Multidelay MR Arterial Spin Labeling Perfusion Map for the Prediction of Cerebral Hyperperfusion After Carotid Endarterectomy.

BACKGROUND: Multidelay arterial spin labeling (ASL) generates time-resolved perfusion maps, which may provide sufficient and accurate hemodynamic information in carotid stenosis. PURPOSE: To use imaging markers derived from multidelay ASL magnetic resonance imaging (MRI) and to determine the optimal strategy for predicting cerebral hyperperfusion after carotid endarterectomy (CEA). STUDY TYPE: Prospective observational cohort. SUBJECTS: A total of 79 patients who underwent CEA for carotid stenosis. FIELD STRENGTH/SEQUENCE: A 3.0 T/pseudo-continuous ASL with three postlabeling delays of 1.0, 1.57, and 2.46 seconds using fast-spin echo readout. ASSESSMENT: Cerebral perfusion pressure, antegrade, and collateral flow were scored on a four-grade ordinal scale based on preoperative multidelay ASL perfusion maps. Simultaneously, quantitative hemodynamic parameters including cerebral blood flow (CBF), arterial transit time (ATT), relative CBF (rCBF) and relative ATT (rATT; ipsilateral/contralateral values) were calculated. On the CBF ratio map obtained through dividing postoperative by preoperative CBF map, regions of interest were placed covering ipsilateral middle cerebral artery territory. Three neuroradiologists conducted this procedure. Cerebral hyperperfusion was defined as a CBF ratio >2. STATISTICAL TESTS: Weighted κ values, independent sample t test, chi-square test, Mann-Whitney U-test, multivariable logistic regression analysis, receiver-operating characteristic curve analysis, and Delong test. Significance level was P < 0.05. RESULTS: Cerebral hyperperfusion was observed in 15 (19%) patients. Higher blood pressure (odd ratio [OR] = 1.08) and carotid near-occlusion (NO; OR = 7.31) were clinical risk factors for postoperative hyperperfusion. Poor ASL perfusion score (OR = 37.33), decreased CBF (OR = 0.74), prolonged ATT (OR = 1.02), lower rCBF (OR = 0.91), and higher rATT (OR = 1.12) were independent imaging predictors of hyperperfusion. ASL perfusion score exhibited the highest specificity (95.3%), while CBF exhibited the highest sensitivity (93.3%) for the prediction of hyperperfusion. When combined with ASL perfusion score, CBF and ATT, the predictive ability was significantly higher than using blood pressure and NO alone (AUC: 0.98 vs. 0.78). DATA CONCLUSIONS: Multidelay ASL can accurately predict cerebral hyperperfusion after CEA with high sensitivity and specificity. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 5.

Dural arteriovenous fistula presenting with stroke-like symptoms and regional cerebral hyperperfusion: a case report.

BACKGROUND: Non-hemorrhagic focal neurological deficit is one of the clinical manifestations of intracranial dural arteriovenous fistulas (DAVF). When symptoms appear suddenly, it is difficult to distinguish it from ischemic stroke in certain circumstances, which might easily lead to misdiagnosis. Here, we report a rare case of DAVF with sudden onset sensory aphasia mimicking hyperacute stroke but presented with unexpected regional hyperperfusion on the site corresponding to its symptoms. CASE PRESENTATION: A 76-year-old male with histories of atrial fibrillation and hypertension was admitted to the emergency department due to sudden sensory aphasia. The diagnosis of ischemic stroke was made based on clinical experience after non-contrast CT excluding hemorrhage. As in the absence of clear contraindication, the patient received intravenous thrombolysis. On the cerebral CT perfusion, the left temporal lobe, where the sensory speech center is located, was manifested as regional hyperperfusion. Thrombolysis was subsequently halted, but scheduled cranial imaging indicated hemorrhagic transformation. According to the radiological hint from cranial MRI, the patient was suspected of having DAVF, which was finally confirmed by cerebral digital subtraction angiography. CONCLUSION: When DAVF is presented as sudden onset focal neurological deficit, cranial CT perfusion at an early stage might reveal an abnormal hyperperfusion pattern. Clinicians should be aware of the diagnostic possibility of DAVF in this situation and double-review the CT angiography image to reduce missed diagnoses.

Prediction of cerebral hyperperfusion following carotid endarterectomy using intravoxel incoherent motion magnetic resonance imaging.

