PubTransformer

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Michael Knauth - Top 30 Publications

High Systolic Blood Pressure after Successful Endovascular Treatment Affects Early Functional Outcome in Acute Ischemic Stroke.

Endovascular treatment (EVT) has been shown to significantly improve functional outcome in patients with acute large cerebral vessel occlusions. To date, no evidence-based recommendations on blood pressure management after successful EVT exist. Previous studies showed an association between high pre-EVT systolic blood pressure (SBP) and functional outcome, but do not answer the question on how to manage blood pressure after successful recanalization. The purpose of this study was to determine the role of blood pressure measurements as a predictor for early functional outcome in patients with successful EVT.

One-Stop Management of Acute Stroke Patients: Minimizing Door-to-Reperfusion Times.

Intrahospital time delays significantly affect the neurological outcome of stroke patients with large-vessel occlusion. This study was conducted to determine whether a one-stop management can reduce intrahospital times of patients with acute large-vessel occlusion.

Comparing different thrombectomy techniques in five large-volume centers: a 'real world' observational study.

Thrombectomy has become the standard of care for acute ischaemic stroke due to large vessel occlusion. Aim of this study was to compare the radiological outcomes and time metrics of the various thrombectomy techniques.

Association between Embolic Stroke Patterns, ESUS Etiology, and New Diagnosis of Atrial Fibrillation: A Secondary Data Analysis of the Find-AF Trial.

Background. Atrial fibrillation (AF) is an important cause of embolic stroke of undetermined source (ESUS). Imaging-patterns like multiple infarcts, simultaneous involvement of different circulations, infarcts of different ages, and isolated cortical infarcts are likely to indicate cardioembolic stroke. The aim of our study was to evaluate the association between embolic stroke patterns, ESUS, and the new diagnosis of AF. Methods. Stroke etiology and imaging characteristics from patients included in the Find-AF study were obtained. Embolic stroke patterns in CT- or MR-imaging were correlated with the diagnosis of ESUS as well as the short- (on baseline ECG and during 7-day Holter) and long-term (12-month follow-up) diagnosis of AF. Results. From 281 patients included in the Find-AF study, 127 (45.2%) patients with ischemic lesions detected in CT or MRI were included. 26 (20.5%) of these patients had ESUS. At least one embolic stroke pattern was detected in 67 (52.7%) patients. Embolic stroke patterns were not associated with ESUS (OR 1.57, 0.65-3.79, p = 0.317), the short-term (OR 0.64, 0.26-1.58, p = 0.327) or long-term diagnosis of AF (OR 0.72, 0.31-1.68, p = 0.448). Conclusions. This secondary data analysis of the Find-AF study could not provide evidence for an association between embolic stroke patterns, ESUS, and the new diagnosis of AF.

Transcranial doppler sonography is not a valid diagnostic tool for detection of basilar artery stenosis or in-stent restenosis: a retrospective diagnostic study.

There are contradictory reports concerning the validity of transcranial sonography (TCD and TCCS) for examinations of the basilar artery. Here we investigated sensitivity and specificity of transcranial sonography for the detection of basilar artery stenosis and in-stent-restenosis compared to cerebral angiography.

Retriever first embolectomy (ReFirE): An alternative approach for challenging cervical access.

After endovascular treatment became the standard of care procedure for acute ischaemic stroke with large artery occlusion in 2015 the number of performed interventions has increased dramatically. Especially because age is no exclusion criterion for endovascular treatment, a relevant number of patients with difficult to access carotid arteries has to be treated. In these patients a direct puncture of the carotid is a valuable tool but is associated with severe complications and an initial learning curve. We therefore developed the so called retriever first embolectomy (ReFirE) technique in which a stentretriever is deployed over a 5F diagnostic catheter and a microcatheter to establish a stable anchor prior to accessing the internal carotid artery/intracranial vasculature with an 8F guide catheter and a 5F/6F intermediate catheter. We hereby report the first case in which we performed a thrombectomy applying our novel technique.

Computed tomography perfusion-based selection of endovascularly treated acute ischaemic stroke patients - Are there lessons to be learned from the pre-evidence era?

