Bypass Surgery For Moyamoya Disease Research Articles

Five-Day Bed Rest Reduces Postoperative Intracerebral Hemorrhage After Direct Bypass for Moyamoya Disease

Postoperative intracerebral hemorrhage (ICH) after direct bypass surgery for Moyamoya disease could contribute to neurologic deterioration. The aim of this study was to evaluate the effectiveness of 5-day bed rest in reducing the occurrence of postoperative ICH. This study included 122 consecutive hemispheres in 87 Japanese adult MMD patients, composed of 80 control hemispheres from historical data and 42 hemispheres after 5-day bed rest. They all underwent direct bypass surgery. The incidence of postoperative ICH and neurologic deterioration assessed via the modified Rankin Scale were investigated and statistically analyzed. Postoperative ICH was observed in 9 out of the 80 (11.3%) control patients, but not in the 42 patients with 5-day bed rest. The incidence of postoperative ICH and neurologic deterioration via the modified Rankin Scale were significantly different between the 2 groups (P= 0.0268 and 0.0078, respectively). Univariate logistic analysis revealed that 5-day bed rest significantly reduced the incidence of postoperative ICH (P= 0.0048). Five-day bed rest after direct bypass surgery dramatically can reduce the incidence of postoperative ICH and neurologic deterioration after direct bypass surgery.

Risk factors for postoperative ischemic complications in pediatric moyamoya disease

BackgroundIschemic events are the most common postoperative complication in bypass surgery for moyamoya disease (MMD), but the risk factors for pediatric MMD remain unclear. The goal of the study was to investigate the risk factors for postoperative ischemic complications in pediatric MMD patients.MethodsWe retrospectively reviewed a consecutive series of pediatric MMD cases at Beijing Tiantan Hospital, Capital Medical University from June 2010 through June 2019. Preoperative clinical variables and radiographic findings were recorded, and logistic regression analysis was carried out to identify the risk factors for postoperative ischemic events.ResultsA total of 533 operations in 336 patients were included in this study. Postoperative complications occurred after 51 operations (9.6%), including 40/447 indirect bypass procedures, 9/70 direct bypass procedures, and 2/16 combined bypass procedures. Postoperative ischemic events were the most common complication and occurred in 30 patients after 31 procedures (8.9% per patient; 5.8% per operation), including 26/447 indirect bypass procedures, 4/70 direct bypass procedures, and 1/16 combined bypass procedures, and the incidence of these events did not differ significantly between indirect and non-indirect bypass (5.8% vs 5.8%; p = 0.999). Multivariate logistic regression analyses revealed that older age at operation (OR 1.129, 95% CI 1.011–1.260, p = 0.032) and posterior cerebral artery involvement (OR 2.587, 95% CI 1.030–6.496, p = 0.043) were significantly associated with postoperative ischemic events.ConclusionWe speculate that older age at operation and posterior cerebral artery involvement are risk factors for postoperative ischemic events in pediatric MMD patients.

Retinal Vasculature Changes after Bypass Surgery for Moyamoya Disease

A 48-year-old woman with slurred speech was diagnosed with Moyamoya disease. Digital subtraction angiography disclosed left ophthalmic artery originating from the internal carotid artery (Fig A, arrow), and supplied by orbital branches of the middle meningeal and facial artery (Fig A, arrowhead). Preoperative examinations showed normal superficial vascular complex (SVC) in the left eye (OS) on OCT angiography (Fig B). She underwent left extracranial-intracranial bypass from the superficial temporal artery to the middle cerebral artery.

Evaluation of Hemodynamic Change by Indocyanine Green-FLOW 800 Videoangiography Mapping: Prediction of Hyperperfusion Syndrome in Patients with Moyamoya Disease.

