Experimental comparison of first-pass effect between direct thromboaspiration and combined thrombectomy in the setting of distal basilar occlusion.

BACKGROUND: Studies investigating endovascular therapy in vertebro-basilar stroke have led to controversial results in the past, but recent randomized trials seem to show an effectiveness superiority of endovascular therapy versus best medical treatment. However, uncertainty remains concerning many aspects of thrombectomy in acute basilar artery occlusion, notably technical considerations. This study compared the first-pass effect of direct thromboaspiration and combined thrombectomy in the setting of distal basilar occlusion. METHODS: An in-vitro experimental set-up was used, consisting of a vascular phantom model and thrombus analogs of different consistencies to mimic human clots. Thrombus analogs were injected into the model through the vertebral artery and flowed to the basilar distal third to mimic a distal basilar occlusion. Ten procedures were performed for each thrombus analog stiffness and technique (direct thromboaspiration versus combined thrombectomy). RESULTS: Direct thromboaspiration showed an overall first-pass effect rate of 83.3% (25/30) and was particularly effective for ultra-soft and soft clot analogs, but decreased for hard clot analogs. Combined thrombectomy had an overall first-pass effect rate of 56.7% (17/30). The effect rate for ultra-soft and soft clot analogs was 60% and 50% for hard clot analogs. In the softer clot analogs, the stent-retriever device used for the combined thrombectomies tended to deviate the clot analog from a co-axial trajectory with the aspiration catheter. CONCLUSIONS: In the context of distal basilar occlusion, our in-vitro results showed that higher first-pass effect rates were achieved with direct thromboaspiration compared to combined thrombectomy in all types of thrombus analogs.

Can micro-guidewire advancement forces predict clot consistency and location to assist the first-line technique for mechanical thrombectomy?

BACKGROUND: The identification of specific clot characteristics before mechanical thrombectomy (MTB) might allow the selection of the most effective first-line technique, thus potentially improving the procedural outcome. We aimed to evaluate if the microwire push forces could extrapolate information on clot consistency and extension before MTB, based on clot mechanical properties. METHODS: We measured in vitro the forces exerted on the proximal extremity of the guidewire during the advancement and retrieval of the guidewire through clot analogs of different compositions. In addition, we analyzed the forces exerted on the guidewire to extrapolate information about the location of the proximal and distal extremities of the clot analogs. RESULTS: The maximum forces recorded during the whole penetration phase were significantly different for hard and soft clots (median values, 55.6 mN vs 15.4 mN, respectively; P<0.0001). The maximum slope of the force curves recorded during the advancement of the guidewire for the first 3 s of penetration also significantly differentiated soft from hard clot analogs (7.6 mN/s vs 23.9 mN/s, respectively; P<0.0001). In addition, the qualitative analysis of the shape of the force curves obtained during the advancement and retrieval of the guidewire showed a good potential for the identification of the proximal and distal edges of the clot analogs. CONCLUSION: Our results demonstrated that it was possible to differentiate between soft and hard clot analogs. Furthermore, force measurements could give important information about the location of the clot extremities. Such an approach might support the selection of the first-line MTB technique, with the potential to improve the outcome.

Double Stent Retriever Technique for Mechanical Thrombectomy: A Systematic Review and Meta-Analysis.

BACKGROUND: Mechanical thrombectomy using a double stent retriever technique has recently been described for the treatment of acute ischemic stroke, but its efficacy and safety are not well-established. PURPOSE: The aim of this systematic review and meta-analysis was to evaluate reports of the use of a double stent retriever technique during the endovascular treatment of patients with ischemic stroke. DATA SOURCES: The PubMed, EMBASE, Web of Science, and Scopus databases were searched to identify all studies (clinical trials, cohort series, and case reports) investigating the utility of a double stent retriever technique for the treatment of stroke. The study is reported in accordance with PRISMA 2020 guidelines and was prospectively registered in PROSPERO (CRD42023482691). STUDY SELECTION: Seventeen studies involving a total of 128 patients with large-vessel occlusions predominantly in the anterior circulation (93.0%) were identified. DATA ANALYSIS: Outcomes of interest were the prevalence of successful recanalization (modified TICI ≥2b) and a first-pass effect following the double stent retriever technique as well as complications such as iatrogenic dissections and SAH. Data were pooled using a random effects model. DATA SYNTHESIS: The double stent retriever technique was used as a rescue strategy in occlusions refractory to conventional endovascular treatment in 68.7% (88/128) of patients and as a first-line strategy in 31.3% (40/128) of patients. The double stent retriever technique achieved an overall final modified TICI ≥2b in 92.6% cases, with a first-pass effect of 76.6%. The complication rate remained low, with 0.37% dissection and 1.56% SAH. LIMITATIONS: Limitations of the study include the following: 1) a large number of case reports or small series, 2) a meta-analysis of proportions with no statistical comparison with a control group, and 3) the lack of access to patient-level data. CONCLUSIONS: Our findings suggest that double stent retriever thrombectomy may be safe and associated with good recanalization outcomes, but prospective comparative studies are needed to determine which patients may benefit from this endovascular procedure.

