Immediate procedural safety of adjunctive proximal coil occlusion in middle meningeal artery embolization for chronic subdural hematomas: Experience in 137 cases.

BACKGROUND: Endovascular embolization of the middle meningeal artery (MMA) has emerged as an adjunctive and stand-alone modality for the management of chronic subdural hematomas (cSDH). We report our experience utilizing proximal MMA coil embolization to augment cSDH devascularization in MMA embolization. METHODS: MMA embolization cases with adjunctive proximal MMA coiling were retrospectively identified from a prospectively maintained IRB-approved database of the senior authors. RESULTS: Of the 137 cases, all patients (n = 89, 100%) were symptomatic and underwent an MMA embolization procedure for cSDH. 50 of the patients underwent bilateral embolizations, with 53% (n = 72) for left-sided and 47% (n = 65) for right-sided cSDH. The anterior MMA branch was embolized in 19 (14%), posterior in 16 (12%), and both in 102 (74.5%) cases. Penetration of the liquid embolic to the contralateral MMA or into the falx was present in 38 (28%) and 31 (23%) cases, respectively, and 46 (34%) cases had ophthalmic or petrous collateral (n = 41, 30%) branches. MMA branches coiled include the primary trunk (25.5%, n = 35), primary and anterior or posterior MMA trunks (20%, n = 28), or primary with the anterior and posterior trunks (54%, n = 74). A mild ipsilateral facial nerve palsy was reported, which remained stable at discharge and follow-up. Absence of anterograde flow in the MMA occurred in 137 (100%) cases, and no cases required periprocedural rescue surgery for cSDH evacuation. The average follow-up length was 170 ± 17.9 days, cSDH was reduced by 4.24 ± 0.5(mm) and the midline shift by 1.46 ± 0.27(mm). Complete resolution was achieved in 63 (46.0%) cases. CONCLUSION: Proximal MMA coil embolization is a safe technique for providing additional embolization/occlusion of the MMA in cSDH embolization procedures. Further studies are needed to evaluate the potential added efficacy of this technique.

Recurrence Rates Following Treatment of Spinal Vascular Malformations: A Systematic Review and Meta-Analysis.

BACKGROUND: Spinal vascular malformations (SVMs), including arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs), are a varied group of vascular lesions that can be subclassified according to localization, vascular structure, and hemodynamics. Early intervention is necessary to halt progression of disease and minimize irreversible dysfunction. We sought to characterize initial treatment success and recurrence rates following interventional treatment of various types of SVMs. METHODS: A systematic review and meta-analysis were performed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. SVMs were categorized into 4 groups: dural AVFs, perimedullary AVFs, intramedullary AVMs, and extradural-intradural AVMs (e.g., epidural, paraspinal). Initial occlusion, recurrence, and complication rates were compared using random-effects analysis. RESULTS: There were 112 manuscripts included, with a total of 5626 patients with SVM. For treatment, 2735 patients underwent endovascular embolization, 2854 underwent surgical resection, and 37 underwent stereotactic radiosurgery. The initial treatment success and overall recurrence rates following surgical resection of all SVMs were 89.5% (95% CI: 80.5%-98.5%) and 2.3% (95% CI: 0.9%-3.7%), respectively. Those rates following endovascular embolization were 55.9% (95% CI: 30.3%-81.5%) and 27.7% (95% CI: 11.2%-44.2%), respectively. Higher rates of initial treatment success and lower rates of recurrence with surgery were observed in all subtypes compared to embolization. Overall complication rates were higher after embolization for each of the SVM categories. CONCLUSIONS: Surgical resection of SVMs provided higher rates of initial complete occlusion and lower rates of recurrence than endovascular techniques. Attaining technical success through obliteration must still be weighed against clinical impact and natural history of the specific vascular malformation.

Minimally invasive pericranial flap harvest through a supraorbital eyebrow craniotomy: Technical note in salvage skull base reconstruction.