Objective Hyperperfusion syndrome (HPS) after bypass surgery for moyamoya disease (MMD) mainly results from redistribution of blood flow, which leads to poor outcomes, while effective methods to predict HPS are still lacking. Indocyanine green (ICG) videoangiography can assess regional cerebral blood flow changes semiquantitatively with the application of FLOW 800 software. The purpose of this study was to investigate whether the intraoperative evaluation of local hemodynamic changes around anastomotic sites using FLOW 800 videoangiography mapping can predict the incidence of HPS and clinical outcomes. Methods Of the patients who were diagnosed with MMD in our hospital between August 2018 and December 2019, who underwent superficial temporal artery-middle cerebral artery bypass surgeries, we investigated 65 hemispheres (in 62 patients) in which intraoperative ICG analysis was performed using FLOW 800 (Zeiss Meditec, Oberkochen, Germany) to evaluate the local cerebral hemodynamics before and after anastomosis. Regions of interest were set at more than 2 points on the brain surface according to the location and situation of recipient arteries in the surgical area. Peak cerebral blood volume (CBV), regional cerebral blood flow (CBF), and time to peak (TTP) were calculated from the selected points. As the data were available intraoperatively, anastomoses were performed in a suitable area. According to the occurrence of HPS, patients were divided into the asymptomatic and symptomatic groups, from which hemodynamic parameters were compared. Furthermore, ROC analysis was performed to determine the diagnostic accuracy of change rates in CBV, CBF, and TTP (i.e., ΔCBV, ΔCBF, and ΔTTP) for predicting HPS. Results Data from the 62 patients were analyzed, and all patients were closely assessed during hospitalization after the procedures. The values of ΔCBV and ΔCBF were significantly higher in the symptomatic group (p < 0.01), while ΔTTP is slightly lower in the symptomatic group with no statistical differences (p = 0.72). Hemodynamic parameters including ΔCBV and ΔCBF, calculated by FLOW 800, had high sensitivity and specificity according to the ROC curve (ΔCBV: AUC = 0.743, 95% CI, 0.605–0.881, p = 0.002; ΔCBF: AUC = 0.852, 95% CI, 0.750–0.954, p < 0.01), which could be used as predictors for HPS. Conclusions Intraoperative ICG-FLOW 800 videoangiography mapping is a safe method which can reflect hemodynamic characteristics in the surgical area for MMD, the findings of which correlate with the occurrence of HPS. Parameters including ΔCBV and ΔCBF are proven to be efficient in the prediction of HPS.

Hemodynamic study about cortical hyperintensity belt sign after direct bypass surgery for moyamoya disease

Transient neurological events (TNEs) are observed after direct bypass surgery in patients with moyamoya disease (MMD). Although a correlation between cortical hyperintensity belt signs (CHBs) and TNEs has been reported, the pathophysiology of CHBs is still unknown. The purpose of this study was to reveal the pathophysiology of CHBs by using dynamic susceptibility contrast-magnetic resonance imaging. Thirty patients with MMD were included in this study. We provided scores (0–2) for the existence of CHBs on postoperative FLAIR images. We placed the ROI for the presented area of CHBs in the images of cerebral blood flow, CBV, and MTT. We calculated the change of the hemodynamic parameters (increase ratio, IR) and analyzed the relationship between IRs, CHB scores, and TNEs. TNEs were observed in 15 cases (50%) and CHBs were detected in 28 cases (93%). TNEs showed significantly higher CHB scores than those without (p < 0.05). The group of CHB score 2 showed a significantly higher CBV IR than the group with of score 0 (p < 0.05). Patients with TNEs showed a significantly higher CBV IR than those without (p < 0.05). As for the cut-off level to predict an appearance of TNEs, the CBV IR was 1.36 by the Receiver Operating Characteristic analysis, and the sensitivity and specificity were 80% respectively. We hypothesize that the pathophysiology of the CHBs are vasogenic edemas because the postoperative CBV increase correlated with the CHBs.

Abstract TP488: Postoperative Remodeling of Donor Arteries on MR Angiography Can Predict Development of Surgical Collaterals in Moyamoya Disease

Object: The calibers of donor arteries can change dynamically after bypass surgery in moyamoya disease (MMD). The present study aimed to evaluate the cut-offs of caliber changes in donor arteries associated with good surgical revascularization and to assess the impact of clinical factors potentially related to bypass development. Methods: We studied 71 hemispheres of 30 adults and 16 children with MMD, who underwent combined revascularization. We quantitatively measured the calibers of the superficial temporal artery (STA), deep temporal artery (DTA), and middle meningeal artery (MMA) with magnetic resonance angiography (MRA) source images and calculated the postoperative caliber change ratios (CCRs), to assess direct and indirect bypass development. They were compared with the findings of digital subtraction angiography, in which revascularization areas were categorized into 3 groups (poor, good, and excellent). Results: In both adult and pediatric hemispheres, median STA and DTA CCRs were higher in better revascularization groups (p &lt; 0.05), while MMA CCRs were not significantly different among the groups. Receiver operation characteristic analysis revealed that the cut-off of &gt;1.1 and &gt;1.3 STA CCRs were associated with good direct revascularization in adult and pediatric hemispheres, respectively. The cut-off of &gt;1.6 and &gt;1.2 DTA CCRs were associated with good indirect revascularization in adult and pediatric hemispheres, respectively. Considering these cut-off values, STA and DTA CCRs showed high median values, irrespective of age, severity of cerebrovascular reserve, disease stage, and disease onset type. Conclusions: Caliber changes in STA and DTA can be easily measured by MRA, which could be indicators of direct and indirect bypass development. The combined bypass procedure could maximize revascularization in both adults and children with MMD.

