Hyperperfusion Syndrome Research Articles

Rare Complication of Carotid Stenting: New-Onset Refractory Status Epilepticus: A Study of Five Patients.

Introduction:New-onset refractory status epilepticus (NORSE) is uncommon and almost 50% of cases are cryptogenic. We report the rare development of NORSE following carotid artery stenting (CAS), a procedure which is increasingly being used to treat the carotid stenosis.Materials and Methods:Patients who developed NORSE following CAS for the prevention of stroke over a period of 5 years were analyzed retrospectively. The degree of internal carotid artery stenosis (ICA) was estimated as per the NASCET criteria.Results:We analyzed five patients (age: 56–83 years). NORSE was reported within 30 min to 14 days post-CAS. Status epilepticus was focal in two patients, generalized in two, and one had nonconvulsive status epilepticus. All patients were treated with multiple antiepileptic drugs. Four patients recovered and survived and one succumbed. Two patients had comorbid hypertension and two had diabetes and hypertension. Four patients had hemiparesis due to the contralateral middle cerebral artery territory infarction and one patient had syncope. Two patients had postinfarction gliosis.Conclusions:We report a new cause of NORSE, following CAS. Stroke resulting in gliosis and cerebral hyperperfusion syndrome are the proposed mechanisms.

Platelet Count After Living Donor Liver Transplantation as a Surrogate for Portal Vein Pressure Monitoring and Predictor of Graft Hyperperfusion Syndrome: The “5-67-8” Rule

Platelet Count After Living Donor Liver Transplantation as a Surrogate for Portal Vein Pressure Monitoring and Predictor of Graft Hyperperfusion Syndrome: The “5-67-8” Rule

Subarachnoid Hemorrhage Due to Cerebral Hyperperfusion Syndrome after Carotid Endarterectomy Performed in the Acute Phase of a Cerebral Infarction: A Case Report

Subarachnoid Hemorrhage Due to Cerebral Hyperperfusion Syndrome after Carotid Endarterectomy Performed in the Acute Phase of a Cerebral Infarction: A Case Report

How to identify risk for cerebral hyperperfusion syndrome after carotid revascularization procedures

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CEREBRAL HYPERPERFUSION SYNDROME IN PATIENTS WITH STENOTIC AND OCCLUSIVE LESION INTERNAL CAROTID ARTERIES AFTER SURGERY. LITERATURE REVIEW

The literature on the cerebral hyperperfusion syndrome in patients with stenotic and occlusive lesion internal carotid arteries after surgery has been analyzed.Data of pathogenesis, clinical features, diagnostics, prevention and treatment of cerebral hyperperfusion syndrome are presented. Despite a large number of publications, there are no unified recommendations on treatment and prevention of cerebral hyperperfusion, there are no unified diagnostic criteria. Key words: cerebral hyperperfusion syndrome, EC-IC bypass, carotid endarterectomy, carotid artery stenting.

Carotid Endarterectomy for Medical Therapy-Resistant Symptomatic Low-Grade Stenosis

Plaque characteristics play pivotal roles in ischemic events, but stenosis severity does not accurately reflect carotid plaque volume due to expansive remodeling in some patients with low-grade stenosis (LGS). This study aimed to assess the safety, efficacy, and durability of carotid endarterectomy (CEA) for symptomatic LGS. Study participants comprised 61 consecutive patients who underwent CEA for symptomatic carotid stenosis. Patients were divided into an LGS group (<50%, n= 17) and a non-LGS group (≥50%, n= 44). Patient characteristics and short-term (within 30 days of CEA) and long-term outcomes were compared between groups for selective usage of internal shunt and known complications of CEA. Magnetic resonance imaging-detected intraplaque hemorrhage was more significant in LGS than in non-LGS (P= 0.04). For short-term outcomes, no symptomatic infarcts, hyperperfusion syndrome, or acute myocardial infarction was confirmed in either group. Internal shunts were used in 4 LGS (23.5%) and 6 non-LGS (13.6%). Asymptomatic diffusion-weighted imaging-positive lesions were confirmed in 2 LGS patients (11.8%) and 5 non-LGS patients (11.4%), neck hematoma in 1 LGS patient, and transient cranial nerve palsy in 1 LGS patient and 2 non-LGS patients, with no significant differences apparent between groups. For long-term outcomes, 5 non-LGS patients showed restenosis (P= 0.17). Hemorrhagic stroke was not observed in either group. No significant differences were seen for infarct in the ipsilateral carotid territory, any ischemic stroke, AMI, or mortality. CEA represents a safe and feasible therapeutic option for a subset of patients with symptomatic LGS.

