J. Scott Pannell

Vessel wall signal enhancement on 3-T MRI in acute stroke patients after stent retriever thrombectomy.

OBJECTIVE In vivo and in vitro studies have demonstrated histological evidence of iatrogenic endothelial injury after stent retriever thrombectomy. However, noncontrast vessel wall (VW)-MRI is insufficient to demonstrate vessel injury. Authors of this study prospectively evaluated iatrogenic endothelial damage after stent retriever thrombectomy in humans by utilizing high-resolution contrast-enhanced VW-MRI. Characterization of VW-MRI changes in vessels subject to mechanical injury from thrombectomy may allow better understanding of the biological effects of this intervention. METHODS The authors prospectively recruited 11 patients for this study. The treatment group included 6 postthrombectomy patients and the control group included 5 subjects undergoing MRI for nonvascular indications. All subjects were evaluated on a Signa HD× 3.0-T MRI scanner with an 8-channel head coil. Both pre- and postcontrast T1-weighted Cube VW images as well as MR angiograms were acquired. Sequences obtained for evaluation of the brain parenchyma included diffusion-weighted, gradient echo, and T2-FLAIR imaging. Two independent neuroradiologists, who were blinded to the treatment status of each patient, determined the presence of VW enhancement. Patient age, National Institutes of Health Stroke Scale score on presentation, location of occlusion, stroke etiology, type of device used, number of device deployments, Thrombolysis in Cerebral Infarction (TICI) reperfusion score, stroke volume, and 90-day modified Rankin Scale score were also noted. RESULTS Postcontrast T1-weighted VW enhancement was detected in the M2 segment in 100% of the thrombectomy patients, in the M1 segment in 83%, and in the internal carotid artery in 50%. One patient also demonstrated A1 segment enhancement, which was attributable to thrombectomy treatment of that vessel segment during the same procedure. None of the control patients demonstrated VW enhancement of their intracranial vasculature on T1-weighted images. CONCLUSIONS The study findings suggest that VW injury incurred during stent retriever thrombectomy can be reliably detected utilizing contrast-enhanced 3-T VW-MRI. The results further demonstrate that endothelial injury is associated with oversizing of stent retrievers relative to the treated vessel. Further studies are needed to evaluate the clinical significance of endothelial injury and to characterize the differential effects of various devices.

Interventional Management of Acute Ischemic Stroke: A Systematic Review

Opinion statementHistorically, acute ischemic stroke (AIS) trials defined syndromes according to acute clinical presentation and post-ictus parenchymal imaging. With improvements in real-time arterial imaging, modern AIS treatment demands a structural approach based upon the level of cerebrovascular occlusion. The poor concordance of presenting National Institute of Health Stroke Scale (NIHSS) with vessel occlusion in recent trials bespeaks the need for an anatomic perspective. Specifically, patients with large-vessel occlusion (LVO) represent a distinct entity with a poorer prognosis than general AIS patients. Ongoing clinical trials and therapeutic strategies must recognize the varied natural history of AIS patients. Endovascular therapy offers promise in patients with the most severe strokes.

Simulator-Based Angiography and Endovascular Neurosurgery Curriculum: A Longitudinal Evaluation of Performance Following Simulator-Based Angiography Training

This study establishes performance metrics for angiography and neuroendovascular surgery procedures based on longitudinal improvement in individual trainees with differing levels of training and experience. Over the course of 30 days, five trainees performed 10 diagnostic angiograms, coiled 10 carotid terminus aneurysms in the setting of subarachnoid hemorrhage, and performed 10 left middle cerebral artery embolectomies on a Simbionix Angio Mentor™ simulator. All procedures were nonconsecutive. Total procedure time, fluoroscopy time, contrast dose, heart rate, blood pressures, medications administered, packing densities, the number of coils used, and the number of stent-retriever passes were recorded. Image quality was rated, and the absolute value of technically unsafe events was recorded. The trainees’ device selection, macrovascular access, microvascular access, clinical management, and the overall performance of the trainee was rated during each procedure based on a traditional Likert scale score of 1=fail, 2=poor, 3=satisfactory, 4=good, and 5=excellent. These ordinal values correspond with published assessment scales on surgical technique. After performing five diagnostic angiograms and five embolectomies, all participants demonstrated marked decreases in procedure time, fluoroscopy doses, contrast doses, and adverse technical events; marked improvements in image quality, device selection, access scores, and overall technical performance were additionally observed (p < 0.05). Similarly, trainees demonstrated marked improvement in technical performance and clinical management after five coiling procedures (p < 0.05). However, trainees with less prior experience deploying coils continued to experience intra-procedural ruptures up to the eighth embolization procedure; this observation likely corresponded with less tactile procedural experience to an exertion of greater force than appropriate for coil placement. Trainees across all levels of training and prior experience demonstrated a significant performance improvement after completion of our simulator curriculum consisting of five diagnostic angiograms, five embolectomy cases, and 10 aneurysm coil embolizations.

