeted bypass (TB) with preoperative planning using Amira® software. Consecutive patients with single STA-MCA bypass performed by a single neurosurgeon from January 2019 to May 2022 were included. The clinical parameters of seven TB patients were compared with those of 11 patients treated with the conventional method (CM). Compared with CM patients, TB using Amira® software patients had a shorter scalp incision (median [interquartile range]=11.2 [9.7-12.7] cm vs. 16.9 [16.0-17.7] cm, respectively; p=0.004], smaller craniotomy size (11.8 [11.5-14.4] cm2 vs. 20.9 [17.1-22.2] cm2, respectively; p=0.01], shorter surgery duration (201 [195-218] min vs. 277 [229-310] min, respectively; p=0.003], and less intraoperative bleeding (10 [10-20] g vs. 23 [20-50] g, respectively; p=0.033]. However, there were no differences in surgical complications between the two groups. Detailed preoperative evaluation using Amira® software can reduce the invasiveness of the STA-MCA bypass procedure.

True superficial temporal artery aneurysm: A case after extracranial-intracranial bypass surgery and a systematic review.

Nontraumatic true superficial temporal artery aneurysm (STAA) is rare, and its characteristics and pathogenesis are unclear. We report a case of STAA and performed a systematic review of PubMed, Scopus, and Web of Science using the keyword "superficial temporal artery aneurysm" to include studies on STAA reported through July 2022. We excluded studies on STAA associated with trauma, arterial dissection, infection, or vasculitis. A 63-year-old woman who underwent left superficial temporal artery (STA)-middle cerebral artery bypass surgery 8 years previously was diagnosed with an aneurysm located at the left STA. The blood flow volume estimated by ultrasonography was higher in the left STA than in the contralateral counterpart (114 mL/min vs. 32 mL/min). She underwent clipping surgery to prevent aneurysmal rupture without sequela. The lesion was diagnosed as a true aneurysm by histology. The systematic review identified 63 cases (including the present case) of nontraumatic true STAA. The median age of the patients was 57 (interquartile range [IQR]: 41-70) years. Most (90.5%) cases were detected as a palpable mass. Aneurysmal rupture occurred in only 1 (1.6%) case, despite the large size of aneurysms (median size: 13 [IQR: 8-20] mm) and the high frequency (33.3%) of aneurysmal growth during observation. Most (93.7%) patients underwent surgical resection of STAA without sequela. Our findings suggest that the pathogenesis of true STAA is promoted by hemodynamic stress. The systematic review clarified patients' and aneurysmal characteristics and treatment outcomes, providing further insight into the pathogenesis of nontraumatic true STAA.

Staged Common and External Carotid Artery Stenting Followed by Superficial Temporal Artery to Middle Cerebral Artery Bypass.

Superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery for internal carotid artery (ICA) occlusive disease necessarily requires sufficient external carotid artery (ECA) blood flow. Surgical bypass is therefore precluded if there is common carotid artery (CCA) occlusion. Here we present two such cases: one patient had a CCA occlusion and the other had an ICA occlusion and ECA stenosis. Both had failed medical management, and were therefore treated with angioplasty and stenting of the ECA, followed by STA-MCA bypass. We describe the clinical and radiologic outcomes of these cases, and remark on the potential pitfalls associated with this novel approach.

Letter to the Editor: “Can I Afford to Become a Neurosurgeon in the United Kingdom in the Current Atmosphere?”

Cerebral revascularization strategies through extracranial to intracranial bypass have been adopted in the management of complex intracranial aneurysms. The internal maxillary artery used as a donor in a bypass is an effective method. At present, there are few quantitative analyses of cerebral blood flow perfusion. The main focus of this study was to evaluate the effectiveness of blood perfusion after bypass grafting.From April 2015 to December 2017, 19 patients who underwent internal maxillary artery radial artery middle cerebral artery bypass surgery with unobstructed bypass vessels were selected. Cerebral blood flow perfusion before and after bypass surgery was quantitatively evaluated by computed tomography perfusion imaging. The cerebral blood perfusion in the region of interest was measured by computed tomography perfusion.The aneurysms were excised after trapping in 2 cases with mass effects and neural compression. Proximal occlusion of the parent artery was performed in 9 cases of fusiform or giant dissecting aneurysms. Trapping was performed after bypass surgery in 8 cases. Within 3 months after surgery, 17 patients had good outcomes. After the hypothesis test, there was a significant difference between the preoperative △cerebral blood volume and postoperative △cerebral blood volume in the anterior area of the semioval center cross section (P = 0.001 < 0.05).The internal maxillary artery as a bypass donor is an effective method that can provide sufficient intracranial blood perfusion, and there is usually no cerebral ischemia in the surrounding area.