Risk of intracranial hemorrhage after carotid artery stenting versus endarterectomy: a population-based study.

OBJECTIVEIntracranial hemorrhage (ICH) associated with cerebral hyperperfusion syndrome is a rare but major complication of carotid artery revascularization. The objective of this study was to compare the rate of ICH after carotid artery stenting (CAS) with that after endarterectomy (CEA).METHODSThe authors performed a retrospective population-based cohort study of patients who underwent carotid artery revascularization in the province of Ontario, Canada, between 2002 and 2015. The primary outcome was the rate of ICH that occurred within 90 days after carotid artery intervention among patients who underwent CAS versus that of those who underwent CEA. The authors used inverse probability of treatment weighting and propensity scores to account for selection bias. In sensitivity analyses, patients who had postprocedure ischemic stroke were excluded, and the following subgroups were examined: patients with symptomatic and asymptomatic carotid artery stenosis, patients treated between 2010 and 2015, and patients aged ≥ 66 years (to account for antiplatelet and anticoagulant use).RESULTSA total of 16,688 patients underwent carotid artery revascularization (14% CAS, 86% CEA). Patients with more comorbid illnesses, symptomatic carotid artery stenosis, or cardiac disease and those who were taking antiplatelet agents or warfarin before surgery were more likely to undergo CAS. Among the overall cohort, 80 (0.48%) patients developed ICH within 90 days (0.85% after CAS, 0.42% after CEA). The 180-day mortality rate after ICH in the overall cohort was 2.7%, whereas the 180-day mortality rate among patients who suffered ICH was 42.5% (40% for CAS-treated patients, 43.3% for CEA-treated patients). In the adjusted analysis, patients who underwent CAS were significantly more likely to have ICH than those who underwent CEA (adjusted OR 1.77; 95% CI 1.32-2.36; p < 0.001). These results were consistent after excluding patients who developed postprocedure ischemic stroke (adjusted OR 1.90; 95% CI 1.41-2.56) and consistent among symptomatic (adjusted OR 1.74; 95% CI 1.16-2.63) and asymptomatic (adjusted OR 1.75; 95% CI 1.16-2.63) patients with carotid artery stenosis, among patients treated between 2010 and 2015 (adjusted OR 2.21; 95% CI 1.45-3.38), and among the subgroup of patients aged ≥ 66 years (adjusted OR 1.53; 95% CI 1.05-2.24) after adjusting for medication use.CONCLUSIONSCAS is associated with a rare but higher risk of ICH relative to CEA. Future research is needed to devise strategies that minimize the risk of this serious complication after carotid artery revascularization.

ASL perfusion features and type of circle of Willis as imaging markers for cerebral hyperperfusion after carotid revascularization: a preliminary study.

Cerebral hyperperfusion (CH) could be a disastrous outcome causing complication after carotid revascularization if not managed properly and timely. The aim of this study was to investigate the association between preoperative arterial spin labelling (ASL) perfusion features and circle of Willis (CoW) pattern with CH. Forty-eight consecutive carotid stenosis patients who underwent carotid endarterectomy (CEA) or carotid artery stenting (CAS) were enrolled. All patients had single post-labelling delay (PLD) ASL, territory-ASL, and 3-dimensional time-of-flight MR angiography (3D TOF MRA) within 2weeks before surgery and within 3days after surgery. Spatial coefficient of variation (CoV) of cerebral blood flow (CBF), whole brain, and territory perfusion volume ratio were calculated from ASL and territory-ASL. Postoperative CoW was classified into two groups based on patency of the first segment of the anterior cerebral arteries (A1) and anterior communicating artery (AcomA). ASL perfusion features, type of CoW, and clinical characteristics were analyzed between CH group and non-CH group to identify CH risk factors. Higher CoV (p = 0.005) of CBF, lower whole brain perfusion volume ratio (p = 0.012), missing any of A1 or AcomA in CoW (p = 0.002 for postoperative MRA and p = 0.004 for preoperative MRA), and large artery stroke history (p = 0.028) were significantly associated with higher risk of CH. Two cases with cerebral hyperperfusion syndrome (CHS) were also discussed, and their perfusion and angiographic features were shown. Single-PLD ASL and MRA might be useful and non-invasive imaging tools to identify patients with higher risk of CH after carotid revascularization. • Cerebral hyperperfusion is a critical complication after carotid endarterectomy or carotid artery stenting. • ASL and MRA can be used to identify patients at higher risk of cerebral hyperperfusion • Pattern of circle of Willis, ASL perfusion features, and whole brain perfusion volume ratio are potential predicting markers for hyperperfusion after carotid revascularization.

