Modified ASPECTS for DWI including deep white matter lesions predicts subsequent intracranial hemorrhage

Non-contrast dual-energy CT using X-map for acute ischemic stroke: region-specific comparison with simulated 120-kVp CT and diffusion-weighted MR images

PURPOSE

X-map is a non-contrast dual-energy CT (DECT) application to identify acute ischemic stroke (AIS). Our aim was to verify region-specific characteristics of early ischemic changes (EIC) on X-map compared with simulated 120-kVp mixed-CT image and DWI.

METHODS

Fifty AIS patients who underwent DECT and DWI were enrolled (mean age, 76 years; 34 men, 16 women). All datasets including mixed-CT image, X-map, and DWI were transformed into a standard brain atlas with 11 × 2 ROIs based on the ASPECTS + W system. ROIs with EIC on DWI, mixed-CT image, and X-map were defined as DWI-positive, mixed-CT-positive, and X-map-positive, and those with normal finding were DWI-negative, mixed-CT-negative, and X-map-negative respectively, in visual assessment by two neuroradiologists in consensus.

RESULTS

EIC on X-maps were visually relevant to those on the other images: of 221 ROIs with mixed-CT-positive and X-map-positive, 198 (89.6%) were DWI-positive. X-map revealed moderate diagnostic accuracy for AIS compared with DWI in ROC curve analysis (AUC = 0.732). X-map identified EIC in deep white matter more sensitively than mixed-CT image: of 15 ROIs with mixed-CT-negative and X-map-positive in W segments, 14 (93.3%) were DWI-positive. X-map often showed EIC in cortical regions that were not detected on the other images: of 67 ROIs with mixed-CT-negative and X-map-positive in I and M1-M6 segments, 47 (70.1%) were DWI-negative.

CONCLUSIONS

X-map is useful to detect EIC, especially in deep white matter, and may also provide additional information in acute ischemic lesions where DWI cannot be detected.

Minimal Imaging Requirements

The minimal requirements for imaging studies prior to endovascular treatment (EVT) of acute ischemic stroke are those that can provide the information necessary to determine the indication for treatment (treatment triage) and procedural strategies without being time-consuming. An important notion is to determine whether the patient can benefit from EVT. We should recognize that the perfect diagnostic imaging technique does not yet exist, and each has advantages and disadvantages. Generally, stroke imaging protocols to triage for EVT include the following three options: 1) non-contrast CT and CTA, 2) CT perfusion and CTA, and 3) MRI and MRA. It is not known if perfusion imaging or MRI is mandatory for patients with stroke presenting within 6 hours of onset, although non-contrast CT alone has less power to obtain the necessary information. Dual-energy CT can distinguish between post-EVT hemorrhage and contrast agent leakage immediately after EVT.

Automatic comprehensive aspects reports in clinical acute stroke MRIs

The Alberta Stroke Program Early CT Score (ASPECTS) is a simple visual system to assess the extent and location of ischemic stroke core. The capability of ASPECTS for selecting patients' treatment, however, is affected by the variability in human evaluation. In this study, we developed a fully automatic system to calculate ASPECTS comparable with consensus expert readings. Our system was trained in 400 clinical diffusion weighted images of patients with acute infarcts and evaluated with an external testing set of 100 cases. The models are interpretable, and the results are comprehensive, evidencing the features that lead to the classification. This system adds to our automated pipeline for acute stroke detection, segmentation, and quantification in MRIs (ADS), which outputs digital infarct masks and the proportion of diverse brain regions injured, in addition to the predicted ASPECTS, the prediction probability and the explanatory features. ADS is public, free, accessible to non-experts, has very few computational requirements, and run in real time in local CPUs with a single command line, fulfilling the conditions to perform large-scale, reproducible clinical and translational research.

