Superficial Temporal Artery-middle Cerebral Artery Bypass Surgery Research Articles

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

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

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

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

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.

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

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

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

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

Non-invasive assessment of cerebral microvascular changes for predicting postoperative cerebral hyperperfusion after surgical revascularisation for moyamoya disease: an arterial spin labelling MRI study

Cerebral hyperperfusion syndrome (CHPS) can result after anastomotic surgery as the reperfusion is established in chronically ischemic cerebral territories in patients of moyamoya disease (MMD). In this study, we have evaluated the feasibility of arterial spin labelling (ASL) perfusion MRI to predict cerebral hyperperfusion syndrome based on changes of cerebral blood flow (CBF) after revascularisation surgery in patients of MMD. Our prospective study included 25 patients with MMD who underwent superficial temporal artery-middle cerebral artery (STA-MCA) bypass with or without dural/muscle synangiosis. ASL MRI was performed before and 1-7days after surgery. On the side planned for operation, 5-mm ROI circle was drawn on the predetermined regions in frontal lobe, temporal lobe, parietal lobe and basal ganglia in proximal and distal territories of MCA to calculate ipsilateral CBF values (CBFi). An attempt was made to select the same location on contralateral side (non-operative) (CBFc) for each measurement for calculation of hemispheric normalised CBF (nCBFh) ratios. To adjust for inter individual variation among MR imagers and CBF, additional regions of interest were drawn within the cerebellum (CBFcbl) for cerebellar CBF normalised ratios (nCBFCbl). Of the 25 patients (26 operated hemispheres), 5 patients showed significant immediate postoperative symptoms suggestive of CHPS. Based on our findings, sensitivity and specificity of ASL perfusion to detect CHPS were evaluated. ASL was found to have 47-100% sensitivity and 45-88% specificity to detect CHPS. We have tried to calculate the prevalence of CHPS in postoperative patients of moyamoya disease, which in our study ranged from 6.83 to 40.70%. Based on our results, we concluded that ASL perfusion is an appropriate alternative to standard nuclear medicine studies to monitor the changes in perfusion after STA-MCA bypass surgery in moyamoya patients. ASL MR perfusion can be used to identify changes in cerebral blood flow (CBF) for early detection of cerebral hyperperfusion syndrome in patients with otherwise normal conventional MRI sequences with very high sensitivity but moderate specificity.

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

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

Local Cerebral Hemodynamics after Superficial Temporal Artery-Middle Cerebral Artery Bypass in Patients with Symptomatic Carotid Occlusions.

Context:Physiological insights into blood flow alterations in cortical vessels after superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery are important for the prognosis of bypass sustainability and hemodynamic patency.Aims:This study aims to assess the impact of STA-MCA bypass on local hemodynamics for patients with symptomatic carotid occlusions and Moyamoya disease.Settings and Design:This article presents a prospective nonrandomized study of intraoperative blood flow measurements in cortical branches of MCA and donor vessel before and after cerebral revascularization.Materials and Methods:Evaluation of local hemodynamic parameters was established for 112 patients with symptomatic carotid occlusive disease and cerebrovascular insufficiency during STA-MCA bypass surgery. We used intraoperative Doppler ultrasonography (89 patients – 72%), flowmetry (56 cases – 50%), and in 33 cases both methods. For physical justification of observed facts, we performed computational simulation with OpenFOAM CFD framework using Navier-Stokes nonstationary hemodynamic model.Statistical Analysis Used:All calculations were performed with IBM SPSS Statistics version 10.0 software. We used parametric (Z-test and Student's t-test) and nonparametric models (Wilcoxon, Mann–Whitney). For categorical values, we used Fisher's exact test.Results:Local cerebral hemodynamics after revascularization surgery significantly depended on initial perfusion deficit and the ability of bypass to reverse the blood flow in proximal parts of cortical artery (86 cases, 77%). Mechanism of cortical blood flow alteration was related to donor vessel cut flow value and potential consumption threshold of acceptor artery.Conclusions:Knowledge of hemodynamic principles of flow redistribution after STA-MCA bypass is important to improve bypass stainability and leads to better revascularization results.

