Hyperperfusion Syndrome Research Articles

Cerebral hyper perfusion syndrome after carotid artery stenting

To explore the risk factors, clinical characteristics, precaution and treatment of hyper perfusion syndrome (HPS) after carotid artery stenting (CAS). From September 2014 to March 2018, the clinical data of 226 patients with severe carotid stenosis (70%-99%) treated with carotid artery stenting (CAS)at Department of Interventional Radiology and Vascular Surgery, Peking University Third Hospital, were analyzed retrospectively．Five of them developed HPS after CAS．The relationship between the clinical baseline data, imaging characteristics, perioperative management and HPS were assessed. In this group, 5 patients of them (2.21%, 5/226) developed HPS after CAS, and 2 patients of them (0.88%, 2/226) were hyper perfusion induced intracranial hemorrhage (HICH). The 5 patients consisted of 4 men and 1 woman whose age ranged from 58 to 74 years. The symptoms of HPS occurred within 4 hours to 3 days after CAS. Among the 5 cases, the clinical manifestations were that 2 cases with headache, 1 case with delirium,1 case with hemiparesis of left limbs, and 1 case with coma(died ultimately).The main manifestations of case 1 and case 2 were headache in the frontal parietal temporal region of the operative side, accompanied by nausea and vomiting. The symptoms were relieved after blood pressure lowering treatment and mannitol dehydration. The main manifestations of case 3 were excitement and delirium. The symptoms were relieved by a small dose of sedatives, also with blood pressure lowering treatment and mannitol dehydration. The initial symptoms of case 4 were excitement and delirium, accompanied by mild headache of the operative side, and hemiplegia of the contralateral limb occurred within a short time. The main manifestation of case 5 was severe headache and went into deep coma within a short time. This patient died of massive cerebral hemorrhage ultimately. HPS is an uncommon but serious complication after CAS. Improving our understanding and heightening vigilance of HPS is necessary. The earlier diagnosis, the earlier treatment.

Sentinel Angiographic Signs of Cerebral Hyperperfusion after Angioplasty and Stenting of Intracranial Atherosclerotic Stenosis: A Technical Note.

Cerebral hyperperfusion syndrome is a serious complication of endovascular angioplasty and stent placement for long-standing intracranial stenosis, resulting in neurologic dysfunction, seizure, or reperfusion hemorrhage. Rigorous control of blood pressure is commonly used in the perioperative period to prevent cerebral hyperperfusion syndrome, but the optimal blood pressure is often arbitrary. We describe the angiographic features that reflect impaired cerebral autoregulation and microvascular transit abnormality, which may be used to gauge the optimal blood pressure parameters in the immediate postintervention period for prevention of cerebral hyperperfusion syndrome.

Transcranial Doppler 24 Hours after Carotid Endarterectomy Accurately Identifies Patients Not at Risk of Cerebral Hyperperfusion Syndrome

Intra-operative transcranial Doppler (TCD) is the gold standard for prediction of cerebral hyperperfusion syndrome (CHS) in patients after carotid endarterectomy (CEA) under general anaesthesia. However, post-operative cerebral perfusion patterns may result in a shift in risk assessment for CHS. This is a study of the predictive value of additional post-operative TCD measurements for prediction of CHS after CEA. This was a retrospective analysis of prospectively collected data in patients undergoing CEA with available intra- and post-operative TCD measurements between 2011 and 2016. The mean blood flow velocity in the middle cerebral artery (MCAVmean) was measured pre-operatively, intra-operatively, and post-operatively at two and 24h. Intra-operative MCAVmean increase was compared with MCAVmean increase two and 24h post-operatively in relation to CHS. Cerebral hyperperfusion (CH) was defined as MCAVmean increase≥100%, and CHS as CH with the presence of headache or neurological symptoms. Positive (PPV) and negative predictive values (NPV) of TCD measurements were calculated to predict CHS. Of 257 CEA patients, 25 (9.7%) had CH intra-operatively, 45 (17.5%) 2h post-operatively, and 34 (13.2%) 24h post-operatively. Of nine patients (3.5%) who developed CHS, intra-operative CH was diagnosed in two and post-operative CH in eight (after 2h [n=5] or after 24h [n=6]). This resulted in a PPV of 8%, 11%, and 18%, and a NPV of 97%, 98%, and 99% for intra-operative, 2h and 24h post-operative TCD, respectively. TCD measurement of the MCAVmean 24h after CEA under general anaesthesia is most accurate to identify patients who are not at risk of CHS.

