Victor Xiao Dong Yang

Minimally invasive endovascular embolization is used to treat a wide range of diseases in neurology, oncology, and trauma where the vascular morphologies and corresponding hemodynamics vary greatly. Current techniques based on metallic coils, flow diverters, liquid embolics, and suspended microspheres are limited in their ability to address a wide variety of vasculature and can be plagued by complications including distal migration, compaction, and inappropriate vascular remodeling. Further, these endovascular devices currently offer limited therapeutic functions beyond flow control such as drug delivery. Herein, a novel in situ microcatheter‐based photomodulated extrusion approach capable of dynamically tuning the physical and morphological properties of injectable hydrogels, optimizing for local hemodynamic environment and vascular morphology, is proposed and demonstrated. A shear thinning and photoactivated poly(ethylene glycol diacrylate)‐nanosilicate (PEGDA‐nSi) hydrogel is used to demonstrate multiple extrusion modes which are controlled by photokinetics and device configurations. Real‐time photomodulation of injected hydrogel viscosity and modulus is successfully used for embolization in various vasculatures, including high‐flow large vessels and arterial‐to‐arterial capillary shunts. Furthermore, a generalizable therapeutic delivery platform is proposed by demonstrating a core–shell structured extrusion encapsulating doxorubicin to achieve a more sustained release compared to unencapsulated payload.

Background: The endovascular treatment of cerebral aneurysms has become widespread but may still be limited by recurrence rates or complications. The discovery of novel embolic strategies may help mitigate these concerns. Methods: We formulated a Photosensitive Hydrogel Polymer (PHP) embolic agent which is low-viscosity, shear-thinning, and radio-opaque. After the filling of an aneurysm with PHP with balloon assistance, we utilized photopolymerization to induce solidification. Different methods of light delivery for photopolymerization were assessed in silicone models of aneurysms and in four acute animal trials with venous anastomosis aneurysms in pigs. Then, balloon-assisted embolization with PHP and photopolymerization was performed in three aneurysms in pigs with a one-month follow-up. Filling volume, recurrence rates, and complications were recorded. Results: The PHP was found to be suitable for the intravascular delivery and treatment of cerebral aneurysms. It was found that light delivery through the balloon catheter, as opposed to light delivery through the injection microcatheter, led to higher rates of filling in the 3D model and acute animal model for cerebral aneurysms. Using the balloon-assisted embolization and light delivery strategy, three wide-necked aneurysms were treated without complication. One-month follow-up showed no recurrence or neck remnants. Conclusions: We demonstrated a novel method of balloon-assisted photosensitive hydrogel polymer embolization and photopolymerization, leading to complete aneurysm filling with no recurrence at 1 month in three wide-necked aneurysms in pigs. This promising methodology will be investigated further with longer-term comparative animal trials.

SPIE Digital Library Proceedings

Machine-vision image guided C4-C5 unilateral cervical pedicle screw insertion: case report and review of literature Tiffany Yeretsian, Carolyn Lai, Daipayan Guha, Joel Ramjist, Victor X. D. Yang

OBJECTIVE: Mechanical endovascular thrombectomy (EVT) is an increasingly relied-on treatment for clot retrieval in the context of ischemic strokes, which otherwise are associated with significant morbidity and mortality. Despite several known risks associated with this procedure, there is a high degree of technical heterogeneity across both centers and operators. The most common procedural complications occur at the point of transfemoral access (the common femoral artery), and include access-site hematomas, dissections, and pseudoaneurysms. Other interventional fields have previously popularized the use of ultrasound to enhance the anatomical localization of structures relevant to vascular access and thereby reducing access-site complications. In this study, the authors aimed to describe the ultrasound-guided EVT technique performed at a large, quaternary neurovascular referral center, and to characterize the effects of ultrasound guidance on access-site complications. METHODS: A retrospective chart review of all patients treated with EVT at a single center between January 2013 and August 2020 was performed. Patients in this cohort were treated using a universal, unique, ultrasound-guided, single-wall puncture technique, which bears several theoretical advantages over the standard technique of arterial puncture via palpation. RESULTS: There were 479 patients treated with EVT within the study period. Twenty patients in the cohort were identified as having experienced some form of access-site complication. Eight (1.67%) of these patients experienced minor access-site complications, all of which were groin hematomas and none of which were clinically significant, as defined by requiring surgical or interventional management or transfusion. The remaining 12 patients experienced arterial dissection (n = 5), arterial pseudoaneurysm (n = 4), retroperitoneal hematoma (n = 2), or arterial occlusion (n = 1), with only 1.04% (5/479) requiring surgical or interventional management or transfusion. CONCLUSIONS: The authors found an overall reduction in total access-site complications as well as minor access-site complications in the study cohort compared with previously published randomized controlled trials and observational studies in the recent literature. The findings suggested that there may be a role for routine use of ultrasound-guided puncture techniques in EVT to decrease rates of complications.

