Seong-Joon Lee

Cerebral Arterial Calcification Is an Imaging Prognostic Marker for Revascularization Treatment of Acute Middle Cerebral Arterial Occlusion

Background and Purpose To study the significance of intracranial artery calcification as a prognostic marker for acute ischemic stroke patients undergoing revascularization treatment after middle cerebral artery (MCA) trunk occlusion. Methods Patients with acute MCA trunk occlusion, who underwent intravenous and/or intra-arterial revascularization treatment, were enrolled. Intracranial artery calcification scores were calculated by counting calcified intracranial arteries among major seven arteries on computed tomographic angiography. Patients were divided into high (HCB; score ≥3) or low calcification burden (LCB; score <3) groups. Demographic, imaging, and outcome data were compared, and whether HCB is a prognostic factor was evaluated. Grave prognosis was defined as modified Rankin Scale 5-6 for this study. Results Of 80 enrolled patients, the HCB group comprised 15 patients, who were older, and more commonly had diabetes than patients in the LCB group. Initial National Institutes of Health Stroke Scale (NIHSS) scores did not differ (HCB 13.3±2.7 vs. LCB 14.6±3.8) between groups. The final good reperfusion after revascularization treatment (thrombolysis in cerebral infarction score 2b-3, HCB 66.7% vs. LCB 69.2%) was similarly achieved in both groups. However, the HCB group had significantly higher NIHSS scores at discharge (16.0±12.3 vs. 7.9±8.3), and more frequent grave outcome at 3 months (57.1% vs. 22.0%) than the LCB group. HCB was proven as an independent predictor for grave outcome at 3 months when several confounding factors were adjusted (odds ratio 4.135, 95% confidence interval, 1.045-16.359, P=0.043). Conclusions Intracranial HCB was associated with grave prognosis in patients who have undergone revascularization for acute MCA trunk occlusion.

Distinctive patterns on CT angiography characterize acute internal carotid artery occlusion subtypes.

Abstract Noninvasive computed tomography angiography (CTA) is widely used in acute ischemic stroke, even for diagnosing various internal carotid artery (ICA) occlusion sites, which often need cerebral digital subtraction angiography (DSA) confirmation. We evaluated whether clinical outcomes vary depending on the DSA-based occlusion sites and explored correlating features on baseline CTA that predict DSA-based occlusion site. We analyzed consecutive patients with acute ICA occlusion who underwent DSA and CTA. Occlusion site was classified into cervical, cavernous, petrous, and carotid terminus segments by DSA confirmation. Clinical and radiological features associated with poor outcome at 3 months (3–6 of modified Rankin scale) were analyzed. Baseline CTA findings were categorized according to carotid occlusive shape (stump, spearhead, and streak), presence of cervical calcification, Willisian occlusive patterns (T-type, L-type, and I-type), and status of leptomeningeal collaterals (LMC). We identified 49 patients with occlusions in the cervical (n = 17), cavernous (n = 22), and carotid terminus (n = 10) portions: initial NIH Stroke Scale (11.4 ± 4.2 vs 16.1 ± 3.7 vs 18.2 ± 5.1; P < 0.001), stroke volume (27.9 ± 29.6 vs 127.4 ± 112.6 vs 260.3 ± 151.8 mL; P < 0.001), and poor outcome (23.5 vs 77.3 vs 90.0%; P < 0.001). Cervical portion occlusion was characterized as rounded stump (82.4%) with calcification (52.9%) and fair LMC (94.1%); cavernous as spearhead occlusion (68.2%) with fair LMC (86.3%) and no calcification (95.5%); and terminus as streak-like occlusive pattern (60.0%) with poor LMC (60.0%), and no calcification (100%) on CTA. Our study indicates that acute ICA occlusion can be subtyped into cervical, cavernous, and terminus. Distinctive findings on initial CTA can help differentiate ICA-occlusion subtypes with specific characteristics.