The association between the severity and distribution of white matter lesions and hemorrhagic transformation after ischemic stroke: A systematic review and meta-analysis

Background and purpose

As a part of the natural course of ischemic stroke, hemorrhagic transformation (HT) is a serious complication after reperfusion treatment, which may affect the prognosis of patients with ischemic stroke. White matter lesions (WMLs) refer to focal lesions on neuroimaging and have been suggested to indicate a high risk of HT. This systematic review and meta-analysis aimed to summarize current evidence on the relation between WML and HT.

Methods

This systematic review was prepared with reference to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched PubMed, Embase, Web of Science, and Cochrane Library databases for publications on WML and HT in patients with ischemic stroke. Odds ratios (ORs) and 95% confidence intervals (CIs) from eligible studies were combined to quantify the association between the severity of WML and the risk of HT. In addition, the descriptive analysis was adopted to evaluate the influence of different WML distributions on predicting HT.

Results

A total of 2,303 articles were identified after removing duplicates through database searching, and 41 studies were included in our final analysis. The meta-analysis showed that the presence of WML was associated with HT (OR = 1.62, 95%CI 1.08-2.43, p = 0.019) and symptomatic intracerebral hemorrhage (sICH) (OR = 1.64, 95%CI 1.17-2.30, p = 0.004), and moderate-to-severe WML indicated a high risk of HT (OR = 2.03, 95%CI 1.33-3.12, p = 0.001) and sICH (OR = 1.92, 95%CI 1.31-2.81, p < 0.001). The dose-response meta-analysis revealed risk effects of increasing the severity of WML on both HT and ICH. In addition, both periventricular WML (PWML) (five of seven articles) and deep WML (DWML) (five of six articles) were shown to be associated with HT.

Conclusions

White matter lesions are associated with overall HT and sICH in patients with ischemic stroke, and more severe WMLs indicate a high risk of HT and sICH. In addition, both PWML and DWMLs could be risk factors for HT.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: PROSPERO CRD42022313467.

[A case of recurrent cerebral embolism associated with Lambl's excrescence]

A 75-year-old female had a history of prior ischemic stroke with aphasia and right hemiplegia. Magnetic resonance angiography showed left internal carotid artery occlusion. She was successfully treated with intravenous recombinant tissue plasminogen activator (IV t-PA) and underwent endovascular thrombectomy (EVT). She was diagnosed with cardioembolic stroke due to the presence of atrial fibrillation and mitral valve stenosis, and warfarin was administered. However, she experienced large vessel occlusion twice within 2 years. Upon further analysis, transesophageal echocardiography revealed a mobile hyperechoic structure on the aortic valve, which was assumed to be an embolic source. Thus, we decided to perform mitral and aortic valve replacement. The excised aortic valve structure was suggested to be an example of Lambl's excrescence, histopathologically. After surgery, the patient had no recurrence for 3 years. Several cases of ischemic stroke associated with Lambl's excrescence have been reported, but definitive guidelines for managing patients with Lambl's excrescence do not currently exist. Surgical intervention for Lambl's excrescence with recurrent ischemic events may be important for preventing further recurrence.

Acute Thrombectomy for Contralateral Internal Carotid Artery Occlusion after Revascularization Surgery for Quasi-moyamoya Disease: A Case Report

Ischemic complications can occur after revascularization surgery for moyamoya disease, but acute contralateral internal carotid artery (ICA) occlusion is an extremely rare complication. The patient was a 51-year-old woman with no medical history. Left frontal lobe infarction and bilateral ICA terminal stenosis were identified by repeated transient right paresis and aphasia. We diagnosed her with quasi-moyamoya disease associated with hyperthyroidism and performed revascularization surgery for the symptomatic left side. Although neurological symptoms did not worsen immediately after the surgery, disturbance of consciousness, right conjugate deviation, and left paresis appeared 4 hr after the surgery. New infarction appeared in the right frontal lobe, and the blood signal beyond the right middle cerebral artery (MCA) disappeared on MRI and MRA. Mechanical thrombectomy (MT) using a suction catheter improved antegrade blood flow in the MCA. The left paresis remained at discharge (modified Rankin Scale score = 4), but she was able to walk independently 3 months after the operation and was independent at home. Acute contralateral ICA occlusion after revascularization for moyamoya disease is an extremely rare complication, but the symptoms can be severe and treatment should be considered. To the best of our knowledge, there have been no reports of MT for postoperative acute contralateral ICA occlusion. Since the results of endovascular treatment such as percutaneous transluminal angioplasty and stent placement for patients with moyamoya disease are poor, MT using an aspiration catheter could be a good treatment option.