Four-Dimensional Flow MRI Analysis of Cerebral Blood Flow Before and After High-Flow Extracranial–Intracranial Bypass Surgery With Internal Carotid Artery Ligation

The hemodynamic changes that occur after high-flow (extracranial-intracranial) EC-IC bypass surgery with internal carotid artery (ICA) ligation are not well known. To assess blood flow changes after high-flow EC-IC bypass with ICA ligation by time-resolved 3-dimensional phase-contrast (4D Flow) magnetic resonance imaging (MRI). We enrolled 11 patients who underwent high-flow EC-IC bypass. 4D Flow MRI was performed before and after surgery to quantify the blood flow volume (BFV) of the ipsilateral ICA (BFViICA), bypass artery (BFVbypass), contralateral ICA (BFVcICA), and basilar artery (BFVBA). Subsequently, we calculated the total BFV (BFVtotal=BFViICA+BFVcICA+BFVBA [before surgery], BFVcICA+BFVBA+BFVbypass [after surgery]). The BFV changes after bypass was statistically analyzed. BFVbypass was slightly lower than BFViICA, but the difference was not statistically significant (3.84±0.94 vs 4.42±1.38 mL/s). The BFVcICA and BFVBA significantly increased after bypass surgery (BFVcICA 5.89±1.44 vs 7.22±1.37 mL/s [P=.0018], BFVBA 3.06±0.41 vs 4.12±0.38 mL/s [P<.001]). The BFVtotal significantly increased after surgery (13.37±2.58 vs 15.18±1.77 mL/s [P=.015]). There was no evidence of hyperperfusion syndrome in any cases. After high-flow EC-IC bypass with permanent ICA ligation, the bypass artery could partially compensate for the loss of BFV of the sacrificed ICA. The increased flow of the contralateral ICA and BA supply collateral blood flow. Clinically irrelevant hyperperfusion was observed.

Treatment Strategy for Progressive Cervical Internal Carotid Artery Stenosis Under Restriction of the Use of Antiplatelet Drugs

Acute ischemic stroke caused by cervical internal carotid artery stenosis (ICS) with altered consciousness and progressive paralysis leads to a poor neurologic prognosis. When such a patient is brought to the hospital in the hyperacute phase, intravenous tissue plasminogen activator is first administered. However, when an indwelling carotid artery stent is required after administration, physicians often hesitate to use antithrombotic drugs. In this report, we propose performing staged angioplasty (SAP) for such cases. Four patients were retrospectively investigated. In all 4 patients, we immediately performed only percutaneous transluminal angioplasty (PTA) without antiplatelet drugs. If both cerebral perfusion on angiography and neurologic findings improved, no additional treatment was provided; otherwise, emergency carotid artery stenting (eCAS) was performed. In PTA-successful cases, eCAS or carotid endarterectomy (CEA) was performed with single or dual antiplatelet drugs at a later date. The success rate of PTA was 50% (2 of 4), and the overall treatment success rate was 100% (4 of 4). Three patients had favorable outcomes (modified Rankin Scale [mRS] score 0-2), but unfortunately, 1 patient had severe disability (mRS score >3) on discharge. The PTA-successful patients had no perioperative complications. On the other hand, 1 of the 2 patients who underwent eCAS experienced embolic complications, including distal embolization. In this investigation, both eCAS and SAP could be performed safety. However, performing SAP first without antiplatelet drugs to avoid hemorrhagic complications and cerebral hyperperfusion syndrome appears to have considerable validity.

Microbleeds after Carotid Artery Stenting: Small Embolism May Induce Cerebral Microbleeds