Short-term Outcome of Straight vs Tapered Carotid Stenting for Symptomatic Carotid Artery Stenosis: A Prospective Study

Purpose: To investigate the short-term outcomes and complications of straight vs tapered carotid stent placement for patients with symptomatic carotid stenosis. Methods: A prospective study was conducted to examine if tapered carotid stents (TCS) performed better than straight carotid stents (SCS) in terms of complications and outcomes in patients with a unilateral, symptomatic, internal carotid artery stenosis ⩾70%. Between January 2014 and January 2016, 236 patients were screened; 88 were excluded, leaving 148 patients for 1:1 randomization to carotid artery stenting with either SCS or TCS. The data were analyzed for differences between the groups in terms of complications (hemodynamic depression, cerebral hyperperfusion syndrome, puncture site sequelae) and endpoint events (stroke, myocardial infarction, and death) at 30 days and 6 months. Results: Two patients in the TCS group underwent endarterectomy after allocation, leaving 72 patients (mean age 65.1±8.8 years; 59 men) in the TCS group for analysis vs 74 (mean age 65.0±7.9 years; 58 men) in the SCS group. The technical success was 100% in both groups. The incidence of hemodynamic depression (hypotension and bradycardia) after the procedures were higher in the SCS group (p=0.04), and the patients who underwent SCS procedures had longer hospital stays (p=0.01). There was no difference in the incidences of complications, myocardial infarction, mortality, or stroke at 30 days or 6 months between the SCS and TCS groups. The rates of restenosis (4% SCS vs 1% TCS) were similar (p=0.63); all restenoses were moderate (50%–70%). Conclusion: When compared to straight stents, tapered carotid stents significantly decreased hemodynamic complications and hospital stay.

Rate of complications due to carotid angioplasty in a tertiary university hospital

Introduction: Stenoses greater than 50% in the cervical internal carotid artery cause up to 8% of all ischemic strokes. Carotid artery stenting (CAS) is an effective alternative to prevent cerebrovascular events to occur. According to recommendations from the American Heart Association/American Stroke Association, CAS is indicated for symptomatic patients with internal carotid stenosis greater than 70% (measured by non-invasive methods), as long as the risk for periprocedural stroke or death is less than 6%. There is few information about complication rates of CAS in developing countries. Objectives: The primary goal of this study was to evaluate the frequency of any stroke or death until hospital discharge after CAS in symptomatic patients with carotid stenosis in a tertiary university hospital. Other complication rates were also assessed as secondary aims. Methods: A single-center retrospective study based on the analysis of charts from patients submitted to CAS between April 2011 and March 2016. Inclusion criteria were: age ≥ 18 years old, admission and follow-up by neurologists from the Neurology Ward, performance of CAS according to the hospital´s protocol (carotid stenosis ≥70%, patients with transient ischemic attack (TIA), amaurosis fugax or minor stroke in the last 180 days, and life expectancy greater than a year). Patients not followed by neurologists after CAS were excluded. Results: A total of 65 patients were included: 3 (4.6%) suffered stroke or death after CAS. Two of these patients presented ischemic strokes and one, an hemorrhagic stroke that lead to death. Myocardial infarctions were not identified, as well as carotid ruptures or dissections, hyperperfusion syndrome, artery perforations, stent thrombosis or encephalopathy. Minor complication rates were: 12.3% for hypotension, 9.2% for bradycardia, 1.5% for TIA, 3.1% for carotid vasospasm and 6.2% for acute kidney injury. The total rate of minor complications was 23.1%, and none of then led to permanent harm. Conclusions: The rate of stroke or death in a reference tertiary service in a developing country was in line with international recommendations.