BACKGROUND AND IMPORTANCE: The supraorbital eyebrow craniotomy is a minimally invasive approach that provides access to pathologies of the anterior and middle cranial fossae. Vascularized flaps are preferred when considering reconstructive options, however, small incisions may not provide adequate access to vascularized tissue. We present two cases demonstrating a modified technique for harvesting pericranium through an eyebrow supraorbital craniotomy for reconstruction of large skull base defects. CLINICAL PRESENTATION: The first case is of a 62-year-old woman with an invasive esthesioneuroblastoma. Multiple resections and reconstructions, including a large frontal craniectomy and titanium mesh cranioplasty, resulted in refractory tension pneumocephalus. A supraorbital craniotomy was performed with endoscope-assisted harvesting of a pericranial flap through a coronal plane stab incision for definitive repair. The second case is a 44-year-old woman with a high-grade neuroendocrine tumor transgressing the anterior cranial fossa. Resection was achieved via combined supraorbital eyebrow craniotomy and endoscopic endonasal approach. A multilayered reconstruction including a pericranial flap from above and a nasoseptal flap from below was used to reconstruct the defect. The pericranial flap was again harvested with endoscope assistance through a coronal plane stab incision. Both cases had excellent outcomes with no post-operative cerebrospinal fluid leak. CONCLUSION: Repair of large anterior cranial fossa defects with a vascularized pericranial flap can be performed through a supraorbital eyebrow craniotomy. Utilizing small, strategically placed transverse (coronal plane) incisions behind the hairline allows for the endoscope-assisted harvesting of a highly customized flap. This modified technique increases the flexibility of the minimally invasive supraorbital craniotomy.

Supraorbital and mini-pterional keyhole craniotomies for brain tumors: a clinical and anatomical comparison of indications and outcomes in 204 cases.

OBJECTIVE: The authors' objective was to compare the indications, outcomes, and anatomical limits of supraorbital (SO) and mini-pterional (MP) craniotomies in patients with intra- and extraaxial brain tumors, and to assess approach selection, utility of endoscopy, and surgical field overlap. METHODS: A retrospective analysis was conducted of all brain tumor patients who underwent an SO or MP approach. The analyzed characteristics included pathology, endoscopy use, extent of resection, length of stay (LOS), and complications. On the basis of preoperative MRI data, tumor heatmaps were constructed to compare surgical access provided by both routes, including coronal projection heatmaps for parasellar tumors. RESULTS: From 2007 to 2020, 158 patients underwent 173 (84.8%) SO craniotomies and 30 patients underwent 31 (15.2%) MP craniotomies; 71 (34.8%) procedures were reoperations. Of these 204 operations, 110 (63.6%) SO and 21 (67.7%) MP approaches were for extraaxial tumors (meningiomas in 65% and 76.2%, respectively). Gliomas and metastases together represented 84.1% and 70% of intraaxial tumors accessed with SO and MP approaches, respectively. Overall, 56.1% of tumors accessed with the SO approach and 41.9% of those accessed with the MP approach were in the parasellar region. Axial projection heatmaps showed that SO access extended along the entire ipsilateral and medial contralateral anterior cranial fossa, parasellar region, ipsilateral sylvian fissure, medial middle cranial fossa, and anterior midbrain, whereas MP access was limited to the ipsilateral middle cranial fossa, sylvian fissure, lateral parasellar region, and posterior aspect of anterior cranial fossa. Coronal projection heatmaps showed that parasellar access extended further superiorly with the SO approach compared with that of the MP approach. Endoscopy was utilized in 98 (56.6%) SO craniotomies and 7 (22.6%) MP craniotomies, with further tumor resection in 48 (49%) and 5 (71.4%) cases, respectively. Endoscope-assisted tumor removal was clustered in areas that were generally at farther distances from the craniotomy or in angled locations such as the cribriform plate region where microscopic visualization is limited. Gross-total or near-total resection was achieved in 120/173 (69%) SO approaches and 21/31 (68%) MP approaches. Major complications occurred in 11 (6.4%) SO approaches and 1 (3.2%) MP approach (p = 0.49). The median LOS decreased to 2 days in the last 2 years of the study. CONCLUSIONS: This clinical experience suggests the SO and MP craniotomies are versatile, safe, and complementary approaches for tumors located in the anterior and middle cranial fossae and perisylvian and parasellar regions. The SO route, used in 85% of cases, achieved greater overall reach than the MP route. Both approaches may benefit from expanded visualization with endoscopy.

