Recanalization and reperfusion in acute ischemic stroke.

Revascularization remains the most intuitive strategy to reverse ischemic injury associated with arterial occlusion in acute stroke. Revascularization may lead to opening of an occluded artery, or recanalization, yet restoration of downstream flow, or reperfusion, may not ensue. Revascularization strategies and novel devices continue to broaden options for the treatment of acute stroke, but it is increasingly apparent that selection criteria to identify ideal cases are needed to refine triage and minimize adverse events. The results of recent work on reperfusion may rapidly alter routine clinical practice for evolving ischemia in the brain

Developing precision stroke imaging.

Stroke experts stand at the cusp of a unique opportunity to advance the care of patients with cerebrovascular disorders across the globe through improved imaging approaches. NIH initiatives including the Stroke Progress Review Group promotion of imaging in stroke research and the newly established NINDS Stroke Trials network converge with the rapidly evolving concept of precision medicine. Precision stroke imaging portends the coming shift to individualized approaches to cerebrovascular disorders where big data may be leveraged to identify and manage stroke risk with specific treatments utilizing an improved neuroimaging infrastructure, data collection, and analysis. We outline key aspects of the stroke imaging field where precision medicine may rapidly transform the care of stroke patients in the next few years

The future of ischemic stroke: flow from prehospital neuroprotection to definitive reperfusion.

Recent advances in ischemic stroke enable a seamless transition of the patient flow from the prehospital setting to definitive reperfusion, without the arbitrary separation of therapeutic phases of ischemia based on time alone. In 2013, the framework to understand and directly address the pathophysiology of cerebral blood flow that determines the timeline or evolution of ischemia in an individual case is given. This continuum of flow and the homeostasis of brain perfusion balanced by collaterals may be captured with serial imaging. Ongoing imaging core laboratory activities permit large-scale measurement of angiographic and tissue biomarkers of ischemia. Prehospital neuroprotection has become a reality and may be combined with revascularization therapies. Recent studies confirm that image-guided thrombolysis may be achieved without restrictive time windows. Baseline imaging patterns may be used to predict response to therapy and serial imaging may discern recanalization and reperfusion. Advanced techniques, such as arterial spin-labeled MRI, may also report hyperperfusion associated with hemorrhagic transformation. Endovascular therapies, including novel stent retriever devices, may augment revascularization and angiographic core laboratories may define optimal reperfusion. Serial evaluation of collaterals and reperfusion may identify definitive reperfusion linked with good clinical outcome rather than imposing arbitrary definitions of effective recanalization. Reperfusion injury and hemorrhagic transformation of various types may be detailed to explain clinical outcomes. Similar approaches may be used in intracranial atherosclerosis where flow, and not the degree of luminal stenosis, is paramount. Fractional flow may now be measured with computational fluid dynamics to identify high-risk lesions that require revascularization to restore the equilibrium of antegrade and collateral perfusion. Serial perfusion imaging of such cases may also illustrate inadequate cerebral blood volume gradients that may be more informative than blood flow delay alone. In sum, the growing understanding of collateral perfusion throughout all stages of ischemic stroke provides a framework for the future of ischemic stroke

Deep Learning for Period Classification of Historical Texts

In this study, we address the interesting task of classifying historical texts by their assumed period of writing. This task is useful in digital humanity studies where many texts have unidentified publication dates. For years, the typical approach for temporal text classification was supervised using machine-learning algorithms. These algorithms require careful feature engineering and considerable domain expertise to design a feature extractor to transform the raw text into a feature vector from which the classifier could learn to classify any unseen valid input. Recently, deep learning has produced extremely promising results for various tasks in natural language processing (NLP). The primary advantage of deep learning is that human engineers did not design the feature layers, but the features were extrapolated from data with a general-purpose learning procedure. We investigated deep learning models for period classification of historical texts. We compared three common models: paragraph vectors, convolutional neural networks (CNN), and recurrent neural networks (RNN). We demonstrate that the CNN and RNN models outperformed the paragraph vector model and supervised machine-learning algorithms. In addition, we constructed word embeddings for each time period and analyzed semantic changes of word meanings over time

Data science of stroke imaging and enlightenment of the penumbra.

Imaging protocols of acute ischemic stroke continue to hold significant uncertainties regarding patient selection for reperfusion therapy with thrombolysis and mechanical thrombectomy. Given that patient inclusion criteria can easily introduce biases that may be unaccounted for, the reproducibility and reliability of the patient screening method is of utmost importance in clinical trial design. The optimal imaging screening protocol for selection in targeted populations remains uncertain. Acute neuroimaging provides a snapshot in time of the brain parenchyma and vasculature. By identifying the at-risk but still viable penumbral tissue, imaging can help estimate the potential benefit of a reperfusion therapy in these patients. This paper provides a perspective about the assessment of the penumbral tissue in the context of acute stroke and reviews several neuroimaging models that have recently been developed to assess the penumbra in a more reliable fashion. The complexity and variability of imaging features and techniques used in stroke will ultimately require advanced data driven software tools to provide quantitative measures of risk/benefit of recanalization therapy and help aid in making the most favorable clinical decisions

Headache in a patient with Klinefelter's syndrome and hyperostosis frontalis interna.

Hyperostosis frontalis interna (HFI) has been reported in older women, but reports in men are rare. We present a novel case of migraine headache in a gentleman with Klinefelter's syndrome and HFI, along with a discussion of possible pathophysiologic mechanisms underlying both the headache and the HFI

To Tube or Not to Tube? The Role of Intubation during Stroke Thrombectomy.

In the 10 years since the FDA first cleared the use of endovascular devices for the treatment of acute stroke, definitive evidence that such therapy improves outcomes remains lacking. The decision to intubate patients undergoing stroke thrombectomy impacts multiple variables that may influence outcomes after stroke. Three main areas where intubation may deleteriously affect acute stroke management include the introduction of delays in revascularization, fluctuations in peri-procedural blood pressure, and hypocapnia, resulting in cerebral vasoconstriction. In this mini-review, we discuss the evidence supporting these limitations of intubation during stroke thrombectomy and encourage neurohospitalists, neurocritical care specialists, and neurointerventionalists to carefully consider the decision to intubate during thrombectomy and provide strategies to avoid potential complications associated with its use in acute stroke

"Sudden Drop" in Blood Pressure is Associated With Recanalization After Thrombolysis.

We aim to investigate whether the phenomenon of "sudden drop" in blood pressure (BP) within the first 2 hours is associated with vessel recanalization.We retrospectively examined clinical and imaging data from a consecutive series of patients with stroke with large vessel occlusion treated with intravenous thrombolysis (IVT). BP was monitored every 15 minutes during the first 2 hours, then every 30 minutes for 6 hours, and then every hour for 16 hours.We observed the phenomenon of "sudden drop" in systolic BP (≥20 mm Hg) in 82 (50.9%) patients in the first 2 hours and vessel recanalization in 87 (54.0%) patients 24 hours after treatment. This phenomenon was independently associated with recanalization (odds ratio 2.100; 95% confidence interval: 1.085-4.062; P = 0.028) after adjusting for the history of atrial fibrillation, coronary heart disease, and hypertension.The phenomenon of "sudden drop" in systolic BP with 20 mm Hg or greater between 2 continuous measurements within the first 2 hours is associated with recanalization after IVT in patients with large vessel occlusion, especially for middle cerebral artery occlusion