Proximal M1 Segment Research Articles

Abstract 064: The Pushability of Commonly Used Microwires in Neuroendovascular Procedures

Introduction In distal and medium‐vessel occlusions (DMVOs), there are increasing opportunities to deliver devices through tortuous and medium sized arteries. However, this comes at the risk of microwire perforation during distal microcatheter advancement for navigation in these curved, slender vessels, leading to hemorrhagic complications. Currently, microwires with a range of stiffness levels are available. However, it is unclear how the variations in stiffness and the relative positioning of the microwire and microcatheter may affect the force applied to the vessel wall. Few studies have compared objective metrics across different commonly used devices. We sought to compare the pushability of various Synchro Select and Chikai microwires using both proximal and distal support. Methods In a moderate tortuosity, silicone flow model of the middle cerebral artery (MCA) branches, we tested 0.014” nitinol microwires (Synchro Select Soft, Standard, or Support), or 0.014” stainless steel microwires (Chikai, Black, and Black Soft) in a TrevoTrak 21 microcatheter docked either in the proximal M1 segment or distal M2 segment. Applied force was measured using an Imada force gauge DST‐1A at the M2 ten times for each experiment. The slope, measured in mN per mm, of the applied distal force during the maximal pushing period was calculated. Results The average slope of the pushing force within a distal microcatheter was 10.64 mN/mm with a Synchro Soft, 10.85 mN/mm with a Standard, and 15.28 mN/mm with a Support microwire (p < 0.0001). The average slope of the pushing force in a proximal microcatheter was 1.61 mN/mm with a Synchro Soft, 3.15 mN with a Synchro Standard, and 3.87 mN with a Synchro Support microwire (p <0.001). With the Chikai microwires, the average slope of the pushing force within a distal microcatheter was 12.48 mN/mm with a Chikai Black Soft wire, 12.82 mN/mm with a Chikai Black microwire, and 14.11 mN/mm using a Chikai microwire (p=0.801). Within a proximal microcatheter, the average maximal force was 2.42 mN/mm using a Chikai Black Soft wire, 3.16 mN/mm using Chikai Black, and 3.91 mN/mm using the Chikai wire (p < 0.001). Conclusion This study demonstrated that stiffer microwires push the arterial wall with significantly greater force within a microcatheter close to the wall. Pushability of the microwire significantly dropped across all microwires when the microcatheter was positioned more proximally. This is the first known report of the pushability of commonly used microsystems in neuroendovascular procedures.

Abstract 198: Case Report: Thrombectomy using Zoom Reperfusion System In Pediatric Acute Ischemic Strokes

Introduction Zoom reperfusion system (Imperative Care, CA) has proven to be promising for use in mechanical thrombectomies in adults but has not been described in pediatrics to our knowledge. We present two cases of a 14‐year‐old boy with acute right middle cerebral artery (MCA) syndrome and a 10‐year‐old boy with acute left MCA syndrome who underwent mechanical thrombectomy using Zoom Reperfusion System safely with TICI 2B and 3 recanalization respectively. Methods Case report and review of literature Results Case 1: 14‐year‐old previously healthy boy presented to our facility for acute right MCA syndrome secondary to right supraclinoid internal carotid artery (ICA) occlusion. After receiving alteplase, patient was taken for mechanical thrombectomy. After femoral access was obtained, an 8‐French sheath was introduced into the right femoral artery through which a Zoom 88 catheter and 5‐French BERN catheter (Terumo) were coaxially advanced over a Terumo Glidewire into the right common carotid artery. Under roadmap guidance, the Zoom 88 catheter was parked at the lacerum ICA segment with BERN catheter and Glidewire then removed. Angiogram demonstrated complete occlusion of the ICA just past the origin of the ophthalmic artery. Via Zoom 88 catheter, a Zoom 71 catheter was then navigated to the face of clot over a velocity microcatheter (Penumbra) and synchro 2 wire system (Stryker) which was then removed. The vacuum manifold was then attached to Zoom 71 catheter and allowed to engage with the clot for 3 minutes prior to withdrawal into the Zoom 88 catheter. TICI 2B recanalization was achieved with sub‐occlusive thrombus within the proximal M1 segment. Retrieval of the sub‐occlusive thrombus in the M1 segment was performed with TREVO stentriever (Stryker). Procedure was complicated by vasospasm in the A1 and M2 segments which resolved with milrinone and verapamil infused through the Zoom 88 catheter. Case 2: 10‐year‐old with left hypoplastic heart syndrome presented to our facility for acute left MCA syndrome due to left ICA terminus occlusion. Mechanical thrombectomy was performed after receiving alteplase. Femoral artery access was obtained with a 8‐French sheath, through which Zoom 88 catheter and 5‐French select catheter (Penumbra) were advanced over Terumo Glidewire into the left common carotid artery. Under roadmap guidance, the Zoom 88 catheter was parked at the ophthalmic segment of ICA with select catheter and Glidewire then removed. Angiogram demonstrated complete occlusion at the ICA terminus. Zoom 71 catheter was introduced through Zoom 88 catheter and navigated to the face of clot at the ICA terminus over velocity microcatheter (Penumbra) and synchro wire system (Stryker) which was then removed. Zoom 71 was then attached to a vacuum manifold to engage with the clot for 90 seconds. TICI 2A recanalization after first pass was achieved with flow restoration in anterior cerebral artery but none in the MCA.TICI 3 recanalization was achieved after second pass. Conclusion The use of Zoom reperfusion system potentially proves to be safe for use in the pediatric age group with good recanalization results and no intraoperative or postoperative complications.