Streamlining brain tumor surgery care during the COVID-19 pandemic: A case-control study.

BACKGROUND: The COVID-19 pandemic forced a reconsideration of surgical patient management in the setting of scarce resources and risk of viral transmission. Herein we assess the impact of implementing a protocol of more rigorous patient education, recovery room assessment for non-ICU admission, earlier mobilization and post-discharge communication for patients undergoing brain tumor surgery. METHODS: A case-control retrospective review was undertaken at a community hospital with a dedicated neurosurgery and otolaryngology team using minimally invasive surgical techniques, total intravenous anesthesia (TIVA) and early post-operative imaging protocols. All patients undergoing craniotomy or endoscopic endonasal removal of a brain, skull base or pituitary tumor were included during two non-overlapping periods: March 2019-January 2020 (pre-pandemic epoch) versus March 2020-January 2021 (pandemic epoch with streamlined care protocol implemented). Data collection included demographics, preoperative American Society of Anesthesiologists (ASA) status, tumor pathology, and tumor resection and remission rates. Primary outcomes were ICU utilization and hospital length of stay (LOS). Secondary outcomes were complications, readmissions and reoperations. FINDINGS: Of 295 patients, 163 patients were treated pre-pandemic (58% women, mean age 53.2±16 years) and 132 were treated during the pandemic (52% women, mean age 52.3±17 years). From pre-pandemic to pandemic, ICU utilization decreased from 92(54%) to 43(29%) of operations (p<0.001) and hospital LOS≤1 day increased from 21(12.2%) to 60(41.4%), p<0.001, respectively. For craniotomy cohort, median LOS was 2 days for both epochs; median ICU LOS decreased from 1 to 0 days (p<0.001), ICU use decreased from 73(80%) to 29(33%),(p<0.001). For endonasal cohort, median LOS decreased from 2 to 1 days; median ICU LOS was 0 days for both epochs; (p<0.001). There were no differences pre-pandemic versus pandemic in ASA scores, resection/remission rates, readmissions or reoperations. CONCLUSION: This experience suggests the COVID-19 pandemic provided an opportunity for implementing a brain tumor care protocol to facilitate safely decreasing ICU utilization and accelerating discharge home without an increase in complications, readmission or reoperations. More rigorous patient education, recovery room assessment for non-ICU admission, earlier mobilization and post-discharge communication, layered upon a foundation of minimally invasive surgery, TIVA anesthesia and early post-operative imaging are possible contributors to these favorable trends.

Creating Clinically Relevant Aneurysm Sizes in the Rabbit Surgical Elastase Model.