Correlation between operative timing and efficacy of combined bypass surgery for moyamoya disease

Correlation between operative timing and efficacy of combined bypass surgery for moyamoya disease

A critical appraisal of bypass surgery in moyamoya disease.

Moyamoya disease (MMD) is a complex cerebrovascular disorder about which little is known. Conventionally, revascularization surgery is recommended for patients, despite an absence of conclusive data from adequate clinical trials. Underscoring the uncertainty that exists in treating MMD patients, investigators continue to present data comparing revascularization with conservative or medical management, most of which originates from East Asia where MMD is most prevalent. The purpose of this manuscript is to review contemporary large case series, randomized trials, and recent meta-analyses that compare surgical and medical treatments in adult patients with MMD, and to critically analyze the modern literature in the context of current practice standards. Data from the available literature is limited, but revascularization seems superior to conservative therapy in adult patients presenting with hemorrhage, and in preventing future hemorrhages. Conversely, evidence that surgery is superior to medical therapy is not convincing in adult patients presenting with cerebral ischemia, or for the prevention of future ischemic events. In contrast to East Asian populations, MMD in Europe and in the Americas is predominantly an ischemic disease that presents in adulthood. Adequate multinational trials are warranted.

Angiographic Outcomes of Direct and Combined Bypass Surgery in Moyamoya Disease.

Objective: To identify associated risk factors for the angiographic outcomes after direct and combined bypass surgery in moyamoya disease (MMD).Methods: All direct and combined bypass procedures performed from June 2009 to May 2015 were screened in this prospective cohort study. Patients who acquired presurgical and follow-up catheter angiography were included. Bypass patency and postoperative collateral formation were evaluated. Univariate and multivariate logistic regression analyses were performed to determine the influence factors for bypass patency and postoperative collateral formation.Results: In total, 188 consecutive bypass procedures were included. After an 18-month median follow-up, the anastomosis patency rate was 88.3%. Postoperative collateral formation was associated with the patency of the anastomosis (Gamma = 0.891, p < 0.001). Multivariate logistic regression analysis showed that presence of hemorrhage (OR, 0.298; 95% CI, 0.125–0.709; p = 0.006) was associated with obstructed anastomosis. Among the 188 bypass surgeries, 125 (63.2%) hemispheres had good postoperative collateral formation and 85 (36.8%) had poor postoperative collateral formation. Multivariate logistic regression analysis showed that younger age at operation (OR, 2.396; 95% CI, 1.231–4.664; p = 0.010) was associated with good postoperative collateral formation, while the poor postoperative collateral formation was related to presence of hemorrhage (OR, 0.329; 95% CI, 0.143–0.758; p = 0.009) and dilated anterior choroidal artery (OR, 0.472; 95% CI, 0.240–0.929; p = 0.030).Conclusions: This study has demonstrated that presence of hemorrhage predicts lower patency rates. Younger age at operation was associated with good postoperative collateral formation, while the poor postoperative collateral formation was related to presence of hemorrhage and dilated anterior choroidal artery.

Restoration of periventricular vasculature after direct bypass for moyamoya disease: intra-individual comparison.