Risk of acute stroke in young patients with new-onset lupus nephritis: a case series (P9-5.028)

<h3>Objective:</h3> To investigate the relationship between new-onset lupus nephritis and acute stroke. <h3>Background:</h3> Systemic lupus erythematosus (SLE) is a multi-organ autoimmune disease associated with an increased risk for stroke. <h3>Design/Methods:</h3> We reviewed medical records of patients evaluated by the inpatient Stanford Stroke Service from 2020–2022 with confirmed stroke on neuroimaging and diagnosis of SLE based on American College of Rheumatology Classification Criteria. Data regarding the clinical course, laboratory testing, and neuroimaging were extracted from electronic medical records. <h3>Results:</h3> Three patients were identified (two male, one female) with ages ranging from 17–32 years. Two patents had prior diagnosis of SLE without renal involvement. Magnetic resonance imaging obtained for all three patients demonstrated ischemic strokes restricted to a vascular territory. Magnetic resonance angiography demonstrated a proximal left superior cerebellar artery thrombus for one patient and slight enhancement in the proximal left M1-segment for another patient. Initial preliminary labs for all three patients were notable for leukopenia, anemia, hematuria, proteinuria, elevated urine protein/creatine ratio. Serologic testing was notable for positive ANA, positive anti-dsDNA, positive anti-Sm, low C3, and low C4. Anti-phospholipid labs and hypercoagulable work-up was negative. CSF analysis yielded normal protein, glucose, WBC, and RBC. All three patients were diagnosed with new-onset lupus nephritis, with two patients undergoing confirmatory renal biopsy. Patients were initially treated with a combination of prednisone, mycophenolate mofetil, and/or hydroxychloroquine and closely followed as an outpatient. One patient with vessel enhancement on initial imaging continued to have reoccurring strokes and required escalation of immunotherapy to cyclophosphamide with eventual remission and normalization of antibody levels. <h3>Conclusions:</h3> This case series presents several young patients with acute stroke in the setting of new-onset lupus nephritis without other traditional SLE-related stroke risk factors. Further research is needed to guide the stratification of stroke risk among patients with SLE. <b>Disclosure:</b> Dr. Wu has nothing to disclose. Dr. Han has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Roche. Dr. Han has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Arena Pharmaceuticals. Dr. Lee has nothing to disclose.

