Risk Factors for Distal Clot Migration during Mechanical Thrombectomy of Anterior Circulation Large Vessel Occlusion.

INTRODUCTION: Distal clot migration (DCM) is a known complication of mechanical thrombectomy (MT), but neither risk factors for DCM nor ways of how it might affect clinical outcomes have been extensively studied to date. METHODS: To identify risk factors for and outcomes in the setting of DCM, the records of all patients with acute ischemic stroke due to anterior circulation large vessel occlusion (LVO) treated with MT at a single center between May 2016 and June 2018 were retrospectively reviewed. Uni- and multivariable analyses were performed to evaluate predictors of DCM and good functional outcome (90-day modified Rankin Scale; mRS 0-2). RESULTS: A total of 65 patients were included, DCM was identified in 22 patients (33.8%). Patients with DCM had significantly higher pre-procedural intravenous tissue plasminogen activator (IV-tPA) administration (81.8 vs. 53.5%, p = 0.03), stentrievers thrombectomy (95.5 vs. 62.8%, p = 0.006), and longer median puncture to recanalization time (44 [34-97] vs. 30 [20-56] min, p = 0.028) as compared to group with non-DCM. Also, they had lower rates of Thrombolysis in Cerebral Infarction (TICI) 2b/3 recanalization (p = 0.002), higher median National Institutes of Health Stroke Scale (NIHSS) scores at discharge (p = 0.01), and lower rates of 90-day mRS (0-2; 18.2 vs. 48.8%; p = 0.016). On subgroup analysis, patients with middle cerebral artery occlusions who underwent MT with stentrievers <40 mm in length had a higher risk of DCM (p = 0.026). On multivariable analysis, IV-tPA administration (OR; 5.019, 95% CI [1.319-19.102], p = 0.018) and stentrievers thrombectomy (OR; 10.031, 95% CI [1.090-92.344]; p = 0.04) remained significant predictors of DCM. Baseline NIHSS score (OR; 0.872, 95% CI [0.788-0.965], p = 0.008) and DCM (OR; 0.250, 95% CI [0.075-0.866], p = 0.03) were independent predictors of 90-day mRS 0-2. CONCLUSION: In patients undergoing MT for anterior circulation LVO, DCM is associated with lower rates of TICI 2b/3 recanalization and worse functional outcomes at 90 days. IV-tPA administration and MT with short stentrievers are independent predictors of DCM development.

Treatment of unstable thoracolumbar junction fractures: short-segment pedicle fixation with inclusion of the fracture level versus long-segment instrumentation.

BACKGROUND: The surgical management of thoracolumbar burst fractures frequently involves posterior pedicle screw fixation. However, the application of short- or long-segment instrumentation is still controversial. The aim of this study was to compare the outcome of the short-segment fixation with inclusion of the fracture level (SSFIFL) versus the traditional long-segment fixation (LSF) for the treatment of unstable thoracolumbar junction fractures. METHODS: From December 2009 to February 2014, 60 patients with unstable thoracolumbar junction fractures (T11-L2) were divided into two groups according to the number of instrumented levels. Group 1 included 30 patients treated by SSFIFL (six-screw construct including the fracture level). Group 2 included 30 patients treated by LSF (eight-screw construct excluding the fracture level). Local kyphosis angle (LKA), anterior body height (ABH), posterior body height (PBH), ABH/PBH ratio of fractured vertebra, and Asia Scale Impairment Scale were evaluated. RESULTS: The two groups were similar in regard to age, sex, trauma etiology, fracture level, fracture type, neurologic status, pre-operative LKA, ABH, PBH, and ABH/PBH ratio and follow-up (p > 0.05). Reduction of post-traumatic kyphosis (assessed with LKA) and restoration of fracture-induced wedge shape of the vertebral body (assessed with ABH, PBH, and ABH/PBH ratio) at post-operative period were not significantly different between group 1 and group 2 (p = 0.234; p = 0.754). There was no significant difference between the two groups in term of correction loss at the last follow-up too (LKA was 15.97° ± 5.62° for SSFIFL and 17.76° ± 11.22° for LSF [p = 0.427]). Neurological outcome was similar in both groups. CONCLUSIONS: Inclusion of fracture level in a short-segment fixation for a thoracolumbar junction fractures results in a kyphosis correction and in a maintenance of the sagittal alignment similar to a long-segment instrumentation. Finally, this technique allowed us to save two or more segments of vertebral motion.

The correlation of cerebral arteriovenous malformation flow measured by quantitative MR angiography on MR-detected arteriovenous malformation microhemorrhage.