Effectiveness of the preventive administration of vasoactive amines in counterbalancing significant patient blood pressure drops following nimodipine administration during mechanical thrombectomy procedures.

BACKGROUND: Focal vasospasm (FV) of the occluded vessel can occur during the endovascular treatment of acute ischemic stroke (AIS). Nimodipine is commonly used to treat vasospasm and can play a role in distinguishing it from artery narrowing due to iatrogenic dissection or residual clot. However, nimodipine administration can result in arterial hypotension and subsequent enlargement of the ischemic core. OBJECTIVE: To assess the efficacy of preventive and continuous vasoactive amine infusion to counterbalance nimodipine-induced hypotension. METHODS: We reviewed data from a prospective registry of patients treated for AIS between January 2019 and January 2022 who were administered nimodipine. All patients were equipped with an arterial cannula for invasive blood pressure measurement and given vasoactive amines preemptively before general anesthesia and throughout the procedure. Data obtained from invasive monitoring of mean arterial blood pressure (MABP) in a time-lapse of 25 min before and after nimodipine administration were analyzed. RESULTS: MABP significantly decreased after nimodipine administration but remained within the recommended range (81.79 ± 0.49 mmHg). Nimodipine was effective in reducing FV caused by stent retriever passage in 76.3% of cases. Furthermore, it proved valuable in diagnosing iatrogenic dissection (9.2%), residual clot (10.5%), or intracranial stenosis (4%). CONCLUSIONS: Infusion of vasoactive amines effectively counteracted the intraarterial nimodipine effect, thus avoiding frank arterial hypotension during endovascular treatment. Nimodipine has been useful in differentiating the diagnosis of FV resulting from mechanical thrombectomy and other potential causes, such as iatrogenic dissection or residual clot.

Benchtop evaluation of a double stent retriever thrombectomy technique for acute ischemic stroke treatment.

BACKGROUND AND PURPOSE: A mechanical thrombectomy technique using a double stent retriever approach has been reported for the treatment of patients with acute ischemic stroke. The purpose of this study was to perform a benchtop evaluation of the mechanism of action and efficacy of a double-stent retriever approach compared to a single-stent retriever approach. MATERIALS AND METHODS: In vitro, mechanical thrombectomy procedures were performed in a vascular phantom reproducing an M1-M2 occlusion with two different clot analog consistencies (soft and hard). We compared the double stent retriever approach to the single stent retriever approach and recorded the recanalization rate, distal embolization, and retrieval forces of each mechanical thrombectomy procedure. RESULTS: The double stent retriever approach achieved a higher recanalization rate and lower embolic complications compared to the single stent retriever approach. This seems to stem from two facts: the greater probability of targeting the correct artery with two stents in the case of bifurcation occlusion, and an improved clot capture mechanism using the double stent retriever approach. However, the double stent retriever was associated with an increased initial retrieval force. CONCLUSIONS: In vitro evaluation of the mechanism of action of the double stent retriever provided explanations that appear to support the high efficacy of such an approach in patient cohorts and could help operators when selecting the optimal mechanical thrombectomy strategy in cases of arterial occlusions difficult to treat with a single stent retriever.

Endovascular treatment strategies for simultaneous bilateral anterior circulation occlusions in acute ischemic stroke: A single-center experience and systematic review of the literature.