While periventricular anastomosis, a unique abnormal vasculature in moyamoya disease, has been studied in relation to intracranial hemorrhage, no study has addressed its change after bypass surgery. The authors sought to test whether direct bypass surgery could restore normal periventricular vasculature. Patients who had undergone direct bypass surgery for moyamoya disease at a single institution were eligible for the study. Baseline, postoperative, and follow-up magnetic resonance angiography (MRA) scans were scheduled before surgery, after the first surgery, and 3 to 6months after contralateral second surgery, respectively. Sliding-thin-slab maximum-intensity-projection coronal MRA images of periventricular anastomoses were scored according to the three subtypes (lenticulostriate, thalamic, and choroidal anastomosis). Baseline and postoperative MRA images were compared to obtain a matched comparison of score changes in the surgical and nonsurgical hemispheres within individuals (intra-individual comparison). Of 110 patients, 42 were identified for intra-individual comparisons. The periventricular anastomosis score decreased significantly in the surgical hemispheres (median, 2 versus 1; p < 0.001), whereas the score remained unchanged in the nonsurgical hemispheres (median, 2 versus 2; p = 0.57); the score change varied significantly between the surgical and nonsurgical hemispheres (p < 0.001). Of the 104 periventricular-anastomosis-positive hemispheres undergoing surgery, 47 (45.2%) were assessed as negative in the follow-up MRA. Among the subtypes, choroidal anastomosis was most likely to be assessed as negative (79.7% of positive hemispheres). Periventricular vasculature can be restored after direct bypass. The likelihood of correction of choroidal anastomosis is a subject requiring further studies.

Multimodal neuronavigation-guided precision bypass in adult ischaemic patients with moyamoya disease: study protocol for a randomised controlled trial

IntroductionRevascularisation surgery is an important treatment of moyamoya disease (MMD). Several general methods of revascularisation had been used: direct, indirect and combined techniques. However, there had been no reports about...

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

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

Intraoperative evaluation of local cerebral hemodynamic change by indocyanine green videoangiography: prediction of incidence and duration of postoperative transient neurological events in patients with moyamoya disease.

Transient neurological events (TNEs) occur frequently in the acute phase after direct bypass surgery for moyamoya disease (MMD), but there is currently no way to predict them. FlowInsight is a specialized software for analyzing indocyanine green (ICG) videoangiography taken with a surgical microscope. The purpose of this study was to investigate whether intraoperative evaluation of local hemodynamic changes around anastomotic sites using FlowInsight could predict the incidence and duration of TNEs. From patients who were diagnosed with MMD in our hospital between August 2014 and March 2017 and who underwent superficial temporal artery-middle cerebral artery bypass surgery, we investigated 25 hemispheres (in 22 patients) in which intraoperative ICG analysis was performed using FlowInsight. To evaluate the local cerebral hemodynamics before and after anastomosis, regions of interest were set at 3 locations on the brain surface around the anastomotic site, and the mean cerebral blood flow (CBF), mean gradation (Grad), mean transit time (MTT), and mean time to peak (TTP) were calculated from the 3 regions of interest. Furthermore, the change rate in CBF (ΔCBF [%]) was calculated using the formula (postanastomosis mean CBF - preanastomosis mean CBF)/preanastomosis mean CBF. ΔGrad (%), ΔMTT (%), and ΔTTP (%) were similarly calculated. Postoperative stroke without TNE occurred in 2 of the 25 hemispheres. These 2 hemispheres (in 2 patients) were excluded from the study, and data from the remaining 23 hemispheres (in 20 patients) were analyzed. For each parameter (ΔCBF, ΔGrad, ΔMTT, and ΔTTP) calculated by FlowInsight, the difference between the groups with and without TNEs was significant. The median values for ΔCBF and ΔGrad were significantly higher in the TNE group than in the no-TNE group (ΔCBF 30.13 vs 3.54, p = 0.0106; ΔGrad 62.05 vs 10.78, p = 0.00435), whereas the median values for ΔMTT and ΔTTP were significantly lower in the TNE group (ΔMTT -16.90 vs -7.393, p = 0.023; ΔTTP -29.07 vs -7.02, p = 0.00342). Comparison of the area under the curve (AUC) for each parameter showed that ΔTTP had the highest AUC and was the parameter with the highest diagnostic accuracy (AUC 0.857). The Youden index revealed that the optimal cutoff value of ΔTTP was -11.61 (sensitivity 77.8%, specificity 71.4%) as a predictor of TNEs. In addition, Spearman's rank correlation coefficients were calculated, and ΔCBF, ΔGrad, ΔMTT, and ΔTTP each showed a strong correlation with the duration of TNEs. The larger the change in each parameter, the longer the TNEs persisted. Intraoperative ICG videoangiography findings were correlated with the occurrence and duration of TNEs after direct bypass surgery for MMD. Screening for cases at high risk of TNEs can be achieved by ICG analysis using FlowInsight.

