Hyperperfusion after Endovascular Reperfusion Therapy for Acute Ischemic Stroke

Ischemia-reperfusion injury in a salvaged penumbra: Longitudinal high-tesla perfusion magnetic resonance imaging in a rat model

INTRODUCTION

Although ischemia-reperfusion (I/R) injury varies between cortical and subcortical regions, its effects on specific regions remain unclear. In this study, we used various magnetic resonance imaging (MRI) techniques to examine the spatiotemporal dynamics of I/R injury within the salvaged ischemic penumbra (IP) and reperfused ischemic core (IC) of a rodent model, with the aim of enhancing therapeutic strategies by elucidating these dynamics.

MATERIALS AND METHODS

A total of 17 Sprague-Dawley rats were subjected to 1 h of transient middle cerebral artery occlusion with a suture model. MRI, including diffusion tensor imaging (DTI), T2-weighted imaging, perfusion-weighted imaging, and T1 mapping, was conducted at multiple time points for up to 5 days during the I/R phases. The spatiotemporal dynamics of blood-brain barrier (BBB) modifications were characterized through changes in T1 within the IP and IC regions and compared with mean diffusivity (MD), T2, and cerebral blood flow.

RESULTS

During the I/R phases, the MD of the IC initially decreased, normalized after recanalization, decreased again at 24 h, and peaked on day 5. By contrast, the IP remained relatively stable. Both the IP and IC exhibited hyperperfusion, with the IP reaching its peak at 24 h, followed by resolution, whereas hyperperfusion was maintained in the IC until day 5. Despite hyperperfusion, the IP maintained an intact BBB, whereas the IC experienced persistent BBB leakage. At 24 h, the IC exhibited an increase in the T2 signal, corresponding to regions exhibiting BBB disruption at 5 days.

CONCLUSIONS

Hyperperfusion and BBB impairment have distinct patterns in the IP and IC. Quantitative T1 mapping may serve as a supplementary tool for the early detection of malignant hyperemia accompanied by BBB leakage, aiding in precise interventions after recanalization. These findings underscore the value of MRI markers in monitoring ischemia-specific regions and customizing therapeutic strategies to improve patient outcomes.

Global hyperperfusion after successful endovascular thrombectomy is linked to worse outcome in acute ischemic stroke

Patients with stroke may develop hyperperfusion after a successful endovascular thrombectomy (EVT). However, the relationship between post-EVT hyperperfusion and clinical outcomes remains unclear and requires further clarification. We reviewed consecutive patients with anterior circulation occlusion who were successfully recanalized with EVT. Based on post-EVT arterial spin-labeling images, hyperperfusion was categorized as follows: global hyperperfusion (GHP), increased cerebral blood flow (CBF) in ≥ 50% of the culprit vessel territory; focal hyperperfusion (FHP), increased CBF in < 50% of the culprit vessel territory; no hyperperfusion (NHP), no discernible CBF increase. Factors associated with hyperperfusion were assessed, and clinical outcomes were compared among patients under different hyperperfusion categories. Among 131 patients, 25 and 40 patients developed GHP and FHP, respectively. Compared to other groups, the GHP group had worse National Institutes of Health Stroke Scale score (GHP vs. NHP/FHP, 18.1 ± 7.4 vs. 12.3 ± 6.0; p < 0.001), a larger post-EVT infarct volume (98.9 [42.3-132.7] vs. 13.5 [5.0-34.1] mL; p < 0.001), and a worse 90-day outcome (modified Rankin Scale, 3 [1-4] vs. 2 [0-3]; p = 0.030). GHP was independently associated with infarct volume (B = 0.532, standard error = 0.163, p = 0.001), and infarct volume was a major mediator of the association of GHP with unfavorable outcomes (total effect: β = 0.176, p = 0.034; direct effect: β = 0.045, p = 0.64; indirect effect: β = 0.132, p = 0.017). Patients presenting with post-EVT GHP had poorer neurological prognosis, which is likely mediated by a large infarct volume.

Cerebral hyperperfusion syndrome after endovascular reperfusion therapy for medium vessel occlusion: A case report

Cerebral hyperperfusion syndrome is a rare but serious complication after revascularization procedures for cerebrovascular diseases. Cerebral hyperperfusion syndrome can develop after treatment of acute ischemic stroke, including intravenous thrombolysis and endovascular treatment of large vessel occlusion. However, to the best of our knowledge, there are no previous reports describing cerebral hyperperfusion syndrome after endovascular treatment of medium vessel occlusion (eg, anterior cerebral artery A2/3 segment). We report a case of cerebral hyperperfusion syndrome after endovascular reperfusion therapy for medium vessel occlusion. A 70-year-old woman with a history of hypertension and dyslipidemia was transferred by ambulance to our hospital because of immobility and slurred speech. She had mild right lower extremity paralysis, and her symptoms appeared improved compared with onset. She was diagnosed with cerebral infarction in the left frontal lobe. After hospitalization, her neurological symptoms worsened and she was referred to our department. We performed endovascular reperfusion therapy for left anterior cerebral artery A2 occlusion. Recanalization was achieved with residual stenosis. Despite the lack of complications associated with the procedure, the patient had prolonged disorientation, severe hemiplegia, and aphasia. Arterial spin labeling demonstrated hyperperfusion in the left anterior cerebral artery area. The symptoms gradually improved under strict blood pressure control. This report provides evidence that cerebral hyperperfusion syndrome can occur even after endovascular treatment for medium vessel occlusion. Arterial spin labeling was useful in detecting hyperperfusion.