Introduction Some of the latest groundbreaking trials suggest that noncontrast cranial computed tomography and computed tomography-angiography are sufficient tools for patient selection within six hours of symptom onset. Before endovascular stroke therapy became the standard of care, patient selection was one of the most useful tools to avoid futile reperfusions. We report the outcomes of endovascularly treated stroke patients selected with a perfusion-based paradigm and discuss the implications in the current era of endovascular treatment. Material and methods After an interdisciplinary meeting in September 2012 we agreed to select thrombectomy candidates primarily based on computed tomography perfusion with a cerebral blood volume Alberta Stroke Program Early Computed Tomography Scale (CBV-ASPECTS) of <7 being a strong indicator of futile reperfusion. In this study, we retrospectively screened all patients with an M1 thrombosis in our neurointerventional database between September 2012 and December 2014. Results In 39 patients with a mean age of 69 years and a median admission National Institute of Health Stroke Scale of 17 the successful reperfusion rate was 74% and the favourable outcome rate at 90 days was 56%. Compared to previously published data from our database 2007-2011, we found that a two-point increase in median CBV-ASPECTS was associated with a significant increase in favourable outcomes. Conclusion Computed tomography perfusion imaging as an additional selection criterion significantly increased the rate of favourable clinical outcome in patients treated with mechanical thrombectomy. Although computed tomography perfusion has lost impact within the six-hour period, we still use it in cases beyond six hours as a means to broaden the therapeutic window.

Early computed tomography-based scores to predict decompressive hemicraniectomy after endovascular therapy in acute ischemic stroke.

Identification of patients requiring decompressive hemicraniectomy (DH) after endovascular therapy (EVT) is crucial as clinical signs are not reliable and early DH has been shown to improve clinical outcome. The aim of our study was to identify imaging-based scores to predict the risk for space occupying ischemic stroke and DH.

One Stop Management in Acute Stroke: First Mothership Patient Transported Directly to the Angiography Suite.

Maximizing First-Pass Complete Reperfusion with SAVE.

Endovascular techniques for treatment of large vessel occlusions (LVO) in patients with acute ischemic stroke (AIS) have advanced in recent years. We report a multicenter experience using a combined aspiration and stent retriever technique for mechanical thrombectomy (MT).

Retriever wire supported carotid artery revascularization (ReWiSed CARe) in acute ischemic stroke with underlying tandem occlusion caused by an internal carotid artery dissection: Technical note.

We hereby report a novel technical approach for the treatment of acute stroke with underlying tandem occlusion. The so-called retriever wire supported carotid artery revascularization (ReWiSed CARe) technique, utilizing the wire of a stent-retriever as a guiding wire for carotid artery stenting, is technically feasible in tandem occlusions caused by an internal carotid artery (ICA) dissection or high grade ICA stenosis. This technique eliminates the need to use a long microwire in order to maintain the position inside the true lumen of a dissection. Additionally, it leads to anterograde perfusion through the released stent-retriever during the time of ICA stenting, which is favorable in all tandem occlusion cases.

Effects of Workflow Optimization in Endovascularly Treated Stroke Patients - A Pre-Post Effectiveness Study.

Endovascular treatment of acute ischemic stroke has become standard of care for patients with large artery occlusion. Early restoration of blood flow is crucial for a good clinical outcome. We introduced an interdisciplinary standard operating procedure (SOP) between neuroradiologists, neurologists and anesthesiologists in order to streamline patient management. This study analyzes the effect of optimized workflow on periprocedural timings and its potential influence on clinical outcome. Data were extracted from a prospectively maintained university hospital stroke database. The standard operating procedure was established in February 2014. Of the 368 acute stroke patients undergoing endovascular treatment between 2008 and 2015, 278 patients were treated prior to and 90 after process optimization. Outcome measures were periprocedural time intervals and residual functional impairment. After implementation of the SOP, time from symptom onset to reperfusion was significantly reduced (median 264 min prior and 211 min after SOP-introduction (IQR 228-32 min and 161-278 min, respectively); P<0.001). Especially faster supply of imaging and prompt transfer of patients to the angiography suite contributed to this effect. Time between hospital admission and groin puncture was reduced by half after process optimization (median 64 min after versus 121 min prior to SOP-introduction (IQR 54-77 min and 96-161 min, respectively); P<0.001). Clinical outcome was significantly better after workflow optimization as measured with the modified Rankin Scale (common odds ratio (OR) 0.56; 95% CI 0.32-0.98; P = 0.038). Optimization of workflow and interdisciplinary teamwork significantly improved the outcome of patients with acute ischemic stroke due to a significant reduction of in-hospital examination, transportation, imaging and treatment times.