OBJECTIVES: One of the risk factors for cerebral hyperperfusion following carotid endarterectomy (CEA) is a chronic reduction in cerebral perfusion pressure due to internal carotid artery (ICA) stenosis, which is clinically detected as increased cerebral blood volume (CBV). The perfusion fraction (f) is one of the intra-voxel incoherent motion (IVIM) parameters obtained using magnetic resonance (MR) imaging that theoretically reflects CBV. The present study aimed to determine whether preoperative IVIM-f on MR imaging predicts development of cerebral hyperperfusion following CEA. MATERIALS AND METHODS: Sixty-eight patients with unilateral ICA stenosis (≥ 70%) underwent preoperative diffusion-weighted 3-T MR imaging, and IVIM-f maps were generated from these data. Quantitative brain perfusion single-photon emission computed tomography (SPECT) was performed before and immediately after CEA. Regions-of-interest (ROIs) were automatically placed in the bilateral middle cerebral artery territories in all images using a three-dimensional stereotactic ROI template, and affected-to-contralateral ratios in the ROIs were calculated on IVIM-f maps. RESULTS: Nine patients (13%) exhibited postoperative hyperperfusion (cerebral blood flow increases of ≥ 100% compared with preoperative values in the ROIs on brain perfusion SPECT). Only high IVIM-f ratios were significantly associated with the occurrence of postoperative hyperperfusion (95% confidence interval, 253.8-6774.2; p = 0.0031) on logistic regression analysis. The sensitivity, specificity, and positive and negative predictive values of the IVIM-f ratio to predict the occurrence of postoperative hyperperfusion were 100%, 81%, 45%, and 100%, respectively. CONCLUSIONS: Preoperative IVIM-f on MR imaging can predict development of cerebral hyperperfusion following CEA.

Intraoperative blood pressure lability carries a higher risk of headache after carotid endarterectomy.

OBJECTIVE: Cerebral hyperperfusion syndrome (CHS) is a rare but potentially devastating complication after carotid endarterectomies (CEA). Its symptoms range from new-onset unilateral headache (HA) to intracranial hemorrhage (ICH). Risk factors for CHS in the literature to date have not yet yielded a consensus. This study examines intraoperative and postoperative blood pressure variations as potential risk factors for HA. METHODS: A single-center retrospective review at a tertiary care center from January 2010 to November 2019 was performed. Inclusion criteria were all patients undergoing CEA for symptomatic or asymptomatic carotid disease. Patients with incomplete charts were excluded. Primary endpoints were new-onset unilateral HA or postoperative ICH. Data on intraoperative and postoperative mean arterial pressure (MAP), systolic blood pressure (SBP), the mode of endarterectomy, shunt placement, and contralateral carotid status were collected. RESULTS: There were 735 patients who met the inclusion criteria: 430 patients underwent modified eversion CEA (59%) and 305 patients for patch angioplasty (42%). The incidence of HA was 19% (n = 142) in our total cohort. Of the 19% with HA, 1.5% (n = 11) demonstrated no relief with analgesics and strict blood pressure control; noncontrast head computed tomography scans were performed subsequently. One patient (0.1%) had an ipsilateral ICH. Univariate analysis demonstrated that greater intraoperative MAP peak had the highest risk for HA (odds ratio [OR], 1.014; 95% confidence interval [CI], 1.007-1.022; P = .0002), followed by intraoperative MAP variability (OR, 1.011; 95% CI,1.005-1.018; P ≤ .0008), and peak intraoperative SBP (OR, 1.01; 95% CI, 1.004-1.015; P = .0011). An unpaired Student t test identified change in intraoperative MAP (P < .005), change in the SBP (P < .005), and peak SBP (P < .001) were significantly associated with HA. Interestingly, there was no significant difference between postoperative MAP variability and HA (P = .1). The mode of endarterectomy showed no statistically significant difference in risk for developing HA (OR, 1.165; 95%; 95% CI, 0.801-1.694; P = .42). CONCLUSIONS: Greater intraoperative variability in blood pressures are significantly associated with a higher risk of HA. Adhering to stricter intraoperative blood pressure parameters and limiting blood pressure variability may be beneficial at decreasing the incidence of CHS and its complications.