Letter to the Editor Regarding “Burnout Among Neurosurgeons and Residents in Neurosurgery: A Systematic Review and Meta-Analysis of the Literature”

Cerebral revascularization strategies through extracranial to intracranial bypass have been adopted in the management of complex intracranial aneurysms. The internal maxillary artery used as a donor in a bypass is an effective method. At present, there are few quantitative analyses of cerebral blood flow perfusion. The main focus of this study was to evaluate the effectiveness of blood perfusion after bypass grafting.From April 2015 to December 2017, 19 patients who underwent internal maxillary artery radial artery middle cerebral artery bypass surgery with unobstructed bypass vessels were selected. Cerebral blood flow perfusion before and after bypass surgery was quantitatively evaluated by computed tomography perfusion imaging. The cerebral blood perfusion in the region of interest was measured by computed tomography perfusion.The aneurysms were excised after trapping in 2 cases with mass effects and neural compression. Proximal occlusion of the parent artery was performed in 9 cases of fusiform or giant dissecting aneurysms. Trapping was performed after bypass surgery in 8 cases. Within 3 months after surgery, 17 patients had good outcomes. After the hypothesis test, there was a significant difference between the preoperative △cerebral blood volume and postoperative △cerebral blood volume in the anterior area of the semioval center cross section (P = 0.001 < 0.05).The internal maxillary artery as a bypass donor is an effective method that can provide sufficient intracranial blood perfusion, and there is usually no cerebral ischemia in the surrounding area.

The Role of Early Superficial Temporal to Middle Cerebral Artery Bypass Revascularization Surgery in Middle Cerebral Artery‐Territory Strokes: A Systematic Review Study

Background To systematically summarize and critically review the available literature regarding the functional outcome of the urgent superficial temporal artery to the middle cerebral artery (MCA) bypass surgery in stroke patients associated with MCA lesions. Methods The current systematic review was conducted and reported using the Preferred Reporting Items for Systematic Reviews and Meta‐Analysis statement. Medline (PubMed), ISI Web of Science, Scopus, and google scholar (manually searches) were systematically searched up to August 2021. The eligibility criteria were defined as all the patients who had MCA‐territory strokes due to MCA/intradural internal carotid artery lesions that underwent same‐admission superficial temporal artery‐MCA bypass surgery. The strokes with cervical internal carotid artery and anterior cerebral artery lesions/strokes were excluded. The checklists produced by the US National Heart Lung and Blood Institute were used for quality assessment. Demographic variables, clinical findings, National Institutes of Health Stroke Scale scores, the time interval between symptoms to surgery, imaging results, endovascular treatments, surgical notes, mortality rate, follow‐up findings, modified Rankin scale scores, and all reported medical records were extracted and analyzed with SPSS software (ver. 23). P values ≤0.05 were considered meaningful. Results The initial search yielded 3050 records, and 13 articles met the inclusion criteria and entered this systematic review. A total of 165 patients were pooled for data analysis. Nine studies had data regarding neurological deficits before and after surgery. Except for 5 patients, the National Institutes of Health Stroke Scale score after the operation was the same or better than the preoperative score. Eleven out of 17 patients in 3 studies showed early neurological improvement (a decrease in National Institutes of Health Stroke Scale score of ≥4 points at 3 days) after bypass surgery. Functional outcome was stated in 10 studies. Overall, a good functional outcome (modified Rankin scale=0–2) was achieved in 9 out of 21 (42.1%) patients at discharge and in 44 out of 59 (74.5%) patients at 3 months follow‐up. Lower age was associated with favorable outcomes. Long‐term graft patency was excellent in 99.5% of patients. Postoperative hematoma and mortality (all noncranial) rates were 3% and 3.6%, respectively. Conclusion The current study suggests that early superficial temporal artery‐MCA revascularization should be considered an available option in younger patients (&lt;60‐year‐old) with MCA territory strokes who fail medical treatment.