Moyamoya angiopathy: early postoperative course within 3 months after STA-MCA-bypass surgery in Europe-a retrospective analysis of 64 procedures.

Despite the consensus on the necessity of revascularizing surgery in Moyamoya angiopathy in Asia, the indication in Caucasian Moyamoya patients is discussed controversially. The safety of revascularizing surgery in Europe should be clarified. This study retrospectively analyzed the rate of complications as well as clinical symptoms within the first 3months after bypass surgery between superficial temporal artery and middle cerebral artery (STA-MCA). 64 direct bypass procedures in 45 patients (95.5% Caucasians) were analyzed. The magnetic resonance imaging at day 6 showed subdural hematoma in 60.3%. The mean diameter of these hematomas on magnetic resonance imaging was 5.1mm (SD 3.4mm) and increased in 25% at follow-up. No difference was found between those patients with early (day 1) or late (day 7) restarts of antiplatelet therapy. Magnetic resonance imaging at day 6 revealed hyperperfusion syndrome after six of 64 procedures (9.3%). Three of these six had clinical symptoms; two-thirds were transient within seconds. Magnetic resonance imaging depicted stroke after seven procedures (10.9%). Five of these seven patients had no new symptoms. Altogether, after ten procedures (15%), patients complained about clinical symptoms. These were all transient. No new transient ischemic attacks occurred during the 3month follow-up and no new lesions were detected in magnetic resonance imaging. Only two patients underwent surgery for asymptomatic subdural hematoma. All other subdural hematomas resolved spontaneously. Revasculating surgery is a safe procedure in Caucasian patients with Moyamoya angiopathy. The observed complications have a good prognosis.

Intracranial Hemorrhage After Superficial Temporal Artery–Middle Cerebral Artery Direct Anastomosis for Adults with Moyamoya Disease

Intracranial hemorrhage, such as intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and intraventricular hemorrhage (IVH), is an extremely rare complication after surgical revascularization for moyamoya disease (MMD). However, the incidence, timing, prognosis, possible mechanism, and prevention are not well known. Adult patients with MMD who underwent direct bypass or combined bypass and experienced ICH, SAH, or IVH within 7 days postoperatively were enrolled in this study. The medical records and radiologic findings of these patients, together with their intraoperative video recordings, were reviewed retrospectively. Direct superficial temporal artery (STA)-middle cerebral artery (MCA) bypass or combined bypass was performed for 222 hemispheres in 193 adult patients with MMD between January 2001 and December 2016. Intracranial hemorrhage occurred perioperatively in 8 hemispheres (3.6%) in 8 patients. The hemorrhages developed immediately after STA-MCA direct anastomosis during surgery in 3 patients. Hemorrhage on computed tomography and neurologic deterioration were also observed immediately postoperatively in 2 patients and during the postoperative period in 3 patients. Although 4 patients received medical management, neurosurgical treatment was needed in the other 4 patients. One patient died, and 6 patients were left with moderate or severe disabilities. Intracranial hemorrhage (ICH, IVH, or SAH) after direct bypass for adult patients with MMD is an extremely rare but fatal complication. Although these hemorrhages can be associated with hyperperfusion syndrome, no effective prevention has been established.

Biphasic Development of Focal Cerebral Hyperperfusion After Revascularization Surgery for Adult Moyamoya Disease Associated With Autosomal Dominant Polycystic Kidney Disease

BackgroundCerebral hyperperfusion (CHP) syndrome is a potential complication of superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis for moyamoya disease (MMD), but its biphasic and delayed development is extremely rare. Case reportA 47-year-old woman with autosomal dominant kidney disease (ADPKD) presented with transient ischemic attacks due to MMD, and underwent left STA-MCA anastomosis. N-isopropyl-p-[123I] iodoamphetamine single-photon emission computed tomography (123IMP-SPECT) 1 day after surgery revealed asymptomatic CHP at the site of anastomosis. Strict blood pressure control and minocycline hydrochloride relieved CHP at postoperative day 7. However, 2 days later, the patient complained of sensory aphasia, and 123IMP-SPECT demonstrated significant focal CHP at the site of anastomosis accompanying high-intensity signal on magnetic resonance (MR) imaging of fluid attenuated inversion recovery (FLAIR) in her left temporal lobe near the site of anastomosis. We continued strict blood pressure control and additionally administered free radical scavenger (Edaravone) and antiepileptic agents, which gradually improved sensory aphasia. MR imaging and 123IMP-SPECT also confirmed the amelioration of the FLAIR-high lesion and focal CHP in her left temporal lobe. Two months later, the patient underwent right STA-MCA anastomosis without complications. ConclusionsAlthough the underlying mechanism is unknown, biphasic development of focal CHP after revascularization surgery in an MMD patient with ADPKD is unique. Due to the potential vulnerability of the systemic vessels in ADPKD, it is conceivable that intrinsic vascular wall fragility in MMD could be enhanced by ADPKD and have partly led to this rare complication.