Background: Since the advent of magnetic resonance imaging technology, cerebral microbleeds can be diagnosed in vivo. However, the underlying mechanism of cerebral microbleed formation is not fully understood. Objectives: This study aimed to identify the factors associated with cerebral microbleeds after carotid artery stenting (CAS). Method: We retrospectively examined 125 patients who underwent CAS for carotid stenosis. Cerebral microbleeds were investigated using T2*-weighted gradient-echo (GRE) imaging before and after CAS. We analyzed the possible association of new microbleeds with the following risk factors: the number of baseline microbleeds and ischemic cerebral lesions, the occurrence of cerebral hyperperfusion syndrome, and new ischemic cerebral lesions after CAS. Results: Baseline cerebral microbleeds were detected in 53 patients (42.4%). New cerebral microbleeds after CAS were observed in 13 of 125 patients (10.4%) and were exclusively associated with new ischemic lesions but not with other risk factors. No patient showed a merged image of a new cerebral microbleed on GRE imaging or a new ischemic lesion on diffusion-weighted imaging. Lobar and deep microbleeds were noted in 12/13 (92.3%) and 1 patient (7.7%), respectively. Of 12 patients with new microbleeds, 10 (76.9%) and 2 (15.4%) had a new microbleed in the ipsilateral and contralateral hemispheres, respectively. Conclusions: We found that new cerebral microbleeds developed after CAS and that these might be associated with new ischemic lesions, mostly in the territory of the treated carotid artery. We speculate that these microbleeds result from the deoxygenation of hemoglobin in the embolus or, alternatively, small hemorrhagic transformation of ischemic lesions.

Endovascular treatment of a patient with multifocal occlusal-stenotic lesion of the head main arteries using a modified anchor stenting technique and confirming the efficacy and adequacy of treatment by controlling changes in cerebral hemoperfusion

A case of treating of 59 years old patient with a multifocal occlusive and stenotic lesion of the main arteries of the head is described. Patients has occlusions of both internal carotid arteries, left external carotid artery, right vertebral artery, severe stenosis in the initial segment of the left subclavian artery and severe stenosis in the ostium of the left vertebral artery, with cognitive impairment and coordination disorders.A single-session stenting of the stenosis in the ostium of left vertebral artery with balloon-expan-dable elution-stent with usage of the modified Szabo anchor technique and stenting of the stenosis in the initial segment of the subclavian artery with a balloon-expandable peripheral stent was performed. Stenoses are eliminated, all cerebral arteries of the vertebrobasilar basin and both carotid basins are supplied by the left vertebral artery.After 50 days, the patient’s neurological status was assessed and a computed tomographic perfusiography of the brain was performed. The cognitive status improved significantly (initially – 23 points on the MoCA scale, after the operation – 27 points), coordination disorders regressed. According to computed tomographic brain perfusion, there are increase in CBF (cerebral blood flow) above normal in all areas except for the area of ​​stroke; an increase in CBV (cerebral blood volume) above normal, which is a reflection of arterioles vasodilation; increase in MTT (mean transit time) in all zones, which is a sign of collateral blood flow. Based on these data, it was concluded that further revascularization operations on the occluded cerebral arterial basins can lead to the hyperperfusion syndrome clinical manifestation. The performed endovascular stage of treatment was effective and sufficient to significantly improve the patient’s neurological and cognitive status and prevent the development of recurrent ischemic stroke.

PC056. Quality Improvement in Timing and Delivery of Carotid Endarterectomies at the Ottawa Hospital: Is the Pendulum Swinging Too Far?

Quality improvement initiatives at The Ottawa Hospital (TOH) have aimed to reduce time between symptom onset and carotid endarterectomy (CEA) delivery; however, recent evidence suggests that perioperative stroke risk may be higher in the hyperacute setting (<48 hours from symptom onset). The study objective was to identify factors—such as timing—that are associated with adverse outcomes after CEA. This is a cohort study of patients receiving CEA by vascular surgeons at TOH between 2003 and 2018. Clinical and ultrasound surveillance data were obtained from electronic medical records (vOACIS; Telus Health, Montreal, Quebec, Canada) and TOH’s ultrasound database (VascuBase; Consensus Medical Systems, Richmond, BC, Canada). Patients’ demographics, timing and perioperative data, and postoperative complications and restenosis rates were recorded. Adverse outcomes were stratified by six variables: age, timing from symptom onset to surgery, anesthetic, operative technique, preoperative stenosis, and symptomatic status. Statistical analyses were performed to determine which variables were associated with higher rates of adverse outcomes using χ2 and Fisher exact tests. During the study period, 1190 CEAs were performed in 1129 patients. The majority were symptomatic (78.0%), with stenosis ranging from 70% to 99% (93.3%), and received patch arterioplasty (83.6%), without a shunt (84.9%), under regional anesthetic (88.3%). Overall 30-day stroke, stroke/death, and stroke/death/myocardial infarction (MI) rates were 2.1%, 2.6%, and 2.8%. Hyperperfusion syndrome and nerve injury rates were 4.0% and 5.3% (Table). Among symptomatic patients, CEA was performed within 48 hours in 10.9%, 2 to 14 days in 34.8%, and >14 days in 54.2%. Rate of nerve injury was higher among asymptomatic patients than symptomatic (P = .044). When stratified by anesthetic, combined rate of stroke, death, and MI was highest among patients who received a general anesthetic (7.4% vs 2.3% [regional anesthetic] and 0.0% [local anesthetic]; P = .016). When stratified by timing, combined stroke, death, and MI was highest among patients who received CEA within 48 hours of symptom onset (P = .007). This signal was predominantly driven by the stroke rate, which was also highest among those who received CEA within 48 hours (Fig; P = .038). Eversion endarterectomy was associated with the highest rate of postoperative ipsilateral restenosis >80% (17.9% vs 3.6% [patch angioplasty] and 2.8% [primary repair]; P = .014). Neither preoperative ipsilateral stenosis nor age was associated with adverse outcomes. Despite improvement in CEA delivery for stroke prevention after symptom onset, there is an association between hyperacute CEA (<48 hours) and worse outcomes. Further investigation should determine whether this represents a higher risk population who will benefit from expedient surgery or whether a “cool-down” period is warranted.TableOverall short-term (30-day) outcomesOutcomeNo.Rate, %Stroke/TIA252.1Death60.5MI40.3Combined stroke + death292.6Combined stroke + death + MI312.8Nerve injury635.3Intracranial bleed40.3Hyperperfusion syndrome484.0MI, Myocardial infarction; TIA, transient ischemic attack.Nerve injury and hyperperfusion syndrome were the two most common adverse outcomes. Unit of analysis varied between carotid and patient, depending on the outcome observed. Open table in a new tab