Computed Tomography Perfusion Imaging Study of Intracranial Complex Aneurysms Treated by Internal Maxillary Artery Bypass Grafting

Cerebral revascularization strategies through extracranial to intracranial bypass have been adopted in the management of complex intracranial aneurysms. The internal maxillary artery used as a donor in a bypass is an effective method. At present, there are few quantitative analyses of cerebral blood flow perfusion. The main focus of this study was to evaluate the effectiveness of blood perfusion after bypass grafting. From April 2015 to December 2017, 19 patients who underwent internal maxillary artery radial artery middle cerebral artery bypass surgery with unobstructed bypass vessels were selected. Cerebral blood flow perfusion before and after bypass surgery was quantitatively evaluated by computed tomography perfusion imaging. The cerebral blood perfusion in the region of interest was measured by computed tomography perfusion. The aneurysms were excised after trapping in 2 cases with mass effects and neural compression. Proximal occlusion of the parent artery was performed in 9 cases of fusiform or giant dissecting aneurysms. Trapping was performed after bypass surgery in 8 cases. Within 3months after surgery, 17 patients had good outcomes. After the hypothesis test, there was a significant difference between the preoperative △cerebral blood volume and postoperative △cerebral blood volume in the anterior area of the semioval center cross section (P=0.001<0.05). The internal maxillary artery as a bypass donor is an effective method that can provide sufficient intracranial blood perfusion, and there is usually no cerebral ischemia in the surrounding area.

Superficial temporal artery-middle cerebral artery bypass for moyamoya disease treatment in Vietnam: A single-center prospective study

ObjectiveMoyamoya disease (MMD) is a rare progressive chronic cerebrovascular disease. There has been a lack of data on clinical characteristics and long-term outcomes in the treatment of MMD in Vietnam. Therefore, this study aims to investigate the clinical presentation of MMD in Vietnamese people as well as outcomes and complications during superficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery. MethodsThis single-center, prospective case series of MMD was conducted from January 2015 to December 2021 at the Department of Neurosurgery, University Medical Center at Ho Chi Minh City (UMC HCMC). Clinical characteristics, imaging, and modified Rankin Scale (mRS) of the patients were recorded preoperatively. We analyzed the surgical complications, postoperative mRS, patency of STA-MCA bypass, free TIA/stroke time after surgery, improvement of symptoms as well as quality of life at 6 months and 12 months after STA-MCA bypass surgery. Results39 patients with 55 bypass procedures (61.5% male, mean age 44.1 ± 13.9 years) were enrolled. At 3-month follow-up, all STA-MCA bypasses were patent. The surgical morbidity rate and mortality rate were noted at 3.6% and 0% per treated hemisphere, respectively. 94.87% of patients improved in their quality of life after surgery. Reduces in TIA symptom and headache were reported in 97% and 90% of cases, respectively. There was a statistically significant improvement in clinical status after 12 months of follow-up compared with that before surgery, as measured by mRS (0.97 ± 1.203 vs 2.33 ± 1.108). Good preoperative clinical condition (mRS ≤ 2) was noted as an important factor affecting the surgical outcomes. ConclusionsRevascularization surgery in patients with MMD is a safe and effective procedure. STA-MCA bypass surgery may improve the clinical status, reduce TIA/stroke event and improve the quality of life in MMD patients. Our findings suggest that it may be indicated for treatment of symptomatic MMD.

Recurrent Stroke in a Young Man with Moyamoya Disease on Medical Therapy: A Case Report

Moyamoya disease (MMD) is a rare intracranial vasculopathy characterized by the progressive occlusion of the terminal internal carotid arteries and their proximal branches. Various factors including genetic and inflammation are the proposed pathogenesis of MMD. We present a case of a 31-year-old man who had recurrent stroke secondary to MMD. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) demonstrated an infarct in the right middle cerebral artery (MCA) territory, and stenosis of the terminal right internal carotid artery (ICA) and its proximal branches. He initially declined surgical management and was treated with antiplatelet. After his third stroke, he finally underwent right superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery. He improved following rehabilitation with no further recurrence. The role of surgical revascularization in the prevention of stroke is well-described in the literature but evidence regarding medical therapy remain scarce and will be explored in this report.

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.

Patients Receiving Extracranial to Intracranial Bypass for Atherosclerotic Vessel Occlusion Today Differ Significantly From the COSS Population.