BACKGROUND: Bilateral and simultaneous occlusion of the anterior circulation is a rare event in patients with acute ischemic stroke. Although endovascular treatment is feasible and safe, the endovascular strategy to be used remains a subject of debate. OBJECTIVE: To assess the different endovascular strategies proposed for the treatment of a bilateral, simultaneous anterior circulation occlusion following acute ischemic stroke. METHODS: We present a retrospective study of the clinical and radiological records of all patients with a bilateral, simultaneous anterior circulation occlusion treated at our center between January 2019 and December 2022. Following the PRISMA guidelines, we also conducted a systematic review of the literature. RESULTS: Two patients with a bilateral and simultaneous middle cerebral artery occlusion were treated at our center during the study period. A TICI score ≥2b was obtained in 4 out of 4 occlusions. Modified Rankin Scale (mRS) at 90 days was 0 and 4, respectively. The literature review retrieved reports on 22 patients. The most frequent bilateral occlusion sites were internal carotid artery-middle cerebral artery. The clinical presentation was severe in most patients. A combined thrombectomy technique proved to have the highest number of first-pass recanalization. A TICI ≥2b was obtained in 95% of patients and an mRS ≤2 was found in 31.8% of patients. CONCLUSIONS: In patients with bilateral and simultaneous occlusion of the anterior circulation, endovascular treatment using a combined technique appears to be rapid and effective. The clinical evolution of this patient population strongly depends on the severity of the onset symptoms.

Three-dimensional rotational angiography improves mechanical thrombectomy recanalization rate for acute ischaemic stroke due to middle cerebral artery M2 segment occlusions.

BACKGROUND: Occlusions of the middle cerebral artery (MCA) M2 segments can be difficult to address with mechanical thrombectomy (MTB) using standard projections and this can affect the final recanalization. Three-dimensional rotational angiography (3D-RA) allows to obtain a 3D model of cerebral vessels in a few seconds and to determine the best two-dimensional (2D) projections to be selected to evaluate and treat cerebrovascular diseases, such as aneurysms or vascular malformations. We aimed to determine if 3D-RA could be applied also in MTB. METHODS: A retrospective review of two patient cohorts treated during two time periods of 12 months before and after the introduction of 3D-RA use at our institution for MTB in M2 occlusions. Analyses were conducted to compare the two groups for procedural characteristics, such as timing, recanalization rate and complications and clinical outcome. RESULTS: One hundred acute ischaemic stroke (AIS) patients (3D-RA group = 57; controls = 43) underwent MTB for an M2 occlusion during the two study periods. Recanalization rates were significantly higher in cases treated with 3D-RA. The mean 3D technique thrombectomy time was compared to that of non-3D cases (47 vs. 49 min, respectively). CONCLUSIONS: Our findings showed that 3D-RA is a useful tool to select specific working projections to AIS patients presenting an M2 occlusion by improving final recanalization compared to standard projections, without increasing the overall procedural time.

In vitro evaluation of how the presence of the stent retriever and microcatheter influences aspiration parameters in thrombectomy according to their position inside the aspiration catheter.

BACKGROUND: Several variations of the combined thrombectomy technique for acute ischemic stroke using a stent retriever and aspiration catheter have been described. The aim of our study was to assess how the presence of the microcatheter and stent retriever affect the basic aspiration parameters, namely, flow rate and aspiration force, depending on their position within the aspiration catheter. METHODS: Two experimental set-ups were designed to assess changes in flow rate and aspiration force according to the position of the stent retriever and microcatheter within the aspiration catheter. RESULTS: The transition of the stent retriever and microcatheter from the distal to proximal position resulted in a progressive increase in the flow rate, but with no impact on aspiration force. Additionally, the size of the stent retriever had no significant effect on flow rate changes and the reduction in flow rate was related to the microcatheter diameter. Negative pressure generated inside the aspiration catheter impacted on its distal segment located beyond the radiopaque marker, thus leading to its partial collapse. As a consequence, the measured aspiration force was lower than the theoretical aspiration force level for all tested aspiration catheters. CONCLUSIONS: In our experimental model, the position of the stent retriever and microcatheter within the aspirator catheter affected the flow rate, but not the aspiration force. Negative pressure generated within the aspiration catheter appeared to determine a partial collapse of the distal segment that resulted in a less effective aspiration force than the theoretical aspiration force level.