BACKGROUND: Creating aneurysm sizes in animal models that resemble human aneurysms is essential to study and test neuroendovascular devices. The commonly used rabbit surgical elastase model, however, produces saccular aneurysms that are smaller than those typically treated in humans. The goal of this study was to determine whether an increased vessel stump length and the addition of calcium chloride to the incubation solution has an effect on the resulting aneurysm size. METHODS: Using a modified aneurysm creation method, 32 female New Zealand White rabbits underwent aneurysm creation procedures. Subjects were equally allocated into 4 different groups based on vessel stump length (2 cm controls vs. 3 cm) and incubation solution (elastase alone controls vs. a 1:1 mixture of elastase and calcium chloride). At 4 weeks, all animals underwent angiography to determine the resulting aneurysm size by a neurointerventionalist who was blinded to treatment group. RESULTS: An increase in stump length from 2 cm to 3 cm resulted in a significant increase in the height of aneurysm (P < 0.05). Compared with control animals, the combination of a 3-cm stump length and the addition of calcium chloride to the incubation solution resulted in a significant increase in aneurysm height, width, and volume (P < 0.05). CONCLUSIONS: Creating larger aneurysms is necessary for the rabbit model to be more clinically relevant. Our study demonstrated that the utilization of a 3-cm vessel stump as well as both calcium chloride and elastase in the incubation solution results in aneurysm sizes that more closely resemble the population of aneurysms treated in humans.

Comparison of Transradial vs Transfemoral Access in Neurovascular Fellowship Training: Overcoming the Learning Curve.

BACKGROUND: The transradial access (TRA) is rapidly gaining popularity for neuroendovascular procedures as there is strong evidence for its benefits compared to the traditional transfemoral access (TFA). However, the transition to TRA bears some challenges including optimization of the interventional suite set-up and workflow as well as its impact on fellowship training. OBJECTIVE: To compare the learning curves of TFA and TRA for diagnostic cerebral angiograms in neuroendovascular fellowship training. METHODS: We prospectively collected diagnostic angiogram procedural data on the performance of 2 neuroendovascular fellows with no prior endovascular experience who trained at our institution from July 2018 until June 2019. Metrics for operator proficiency were minutes of fluoroscopy time, procedure time, and volume of contrast used. RESULTS: A total of 293 diagnostic angiograms were included in the analysis. Of those, 57.7% were TRA and 42.3% were TFA. The median contrast dose was 60 cc, and the median radiation dose was 14 000 µGy. The overall complication rate was 1.4% consisting of 2 groin hematomas, 1 wrist hematoma, and 1 access-site infection using TFA. The crossover rate to TFA was 2.1%. Proficiency was achieved after 60 femoral and 95 radial cases based on fluoroscopy time, 52 femoral and 77 radial cases based on procedure time, and 53 femoral and 64 radial cases based on contrast volume. CONCLUSION: Our study demonstrates that the use of TRA can be safely incorporated into neuroendovascular training without causing an increase in complications or significantly prolonging procedure time or contrast use.

Feasibility and initial experience of left radial approach for diagnostic neuroangiography.

Neuroangiography has seen a recent shift from transfemoral to transradial access. In transradial neuroangiography, the right dominant hand is the main access used. However, the left side may be used specifically for left posterior circulation pathologies and when right access cannot be used. This study describes our initial experience with left radial access for diagnostic neuroangiography and assesses the feasibility and safety of this technique. We performed a retrospective review of a prospective database of consecutive patients between April 2018 and January 2020, and identified 20 patients whom a left radial access was used for neurovascular procedures. Left transradial neuroangiography was successful in all 20 patients and provided the sought diagnostic information; no patient required conversion to right radial or femoral access. Pathology consisted of anterior circulation aneurysms in 17 patients (85%), brain tumor in 1 patient (5%), and intracranial atherosclerosis disease involving the middle cerebral artery in 2 patients (10%). The left radial artery was accessed at the anatomic snuffbox in 18 patients (90%) and the wrist in 2 patients (10%). A single vessel was accessed in 7 (35%), two vessels in 8 (40%), three vessels in 4 (20%), and four vessels in 1 (5%). Catheterization was successful in 71% of the cases for the right internal carotid artery and in only 7.7% for the left internal carotid artery. There were no instances of radial artery spasm, radial artery occlusion, or procedural complications. Our initial experience found the left transradial access to be a potentially feasible approach for diagnostic neuroangiography even beyond the left vertebral artery. The approach is strongly favored by patients but has significant limitations compared with the right-sided approach.