Effectiveness of Staged Angioplasty for Avoidance of Cerebral Hyperperfusion Syndrome After Carotid Revascularization

A multicenter, retrospective review was performed from October 2007 to March 2014. During this period, 523 patients (8%) from 44 Japanese centers were considered at high risk of cerebral hyperperfusion syndrome by the findings from single-photon emission computed tomography (SPECT) or other studies. Of 530 atherosclerotic lesions, 428 were treated by single-stage carotid artery stenting (CAS) and 102 by carotid artery angioplasty using a 3-mm-diameter balloon, followed by delayed, or staged, CAS (SAP) 2 to 4 weeks later. The preoperative mean carotid artery stenosis and SPECT parameters were worse in the SAP group than in the single-stage CAS group. All cases were performed via the transfemoral approach and embolic protection devices. The rate of cerebral hyperperfusion syndrome was significantly less in the SAP group (4%) compared with the single-stage CAS group (10%; P = .47). Multivariate analysis showed that SAP was negatively related to hyperperfusion syndrome. The composite rate of transient ischemic attack and ischemic stroke was about the same in both groups (9%). Carotid angioplasty followed by staged CAS might be effective for preventing hyperperfusion syndrome.

In Reply to ”Cerebral Hyperperfusion Syndrome After Chronic Subdural Hematoma Drainage”

In Reply to ”Cerebral Hyperperfusion Syndrome After Chronic Subdural Hematoma Drainage”

Effects of Combined Remote Ischemic Pre-and Post-Conditioning on Neurologic Complications in Moyamoya Disease Patients Undergoing Superficial Temporal Artery-Middle Cerebral Artery Anastomosis.

Superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis is the most commonly used treatment for Moyamoya disease. During the perioperative period, however, these patients are vulnerable to ischemic injury or hyperperfusion syndrome. This study investigated the ability of combined remote ischemic pre-conditioning (RIPC) and remote ischemic post-conditioning (RIPostC) to reduce the occurrence of major neurologic complications in Moyamoya patients undergoing STA-MCA anastomosis. The 108 patients were randomly assigned to a RIPC with RIPostC group (n = 54) or a control group (n = 54). Patients in the RIPC with RIPostC group were treated with four cycles of 5-min ischemia and 5-min reperfusion before craniotomy and after STA-MCA anastomosis (RIPostC). The incidence of postoperative neurologic complications and the duration of hospital stay were determined. The overall incidence of neurologic complication was significantly higher in the control group than in the RIPC with RIPostC group (13 vs. 3, p = 0.013). The duration of hospital stay was significantly longer in the control group than in the RIPC with RIPostC group (17.8 (11.3) vs. 13.8 (5.9) days, p = 0.023). Combined remote ischemic pre- and post-conditioning can be effective in reducing neurologic complications and the duration of hospitalization in Moyamoya patients undergoing STA-MCA anastomosis.