Abstract Number ‐ 266: Focal Cerebral CNS Vasculitis due to SARS‐CoV‐2 Infection

Introduction Several neurological manifestations of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection, including anosmia, encephalopathy, and stroke, have been reported. We report a case of a 42‐year‐old man presenting with ischemic stroke due to cerebral vasculitis in the setting of SARS‐CoV‐2 infection. Methods Case report Results A 42‐year‐old man, recently diagnosed with SARS‐CoV‐2 infection, presented with nonfluent aphasia and right‐sided hemiparesis that started five hours prior. Neurological examination revealed nonfluent aphasia, right‐sided facial palsy, and hemiparesis. Computed tomography (CT) of the head showed left‐sided caudate infarct and early ischemic changes in the left putamen. CT angiography (CTA) revealed occlusion of the proximal left M1 segment. Patient’s symptoms rapidly improved and mechanical thrombectomy was not pursued. Patient was started on dual antiplatelet therapy with aspirin and clopidogrel. Magnetic resonance imaging (MRI) of the brain showed acute infarcts in the left posterior parietal, lentiform nucleus, and frontal cortex. CT of the chest revealed bilateral subsegmental pulmonary emboli. Patient was discharged on apixaban and atorvastatin daily, with mild residual aphasia. A month later, the patient returned with dysarthria and right‐sided paresthesia that began three hours prior. CTA showed severe left proximal M1 stenosis involving a longer segment. He was started on vasopressor. Symptoms resolved within 24 hours with residual mild aphasia. MRI brain revealed multiple foci of cortical infarcts within the left MCA territory with no diffusion/ perfusion mismatch. MRA head showed further pruning of the distal MCA branches within the left sylvian fissure with severe stenosis along the mid‐M1 and minimal flow anteriorly, with contrast enhancement at the site of the stenosis, suggestive of vasculitis. Autoimmune vasculitis panel was unremarkable. Due to suspicion of focal inflammatory vasculopathy related to recent SARS‐CoV‐2 infection, patient was started on intravenous methylprednisolone 1 gram daily for 5 days followed by a prednisone taper. MRA revealed improved blood flow in the left middle cerebral artery and branches. The was discharged on apixaban, aspirin, atorvastatin, and a prednisone taper with mild residual aphasia. Conclusions To our knowledge, this is the first reported case of CNS vasculitis associated with an underlying SARS‐CoV‐2 infection with radiographic improvement of blood flow in the affected vessel within 4 days of treatment with high‐dose steroids. This case supports the use of high‐dose steroids in patients with CNS vasculitis associated with SARS‐CoV‐2 to prevent further stroke burden.

HR-MRI findings of intracranial artery stenosis and distribution of atherosclerotic plaques caused by different etiologies.

To investigate the etiology of intracranial artery stenosis and the distribution characteristics of intracranial artery atherosclerotic stenosis using high-resolution magnetic resonance imaging (HR-MRI). A total of 262 patients with intracranial artery stenosis that underwent HR-MRI from November 2019 to December 2020 were retrospectively enrolled. The etiology of intracranial anterior and posterior circulation artery stenosis was analyzed, and the relationship between the location of plaques and the distribution characteristics of plaques and the occurrence of ischemic stroke was summarized. A total of 276 plaques were identified with HR-MRI. There were 101 cases (36.59%) in the middle cerebral artery (MCA), 14 cases (5.07%) in the posterior cerebral artery (PCA), 90 cases (32.62%) in vertebral artery (VA), and 71 cases (25.72%) in the basilar artery (BA). The infarct rate of ventral and superior wall MCA plaques was higher than that of dorsal and inferior wall (63.33% vs 31.25% P = 0.021) (100.00% vs 50% P = 0.022). MCA with plaques throughout the course had the greatest degree of stenosis (P < 0.001). Sphenoid segment (M1) of MCA was most susceptible (85 cases, 84.16%), MCA plaques were most common in the proximal M1 segment (35 cases, 34.65%), and most BA plaques were found in the distal segment (28 cases, 39.44%). PCA plaques were most frequently involved in traffic anterior segment (P1) (7 cases, 50.00%). HR-MRI could provide accurate imaging reference for clinical evaluation of intracranial arterial stenosis and formulation of treatment plans. The intracranial arterial plates mostly appeared in the middle cerebral artery and vertebral artery. Middle cerebral arteries with atherosclerotic plaques are more likely to narrow.

Abstract WP160: First-Pass Effect Modification In Proximal Vs Distal M1 Occlusion Thrombectomy