OBJECTIVE: The objective of this study was to assess the relationship of arteriovenous malformation (AVM) blood flow measured by quantitative MR angiography (QMRA) in nonruptured AVMs with MR-detected microhemorrhage. METHODS: All patients with unruptured AVMs who received baseline QMRA and gradient echo or susceptibility-weighted MRI were retrospectively reviewed (2004-2022). Imaging data, clinical history, and AVM angioarchitectural and flow features were collected and assessed. AVM flow was calculated from the difference of flow within primary arterial feeders from their contralateral counterparts. A review of the MR images determined the presence of microhemorrhages. Analysis of descriptive statistics, chi-square test, and binomial logistic regression were performed. RESULTS: Of 634 patients with cerebral AVMs at a single center, 89 patients met the inclusion criteria (54 with microhemorrhage and 35 without microhemorrhage). The calculated AVM flow was significantly higher in the group with a microhemorrhage (447.9 ± 193.1 ml/min vs 287.6 ± 235.7 ml/min, p = 0.009). In addition, the presence of venous anomaly, arterial ectasia, and diffuse nidus was significantly associated with microhemorrhage (p = 0.017, p = 0.041, and p = 0.041, respectively). Binary logistic regression found that higher flow predicted the presence of microhemorrhage (OR 1.002, 95% CI 1.000-1.004; p = 0.031). The highest AVM flow quartile significantly predicted the presence of venous anomaly (OR 3.840, 95% CI 1.037-14.213; p = 0.044), diffuse nidus (OR 6.800, 95% CI 1.766-25.181; p = 0.005), and arterial ectasia (OR 13.846, 95% CI 1.905-122.584; p = 0.018). CONCLUSIONS: This study represents the first to examine the association between flow measurements on QMRA with microhemorrhage in unruptured AVMs. Higher AVM flow, venous anomaly, arterial ectasia, and diffuse AVM nidus were related to a higher likelihood of AVM microhemorrhage. Higher AVM flow was present in AVMs with venous anomalies, a diffuse nidus, and arterial ectasia, indicating a possible interaction between these angioarchitectural findings, AVM flow, and microhemorrhage. These findings suggest a relationship between higher AVM flow and the risk of microhemorrhage.

Approaches to ventriculoperitoneal shunt scalp erosion: countersinking into the calvarium. Illustrative case.

BACKGROUND: Ventriculoperitoneal shunting (VPS) is a standard procedure for the treatment of hydrocephalus, and the management of its complications is common in the practice of pediatric neurosurgery. Shunt exposure, though a rare complication, can occur because of thin, fragile skin, a young patient age, protuberant hardware, poor scalp perfusion, and a multitude of other patient factors. OBSERVATIONS: The authors report a complex case of VPS erosion through the scalp in a young female with Pfeiffer syndrome treated with external ventricular drainage, empirical antibiotics, and reinternalization with countersinking of replaced shunt hardware into the calvarium to prevent internal skin pressure points, reduce wound tension, and allow wound healing. LESSONS: Recessing the shunt hardware, or countersinking the implant, into the calvarium is a simple technique often used in functional neurosurgical implantation surgeries, providing a safe surgical strategy to optimize wound healing in select cases in which the skin flap is unfavorable.

Preoperative embolization of brain arteriovenous malformation and efficacy in intraoperative blood loss reduction: a quantitative study.

BACKGROUND: Embolization of brain arteriovenous malformations (bAVMs) is often used as adjuvant therapy to microsurgical resection to reduce the high-risk features of bAVMs such as large size and high flow. However, the effect of preoperative embolization on surgical performance and patient outcome has shown mixed results. Heterogeneity in treatment goals, selection criteria, and unpredictable changes in bAVM hemodynamics after partial embolization may account for these uncertain findings. In this study we use an objective quantitative technique to assess the impact of preoperative embolization on intraoperative blood loss (IBL). METHODS: Patients with bAVM treated with microsurgical resection only or in combination with preoperative embolization from 2012 to 2022 were retrospectively reviewed. Patients were included if quantitative magnetic resonance angiography was performed prior to any treatment. Correlation of baseline bAVM flow, volume, and IBL was evaluated between the two groups. Additionally, bAVM flow prior to and after embolization was compared. RESULTS: Forty-three patients were included, 31 of whom required preoperative embolization (20 had more than one session). Mean bAVM initial flow (362.3 mL/min vs 89.6 mL/min, p=0.001) and volume (9.6 mL vs 2.8 mL, p=0.001) were significantly higher in the preoperative embolization group; flow decreased significantly after embolization (408.0 mL/min vs 139.5 mL/min, p<0.001). IBL was comparable between the two groups (258.6 mL vs 141.3 mL, p=0.17). Linear regression continued to show a significant difference in initial bAVM flow (p=0.03) but no significant difference in IBL (p=0.53). CONCLUSION: Patients with larger bAVMs who underwent preoperative embolization had comparable IBL to those with smaller bAVMs undergoing only surgical treatment. Preoperative embolization of high-flow bAVMs facilitates surgical resection, reducing the risk of IBL.