Abstract WMP110: Improvement in Cortical Versus Subcortical Perfusion After Superficial Temporal Artery- Middle Cerebral Artery (MCA) Bypass in Patients With Severe Stenosis of Intracranial Carotid and MCA

Background and Objective: The role of superficial temporal artery-middle cerebral artery (STA-MCA) bypass in patients with symptomatic intracranial steno-occlusive disease has been evaluated scarcely. We have recently reported the improvement in clinical and various cerebral hemodynamic parameters after STA-MCA bypass surgery for severe steno-occlusive disease of intracranial internal carotid (ICA) or middle cerebral artery (MCA) and impaired cerebral vasodilatory reserve (CVR). Using acetazolamide challenged hexamethylpropyleneamine-oxime single-photon emission computed tomography (HMPAO-SPECT), we evaluated the differential improvement in metabolic perfusion in cortical and subcortical structures after STA-MCA bypass surgery. Methods: Patients with severe steno-occlusive disease of intracranial ICA or MCA underwent transcranial Doppler (TCD) for CVR assessment using breath-holding index (BHI). Patients with impaired BHI (&lt;0.69) were further evaluated with acetazolamide-challenged SPECT and STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. All patients underwent SPECT at 4±1 months. Using automated image analyzer, we evaluated differences in metabolic perfusion in cortical and subcortical regions. Results: Of the 126 patients (80 male, mean age 56yrs; range 23-78yrs) that fulfilled our inclusion criteria, 84 (67%) showed impaired CVR on SPECT. Fifty (60%) of them underwent STA-MCA bypass surgery. HMPAO-SPECT repeated 4±1 months after surgery showed significant improvement in all cases. Significantly better improvement (14.5%) in cerebral perfusion was noted in the cortical regions as compared to the subcortical regions (4.5%, p&lt;0.005). Conclusion: STA-MCA bypass surgery in carefully selected patients with symptomatic severe intracranial steno-occlusive disease results in significant improvement in cerebral perfusion, especially in the cortical regions.

Treatment of pediatric ischemia moyamoya disease by direct bypass combined with multiple burr hole

To investigate the treatment outcome of superficial temporal artery-middle cerebral artery bypass (STA-MCA) combined with multiple burr hole (MB) in pediatric ischemia moyamoya disease. A total of 31 pediatric patients with ischemic moyamoya disease who were admitted to Beijing Tiantan hospital from 2010 to 2013 were divided into two groups which were STA-MCA + MB surgery group (n = 16) and STA-MCA surgery only group (n = 15). In all patients, the number of patients with symptom improvement was 24 (77.4%), the number of patients with no symptom improvement was 5 (16.1%) and with symptom deterioration was 2 (6.5%). The postoperative modified rankin scale (mRS) in STA-MCA + MB group was significantly lower than that in STA-MCA group (P < 0.05). The treatment outcome of STA-MCA combined with MB is superior to STA-MCA bypass surgery only and doesn't increase the incidence of complication.

CT perfusion assessment of Moyamoya syndrome before and after direct revascularization (superficial temporal artery to middle cerebral artery bypass).

To evaluate the utility of CT perfusion (CTP) for the assessment of superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis in patients with Moyamoya syndrome (MMS). Twenty-four consecutive MMS patients, who underwent unilateral STA-MCA bypass surgery, received CTP before and after surgery. The relative perfusion parameter values of surgical hemispheres before treatment were compared with post-treatment values. All patients underwent CT angiography (CTA) before and after surgery in order to confirm the patency of bypass. The follow-up CTA after surgery clearly demonstrated 20 (20/24, 83.3 %) bypass arteries, whereas four (16.7 %) bypass arteries were occluded or very small. Postoperative rMTT and rTTP values (P < 0.05) of the surgical side were significantly lower than pre-operation. In patients (n = 20) with bypass patency, postoperative rCBF, rMTT and rTTP values (P < 0.05) of the surgical side were significantly improved. However, the differences of all parameters were not significant (P > 0.05) in the patients (n = 4) without bypass patency after revascularization. This study demonstrates that CTP can provide a crucial quantitative assessment of cerebral haemodynamic changes in MMS before and after STA-MCA anastomosis. Twenty-four MMS patients undergoing STA-MCA bypass received CTP pre- and post-surgery. Cerebral haemodynamics improved on the surgical side post-surgery on CTP maps. rCBF might have a better correlation with patency of the bypass artery. CTP can evaluate cerebral perfusion changes in MMS patients after cerebral revascularization.