Endovascular Management of Complex Fenestration-Associated Aneurysms: A Single-Institution Retrospective Study and Review of Existing Techniques.

BACKGROUND: Aneurysms associated with fenestrations of intracranial arteries are exceptionally rare findings. Management strategies for these aneurysms are not well-defined, especially regarding endovascular treatment. We sought to investigate the strategies and feasibility of endovascular treatment approaches for various fenestration-associated intracranial aneurysms. METHODS: We performed a retrospective chart review of 2000 aneurysms treated endovascularly, identifying 8 aneurysms located at arterial fenestrations. The technical details and procedural outcomes were reviewed to identify common management approaches, technical nuances, and treatment outcomes. RESULTS: There were 3 (37.5%) aneurysms associated with fenestrations of the basilar artery or vertebrobasilar junction. All 3 were successfully treated with a previously undescribed coil-assisted flow-diversion technique, resulting in complete obliteration. Three (37.5%) aneurysms were associated with fenestrations of the anterior communicating artery. Of those, 2 were successfully treated with stent-assisted coil embolization and 1 with coil embolization alone. One (12.5%) aneurysm was associated with a fenestration of the paraclinoid internal carotid artery and 1 (12.5%) aneurysm found was at the takeoff of the posterior inferior cerebellar artery at a fenestration of the vertebral artery. Both were successfully treated with coil-assisted flow diversion. There were no permanent procedural complications. Major considerations for endovascular management of these aneurysms were the dominance of fenestration trunks, aneurysms arising from the fenestration apex or a fenestration limb, amenability to flow diversion, and anticipation of vascular remodeling. CONCLUSIONS: Fenestration-associated aneurysms are very rare. We have identified common factors to help guide decision-making for endovascular approaches and demonstrate successful aneurysm treatment using these methods.

A comparison of radial versus femoral artery access for acute stroke interventions.

OBJECTIVE: In this study, the authors aimed to investigate procedural and clinical outcomes between radial and femoral artery access in patients undergoing thrombectomy for acute stroke. METHODS: The authors conducted a single-institution retrospective analysis of 104 patients who underwent mechanical thrombectomy, 52 via transradial access and 52 via traditional transfemoral access. They analyzed various procedural and clinical metrics between the two patient cohorts. RESULTS: There was no difference between patient demographics or presenting symptoms of stroke severity between patients treated via transradial or transfemoral access. The mean procedural time was similar between the two treatment cohorts: 60.35 ± 36.81 minutes for the transradial group versus 65.50 ± 29.92 minutes for the transfemoral group (p = 0.451). The mean total fluoroscopy time for the procedure was similar between the two patient cohorts (20.31 ± 11.68 for radial vs 18.49 ± 11.78 minutes for femoral, p = 0.898). The majority of patients underwent thrombolysis in cerebral infarction score 2b/3 revascularization, regardless of access site (92.3% for radial vs 94.2% for femoral, p = 0.696). There was no significant difference in the incidence of access site or periprocedural complications between the transradial and transfemoral cohorts. CONCLUSIONS: Acute stroke intervention performed via transradial access is feasible and effective, with no significant difference in procedural and clinical outcomes compared with traditional transfemoral access. Larger studies are required to further validate the efficacy and limitations of transradial access for neurointerventional procedures.

Status of SARS-CoV-2 in cerebrospinal fluid of patients with COVID-19 and stroke.