Arterial transit artifacts on arterial spin labeling MRI can predict cerebral hyperperfusion after carotid endarterectomy: an initial study.

OBJECTIVES: To investigate whether preoperative arterial spin labeling (ASL) MRI can predict cerebral hyperperfusion after carotid endarterectomy (CEA) in patients with carotid stenosis. METHODS: Consecutive patients with carotid stenosis who underwent CEA between May 2015 and July 2021 were included. For each patient, a cerebral blood flow ratio (rCBF) map was obtained by dividing postoperative CBF with preoperative CBF images from two pseudo-continuous ASL scans. Hyperperfusion regions with rCBF > 2 were extracted and weighted with rCBF to calculate the hyperperfusion index. According to the distribution of the hyperperfusion index, patients were divided into hyperperfusion and non-hyperperfusion groups. Preoperative ASL images were scored based on the presence of arterial transit artifacts (ATAs) in 10 regions of interest corresponding to the Alberta Stroke Programme Early Computed Tomography Score methodology. The degree of stenosis and primary and secondary collaterals were evaluated to correlate with the ASL score. Logistic regression and receiver operating characteristic curve analyses were performed to assess the predictive ability of the ASL score for cerebral hyperperfusion. RESULTS: Of 86 patients included, cerebral hyperperfusion was present in 17 (19.8%) patients. Carotid near occlusion, opening of posterior communicating arteries with incomplete anterior semicircle, and leptomeningeal collaterals were associated with lower ASL scores (p < 0.05). The preoperative ASL score was an independent predictor of cerebral hyperperfusion (OR = 0.48 [95% CI [0.33-0.71]], p < 0.001) with the optimal cutoff value of 25 points (AUC = 0.98, 94.1% sensitivity, 88.4% specificity). CONCLUSIONS: Based on the presence of ATAs, ASL can non-invasively predict cerebral hyperperfusion after CEA in patients with carotid stenosis. KEY POINTS: • Carotid near occlusion, opening of posterior communicating arteries with incomplete anterior semicircle, and leptomeningeal collaterals were associated with lower ASL scores. • The ASL score performed better than the degree of stenosis, type of CoW, and leptomeningeal collaterals, as well as the combination of the three factors for the prediction of cerebral hyperperfusion. • For patients with carotid stenosis, preoperative ASL can non-invasively identify patients at high risk of cerebral hyperperfusion after carotid endarterectomy without complex post-processing steps.

Relationship between cerebral hyperperfusion syndrome and the immediate change of cerebral blood flow after carotid artery stenting evaluated by single-photon emission computed tomography.

PURPOSE: Cerebral hyperperfusion syndrome (CHS) is a critical complication after carotid artery stenting (CAS). However, few CAS studies have evaluated immediate and temporary changes in ipsilateral cerebral blood flow (CBF) quantitatively. The study was performed to evaluate immediate changes in CBF after CAS and subsequent CBF changes in patients with cerebral hyperperfusion (HP) using 123I-IMP SPECT. METHODS: The subjects were 223 patients with chronic extracranial carotid artery stenosis who underwent CAS in our department between March 2010 and March 2020. Quantitative CBF and cerebrovascular reactivity to acetazolamide in the middle cerebral artery were assessed before CAS by 123I-IMP SPECT. CBF was also measured immediately after CAS by 123I-IMP SPECT. When HP was detected, CBF was measured again 3 and 7 days after CAS. RESULTS: The median (interquartile range) ipsilateral quantitative CBF change after CAS was - 0.1% (- 9.5-8.2%), and the upper value of the 95% CI of the quantitative CBF change was 48.2%. Thus, we defined HP after CAS as an increase in quantitative CBF of > 48.2% compared with the preoperative value. Of 223 patients, 5 (2.2%) had HP, and 4 of these patients (80%) developed CHS. In the CHS patients, HP was maintained for about 3 days and improved after about 7 days. CONCLUSION: An immediate CBF increase of > 48.2% after CAS may lead to development of CHS. In CHS after CAS, HP persisted for about 1 week and postoperative management may be required for at least 1 week.

Perioperative functional imaging after extracranial carotid endarterectomy for the detection of cerebral hyperperfusion syndrome.