Erythrocyte Fraction Within Retrieved Thrombi Contributes to Thrombolytic Response in Acute Ischemic Stroke

Background and Purpose— Recent advent of endovascular thrombectomy (EVT) enables us to provide a new perspective on the use of tPA (tissue-type plasminogen activator) through histological analysis of retrieved thrombus. We investigated the responsiveness of intravenous thrombolysis (IVT) according to the thrombus composition in EVT-attempted patients with acute ischemic stroke. Methods— We reviewed 92 consecutive patients with anterior circulation stroke who received combined IVT and EVT for 2 years. IVT responsiveness is defined as any decrease in the clot burden from baseline computed tomographic angiography to digital subtraction angiography during EVT. We histologically analyzed the relative fractions of red blood cells (RBCs), congregated fibrin and platelets, and white blood cells in the retrieved thrombi using semiautomated color-based segmentation method. Clinical characteristics according to the RBC fraction were investigated, and associated factors with IVT responsiveness were explored. Results— Fifty-two patients with histological analyses were stratified into lowest, middle, and highest tertiles of RBC fraction. Toward higher RBC fraction, there was more common susceptibility vessel signs on magnetic resonance imaging (50.0% versus 66.7% versus 91.7%; P=0.022) and prevalent IVT responsiveness (25.0% versus 41.7% versus 75.0%; P=0.010). IVT-responsive group (n=23) had higher RBC fraction (45.7±15.5% versus 35.9±12.2%; P=0.010), lower fibrin and platelet (50.4±14.0% versus 58.5±11.1%; P=0.027), and lower white blood cells fraction (3.9±2.1% versus 5.5±3.0%; P=0.027) than IVT-unresponsive group (n=29). After adjusting for potential variables, RBC fraction (odds ratio, 1.05; 95% confidence interval, 1.01–1.10) remained only independent determinant of IVT responsiveness. Conclusions— In EVT-attempted patients with acute ischemic stroke, IVT responsiveness would be closely associated with RBC fraction.

Temporal Changes in Care Processes and Outcomes for Endovascular Treatment of Acute Ischemic Stroke: Retrospective Registry Data from Three Korean Centers

Background and Purpose The purpose of the current study is to evaluate the influence of temporal patterns related to the availability of new endovascular treatment (EVT) devices on care processes and outcomes among patients with AIS. Materials and Methods We enrolled 720 consecutive patients (January 2011 to May 2016) in a retrospective registry, ASIAN KR, from three Korean hospitals, who received EVT for acute ischemic stroke (AIS) caused by cervicocephalic arterial occlusions. We performed period-to-period analyses based on stent retriever reimbursement and the availability of second-generation direct-aspiration devices (Period 1: January 2011–July 2014 vs. Period 2: August 2014–May 2016); time metrics and outcomes were compared when the onset-to-puncture time was <720 min among patients with EVT for intracranial occlusion. Results Period 2 had better post-EVT outcomes (3-month modified Rankin Scale 0–2 or equal to prestroke score, 48.3% vs. 60.2%, P=0.004), more successful reperfusion rates (modified Treatment In Cerebral Ischemia 2b–3, 74.2% vs. 82.2%, P=0.019), fewer subarachnoid hemorrhages (modified Fisher grade 3–4, 5.5% vs. 2.0%, P=0.034) and lower hemorrhagic transformation rates (any intracerebral hemorrhage, 35.3 vs. 22.7%, P=0.001) than Period 1. Compared to Period 1, Period 2 had a shorter door-to-puncture time (median 109 vs. 90 min, P<0.001), but longer onset-to-door time (129 vs. 143 min, P=0.057). Conclusion Recent temporal improvements in post-EVT AIS outcomes in Korea are likely due to a combination of enhanced hospital care processes and administration of newer thrombectomy devices.

Electronic Band Alignment at Complex Oxide Interfaces Measured by Scanning Photocurrent Microscopy

The band alignment at an Al2O3/SrTiO3 heterointerface forming a two-dimensional electron gas (2DEG) was investigated using scanning photocurrent microscopy (SPCM) in an electrolyte-gated environment. We used a focused UV laser source for above-the-bandgap illumination on the SrTiO3 layer, creating electron-hole pairs that contributed to the photocurrent through migration towards the metal electrodes. The polarity of the SPCM signals of a bare SrTiO3 device shows typical p-type behavior at zero gate bias, in which the photogenerated electrons are collected by the electrodes. In contrast, the SPCM polarity of 2DEG device indicates that the hole carriers were collected by the metal electrodes. Careful transport measurements revealed that the gate-dependent conductance of the 2DEG devices exhibits n-type switching behavior. More importantly, the SPCM signals in 2DEG devices demonstrated very unique gate-responses that cannot be found in conventional semiconducting devices, based on which we were able to perform detailed investigation into the electronic band alignment of the 2DEG devices and obtain the valence band offset at the heterointerface.