A high resolution scanning electron microscopy analysis of intracranial thrombi embedded along the stent retrievers.

Endovascular treatment with stent retriever thrombectomy is a major advancement in the standard of care in acute ischemic stroke (AIS). The modalities through which thrombi embed along stent retriever following mechanical thrombectomy (MTB) have not yet been elucidated. Using scanning electron microscopy (SEM), we analyzed the appearance of thrombi retrieved by MTB from AIS patients, when embedded into the stent retriever. We observed that the organization and structural compactness vary for compositionally different thrombi. The modalities of attachment onto the stent vary according to thrombus composition and organization.

Multimodality Characterization of the Clot in Acute Stroke.

Aim: Current treatment of occluded cerebral vessels can be done by a variety of endovascular techniques. Sometimes, the clot responds in varying degrees to the treatment chosen. The Ex vivo characterization of the clot occluding the arteries in acute ischemic stroke can help in understanding the underlying imaging features obtained from pre-treatment brain scans. For this reason, we explored the potential of microCT when combined with electron microscopy for clot characterization. Results were compared to the clinical CT findings. Methods: 16 patients (9 males, 8 females, age range 54-93 years) who were referred to our institution for acute stroke underwent dual-source CT. Results: Clinical CT clots were seen as either iso or hyperdense. This was corroborated with micro-CT, and electron microscopy can show the detailed composition. Conclusion: MicroCT values can be used as an indicator for red blood cells-rich composition of clots. Meaningful information regarding the clot composition and modalities of embedding along the stent retrievers can be obtained through a combination of microCT and electron microscopy.

Acute Stenting and Concomitant Tirofiban Administration for the Endovascular Treatment of Acute Ischemic Stroke Related to Intracranial Artery Dissections: A Single Center Experience and Systematic Review of the Literature.

BACKGROUND: Intracranial artery dissection is an uncommon cause of acute ischemic stroke. Although acute stenting of the dissected arterial segment is a therapeutic option, the associated antiplatelet regimen remains a matter of debate. OBJECTIVES: To evaluate the efficacy and safety of acute intracranial stenting together with concomitant intravenous administration of tirofiban and to perform a systematic review of the literature. MATERIALS AND METHODS: A single-center, retrospective study of the clinical and radiological records of all patients treated at our center by intracranial stenting in the setting of acute ischemic stroke between January 2010 and December 2020. A systematic review of the literature was conducted according to the PRISMA-P guidelines for relevant publications from January 1976 to December 2020 on intracranial artery dissection treated by stent. RESULTS: Seven patients with intracranial artery dissections underwent acute stenting with concomitant tirofiban during the study period. Mid-term follow-up showed parent artery patency in 6/7 cases (85.7%). The modified Rankin Score was ≤ 0-2 at 3 months in 5/7 cases (71.4%). The literature review identified 22 patients with intracranial artery dissection treated with acute stenting in association with different antithrombotic therapies. Complete revascularization was obtained in 86.3% of cases with a modified Rankin Score of ≤ 0-2 in 68% of patients at 3-month follow-up. CONCLUSIONS: Acute intracranial stenting together with intravenous tirofiban administration could be a therapeutic option in patients with intracranial artery dissection and a small ischemic core.

Experimental evaluation of direct thromboaspiration efficacy according to the angle of interaction between the aspiration catheter and the clot.

BACKGROUND: Successful direct thromboaspiration (DTA) is related to several factors such as clot consistency, size, and location. It has also been demonstrated recently that the angle of interaction (AOI) formed by the aspiration catheter and the clot is related to DTA efficacy. The aims of this study were three-fold: (a) to confirm the clinical finding that the AOI formed by the aspiration catheter and the clot influence DTA efficacy; (b) to evaluate to what extent this influence varies according to differences in clot consistency and size; and (c) to validate stent retriever thrombectomy as an effective rescue treatment after DTA failure in the presence of an unfavorable AOI. METHODS: A rigid vascular phantom designed to reproduce a middle cerebral artery trifurcation anatomy with three M2 segments forming different angles with M1 and thrombus analog of different consistencies and sizes was used. RESULTS: DTA was highly effective for AOIs >125.5°, irrespective of thrombus analog features. However, its efficacy decreased for acute AOIs. Rescue stent retriever thrombectomy was effective in 92.6% of cases of DTA failure. CONCLUSIONS: This in vitro study confirmed that the AOI formed by the aspiration catheter and the thrombus analog influenced DTA efficacy, with an AOI >125.5° related to an effective DTA. Stent retriever thrombectomy was an effective rescue treatment after DTA failure, even in the presence of an unfavorable AOI.