Approximately 40% of cancer patients will develop spinal metastases (1), which can present with axial pain, vertebral compression fracture (VCF), and radiculopathy, with 5 to 10% having extra osseous extension in the form of epidural disease. The latter is critical, given that progression to metastatic epidural spinal cord compression (MESCC) can lead to a significant impairment in quality of life resulting from severe pain and devastating neurologic deficits (2). Moreover, patients may require surgical intervention (3), which has its own consequences with respect to morbidity, mortality, and delays in subsequent oncologic care.

Diagnostic imaging of the spinal canal has evolved considerably over the past two decades.¹ Non-invasive imaging modalities are the radiological tools of choice for the majority of spinal pathologies including: trauma, tumors, infections, and inflammatory disease.² In spinal trauma, computed tomography (CT) is very sensitive in the detection of fractures or dislocations, and magnetic resonance (MR) imaging can reliably identify cord compression, transections, edema, and hemorrhages.³ Although significant progress has been made at assessing structural changes related to trauma and evaluating residual function, non-invasive spinal cord imaging modalities continue to be hindered by susceptibility differences, motion secondary to cardiac function, and the small cross-sectional area of the spinal cord leading to limited clinical utility.^{4 – 7}

Background: Blunt cerebrovascular injuries (BCVIs) may occur following trauma and lead to ischemic stroke if untreated. Antithrombotic therapy decreases this risk, however, the optimal agent has yet to be determined in this population. Aim of this study was to compare the risk-benefit profile of antiplatelet (AP) versus anticoagulant (AC) therapy in rates of ischemic stroke and hemorrhagic complications in BCVI patients. Methods: We performed a retrospective review of BCVI patients at our tertiary care Trauma hospital from 2010-2015, and a systematic review and meta-analysis of the literature. The OVID Medline, Embase, Web of Science, and Cochrane Library databases were searched from inception to September 16, 2019. References of included publications were searched manually for other relevant papers. The search was limited to articles in humans, in patients >= 18 years of age, and English. Studies that reported treatment-stratified clinical outcomes following AP or AC treatment in BCVI patients were included. Exclusion criteria included case reports, case series with nType of study Review Article Level of evidence II

BACKGROUND: Research on the presence of sex-based differences in the outcomes of patients undergoing endovascular thrombectomy for acute ischemic stroke has reached differing conclusions. PURPOSE: This review aimed to determine whether sex influences the outcome of patients with large-vessel occlusion stroke undergoing endovascular thrombectomy. STUDY SELECTION: We performed a systematic review and meta-analysis of endovascular thrombectomy studies with either stratified cohort outcomes according to sex (females versus males) or effect size reported for the consequence of sex versus outcomes. We included 33 articles with 7335 patients. DATA ANALYSIS: We pooled ORs for the 90-day mRS score, 90-day mortality, symptomatic intracranial hemorrhage, and recanalization. DATA SYNTHESIS: Pooled 90-day good outcomes (mRS ≤ 2) were better for men than women (OR = 1.29; 95% CI, 1.09–1.53; P = <.001, I² = 56.95%). The odds of the other outcomes, recanalization (OR = 0.94; 95% CI, 0.77–1.15; P = .38, I² = 0%), 90-day mortality (OR = 1.11; 95% CI, 0.89–1.38; P = .093, I² = 0%), and symptomatic intracranial hemorrhage (OR = 1.40; 95% CI, 0.99–1.99; P = .069, I² = 0%) were comparable between men and women. LIMITATIONS: Moderate heterogeneity was found. Most studies included were retrospective in nature. In addition, the randomized trials included were not specifically designed to compare outcomes between sexes. CONCLUSIONS: Women undergoing endovascular thrombectomy for large-vessel occlusion have inferior 90-day clinical outcomes. Sex-specific outcomes should be investigated further in future trials as well as pathophysiologic studies.