Felix C. NgAustin Health · Department of Neurology
Felix C. Ng
MBBS/BMedSc, DCH, MPH
About
59
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Introduction
Skills and Expertise
Publications
Publications (59)
Background
Mobile stroke units have been shown to deliver faster patient care and improve clinical outcomes. However, costs associated with staffing limit their use to densely populated cities. Using the Melbourne mobile stroke unit, we aim to evaluate the safety, timeliness, and resource efficiency of a telemedicine model, where the neurologist as...
The no‐reflow phenomenon is a potential contributor to poor outcome despite successful thrombectomy. There are multiple proposed imaging‐based definitions of no‐reflow leading to wide variations in reported prevalence. We investigated the agreement between existing imaging definitions and compared the characteristics and outcomes of patients identi...
Purpose
For nearly half of patients who undergo Endovascular Thrombectomy following ischemic stroke, successful recanalisation does not guarantee a good outcome. Understanding the underlying tissue changes in the infarct tissue with the help of biomarkers specific to ischemic stroke could offer valuable insights for better treatment and patient man...
Background and Objectives
We recently developed a model (PROCEED) that predicts the occurrence of persistent perfusion deficit (PPD) at 24 hours in patients with incomplete angiographic reperfusion after thrombectomy. This study aims to externally validate the PROCEED model using prospectively acquired multicenter data.
Methods
Individual patient...
Background: Endovascular thrombectomy (EVT) improves long-term outcome in patients presenting with large ischemic core but is associated with early neurological worsening (ENW), potentially related to cerebral edema post-reperfusion. We investigated whether EVT increases edema development, and the relationship between edema and ENW in a secondary a...
Introduction: The no-reflow phenomenon (persistent microvascular hypoperfusion despite macrovascular angiographic reperfusion) represents an explanation to poor outcome despite successful thrombectomy. There remains no universally-accepted definition to standardise future studies. We aim to compare the clinical features and outcomes of patients ide...
Introduction: Endovascular thrombectomy (EVT) reduces disability in patients with large ischemic core stroke. Increasing core volume is prognostic but does not modify treatment effect. CT hypodensity can vary within an area of core. We assessed the relationship between the severity of CT core hypodensity and clinical outcome in the SELECT2 trial.
M...
Cerebral oedema following acute ischemic infarction has been correlated with poor functional outcomes and is the driving mechanism of malignant infarction. Measurements of midline shift and qualitative assessment for herniation are currently the main CT indicators for cerebral oedema but have limited sensitivity for small cortical infarcts and are...
Introduction
The benefit of additional reperfusion attempts in patients with partial angiographic reperfusion (TICI2b) is unknown. The PROCEED model predicts subsequent favorable occurrence of complete reperfusion (i.e. delayed reperfusion [DR]) at 24 hours after initial incomplete angiographic reperfusion at the conclusion of thrombectomy. This st...
Background
Following reperfusion treatment in ischemic stroke, CT imaging at 24-hours is widely used to assess radiological outcomes. Even without visible hyperattenuation, occult angiographic contrast may persist in the brain and confound Hounsfield Unit-based imaging metrics such as Net Water Uptake (NWU).AimsWe aimed to assess the presence and f...
Background
The no-reflow phenomenon refers to the absence of microvascular reperfusion despite macrovascular reperfusion.AimThe aim of this analysis was to summarize the available clinical evidence on no-reflow in patients with acute ischemic stroke.MethodsA systematic literature review and a meta-analysis of clinical data on definition, rates and...
Background
The clinical course of patients with incomplete reperfusion after thrombectomy, defined as an expanded Thrombolysis in Cerebral Infarction (eTICI) score of 2a–2c, is heterogeneous. Patients showing delayed reperfusion (DR) have good clinical outcomes, almost comparable to patients with ad-hoc TICI3 reperfusion. We aimed to develop and in...
Introduction: Magnetic susceptibility is a radiological contrast mechanism that may provide a measure of oxygenation and contribute to an understanding the pathophysiology of stroke. Currently, there are few studies that have explored magnetic susceptibility in ischemic tissue as a marker of tissue injury. Our study assesses day one ischemic tissue...
Introduction: CT performed 24h post-treatment is widely used to assess radiological outcomes in stroke studies. Even without visible hyperattenuation, occult angiographic contrast may persist in the brain and confound Hounsfield Unit-based imaging metrics such as Net Water Uptake (NWU), a measure of cerebral edema based on tissue hypoattenuation. W...
Introduction:
Reperfusion therapy is highly beneficial for ischemic stroke. Reduction in both infarct growth and edema are plausible mediators of clinical benefit with reperfusion. We aimed to quantify these mediators and their interrelationship.
Methods:
In a pooled, patient-level analysis of EXTEND-IA trials and SELECT study, we employed a med...
Background
The benefit of combined treatment with intravenous thrombolysis before endovascular thrombectomy in patients with acute ischaemic stroke caused by large vessel occlusion remains unclear. We hypothesised that the clinical outcomes of patients with stroke with large vessel occlusion treated with direct endovascular thrombectomy within 4·5...