Hemodynamic predictors of early neurological deterioration and clinical outcome after endovascular treatment in large artery occlusion

Objective

Half of the patients with acute large artery occlusion (LAO) have poor outcomes after endovascular treatment (EVT). Early complications such as cerebral edema and symptomatic intracranial hemorrhage (sICH) can lead to early neurological deterioration (END), which correlates with hemodynamics. This study aimed to identify the hemodynamic predictors of END and outcomes in LAO patients after EVT.

Methods

A total of 76 patients with anterior circulation LAO who underwent EVT and received transcranial Doppler (TCD) monitoring were included. Bilateral middle cerebral artery (MCA) blood flow velocities (BFVs) were measured repeatedly within 1 week. Mean flow velocities (MFV) and MFV index (ipsilateral MFV/contralateral MFV) were calculated. The primary outcome was the incidence of END within 72 h. The secondary outcome was the functional outcome at 90 days-a good outcome was defined as a modified Rankin scale (mRS) score of 0-2, while a poor outcome was defined as an mRS score of 3-6.

Results

A total of 13 patients (17.1 %) experienced END within 72 h, including 5 (38.5 %) with cerebral edema, 5 (38.5 %) with sICH, and 3 (23.0 %) with infarct progression. Multivariable logistic regression analysis showed that a higher 24 h MFV index was independently associated with END (aOR 10.5; 95 % CI 2.28-48.30, p = 0.003) and a poor 90-day outcome (aOR 5.10; 95 % CI 1.38-18.78, p = 0.014). The area under the receiver operating characteristic (ROC) curve (AUC) of the 24 h MFV index for predicting END was 0.807 (95 % CI 0.700-0.915, p = 0.0005), the sensitivity was 84.6 %, and the specificity was 66.7 %. At the 1-week TCD follow-up, patients who had poor 90-day outcomes showed significantly higher 1-week iMFV [73.5 (58.4-99.0) vs. 57.7 (45.3-76.3), p = 0.004] and MFV index [1.24 (0.98-1.57) vs.1.0 (0.87-1.15) p = 0.007]. A persistent high MFV index (PHMI) was independently associated with a poor outcome (aOR 7.77, 95 % CI 1.81-33.3, p = 0.006).

Conclusion

TCD monitoring within 24 h after EVT in LAO patients can help predict END, while dynamic follow-up within 1 week is valuable in predicting clinical outcomes.

Implications of Post-recanalization Perfusion Deficit After Acute Ischemic Stroke: a Scoping Review of Clinical and Preclinical Imaging Studies

The goal of reperfusion therapy for acute ischemic stroke (AIS) is to restore cerebral blood flow through recanalization of the occluded vessel. Unfortunately, successful recanalization does not always result in favorable clinical outcome. Post-recanalization perfusion deficits (PRPDs), constituted by cerebral hypo- or hyperperfusion, may contribute to lagging patient recovery rates, but its clinical significance remains unclear. This scoping review provides an overview of clinical and preclinical findings on post-ischemic reperfusion, aiming to elucidate the pattern and consequences of PRPD from a translational perspective. The MEDLINE database was searched for quantitative clinical and preclinical studies of AIS reporting PRPD based on cerebral circulation parameters acquired by translational tomographic imaging methods. PRPD and stroke outcome were mapped on a charting table, creating an overview of PRPD after AIS. Twenty-two clinical and twenty-two preclinical studies were included. Post-recanalization hypoperfusion is rarely reported in clinical studies (4/22) but unequivocally associated with detrimental outcome. Post-recanalization hyperperfusion is more commonly reported (18/22 clinical studies) and may be associated with positive or negative outcome. PRPD has been replicated in animal studies, offering mechanistic insights into causes and consequences of PRPD and allowing delineation of possible courses of PRPD. Complex relationships exist between PRPD and stroke outcome. Diversity in methods and lack of standardized definitions in reperfusion studies complicate the characterization of reperfusion patterns. Recommendations are made to advance the understanding of PRPD mechanisms and to further disentangle the relation between PRPD and disease outcome.