INTRODUCTION: SyngoDynaPBVNeuro® is a tool to perform cerebral blood volume (CBV) measurements intraoperatively by functional imaging producing CT-like images. Aim of this prospective study was to analyze the clinical relevance and benefit of CBV measurement with regard to neurological complications like cerebral hyperfusion syndrome (CHS). METHODS: Forty-five patients undergoing endarterectomy (CEA) of the internal carotid artery were included; functional imaging with CBV measurement was performed before and after CEA. To evaluate and analyze CBV, six regions of interest (ROI) were identified for all patients with an additional ROI in patients with symptomatic ICA stenosis and previous stroke. The primary endpoint of the study was a perioperative change in CBV measurements. Secondary outcomes were incidence of stroke, TIA, CHS, and perioperative morbidity and mortality. RESULTS: Thirty-day stroke incidence and thirty-day mortality were 0%. Thirty-day morbidity was 6.7%. Two patients from the asymptomatic group suffered from transient neurological symptoms without signs of intracerebral infarction in CT or MR scan, meeting diagnostic criteria for CHS. In 83.3% of ROIs in these patients, an increase of blood volume was detected. Overall, 26.7% patients suffered from unilateral headache as expression of potential CHS. A total of 69.4% of ROIs in patients with postoperative unilateral headache showed an increase when comparing pre- and postoperative CBV measurements. CONCLUSION: The results show that increased CBV measured by functional imaging is a possible surrogate marker of neurological complications like CHS after CEA. By using intraoperative CBV measurement, the risk of CHS can be estimated early and appropriate therapeutic measures can be applied.

Moyamoya Disease-Standards and Advances in Revascularization Procedure and Peri-operative Management.

Moyamoya disease (MMD) is a chronic, occlusive cerebrovascular disease with unknown etiology characterized by progressive stenosis at the terminal portion of the internal carotid artery and the abnormal vascular network formation at the base of the brain. Superficial temporal artery-middle cerebral artery (STA-MCA) bypass is a preferred surgical procedure for ischemic-onset MMD patients by improving cerebral blood flow. Recent evidence further indicates that flow-augmentation bypass has a potential role for preventing re-bleeding in hemorrhagic-onset MMD patients. Based on such cumulative evidence, there is a worldwide increase in the number of MMD patients undergoing bypass surgery, thus thorough understanding of the basic pathology of MMD including peri-operative hemodynamics is critical for avoiding surgical complications. The author sought to demonstrate the standard surgical procedure of STA-MCA bypass with indirect pial synangiosis for adult MMD patients and its pitfall in the early postoperative period, introducing the characteristic peri-operative hemodynamic condition of adult MMD after surgery, such as local cerebral hyperperfusion and intrinsic hemodynamic ischemia caused by watershed shift phenomenon.

Effect of breath-hold on the responses of arterial blood pressure and cerebral blood velocity to isometric exercise.

PURPOSE: The present study examined the effect of breath-hold without a Valsalva maneuver during isometric exercise on arterial blood pressure (ABP) and cerebral blood flow (CBF). METHODS: Twenty healthy adults (15 men and five women) randomly performed only breath-hold without a Valsalva maneuver (BH), and an isometric handgrip exercise for 30 s at 40% of individual maximal voluntary contraction with continuous breathing (IHG) and with breath-hold without the Valsalva maneuver (IHG-BH). Mean ABP (MAP) and blood velocity in the middle (MCA Vmean) and posterior cerebral arteries (PCA Vmean) were continuously measured throughout each protocol. RESULTS: MAP was elevated during the IHG-BH compared with IHG (P < 0.001) and BH (P = 0.001). Similarly, both MCA Vmean and PCA Vmean were higher during IHG-BH compared with IHG and BH (all P < 0.001). Moreover, the relative change in MAP from the baseline was correlated with that in both cerebral blood velocities during the BH (MCA Vmean: r = 0.739, P < 0.001 and PCA Vmean: r = 0.570, P = 0.009) and IHG-BH (MCA Vmean: r = 0.755, P < 0.001 and PCA Vmean: r = 0.617, P = 0.003) condition, but not the IHG condition (P = 0.154 and P = 0.306). CONCLUSION: These results indicate that during isometric exercise, a breath-hold enhances an exercise-induced increase in MAP and, consequently, MCA Vmean and PCA Vmean.

A Case of Intracranial Vertebral Artery Stenosis Treated with Percutaneous Transluminal Angioplasty and Stenting Guided by Brain Oximetry.