Bridging-therapy with intravenous recombinant tissue plasminogen activator improves functional outcome in patients with endovascular treatment in acute stroke.

Although endovascular treatment for proximal cerebral vessel occlusion is very effective, it remains controversial if intravenous thrombolysis (IVT) prior to endovascular treatment is superior compared to endovascular treatment alone. In this study we compared functional outcomes and recanalization rates of endovascularly treated stroke patients with and without bridging IVT.

Computed tomography-based quantification of lesion water uptake identifies patients within 4.5 hours of stroke onset: A multicenter observational study.

Many patients with stroke cannot receive intravenous thrombolysis because the time of symptom onset is unknown. We tested whether computed tomography (CT)-based quantification of water uptake in the ischemic tissue can identify patients with stroke onset within 4.5 hours, the time window of thrombolysis.

Latest generation of flat detector CT as a peri-interventional diagnostic tool: a comparative study with multidetector CT.

Flat detector CT (FDCT) has been used as a peri-interventional diagnostic tool in numerous studies with mixed results regarding image quality and detection of intracranial lesions. We compared the diagnostic aspects of the latest generation FDCT with standard multidetector CT (MDCT).

Early termination of THRILL, a prospective study of mechanical thrombectomy in patients with acute ischemic stroke ineligible for i.v. thrombolysis.

Transluminal angioplasty and stenting versus conservative treatment in patients with symptomatic basilar artery stenosis : Perspective for future clinical trials.

Two recent randomized controlled trials (RCT) consistently showed superiority of aggressive medical treatment versus percutaneous transluminal angioplasty and stenting (PTAS) in patients with intracranial artery stenosis. Patients with symptomatic basilar stenosis have a higher long-term risk of recurrent stroke compared to patients with anterior circulation stenosis but no study has specifically focused on the role of PTAS in this subgroup. The aim of our study was to investigate the subgroup of patients with symptomatic basilar artery stenosis to find evidence for the feasibility of a future clinical trial.

Aspiration Thrombectomy After Intravenous Alteplase Versus Intravenous Alteplase Alone.

Thrombectomy, primarily with stent retrievers with or without adjunctive aspiration, provided clinical benefit across multiple prospective randomized trials. Whether this benefit is exclusive to stent retrievers is unclear.

Added value of CT perfusion compared to CT angiography in predicting clinical outcomes of stroke patients treated with mechanical thrombectomy.

CTP images analyzed with the Alberta stroke program early CT scale (ASPECTS) have been shown to be optimal predictors of clinical outcome. In this study we compared two biomarkers, the cerebral blood volume (CBV)-ASPECTS and the CTA-ASPECTS as predictors of clinical outcome after thrombectomy.

Endovascular stroke therapy with the Aperio thrombectomy device.

The pharmaceutical therapy for acute ischemic stroke has shortcomings in reopening large vessels and dissolving long thrombi, and endovascular treatment has been found to provide added value. The Aperio thrombectomy device showed promising results in an experimental study. The purpose of this study was to evaluate the device clinically.

Multivariate dynamic prediction of ischemic infarction and tissue salvage as a function of time and degree of recanalization.

Benefit of endovascular recanalization beyond established treatment time windows likely exists in select stroke patients. However, there is currently no imaging model that predicts infarction adjusting for elapsed time between the pathologic snapshot of admission imaging until endovascular recanalization. We trained and cross validated a multivariate generalized linear model (GLM) that uses computer tomography perfusion and clinical data to quantify patient-specific dynamic change of tissue infarction depending on degree and time of recanalization. Multicenter data of 161 patients with proximal anterior circulation occlusion undergoing endovascular therapy were included. Multivariate voxelwise infarct probability was calculated within the GLM. The effect of increasing time to treatment and degree of recanalization on voxelwise infarction was calculated in each patient. Tissue benefit of successful relative to unsuccessful recanalization was shown up to 15 hours after onset in individual patients and decreased nonlinearly with time. On average, the relative reduction of infarct volume at the treatment interval of 5 hours was 53% and this salvage effect decreased by 5% units per hour to <5% after 10 additional hours to treatment. Treatment time-adjusted multivariate prediction of infarction by perfusion and clinical status may identify patients who benefit from extended time to recanalization therapy.