Post-ischemic hyperemia following endovascular therapy for acute stroke is associated with lesion growth

A substantial proportion of acute stroke patients fail to recover following successful endovascular therapy (EVT) and injury to the brain and vasculature secondary to reperfusion may be a contributor. Acute stroke patients were included with: i) large vessel occlusion of the anterior circulation, ii) successful recanalization, and iii) evaluable MRI early after EVT. Presence of hyperemia on MRI perfusion was assessed by consensus using a modified ASPECTS. Three different approaches were used to quantify relative cerebral blood flow (rCBF). Sixty-seven patients with median age of 66 [59-76], 57% female, met inclusion criteria. Hyperemia was present in 35/67 (52%) patients early post-EVT, in 32/65 (49%) patients at 24 hours, and in 19/48 (40%) patients at 5 days. There were no differences in incomplete reperfusion, HT, PH-2, HARM, severe HARM or symptomatic ICH rates between those with and without early post-EVT hyperemia. A strong association (R2 = 0.81, p < 0.001) was found between early post-EVT hyperemia (p = 0.027) and DWI volume at 24 hours after adjusting for DWI volume at 2 hours (p < 0.001) and incomplete reperfusion at 24 hours (p = 0.001). Early hyperemia is a potential marker for cerebrovascular injury and may help select patients for adjunctive therapy to prevent edema, reperfusion injury, and lesion growth.

Non responsible vascular area hyperperfusion syndrome after mechanical thrombectomy for vertebral artery occlusion: A case report

Introduction

There are currently no published reports of hyperperfusion syndrome in the non responsible vascular area after mechanical thrombectomy for acute cerebral infarction with large vessel occlusion. Here, we report a case of hyperperfusion syndrome in the blood supply area of the right middle cerebral artery after mechanical thrombectomy for acute cerebral infarction after vertebral artery occlusion.

Patient concerns

A 21-year-old woman developed left vertebral artery occlusion, for which she received mechanical thrombectomy and successful recanalization of her occluded cerebral vessel. Subsequently, the patient became extremely agitated, with high blood pressure and headache.

Diagnosis

Two hours after the operation, bedside transcranial Doppler ultrasound examination found that the cerebral blood flow velocity of the M1 segment of the right middle cerebral artery was more than twice that of the left middle cerebral artery. Combined with the symptoms, signs and examination results of the patient, hyperperfusion syndrome in the blood supply area of the right middle cerebral artery was considered.

Interventions

The patient was administered sedation, and her pressure and ventricular rate were strictly controlled. She was no longer agitated, and her headache was significantly relieved at 36 hours after the operation.

Outcomes

On the 5th day after the operation, the blood flow velocity of her right middle cerebral artery decreased to normal level, and the patient recovered well.

Conclusion

In this case, after mechanical thrombectomy, such patients with acute posterior circulation cerebral infarction can experience hyperperfusion syndrome in the non responsible vascular area of the anterior circulation. Bedside transcranial Doppler cerebral blood flow examination can identify the hyperperfusion state of cerebral vessels in a timely manner and effectively guide treatment.

Cerebral hyperperfusion syndrome after stenting for revascularization of intracranial internal carotid artery dissection

Cerebral hyperperfusion syndrome (CHS) is one of the complications of cerebral revascularization. The main pathophysiology of CHS was considered to be cerebral autoregulation impairment due to long-standing cerebral hypoperfusion. Herein, we describe the case of a 40-year-old man with symptomatic intracranial arterial dissection (IAD) related to internal carotid artery stenosis. The patient underwent intracranial stenting 11 days after onset due to severe cerebral hypoperfusion presenting with neurological symptoms, and CHS presenting with intracerebral hemorrhage, post-operatively. The present case indicated not only the potential risk of CHS after intracranial stenting in IAD-related stenosis but also that cerebral hypoperfusion-even in a short period-might lead to CHS.

MRI arterial spin labeling in evaluating hemorrhagic transformation following endovascular recanalization of subacute ischemic stroke

Objective

To investigate the value of the MRI arterial spin labeling (ASL) in evaluating the blood-brain barrier permeability of anterior circulation ischemic lesions in subacute ischemic stroke (SIS) and the risk of hemorrhage transformation (HT) after endovascular recanalization.

Materials and methods

Patients with anterior circulation SIS treated with endovascular recanalization were prospectively enrolled. The imaging presentations in the MRI ASL sequences, dynamic contrast-enhanced (DCE) sequence, and Xper CT were studied. The relative cerebral blood flow (rCBF), volume transfer constant (Ktrans), and the weighted Kappa coefficient (rKtrans) were analyzed.

Results

Among 27 eligible patients, HT occurred in 7 patients (25.92%). Patients with HT had significantly higher rCBF value (1.56 ± 0.16 vs. 1.16 ± 0.16), Ktrans, (0.08 ± 0.03 min vs. 0.03 ± 0.01 min) and rKtrans (3.02 ± 0.89 vs. 1.89 ± 0.56). The ASL imaging sequence had a high consistency with the DCE sequence and Xper CT with a high weighted Kappa coefficient of 0.91 for the DCE sequence and 0.70 for the Xper CT imaging. The DCE sequence was also highly consistent with the Xper CT in imaging classification with a high weighted Kappa coefficient of 0.78. The rCBF value in the 21 patients with the subcortical and basal ganglia infarction was significantly lower than that in the other 6 patients with the cortical infarction (1.222 ± 0.221 vs. 1.413 ± 0.259, t = 1.795, P = 0.004).