Clot-Based Radiomics Predict a Mechanical Thrombectomy Strategy for Successful Recanalization in Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Mechanical thrombectomy (MTB) is a reference treatment for acute ischemic stroke, with several endovascular strategies currently available. However, no quantitative methods are available for the selection of the best endovascular strategy or to predict the difficulty of clot removal. We aimed to investigate the predictive value of an endovascular strategy based on radiomic features extracted from the clot on preinterventional, noncontrast computed tomography to identify patients with first-attempt recanalization with thromboaspiration and to predict the overall number of passages needed with an MTB device for successful recanalization. METHODS: We performed a study including 2 cohorts of patients admitted to our hospital: a retrospective training cohort (n=109) and a prospective validation cohort (n=47). Thrombi were segmented on noncontrast computed tomography, followed by the automatic computation of 1485 thrombus-related radiomic features. After selection of the relevant features, 2 machine learning models were developed on the training cohort to predict (1) first-attempt recanalization with thromboaspiration and (2) the overall number of passages with MTB devices for successful recanalization. The performance of the models was evaluated on the prospective validation cohort. RESULTS: A small subset of radiomic features (n=9) was predictive of first-attempt recanalization with thromboaspiration (receiver operating characteristic curve-area under the curve, 0.88). The same subset also predicted the overall number of passages required for successful recanalization (explained variance, 0.70; mean squared error, 0.76; Pearson correlation coefficient, 0.73; P<0.05). CONCLUSIONS: Clot-based radiomics have the ability to predict an MTB strategy for successful recanalization in acute ischemic stroke, thus allowing a potentially better selection of the MTB strategy, as well as patients who are most likely to benefit from the intervention.

Thoracic aggressive vertebral hemangiomas: multidisciplinary management in a hybrid room.

PURPOSE: Vertebral hemangiomas (VH) account for 2-3% of all spinal tumors. The majority is incidentally found on radiographic studies: 1% present with pain and/or neurologic deficits. We report our experience with the multidisciplinary management of aggressive symptomatic thoracic VH by concomitant intraoperative sclerotization with sodium tetradecyl sulfate (STS), vertebroplasty, posterior decompression (with/without fusion) and surgical resection in a hybrid operating room (HR) equipped with a rotational scanner and a radiolucent operating table. METHODS: Patients admitted with aggressive spinal VH between 2007 and 2018 were included. Data regarding demographics, presenting symptoms, location of the lesion, preoperative embolization, length of the surgery, estimated blood loss (EBL) as well as follow-up (FU) were retrieved. RESULTS: Five patients were included (three females, mean age 65 years; range 59-75). Three patients presented with a myelopathy and two mechanical thoracic pain. All patients underwent a single-stage percutaneous sclerotization and vertebroplasty followed by a surgical decompression associated with epidural intralesional injection of STS and subtotal resection of the epidural lesion. Two patients had preoperative embolization. Mean procedural duration was 338 min (range 210-480 min). Four patients had marginal EBL, one patient had 500 ml EBL. Patients had no evidence of lesion recurrence or progression at the end of the follow-up. CONCLUSIONS: The single-stage multimodal management of aggressive symptomatic VH is safe and effective. It allows for a direct intraoperative sclerotherapy combined with maximal tumor resection, resulting in reduced blood loss. The use of STS as a direct intraoperative sclerotizing agent is safe and reliable.

Dual Pathologies: Pial Arteriovenous Fistula in Combination with an Arteriovenous Malformation.