Low-profile Visualized Intraluminal Support Junior Device for the Treatment of Intracranial Aneurysms.

Objective: Early case series suggest that the recently introduced Low-profile Visualized Intraluminal Support Junior (LVIS Jr.) device (MicroVention-Terumo, Inc., Tustin, CA) may be used to treat wide-necked aneurysms that would otherwise require treatment with intrasaccular devices or open surgery. We report our single-center experience utilizing LVIS Jr. to treat intracranial aneurysms involving 1.8-2.5 mm parent arteries. Methods: We retrospectively reviewed records of patients treated with the LVIS Jr. device for intracranial aneurysms at a single center. A total of 21 aneurysms were treated in 18 patients. Aneurysms were 2-25 mm in diameter; one was ruptured, while three had recurred after previous rupture and treatment. Lesions were distributed across the anterior (n=12) and posterior (n=9) circulations. Three were fusiform morphology. Results: Stent deployment was successful in 100% of cases with no immediate complications. Seventeen aneurysms were treated with stent-assisted coil embolization resulting in immediate complete occlusion in 94% of cases. Two fusiform aneurysms arising from the posterior circulation were further treated with elective clip ligation after delayed expansion and recurrence; no lesions required further endovascular treatment. Four aneurysms were treated by flow diversion with stand-alone LVIS Jr. stent, and complete occlusion was achieved in three cases. Small foci of delayed ischemic injury were noted in two patients in the setting of antiplatelet medication noncompliance. No in-stent stenosis, migration, hemorrhage, or permanent deficits were observed. Good functional outcome based on the modified Rankin Scale score (mRS ≤ 2) was achieved in 100% of cases. Conclusion: Our midterm results suggest that the LVIS Jr. stent may be used for a variety of intracranial aneurysms involving small parent arteries (1.8-2.5 mm) with complete angiographic occlusion, parent vessel preservation, and functional clinical outcomes. This off-label expansion would increase the number of aneurysms amenable to endovascular treatment. Future studies may build upon our experiences with flow diversion and treatment of complex or multiple lesions.

Ventricular Tract Hemorrhage Following Intracranial Nail Removal: Utility of Real-time Endovascular Assistance

Penetrating brain trauma commonly results in occult neurovascular injury. Detailed cerebrovascular imaging can evaluate the relationship of intracranial foreign bodies to major vascular structures, assess for traumatic pseudoaneurysms, and ensure hemostasis during surgical removal. We report a case of a self-inflicted intracranial nail gun injury causing a communicating ventricular tract hemorrhage upon removal, as well as a delayed pseudoaneurysm. Pre- and post-operative vascular imaging, as well as intra-operative endovascular assistance, was critical to successful foreign body removal in this patient. This report demonstrates the utility of endovascular techniques for the assessment and treatment of occult cerebrovascular injuries from intracranial foreign bodies.