Anticoagulation Protocol for Secondary Prevention of Acute Ischemic Stroke Associated with Nonvalvular Atrial Fibrillation

OBJECTIVES

There is no clear evidence regarding when to initiate oral anticoagulants (OACs) for secondary prevention of recurrent stroke in patients with atrial fibrillation (AF). Therefore, this study aimed to evaluate the safety and efficacy of a novel OAC initiation protocol for secondary prevention of acute ischemic stroke associated with AF.

MATERIALS AND METHODS

In this multicenter prospective study 597 consecutive Japanese patients with acute ischemic stroke associated with nonvalvular AF received post-stroke OACs according to a protocol based on severity (clinical (NIHSS) and radiological (ASPECTS + W)), rt-PA use, reperfusion, and hemorrhagic transformation (HT). Primary outcomes of safety and efficacy, including symptomatic hemorrhage, cerebral stroke, and disability were evaluated at 14 and 90 days.

RESULTS

Mean OAC initiation time was 2.60±2.14 days from onset. The shortest and longest mean initiation times were 0.47±0.50 and 6.16±0.72 days, respectively. Following OAC administration, no ICH was observed within 90 days. A significantly higher incidence of acute recurrent ischemic events occurred 14 days prior to OAC (4.7%) compared with chronic recurrence within 90 days (0.8%) (P = 0.00013, McNemar's test) . Recurrence prior to OAC use was significantly correlated with days to treatment (P = 0.00224), severity (NIHSS, ASPECTS+W: P = 0.0223, P = 0.0393, respectively), and HAS-BLED (P = 0.0395) and there were no correlations with CHADS₂ (P = 0.277) or CHA₂DS₂-VASc (P = 0.246) (Wilcoxon rank sum-test).

CONCLUSIONS

This comprehensive OAC initiation protocol was relatively safe and effective for secondary prevention of stroke in patients with AF. Risk of acute recurrence was high, indicating that OACs should be started as early as possible. (clinical trial registration number: 15B 128).

ASPECTS-Region-Dependent Functional Outcomes after Endovascular Therapy in Patients with Cardioembolic Stroke

OBJECTIVES

Cardioembolic stroke has a poor prognosis. We evaluated the region-dependent efficacy of endovascular therapy (EVT) based on diffusion-weighted imaging-Alberta Stroke Program Early CT Score (DWI-ASPECTS).

METHODS

This post-hoc analysis of the RELAXED study, which investigated the optimal timing of rivaroxaban to prevent nonvalvular atrial fibrillation (NVAF) recurrence in patients with acute ischemic stroke (AIS), included NVAF patients admitted with AIS or transient ischemic attack in the middle cerebral artery (MCA), with internal carotid artery (ICA), M1, or M2-MCA occlusion. Relationships between DWI-ASPECTS region and functional outcome (modified Rankin Scale [mRS]), mortality, recurrence, and hemorrhagic stroke were compared between patients with and without EVT, and adjusted odds ratios for age, pre-stroke mRS, National Institutes of Health Stroke Scale (NIHSS), ICA occlusion, infarct size, recombinant tissue plasminogen activator (rt-PA) use, and onset-to-hospitalization time were estimated.

RESULTS

EVT patients had significantly lower hemoglobin levels, higher median NIHSS scores, more lentiform nucleus infarcts, ICA or M1-MCA occlusions, treatment with rt-PA, and fewer M3, M5, or M6 infarcts and M2-MCA occlusions than no-EVT patients. EVT patients had shorter onset-to-hospitalization times and more frequent favorable functional outcomes (p=0.007). Mortality, recurrent ischemic stroke, and hemorrhagic infarction were similar in both groups. EVT was associated with significantly better functional outcomes among patients with insular ribbon (p=0.043) and M3 (p=0.0008) infarcts. M3 patients had significantly fewer rt-PA and EVT, and longer onset-to-hospitalization times.