BACKGROUND: A pial arteriovenous fistula (PAVF) is a rare neurovascular pathology consisting of a direct connection between one or more arterial feeders and a single venous channel. A PAVF was previously considered a subtype of an arteriovenous malformation (AVM). In the current literature these are distinguished as two independent entities with different clinical, physiopathologic, and structural characteristics. We report a case of a surgically treated 37-year-old woman with an extremely rare combination of an unruptured PAVF and AVM. PATIENT: The AVM was mainly supplied by feeders of the middle cerebral artery and drained into the sigmoid sinus via an abnormally dilated and tortuous vein. Following its resection, intraoperative digital subtraction angiography (DSA) in the hybrid operating room revealed the presence of a PAVF that had not been noted during the preoperative planning. Hence the PAVF was completely disconnected as confirmed by DSA again. CONCLUSION: This is the second reported case of an AVM-associated PAVF. Without the intraoperative DSA in the hybrid operating room, this unusual complex cerebrovascular entity would likely have been missed.

Direct thromboaspiration efficacy for mechanical thrombectomy is related to the angle of interaction between the aspiration catheter and the clot.

BACKGROUND: Direct thromboaspiration has been reported as an effective mechanical treatment for acute ischemic stroke. We aimed to determine whether the angle of interaction between the aspiration catheter and the clot affects the success of clot removal in ischemic stroke patients with large vessel occlusion in the anterior and posterior circulation. METHODS: All patients treated at our institution by direct thromboaspiration as a firstline technique between January 2016 and December 2017 were enrolled in the study. We retrospectively reviewed baseline and procedural characteristics, the angle of interaction formed between the aspiration catheter and the clot, the modified Thrombolysis in Cerebral Infarction score, and the 3 month modified Rankin Scale score. RESULTS: 85 patients underwent direct thromboaspiration as the firstline treatment during the study period. 100 direct thromboaspiration passes were performed. An angle of interaction of ≥125.5° significantly influenced the success of clot removal (P<0.001) with good sensitivity and specificity, in particular for occlusion of the middle cerebral and basilar artery. The combination of aspiration with a stent retriever based thrombectomy was a valid rescue treatment in cases of standalone direct thromboaspiration failure. CONCLUSIONS: In our series, an angle of interaction between the aspiration catheter and the clot of ≥125.5° was significantly associated with successful clot removal. The prediction of the angle of interaction on pretreatment imaging may help operators to select the most adequate mechanical thrombectomy technique on a case by case basis.

Posterior Fossa Arteriovenous Malformations: Experience with 14 Patients and a Systematic Review of the Literature.

BACKGROUND: The optimal management of posterior fossa arteriovenous malformations (pfAVMs) is a matter of debate. To advance this discussion, we present our clinical series and the results of a systematic literature review according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. METHODS: Fourteen consecutive patients with pfAVMs were admitted between 2007 and 2018. Preoperative status, radiologic parameters, and outcome were assessed. A systematic literature review was performed according to the PRISMA-P guidelines. RESULTS: Ten patients presented with rupture (71%), of whom three had associated aneurysms (AAs). The treatments were microsurgery (n = 4), endovascular (n = 3), radiosurgery (n = 2), a combination of two or three treatment modalities (n = 3), or conservative (n = 2). At discharge, all four patients (100%) with unruptured pfAVMs had a good outcome (modified Rankin Scale [mRS]: 0-2). In contrast, in ruptured pfAVM cases, mRS was 0 to 2 in four patients (40%), mRS 3 to 4 in two (20%), mRS 5 in three (30%), and one patient (10%) died within 30 days after gamma knife treatment due to pancreatitis secondary to chronic alcohol abuse. At discharge, four patients (29%) had persistent preinterventional cranial nerve and/or focal neurologic deficits. The literature review identified 63 articles with 1,753 pfAVM patients. Overall, 66% of pfAVMs presented with rupture, and AAs were found in 20% of the cases, which is higher than in supratentorial AVMs (stAVMs). CONCLUSIONS: Because pfAVMs are associated with higher rates of hemorrhagic presentation, higher rates of morbidity and mortality when ruptured, and have a higher incidence of AAs compared with stAVMs, early curative treatment is recommended as soon as the diagnosis is established, regardless of rupture status.

Experimental evaluation of the NeVa™ thrombectomy device a novel stent retriever conceived to improve efficacy of organized clot removal.