Abstract WP131: Repeat Bypass Surgery for Moyamoya Disease Refractory to Previous Surgery

Background and Purpose: Surgical revascularization is known to reduce subsequent incidence of ischemic and hemorrhagic stroke with low morbidity in moyamoya disease. However, repeat bypass surgery is required for a certain subgroup of patients, although the information on indication, surgical technique, and outcome is limited. Therefore, this study was aimed to precisely analyze clinical features, surgical technique, and long-term outcome of repeat bypass surgery for refractory moyamoya disease. Methods: This study included totally 20 surgeries for18 patients who underwent repeat bypass surgery because previous surgery was inadequate in 10 surgeries (Group A) or because the posterior cerebral artery was further involved after surgery in 10 (Group B). There were 7 males and 11 females. Their age ranged from one to 69 years. Precise radiological examinations were performed before surgery, using MRI, cerebral angiography, and SPECT. In Group A, all patients who previously underwent inadequate surgery repeated headache attack, TIA, or hemorrhagic stroke, and underwent repeat bypass surgery targeted to the non-revascularized area, using STA-MCA anastomosis and/or indirect synangiosis as appropriate. On the other hands, occipital artery to posterior cerebral artery (OA-PCA) anastomosis and/or indirect bypass was required in Group B who developed disease progression in the PCA. Results: All 18 patients successfully underwent repeat bypass surgery. Postoperative course was uneventful. Postoperative examinations revealed good revascularization in the operated hemispheres and the improvement of cerebral hemodynamics. Headache attack and TIA disappeared within 6 months at the latest after surgery. During follow-up periods, one (5.6% per person) of 18 patients died of recurrent hemorrhagic stroke two years after repeat bypass surgery. Conclusion: Repeat bypass surgery is feasible and effective to reduce further incidence of headache attack, TIA, and ischemic and hemorrhagic stroke. Through precise radiological analysis, surgical procedures should be planned to yield maximal therapeutic effects.

Abstract TMP81: Nationally Representative Estimates of Readmission Rates After Extracranial-Intracranial Bypass Surgery for Moyamoya Disease

Background: International trials have suggested benefit of extracranial- intracranial bypass (ECICB) for Moyamoya disease (MMD). However, nationally representative US data on demographics and adverse outcomes after ECICB in MMD are lacking. We aimed to estimate nationally representative 30, 60 and 90-day readmission rates for ischemic stroke (IS), subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH) after an index admission for MMD with ECICB. Methods: The Nationwide Readmissions Database contains data on &gt;14 million discharges for all payers and the uninsured in 2013. Index admissions for ECICB for MMD, and readmissions for IS, SAH, and ICH, were identified using validated International Classification of Diseases, 9th Revision, Clinical Modification codes. We summarized demographics, comorbidities, and the Charlson Comorbidity Index (CCI) during the index admission, and calculated 30-, 60-, and 90-day readmission rates per 100,000 index admissions. Preventable causes of admission were determined by Prevention Quality Indicators. Results: Among 201 index admissions for ECICB for MMD, mean age (SD) was 41.7 (12.6) years; 75% were female; 24% had diabetes; 53% had hypertension; 40% had hypercholesterolemia; and mean CCI (SD) was 3.2 (1.5). For concurrent or previous cerebrovascular events, 3% had ICH; 16% had IS; and 1% had SAH. ECICB was performed at large hospitals in 83%, urban hospitals in 85%, and teaching hospitals in 97%. 80% were discharged home. 1% died during index hospitalization. 34% had a readmission during follow-up, 3% of which were preventable. Leading reasons for readmission up to 90 days included MMD (62%), postoperative infection (10%), sickle cell crisis (4%), ischemic stroke (4%), epilepsy (2%), subdural hemorrhage (2%) and headache (2%). Readmission rates (per 100,000 index admissions) were 559 at 30 days, 1829 at 60 days, and 2027 at 90 days for IS. There were no readmissions for SAH or ICH. Conclusions: This analysis of nationally representative US data suggests that although readmission after ECICB for MMD is not uncommon, cerebral hemorrhagic events during the 90-day postoperative period are rare. Readmission for ischemic stroke, in comparison, is more prevalent, and only 3% of readmissions were preventable.

Quantitative assessment of changes in hemodynamics of the internal carotid artery after bypass surgery for moyamoya disease.