Predicting the Occurrence of Hemorrhagic Cerebral Hyperperfusion Syndrome Using Regional Cerebral Blood Flow After Direct Bypass Surgery in Patients with Moyamoya Disease

Superficial temporal artery-middle cerebral artery anastomosis is an established treatment for moyamoya disease. However, hemorrhagic cerebral hyperperfusion syndrome (CHS) leads to poor outcomes. This study aimed to identify predictors of hemorrhagic CHS based on regional cerebral blood flow (rCBF) in patients with moyamoya disease. The study included 251 hemispheres in 155 patients with moyamoya disease who underwent preoperative and postoperative rCBF measurements and superficial temporal artery-middle cerebral artery double anastomosis. We used rCBF increase rate for predicting hemorrhagic CHS. rCBF increase rate was calculated by 2 methods. In method 1, the rCBF value on the operated side was compared with the rCBF value on the nonoperated side. In method 2, the postoperative rCBF value on the operated side was compared with the preoperative rCBF value on the operated side. Patients were classified into 4 groups according to rCBF increase rate to predict risk of hemorrhagic CHS. Hemorrhagic CHS occurred in 7 (2.8%) hemispheres (no children). Severe hemorrhagic CHS occurred in only 1 (0.4%) hemisphere. Hemorrhagic CHS was observed in patients with ≥30% rCBF increase according to method 1 and ≥50% rCBF increase according to method 2 and was most frequently noted in ≥100% rCBF increase. Predictors for hemorrhagic CHS were ≥30% rCBF increase when using method 1 and ≥50% increase when using method2.

Prior Intravenous Stroke Thrombolysis Does Not Increase Complications of Carotid Endarterectomy.

Background and Purpose- Carotid endarterectomy (CEA) is recommended within 14 days after carotid artery stroke to prevent recurrence. However, the optimal timing of CEA after intravenous thrombolysis (IVT) remains unclear. We studied the safety of CEA after IVT while taking into account both stroke recurrence and CEA-related complications. Methods- Patients who underwent IVT followed by CEA in Helsinki University Hospital 2005 to 2016 were withdrawn from prospectively collected registers. The incidence of stroke recurrence during the time between IVT and CEA, peri/postoperative stroke, hyperperfusion syndrome or drug-resistant high blood pressure, and 3-month outcome measured by modified Rankin Scale was recorded. Stroke patients treated with CEA without preceding IVT were used as controls. Results- Altogether 128 CEAs with preceding IVT and 777 CEAs for stroke without IVT were identified. The median time from IVT to CEA was 9 days (range, 0-349 days; interquartile range, 16). Seven patients (5.5%) underwent CEA within 24 hours, 20 (15.6%) within 48 hours and 87 (68.0%) within 2 weeks from IVT. Stroke recurrence in IVT-CEA patients was 5.5% at median 4 days after IVT (range, 0-8 days). Outcome from CEAs performed within 48 hours from IVT did not differ from CEAs performed later with respect to peri/postoperative ischemic strokes (5.0% and 3.7%), hemorrhagic strokes (5.0% and 1.9%), neck hematomas (5.0% and 8.3%), myocardial infarctions (0.0% and 0.9%), or 3-month modified Rankin Scale. There was a tendency toward higher incidence of hyperperfusion syndrome in the patients operated within 48 hours from IVT (20.0% versus 6.5%; P=0.070). The CEA-related stroke rate was similar to that of the operation without thrombolysis. Only smoking was significantly associated with peri/postoperative stroke (odds ratio, 21.82; 95% confidence interval, 1.08-439.58). Conclusions- Time between IVT and CEA was not associated with CEA-related complications. The high rate of stroke recurrence during the waiting time for CEA underscores the importance of shortening surgery delays.