Background
Mobile stroke units (MSUs) equipped with a CT scanner reduce time to thrombolytic treatment and improve patient outcomes. We tested the hypothesis that tenecteplase administered in an MSU would result in superior reperfusion at hospital arrival, when compared with alteplase.
Methods
The TASTE-A trial is a phase 2, randomised, open-label...
Introduction:
Mobile stroke units (MSUs) equipped with a CT scanner are increasingly being used to assess and treat stroke patients' prehospital with thrombolysis and transfer them to the most appropriate hospital for ongoing stroke care and thrombectomy when indicated. The effect of MSUs in both reducing the time to reperfusion treatment and impr...
Background:
Cerebral edema after large hemispheric infarction is associated with poor functional outcome and mortality. Net water uptake (NWU) quantifies the degree of hypoattenuation on unenhanced-computed tomography (CT) and is increasingly used to measure cerebral edema in stroke research. Hemorrhagic transformation and parenchymal contrast sta...
Background
Emerging data suggest tissue within the infarct lesion is not homogenously damaged following ischemic stroke but has a gradient of injury. Using blood-brain-barrier (BBB) disruption as a marker of tissue injury, we tested whether therapeutic reperfusion improves clinical outcome by reducing the severity of tissue injury within the infarc...
Background and Objectives
Detailed study of tenecteplase (TNK) in patients greater than 80 years of age is limited. The objective of our study was to assess the safety and efficacy of TNK at 0.25 and 0.40 mg/kg doses in patients greater than 80 years with large vessel occlusion.
Methods
A pooled analysis of the EXTEND-IA TNK randomized controlled...
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...
Background and Purpose
The National Institutes of Health Stroke Scale (NIHSS) underestimates clinical severity in posterior circulation stroke and patients presenting with low NIHSS may be considered ineligible for reperfusion therapies. This study aimed to develop a modified version of the NIHSS, the Posterior NIHSS (POST-NIHSS), to improve NIHSS...
Background
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-radiological features of this phenomenon, and its associations with outcomes in three international randomized con...
Importance
Some patients have poor outcomes despite small infarcts after endovascular therapy (EVT), while others with large infarcts do well. Understanding why these discrepancies occur may help to optimize EVT outcomes.
Objective
To validate exploratory findings from the Endovascular Treatment for Small Core and Anterior Circulation Proximal Occ...
Background and Purpose
Whether reperfusion into infarcted tissue exacerbates cerebral edema has treatment implications in patients presenting with extensive irreversible injury. We investigated the effects of endovascular thrombectomy and reperfusion on cerebral edema in patients presenting with radiological evidence of large hemispheric infarction...
The relationship between reperfusion and edema is unclear, with experimental and clinical data yielding conflicting results. We investigated whether the extent of salvageable and irreversibly-injured tissue at baseline influenced the effect of therapeutic reperfusion on cerebral edema. In a pooled analysis of 415 patients with anterior circulation...
Background: Blood Brain Barrier (BBB) disruption is central to vasogenic edema development after ischemia in preclinical studies. We investigated the relationship between BBB disruption and cerebral edema in patients receiving reperfusion therapies for anterior circulation large vessel occlusion.
Methods: In a post-hoc pooled analysis of the Tenect...
Objective
To investigate the efficacy of tenecteplase (TNK), a genetically modified variant of alteplase with greater fibrin specificity and longer half-life than alteplase, prior to endovascular thrombectomy (EVT) in patients with basilar artery occlusion (BAO).
Methods
To determine whether tenecteplase is associated with better reperfusion rates...
Background and Purpose
Severity-based assessment tools may assist in prehospital triage of patients to comprehensive stroke centers (CSCs) for endovascular thrombectomy (EVT), but criticisms regarding diagnostic inaccuracy have not been adequately addressed. This study aimed to quantify the benefits and disadvantages of severity-based triage in a l...
Background
Patients who have had a stroke with unknown time of onset have been previously excluded from thrombolysis. We aimed to establish whether intravenous alteplase is safe and effective in such patients when salvageable tissue has been identified with imaging biomarkers.
Methods
We did a systematic review and meta-analysis of individual pati...
Importance
Intravenous thrombolysis with tenecteplase improves reperfusion prior to endovascular thrombectomy for ischemic stroke compared with alteplase.
Objective
To determine whether 0.40 mg/kg of tenecteplase safely improves reperfusion before endovascular thrombectomy vs 0.25 mg/kg of tenecteplase in patients with large vessel occlusion ische...
Aim:
To evaluate the degree of variability in microstructural injury within and adjacent to regions identified as infarcted tissue using diffusion tensor imaging (DTI).
Methods:
In this prospective longitudinal study, 18 patients presenting within 12 h of anterior circulation acute ischemic stroke who underwent CT perfusion (CTP) at baseline fol...