OBJECTIVE Although intracranial vessel remodeling has been observed in moyamoya disease, concerns remain regarding the effect of bypass surgery on hemodynamic changes within the internal carotid artery (ICA). The authors aimed to quantify the surgical effect of bypass surgery on bilateral ICAs in moyamoya disease and to estimate pressure drop (PD) along the length of the ICA to predict surgical outcomes. METHODS Records of patients who underwent bypass surgery for treatment of moyamoya disease and in whom flow rates were obtained pre- and postsurgery by quantitative MR angiography were retrospectively reviewed. Quantitative MR angiography and computational fluid dynamics were applied to measure morphological and hemodynamic changes during pre- and postbypass procedures. The results for vessel diameter, volumetric flow, PD, and mean wall shear stress along the length of the ICA were analyzed. Subgroup analysis was performed for the circle of Willis (CoW) configurations. RESULTS Twenty-three patients were included. The PD in ICAs on the surgical side (surgical ICAs) decreased by 21.18% (SD ± 30.1%) and increased by 11.75% (SD ± 28.6%) in ICAs on the nonsurgical side (contralateral ICAs) (p = 0.001). When the PD in contralateral ICAs was compared between patients with a complete or incomplete CoW, the authors found that the PDI in the former group decreased by 2.45% and increased by 20.88% in the latter (p = 0.05). Regression tests revealed that a greater postoperative decrease in PD corresponded to shrinking of ICAs (R2 = 0.22, p = 0.02). CONCLUSIONS PD may be used as a reliable biomechanical indicator for the assessment of surgical treatment outcomes. The vessel remodeling characteristics of contralateral ICA were related to CoW configurations.

Chronologic Evaluation of Cerebral Hemodynamics by Dynamic Susceptibility Contrast Magnetic Resonance Imaging After Indirect Bypass Surgery for Moyamoya Disease.

Although indirect bypass surgery is an effective treatment option for patients with ischemic-onset moyamoya disease (MMD), the time point after surgery at which the patient's hemodynamic status starts to improve and the time point at which the improvement reaches a maximum have not been known. The objective of the present study is to evaluate the hemodynamic status time course after indirect bypass surgery for MMD, using dynamic susceptibility contrast-magnetic resonance imaging (DSC-MRI). We retrospectively analyzed the cases of 25 patients with MMD (37 sides; mean age, 14.7 years; range, 3-36 years) who underwent indirect bypass surgery and repeated DSC-MRI measurement within 6 months after the operation. The difference in the mean transit time (MTT) between the target regions and the control region (cerebellum) was termed the MTT delay, and we measured the MTT delay's chronologic changes after surgery. The postoperative MTT delay was 1.81 ± 1.16 seconds within 1 week after surgery, 1.57 ± 1.01 at weeks 1-2, 1.55 ± 0.68 at weeks 2-4, 1.32 ± 0.68 at months 1-2, 0.95 ± 0.32 at months 2-3, and 0.77 ± 0.33 at months 3-6. Compared with the preoperative value (2.11 ± 0.98 seconds), the MTT delay decreased significantly from 2 to 4 weeks after surgery (P < 0.05). The amelioration of cerebral hemodynamics by indirect bypass surgery began soon after surgery and gradually reached a maximum at 3 months after surgery. DSC-MRI detected small changes in hemodynamic improvement, which are suspected to be caused by the initiation of angiogenesis and arteriogenesis in the early postoperative period.

Acceleration of blood flow as an indicator of improved hemodynamics after indirect bypass surgery in Moyamoya disease

Objective: The ultrasonography findings in the superficial temporal artery (STA) in Moyamoya disease patients treated with indirect bypass remain unclear. We evaluated the time-related changes in ultrasonography findings of the STA main trunk and branches in patients with Moyamoya disease who underwent encephalo-duro-arterio-synangiosis (EDAS). Patients and methodsPatients (n=21, 30 sides) with Moyamoya disease who underwent EDAS at Fukuoka University Hospital were prospectively registered between 2008 and 2015. EDAS using the frontal and parietal branches of the STA was adopted in an indirect bypass procedure. Mean velocity (MV) and resistance index (RI) were used as ultrasonography markers, and their changes over time in the STA main trunk and branches were assessed. ResultsThere was a significant increase in MV in both the STA main trunk (p=0.001) and branches (frontal: p=0.005, parietal: p=0.003) at 3 months after EDAS, whereas there was a decrease in RI at 14days after EDAS (main trunk: p <0.001, frontal: p <0.001, parietal: p=0.014). In subgroup analysis of patients divided by EDAS outcome, compared with before EDAS, there were significant differences at 3 months after EDAS in MV (responders: main trunk: p=0.002, frontal: p=0.001, parietal: p=0.001; non-responders: main trunk: p=0.093, frontal: p=0.24, parietal: p=0.96) and RI (responders: main trunk: p<0.001, frontal: p<0.001, parietal: p=0.006; non-responders: main trunk: p=0.17, frontal: p=0.12, parietal: p=0.17). ConclusionsMeasurement of MV may be useful for predicting outcome at 3 months after EDAS.