Surgical treatment should be considered for patients with severe vertebrobasilar artery (VBA) stenosis or progressive symptoms, but there is currently no clear treatment algorithm. We report a case of symptomatic intracranial vertebral artery stenosis with repeated cerebral infarction treated by percutaneous transluminal angioplasty (PTA) and stenting and monitoring of oxygen saturation by a brain oximeter. The patient was a 76-year-old man referred to our hospital due to infarction in the right cerebellum. Angiography showed 60% stenosis in the right vertebral artery and 90% stenosis in the left vertebral artery with progressive stenosis in the left. The patient was treated with intravenous and oral triple antiplatelet therapy but had dizziness again with new cerebral infarctions in the left cerebellum and right pontine. We shaved the patient's hair up to the superior nuchal line and placed left and right oximeter probes on each cerebellar hemisphere (2 cm lateral and 2 cm caudal from the external occipital protuberance). Under evaluation of blood flow in the posterior circulation with INVOS Cerebral/Somatic Oximeter, PTA and stent placement were performed for left vertebral artery stenosis. Postoperatively, the dizziness disappeared, and the patient was discharged on his own with good outcome. He has not had a recurrent stroke in over 6 years. Although medical treatment is generally considered the first choice for VBA stenosis, recurrent cerebral infarction occurs at a high rate in symptomatic lesions, and the prognosis is poor. In addition, the perioperative complication rate is not low, and there is no established method for evaluating perfusion of posterior circulation. The brain oximeter is already known to be useful in carotid artery (CA) revascularisation. In this report, we were able to perform a minimally invasive evaluation of blood flow in the posterior circulation using the brain oximeter which might be useful for surgical revascularisation not only in CA but also in VBA.

Isolated left common carotid artery: multidisciplinary management is the key to success.

An isolated carotid artery is a rare aortic arch anomaly. Instead of connecting to the aorta, the isolated carotid artery connects anomalously to the pulmonary artery. Chronically altered cerebral circulation poses the risk of cerebral hyperaemia following surgical reimplantation. We describe successful reimplantation of the isolated left common carotid artery in a child, highlighting the importance of a multidisciplinary approach for good clinical and neurological outcomes. We also briefly discuss the embryologic basis of this rare arch anomaly.

De Novo Cerebral Microbleeds and Cognitive Decline in Cerebral Hyperperfusion After Direct Revascularization for Adult Moyamoya Disease.

OBJECTIVES: Adult patients with moyamoya disease (MMD) occasionally develop cognitive decline due to cerebral hyperperfusion following direct revascularization surgery. However, how the hyperperfusion phenomenon contributes to declines in cognitive function remains unclear. The present supplementary analysis of a prospective study aimed to determine whether cerebral hyperperfusion following direct revascularization surgery for adult MMD with ischemic presentation and misery perfusion leads to development of de novo cerebral microbleeds (CMBs) and whether postoperative cognitive decline is related to these CMBs. MATERIALS AND METHODS: In total, 32 patients who underwent direct revascularization surgery also underwent T2*-weighted magnetic resonance imaging (T2*WI) and neuropsychological testing before and 2 months after surgery. Development of cerebral hyperperfusion and hyperperfusion syndrome following surgery was defined based on brain perfusion single-photon emission computed tomography (SPECT) findings and clinical symptoms. RESULTS: Cerebral hyperperfusion on brain perfusion SPECT (95% confidence interval [CI], 1.1-10.8; p = 0.0175) or cerebral hyperperfusion syndrome (95%CI, 1.3-15.3; p = 0.0029) was significantly associated with postoperatively increased CMBs on T2*WI. Postoperatively increased CMBs were significantly associated with postoperative cognitive decline (95%CI, 1.8-20.4, p = 0.0041). For patients with cerebral hyperperfusion on brain perfusion SPECT, the incidence of postoperative cognitive decline was significantly greater in patients with than in those without postoperatively increased CMBs (p = 0.0294). CONCLUSIONS: Cerebral hyperperfusion following direct revascularization surgery for adult MMD with ischemic presentation and misery perfusion contributes to the development of de novo CMBs and postoperative cognitive decline is related to these CMBs.

Transcranial Doppler 6 h after Successful Reperfusion as a Predictor of Infarct Volume.