Clinical Predictors of Hyperperfusion Syndrome Following Carotid Stenting: Results From a National Prospective Multicenter Study

ObjectivesThe aim of the HISPANIAS (HyperperfusIon Syndrome Post-carotid ANgIoplasty And Stenting) study was to define CHS rates and develop a clinical predictive model for cerebral hyperperfusion syndrome (CHS) after carotid artery stenting (CAS). BackgroundCHS is a severe complication following CAS. The presence of clinical manifestations is estimated on the basis of retrospective reviews and is still uncertain. MethodsThe HISPANIAS study was a national prospective multicenter study with 14 recruiting hospitals. CHS was classified as mild (headache only) and moderate-severe (seizure, impaired level of consciousness, or development of focal neurological signs). ResultsA total of 757 CAS procedures were performed. CHS occurred in 22 (2.9%) patients, in which 16 (2.1%) had moderate-severe CHS and 6 (0.8%) had mild CHS (only headache). The rate of hemorrhages was 0.7% and was associated with high mortality (20%). Pre-operative predictors of moderate-severe CHS in multivariate analysis were female sex (odds ratio [OR]: 3.24; 95% confidence interval [CI]: 1.11 to 9.47; p = 0.03), older patients (OR: 1.09; 95% CI: 1.01 to 1.17; p = 0.02), left carotid artery treated (OR: 4.13; 95% CI: 1.11 to 15.40; p = 0.03), and chronic renal failure (OR: 6.29; 95% CI: 1.75 to 22.57; p = 0.005). The area under the curve of this clinical and radiological model was 0.86 (95% CI: 0.81 to 0.92; p = 0.001). ConclusionsThe rate of CHS in the HISPANIAS study was 2.9%, with moderate-severe CHS of 2.1%. CHS was independently associated with female sex, older age, history of chronic kidney disease, and a treated left carotid artery. Although further investigations are needed, the authors propose a model to identify high-risk patients and develop strategies to decrease CHS morbidity and mortality in the future.

Phase-Contrast Magnetic Resonance Imaging Analysis of Cerebral Hyperperfusion Syndrome After Surgery in Adult Patients with Moyamoya Disease

To investigate potential risk factors for cerebral hyperperfusion syndrome (CHS) after surgery in patients with moyamoya disease (MMD) using phase-contrast magnetic resonance imaging (MRI). The study included 84 adult patients (89brain hemispheres) with MMD who underwent surgery. Preoperative phase-contrast MRI scans were performed for all patients. Peak velocity, average velocity, average flow, forward volume, and region of interest area of the bilateral internal and external carotid arteries, superficial temporal artery, and vertebral artery were calculated and analyzed. Patients were divided into CHS and non-CHS groups. Patients' age, sex, clinical symptoms, Suzuki stage, and MRI flow examination results were compared between the 2groups. Nineteen of 84 patients (89 hemispheres) with MMD were in the CHS group. Patients with ischemic onset symptoms were more likely to develop CHS after surgery (P< 0.05). There were no significant differences in age, sex, and Suzuki stage between the 2 groups. For surgery ipsilateral vessels, peak velocity, average flow and forward volume of superficial temporal artery and average flow of external carotid artery and region of interest area of internal carotid artery in the CHS group were significantly lower compared with the non-CHS group (P < 0.05). For surgery contralateral vessels, forward volume of superficial temporal artery and external carotid artery in the CHS group was significantly lower compared with the non-CHS group (P < 0.05). Patients with MMD and ischemic onset symptoms are more likely to develop CHS after surgery. Preoperative phase-contrast MRI analysis may be helpful to predict CHS in patients with MMD after surgery.

Asymmetric Cortical Vessel Sign Indicates Hemodynamic Deficits in Adult Patients with Moyamoya Disease