Modified first pass effect (mFPE) of TICI 2B or greater is an independent predictor of clinical outcome in patients who undergo mechanical thrombectomy (MT). Location of the occlusion in the M1 segment may affect the mFPE and may influence clinical outcomes. A comparison of mFPE between occlusions of the proximal and distal (sparing lenticulostriate branches) M1 segments of the MCA has yet to be performed. We aim to examine the interaction between first pass effect and clinical outcomes in proximal versus distal M1 occlusions. We performed retrospective analysis of patients who underwent MT between 2014 and 2020. Patients were included if they were treated for M1 occlusion within 24 hours from last seen normal, and achieved successful recanalization (TICI2b or greater). Patients were excluded if they were not successfully recanalized, or if they had other intracranial or multifocal occlusions. A total of 264 patients were included in this analysis. Ninety two patients had proximal M1 occlusions and 172 had distal M1 occlusions. Patients with proximal M1 occlusions had higher NIHSS (median 18 vs. 16, p=0.003), lower ASPECTS (mean 8.5 vs 9, p=0.02), and were less likely to be females (44.6% vs. 62.8%, p=0.006). Modified first pass effect was achieved in 45.3% of distal M1 occlusions compared to 31.9% of proximal (p=0.047). Excellent clinical outcome, defined as mRS of 0-1 at 90 days was higher in distal occlusion group (38.8% vs. 24.7%, p=0.03). Additionally, the proximal occlusion group was more likely to experience any grade of hemorrhagic transformation (HT) (37.4 vs. 23.3, p=0.02). Other baseline characteristics and time metrics did not differ between the two groups. In a multivariate analysis of predictors of excellent outcome in the overall cohort, ASPECTS (OR=1.39, p = 0.026) and proximal occlusion site (OR=0.485, p=0.037) were the only two independent predictors. Therefore, mFPE was not a predictor of excellent outcome when adjusted for exact location of occlusion.

Abstract 1122‐000171: Unusual Multicompartmental Intracranial Hemorrhage After Tenecteplase Administration

Introduction : The 2019 AHA/ASA updated Guidelines for the Early Management of Patients with Acute Ischemic Stroke mention tenecteplase (TNK) as a reasonable therapy in patients without contraindications for IV fibrinolysis who are also eligible to undergo mechanical thrombectomy. We describe a case of acute left MCA ischemic stroke treated with IV TNK (IV bolus of 0.25 mg/kg) followed by mechanical thrombectomy with subsequent multicompartmental intracranial hemorrhages unrelated to area of infraction. Methods : A retrospective review at a single center university hospital was performed for all intravenous TNK administrations outside of a clinical trial setting from October 2020 to July 2021. Results : A 61‐year‐old male with history of HTN and cardiomyopathy (EF&lt;20%). Presented with sudden onset right sided weakness, aphasia and left gaze. Presenting NIHSS was 28. CT head with hyperdense left MCA sign and ASPECTS score of 10. CTA confirmed proximal left MCA M1 segment occlusion. IV TNK was given within 01:23 hours of symptoms onset. Subsequently, patient underwent emergent mechanical thrombectomy for disabling large vessel occlusion stroke. Spontaneous near complete recanalization of left MCA occlusion was noted on initial angiography run with small non flow limiting distal thrombi visualized in the distal MCA territories. Immediate post procedure CT head was negative for any intracranial hemorrhage. Patient’s exam was noted to improve to NIHSS of 2. Approximately 6 hours after the TNK administration, patient became acutely unresponsive with NIHSS of 26. With Glasgow Coma Scale 7 patient required emergent intubation. CT head revealed bilateral cerebellar intraparenchymal hemorrhages, extensive subarachnoid hemorrhage in basal cisterns and within the sulci in bilateral frontotemporal regions, as well as subdural hemorrhages along the falx and tentorial dural folds. Hypertonic saline was administered followed by emergent extraventricular drain placement. Tranexamic acid 1000 mg was given as emergent reversal, fibrinogen level was 155 mg/dL. Despite aggressive medical management and over following 24 hours, exam worsened with loss of pupillary reflexes. Patient was terminally extubated 2 days after initial presentation in accordance with his advance directives. Conclusions : Tenecteplase was a reasonable choice in this case given LVO and disabling stroke. The patient’s neurological exam improved significantly after TNK with evidence of spontaneous recanalization. However, patient’s multicompartmental intracranial hemorrhages unrelated to area of infraction were unusual in the absence of any vascular lesions to predispose hemorrhage based on CT and conventional angiography. Further observational studies are warranted to evaluate similar complications of Tenecteplase administration and their occurrence rates.

Treatment of a Giant Thrombotic M1 Segment Middle Cerebral Artery Aneurysm With Radial Artery Bypass and Distal Occlusion to Create a "Blind Sac" Following Endovascular Failure: 2-Dimensional Operative Video.