Despite the findings reported in the COSS (Carotid Occlusion Surgery Study), patients with atherosclerotic cerebrovascular disease continue to be referred for superficial temporal artery to middle cerebral artery bypass surgery. Here, we determined how today’s patients differ from the population reported in COSS. We retrospectively analyzed all patients that were referred to our Department for superficial temporal artery to middle cerebral artery bypass surgery of atherosclerotic cerebrovascular disease following the publication of COSS. Between 2012 and 2019, 179 patients were referred for 186 bypass surgeries. Ninety-one (51%) patients suffered atherosclerotic, unilateral internal carotid occlusion and 88 (49%) atherosclerotic multivessel disease. All patients had received intensive medical management. A single transitory ischemic attack or ischemic stroke within the last 120 days according to the inclusion criteria of COSS occurred in only 36 out of 179 (20%) patients, whereas 27 out of 179 (15%) suffered >1 transitory ischemic attack within 120 days, 109 out of 179 (61%) had recurrent minor ischemic stroke, and 7 out of 179 (4%) were hemodynamically unstable and required blood pressure maintenance. The distribution of symptoms did not differ between atherosclerotic unilateral internal carotid artery occlusion and atherosclerotic multivessel disease (P=0.376) but hemodynamic impairment was significantly greater in atherosclerotic multivessel disease (P<0.001 for atherosclerotic multivessel disease versus atherosclerotic unilateral internal carotid artery occlusion). The overall perioperative stroke rate was 4.3%. Patients referred for flow augmentation surgery today appear to suffer more severe symptoms and vessel occlusion patterns than patients reported in COSS. A new, carefully designed randomized controlled trial appears warranted, considering the still poor prognosis of severe atherosclerotic cerebrovascular disease.

The comparison of STA-MCA bypass and BMT for symptomatic internal carotid artery occlusion disease: a systematic review and meta-analysis of long-term outcome

BackgroundSuperficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery is now being widely used in moyamoya disease, and its therapeutic value in SICAO remains divergent.MethodsA systematic search was performed in PubMed, EMBASE, and Cochrane Databases in Feb. 2020 and updated in Jun. 2019. We have strict inclusion and exclusion criteria. Cochrane Bias Risk Assessment Tool was used to assess the quality of included RCTs. Review Manager 5.3 was used for analysis results in terms of comparing the STA-MCA bypass and BMT. For dichotomous variable outcomes, risk ratios (RRs) and 95% confidence intervals (95%CIs) were calculated for the assessment.ResultsThe total patient cohort consisted of 2419 patients, of whom 1188 (49.1%) patients had been grouped in STA-MCA bypass and 1231 (50.9%) patients had been divided into the BMT group. Mean follow-up of included patients was 29 months. The RR of the seven studies was 1.01, and the 95% confidence interval was .89–1.15, with statistical significance, Z = .13, P = .89, sustaining that STA-MCA bypass was not superior to BMT in symptomatic carotid artery occlusion disease.ConclusionsSTA-MCA bypass and BMT were associated with similar rates of a composite of long-term stroke. And the risk of long-term overall stroke was mildly higher with BMT. At present, each patient should receive more precise treatment, by reasonably assessing the individual differences of each patient to reduce the recurrence rate of stroke.

Color Doppler ultrasonography for predicting the patency of anastomosis after superficial temporal to middle cerebral artery bypass surgery

Color Doppler ultrasonography (CDUS) is used to evaluate the surgical success and postoperative hemodynamic changes of patients who receive superficial temporal to middle cerebral artery (STA-MCA) bypass surgery. Previous studies enrolled small populations, and difficulties interpreting the results have limited their use in clinical settings. We attempted to determine the feasibility of using CDUS to evaluate STA hemodynamics and identify the most reliable parameter as a new clinical implication for determining bypass patency. Twenty-six patients who underwent STA-MCA bypass surgery were prospectively enrolled. Four times CDUS and two times digital subtraction angiography (DSA) were performed. The CDUS parameters were compensated using the ratio of the operated to the non-operated sides (R1) and compared before and after surgery (R2). The CDUS parameters are then compared with the patency on DSA by statistical analyses. Increased CDUS parameters of the mean flow rate (MFR) and cross-sectional diameter (CSD) showed significant correlations with good patency on DSA. The R2 at 1 month was identified as the most reliable parameter for predicting the patency in both MFR and CSD. Their cutoff values were 1.475 and 1.15, respectively. CDUS can be utilized for predicting the patency after STA-MCA bypass surgery; if the postoperative (compensated and compared) CDUS parameters increased by more than 47.5% in the MFR or 15% in the CSD, the patency of the anastomosis on DSA would be good.