Asymmetric cortical vessel sign (ACVS) on susceptibility-weighted imaging (SWI) indicates elevated concentration of deoxyhemoglobin and elevated oxygen extraction fraction in patients with cerebral ischemia. This study aimed to clarify whether ACVS is associated with impaired hemodynamics and hyperperfusion syndrome in patients with moyamoya disease (MMD). Consecutive adult patients with MMD were enrolled. ACVS data on SWI and perfusion data using dynamic perfusion computed tomography were obtained and evaluated preoperatively and on postoperative days 2 and180. A total of 24 patients with MMD were enrolled. Of 11 (45.83%) patients showing positive ACVS before surgery, 8 turned negative on postoperative day 2 and 9 showed absence of ACVS 180 days after surgery. Regions of interest showing positive ACVS had lower cerebral blood flow (CBF, P<0.001), increased cerebral blood volume (P= 0.021), prolonged time to peak (P<0.001), and mean transit time (P= 0.009). No patients with hemorrhagic symptoms showed positive ACVS(P= 0.041) and patients with positive ACVS showed more increase in CBF (P<0.004). In patients with MMD, ACVS on SWI indicates severe impairment in hemodynamics and is associated with more increase in CBF after bypass surgery. Hence, ACVS on SWI might be considered as a neuroimaging marker for the evaluation of hemodynamics in patients with MMD.

Technical improvements in carotid revascularization based on the mechanism of procedural stroke.

The benefit of carotid revascularization in patients with severe carotid artery stenosis is hampered by the risk of stroke due to the intervention itself. The risk of periprocedural strokes is higher for carotid artery stenting (CAS) as compared to carotid endarterectomy (CEA). Over the past years, the pathophysiological mechanism responsible for periprocedural stroke seems to unfold step by step. Initially, all procedural strokes were thought to be the result of technical errors during surgical repair: cerebral ischemia due to clamping time of the carotid artery, cerebral embolization of atherosclerotic debris due to manipulation of the atheroma or thrombosis of the artery. Following improvements in surgical techniques, technical skills, new intraoperative monitoring technologies such as angioscopy, and the results of the first large clinical randomized controlled trials (RCT) it was believed that most periprocedural strokes were of thromboembolic nature, while a large part of these caused by technical error. Nowadays, analyses of underlying pathophysiological mechanisms of procedural stroke make a clinically relevant distinction between intra-procedural and postprocedural strokes. Intra-procedural stroke is defined as hypoperfusion due to clamping (CEA) or dilatation (CAS) and embolization from the carotid plaque (both CEA and CAS). Postprocedural stroke can be caused by thrombo-embolisation but seems to have a primarily hemodynamic origin. Besides thrombotic occlusion of the carotid artery, cerebral hyperperfusion syndrome (CHS) due to extensively increased cerebral revascularization is the most reported pathophysiological mechanism of postprocedural stroke. Multiple technical improvements have attempted to lower the risk of periprocedural stroke. The introduction of antiplatelet therapy (APT) has significantly reduced the risk of thromboembolic events in patients with carotid stenosis. Over the years, recommendations regarding APT changed. While for a long time APT was discontinued prior to surgery because of a fear of increased bleeding risk, nowadays continuation of APT during carotid intervention (aspirin monotherapy or even dual APT including clopidogrel) is found to be safe and effective. In CAS patients, dual APT up to three months' postprocedural is considered best. Stent design and cerebral protection devices (CPD) for CAS procedure are continuously under development. Trials have suggested a benefit of closed-cell stent design over open-cell stent design in order to reduce procedural stroke, while the benefit of CPD during stenting is still a matter of debate. Although CPD reduce the risk of procedural stroke, a higher number of new ischemic brain lesions detected on diffusion weighted imaging was found in patients treated with CPD. In patients undergoing CEA under general anesthesia, adequate use of cerebral monitoring (EEG and transcranial Doppler [TCD]) has reduced the number of intraoperative stroke by detecting embolization and thereby guiding the surgeon to adjust his technique or to selectively shunt the carotid artery. In addition, TCD is able to adequately identify and exclude patients at risk for CHS. For CAS, the additional value of periprocedural cerebral monitoring to prevent strokes needs urgent attention. In conclusion, this review provides an overview of the pathophysiological mechanism of stroke following carotid revascularization (both CAS and CEA) and of the technical improvements that have contributed to reducing this stroke risk.