The case is of a 36-yr-old male with a previously coiled aneurysm arising from the proximal M1 segment of the middle cerebral artery (MCA) just beyond the internal carotid artery (ICA) bifurcation who presented to our institution with subjective left hemiparesis, headache, and vomiting. Physical exam revealed a left facial droop, but neurological exam was otherwise normal, including full motor strength. Neuroimaging showed a large partially thrombosed aneurysm recurrence, measuring 5.2 cm, with obstructive hydrocephalus. Cerebral angiogram showed filling within a small portion of the aneurysm and marked stenosis of the MCA beyond the neck. A ventriculostomy was placed, and he underwent a pterional craniotomy for high-flow radial artery bypass from the common carotid artery to an M2 branch of the MCA and clip placement. This case demonstrates the creation of a blind sac by placing a clip on the MCA distal to the aneurysm and proximal to the lenticulostriate arteries for the treatment of a giant proximal M1 segment aneurysm. Postoperative digital subtraction angiography shows the MCA distribution, including the lenticulostriate arteries, filling through the radial artery bypass, and anterograde flow through the ICA, which perfuses up to and including the anterior choroidal artery. There is no residual filling of the aneurysm. The patient remained at his neurological baseline postoperatively and required ventriculoperitoneal shunt placement for hydrocephalus. At outpatient follow-up, computed tomography imaging showed decreased size of the thrombosed aneurysm, measuring 4.5 cm, and he had no neurological deficits. The patient gave informed consent for surgery and deidentified video recording of this case.

Abstract P574: Anatomic Distribution of High-Resolution Vessel Wall Imaging Findings in a Cohort of Patients With Moyamoya Disease Evaluated at a Midwest American Institution

Introduction: High-resolution vessel wall imaging (HR-VWI) of the intracranial vasculature may aid in the diagnosis and management of Moyamoya Disease (MMD). The patterns of HR-VWI findings of the cerebral vasculature of MMD patients remains uncertain, however. We sought to describe HR-VWI findings in a single-center cohort of MMD patients. Methods: Consecutive patients who were evaluated at a Midwest American medical center with a HR-VWI exam were included. Fourteen anterior circulation arterial segments in each patient were analyzed: proximal and distal supraclinoid Internal Carotid Artery, proximal M1 segment of the Middle Cerebral Artery, mid-portion of the M1, distal M1, proximal A1 segment of the Anterior Cerebral Artery and distal A1. Imaging variables that were collected from each segment included the presence of wall thickening (concentric vs eccentric), degree and pattern (concentric or eccentric) of contrast enhancement, and presence of positive or negative vessel remodeling. The total number and percentage of vessel segments demonstrating these characteristics were calculated. The number and percentage of patients with at least one segment demonstrating these characteristics were calculated. Results: Thirty-six patients (32 females, 88.9%) with a diagnosis of MMD were included. Overall, 221 of 504 segments (43.8%) demonstrated negative remodeling in 29 (75%) patients. Ninety-eight segments (19.4%) demonstrated wall enhancement (71 concentric, 27 eccentric; 22 high grade, 76 low grade) in 32 (88.9%) patients. Eighty-seven segments (17.3%) demonstrated wall thickening (52 concentric, 35 eccentric) in 32 patients (88.9%). Conclusions: Negative remodeling was the most-commonly observed vessel wall abnormality in all segments analyzed. However, a high percentage of patients had at least one segment demonstrating wall enhancement, wall thickening and negative remodeling. Continued study is necessary to further elucidate the HR-VWI patterns of the cerebral arterial system in MMD patients.

Identifying Cerebral Large Vessel Occlusion in Acute Ischemic Stroke by MRI Positioning Scanning.

Various approaches have been tried for acute ischemic stroke (AIS) treatment to shorten the time from onset to recanalization. MRI positioning scanning (PS), which must be taken before any MRI sequences, was examined whether it can detect cerebral large vessel occlusion. A total of 68 consecutive patients with AIS who underwent MRI and were treated with intravenous recombinant tissue plasminogen activator or mechanical thrombectomy at our hospital were retrospectively included in this study. Occluded vessels were identified on the axial or coronal views of PS images, and these images were compared with 3D time-of-flight MRA and digital subtraction angiogram. The sensitivities, positive predictive values (PPVs), and negative predictive values (NPVs) for internal carotid artery (ICA), the proximal M1, distal M1, and M2 segment of the middle cerebral artery occlusion were assessed, and the number of PS slices was assessed. The sensitivities of the axial slices for ICA, proximal M1, distal M1, and M2 occlusion were 62%, 21%, 35%, and 86%, respectively. The PPVs of the axial slices for ICA, proximal M1, distal M1, and M2 occlusion were 81%, 88%, 100%, and 97%, respectively, and the NPVs of the axial slices for ICA, proximal M1, distal M1, and M2 occlusion were 94%, 90%, 86%, and 100%, respectively. The detection rate for the ICA was significantly higher with three axial slices (91%) than with two slices (47%) (p <0.01). MRI PS is warranted to be referred to detect large cerebral vessel occlusion.