Conclusion

The MRI ASL sequence has an important role in evaluating the blood-brain barrier permeability and the risk of hemorrhagic transformation of anterior circulation SIS following endovascular recanalization.

Association between Infarct Location and Hemorrhagic Transformation of Acute Ischemic Stroke following Successful Recanalization after Mechanical Thrombectomy

BACKGROUND AND PURPOSE

The association between infarct location and hemorrhagic transformation of acute ischemic stroke after mechanical thrombectomy is not understood. We aimed to evaluate the association between CTP-based ischemic core variables at admission and hemorrhagic transformation after a successful thrombectomy.

MATERIALS AND METHODS

We retrospectively analyzed patients who underwent endovascular thrombectomy for acute anterior circulation large-vessel occlusion between October 2019 and June 2021. We enrolled 146 patients with visible ischemic core on pretreatment CTP who had successful reperfusion. The ischemic core infarct territories were classified into the cortical and subcortical areas and then qualitatively and quantitatively analyzed by CTP. Logistic regression and receiver operating characteristic curve analyses were performed to determine the association between ischemic core variables and hemorrhagic transformation.

RESULTS

Of the 146 patients analyzed, 72 (49.3%) had hemorrhagic transformation and 23 (15.8%) had symptomatic intracerebral hemorrhage. Multivariate analysis showed that subcortical infarcts were independently associated with hemorrhagic transformation (OR, 8.06; 95% CI, 2.31-28.10; P = .001) and subcortical infarct volume was independently linked to symptomatic intracerebral hemorrhage (OR, 1.05; 95% CI, 1.01-1.09; P = .039). The receiver operating characteristic curve indicated that subcortical infarcts can predict hemorrhagic transformation accurately (area under the curve = 0.755; 95% CI, 0.68-0.82; P < .001) and subcortical infarct volume can predict symptomatic intracerebral hemorrhage (area under the curve = 0.694; 95% CI, 0.61-0.77; P = .002).

CONCLUSIONS

Subcortical infarcts seen on CTP at admission are associated with hemorrhagic transformation in patients after successful thrombectomy, and subcortical infarct volume may influence the risk of symptomatic intracerebral hemorrhage.

Cerebral blood flow quantification with multi-delay arterial spin labeling in ischemic stroke and the association with early neurological outcome

Restoring blood flow to brain tissue at risk of infarction is essential for tissue survival and clinical outcome. We used cerebral blood flow (CBF) quantified with multiple post-labeling delay (PLD) pseudocontinuous arterial spin labeling (ASL) MRI after ischemic stroke and assessed the association between CBF and early neurological outcome. We acquired ASL with 7 PLDs at 3.0 T in large vessel occlusion stroke patients at 24 h. We quantified CBF relative to the contralateral hemisphere (rCBF) and defined hyperperfusion as a ≥30% increase and hypoperfusion as a ≥40% decrease in rCBF. We included 44 patients (median age: 70 years, median NIHSS: 13, 40 treated with endovascular thrombectomy) of whom 37 were recanalized. Hyperperfusion in ischemic core occurred in recanalized but not in non-recanalized patients (65.8% vs 0%, p = 0.006). Hypoperfusion occurred only in the latter group (0% vs 85.7%, p < 0.001). In recanalized patients, hyperperfusion was also seen in salvaged penumbra (38.9%). Higher rCBF in ischemic core (aβ, -2.75 [95% CI: -4.11 to -1.40]) and salvaged penumbra (aβ, -5.62 [95% CI: -9.57 to -1.68]) was associated with lower NIHSS scores at 24 h. In conclusion, hyperperfusion frequently occurs in infarcted and salvaged brain tissue following successful recanalization and early neurological outcome is positively associated with the level of reperfusion.

Prevalence and Significance of Impaired Microvascular Tissue Reperfusion Despite Macrovascular Angiographic Reperfusion (No-Reflow)

BACKGROUND AND OBJECTIVES

The relevance of impaired microvascular tissue-level reperfusion despite complete upstream macrovascular angiographic reperfusion (no-reflow) in human stroke remains controversial. We investigated the prevalence and clinical-radiologic features of this phenomenon and its associations with outcomes in 3 international randomized controlled thrombectomy trials with prespecified follow-up perfusion imaging.

METHODS

In a pooled analysis of the Extending the Time for Thrombolysis in Emergency Neurological Deficits-Intra-Arterial (EXTEND-IA; ClinicalTrials.gov NCT01492725), Tenecteplase Versus Alteplase Before Endovascular Therapy for Ischemic Stroke (EXTEND-IA TNK; NCT02388061), and Determining the Optimal Dose of Tenecteplase Before Endovascular Therapy for Ischaemic Stroke (EXTEND-IA TNK Part 2; NCT03340493) trials, patients undergoing thrombectomy with final angiographic expanded Treatment in Cerebral Infarction score of 2c to 3 score for anterior circulation large vessel occlusion and 24-hour follow-up CT or MRI perfusion imaging were included. No-reflow was defined as regions of visually demonstrable persistent hypoperfusion on relative cerebral blood volume or flow maps within the infarct and verified quantitatively by >15% asymmetry compared to a mirror homolog in the absence of carotid stenosis or reocclusion.