Background: Tenecteplase (TNK) is a genetically modified variant of alteplase with greater fibrin specificity and longer half-life than alteplase. The recent Tenecteplase versus Alteplase before Endovascular Therapy for Ischemic Stroke (EXTEND-IA TNK) trial demonstrated that increased reperfusion with TNK compared to alteplase prior to endovascular...
Objective: To evaluate the degree of variability in microstructural injury within and adjacent to regions identified as infarcted tissue using Diffusion Tensor Imaging (DTI).
Methods: Perfusion CT was performed in 18 patients within 12 hours of ischemic stroke onset followed by Fluid-attenuated Inversion recovery (FLAIR) and DTI one month after str...
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 adv...
Background and Purpose—
The benefit of endovascular therapy in extended time windows has been demonstrated in patients with anterior circulation large vessel occlusion ischemic stroke and favorable imaging profile. We evaluated whether collaterals and thrombus burden influence the associations between revascularization, time-to-treatment, and outco...
BACKGROUND:
Stroke thrombolysis with alteplase is currently recommended 0-4·5 h after stroke onset. We aimed to determine whether perfusion imaging can identify patients with salvageable brain tissue with symptoms 4·5 h or more from stroke onset or with symptoms on waking who might benefit from thrombolysis.
METHODS:
In this systematic review...
Background: The Melbourne Mobile Stroke Unit (MSU) utilises a specialised ambulance with on-board CT scanner and multidisciplinary team to provide on-scene imaging, treatment and triage for central Melbourne, Australia. We describe the operational impact of the MSU on stroke onset to treatment time for acute reperfusion therapy.
Methods: Data from...
Introduction: Even when accounting for lesion topography, radiological Final Infarct Volume (FIV) after acute ischemic stroke (AIS) correlates only moderately with clinical outcome. Pathology in normal-appearing “salvaged” peri-infarct tissue and partial preservation within radiologically infarcted tissue may contribute to the variance between FIV...
Background and Purpose—
Impaired microvascular reperfusion despite complete recanalization (no-reflow) represents a potential therapeutic target to improve outcomes after recanalization therapies. Although well documented in animal models, this phenomenon has not been demonstrated clinically. We investigated whether transcranial Doppler can detect...
Background:
Administration of intravenous idarucizumab to reverse dabigatran anticoagulation prior to thrombolysis for patients with acute ischemic stroke has been previously described, but not in the prehospital setting. The speed and predictability of idarucizumab reversal is well suited to prehospital treatment in a mobile stroke unit and allow...
Background and purpose:
Interhospital transfer is a critical component in the treatment of acute anterior circulation large vessel occlusive stroke transferred for mechanical thrombectomy. Real-world data for benchmarking and theoretical modeling are limited. We sought to characterize transfer workflow from primary stroke center (PSC) to comprehen...
We read with interest the recent study of Grossberg et al1 on cervical carotid pseudo-occlusion (PO) showing that PO is relatively common in patients with isolated intracranial internal carotid artery occlusion. We are writing to further highlight the clinical relevance of this poorly recognized entity and the need for an alternative noninvasive di...
Background:
Differentiation between true acute tandem occlusion involving the extracranial internal carotid artery (ICA) from pseudotandem occlusion with a patent extracranial ICA has important prognostic and therapeutic implications. We explored the utility of perfusion-derived 4-dimensional CT angiogram (4D-CTA) in identifying carotid pseudo-occ...
Background and purpose:
The use of thrombolysis in acute minor ischemic stroke (MIS) remains controversial. We sought to determine the safety and efficacy of intravenous tissue-type plasminogen activator (IV-tPA) in acute MIS patients with demonstrable penumbra on computed tomographic perfusion study.
Methods:
Consecutive MIS patients with Natio...
Correct identification of symptomatic high-grade internal carotid artery stenosis from low-grade or total chronic occlusion is critical for patient selection for urgent carotid endarterectomy. Carotid pseudo-occlusion is a flow-related artifact on noninvasive imaging that can lead to an incorrect diagnosis of total internal carotid artery occlusion...
Behçet disease (BD) is a rare relapsing, multisystem vasculitis characterised by recurrent oral and genital ulcers, and uveitis. As an autoimmune small vessel vasculitis, BD can involve other organs including the skin, joints, nervous system, kidney and the gastrointestinal tract. This report describes a 40-year-old woman who presented with an unco...
Novices can be quickly and easily taught to ultrasonographically measure optic nerve sheath diameter as a non-invasive surrogate for intracranial pressure. One intensive care unit senior medical officer, one junior intensive care unit registrar, one junior neurosurgery trainee and two registered nurses, all ultrasound novices, were given a four-hou...
Novices can be quickly and easily taught to ultrasonographically measure optic nerve sheath diameter as a noninvasive surrogate for intracranial pressure. One intensive care unit senior medical officer, one junior intensive care unit registrar, one junior neurosurgery trainee and two registered nurses, all ultrasound novices, were given a four-hour...