A Rare Case of Myocarditis, Intracardiac Thrombus And Embolic Stroke Caused By Mycoplasma Pneumoniae

Introduction Cardiac, thrombotic and neurological complications of Mycoplasma pneumoniae infection are uncommon. We describe a rare case of mycoplasma pneumoniae myocarditis complicated by acute systolic heart failure, left ventricular thrombus and embolic stroke. Case A previously healthy 37-year old man presented with a three-week history of sore throat, orthopnea and exertional dyspnea. Examination revealed an apical systolic 2/6 murmur and bilateral lower extremity pitting edema. He had elevated troponin (0.39 ng/ml, normal 0-0.03 ng/ml) and brain natriuretic peptide (BNP) levels (2500 pg/ml, normal 0-100 pg/ml). Rapid streptococcal Group A test was negative. Electrocardiogram was unremarkable. Chest X-ray revealed cardiomegaly with no evidence of pneumonia or edema. Transthoracic echocardiography showed severe left ventricular dilatation, reduced ejection fraction (10%), moderate to severe mitral regurgitation and an apical left ventricular thrombus. He was managed with diuretics and heparin infusion. Based on the clinical and laboratory findings, a diagnosis of myocarditis with acute systolic heart failure was made. Workup for Epstein-Barr virus, human immunodeficiency virus, cytomegalovirus, coxsackievirus, mycoplasma, serum protein electrophoresis, antinuclear antibody and amyloidosis revealed a positive mycoplasma IgM, so he was started on azithromycin. On the second day of hospitalization, he developed a stroke. MRI brain revealed a large acute infarction in the left middle cerebral artery (MCA) territory and multiple small areas in both cerebral hemispheres consistent with an embolic pattern, likely due to the dislodged emboli from the intracardiac thrombus. MR angiogram head showed left MCA proximal M1 segment occlusion. His elevated international normalized ratio (INR) prevented the administration of recombinant tissue plasminogen activator, so he was placed on therapeutic hypothermia and intubated. He then developed cardiogenic shock and unfortunately passed away. Discussion Extrapulmonary manifestations of mycoplasma pneumoniae may be due to the direct invasion of the bacteria, an autoimmune response or vascular occlusion leading to vasculitis or thrombosis. Macrolides and second generation tetracyclines like doxycycline are the drugs of choice. Further studies are needed to explore the autoimmune mechanism and the use of immunosuppressants. Conclusion A high degree of suspicion for mycoplasma pneumoniae should be maintained in a young patient with features of myocarditis and cardiac thrombus to prevent potentially fatal cardiac and cerebrovascular complications.

Application of flow diverters in the treatment of aneurysms in the internal carotid artery bifurcation region.

The treatment of aneurysms in the internal carotid bifurcation region (ICABR), including aneurysms of the true internal carotid artery (ICA) terminus, those inclined on the proximal A1 or M1 segments or at the most distal pre-bifurcation (ICA) segment, is often challenging in microsurgical clipping and endovascular surgery. Few reports had discussed flow diversion as a therapeutic option for this group. This was a retrospective study analysing flow diversion in treating ICABR aneurysms. Seven patients harbouring eight aneurysms in the ICABR were treated with flow diversion. Five aneurysms were inclined on the proximal A1 segment, and three were located at the most distal pre-bifurcation segment. Patients' demographics, presentation, procedure technical description, angiographic and clinical follow-up were recorded. PubMed and Ovid MEDLINE were also reviewed for articles published in English, including case series or case reports, for ICABR aneurysms treated with flow diverters. All patients except one underwent angiographic follow-up. The Karman-Byrne occlusion scale was used to determine the occlusion rate. All six patients with documented angiographic follow-up had a class IV occlusion score. No permanent or transient neurological or non-neurological complications were encountered in this study. Treating ICABR aneurysms using flow diversion is feasible, with a promising angiographic occlusion rate. Further studies are needed to analyse long-term clinical and angiographic results.