RESULTS

Regions of no-reflow were identified in 33 of 130 patients (25.3%), encompassed a median of 60.2% (interquartile range 47.8%-70.7%) of the infarct volume, and involved both subcortical (n = 26 of 33, 78.8%) and cortical (n = 10 of 33, 30.3%) regions. Patients with no-reflow had a median 25.2% (interquartile range 16.4%-32.2%, p < 0.00001) relative cerebral blood volume interside reduction and 19.1% (interquartile range 3.9%-28.3%, p = 0.00011) relative cerebral blood flow reduction but similar mean transit time (median -3.3%, interquartile range -11.9% to 24.4%, p = 0.24) within the infarcted region. Baseline characteristics were similar between patients with and those without no-reflow. The presence of no-reflow was associated with hemorrhagic transformation (adjusted odds ratio [aOR] 1.79, 95% confidence interval [CI] 2.32-15.57, p = 0.0002), greater infarct growth (β = 11.00, 95% CI 5.22-16.78, p = 0.00027), reduced NIH Stroke Scale score improvement at 24 hours (β = -4.06, 95% CI 6.78-1.34, p = 0.004) and being dependent or dead at 90 days as assessed by the modified Rankin Scale (aOR 3.72, 95% CI 1.35-10.20, p = 0.011) in multivariable analysis.

DISCUSSION

Cerebral no-reflow in humans is common, can be detected by its characteristic perfusion imaging profile using readily available sequences in the clinical setting, and is associated with posttreatment complications and being dependent or dead. Further studies evaluating the role of no-reflow in secondary injury after angiographic reperfusion are warranted.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that cerebral no-reflow on CT/MRI perfusion imaging at 24 hours is associated with posttreatment complications and poor 3-month functional outcome.

Cortical Neural Damage Associated with Cerebral Hyperperfusion after Reperfusion Therapy for Acute Ischemic Stroke: 123I-iomazenil Single-photon Emission Computed Tomography Findings

We present an 88-year-old man with cerebral hyperperfusion (CH) after acute reperfusion therapy. He developed acute cerebral ischemia as a result of occluded middle cerebral artery that was subsequently recanalized with endovascular thrombectomy. I-123 N-isopropyl-p-iodoamphetamine single-photon emission computed tomography (SPECT) after reperfusion therapy showed increased cerebral blood flow (CBF) in brain areas that exhibited no abnormal findings on magnetic resonance imaging (MRI). Follow-up MRI did not demonstrate structural brain damage associated with CH. However, later I-123 iomazenil SPECT imaging showed a reduction in benzodiazepine receptor binding potential (BRBP) in these areas, a finding that correlates with cortical neural damage. CH is being increasingly observed after endovascular treatment for acute stroke. However, little is known about CH when not associated with cerebral hemorrhage or infarction. The role of CH after reperfusion therapy in causing brain damage remains unclear. BRBP on I-123 iomazenil SPECT images is useful to evaluate brain neural density: a reduction in cortical BRBP indicates cortical neural damage or loss. Our findings suggest that post-reperfusion hyperperfusion induces cortical neural damage even in the absence of associated brain infarction or hemorrhage on MRI. Early postoperative SPECT is recommended to detect CH after acute reperfusion therapy. CH should be considered when the recovery from stroke is unexpectedly poor for a patient.

Microvascular Dysfunction in Blood-Brain Barrier Disruption and Hypoperfusion Within the Infarct Posttreatment Are Associated With Cerebral Edema

BACKGROUND AND PURPOSE

Factors contributing to cerebral edema in the post-hyperacute period of ischemic stroke (first 24-72 hours) are poorly understood. Blood-brain barrier (BBB) disruption and postischemic hyperperfusion reflect microvascular dysfunction and are associated with hemorrhagic transformation. We investigated the relationships between BBB integrity, cerebral blood flow, and space-occupying cerebral edema in patients who received acute reperfusion therapy.

METHODS

We performed a pooled analysis of patients treated for anterior circulation large vessel occlusion in the EXTEND-IA TNK and EXTEND-IA TNK part 2 trials who had MRI with dynamic susceptibility contrast-enhanced perfusion-weighted imaging 24 hours after treatment. We investigated the associations between BBB disruption and cerebral blood flow within the infarct with cerebral edema assessed using 2 metrics: first midline shift (MLS) trichotomized as an ordinal scale of negligible (<1 mm), mild (≥1 to <5 mm), or severe (≥5 mm), and second relative hemispheric volume (rHV), defined as the ratio of the 3-dimensional volume of the ischemic hemisphere relative to the contralateral hemisphere.