Long-Term Patency and Final Structure After Superficial Temporal Artery–Middle Cerebral Artery Bypass Surgery: A Retrospective Study

To investigate long-term bypass patency and final structure for patients who underwent superficial temporal artery (STA)-middle cerebral artery (MCA) bypass. This study retrospectively evaluated 20 patients who underwent STA-MCA bypass and had 2-year follow-up with cerebral angiography. Patients were divided into internal carotid artery occlusion (n= 11) and MCA occlusion or stenosis (n= 9) groups, and diagnosis was either arteriosclerotic (n= 14) or nonarteriosclerotic (n= 6) disease. Final bypass formation was examined with cerebral angiography at 2 years postoperatively. Diameters of the STA, middle meningeal artery (MMA), and deep temporal artery (DTA) were measured at preoperative angiography and at 2-year follow-up. No significant differences in STA, MMA, and DTA diameters were reported between the internal carotid artery versus MCA group. For patients with arteriosclerotic disease, thicker STA diameters were noted on preoperative angiography. For patients with nonarteriosclerotic disease, MMA and DTA dilatation was noted on 2-year follow-up imaging. For patients with arteriosclerotic disease, all direct bypasses were patent at 2 years. For patients with nonarteriosclerotic disease, remarkable angiogenesis was demonstrated. Long-term patency of a direct bypass may be correlated with arteriosclerotic or nonarteriosclerotic etiology. An indirect bypass route may develop in patients with nonarteriosclerotic disease; therefore, it is important to create a foundation for an indirect bypass with MMA and DTA preservation during craniotomy. In 2 patients with nonarteriosclerotic disease, STA remained the primary bypass foundation; however, the technique resembled novel angiogenesis after encephaloduroarteriosynangiosis and not direct STA-MCA bypass. Therefore, final bypass structure might be affected by disease etiology.

모야모야병의 뇌혈관 우회로 수술에서 영상의 변화와 부합하는 운동유발전위의 향상: 증례

Intraoperative neurophysiological monitoring (IONM) is an important method for detecting and potentially preventing postoperative neurologic deficit. Somatosensory evoked potentials (SSEP) and transcranial motor evoked potentials (tcMEP) are widely utilized for vascular surgery. A 24-year-old male with bilateral middle cerebral artery (MCA) occlusions, diagnosed with moyamoya disease, underwent right superficial temporal artery (STA)-MCA bypass surgery and encephalo-duro-arterio-synangiosis (EDAS). An increase in amplitude of tcMEP was noted when clipping, anastomosis, and clipping removal were completed, while SSEP remained normal. Postoperative brain MRI confirmed improvement of perfusion delay on right temporal lobe compared to initial MRI. This is the first report of IONM for moyamoya bypass surgery showing that improvement in MEP correlates with perfusion improvement.

Membrane Retraction Technique in Bypass Surgery for the Treatment of Adult Moyamoya Disease with Deep-Seated Recipient Artery

To introduce a membrane retraction technique that can provide good exposure of deep-seated recipient arteries in cortical sulci and simplify the anastomosis procedure. Only those adult patients with moyamoya disease who underwent superficial temporal artery to middle cerebral artery bypass surgery during which the suitable recipient arteries were located deep in cortical sulci were included in this retrospective study. By placing 10-0 prolene sutures to the arachnoid membrane of the 2 banks of sulcus, arachnoid retraction was applied to pull the sulcus apart and then the deep-seated recipient arteries were exposed. Standard end-to-side anastomosis was completed. The mean occlusion time and successful rate were recorded and compared with those of the normal procedure. From June to November 2019, 124 superficial temporal artery to middle cerebral artery bypass surgeries for the treatment of moyamoya disease were performed in Nanfang Hospital. The membrane retraction technique was used in 5 patients (5/110, 4.5%) and the success rates were 100%. The mean temporary occlusion time was 27.2 minutes. No procedure-related complications were observed. All patients recovered uneventfully. The postoperative angiograms confirmed good patency of bypass grafts in all 5 cases. The membrane retraction technique is an effective and safe method for the treatment of adult patients with moyamoya disease with deep-seated recipient arteries within the sulci.