Subtraction of arterial spin-labeling magnetic resonance perfusion images acquired at dual post-labeling delay: Potential for evaluating cerebral hyperperfusion syndrome following carotid endarterectomy

Arterial spin-labeling magnetic resonance perfusion imaging is a promising tool for the diagnosis of cerebral hyperperfusion syndrome after carotid endarterectomy. However, arterial spin-labeling with a single post-labeling delay has been reported to show a higher incidence of increased arterial spin-labeling signals in the bilateral hemisphere, probably due to a shortening of the arterial transit time or an arterial transit artifact caused by intravascular stagnant magnetically-labeled spin. To overcome these shortcomings, we used two post-labeling delay settings (1.0 and 1.5 s) in 8 patients who had undergone carotid endarterectomy. In addition, we created a subtraction image between the mean perfusion maps at post-labeling delays of 1.0 and 1.5 s. This also decreased arterial transit artifacts, as these appeared in nearly the same configuration in both post-labeling delay settings. In all eight cases examined, increased arterial spin-labeling signals were observed bilaterally on both dual post-labeling delay settings. Subtraction images revealed that these increased signals were attributable to arterial transit artifacts in seven cases. However, in one patient who developed clinical symptoms, the subtraction method demonstrated post-carotid endarterectomy hyperperfusion. This preliminary study demonstrates that the subtraction method might decrease arterial transit artifacts and yield a map that can better represent true perfusion, thus enabling the detection of post-carotid endarterectomy hyperperfusion.

Abstract TP156: A Novel and Logical Strategy for Prevention of Hyperperfusion Syndrome; Intentional Residual Stenosis After Carotid Artery Stenting of an Extremely High-Grade Stenosis

Introduction: Hyperperfusion syndrome ( HPS ) probably occurs after carotid artery stenting ( CAS ) of an extremely high-grade carotid artery stenosis (ex-CS). However, it has not been established how to prevent HPS. Hypothesis: Intentional residual stenosis (iRS ) after CAS not followed by balloon dilatation (bD) can prevent HPS in patients with an ex-CS and spontaneously dilates thereafter. Methods: We included in our study patients with an ex-CS who underwent elective CAS not followed by bD for iRS from 2015 to 2018. We defined an ex-CS as a stenosis of more than NASCET 70% which caused delayed filling of contrast material in an internal carotid angiogram and reduced signal intensity (ratio of less than 0.9) of the ipsilateral middle cerebral artery (MCA) compared to the contralateral MCA on magnetic resonance angiograms (MRA), and defined a residual stenosis (rS) as angiographic stenosis of more than NASCET 30% or peak systolic velocity (PSV) of more than 80 cm/s by Doppler ultrasonography. We defined hyperperfusion phenomenon (HPP) as increase of cerebral blood flow in single photon emission computed tomography scans or cerebral metabolic rate of oxygen by measuring blood oxygen content. We evaluated patients’ baseline characteristics, rS just after CAS, incidence of HPS and HPP. Three months after CAS, they underwent conventional angiographic investigation. Results: During the study period, 26 CAS met our inclusive criteria. Their median carotid stenosis was NASCET 81.8%. Signal intensity ratio of MRA was 0.75. Median PSV before and just after CAS was 311.5 and 76.1 cm/s (p&lt;0.0001). Just after CAS, median stent diameter stenosis was 33.3%. Seventeen patients (65.4%) had angiographic rS. Twelve patients (46.2%) had PSV of more than 80 cm/s. Ten patients had both. Comprehensively nineteen (73.1%) patients had significant rS. Among 26 patients with an ex-CS, no one experienced HPS, although comprehensively 15 patients (57.7%) presented asymptomatic HPP. Among 26 patients, 23 patients finished 3-month angiography and their stents significantly spontaneously dilated (p&lt;0.0001). Conclusion: Intentional residual stenosis after CAS of an ex-CS probably prevented hyperperfusion syndrome and spontaneously dilated at 3 months after CAS.

Abstract TP523: A Randomized Controlled Trial Evaluating the Effectiveness of Pretreatment With the Free Radical Scavenger, Edaravone, Before Carotid Artery Stenting

Objective: Cerebral hyperperfusion syndrome (CHS) is likely to occur after carotid revascularization in patients with severe hemodynamic failure. It is important to control cerebral hyperperfusion phenomenon (CHP) to prevent the development of CHS. To determine whether pretreatment with the free radical scavenger, edaravone, could prevent the onset of CHP after carotid artery stenting (CAS). Methods: Patients with severe carotid artery stenosis were randomized to receive either pretreatment with edaravone immediately before CAS or the common CAS procedure. Cerebral blood flow (CBF) was assessed in the affected middle cerebral artery (MCA) region and in the ipsilateral cerebellum using single-photon emission computed tomography (SPECT) of the brain before and immediately after CAS. Cerebrovascular reactivity (CVR) in the MCA region was also evaluated using the stereotactic extraction estimation based on the Japanese extracranial-intracranial bypass trial (SEE-JET) program and classified as reduced when it was &lt;18.4%. The ratio of MCA to cerebellar activity was defined as the CBF in the affected MCA region divided by the CBF in the ipsilateral cerebellar hemisphere. CHP was defined as an increase in the ratio of MCA to cerebellar activity after CAS ≥10%. Results: Of the 52 patients recruited in this study, 26 were assigned to the pretreatment with edaravone group and 26 were assigned to the treatment as the usual group. Eleven patients showed reduced CVR. CHP occurred in 0 of 6 patients in the edaravone group and in 4 of 5 patients in the usual group (0% vs. 80%, p=0.0152). However, there was no significant difference in the overall patient population between the two groups. Conclusion: Pretreatment with edaravone could reduce the incidence of CHP after CAS in patients with reduced CVR.