CONCLUSIONS

An occlusion in the insular ribbon or M3 region was associated with favorable functional outcomes in patients treated with EVT after cardioembolic stroke.

Modified diffusion-weighted imaging-Alberta Stroke Program Early Computed Tomography Score including deep white matter lesions predicts symptomatic intracerebral hemorrhage following intravenous thrombolysis

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is widely used for the assessment of early ischemic changes (EICs) before thrombolysis. However, for symptomatic intracerebral hemorrhage (sICH) following intravenous recombinant tissue plasminogen activator (rt-PA), the prediction abilities of CT-ASPECTS, diffusion-weighted imaging (DWI)-ASPECTS, and DWI-ASPECTS including EICs in deep white matter (DWI-ASPECTS + W) are unclear. We investigated associations between each score and sICH following intravenous rt-PA. Data from consecutive patients who received intravenous rt-PA for acute ischemic stroke from 2005 to 2015 in four hospitals were retrospectively screened. We included data from patients who had undergone both CT and magnetic resonance imaging before thrombolysis and without evidence of posterior circulation stroke. We analyzed the ability of CT-ASPECTS, DWI-ASPECTS, and DWI-ASPECTS + W to predict sICH, accompanied by an increase in the National Institutes of Health Stroke Scale (NIHSS) score of ≥ 4 within the initial 36 h. Of 455 patients (273 men, median 75 years old), sICH occurred in 15 patients (3.3%). Receiver operating characteristics curve analysis showed that the optimal cut-offs of CT-ASPECTS, DWI-ASPECTS, and DWI-ASPECTS + W for predicting sICH were ≤ 9 (sensitivity 60.0%, specificity 59.8%, c-statistic 0.625), ≤ 6 (sensitivity 53.3%, specificity 80.9%, c-statistic 0.718), and ≤ 8 (sensitivity 86.7%, specificity 55.9%, c-statistic 0.756), respectively. A DWI-ASPECTS + W of ≤ 8 was independently associated with sICH (odds ratio 5.21, 95% confidence interval 1.30–35.31) after adjustment for pretreatment with antithrombotic agents, pretreatment NIHSS score, and large artery occlusions. DWI-ASPECTS + W predicted sICH in patients with acute anterior circulation stroke receiving intravenous rt-PA.

Clinical Evaluations of the Ischemic Core in Acute Ischemic Stroke Using Modified Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Scores by Ischemic Reversibility Using the Signal Intensity

Objective

Early recanalization of acute stroke caused by large vessel occlusion (LVO) may improve high signal intensity (HSI) on diffusion-weighted imaging (DWI). In this study, we investigated whether subtraction of reversible ischemic lesions (RIL) from the HSI lesions on DWI improves the diagnostic accuracy for the ischemic core.

Methods

A total of 35 patients from April 2013 and December 2019 were included in this study. These patients presented acute ischemic stroke due to anterior circulation LVO and underwent thrombectomy. All patients underwent DWI within 48 hours after thrombectomy. HSI ratios were calculated, and compared between ischemic lesions and contralateral normal tissue. Ischemic lesions with improvement in the HSI ratio from initial to postoperative DWI were defined as RIL. Based on a receiver operating characteristic (ROC) curve analysis that compared the HSI ratio of all ischemic lesions, the cutoff value of HSI ratio of RILs was calculated.

Results

In all, 127 ischemic lesions were identified in 35 patients. HSI ratios of RILs were significantly lower than those of irreversible ischemic lesions (IILs) (p <0.0001). Based on a ROC curve analysis that compared the HSI ratio of all 127 lesions, the cutoff value of the HSI ratio of RILs was 1.4. After applying this cutoff value to the 127 ischemic lesions of the 35 patients, 20 patients (57%) were identified as having RILs with a HSI ratio of <1.4. In this 20 patients, the postoperative National Institutes of Health Stroke Scale (NIHSS) score at 24 hours was significantly lower (p = 0.007) and improvement in the NIHSS score was significantly higher (p = 0.018) than in the other patients.