Abstract 74: Improvement in Cerebral Hemodynamic Parameters and Outcome after Superficial Temporal Artery- Middle Cerebral Artery Bypass in Patients with Severe Steno-occlusive Disease of Intracranial Carotid and Middle Cerebral Artery

Background and Objective: Older and the recent extracranial-intracranial (EC/IC) bypass trials for symptomatic carotid occlusion failed to demonstrate reduction in stroke recurrence. However, role of superficial temporal artery-middle cerebral artery (STA-MCA) bypass in patients with symptomatic intracranial steno-occlusive disease has been evaluated scarcely. We evaluated serial changes in various cerebral hemodynamic parameters in patients with severe steno-occlusive disease of intracranial internal carotid (ICA) or middle cerebral artery (MCA) and impaired cerebral vasodilatory reserve (CVR), treated with STA-MCA bypass surgery or medical treatment. Methods: Patients with severe steno-occlusive disease of intracranial ICA or MCA underwent transcranial Doppler (TCD) ultrasonography and CVR assessment using breath-holding index (BHI). Patients with impaired BHI (&lt;0.69) were further evaluated with acetazolamide-challenged hexamethylpropyleneamine-oxime single-photon emission computed tomography (HMPAO-SPECT). STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. All patients underwent TCD and SPECT at 4±1 months and followed-up for cerebral ischemic events. Results: A total of 112patients (73males, mean age 56yrs; range 23-78yrs) were included. HMPAO-SPECT demonstrated impaired CVR in 77 (69%) patients. Of them, 46 underwent STA-MCA bypass while 31 received best medical treatment. TCD and acetazolamide-challenged HMPAO-SPECT repeated 4±1months showed significant improvement in STA-MCA bypass group. During follow-up (mean 34months; range 18-39months), only 6/46 (13%) patients in bypass group developed cerebral ischemic events as compared to 14/31 (45%) cases on medical therapy (absolute risk-reduction 32%, p=0.008). Conclusion: STA-MCA bypass surgery in carefully selected patients with symptomatic severe intracranial steno-occlusive disease results in significant improvement in hemodynamic parameters and reduction in stroke recurrence.

Abstract T MP26: Role of 99tc-hmpao Spect in the Assessment of Cerebral Hemodynamic Parameters After Superficial Temporal Artery- Middle Cerebral Artery Bypass in Patients With Severe Steno-Occlusive Disease of Intracranial Carotid and Middle Cerebral Artery

Background and Objective: Although superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery in patients with symptomatic carotid occlusion failed to demonstrate any benefit, its role in symptomatic intracranial steno-occlusive disease has been evaluated scarcely. We evaluated changes in hemodynamic parameters in patients with severe steno-occlusive disease of intracranial internal carotid (ICA) or middle cerebral artery (MCA) who underwent STA-MCA bypass for impaired cerebral vasodilatory reserve (CVR). Methods: Patients with severe steno-occlusive disease of intracranial ICA or MCA underwent transcranial Doppler (TCD) evaluation and CVR assessment using breath-holding index (BHI). Patients with impaired BHI (&lt;0.69) were further evaluated with acetazolamide-challenged 99Tc-HMPAO-SPECT. STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. TCD and SPECT were repeated in all patients at 4±1 months and they were followed-up for cerebral ischemic events. Results: Of the 126 patients (80 male, mean age 56yrs; range 23-78yrs) that fulfilled our inclusion criteria, 84 (67%) showed impaired CVR HMPAO-SPECT. Fifty (60%) of them underwent STA-MCA bypass while 34(40%) received best medical treatment. TCD and acetazolamide-challenged HMPAO-SPECT repeated 4±1 months after surgery showed significant improvement in STA-MCA bypass group. TCD BHI improved from a median (IQR) of -0.05 to 1.1 (p&lt;0.001). Compared to 98% patients with impaired CVR on pre-operative SPECT, only 20% showed abnormal results on post-operative imaging (p&lt;0.001). During follow-up (mean 35 months; range 8 to 49months), only 6/50 (12%) patients in bypass group developed cerebral ischemic events as compared to15/34 (44%) cases on medical therapy (absolute risk reduction 32%, p=0.006). Conclusion: 99Tc-HMPAO SPECT with acetazolamide challenge is a reliable tool for the assessment of cerebral vasodilatory reserve in patients with severe steno-occlusive disease of intracranial ICA or MCA. STA-MCA bypass surgery in carefully selected patients results in significant improvement in hemodynamic parameters and reduction in stroke recurrence.