Abstract WP175: The Significance of Perfusion Computed Tomography in the Prediction of Hyperperfusion After Carotid Endarterectomy

Purpose: Cerebral hyperperfusion syndrome (CHS) is a rare devastating complication associated with hyperperfusion after carotid endarterectomy. Single photon emission computed tomography (SPECT) is usually used with acetazolamide challenge to measure the cerebrovascular reserve (CVR), and a decreased CVR is indicative of a high risk of post CEA hyperperfusion. However, acetazolamide administration can rarely cause serious adverse effects, and thus, alternative methods may be required. Perfusion computed tomography (PCT) is a rapid, more accessible modality, which can be acquired with CT angiography. PCT seems to be useful as a screening tool in identifying groups at high-risk of hyperperfusion, but its usefulness has not sufficiently investigated. Our purpose was to clarify the relationship between hyperperfusion and the preoperative PCT parameters of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). Method: We included patients who underwent carotid endarterectomy in our hospital from 2014 December to 2018 April. PCT was obtained preoperatively and on postoperative day 1. Hyperperfusion is defined as a postoperative CBF of the middle cerebral artery area which has increased twice that of the preoperative value. CHS was defined as any symptom and imaging findings related with hyperperfusion, which include headache, seizure, neurological dysfunction, and any intracranial hemorrhage in the related area. Preoperative CBF, CBV, MTT and other patient characteristics are statistically analyzed between a hyperperfusion group and non-hyperperfusion group. Result: There are 73 patients who underwent CEA during the study period, and hyperperfusion was observed in 5 cases, from which 2 were considered as CHS. In the hyperperfusion group, the preoperative CBF was significantly lower (p=0.0008), and the CBV and MTT significantly higher (p=0.0196, p=0.0002). ROC analysis showed that the PCT parameters with the maximal area under the receiver-operating characteristic curve for hyperperfusion was preoperative MTT with an optimal threshold at 8.0 seconds (sensitivity 100%, specificity 100%). Conclusion: Patient with prolonged preoperative MTT tend to develop hyperperfusion, which is related to CHS.

Effectiveness of staged angioplasty for avoidance of cerebral hyperperfusion syndrome after carotid revascularization.

Cerebral hyperperfusion syndrome (CHS) is a serious complication after carotid artery stenting (CAS). Staged angioplasty (SAP)-i.e., angioplasty followed by delayed CAS-has been reported as a potential CHS-avoiding procedure. The purpose of this study was to clarify the effectiveness of SAP in avoiding CHS after carotid revascularization for patients at high risk for this complication. The authors retrospectively studied cases involving patients at high risk for CHS from 44 Japanese centers who were scheduled for SAP, regular CAS, angioplasty, or staged procedures other than SAP between October 2007 and March 2014. They investigated the rate of CHS in the population scheduled for SAP or regular CAS, and for safety analysis, the composite rate of transient ischemic attack (TIA) and ischemic stroke in the population eventually receiving SAP or regular CAS. Data from a total of 525 patients (532 lesions, mean age 72.5 ± 7.5 years, 74 women ) were analyzed. Scheduled procedures included SAP for 113 lesions and regular CAS for 419 lesions. The rate of CHS was lower in the SAP group than in the regular CAS group (4.4% vs 10.5%, p = 0.047). Multivariate analysis showed that SAP was negatively related to CHS (OR 0.315; 95% CI 0.120-0.828). In the population eventually receiving SAP (102 lesions) or regular CAS (428 lesions), the composite rate of TIA and ischemic stroke was comparable between the SAP group and the regular CAS group (9.8% vs 9.3%). SAP may be an effective and safe carotid revascularization procedure to avoid CHS.