Sphenoid wing dysplasia and plexiform neurofibroma in neurofibromatosis type 1

A 13-year-old female with neurofibromatosis type 1 (NF1) presented with a large left-sided facial plexiform neurofibroma, with significant disruption of her facial anatomy. Other than loss of vision in the left eye, she was neurologically intact. Computed tomography (Fig. 1a) and post-contrast T1 weighted magnetic resonance imaging (Fig. 1b) demonstrated extensive left-sided sphenoid wing dysplasia associated with the tumor, with a loss of bony integrity around the petrous carotid. She underwent permanent liquid endovascular embolization of two superficial temporal artery pedicles, with no meaningful residual, prior to surgical tumor resection. Significant distortion of the left middle cerebral artery (MCA) candelabra and elongation of the petrocavernous internal carotid artery (ICA) was seen during angiography (Fig. 1c), due to traction from sphenoid wing dysplasia. These findings were critical for surgical planning of a frontal craniotomy and orbitozygomatic osteotomy (Fig. 2), as resection of this facial tumor without recognition of the bony loss/remodeling could lead to easy iatrogenic violation of the intracranial space, cerebrovascular injury, and/or disruption of the patients fetal variant internal carotid artery vascular supply (not shown), in an otherwise extracranial tumor. The patient tolerated all procedures without change in neurologic status. Sphenoid wing dysplasia occurs in 5–10% of NF1 cases, is often unilateral with a contiguous plexiform neurofibroma (PNF), and can be progressive. Surgical resection is the preferred treatment of complex facial PNFs, yet injury to nearby cranial nerves and external carotid branches are common sources of morbidity. As demonstrated by this case, pre-operative cerebral vascular imaging identifying anatomical distortions from bony dysplasia is critical to the prevention of iatrogenic CNS insults during surgical resection.

Advances in minimally invasive treatment of hemorrhagic and ischemic stroke.