Conclusion

A HSI ratio of <1.4 on preoperative DWI may reflect ischemic reversibility. In this study, the HSI ratio correlated with clinical findings associated with cerebral ischemia, and our method may be useful in assessing ischemic cores.

Trends in Endovascular Reperfusion Therapy for Acute Stroke after Introduction of Mechanical Thrombectomy Devices: Japanese Registry of NeuroEndovascular Therapy (JR-NET)3

In Japan, the era of thrombectomy for acute stroke started when the Merci retriever was approved in 2010 and the Penumbra system in 2011. New-generation Penumbra catheters (MAX series) and stent retrievers were introduced in 2013 and 2014, respectively. The aim of this study was to clarify the general status and trends in endovascular reperfusion therapy for stroke in Japan from 2010 to 2014. We extracted a total of 3705 patients (72.1 ± 12.2 years, 1482 women) from a nationwide study of patients receiving any neuroendovascular treatment, the Japanese Registry of NeuroEndovascular Therapy 3. Reperfusion therapy resulted in a successful reperfusion rate of 59%, and 31% of patients achieved a favorable outcome at 30 days of onset. The frequency of Merci-including procedures increased to 52% in the first half of 2011, but conversely decreased to 1% in the second half of 2014. The frequency of Penumbra-including procedures increased from 18% in the second half of 2011 to 67% in the first half of 2014, decreasing to 38% in the second half of 2014. The reperfusion rate and 30-day clinical outcomes remained almost unchanged until June 2013, and started to improve thereafter, coincident with the introduction and spread of newer-generation devices. The rate of successful reperfusion reached 71-76%, and 36-38% of patients achieved a favorable outcome in 2014. After multivariate adjustment for preprocedure variables, the calendar period from 2013 to 2014 was significantly associated with improvement in reperfusion rates and clinical outcomes.

Factors Associated with Unsuccessful Recanalization in Mechanical Thrombectomy for Acute Ischemic Stroke

Introduction

Mechanical thrombectomy (MT) for acute ischemic stroke has become a standard therapy, and the recanalization rate has significantly improved. However, some cases of unsuccessful recanalization still occur. We aimed to clarify patient factors associated with unsuccessful recanalization after MT for acute ischemic stroke.

Methods

This was a single-center, retrospective study of 119 consecutive patients with anterior circulation acute ischemic stroke who underwent MT at our hospital between April 2015 and March 2019. Successful recanalization after MT was defined as modified Treatment in Cerebral Ischemia (mTICI) grade 2b or 3, and unsuccessful recanalization was defined as mTICI grades 0–2a. Several factors were analyzed to assess their effect on recanalization rates.

Results

Successful recanalization was achieved in 88 patients (73.9%). The univariate analysis showed that female sex (38.6 vs. 67.7%, p = 0.007), a history of hypertension (53.4 vs. 83.9%, p = 0.003), and a longer time from groin puncture to recanalization (median 75 vs. 124 min, p < 0.001) were significantly associated with unsuccessful recanalization. The multivariate analysis confirmed that female sex (OR 3.18; 95% CI 1.12–9.02, p = 0.030), a history of hypertension (OR 4.84; 95% CI 1.32–17.8, p = 0.018), M2–3 occlusion (OR 4.26; 95% CI 1.36–13.3, p = 0.013), and the time from groin puncture to recanalization (per 10-min increase, OR 1.22; 95% CI 1.09–1.37, p < 0.001) were independently associated with unsuccessful recanalization.

Conclusion

Female sex and a history of hypertension might be predictors of unsuccessful recanalization after MT for anterior circulation acute ischemic stroke. Further studies are needed to fully evaluate predictors of recanalization.