Adult Moyamoya disease: 320-Multidetector row CT for evaluation of revascularization in STA–MCA bypasses surgery

PurposeTo evaluate the utility of 320-multidetector row whole-brain computed tomography perfusion (WBCTP) and whole-head subtracted dynamic angiography (WHSDCTA) for assessing the revascularization of blood flow after superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery in adults with Moyamoya disease (MD) in the short and long term. Patients and methods320-multidetector row WBCTP and WHSDCTA were applied in 20 patients with MD before and after surgery (for an average of 3 days and 3 months). The bypass arteries were investigated using WHSDCTA and compared with DSA. The regions of interests (ROIs) in the surgical and mirror sides of the cerebral cortex were drawn on a Vitrea Workstation. Cerebral blood volume (CBV), time to peak (TTP), cerebral blood flow (CBF), mean transit time (MTT), and delay time were recorded. Preoperative and postoperative perfusion parameters in the MCA distribution were compared using the paired t-test. ResultsWHSDCTA could clearly demonstrate 24 bypass arteries in 26 arteries for 20 patients, results which were in accordance with the results of digital subtraction angiography (DSA). When comparing preoperative values to those within 3 days after surgery, only TTP and delay time were significantly different (P<0.05). Values of CBV, TTP, CBF, delay time, and MTT 3 months after surgery were significantly different (P<0.05) from those of preoperative perfusion. ConclusionThese data suggest that 320-multidetector row WBCTP and WHSDCTA can be used to evaluate the revascularization of blood flow after STA–MCA bypass surgery in patients with MD in the short and long term.

Abstract WP161: Improvement in Cerebral Hemodynamic Parameters and outcomes after Superficial Temporal Artery- Middle Cerebral Artery Bypass in Patients with Severe Steno-occlusive Disease of Intracranial Carotid and Middle Cerebral Artery

Background and Objective —Older as well as the recent extracranial-intracranial (EC/IC) bypass trial in patients with symptomatic carotid occlusion failed to demonstrate reduction in stroke recurrence. However, the role of superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery in patients with symptomatic intracranial steno-occlusive disease has been evaluated scarcely. We evaluated the changes in various hemodynamic parameters in patients with severe steno-occlusive disease of intracranial internal carotid (ICA) or middle cerebral artery (MCA) who underwent STA-MCA bypass surgery for impaired cerebral vasodilatory reserve (CVR). Methods —Patients with severe steno-occlusive disease of intracranial ICA or MCA underwent transcranial Doppler (TCD) ultrasonography and CVR assessment using breath-holding index (BHI). Patients with impaired BHI (&lt;0.69) were further evaluated with acetazolamide-challenged hexamethylpropyleneamine oxime single-photon emission computed tomography (HMPAO-SPECT). STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. TCD and SPECT were repeated in all patients at 4±1 months and they were followed-up for cerebral ischemic events. Results —112 patients (73males, mean age 56yrs; range 23-78yrs) fulfilled our inclusion criteria. HMPAO-SPECT demonstrated impaired CVR in 77 (69%) patients. Forty-six of them underwent STA-MCA bypass while 31 received best medical treatment. TCD and acetazolamide-challenged HMPAO-SPECT repeated 4±1 months after surgery showed significant improvement in STA-MCA bypass group. During follow-up (mean 24 months; range 4 to 33months), only 6/46 (13%) patients in bypass group developed cerebral ischemic events as compared to14/31 (45%) cases on medical therapy (absolute risk reduction 32%, p=0.008). Conclusion —STA-MCA bypass surgery in carefully selected patients with symptomatic severe intracranial steno-occlusive disease results in significant improvement in hemodynamic parameters and reduction in stroke recurrence

The clinical utility of the Kopitnik arteriovenous malformation microclip during STA-MCA bypass surgery

PurposeYasagil temporary clips have been widely used in extracranial-intracranial (EC-IC) arterial bypass surgery. However, the extremely delicate vessels involved often require the application of finer clips. We report on the use of the Kopitnik arteriovenous malformation (AVM) microclip system for superficial temporal artery-middle cerebral artery (STA-MCA) bypass.MethodsKopitnik AVM microclips are new mechanical devices that are used during AVM surgery. They exert a pre-defined closing force of 50–70 g, and also feature a special, pyramid-shaped structure stamped on inner surfaces of the blades. These characteristics avoid vascular intimal injury and provide a secure grip. We prospectively studied their use in 15 patients requiring STA-MCA anastomosis.ResultsClinical results were excellent and there were no new ischemic events during 6-months’ follow-up.ConclusionsKopitnik AVM microclips have several advantages; they have small and variously sized clip blades (2, 3, 4 and 5 mm), and the small clip head allows the operator an excellent view of the pathology and clip status. The Kopitnik AVM microclip appears to be clinically effective and safe for EC-IC bypass surgery, especially when smaller vessels are involved.