Cerebrovascular diseases, including ischemic and hemorrhagic strokes, affect more than 6 million US adults annually. Strokes cause high rates of morbidity and mortality due to the central nervous systems sensitivity to disruptions in blood flow, and are refractory to traditional surgical interventions. A variety of minimally invasive surgical and endovascular approaches have recently been developed to improve patient outcomes following stroke. Hemorrhagic strokes, also referred to as intracranial hemorrhages (ICH), have clinical outcomes largely dependent on hemorrhage location, size, and secondary peri-hematomal edema (Rennert et al., 2015). In theory, clot evacuation addresses local mass effect and enhances survival of edematous penumbral tissue (Rennert et al., 2015), however, multiple clinical trials have failed to show a definitive benefit for surgical hematoma evacuation following ICH (Rennert et al., 2015). The largest of these is the 2005 International Surgical Trial in Intracerebral Haemorrhage (STICH) trial (Mendelow et al., 2005), wherein 1,033 patients with spontaneous lobar and/or basal ganglia ICH were randomly selected for surgical evacuation within 24 hours of presentation, or initial conservative treatment. In this study there was no significant difference in favorable outcomes across groups (26% vs. 24%, P = 0.4), yet subgroup analysis revealed that patients with superficial hematomas (≤ 1 cm from the cortical surface) may benefit from surgery, supporting the hypothesis that decreasing secondary neurologic injury from manipulation of injured penumbral tissue during clot removal critically affects outcomes. Current guidelines thus recommend consideration of open surgical evacuation only in specific clinical scenarios, such as lobar clots > 30 mL and within 1 cm of the cortical surface. In this setting, there has been a recent push to develop minimally invasive approaches for ICH removal. One such minimally invasive approach is stereotactic surgery (i.e., using an imaging based three dimensional roadmap for surgical localization) combined with intra-clot injection of thrombolytic agents, such as tissue plasminogen activator (tPA). The Minimally Invasive (Stereotactic) Surgery plus rTPA for ICH Evaluation (MISTIE) randomized clinical trials have demonstrated the safety and effectiveness of this approach for reducing clot and perihematomal edema (Rennert et al., 2015), with a larger phase III clinical efficacy trial currently ongoing. Stereotactic endoscopic evacuation of intraventricular hemorrhages (IVH) in ICH is also being explored, as is targeted infusion of intraventricular thrombolytics based on pre-clinical and clinical safety data (Gaberel et al., 2014; Rennert et al., 2015). Endoscopic techniques (i.e., burr hole craniotomy with direct hematoma visualization/removal through a sheath) are similarly appealing due to minimization of secondary neurologic injury from surgical manipulation. Direct hematoma visualization with this approach also allows for identification and real-time treatment of the original bleeding source, and is associated with improved evacuation rates compared to stereotactic aspiration (Cho et al., 2006). Moreover, this technique may be particularly well suited for deeper hemorrhages, with preliminary data showing improved clot evacuation rates and post-operative neurologic status compared to open surgery in patients with hemorrhage in deeper brain structures such as the putamen and thalamus (Nagasaka et al., 2011). New technology combining real-time neuronavigation with neuroendoscopy has also been developed and trialed for ICH evacuation (Rennert et al., 2015). The initial multi-center clinical experience with one such system was recently reported, with twenty-nine patients with lobar, basal ganglia, and brainstem hemorrhages (including six with the poor prognostic finding of intraventricular extension) treated with a nearly 92% technical success rate and low morbidity and mortality (Spiotta et al., 2015). While general clinical guidelines for endoscopic ICH evacuation are currently supratentorial hemorrhages ≥ 30 mL, with a goal of <15 mL post-operative residual, combined neuronavigation/neuroendoscopy has already been integrated into the senior authors clinical practice (Figure 1), and has the potential to expand these indications and gain widespread adaptation for the treatment of ICH as additional clinical data is obtained. Figure 1 Endoscopic hematoma evacuation. Minimally invasive surgical techniques are also being increasingly utilized in ischemic strokes, where the rapid restoration of normal blood flow via thrombolytics or mechanical thrombectomy is critical. In fact, for large vessel occlusive strokes, multiple large, randomized trials were recently stopped for dramatic outcome improvement with thrombectomy for acute large vessel stroke (Berkhemer et al., 2015; Campbell et al., 2015; Goyal et al., 2015), making this intervention the new standard of care (Powers et al., 2015). The initial data with mechanical thrombectomy nonetheless demonstrated a decoupling of clinical outcomes with the technical success of angiographic reperfusion (Teng et al., 2015). These findings, combined with the known detrimental effects of disruptions in physiologic blood flow on endothelial cell maintenance, remodeling, and cytokine signaling, support the hypothesis that vascular endothelial cell damage resulting from altered flow dynamics, reperfusion injury, and/or iatrogenic trauma may potentiate secondary neuronal injury in post-thrombectomy stroke patients (Figure 2) (Teng et al., 2015). Figure 2 Schematic illustration of the hypothesis that thrombectomy-associated iatrogenic endothelial cell injury can influence stroke outcomes. To better assess the effect of thrombectomy devices on the endothelium, we recently developed a novel in vitro live cell platform capable of characterizing endothelial injury patterns and mechanisms across thrombectomy devices (Figure 3) (Teng et al., 2015). This technology allowed for the tubular growth of endothelial cells under peristaltic flow, with post-thrombectomy injuries easily visualized and quantified with a novel rotational-scanning image system and three-dimensional reconstruction. Specifically, six thrombectomy devices were tested across three vessel diameters in vitro: (1) 5MAX ACE (Penumbra, Inc., Alameda, CA) with A Direct Aspiration first Pass Technique (ADAPT), (2) MERCI (3.0 firm) (Concentric Medical Inc/Stryker Corp., Kalamazoo, MI), (3) 5MAX with Separator (Penumbra, Inc.), (4) 5MAX with Separator 3D (Penumbra, Inc.), (5) Solitaire FR (4 × 20 mm) (Covidien, Ltd, Mansfield, OH) and (6) TREVO (Stryker Corp.). Characteristic injuries were seen across devices, ranging from a nearly complete degloving injury with the Merci retriever, to a focused circumferential or linear denudation with the 5MAX ACE with the ADAPT technique and the Separator 3D. These findings were surprising by ours (Teng et al., 2015) and others (Gory et al., 2013) data from in vivo experiments, and validate the in vitro live cell model as an important tool for thrombectomy device assessment and future design evaluations. Figure 3 In vitro live cell model demonstrating the heterogeneous effects of thrombectomy devices on the endothelium. As research in other surgical fields has demonstrated multiple advantages of minimally invasive techniques, including avoidance of large incisions requiring less sedation, less trauma to the patient, and potentially lower treatment costs resulting from shorter hospital courses and a reduced need for post-operative intensive medical care, it is not surprising that minimally invasive surgical approaches to stroke have recently gained traction. As highlighted herein, the successful development and integration of such technology requires a strong pre-clinical foundation and well designed clinical trials. The promising results in the aforementioned and ongoing clinical trials suggest the future utilization of minimally invasive techniques for the treatment of hemorrhagic and ischemic stroke will continue to increase. RCR, JSP and AAK contributed to idea generation, paper preparation, and revisions. The authors are grateful to Victor W. Wong for his original figure artwork. AAK has previously received competitive grants from Covidien Ltd. and Penumbra Inc, and holds consulting arrangements for physician training with Stryker Neurovascular, Covidien Ltd., and Penumbra Inc. AAK has no direct financial interests related to this work. RCR and JSP have no disclosures concerning the materials or methods used in this study or the findings specified in this paper.