Carotid endarterectomy for severe symptomatic carotid artery stenosis

Objective To investigate the clinical efficacy of carotid endarterectomy (CEA) in the treatment of extremely severe symptomatic carotid artery stenosis (stenosis rate 95%-99%). Methods The clinical data of 30 patients with extremely severe symptomatic carotid artery stenosis were analyzed retrospectively. Those patients were admitted to Department of Neurosurgery, the First Affiliated Hospital of Soochow University between January 2013 and December 2016. Among them, 14 cases underwent conventional CEA, 11 cases received patch CEA and 5 cases underwent eversion CEA. Cerebral hemisphere perfusion was evaluated with CT Perfusion (CTP) and cerebrovascular collateral circulation was evaluated with DSA or CTA. Results All 30 cases of CEA were performed successfully. CTP was reviewed at 1 week post surgery and all patients had a higher CBF (cerebral blood flow) compared with presurgical states (65.1±8.9 ml·100 g-1·min-1vs. 48.5±5.1 ml·100 g-1·min-1,P<0.05), and the TTP (time-to-peak) was significantly shorter than that prior to surgery (9.8±2.8 s vs. 13.4±1.6 s, P<0.05). After operation, 3 cases suffered from hyperperfusion syndrome. There was no perioperative stroke or death. The duration of follow-up was 3-48 months (mean: 20±12 months). No patient developed a new stroke.No reocclusion was detected. Conclusion CEA seems to be a safe and effective treatment for extremely severe symptomatic carotid artery stenosis. Key words: Carotid stenosis; Atherosclerosis; Endarterectomy, carotid; Treatment outcome

Staged carotid artery stenting in patients with severe carotid stenosis: Multicenter experience

Cerebral hyperperfusion syndrome (CHS) is serious complication after carotid artery stenting (CAS) caused by decreased cerebral vasoreactivity (CVR) due to long standing hypoperfusion of the brain. We hypothesized that partial dilatation of carotid stenosis would allow the recovery of CVR, and prevent CHS when definitive angioplasty with stent is performed afterward. In this study, we aimed to evaluate the safety and efficacy of staged CAS in patients with severe carotid artery stenosis with evident hemodynamic compromise in regard to preventing hyperperfusion syndrome. From January 2005 to February 2016, 53 patients with 55 severe carotid artery stenosis lesions showing decreased CVR and/or cerebral basal flow at the perfusion studies underwent staged CAS in three institutes. The procedure consisted of initial partial balloon angioplasty (BA), recovery period, and delayed definitive stenting (DS). We analyzed immediate results, complications, recoil and CHS related to staged CAS. We experienced no symptomatic manifestation of CHS except self-limited headache after the procedures. The median of intervals between BA and DS stages were 10 days. There was no case of severe recoil during the interval between BA and DS stage. Where perfusion imaging data was available, hyperperfusion was present in three and one patients after BA and DS stage, respectively, with no clinical symptom of CHS. In conclusion, staged CAS was feasible in patients with severe carotid artery stenosis and hemodynamic compromise, without inducing severe complication of CHS such as intracranial hemorrhage.

Assessment of Hemodynamic Changes and Hyperperfusion Risk After Extracranial-to-Intracranial Bypass Surgery Using Intraoperative Indocyanine Green–Based Flow Analysis