The Pattern of Brain Microhemorrhages After Severe Lung Failure Resembles the One Seen in High-Altitude Cerebral Edema.

After suffering from severe acute respiratory distress syndrome, several patients show generalized brain alterations and atrophy. A distinctive morphologic pattern of cerebral injury, however, has not been found so far.

Thrombectomy in patients ineligible for iv tPA (THRILL).

A relevant proportion of patients with acute ischemic stroke are ineligible for intravenous thrombolysis with recombinant tissue plasminogen activator. Mechanical thrombectomy offers a treatment alternative for these patients; however, only few data are available on its safety and efficacy.

Abnormalities in the normal appearing white matter of the cerebral hemisphere contralateral to a malignant brain tumor detected by diffusion tensor imaging.

Malignant brain tumors tend to migration and invasion of surrounding brain tissue. Histopathological studies reported malignant cells in macroscopically unsuspicious parenchyma (normal appearing white matter - NAWM) remote from the tumor localization. In early stages, diffuse interneural infiltration with changes of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) is hypothesized.

Hemosiderin deposition in the brain as footprint of high-altitude cerebral edema.

Based on recent findings of microhemorrhages (MHs) in the corpus callosum (CC) in 3 individuals after nonfatal high-altitude cerebral edema (HACE), we hypothesized that hemosiderin depositions in the brain after high-altitude exposure are specific for HACE and remain detectable over many years.

Time-resolved assessment of collateral flow using 4D CT angiography in large-vessel occlusion stroke.

In acute stroke patients with large vessel occlusion, collateral blood flow affects tissue fate and patient outcome. The visibility of collaterals on computed tomography angiography (CTA) strongly depends on the acquisition phase, but the optimal time point for collateral imaging is unknown.

Alberta Stroke Program Early CT Scale evaluation of multimodal computed tomography in predicting clinical outcomes of stroke patients treated with aspiration thrombectomy.

Patient selection is crucial in the endovascular treatment of acute ischemic stroke patients. Baseline computed tomographic (CT) images, evaluated with the Alberta Stroke Program Early CT Scale (ASPECTS), are considered significant predictors of outcome. In this study, we evaluated CT images and perfusion parameters, analyzed with ASPECTS, as final outcome predictors after endovascular stroke treatment.

Impact of a new metal artefact reduction algorithm in the noninvasive follow-up of intracranial clips, coils, and stents with flat-panel angiographic CTA: initial results.

Flat-panel angiographic CT after intravenous contrast agent application (ivACT) is increasingly used as a follow-up examination after coiling, clipping, or stenting. The purpose of this study was to evaluate the feasibility of a new metal artefact reduction algorithm (MARA) in patients treated for intracranial aneurysms and stenosis.

Feasibility of flat panel detector computed tomography for position assessment of external ventricular drainage.

New angiographic devices with flat panel detectors allow cross-sectional imaging within the angiographic suite. In patients receiving external ventricular drainage (EVD) to manage hydrocephalus following subarachnoid haemorrhage (SAH), these may help evaluating the position of an EVD without moving the patient to a conventional computed tomography (CT) scanner. It could facilitate patients' management in a life-threatening status. This study therefore compares conventional CT with post-interventional flat panel detector angiographic CT (FDCT) referring to the determinability of an accurate EVD position.

Evaluation of noninvasive follow-up methods for the detection of intracranial in-stent restenosis: a phantom study.

Intra-arterial digital subtraction angiography (IA-DSA), an invasive procedure, is the current reference examination after percutaneous transluminal angioplasty and stenting for the detection of in-stent restenosis (ISR). In this phantom study, we evaluated flat-panel angiographic computed tomography after intravenous contrast agent application (IV-ACT) and multidetector computed tomographic angiography (MDCTA) as potential noninvasive follow-up alternatives after intracranial percutaneous transluminal angioplasty and stenting.