BACKGROUND: Emergence of the novel corona virus (severe acute respiratory syndrome (SARS)-CoV-2) in December 2019 has led to the COVID-19 pandemic. The extent of COVID-19 involvement in the central nervous system is not well established, and the presence or the absence of SARS-CoV-2 particles in the cerebrospinal fluid (CSF) is a topic of debate. CASE DESCRIPTION: We present two patients with COVID-19 and concurrent neurological symptoms. Our first patient is a 31-year-old man who had flu-like symptoms due to COVID-19 and later developed an acute-onset severe headache and loss of consciousness and was diagnosed with a Hunt and Hess grade 3 subarachnoid haemorrhage from a ruptured aneurysm. Our second patient is a 62-year-old woman who had an ischaemic stroke with massive haemorrhagic conversion requiring a decompressive hemicraniectomy. Both patients' CSF was repeatedly negative on real-time PCR analysis despite concurrent neurological disease. CONCLUSION: Our report shows that patients' CSF may be devoid of viral particles even when they test positive for COVID-19 on a nasal swab. Whether SARS-CoV-2 is present in CSF may depend on the systemic disease severity and the degree of the virus' nervous tissue tropism and should be examined in future studies.

Endovascular robotic: feasibility and proof of principle for diagnostic cerebral angiography and carotid artery stenting.

BACKGROUND: Robots in surgery aid in performing delicate, precise maneuvers that humans, with inherent physical abilities, may be limited to perform. The CorPath 200 system is FDA approved and is being implemented in the US for interventional cardiology procedures. CorPath GRX robotic-assisted platform is the next-generation successor of CorPath 200. OBJECTIVE: To discuss the feasibility and early experience with the use of the CorPath GRX robotic-assisted platform for neuroendovascular procedures, including transradial diagnostic cerebral angiograms and transradial carotid artery stenting. METHODS: The cases of 10 consecutive patients who underwent neuroendovascular robotic-assisted procedures between December 1, 2019 and December 30, 2019, are presented. RESULTS: Seven patients underwent elective diagnostic cerebral angiography, and three patients underwent carotid artery angioplasty and stenting using the CorPath GRX robotic-assisted platform. All procedures were performed successfully, and no complications were encountered. Conversion to manual control occurred in three diagnostic cases because of a bovine arch that was previously not known. The fluoroscopy time and the procedure time continued to improve with subsequent procedures as we streamlined the workflow. CONCLUSION: This series demonstrates the early use of this technology. It could potentially be used in the near future for acute stroke interventions in remote geographic locations and in places where a neurointerventionalist is not available.

A novel self-expanding primarily bioabsorbable braided flow-diverting stent for aneurysms: initial safety results.

INTRODUCTION: The advent of metal flow-diverting stents has provided neurointerventionalists with an option for treating aneurysms without requiring manipulations within the aneurysm sac. The large amount of metal in these stents, however, can lead to early and late thrombotic complications, and thus requires long-term antiplatelet agents. Bioabsorbable stents have been postulated to mitigate the risk of these complications. Here we present early data on the first self-expandable primarily bioabsorbable stent for aneurysms. METHODS: Braided stents were developed using poly-L-lactic acid fibers with material surface area similar to metal flow diverters. Crush resistance force, hemolysis, and thrombogenicity were determined and compared with existing commercial devices. Stents were deployed in infra-renal rabbit aortas to determine angiographic side branch patency and to study neointima formation for a 1-month follow-up period. RESULTS: Crush resistance force was determined to be on the order of existing commercial devices. Hemolytic behavior was similar to existing metal devices, and thrombogenicity was lower than metal flow-diverting stents. A smooth neointimal layer was found over the absorbable stent surface and all covered side branches were patent at follow-up. CONCLUSION: The design of self-expanding primarily bioabsorbable flow-diverting stents is possible, and preliminary safety data is consistent with a favorable profile in terms of mechanical behavior, hemocompatibility, side branch patency, and histological effects. Additional in vitro and long-term in vivo studies are in progress and will help determine aneurysm occlusion rates and absorption characteristics of the stent.

Mesenchymal Stem Cells Exhibit Both a Proinflammatory and Anti-Inflammatory Effect on Saccular Aneurysm Formation in a Rabbit Model.