Quantitative Blood Flow Reduction in Selective Embolization of Intranidal Fistula of Cerebral Arteriovenous Malformations: Case Series.

BACKGROUND AND OBJECTIVES: Arteriovenous malformations (AVMs) are often associated with high-flow intranidal fistulas (INFs). Although INF embolization has been suggested to provide higher reduction of total AVM flow compared with regular pedicle embolization, this effect has not previously been quantified. The aim of this study was to characterize the effect of AVM INF embolization on total AVM flow. METHODS: This study is an Institutional Review Board-approved, retrospective case series of patients from 2010 to 2022 with AVMs, both with and without INFs, who underwent quantitative magnetic resonance angiography and endovascular embolization. RESULTS: Twenty patients accounted for 35 separate embolization sessions: 13 patients with INFs underwent a total 21 embolizations and 12 patients without INFs had 14 embolizations. No significant differences were found between groups on age, sex, laterality, drainage pattern, and Spetzler-Martin grade. However, AVMs with INFs were larger than the control group (12.7 vs 8.37 cm 3 , P = .049). Baseline pre-embolization AVM flow significantly differed between AVM with INF vs control groups (522 vs 320 cc/min, P = .005). Similarly, postembolization AVM flow also differed between AVM with INF and control groups (392 vs 224 cc/min, P = .008), with a larger decrease in flow per vessel per embolization session within the AVM INF group compared with controls (101.5 vs 33.2 cc/min, P < .001). Repeated measure analysis of variance showed significant differences pre-embolization and postembolization AVM flow between those with INFs vs controls ( P < .001). CONCLUSION: This study represents the first to examine the effect of INF embolization on total AVM flow. AVMs with INFs showed higher baseline flow, and targeted embolization toward INFs significantly lowered AVM flow in comparison with controls without INFs. The results of this study emphasize the importance of recognizing the presence of INFs within AVMs and their embolization to reduce AVM flow as part of a multistep management paradigm.

Brain arteriovenous malformation flow after stereotactic radiosurgery: Role of quantitative MRA.

BACKGROUND: Stereotactic radiosurgery (SRS) is a current therapeutic option for treatment of arteriovenous malformations (AVMs) located in deep or eloquent brain regions. Obliteration usually occurs in a delayed fashion, with an expected latency of 3-5 years. Here, we assess how AVM flow correlates with volume before and after SRS treatment. METHODS: Patients with supratentorial AVM treated with SRS at our institution between 2012-2022 were retrospectively reviewed. Patients were included if Quantitative Magnetic Resonance Angiography (QMRA) study was performed at baseline and at least at the first follow-up. Correlation between AVM flow and volume before and after treatment was evaluated. AVM flow and volume were additionally assessed for obliteration using the non-parametric receiver operating characteristic (ROC) curve. RESULTS: Twelve patients with radiologic follow-up imaging were included. Eight patients presented AVM rupture, one of which occurred after radiosurgical treatment. Three patients underwent embolization prior SRS. Mean AVM initial volume was 3.8 cc (0.1-12.4 cc), mean initial flow 174 ml/min (11-604 ml/min), both variables showed progressive reduction at follow-up (range 3-57 months); and flow decreased with volume reduction (p < 0.001). Area under the ROC was 0.914 for both AVM flow and volume with obliteration (p = 0.019). CONCLUSIONS: AVM flow significantly decreased after SRS treatment, reflecting volume reduction. Baseline AVM flow and volume both predicted obliteration. QMRA provides additional non-invasive information to monitor patients after radiosurgical treatment.

Impact of cerebral aneurysm size on distal intracranial hemodynamics and changes following flow diversion.