Utility of Minimum Apparent Diffusion Coefficient Ratios in Alberta Stroke Program Early CT Score Regions for Deciding on Stroke Therapy

BACKGROUND AND PURPOSE

Therapeutic indications for recombinant tissue plasminogen activator therapy and endovascular therapy need to be assessed for patients with hyperacute ischemic stroke. We investigated the relationship between the minimum apparent diffusion coefficient ratios in each Alberta Stroke Program Early CT Score region and reversible lesion in patients with hyperacute ischemic stroke receiving recombinant tissue plasminogen activator therapy and/or treated with endovascular therapy.

MATERIALS AND METHODS

We retrospectively evaluated 29 patients with first ischemic stroke due to stenosis/occlusion of the internal carotid artery or horizontal portion of the middle cerebral artery that was successfully recanalized by recombinant tissue plasminogen activator therapy and/or treated with endovascular therapy. We measured the minimum apparent diffusion coefficient value in each Alberta Stroke Program Early CT Score region (11 regions) and calculated the ratio.

RESULTS

There was a significant difference in minimum apparent diffusion coefficient ratios between regions that included and did not include infarction (P < .0001), which were distinguishable with a cutoff value of .808 (area under the curve = .80, P < .001). A statistical difference in the proportion of infarction with the cutoff value was observed between patients treated with endovascular therapy and receiving recombinant tissue plasminogen activator therapy alone (9.9% versus 24.6%, P = .0041) and between patients with affected middle cerebral and internal carotid arteries (7.0% versus 24.2%, P = .0002). The lowest apparent diffusion coefficient ratio was associated with the time to recombinant tissue plasminogen activator injection.

CONCLUSIONS

Minimum apparent diffusion coefficient ratios in Alberta Stroke Program Early CT Score regions are useful in predicting therapeutic effect.

Hyperperfusion after Endovascular Reperfusion Therapy for Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Patients with acute ischemic stroke (AIS) may display prolonged neurological deficits and conscious disturbance even after successful endovascular thrombectomy. We hypothesized that hemodynamic change after reperfusion might influence outcomes. This study investigated the factors causing hyperperfusion and outcomes.

METHODS

We retrospectively analyzed 27 patients with AIS who underwent successful acute revascularization (TICI: Thrombolysis in Cerebral Infarction 2b + 3). Changes of the neurological status were precisely assessed by using the National Institutes of Health Stroke Scale (NIHSS). Ischemic lesions were scored by MRI with diffusion-weighted imaging (DWI), and blood flow in the middle cerebral artery territory was assessed by MRI with arterial spin labeling. Univariate analysis was performed to investigate correlations between hyperperfusion and demographic factors or the functional prognosis.

RESULTS

Thirteen of the 27 (48%) patients developed hyperperfusion after reperfusion. A significant correlation was seen between hyperperfusion and the improvement of NIHSS at 24 hours (P < .0001), the duration of disturbance of consciousness (days) (P < .0001), DWI-ASPECTS (P = .001), hemorrhagic transformation (P = .007), and mRS less than or equal to 2 at 90 days (P = .007).

CONCLUSIONS

The present findings suggested that some patients with AIS will develop hyperperfusion after successful acute revascularization. The status of hyperperfusion could prolong conscious disturbance and affect outcomes. Since the mechanism of hyperperfusion after revascularization depends on stroke etiology, diagnosing the type of ischemic stroke in the acute stage is important for managing postoperative treatment.

Assessment of veins in T2*-weighted MR angiography predicts infarct growth in hyperacute ischemic stroke

BACKGROUND AND PURPOSE

T2*-weighted magnetic resonance angiography (SWAN) detects hemodynamic insufficiency as hypointense areas in medullary or cortical veins. We therefore investigated whether SWAN can help predict ischemic penumbra-like lesions in patients with acute ischemic stroke (AIS).