Correlation between reduction in microvascular transit time after superficial temporal artery-middle cerebral artery bypass surgery for moyamoya disease and the development of postoperative hyperperfusion syndrome.

OBJECTIVE Hyperperfusion syndrome (HPS) is a notable complication that causes various neurological symptoms after superficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery for moyamoya disease (MMD). The authors used intraoperative indocyanine green (ICG) videoangiography to measure the change in microvascular transit time (MVTT) after bypass surgery. An analysis was then conducted to identify the correlation between change in MVTT and presence of postoperative HPS. METHODS This study included 105 hemispheres of 81 patients with MMD who underwent STA-MCA single bypass surgery between January 2010 and January 2015. Intraoperative ICG videoangiography was performed before and after bypass surgery. The MVTT was calculated from the ICG time intensity curve recorded in the pial arterioles and venules. Multivariate logistic regression analysis was conducted to test the effect of multiple variables, including the change in MVTT after bypass surgery, on postoperative HPS. RESULTS Postoperative HPS developed in 28 (26.7%) of the 105 hemispheres operated on. MVTT was reduced significantly after bypass surgery (prebypass 5.34 ± 2.00 sec vs postbypass 4.12 ± 1.60 sec; p < 0.001). The difference between prebypass and postbypass MVTT values, defined as ΔMVTT, was significantly greater in the HPS group than in the non-HPS group (2.55 ± 2.66 sec vs 0.75 ± 1.78 sec; p < 0.001). Receiver operating characteristic curve analysis revealed that the optimal cutoff point of ΔMVTT was 2.6 seconds (sensitivity 46.4% and specificity 85.7% as a predictor of postoperative HPS). A ΔMVTT > 2.6 seconds was an independent predictor of HPS in multivariate analysis (hazard ratio 4.88, 95% CI 1.76-13.57; p = 0.002). CONCLUSIONS MVTT in patients with MMD was reduced significantly after bypass surgery. Patients with a ΔMVTT > 2.6 seconds tended to develop postoperative HPS. Because ΔMVTT can be easily measured during surgery, it is a useful diagnostic tool for identifying patients at high risk for HPS after STA-MCA bypass surgery for MMD.

Operative volume and outcomes of cerebrovascular neurosurgery in children.

OBJECTIVE The impact of procedural volume on the outcomes of cerebrovascular surgery in children has not been determined. In this study, the authors investigated the association of operative volume on the outcomes of cerebrovascular neurosurgery in pediatric patients. METHODS The authors performed a cohort study of all pediatric patients who underwent a cerebrovascular procedure between 2003 and 2012 and were registered in the Kids' Inpatient Database (KID). To control for confounding, the authors used multivariable regression models, propensity-score conditioning, and mixed-effects analysis to account for clustering at the hospital level. RESULTS During the study period, 1875 pediatric patients in the KID underwent cerebrovascular neurosurgery and met the inclusion criteria for the study; 204 patients (10.9%) underwent aneurysm clipping, 446 (23.8%) underwent coil insertion for an aneurysm, 827 (44.1%) underwent craniotomy for arteriovenous malformation resection, and 398 (21.2%) underwent bypass surgery for moyamoya disease. Mixed-effects multivariable regression analysis revealed that higher procedural volume was associated with fewer inpatient deaths (OR 0.58; 95% CI 0.40-0.85), a lower rate of discharges to a facility (OR 0.87; 95% CI 0.82-0.92), and shorter length of stay (adjusted difference -0.22; 95% CI -0.32 to -0.12). The results in propensity-adjusted multivariable models were robust. CONCLUSIONS In a national all-payer cohort of pediatric patients who underwent a cerebrovascular procedure, the authors found that higher procedural volume was associated with fewer deaths, a lower rate of discharges to a facility, and decreased lengths of stay. Regionalization initiatives should include directing children with such rare pathologies to a center of excellence.