BACKGROUND: The impact of cerebral aneurysm size on distal intracranial hemodynamics such as arterial pressure and Pulsatility Index is not completely understood, either before or after flow diversion. OBJECTIVE: The aim of the study is to assess the impact of aneurysm size on distal Pulsatility Index and pressure before and after flow diversion. METHODS: From December 2015, prospective measurement of middle cerebral artery pressure and Pulsatility Index was performed in consecutive patients with unruptured cerebral aneurysms in the cavernous to communicating segments of the internal carotid artery, which were treated with single flow diversion. Pressure and Pulsatility Index were recorded at the M1-segment ipsilateral to the cerebral aneurysm. Ratio of middle cerebral artery to radial arterial pressure (pressure ratio) was calculated to control for variations in systemic blood pressure. Correlations between aneurysm size and pressure ratio and Pulsatility Index were assessed before and after treatment. RESULTS: A total of 28 aneurysms were treated. The mean aneurysm size was 7.2 mm. Aneurysm size correlated linearly with systolic pressure ratio (1% pressure ratio increase per mm aneurysm size increase, P = 0.002, r2 = 0.33), mean pressure ratio (0.6% per mm, P = 0.03, r2 = 0.17) and Pulsatility Index (5% Pulsatility Index increase per mm, P = 0.003, r2 = 0.43). After flow diversion, aneurysm size preserved a linear correlation with the systolic pressure ratio (1% per mm, P = 0.004, r2 = 0.28), but not with the mean pressure ratio (0.4% per mm, P = 0.15, r2 < 0.1) or Pulsatility Index (0.3% per mm, P = 0.78, r2 < 0.1). CONCLUSION: Aneurysm size affects distal hemodynamics: patients with larger aneurysms have increased systolic and mean pressure ratio, and increased Pulsatility Index. After flow diversion, mean pressure ratio and Pulsatility Index no longer associate with the aneurysm size, suggesting an effect of the flow diversion also on distal intracranial hemodynamics.

Vessel wall imaging and quantitative flow assessment in arteriovenous malformations: A feasibility study.

INTRODUCTION: Cerebral arteriovenous malformations (AVMs) carry a rupture rate of 2-3% per year. Several architectural factors may influence rupture rate, and a recently theorized model of AVMs describes the influence of vessel wall inflammation. A novel imaging modality, vessel wall imaging (VWI), has been developed to view inflammatory processes in vessel wall foci but has not yet been examined in AVMs, which is the aim of this study. METHODS: This retrospective review studies prospectively collected data on patients with ruptured and unruptured AVMs between 2019 and 2021. Inclusion criteria included adult patients (≥18 years) with radiographically diagnosed AVM who underwent VWI. Charts were reviewed for medical history, clinical presentation, hospital course, discharge condition, and follow-up. Angioarchitectural features, blood flow, and VWI were compared in patients with and without hemorrhagic patients. RESULTS: Nine patients underwent VWI, mean age 37.7 ± 9.9 years. Four presented with hemorrhage (44.4%). Seven (77.7%) received glue embolization and 6 (66.7%) underwent surgical resection. All patients (4/4) with a history of hypertension presented with hemorrhage (p = 0.0027). Size and Spetzler-Martin grade were not associated with hemorrhage (p = 0.47, p = 0.59). Net AVM flow was higher in patients presenting with hemorrhage, although nonsignificant (p = 0.19). With VWI, 3 (75%) hemorrhagic AVMs showed visible nidus and draining veins, and all three demonstrated positive post-contrast wall enhancement in at least one of their draining veins; conversely, of fivenonhemorrhagic AVMs, only 2 (40%) demonstrated post-contrast wall enhancement in any draining vein (p = 0.090). CONCLUSION: This pilot study successfully demonstrated capture of venous walls in AVMs using VWI. In this study, draining vein enhancement occurred more often in hemorrhagic AVM and in those with higher venous volumetric flow.

Operative Nuances of Blind Catheterization of Occluded Sinuses Using Negative Road Map Technique: 2-Dimensional Operative Video.

Dural arteriovenous fistula (DAVF) are often treated with endovascular transvenous embolization. DAVFs though, are often associated with intracranial venous sinus occlusion, which limits the transvenous route. Here, we present the operative nuances of blind catheterization of an occluded dural venous sinus in 2 different cases with DAVF. First case is a 72-yr-old patient with indirect right carotid-cavernous fistula associated with an occluded inferior petrosal sinus, with severe orbital congestion. Second patient is a 79-yr-old patient with a new external carotid to a trapped transverse sinus fistula (Cognard IIA + B), extensive cortical venous reflux in the setting of an occluded sigmoid sinus. In both cases, the transarterial route was limited because of small arterial feeders thus, after obtaining patients' consent, we performed transvenous sacrifice of the isolated sinus. In both cases, the occluded sinus was transvenously blindly retrograde probed using a 0.035 inch Terumo Glidewire (Terumo Medical Corporation, Somerset, New Jersey). Once the occluded segment was probed, a dark roadmap was acquired with the wire in place. This created a negative roadmap once the guidewire is removed. This negative roadmap is used to navigate the microcatheter-microwire into the isolated sinus. In the first case, the cavernous sinus and the superior ophthalmic veins were sacrificed with coils. In the second patient, the entrapped left transverse sinus was embolized using Onyx. In both cases, complete occlusion of the fistula was attained. In this neuroendovascular video, we demonstrate the nuances of blind catheterization of an occluded sinus using a negative roadmap technique as guidance for the micro-catheterization. Institutional Review Board approved. Patient consent not required due to retrospective nature of manuscript, based on medical chart and imaging reviews, anonymized in the video.