MATERIALS AND METHODS

Magnetic resonance imaging (MRI) records-including SWAN, diffusion-weighted imaging (DWI), and magnetic resonance angiography (MRA)-of consecutive patients with major vessel occlusion within 6 h from AIS onset were analyzed. Acute recanalization was defined as an arterial occlusive lesion score of 2-3. A modified Alberta Stroke Program Early CT Score (mASPECTS) was used to evaluate ischemic areas revealed by SWAN and DWI. SWAN- and DWI-based mASPECTSs were calculated, and correlations between DWI-SWAN mismatches with final infarct lesions or clinical outcomes were evaluated.

RESULTS

Among the 35 patients included in this study, we confirmed cardioembolic stroke in 26, atherothrombotic stroke in 4, and unknown stroke etiology in 5. Overall, recanalization was achieved in 23 patients, who showed a higher follow-up DWI-based mASPECTS and lower modified Rankin Scale (mRS) score at 90 days than patients without recanalization. Initial SWAN- and follow-up DWI-based mASPECTSs were significantly higher for atherothrombotic stroke than for cardioembolic stroke. Of 12 patients without recanalization, DWI-SWAN mismatch was significantly correlated with infarct growth. Patients with recanalization showed no such correlation. In the assessment of clinical outcome, follow-up DWI-based mASPECTS and patient's age were significantly correlated with mRS at 90 days after stroke. A multivariate logistic regression analysis revealed that the follow-up DWI-based mASPECTS was independently associated with a favorable outcome 90 days after stroke.

CONCLUSIONS

For patients with AIS, DWI-SWAN mismatch might show penumbra-like lesions that would predict infarct growth without acute recanalization. Assessment of ischemic lesions from the venous side appears to be useful for considering the etiology and revascularization therapy.

[Stroke due to infective endocarditis diagnosed by the retrieved thrombus: a case report]

A 80-years-old woman suddenly presented with aphasia, right hemiparesis, and dysesthesia. MRA showed the left middle cerebral artery occlusion. She was diagnosed as hyperacute ischemic stroke. She was treated with intravenous recombinant tissue plasminogen activator and underwent endovascular thrombectomy. On admission, she had a fever and high C reactive protein, and was treated with antibiotic therapy. The pathological diagnosis of the retrieved thrombus revealed the cluster of the gram positive cocci. The blood culture was negative and thransthoracic echocardiogram did not detect the vegetation. She was finally diagnosed as cardioembolic stroke due to infective endocarditis based on the pathological diagnosis of the retrieved thrombus. The pathological diagnosis of the retrieved thrombus was quite important to clarify the cause of ischemic stroke.

Does Reducing the Duration from Symptom Onset to Recanalization Improve the Results of Intracranial Mechanical Thrombectomy in the Elderly?

Endovascular recanalization for acute major cerebral artery occlusion is effective within a short time after symptom onset. However, its efficacy in the elderly remains unknown. We assessed the efficacy of our comprehensive stroke center’s reduction of this time in 28 consecutive patients for elderly patients (defined as patients aged ≥75 years) with acute major cerebral artery occlusion treated with intravenous injection of tissue plasminogen activator, followed by thrombus retrieval by endovascular therapy. The patients were divided into groups according to whether they were treated before implementation of the time reduction measure (from January 2012 to May 2014) or after (from June 2014 to May 2015). The onset-to-door, onset-to-needle, onset-to-recanalization (O2R), door-to-image (D2I), door-to-needle (D2N), door-to-puncture (D2P), door-to-recanalization (D2R), and puncture-to-recanalization time intervals were compared between the two groups. There were 14 patients (including 8 elderly patients ≥80 years) before and 14 patients (including 10 elderly patients ≥80 years) after the time reduction measure. The mean duration of each of the following time intervals was significantly reduced after the time reduction measure (P < 0.05). To reduce the O2R time, the D2P time is the first time interval that can be reduced. At our center, conferences were regularly held to raise awareness among staff and make specific changes in the workflow, and overall time reduction was achieved. Similar results were obtained in elderly patients.