RESULTS

Of 238 patients analyzed, 133 (55.9%) had negligible, 93 (39.1%) mild, and 12 (5.0%) severe MLS at 24 hours. The associated median rHV was 1.01 (IQR, 1.00-1.028), 1.03 (IQR, 1.01-1.077), and 1.15 (IQR, 1.08-1.22), respectively. MLS and rHV were associated with poor functional outcome at 90 days (P<0.002). Increased BBB permeability was independently associated with more edema after adjusting for age, occlusion location, reperfusion, parenchymal hematoma, and thrombolytic agent used (MLS cOR, 1.12 [95% CI, 1.03-1.20], P=0.005; rHV β, 0.39 [95% CI, 0.24-0.55], P<0.0001), as was reduced cerebral blood flow (MLS cOR, 0.25 [95% CI, 0.10-0.58], P=0.001; rHV β, -2.95 [95% CI, -4.61 to -11.29], P=0.0006). In subgroup analysis of patients with successful reperfusion (extended Treatment in Cerebral Ischemia 2b-3, n=200), reduced cerebral blood flow remained significantly associated with edema (MLS cOR, 0.37 [95% CI, 0.14-0.98], P=0.045; rHV β, -2.59 [95% CI, -4.32 to -0.86], P=0.004).

CONCLUSIONS

BBB disruption and persistent hypoperfusion in the infarct after reperfusion treatment is associated with space-occupying cerebral edema. Further studies evaluating microvascular dysfunction during the post-hyperacute period as biomarkers of poststroke edema and potential therapeutic targets are warranted.

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.

Luxury Perfusion Producing Sensory Aphasia

We describe the case of an 86-year-old Japanese man who, by luxury perfusion after spontaneous recanalization of the left middle cerebral artery/internal carotid artery, produced acute transient sensory aphasia. This rare phenomenon is thought to be caused by reperfusion brain injury.

Early Venous Filling Following Thrombectomy: Association With Hemorrhagic Transformation and Functional Outcome

Background and Purpose: Previous studies have noted the angiographic appearance of early venous filling (EVF) following recanalisation in acute ischemic stroke. However, the prognostic implications of EVF as a novel imaging biomarker remain unclear. We aimed to evaluate the correlation between EVF with (i) the risk of subsequent reperfusion hemorrhage (RPH) and (ii) the association of EVF on both the NIHSS score at 24 h and functional outcome as assessed with the Modified Rankin Scale (mRS) score at 90 days. Methods: We conducted a retrospective cohort study of patients presenting with an acute ischemic stroke due to a proximal large-vessel occlusion of the anterior circulation treated by thrombectomy. Post-reperfusion digital subtraction angiography was reviewed to look for EVF as evidenced by the contrast opacification of any cerebral vein before the late arterial phase. Results: EVF occurred in 22.4% of the 147 cases included. The presence of EVF significantly increased the risk of RPH (p = 0.0048), including the risk of symptomatic hemorrhage (p = 0.0052). The presence of EVF (p = 0.0016) and the absence of RPH (p = 0.0021) were independently associated with a better outcome as defined by the NIHSS difference at 24 h, most significantly in the EVF⁺RPH^- group. No significant relationship was however found between either EVF or RPH and a mRS score ≤ 2 at 90 days. Conclusion: Early venous filling on angiographic imaging is a potential predictor of reperfusion hemorrhage. The absence of subsequent RPH in this sub-group is associated with better outcomes at 24 h post-thrombectomy than in those with RPH.

Combined Perfusion and Permeability Imaging Reveals Different Pathophysiologic Tissue Responses After Successful Thrombectomy

Despite successful recanalization of large-vessel occlusions in acute ischemic stroke, individual patients profit to a varying degree. Dynamic susceptibility-weighted perfusion and dynamic T1-weighted contrast-enhanced blood-brain barrier permeability imaging may help to determine secondary stroke injury and predict clinical outcome. We prospectively performed perfusion and permeability imaging in 38 patients within 24 h after successful mechanical thrombectomy of an occlusion of the middle cerebral artery M1 segment. Perfusion alterations were evaluated on cerebral blood flow maps, blood-brain barrier disruption (BBBD) visually and quantitatively on k_trans maps and hemorrhagic transformation on susceptibility-weighted images. Visual BBBD within the DWI lesion corresponded to a median k_trans elevation (IQR) of 0.77 (0.41–1.4) min⁻¹ and was found in all 7 cases of hypoperfusion (100%), in 10 of 16 cases of hyperperfusion (63%), and in only three of 13 cases with unaffected perfusion (23%). BBBD was significantly associated with hemorrhagic transformation (p < 0.001). While BBBD alone was not a predictor of clinical outcome at 3 months (positive predictive value (PPV) = 0.8 [0.56–0.94]), hypoperfusion occurred more often in patients with unfavorable clinical outcome (PPV = 0.43 [0.10–0.82]) compared to hyperperfusion (PPV = 0.93 [0.68–1.0]) or unaffected perfusion (PPV = 1.0 [0.75–1.0]). We show that combined perfusion and permeability imaging reveals distinct infarct signatures after recanalization, indicating the severity of prior ischemic damage. It assists in predicting clinical outcome and may identify patients at risk of stroke progression.