Transient Hyperperfusion after Superficial Temporal Artery/Middle Cerebral Artery Bypass Surgery as a Possible Cause of Postoperative Transient Neurological Deterioration

Background: This study was designed to investigate the relationship between transient neurological deterioration and changes in cerebral perfusion after superficial temporal artery/middle cerebral artery (STA-MCA) bypass. Methods: Clinical characteristics of the patients with postoperative transient neurological deterioration were analyzed in 120 STA-MCA bypass procedures for ischemic cerebral diseases, such as atherosclerotic disease and moyamoya disease. Serial brain single-photon emission computed tomography (SPECT) was performed on 25 patients before surgery and on the third and tenth postoperative days. The hemispheric perfusion on SPECT was calculated semi-quantitatively using statistical parametric mapping and a probabilistic brain atlas. Results: Among 120 procedures, there were 4 permanent postoperative neurological deficits (3.3%) and 20 postoperative transient neurologic deteriorations with unknown etiology (17%). In 25 patients analyzed for postoperative perfusion changes, cerebral perfusion increased on the third postoperative day and the increased perfusion negatively correlated with preoperative perfusion (correlation coefficient = –0.77; p < 0.001). Temporal changes and the location of transient hyperperfusion on SPECT correlated with the time course and neurological deficits associated with postoperative transient neurological deterioration in 3 patients. Conclusions: Postoperative transient relative hyperperfusion is a common phenomenon and may be one of the causes of postoperative transient neurological deterioration after STA-MCA bypass surgery for ischemic cerebral diseases.

Standard superficial temporal artery-middle cerebral artery bypass surgery in hemodynamic cerebral ischemia: Indication and technique

Over the last years, new evidence has accumulated suggesting that hemodynamic compromise plays a key role in the manifestation of focal ischemic deficits in a subgroup of patients with occlusive cerebrovascular disease. For these patients, who are characterized by hemodynamic cerebral ischemia, superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery may represent an effective means to augment cerebral perfusion and, thereby, to improve their hemodynamic status. With new lessons learned from modern imaging techniques and with the availability of advanced functional cerebral blood flow studies, however, the management of this distinct patient population has changed considerably over the past years. In the present article we highlight our algorithm for identifying patients who are likely to profit from STA-MCA bypass surgery and outline the technical details of the operative procedure, as well as their preoperative and postoperative management.

Use of 123I-IMP brain SPET to predict outcome following STA-MCA bypass surgery: cerebral blood flow but not vasoreactivity is a predictive parameter.

Superficial temporal artery - middle cerebral artery (STA-MCA) bypass surgery might improve the cerebral blood flow (CBF) but fail to reduce the risk of post-surgical events such as ischaemic stroke. In this study, we studied retrospectively whether the risk of post-surgical events corresponded to the change in resting CBF and/or the change in vasoreactivity observed before and after STA-MCA surgery using N-isopropyl-I-123-p-iodoamphetamine (123I-IMP) brain single-photon emission tomography (SPET). 123I-IMP brain SPET images obtained at rest and following acetazolamide challenge both before and after STA-MCA surgery were studied in 30 patients. Resting CBF was estimated semiquantitatively using the resting count ratios of the middle cerebral artery (MCA) area to the cerebellum. Acetazolamide c hallenge was assumed to result in an average increase in flow of 40% in the cerebellum. The vasoreactive response was then estimated as the ratio of the change in counts (acetazolamide - rest) to the resting cerebellar counts multiplied by 1.4. We classified 14 patients (50.5 +/- 19.3 years) into group I, who h a change in their resting CBF from before to after surgery of >10%, and 16 patients (54.0 +/- 18.8 years) into group II, who had a change in their resting CBF from before to after surgery of ¿leq10%. Oxygen-15 positron emission tomography (PET) studies were performed in five patients from group I and five patients from group II. One post-surgical event occurred in group I while there were eight post-surgical events in group II (P<0.05). Resting CBF improved by 20.4% +/- 7.5% in group I and by 0.9% +/- 6.9% in group II patients after surgery (P<0.001). No significant difference in the improvement in vasoreactivity was observed between group I patients (32.6% +/- 17.7%) and group II patients (24.6% +/- 15.6%) following surgery. Patients in the group I PET subset showed normalization of oxygen extraction fraction (OEF) from 0.59 +/- 0.09 before surgery to 0.46 +/- 0.06 after surgery (P<0.05), while patients in the group II PET subset showed no statistical difference in OEF before surgery (0.58 +/- 0.14) and after surgery (0.54 +/- 0.05). We conclude that the outcome of STA-MCA bypass surgery can be predicted by the improvement in resting CBF but not by the improvement in vasoreactivity.