[Nephrotic syndrome might be an inhibitor of the endovascular recanalization in a patient with acute ischemic stroke]

A 65-year-old man with left hemiparesis was referred to our hospital by ambulance. Diffusion-weighted magnetic resonance imaging (DWI-MRI) showed a slight hyperintensity area in the right basal ganglion and deep white matter, and brain magnetic resonance angiography (MRA) revealed right middle cerebral artery (MCA) occlusion in the M1 proximal segment. Receiving intravenous rt-PA therapy, the patient showed no neurological improvement. Therefore emergency neuroendovascular revasculization was decided. After the first evacuation of the clot, the occlusion site was partly recanalyzed. However it was re-occluded after a few minutes. Then, mechanical disruption using balloon catheters were added for the occlusion site allowing it to be recanalyzed. After the acute ischemic stroke therapy, the patient was diagnosed as nephrotic syndrome, because his blood chemistry test indicated hypoproteinemia and urine examination showed proteinuria. Renal biopsy confirmed nephrotic syndrome due to AL amyloidosis. Nephrotic syndrome causes hypercoagulability and increases platelet aggregation. Thus we speculated that nephrotic syndrome inhibited the early recanalization in this patient.

Impact of the ASPECT scores and distribution on outcome among patients undergoing thrombectomy for acute ischemic stroke

INTRODUCTION

This study investigates whether the Alberta Stroke Program Early CT Score (ASPECTS) quantification is associated with outcome following mechanical thrombectomy.

OBJECTIVE

To determine whether preintervention non-perfect ASPECT scores involving cortical or subcortical regions and the side of the non-perfect ASPECT score affects outcomes.

METHODS

A retrospective review of a prospectively maintained database of patients with acute ischemic stroke involving the anterior circulation who underwent thrombectomy between May 2008 and August 2012 at a single tertiary care center. The device for mechanical thrombectomy used was the penumbra aspiration system (Penumbra Inc, Alameda, California, USA) and the Solitaire stent retriever (ev3, Irvine, California, USA). A 'blinded' neuroradiologist obtained ASPECTS quantification and noted each region demonstrating early changes.

RESULTS

149 patients (51.7% female, mean age 66.1±15.1 years) were included with an average National Institutes of Health Stroke Scale of 16.2±6.7. Patients with non-perfect ASPECT scores on pretreatment imaging were more likely to have a hemorrhagic conversion (p=0.04) evident on post-procedure CT. However, functional outcomes were the same. Patients with both cortical and basal ganglia non-perfect ASPECT scores were more likely to be in a persistent vegetative state or expire. No differences were identified in outcome among patients with left- versus right-sided infarcts affecting the basal ganglia or cortical regions.

CONCLUSIONS

These findings support a strategy of selecting candidacy for thrombectomy that does not exclude patients with non-perfect ASPECT scores involving either the basal ganglia or cortical regions. Outcomes were identical among patients with no non-perfect ASPECT scores and those with cortical or subcortical infarcts, despite a higher incidence of hemorrhagic conversion found among those with non-perfect ASPECT scores.

[A case of cerebral embolism caused by Cardiobacterium hominis endocarditis]

A 45-year-old woman was referred to our hospital by ambulance with left-sided palsy presented at dinner. Diffusion-weighted magnetic resonance imaging (DWI) showed a somewhat high intensity area in the right frontal lobe, and brain magnetic resonance angiography (MRA) revealed right middle cerebral artery (MCA) occlusion in the M1 distal segment. Although intravenous rt-PA treatment was initiated at 2 hours and 10 minutes after onset, recanalization was not achieved. The patient was diagnosed as infectious endocarditis, because highly echogenic vegetation was observed in the non-coronary cusp of the aortic valve; furthermore, Cardiobacterium hominis was incubated in blood culture, although fever was not so high and C-reactive protein (CRP) was not elevated at the time of hospitalization. It was thought that the bacteremia and infectious endocarditis had occurred due to tooth extraction about six months previously. The diagnosis of infectious endocarditis caused by the HACEK group containing C. hominis may become difficult because the fever was not so high and inflammation was not so severe.