Angiographic early hyperemia in the middle cerebral artery territory after thrombectomy is associated with favorable clinical outcome in anterior circulation stroke

OBJECTIVES

Angiographic cortical early hyperemia (EH) is frequently observed after endovascular thrombectomy (EVT) for large vessel occlusion (LVO) stroke. The aim of the study is to investigate the relationship between EH and clinical outcomes.

METHODS

Between January 2015 and September 2018, consecutive patients who underwent EVT for anterior circulation LVO stroke with optimal recanalization (modified thrombolysis in cerebral infarction 2b or 3) were included. Angiographic studies after immediate reperfusion were used for analysis for cortical EH sign. Clinical functional outcomes were evaluated with the modified Rankin Scale (mRS) at 90 days. Safety outcomes, including mortality and intracerebral hemorrhage, were assessed. The association of EH between clinical functional and safety outcomes was analyzed.

RESULTS

A total of 143 patients were analyzed (mean age: 71 years; median National Institutes of Health Stroke Scale score: 18). A positive EH sign was observed in 88 (62%) patients. Good functional outcome at 90 days was significantly different between the EH⁺ and EH^- groups (p = .0157). Intracerebral hemorrhage and mortality did not differ between groups. In multivariate logistic regression analysis, EH was an independent predictor for good clinical outcome (mRS ≤ 2, odds ratio: 3.49, p = .0034) in addition to young age.

CONCLUSION

Results revealed that the presence of EH is associated with better clinical outcome at 90 days, but not associated with increased hemorrhagic complication. These findings with clinically relevant implications require further validation.

KEY POINTS

• Angiographic cortical hyperemia is a common finding immediately after endovascular thrombectomy. • Presence of cortical hyperemia is an independent prognostic factor for good clinical outcome. • Hemorrhagic complication is not associated with cortical hyperemia.

Hyperperfusion on Arterial Spin Labeling MRI Predicts the 90-Day Functional Outcome After Mechanical Thrombectomy in Ischemic Stroke

BACKGROUND

The prognostic significance of hyperperfusion after reperfusion therapy in patients with acute ischemic stroke (AIS) remains controversial.

PURPOSE

To investigate the clinical factors associated with hyperperfusion, and the 90-day prognostic value of hyperperfusion after mechanical thrombectomy in AIS patients.

STUDY TYPE

Retrospective.

POPULATION/SUBJECTS

Fifty-four AIS patients who underwent mechanical thrombectomy.

FIELD STRENGTH/SEQUENCE

Time-of-flight MR angiography, pulsed arterial spin labeling (ASL), diffusion-weighted imaging (DWI), and susceptibility-weighted imaging were performed at 3.0T within 1 week after thrombectomy.

ASSESSMENT

Clinical factors including demographics, risk factors, stroke and treatment characteristics were collected and assessed. Hyperperfusion on ASL was defined as a focal increased cerebral blood flow on the affected side ≥130% of its mirror counterpart. Good clinical outcome at 90 days was defined as modified Rankin Scale score of 0-2.

STATISTICAL TESTS

The interrater agreement was assessed using Cohen's kappa or the intraclass correlation coefficient. The relationship between hyperperfusion and clinical factors were analyzed by appropriate univariate statistics. Predictors of 90-day functional outcome were assessed by univariate analyses followed by multivariate logistic regression analysis and receiver-operating-characteristic curves.

RESULTS

Thirty-six (66.7%) patients developed hyperperfusion on ASL after thrombectomy. Hyperperfusion was significantly correlated with successful recanalization (P < 0.05) and improvement of National Institutes of Health Stroke Scale scores at 24 hours (NIHSS_24h ) (P < 0.05). A higher incidence of hemorrhage transformation was observed in patients with hyperperfusion than those without (63.9% vs. 50.0%), but no significant difference was found (P = 0.327). NIHSS_24h (odds ratio [OR], 0.75, [95% confidence interval [CI] 0.62-0.91], P < 0.05), lesion volume on diffusion-weighted imaging (OR, 0.97, [95% CI 0.95-1.00], P < 0.05), and hyperperfusion on ASL (OR, 9.8, [95% CI 1.7-55.3], P < 0.05) were independent variables for predicting good functional outcomes.

DATA CONCLUSION

Hyperperfusion on ASL correlated with successful recanalization and may be an independent prognostic marker for good neurological outcomes at 90 days in AIS patients after mechanical thrombectomy.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY STAGE: 2.

What predicts poor outcome after successful thrombectomy in late time windows?

BACKGROUND

Thrombectomy for acute ischemic stroke treatment leads to improved outcomes, but many patients do not achieve a good outcome despite successful reperfusion. We determined predictors of poor outcome after successful thrombectomy (TICI 2b-3) with an emphasis on modifiable factors.

METHODS

Patients from the randomized DEFUSE 3 trial who underwent thrombectomy with TICI 2b-3 revascularization were included. Primary outcome was a poor outcome at 90 days (modified Rankin Scale score 3-6).