Card-placing test in amnestic mild cognitive impairment and its neural correlates.

BackgroudWe investigated anatomical correlates of the card-placing test (CPT) in patients with amnestic mild cognitive impairment (aMCI).MethodsFifteen aMCI patients underwent part A and part B of the CPT and FDG-PET. The CPT scores and MMSE scores of 29 cognitively normal people were used for comparison. Statistical parametric mapping (SPM) correlation analysis was used to extract the regions whose changes in regional cerebral metabolism correlated significantly with part A and B of the CPT with adjustment of age, education and sex of patients.ResultsThe aMCI patients had significantly lower MMSE scores (26.0 ± 2.0 vs. 28.2 ± 1.4, p < 0.001), CPT A (25.5 ± 3.5 vs. 27.7 ± 2.7, p = 0.026) and CPT B scores (16.3 ± 4.4 vs. 19.7 ± 3.7, p = 0.011) compared to the normal population. The test scores of part B of the CPT correlated well with hypometabolism of the posterior cingulate gyrus and precuneus.ConclusionsThis study suggests that the CPT B may reflect the functional status of the posterior cingulate gyrus in patients with aMCI.

Feasibility of Multiple Burr Hole With Erythropoietin in Acute Moyamoya Patients

Background and Purpose— In patients with acute symptomatic moyamoya (<2 weeks), the feasibility of a combination therapy of multiple burr hole procedure under local anesthesia and intravenous erythropoietin pretreatment was assessed. We also identified the factors associated with transdural revascularization. Methods— In this prospective single-arm study, perfusion-impaired patients presenting with transient ischemic attack or acute cerebral infarction were assessed. Combination therapy was performed to patients lacking transdural collaterals. Primary outcomes were evaluated clinically with modified Rankin Scale scores and radiologically with revascularization success (transhemispheric, trans-burr hole, and sufficient revascularizations [filling ≥33% of ipsilateral supratentorium]) at 6 months. Treatment-related adverse events were analyzed in 3 phases: pre burr hole, post burr hole, and after-discharge as secondary outcome. Factors associated with sufficient revascularization were investigated. Results— Fifty hemispheres from 37 patients were included. Compared with discharge, modified Rankin Scale score at 6 months significantly improved (2.0 [0.0–5.0] versus 1.0 [0.0–4.0]; P<0.001). Majority had successful revascularization: trans-burr hole arteriogenesis (89.5%), transhemispheric arteriogenesis (98.0%), and sufficient revascularization (52.0%). There was no significant pre burr hole or post burr hole complication. Two (5.4%) transient ischemic attack and 1 (2.7%) cerebral infarction occurred after discharge. Presentation with acute infarction (odds ratio, 4.8; 95% confidence interval, 1.1–21.4), ipsilateral basal moyamoya vessels (odds ratio, 13.9; 95% confidence interval, 1.3–144.2), and delayed mean transit time (odds ratio, 3.9; 95% confidence interval, 1.3–12.2) predicted sufficient revascularization. Conclusions— Combination therapy allows safe and effective revascularization in moyamoya patients with acute ischemic presentation. Clinical Trial Registration— URL: https://www.clinicaltrials.gov. Unique identifier: NCT03162588.

Impact of varying levels of hyperglycemia on clinicoradiographic outcomes after endovascular reperfusion treatment