Intracranial venous sinus stenosis: hemodynamic assessment with two-dimensional parametric parenchymal blood flow software on digital subtraction angiography.

OBJECTIVE: Intracranial venous sinus stenosis (IVSS) is the most common finding associated with idiopathic intracranial hypertension. A pressure gradient >8-10 mm Hg across the stenosis is considered hemodynamically significant, and typically responds to endovascular stent treatment. Here we assess the venous hemodynamics with two-dimensional (2D) parametric parenchymal blood flow software (Siemens-Healthineers, Forchheim, Germany) and its ability to predict significant IVSS. METHODS: Patients with IVSS treated at our institution between 2013 and 2018 were retrospectively reviewed. Measurements of contrast transit time on DSA were calculated with 2D parametric parenchymal blood flow software. Values were obtained proximally and distally to the stenotic region. Venous Stenosis Index (VSI) was defined as the ratio of the area under the curve (AUC) in the pre-stenotic vessel to the AUC in the post-stenotic vessel. VSI was compared between the stenotic and control groups at baseline, and before and after stent deployment in the stenotic group. The accuracy of VSI was assessed using the non-parametric receiver operating characteristic (ROC) curve. RESULTS: 11 patients with IVSS treated with venous stent deployment were included. Patients in the control group were similar in age, gender, and absence of major comorbidities. VSI in the IVSS group was significantly higher at baseline compared with the control group (1.42 vs 0.97, p=0.01). Area under the ROC was 0.82. After stent deployment, VSI decreased significantly compared with baseline (1.04 vs 1.42, p<0.01). CONCLUSION: 2D parametric parenchymal blood flow software is a useful tool which can accurately evaluate significant hemodynamic venous stenosis without intracranial catheterization, added radiation exposure, additional contrast injection, and periprocedural risks.

Predictors of Poor Outcome Despite Successful Mechanical Thrombectomy of Anterior Circulation Large Vessel Occlusions Within 6 h of Symptom Onset.

Background and Purpose: Successful reperfusion is a significant predictor of a good clinical outcome after mechanical thrombectomy (MT). However, some patients have a poor clinical outcome even with successful reperfusion. We aimed to study factors that predict a poor clinical outcome (90-day modified Rankin Scale ≥ 3) in patients with anterior circulation large vessel occlusion (LVO) treated by successful MT within 6 h of symptom onset. Methods: We performed a retrospective review of a prospectively maintained MT database of all patients who underwent MT within 6 h of symptom onset for an anterior circulation LVO at our institution from May 2016 to June 2018. Uni- and multivariable analyses were performed to identify predictors of poor outcome. Results: A total of 56 patients met the criteria for inclusion in this study. A poor outcome occurred in 31 (55.4%) patients. On univariate analysis, compared to patients with good clinical outcome, patients with poor outcome had higher mean baseline NIHSS scores (23.3 vs. 13.8, P < 0.001), were more likely to have internal carotid artery (ICA) occlusions (38.7 vs. 8%, P = 0.008), and had a higher incidence of distal clot migration (DCM) (48.4 vs. 8%, P = 0.028). Age, gender, other baseline clinical characteristics, MT technique, and incidence of hemorrhagic transformation did not differ between the two cohorts. On multivariable regression analysis, baseline NIHSS score [OR; 1.3, 95%CI [1.11-1.52], P = 0.001], site of occlusion (ICA) [OR; 8.9, 95%CI [1.3-60.9], P = 0.026], and DCM [OR; 5.77, 95%CI [1.09-30.69], P = 0.04] were independent predictors of poor outcome at 90-days. Conclusion: Baseline NIHSS score, ICA occlusion, and DCM are independent predictors of a poor outcome after MT for anterior circulation LVO performed within 6 h of symptoms onset.

2D parametric contrast time-density analysis for the prediction of complete aneurysm occlusion at six months' post-flow diversion stent.