RESULTS

70 patients were included. Poor outcome patients were older (73.5 vs 66.5 years; P=0.01), more likely to be female (68% vs 39%; P=0.02), had higher NIHSS scores (20 vs 13; P<0.001), and had poor cerebral perfusion collaterals (hypoperfusion intensity ratio) (median 0.45 vs 0.38; P=0.03). Following thrombectomy, poor outcome patients had larger 24 hour' core infarctions (median 59.5 vs 29.9 mL; P=0.01), more core infarction growth (median 33.6 vs 13.4 mL; P<0.001), and more mild (65% vs 50%; P=0.02) and severe (18% vs 0%; P=0.01) reperfusion hemorrhage. In a logistic regression analysis, the presence of any reperfusion hemorrhage (OR 3.3 [95% CI, 1.67 to 5]; P=0.001), age (OR 1.1 [95% CI, 1.03 to 1.11], P=0.004), higher NIHSS (OR 1.25 [95% CI, 1.07 to 1.41], P=0.002), and time from imaging to femoral artery puncture (OR 5 [95% CI, 1.16 to 16.67], P=0.03) independently predicted poor outcomes.

CONCLUSIONS

In late time windows, both mild and severe reperfusion hemorrhage were associated with poor outcomes. Older age, higher NIHSS, and increased time from imaging to arterial puncture were also associated with poor outcomes despite successful revascularization.

TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT02586415.

Update on cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome (CHS) is a clinical syndrome following a revascularization procedure. In the past decade, neurointerventional surgery has become a standard procedure to treat stenotic or occluded cerebral vessels in both acute and chronic settings, as well as endovascular thrombectomy in acute ischemic stroke. This review aims to summarize relevant recent studies regarding the epidemiology, diagnosis, and management of CHS as well as to highlight areas of uncertainty. Extracranial and intracranial cerebrovascular diseases in acute and chronic conditions are considered. The definition and diagnostic criteria of CHS are diverse. Although impaired cerebrovascular autoregulation plays a major role in the pathophysiology of CHS, the underlying mechanism is still not fully understood. Its clinical characteristics vary in different patients. The current findings on clinical and radiological presentation, pathophysiology, incidence, and risk factors are based predominantly on carotid angioplasty and stenting studies. Hemodynamic assessment using imaging modalities is the main form of diagnosis although the criteria are distinct, but it is helpful for patient selection before an elective revascularization procedure is conducted. After endovascular thrombectomy, a diagnosis of CHS is even more complex, and physicians should consider concomitant reperfusion injury. Management and preventative measures, including intensive blood pressure control before, during, and after revascularization procedures and staged angioplasty, are discussed in detail.

Transcranial contrast-enhanced ultrasound in the rat brain reveals substantial hyperperfusion acutely post-stroke

Direct and real-time assessment of cerebral hemodynamics is key to improving our understanding of cerebral blood flow regulation in health and disease states such as stroke. While a number of sophisticated imaging platforms enable assessment of cerebral perfusion, most are limited either spatially or temporally. Here, we applied transcranial contrast-enhanced ultrasound (CEU) to measure cerebral perfusion in real-time through the intact rat skull before, during and after ischemic stroke, induced by intraluminal filament middle cerebral artery occlusion (MCAO). We demonstrate expected decreases in cortical and striatal blood volume, flow velocity and perfusion during MCAO. After filament retraction, blood volume and perfusion increased two-fold above baseline, indicative of acute hyperperfusion. Adjacent brain regions to the ischemic area and the contralateral hemisphere had increased blood volume during MCAO. We assessed our data using wavelet analysis to demonstrate striking vasomotion changes in the ischemic and contralateral cortices during MCAO and reperfusion. In conclusion, we demonstrate the application of CEU for real-time assessment of cerebral hemodynamics and show that the ischemic regions exhibit striking hyperemia post-MCAO. Whether this post-stoke hyperperfusion is sustained long-term and contributes to stroke severity is not known.

Imaging After Thrombolysis and Thrombectomy: Rationale, Modalities and Management Implications

PURPOSE OF REVIEW

Urgent reperfusion treatment with intravenous thrombolysis or mechanical thrombectomy reduces disability after ischaemic stroke. Imaging plays an important role in identifying patients who benefit, particularly in extended time windows. However, the role of post-treatment neuroimaging is less well established. We review recent advances in neuroimaging after reperfusion treatment and provide a practical guide to the options and management implications.

RECENT FINDINGS

Post-treatment imaging is critical to identify patients with reperfusion-related haemorrhage and oedema requiring intervention. It also can guide the timing and intensity of antithrombotic medication. The degree of reperfusion on post-thrombectomy angiography and infarct volume and topography using CT or MRI carry important prognostic significance. Perfusion-weighted MRI and permeability analysis may help detect persistent perfusion abnormalities post-treatment and predict haemorrhagic complications. Post-treatment neuroimaging provides clinically relevant information to identify complications, assess prognosis and perform quality assurance after acute ischaemic stroke. Recent advances in neuroimaging represent a potential avenue to explore post-reperfusion pathophysiology and uncover therapeutic targets for secondary ischaemic and haemorrhagic injury.