We evaluated the effects of admission hyperglycemia with different cut-off levels on 3-month outcomes, infarct growth, and hemorrhagic transformation in acute stroke patients with large artery occlusion of anterior circulation who received endovascular treatment (EVT). Between January 2011 and May 2016, patients that underwent EVT with pre-procedural and post-procedural diffusion-weighted imaging were identified from a multicenter registry. Normoglycemia was defined as a glucose level ≤ 110 mg/dL, moderate hyperglycemia as >110 and ≤170 mg/dL, and overt hyperglycemia as >170 mg/dL. Its effects on poor outcomes (3-month modified Rankin Scale score 3–6), infarct growth, and parenchymal hematoma type 2 were analyzed. Of 720 patients encountered, 341 patients were eligible. There was a statistically significant difference in glycated hemoglobin levels between the normoglycemia/moderate hyperglycemia and overt hyperglycemia groups (p < 0.001). Moderate hyperglycemia (odds ratio 2.37 [95% confidence interval 1.26–4.45], p = 0.007) and overt hyperglycemia (2.84 [1.19–6.81], p = 0.019) were associated with poor outcomes. Post-procedural infarct volumes were significantly greater in hyperglycemic patients (padjusted = 0.003). Only overt hyperglycemia (9.28 [1.66–51.88], p = 0.011) was associated with parenchymal hematoma type 2. Overall hyperglycemia was associated with poor outcomes and infarct growth, whereas overt hyperglycemia was associated with parenchymal hematoma type 2.

Central and cerebral haemodynamic changes after antihypertensive therapy in ischaemic stroke patients: A double-blind randomised trial

Central and cerebral haemodynamic parameters can vary under similar brachial blood pressure (BP). We aimed to investigate the effects of antihypertensive agents on central and cerebral haemodynamic parameters in hypertensive patients with ischaemic stroke. The Fimasartan, Atenolol, and Valsartan On haemodynamic paRameters (FAVOR) study was conducted in a prospective, double-blinded manner. One hundred five patients were randomly administered atenolol, valsartan, or fimasartan during 12 weeks. We measured brachial, central, cerebral haemodynamic parameters and plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) levels at baseline and after 12-week. Baseline haemodynamic parameters were balanced among the three groups. Even with similar brachial BP reduction, significantly lower central systolic BP (atenolol; 146.5 ± 18.8 vs. valsartan; 133.5 ± 20.7 vs. fimasartan; 133.6 ± 19.8 mmHg, p = 0.017) and augmentation index values (89.8 ± 13.2 vs. 80.6 ± 9.2 vs. 79.2 ± 11.6%; p = 0.001) were seen in the angiotensin receptor blockers (ARBs) groups. The pulsatility index on transcranial Doppler was significantly reduced in valsartan (p = 0.002) and fimasartan group (p = 0.008). Plasma NT-proBNP level was also significantly decreased in ARB groups, especially for the fimasartan group (37.8 ± 50.6 vs. 29.2 ± 36.9 vs.19.2 ± 27.8 pg/mL; p = 0.006). These findings suggest that short-term ARB administration would be favourable for ischaemic stroke patients with hypertension, permitting effective reduction of central pressure and dampening of cerebral pulsatility.

Prognosis of Acute Intracranial Atherosclerosis-Related Occlusion after Endovascular Treatment

Background and Purpose Little is known about prognosis after endovascular therapy (EVT) for acute large artery occlusion (LAO) caused by underlying intracranial atherosclerotic stenosis (ICAS). Therefore, we investigated the prognosis following EVT according to the underlying etiology of LAO. Methods Patients from the Acute Stroke due to Intracranial Atherosclerotic occlusion and Neurointervention-Korean Retrospective (ASIAN KR) registry (n=720) were included if their occlusion was in the intracranial anterior circulation and their onset-to-puncture time was <24 hours. Occlusion was classified according to etiology as follows: no significant stenosis after recanalization (Embolic group), and fixed significant focal stenosis in the occlusion site with flow impairment or re-occlusion observed during EVT (ICAS group). Patients were excluded when significant extracranial carotid lesions existed, and when the intracranial occlusion was intractable to EVT so that the etiology was undetermined. The effect of angiographic etiologic classification on outcomes was evaluated using multivariable analysis that was adjusted for potential confounders. Results Among eligible patients (n=520), 421 and 99 were classified in the Embolic and ICAS groups, respectively. Patients in the Embolic and ICAS groups had similar successful reperfusion rates with EVT (79.6% vs. 76.8%, P=0.537) and 3-month functional independence (54.5% vs. 45.5%, P=0.104). In multivariable analysis, ICAS-related occlusion (odds ratio, 0.495; 95% confidence interval, 0.269 to 0.913; P=0.024) showed poorer 3-month functional independence compared to embolic occlusion. Conclusions After EVT, patients with acute ICAS-related occlusion have relatively poor functional outcomes compared to those with embolic occlusion. Novel strategies need to be developed to improve EVT outcomes for ICAS occlusion.