OBJECTIVES: The aim of the study is to analyze the hemodynamic changes in the middle cerebral artery (MCA) after endovascular revascularization in acute ischemic stroke (AIS) due to large vessel occlusion and its association with the infarct volume size in the control head CT. MATERIALS AND METHODS: Prospective study of patients with AIS due to internal carotid artery terminus or M1 segment of the MCA occlusion, who underwent endovascular treatment with a final TICI 2b-3 score, without concomitant stenosis ≥50% in both cervical carotid arteries. Transcranial Doppler ultrasound (TCD) of both MCAs was carried out at 6 h after the endovascular procedure. Mean flow velocities (MFV) after arterial reperfusion and its association with the infarct volume size in 24-36 h control head CT were determined. RESULTS: 91 patients (51 women) were included with a median age of 78 years and National institute of Health Stroke Scale of 18. The MCA was occluded in 76.92%, and intravenous thrombolysis was administered in 40.7%. The incidence of symptomatic intracranial hemorrhage was 5.5%. At three months, mortality was 19.8% and a 52.7% of patients achieved functional independence (modified Rankin Scale 0-2). After a multivariable logistic regression analysis, an increase in the MFV greater than 50% at 6 h in the treated MCA compared to contralateral MCA, was an independent predictor of large infarct volume in the control head CT with an OR 9.615 (95%CI: 1.908-47.620), p=0.006 CONCLUSIONS: Increased MFV assessed by TCD examination following endovascular recanalization is independently associated with larger infarct volume.

A Novel Hyperspectral Imaging System for Intraoperative Prediction of Cerebral Hyperperfusion Syndrome after Superficial Temporal Artery-Middle Cerebral Artery Anastomosis in Patients with Moyamoya Disease.

BACKGROUND: Postoperative cerebral hyperperfusion syndrome (CHS) may occur after superficial temporal artery (STA)-middle cerebral artery (MCA) bypass for moyamoya disease (MMD). Predicting postoperative CHS is challenging; however, we previously reported the feasibility of using a hyperspectral camera (HSC) for monitoring intraoperative changes in brain surface hemodynamics during STA-MCA bypass. OBJECTIVE: To investigate the utility of HSC to predict postoperative CHS during STA-MCA bypass for patients with MMD. METHODS: Hyperspectral images of the cerebral cortex of 29 patients with MMD who underwent STA-MCA bypass were acquired by using an HSC before and after anastomosis. We then analyzed the changes in oxygen saturation after anastomosis and assessed its correlation with CHS. RESULTS: Five patients experienced transient neurological deterioration several days after surgery. 123I-N-Isopropyl-iodoamphetamine single-photon emission computed tomography scan results revealed an intense, focal increase in cerebral blood flow at the site of anastomosis without any cerebral infarction. Patients with CHS showed significantly increased oxygen saturation (SO2) in the cerebral cortex after anastomosis relative to those without CHS (33 ± 28 vs. 8 ± 14%, p < 0.0001). Receiver operating characteristic analysis results show that postoperative CHS likely occurs when the increase rate of cortical SO2 value is >15% (sensitivity, 85.0%; specificity, 81.3%; area under curve, 0.871). CONCLUSIONS: This study indicates that hyperspectral imaging of the cerebral cortex may be used to predict postoperative CHS in patients with MMD undergoing STA-MCA bypass.

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

PURPOSE: 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. METHODS: 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 1-7 days 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). RESULTS: 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%. CONCLUSION: 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.

Pre-operative higher hematocrit and lower total protein levels are independent risk factors for cerebral hyperperfusion syndrome after superficial temporal artery-middle cerebral artery anastomosis with pial synangiosis in adult moyamoya disease patients-case-control study.

Superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis is a standard treatment for adult moyamoya disease (MMD) patients. Cerebral hyperperfusion (CHP) syndrome is one of the most serious complications of this procedure that can result in deleterious outcomes, but predicting CHP before revascularization surgery remains challenging. Furthermore, the hematological/serological factors associated with CHP syndrome are unknown. To investigate the correlation between pre-operative hematological/serological factors and the development of CHP syndrome after STA-MCA anastomosis with encephalo-duro-myo-synangiosis (EDMS) for MMD., a pre-operative peripheral blood test was performed within 5 days before surgery. Local cerebral blood flow (CBF) at the site of anastomosis was quantified by N-isopropyl-p-[123I] iodoamphetamine single-photon emission computed tomography 1 and 7 days after surgery, and the pre-operative CBF value at the corresponding area was measured. We defined CHP syndrome as a local CBF increase over 150% compared with the pre-operative value, which was responsible for delayed intracranial hemorrhage, transient focal neurological deterioration, and/or seizure. Then, we retrospectively investigated the correlation between peripheral blood test results and the development of CHP syndrome. CHP syndrome 1 day after STA-MCA anastomosis with EDMS was observed in nine patients (9/114 hemispheres; 7.9%). Multivariate analysis with multiple imputation revealed that higher hematocrit value and lower total protein level were significantly associated with the development of CHP syndrome (p value: 0.028 and 0.043, respectively). Higher pre-operative hematocrit levels and lower pre-operative total protein levels are novel risk factors for CHP syndrome after direct revascularization surgery in adult MMD patients.

Near-Infrared Spectroscopy Might Help Prevent Onset of Cerebral Hyperperfusion Syndrome.

Cerebral hyperperfusion syndrome (CHS) is a rare but fatal perioperative complication after surgical correction of carotid stenosis. Despite numerous treatment options for preventing CHS, it does occur in some patients. We developed the outlet gate technique (OGT), in which the embolic balloon was deflated gradually in accordance with the ratio of oxygen saturation measured by a brain oximeter of the ipsilateral brain region to that in the contralateral region. Between June 2017 and May 2018, 39 patients with carotid stenosis underwent endovascular carotid revascularization procedures; of these, 20 underwent the procedure with the OGT. CBO was measured five times in those 20 patients: before the procedure, with the embolic protection device (EPD) on, with the EPD off, during the procedure, and after the procedure. Preventive treatment options were used more frequently in these patients, and although their surgical status seemed more complicated, perioperative complications were not increased. There were almost significant differences between CBO values except between those during and after the procedure with the OGT. This showed that the OGT allowed for stabilization of the CBO and thus has the potential to prevent CHS.

Intraoperative transit-time ultrasonography combined with FLOW800 predicts the occurrence of cerebral hyperperfusion syndrome after direct revascularization of Moyamoya disease: a preliminary study.

BACKGROUND: Cerebral hyperperfusion syndrome (CHS) is a common complication after direct bypass surgery in patients with Moyamoya disease (MMD). Since preventive measures may be inadequate, we assessed whether the blood flow difference between the superficial temporal artery (STA) and recipient vessels (△BF) and the direct perfusion range (DPR) are related to CHS. METHODS: We measured blood flow in the STA and recipient blood vessels before bypass surgery by transit-time probe to calculate △BF. Perfusion changes around the anastomosis before and after bypass were analyzed with FLOW800 to obtain DPR. Multiple factors, such as △BF, DPR, and postoperative CHS, were analyzed using binary logistic regression. RESULTS: Forty-one patients with MMD who underwent direct bypass surgery were included in the study. Postoperative CHS symptoms occurred in 13/41 patients. △BF and DPR significantly differed between the CHS and non-CHS groups. The optimal receiver operating characteristic (ROC) curve cut-off value was 31.4 ml/min for ΔBF, and the area under the ROC curve (AUC) was 0.695 (sensitivity 0.846, specificity 0.500). The optimal cut-off value was 3.5 cm for DPR, and the AUC was 0.702 (sensitivity 0.615, specificity 0.750). CONCLUSION: Postoperative CHS is caused by multiple factors. △BF is a risk factor for CHS while DPR is a protective factor against CHS.

Solitaire stents deployment may reduce ischemic events in staged angioplasty for severe carotid stenosis.