BACKGROUND AND PURPOSE: Stent retrievers are recognized as the most effective devices for intracranial thrombectomy. Although highly effective, such devices fail in clot removal when the brain vessel occlusion is due to organized, firm clots. The mechanism of failure is that during the retrieval, devices remain compressed by the organized clot and slide between it and the vessel wall without any removal effect. The aim of the current study is to present the preclinical evaluation of the Neva™ device, a novel stent retriever designed to improve the incorporation and removal of organized thrombi. MATERIALS AND METHODS: Preclinical evaluation of the Neva™ device was divided in three main chapters: efficacy analysis, mechanical analysis and safety analysis. Efficacy and mechanical analysis aimed to investigate the behavior during the retrieval of the Neva™ device and its interaction with experimental organized clots. Safety analysis was conducted on animals in order to investigate the effect of the Neva™ device on real arteries after simulated thrombectomy maneuvers. RESULTS: Neva™ device showed a high rate of "optimal clot integration" and "effective clot removal" which was related to constant cohesion to the vessel wall during retrievals. Safety analysis showed as the most frequent finding the disruption of the intima of the tested vessels with, in some cases, minimal disruption of the internal elastic lamina. CONCLUSIONS: The Neva™ device has demonstrated safety and efficacy in a pre-clinical study. Such encouraging, preliminary results have to be compared with those of clinical trials.

MRI patient selection for endovascular thrombectomy in acute ischemic stroke: correlation between pretreatment diffusion weighted imaging and outcome scores.

INTRODUCTION: Eligibility for endovascular treatment (EVT) in patients with acute ischemic stroke (AIS) depends, amongst other factors, on CT- or MR-based scores. The aim of this study was to investigate the role of Alberta Stroke Program Early CT score based on diffusion weighted imaging (MR-ASPECT) in the assessment of brain damage pre-EVT, patient selection for EVT and outcome. MATERIALS AND METHODS: We included in this study patients with National Institute of Health stroke score (NIHSS) at admission ≥ 8, MR-ASPECT ≥ 5 and anterior AIS, who were treated with EVT in our hospital. All patients were clinically evaluated at admission, post-EVT, discharge and at 3-month follow-up. We used MR-ASPECT to establish infarct core extension at admission. We evaluated ASPECT score at admission (CT-ASPECT-IN), 24 h after EVT and at discharge, NIHSS, modified Ranking Scale (mRS), Thrombolysis in Cerebral Infarction scale (TICI), onset-to-intervention-delay (OTID) and Collateral Circulation Score (CCS). RESULTS: 68 patients (mean age 78 ± 11.9 years) were included in this study. 54.4 and 64.7% of patients had strong clinical improvement after 24 h from EVT and at discharge, respectively. NIHSS evaluated 24 h after EVT correlated with CCS, TICI and OTID. We observed a favourable outcome (mRS 0-2) in 52.9% of patients at 3-month follow-up. MR-ASPECT score correlated with post-EVT outcome better than CT-ASPECT-IN scores. CONCLUSION: MR-ASPECT score based on diffusion weighted imaging is useful for the selection of patients with AIS that can have a favourable outcome from EVT. A prompt EVT has huge impact on patient outcome.

The Catch Mini stent retriever for mechanical thrombectomy in distal intracranial occlusions.

OBJECTIVE: Mechanical thrombectomy (MTB) is a treatment of reference for acute ischemic stroke due to large brain vessel occlusion but some concerns remain about its use in small distal branches. In the present study, we assessed the efficacy and the safety of distal MTB using the Catch Mini (CM) stent retriever. METHODS: We retrospectively reviewed a prospectively maintained database of all consecutive patients who underwent MTB for a distal intracranial occlusion with the Catch Mini device at our hospital. RESULTS: Forty-one patient underwent MTB for distal intracranial occlusions using the CM stent retriever. Good capillary reperfusion (TICT≥2b) was observed in 32 out of 41 patients (78%). Focal ischemia within the territory vascularized by the artery addressed by the CM was observed in 8 patients (19.5%). Post-procedural vasospasm was observed in 8 patients, all responding rapidly to vasodilatator administration. Two asymptomatic hemorrhages (4.9%) were noted on follow-up imaging (one patechial hemorrhage and one parenchymal hematoma) in patients with M2 occlusions. No vessel rupture were observed. Overall, good neurological outcome at three months (mRS≤2) was observed in 28 (out of 34 patients followed; 82.4%) of patients. CONCLUSIONS: Our single-center experience shows that the CM stent retriever is safe and effective for the recanalization of small diameter distal branches feeding eloquent brain areas.