OBJECTIVE: Indications for the treatment of cerebral aneurysms with flow diversion stents are expanding. The current aneurysm occlusion rate at six months ranges between 60 and 80%. Predictability of complete vs. partial aneurysm occlusion is poorly defined. Here, we evaluate the angiographic contrast time-density as a predictor of aneurysm occlusion rate at six months' post-flow diversion stents. METHODS: Patients with unruptured cerebral aneurysms proximal to the internal carotid artery terminus treated with single flow diversion stents were included. 2D parametric parenchymal blood flow software (Siemens-Healthineers, Forchheim, Germany) was used to calculate contrast time-density within the aneurysm and in the proximal adjacent internal carotid artery. The area under the curve ratio between the two regions of interests was assessed at baseline and after flow diversion stents deployment. The area under the curve ratio between completely vs. partially occluded aneurysms at six months' follow-up was compared. RESULTS: Thirty patients with 31 aneurysms were included. Mean aneurysm diameter was 8 mm (range 2-28 mm). Complete occlusion was obtained in 19 aneurysms. Younger patients (P = 0.006) and smaller aneurysms (P = 0.046) presented higher chance of complete obliteration. Incomplete occlusion of the aneurysm was more likely if the area under the curve contrast time-density ratio showed absolute (P = 0.001) and relative percentage (P = 0.001) decrease after flow diversion stents deployment. Area under ROC curve was 0.85. CONCLUSION: Negative change in the area under the curve ratio indicates less contrast stagnation in the aneurysm and lower chance of occlusion. These data provide a real-time analysis after aneurysm treatment. If validated in larger datasets, this can prompt input to the surgeon to place a second flow diversion stents.

Role of Resistivity Index Analysis in the Prediction of Hemodynamically Significant Venous Sinus Stenosis in Patient With Idiopathic Intracranial Hypertension.

BACKGROUND: The resistivity index (RI) in cerebral venous sinus stenosis (VSS) has not been studied in patients with idiopathic intracranial hypertension (IIH). OBJECTIVE: To evaluate the role of RI measured by quantitative magnetic resonance venogram (QMRV) as a noninvasive tool in the diagnosis of venous hypertension associated with VSS in IIH. METHODS: Retrospective evaluation of 13 consecutive IIH patients who underwent venous sinus stenting at our institution between 2013 and 2018.Patients' demographics, clinical presentation, cerebral mean venous sinus pressure (MVP), and RI both pre- and poststenting were recorded. The baseline RI was also compared to a control group. RESULTS: Among 13 patients of IIH, 11 had unilateral VSS in dominant sinus, whereas 2 had bilateral VSS. RI was significantly higher in IIH patients compared to the control group in the superior sagittal (SSS) and transverse sinuses (TS) (0.21 vs 0.11, P = .01 and 0.22 vs 0.13, P = .03, respectively). The MVP (in mm Hg) decreased significantly after venous sinus stenting in the SSS (41.9 to 22.5, P < .001) and TS (39.4 to 19.5, P < .001), which was also associated with a significant reduction of the RI (0.22 vs 0.17, P < .01 in SSS and 0.23 vs 0.17, P = .03 in TS) poststenting. CONCLUSION: RI calculated using QMRV can serve as a noninvasive tool to aid in the diagnosis of hemodynamically significant VSS. The study had a small sample size, and larger multicenter studies would be required to validate the results further.

Embolization of a Complex Facial Arteriovenous Malformation, Balloon-Assisted Flow Arrest, and Controlled n-BCA Injection with Dextrose Push Technique: 2-Dimensional Operative Video.

N-butyl cyanoacrylate glue (n-BCA, Cerenovus, Irvine, California) is commonly used to treat arteriovenous malformation (AVM). Even though Onyx (ethylene vinyl alcohol, Medtronic, Dublin, Ireland) presents more controlled injection, n-BCA is colorless, thus preferable for treatment of superficial facial malformations. N-BCA injection into AVM can result in premature distal migration or early precipitation and reflux into the feeder vessels. Here we describe a trans-arterial balloon assisted technique embolization of a complex facial AVM with n-BCA. A 22-yr-old female with chronic oral/gum bleeding presented with a complex facial AVM. She underwent selective transarterial n-BCA balloon assisted treatment with dextrose push. Informed written consent was obtained. A Scepter dual lumen balloon (MicroVention, Aliso Viejo, California) and a Prowler microcatheter (Cerenovus) were introduced via a 6-French Envoy guide catheter (Cerenovus) selectively into the AVM feeder. The balloon was positioned 3 cm proximal to the Prowler microcatheter tip and fully inflated to create flow arrest. Diluted 25% concentration of n-BCA in Ethiodol Oil was injected through the Prowler microcatheter. The distal migration of the n-BCA was modulated with simultaneous injection of Dextrose 5% in water via the Scepter balloon. This resulted in a controlled glue injection without early distal glue migration (because of the flow arrest) nor early proximal glue precipitation or reflux (because of the dextrose infusion), obtaining complete cure of the complex facial AVM. Glue embolization with flow arrest and dextrose push allows well controlled injection, and it represents a valid option also for high flow vascular lesions.