OBJECTIVES: Cerebral hyperperfusion syndrome is a fatal complication that can occur after stent angioplasty in patients with severe carotid artery stenosis. Staged angioplasty can prevent cerebral hyperperfusion syndrome. Conventional staged angioplasty consists of small balloon angioplasty in the first stage and carotid artery stenting in the second stage two to four weeks later. Sometimes, antegrade flow during stage 1 could hardly be maintained and stent will be needed. Solitaire stents were used in some patients in our center. This study aimed to examine the safety and effectiveness of Solitaire stents in staged angioplasty. METHODS: A retrospective analysis was performed on patients with severe carotid artery stenosis and preoperative computed tomography perfusion indicating risk of cerebral hyperperfusion syndrome from 2011 to 2018. Small balloon angioplasty (<3 mm in diameter) only was performed in stage 1 (group 1). If antegrade flow during stage 1 is compromised, then a solitaire stent is deployed (group 2). After two to four weeks, cerebral angiography was undertaken in both groups to determine whether to perform stage 2. If the residual stenosis was more than 50%, carotid artery stenting was deployed. Angiographic results, clinical results, and follow-up results were collected and analyzed. RESULTS: Twenty-five patients were included in the study (group 1, n = 19; group 2, n = 6). After stage 1, no patient in group 2 and two patients in group 1 developed new symptomatic cerebral infarction (0.0% vs. 10.5%, p = 1.000). One patient in group 2 and three patients in group 1 (16.7% vs. 15.8%, p = 1.000) developed symptomatic cerebral hyperperfusion syndrome. One patient in group 2 (n = 4) and three patients in group 1 (n = 12) (25% vs. 25%, p = 1.000) developed hyperperfusion phenomenon. Two patients in group 2 and five patients in group 1 (33.3% vs. 26.3%, p = 1.000) developed symptomatic cerebral hyperperfusion syndrome or hyperperfusion phenomenon. One patient in group 1 developed symptomatic cerebral hyperperfusion syndrome and hyperperfusion phenomenon. After stage 2, no new cerebral infarction occurred in both groups. No patient in group 2 (n = 3) and one patient in group 1 (n = 17) developed symptomatic cerebral hyperperfusion syndrome (0.0% vs. 5.9%, p = 1.000). In the combined analysis of both stages, two patients (10.5%) developed new symptomatic cerebral infarction and four patients (21.1%) developed symptomatic cerebral hyperperfusion syndrome in group 1, no patient (0.0%) developed symptomatic cerebral infarction and one patient (16.7%) developed symptomatic cerebral hyperperfusion syndrome in group 2. There was no significant difference in symptomatic cerebral infarction and symptomatic cerebral hyperperfusion syndrome between the two groups (p = 1.000; p = 1.000). Three patients in group 2 and 17 patients in group 1 (50% vs. 89.5%, p = 0.070) underwent stage 2 angioplasty. No cerebral hemorrhage or cerebral infarction occurred in the Solitaire group during the one-year follow-up period. CONCLUSIONS: Solitaire stents deployment may reduce ischemic events in staged angioplasty for severe carotid stenosis.

Bilateral Cerebral Hyperperfusion Syndrome Following Carotid Artery Stenting in Stroke - A Case Report.

BACKGROUND: Revascularization of the symptomatic carotid artery is performed with endarterectomy or stenting. Rarely, patients may develop cerebral hyperperfusion syndrome (CHS) following revascularization. This usually occurs in the cerebral hemisphere ipsilateral to revascularized carotid stenosis. CHS rarely involves the contralateral hemisphere. OBJECTIVE: To present a case of CHS involving bilateral cerebral hemispheres following carotid artery stenting in acute ischemic stroke. CASE DESCRIPTION: A 66-year-old woman presented with right side weakness and aphasia. National Institutes of Health stroke scale score was 27. CT angiogram/perfusion showed high grade left internal carotid artery (ICA) stenosis, left middle cerebral artery (MCA) occlusion, and increased time to peak in left MCA territory. She underwent mechanical thrombectomy with complete reperfusion. Left carotid artery stenting was performed for 85% cervical ICA stenosis with thrombus. She neurologically deteriorated and required intubation after the procedure. Follow-up CT perfusion at 18 hours after thrombectomy showed increased cerebral blood flow and early time to peak in bilateral MCA territories. CT head showed parenchymal hematoma in the left subcortical area with extension to the ventricle. Fluid-attenuated inversion recovery MRI on day 4 showed diffuse white matter hyperintensities in the entire right hemisphere, and left temporal and frontal lobes suggestive of vasogenic edema. CONCLUSION: This case highlights bilateral cerebral hyperperfusion syndrome characterized by neurological worsening, imaging findings of parenchymal hemorrhage, vasogenic edema and increased cerebral blood flow without any new ischemic lesions. The involvement of bilateral hemispheres in the absence of significant contralateral carotid stenosis is unique in this case.