Several studies have demonstrated a potential interaction between mesenchymal stem cells (MSCs) and saccular aneurysms. In this study, we sought to determine whether allogenic bone marrow-derived MSCs had the ability to prevent aneurysm formation in a known rabbit elastase aneurysm model. MSCs were injected intravenously in experimental rabbits at the time of surgical creation and two weeks postcreation and compared with control rabbits receiving vehicle injection. Angiography was used to compare aneurysm measurements four weeks postcreation, and aneurysms were harvested for histological properties. Serum was collected longitudinally to evaluate cytokine alterations. Serum from control animals was also utilized to perform in vitro tests with MSCs to compare the effect of the serologic environment in animals with and without aneurysms on MSC proliferation and cytokine production. While aneurysm morphometric comparisons revealed no differences, significant cytokine alterations were observed in vitro and in vivo, suggesting both anti-inflammatory and proinflammatory processes were occurring in the presence of MSCs. Histological analyses suggested that tunica intima hyperplasia was inhibited in the presence of MSCs.

Risk of Stroke in Patients With Ocular Arterial Occlusive Disorders: A Retrospective Canadian Study.

Background Monocular vision loss, attributed to either central retinal artery occlusion ( CRAO ), branch retinal artery occlusion ( BRAO ), or ocular ischemic syndrome ( OIS ), is thought to be associated with an increased prevalence of cerebral infarcts. However, there is a paucity of data substantiating this. We aimed to investigate this relationship in a Canadian center and further understand the importance of associated internal carotid artery stenosis in potential clinical decision making. Methods and Results We performed a retrospective cohort study at a comprehensive stroke center of patients presenting initially with CRAO , BRAO , or OIS to a centralized ophthalmology center over a 5-year period. Patients were followed for 3 years for the occurrence of a hemispheric stroke. We identified 83 affected eyes, with 31 CRAO , 35 BRAO , and 17 OIS patients. Before ocular diagnosis, 32.3%, 11.4%, and 41.2% of CRAO , BRAO , and OIS patients, respectively, experienced a symptomatic stroke. Of the remaining patients, 4.8%, 12.9%, and 40%, respectively, suffered a hemispheric stroke within 3 years of ocular diagnosis. Logistic regressions suggested that for CRAO and BRAO patients together, the degree of ipsilateral internal carotid artery stenosis is unable to predict the occurrence of a stroke ( P=0.18), whereas our model correctly predicted a stroke in 82.4% of OIS patients ( P=0.005). Conclusions CRAO , BRAO , and OIS are associated with significantly increased symptomatic stroke rates. Degree of ipsilateral internal carotid artery stenosis may not be useful in risk stratification for these patients, suggesting that they should be triaged appropriately for stroke risk-factor management, independent of internal carotid artery stenosis.

A refined experimental model of fusiform aneurysms in a rabbit carotid artery.

OBJECTIVE: Reliable animal models are an important aspect of translational research, especially for relatively uncommon clinical entities such as fusiform aneurysms. While several animal models exist, very few are tailored to cerebral fusiform aneurysms, which have unique attributes compared to abdominal fusiform aneurysms. The authors aimed to build from previous models to create a cerebral fusiform aneurysm model that is simple to use and reliable. METHODS: Twelve female New Zealand White rabbits were assigned to 3 groups: group E, elastase only; group C, CaCl2 only; group EC, elastase + CaCl2. All rabbits underwent surgical exposure of the right common carotid artery (CCA) and 20 minutes of peri-carotid incubation with their respective chemicals. Angiography was performed 6 weeks later for arterial dilation measurements, with 50% increase in diameter being defined as fusiform aneurysm formation. The arterial segments, along with the contralateral CCAs, were harvested and assessed histologically for wall component measurements and elastin semiquantification. A separate rabbit underwent aneurysm creation per the group EC protocol and was treated with an endovascular flow-diversion device. RESULTS: All of the group EC rabbits developed fusiform aneurysms (mean dilation of 88%), while none of the group E or group C rabbits developed aneurysms (p = 0.001). Histological analysis revealed increased internal elastic lamina fragmentation in the group EC aneurysms, which also had less tunica intima hyperplasia. All aneurysms exhibited thinning of the tunica media and reduction in elastin content. The use of an endovascular flow-diverting stent was successful, with complete parent vessel remodeling, as expected, 4 weeks after deployment. CONCLUSIONS: The peri-arterial application of combined elastase and CaCl2 to the CCA appears sufficient to reliably produce fusiform aneurysms after 6 weeks. Exposure to elastase or CaCl2 individually appears insufficient, despite the observed histological changes to the arterial wall. The proposed fusiform aneurysm model is able to accommodate endovascular devices, simulating the tortuous pathway experienced in using such devices in human cerebral aneurysms and thus is a satisfactory model to use in translational research.