Glue Embolization with Guide Catheter Dextrose Push of Recurrent Dural Arteriovenous Fistula Previously Embolized with Onyx: Neuroendovascular Surgical Video.

Onyx (ethylene vinyl alcohol, ev3, Irvine, California, USA) is commonly used to treat dural arteriovenous fistulas (DAVFs) and presents several advantages over n-butyl cyanoacrylate glue (Codman Neurovascular Inc, Raynham, Massachusetts, USA) including slower, more controlled injections and better penetration via radial casting. However, Onyx is nonthrombogenic and may result in incomplete casting, recanalization, and DAVF recurrence. Here, we demonstrate glue embolization with guide catheter dextrose push of a recurrent DAVF previously embolized with Onyx. A 79-year-old female diagnosed with a Cognard IIA+B DAVF was successfully treated with transarterial Onyx injection. A 6-month follow-up angiogram, however, revealed recurrence of the DAVF with recanalization of the previously embolized draining vein. She subsequently underwent retreatment using glue embolization with a guide catheter dextrose push. Informed written consent was obtained. A Magic microcatheter (Balt Extrusion, Irvine, California, USA) was passed via a 6-French Envoy guide catheter (Codman Neurovascular) in the external carotid artery and was used to select the superficial temporal artery and then navigated distally through a transosseous connection into the dura. A dilute 12.5% concentration of glue was injected slowly and continuously and was seen to fill in spaces within the old Onyx material. Dextrose 5% in water was concomitantly injected through the guide catheter to ensure distal migration of the glue and occlusion of the draining vein. Glue embolization with dextrose push is a valuable treatment option for DAVF, especially in smaller recurrent feeders that can fill in the Onyx recanalized cast. The 6-month follow-up angiogram showed persistent occlusion of the dural fistula (Video 1).

Pipeline Embolization of Giant Cavernous Internal Carotid Artery Aneurysm with Direct Carotid Puncture and Arteriotomy Closure Device: Neuroendovascular Surgical Video.

Flow diversion technology has revolutionized the treatment of complex anterior circulation cerebral aneurysms. However, vessel tortuosity and atherosclerotic disease may hamper the standard transfemoral access used in these procedures. Percutaneous direct carotid puncture is a viable alternative, but adequate carotid closure must be achieved. Here, we present the first case of a giant partially thrombosed aneurysm of the cavernous internal carotid artery treated with a Pipeline embolization device (PED; ev3 Neurovascular, Irvine, California, USA) via direct carotid puncture. A 79-year-old female presented with bilateral giant cavernous internal carotid artery aneurysms. She was successfully treated with PED on the right side and failed treatment with PED on the left side using a transfemoral approach due to common carotid artery tortuosity. She was lost to follow-up but presented 3 years later with worsening left eye pain and ophthalmoplegia. Percutaneous direct carotid puncture was performed under ultrasound guidance, and a 6-French sheath was inserted. Using roadmap guidance, a Marksman microcatheter (ev3 Neurovascular) with the support of a Navien intermediate catheter (ev3 Neurovascular) was advanced into the left middle cerebral artery, and 4 PEDs were deployed within the paraclinoid and cavernous segments of the internal carotid artery to completely cover the neck of the aneurysm. Carotid closure was performed for the first time with a Mynx collagen plug device (AccessClosure, Inc., Mountain View, California, USA). The patient recovered from the procedure without any complications, and her ophthalmoplegia partially improved. Informed patient consent for the procedure and for publication was obtained (Video 1).

Transarterial Glue Embolization and Covered Stenting of Large Carotid Body Tumor in Same Setting: Neuroendovascular Surgical Video.

Surgical resection is considered to be the treatment of choice for carotid body tumors. However, surgery can be complicated by intraoperative bleeding, injury to the internal carotid artery, and cerebral ischemia. Consequently, preoperative endovascular strategies including transarterial or percutaneous embolization or covered carotid stenting may be used. These neuroendovascular techniques have been described infrequently in the literature. Here, we showcase transarterial glue embolization followed by covered carotid stenting of a large carotid body tumor in the same setting (Video 1). A 53-year-old male presented with a 6-cm pulsatile and enlarging neck mass, as well as swallowing difficulty. Craniofacial computed tomography scan and digital subtraction angiography were consistent with a carotid body tumor. It was decided to perform preoperative embolization. Using roadmap guidance, a Prowler microcatheter (Codman Neurovascular, Inc., Raynham, Massachusetts, USA) was navigated into a tumor feeder vessel and a dilute 12% concentration (mix of 1 mL glue, 7 mL ethiodized oil) of the liquid embolic agent N-BCA (N-butyl cyanoacrylate; Codman Neurovascular, Inc.) was injected and seen to cast the tumor. During embolization, dextrose 5% water was injected through the guide catheter to enhance glue penetration into the tumor bed. Then, 2 covered stents (iCAST, Atrium Medical Corporation, Hudson, New Hampshire, USA) were deployed within the cervical internal carotid artery extending from levels C1-C6, spanning the carotid bifurcation, and excluding the external carotid artery. The patient underwent surgical resection 8 weeks later. The patient recovered from the procedures without any complications. Informed consent for the procedure and publication was obtained.