Intraoperative blood flow assessments during cerebral bypass would ideally assess vessel patency, downstream perfusion, and risk of postoperative hyperperfusion syndrome (HPS). Previous studies using indocyanine green-based flow analyses (ICG-BFA) have identified multiple parameters that can intraoperatively track bypass-related changes in cerebral perfusion and potentially predict postoperative risk of HPS. Herein, we determine the most robust parameter and anatomic location for intraoperative ICG-BFA assessment of bypass-related perfusion changes and prediction of postoperative risk of HPS. Retrospective analysis of an institutional review board-approved prospective database identified patients undergoing superficial temporal artery-to-middle cerebral artery bypass. Demographic and clinical information, as well as manually calculated and automated pre- and postbypass intraoperative ICG-BFA data from cortical, arterial, and venous regions of interest were recorded and analyzed. Seven patients underwent superficial temporal artery-to-middle cerebral artery bypass (4 Moyamoya, 3carotid occlusions). Average age was 48.2 ± 13.9 years (3female, 4 male). Although all parameters measured showed trends toward improvement postbypass, only changes in arterial and venous automated ICG-BFA slope (also known as blood flow index [maximum intensity/rise time]) reached significance. None of the patients experienced symptomatic HPS, despite 5 of 7 (71.4%) having an increased HPS risk based on previously published ICG-BFA data. ICG-BFA has utility for the intraoperative assessment of bypass-related changes in cerebral perfusion, with automated blood flow index being the most robustly affected parameter. Although previously published ICG-BFA indices did not predict the development of symptomatic postoperative HPS, larger-scale studies correlating observed ICG-BFA changes with risk of HPS are warranted.

Cerebral Hyperperfusion Syndrome After Carotid Revascularization and Acute Ischemic Stroke.

Cerebral hyperperfusion syndrome (CHS) is a rare but significant complication after carotid revascularization and is increasingly recognized after acute stroke treatments. In this review, we discuss the epidemiology and pathophysiology of CHS, clinical presentation including ipsilateral headache, seizures, and focal neurological deficits, and radiographic presentation. We propose preventive therapies with emphasis on acute stroke post-thrombectomy hyperperfusion. CHS was first described after carotid revascularization but is now also reported in patients with acute ischemic stroke. Proposed criteria involve a combination of new clinical symptoms, radiographic evidence of hyperperfusion, and/or presence of intracerebral hemorrhage occurring within 30days after the carotid or intracranial vessel manipulation. Strongest risk factors include reduced cerebral vasoreactivity, contralateral stenosis of ≥ 70%, post-procedure hypertension, and recent ipsilateral stroke. Pathophysiology is incompletely understood but is likely due to increase in cerebral blood flow and impaired cerebral autoregulation, particularly in the areas of disrupted blood-brain barrier, as well as baroreceptor dysfunction during carotid surgery. Strict blood pressure control pre-, during, and post-procedure is recommended, depending on the recanalization status of the vessel. However, there is no randomized data regarding the goal blood pressure to prevent cerebral hyperperfusion syndrome. With technical advances, carotid or intracranial vessel manipulation is increasingly common. CHS is a likely under-recognized and serious complication of carotid revascularization and intracranial thrombectomy. Awareness of and surveillance for CHS is important to reduce morbidity and mortality. Future research should focus on validation of proposed diagnostic criteria and determining optimal post-procedure hemodynamic management to prevent CHS.

Cerebral Hyperperfusion Syndrome After Revascularization Surgery in Moyamoya Disease: Region-Symptom Mapping and Estimating a Critical Threshold.

Cerebral hyperperfusion complicates the postoperative course of patients with moyamoya disease after direct revascularization surgery. There is no clear distinction between cerebral hyperperfusion syndrome and benign postoperative increase in regional cerebral blood flow (rCBF). The present study aimed to determine clinically relevant changes in rCBF, anatomical correlations, and factors associated with transient neurologic symptoms after revascularization surgery in moyamoya disease. Whole-brain voxel-based perfusion mapping was used to identify regions involved in cerebral hyperperfusion and quantify the changes in 105 hemispheric surgeries with the use of single-photon computed tomography acquired on postoperative day 7. The changes in rCBF were quantitatively analyzed, and associations with cerebral hyperperfusion syndrome were determined. Transient neurologic symptoms appeared with rCBF increase in 37.9% of adults. Speech impairments were associated with an increase in rCBF in the operculo-insula region. Cheiro-oral syndrome was associated with the posterior insula as well as the prefrontal region. A receiver operating curve analysis yielded transient neurologic symptoms with maximum accuracy at >15.5% increase from baseline. Age and preoperative rCBF were independently associated with transient neurologic symptoms (P < 0.001). Areas showing rCBF increase during the experience of transient neurologic symptoms were spatially compatible with the known functional anatomy of the brain. An increase of approximately 15% from baseline was found to be critical, which is a far lower threshold than what has been reported previously. Increasing age was significantly associated with the occurrence of symptomatic hyperperfusion. Furthermore, patients with preserved rCBF also showed symptomatic hyperperfusion.