Accuracy and precision of venous pressure measurements of endovascular microcatheters in the setting of dural venous sinus stenosis.

INTRODUCTION: Dural venous sinus stenosis (DVSS) may lead to increased intracranial pressure, sometimes requiring a stent if a high pressure gradient exists. Many neuroendovascular physicians use microcatheters to measure gradients, yet there are no studies comparing the accuracies and precisions of modern day microcatheters. We examined pressure recordings from five commonly used microcatheters in an experimental DVSS model. METHODS: Using a programmable pump, dynamic flow was established in a closed circuit mimicking the venous sinus waveform. Microcatheters with 150 cm effective lengths were connected proximally to pressure transducers. Mean recording pressures were compared with a high fidelity microcatheter (HFM) in several configurations including no stenosis, proximal to a focal stenosis, and distal to a focal stenosis in opposing orientations. RESULTS: All microcatheters recorded lower pressures than the HFM. Three of the five microcatheters successfully met intracranial pressure monitoring device standards in all conditions, while one did not meet standards in any configuration. The performance of the final microcatheter was variable, with inaccuracies occurring in unrestricted flow. All microcatheters demonstrated relatively high precision, but with variable accuracies. The larger diameter microcatheters displayed the least damping and therefore the greatest accuracies. Of the three smaller microcatheters, dimensions did not predict performance, suggesting that microcatheter construction may also play a role in pressure accuracy. CONCLUSION: The use of microcatheters to record dural venous sinus pressures must be done with an understanding of the inherent limitations and inaccuracies, especially if clinical decisions are made from the results.

Utility of perfusion imaging in acute stroke treatment: a systematic review and meta-analysis.

BACKGROUND: Variability in imaging protocols and techniques has resulted in a lack of consensus regarding the incorporation of perfusion imaging into stroke triage and treatment. The objective of our study was to evaluate the available scientific evidence regarding the utility of perfusion imaging in determining treatment eligibility in patients with acute stroke and in predicting their clinical outcome. METHODS: We performed a systematic review of the literature using PubMed, Web of Science, and Cochrane Library focusing on themes of medical imaging, stroke, treatment, and outcome (CRD42016037817). We included randomized controlled trials, cohort studies, and case-controlled studies published from 2011 to 2016. Two independent reviewers conducted the study appraisal, data abstraction, and quality assessments of the studies. RESULTS: Our literature search yielded 13 studies that met our inclusion criteria. In total, 994 patients were treated with the aid of perfusion imaging compared with 1819 patients treated with standard care. In the intervention group 51.1% of patients had a favorable outcome at 3 months compared with 45.6% of patients in the control group (p=0.06). Subgroup analysis of studies that used multimodal therapy (IV tissue plasminogen activator, endovascular thrombectomy) showed a significant benefit of perfusion imaging (OR 1.89, 95% CI 1.43 to 2.51, p<0.01). CONCLUSIONS: Perfusion imaging may represent a complementary tool to standard radiographic assessment in enhancing patient selection for reperfusion therapy, with a subset of patients having up to 1.9 times the odds of achieving independent functional status at 3 months. This is particularly important as patients selected based on perfusion status often included individuals who did not meet the current treatment eligibility criteria.