Correlation Between Laminar Wall Shear Stress and Growth of Unruptured Cerebral Aneurysms: In Vivo Assessment.

BACKGROUND: Cerebral aneurysm growth is significantly associated with aneurysm rupture, but risk factors for aneurysm growth are not well characterized. It is believed that altered intracranial hemodynamics may contribute to the pathophysiology of aneurysm growth, but these mechanisms are not fully understood. OBJECTIVE: Here, we assess the correlation between growth of unruptured cerebral aneurysms over time and average laminar shear stress on the wall of the parent vessel proximal to the aneurysm. METHODS: Patients with unruptured, untreated cerebral aneurysms followed over time at our institution between 2005 and 2017 were retrospectively reviewed. Patients were included if at least 1 quantitative magnetic resonance angiography study was performed at baseline and follow-up. The nonparametric Wilcoxon-Mann-Whitney test was used to compare mean parent vessel-laminar wall shear stress (PV-LWSS) proximal to the aneurysm in growing versus stable aneurysms. Change in PV-LWSS over time was evaluated using the 1-way repeated measures analysis of variance test. RESULTS: Thirty-three patients with 45 total aneurysms were included (63% female, mean age 60 years). Four patients presented with aneurysm growth over time. Unstable aneurysms had significantly higher PV-LWSS compared with stable aneurysms at the time of first diagnosis (29.3 vs. 13.1 dynes/cm2, P = 0.02) and at 1-year follow-up (25.8 vs. 12.3 dynes/cm2, P = 0.05). CONCLUSIONS: The subset of unruptured cerebral aneurysms that demonstrate growth over time has a significantly higher mean PV-LWSS than stable aneurysms, as measured by quantitative magnetic resonance angiography. This information at the time of diagnosis may help predict future aneurysm growth, stratify rupture risk, and identify those aneurysms that should undergo prophylactic treatment.

Cerebral arteriovenous malformation venous stenosis is associated with hemodynamic changes at the draining vein-venous sinus junction.

Cerebral arteriovenous malformations (AVMs) are an uncommon vascular anomaly that carry the risk of rupture and hemorrhage. Several factors have been implicated in the propensity of an AVM to bleed. One such factor is stenosis of AVM draining veins, as impairment of the AVM venous drainage system is associated with increased risk of intracranial hemorrhage. Currently, our understanding of the pathogenesis of AVM venous outflow stenosis is limited, as there is insufficient data on the blood flow patterns and local hemodynamic parameters of these draining veins. The angioarchitecture of AVMs features a nidus lacking a high resistance capillary network. Accordingly, our previous studies on AVM arterial feeders have demonstrated an abnormally high flow volume rate along with low pulsatility and resistance indices on quantitative magnetic resonance angiography. As such, AVM vessels endure high, non-physiologic levels of flow that may partially contribute to ectasia or stenosis depending on whether wall shear stress (WSS) is high or low, respectively. We hypothesize that AVM venous outflow stenosis occurs most commonly near the junction of the draining vein and the dural venous sinus. Increased flow volume rate through the AVM circuit coupled with the variation in compliance and rigidity between the walls of the draining vein and the dural venous sinus likely create turbulence of blood flow. The resulting flow separation, low WSS, and departure from axially aligned, unidirectional flow may create atherogenic conditions that can be implicated in venous intimal hyperplasia and outflow stenosis. We have previously found there to be a significant association between intimal hyperplasia risk factors and venous outflow stenosis. Additionally, we have found a significant association between age and likelihood as well as degree of stenosis, suggesting a progressive disease process. Similar conditions have been demonstrated in the pathophysiology of stenosis of the carotid artery and dialysis arteriovenous fistulas. In both of these conditions, the use of computational fluid dynamics (CFD) has been employed to characterize the local hemodynamic features that contribute to the pathogenesis of intimal hyperplasia and stenosis. We recommend the utilization of CFD to characterize the anatomic and hemodynamic features of AVM venous outflow stenosis. An improved understanding of the possible causative features of venous outflow stenosis may impact how clinicians choose to manage the treatment of patients with AVMs.