Hypoplastic Internal Carotid Artery Co-Presenting with Neurofibromatosis and Intracranial Masses.

Neurofibromatosis type 1 (NF1) is associated with systemic vascular disease, and it can also affect intracranial vasculature in a small percentage of patients. Very rarely, NF1 may co-present with hypoplasia of the internal carotid artery (ICA). Prior reports have documented NF1 with bilateral optic gliomas and a unilateral hypoplastic internal carotid artery; however, we report a case with the aforementioned findings in addition to a right-sided lentiform mass. This case report further suggests a common congenital pathway related to neurofibromin loss of function resulting in both nerve sheath tumors and cerebrovascular anomalies.

Management of Through-and-Through Penetrating Skull Injury: A Railroad Spike That Transgressed the Anterior Skull Base

BACKGROUND Penetrating injuries involving foreign objects that transgress the entirety of the human skull present challenges in the management of vascular injuries, infectious risk, cerebrospinal fluid leak, and cosmetic repair. Ultimately, effective management of these injuries requires a multidisciplinary team and judicious surgical planning. CASE DESCRIPTION Here we present the treatment of a patient who experienced a penetrating injury from a railroad spike, with entry and exit points involving the left and right anterior aspects of the temporal fossa, respectively. CONCLUSIONS The rationale for management decisions is reviewed in the context of the published literature.

Impact of preoperative endovascular embolization on immediate meningioma resection outcomes

OBJECTIVE Preoperative embolization of meningiomas can facilitate their resection when they are difficult to remove. The optimal use and timing of such a procedure remains controversial given the risk of embolization-linked morbidity in select clinical settings. In this work, the authors used a large national database to study the impact of immediate preoperative embolization on the immediate outcomes of meningioma resection. METHODS Meningioma patients who had undergone elective resection were identified in the National (Nationwide) Inpatient Sample (NIS) for the period 2002-2014. Patients who had undergone preoperative embolization were propensity score matched to those who had not, adjusting for patient and hospital characteristics. Associations between preoperative embolization and morbidity, mortality, and nonroutine discharge were investigated. RESULTS Overall, 27,008 admissions met the inclusion criteria, and 633 patients (2.34%) had undergone preoperative embolization and 26,375 (97.66%) had not. The embolization group was younger (55.17 vs 57.69 years, p < 0.001) with a lower proportion of females (63.5% vs 69.1%, p = 0.003), higher Charlson Comorbidity Index (p = 0.002), and higher disease severity (p < 0.001). Propensity score matching retained 413 embolization and 413 nonembolization patients. In the matched cohort, preoperative embolization was associated with increased rates of cerebral edema (25.2% vs 17.7%, p = 0.009), posthemorrhagic anemia or transfusion (21.8% vs 13.8%, p = 0.003), and nonroutine discharge (42.8% vs 35.7%, p = 0.039). There was no difference in mortality (≤ 2.4% vs ≤ 2.4%, p = 0.82). Among the embolization patients, the mean interval from embolization to resection was 1.49 days. On multivariate analysis, a longer interval was significantly associated with nonroutine discharge (OR 1.33, p = 0.004) but not with complications or mortality. CONCLUSIONS Relative to meningioma patients who do not undergo preoperative embolization in the same admission, those who do have higher rates of cerebral edema and nonroutine discharge but not higher rates of stroke or death. Thus, meningiomas requiring preoperative embolization represent a distinct clinical entity that requires prolonged, more complex care. Further, among embolization patients, the timing of resection did not affect the risk of in-hospital complications, suggesting that the timing of surgery can be determined according to surgeon discretion.