Mechanical thrombectomy in acute middle cerebral artery M2 segment occlusion with regard to vessel involvement.

Endovascular treatment (EVT) is an established procedure in patients with acute ischemic stroke due to occlusion of the proximal M1-segment of middle cerebral artery. The assessment of distal thrombectomy in daily clinical routine has not yet been sufficiently evaluated. Patients with M2-segment-occlusions treated by EVT in the local department (January 2012-December 2017) were included (n= 57, mean National-Institutes-of-Health-Stroke-Scale of 11, range 0-20). Patients were grouped according to localization of M2-occlusion (Cohort A (n= 14): central region only, B (n= 24): central region and involvement of frontal vessels, C (n= 19): parietal, occipital, and/or temporal vessels). Differences in proximal (M2-trunk, n= 34) and distal (M2-branches, n= 23) occlusions were also examined. Reperfusion (Thrombolysis-In-Cerebral-Infarction (TICI)), early clinical outcome at discharge (modified Rankin Scale (mRS)), and complications (hemorrhage, new emboli) were noted. Successful reperfusion (TICI2b-3) was found in 49 patients (86.0%). Favorable early clinical outcome (mRS0-2) was achieved in n= 19 (37.7%). Compared to admission, mRS at discharge improved significantly (median (admission) 5 vs. median (discharge) 4, p< 0.001). Early clinical outcome was more favorable in patients with better reperfusion (TICI2b-3: mean mRS 3 ± 1.7 vs. TICI0-2a: mean mRS 4.4 ± 1.4, p= 0.037). Six (10.5%) patients suffered from symptomatic intracranial hemorrhage during treatment or hospitalization. Four patients died (7.0%). No significant differences in favorable clinical outcome (mRS ≤ 2: Cohort A 42.9%, B 50.0%, C 16.7%, p=0.4; χ2-test) or periinterventional complications were found with regard to vessel involvement. EVT in patients with acute M2-occlusion is safe and leads to a significant clinical improvement at discharge. No significant differences in clinical outcome or complications were found with regard to the localization of the M2-occlusion.

Effect of direct angioplasty therapy on acute middle cerebral artery occlusion with good leptomeningeal collateral

ObjectiveThe objective of this study was to investigate and discuss the effect of direct angioplasty therapy on acute middle cerebral artery occlusion (MCAO) patients with good leptomeningeal collateral circulation in 4.5 h. Patients and MethodsWe retrospectively reviewed our acute ischemic stroke database from January 2017 to January 2019, then selected consecutive patients with evidence of the proximal M1 segments of MCAO and good leptomeningeal collateral who have received angioplasty or mechanical thrombectomy (MT). The baseline characteristics and outcome of patients was statistical analysis, included age, gender and risk factors, baseline national institutes of health stroke scale (NIHSS) scores, preoperative alberta stroke programme early CT (ASPECT) score, time from door to needle, time of door to puncture, endovascular procedure time, 7d NIHSS score and the modified treatment in cerebral infarction (m-TICI) 2b or 3, symptomatic hemorrhage, average hospital stays, modified rankin scale (mRS) score 0–2 at 3-month and mortality. All the thrombi were analyzed by histopathology. All statistical analysis was done with t-test for continuous data and χ2 test for binary data. ResultsA total of 93 patients were included (direct angioplasty = 41 (44.1 %), MT = 52 (55.9 %)). There was no significant difference in baseline data between the two groups. The difference in the time of door to recanalization, the time of puncture to recanalization, symptomatic hemorrhage, and average hospital stays were significantly different between groups (P < 0.05). The other agents were not significantly different between groups (P > 0.05 each). Histopathological analysis showed all thrombi contained different amounts of platelets, fibrinogen, white blood cell, and red blood cell. ConclusionDirect angioplasty therapy on acute MCAO with good leptomeningeal collateral may help to shorten the time of surgery, reduce symptomatic hemorrhage, and hospital stay.

Abstract TP5: Mr Predicts a Reliable and Useful Tool in Identifying Benefit of Mechanical Thrombectomy in Patients With Large Vessel Occlusion

Background: The AHA/ASA guideline recommends endovascular therapy for patients with acute ischemic stroke within 6 hours from symptom onset. Identification of the patients most likely to benefit (and those most likely to be harmed) from reperfusion plays a pivotal role in decision-making. We applied the MR PREDICTS tool (clinical decision making tool derived from MR CLEAN clinical trial) on a real-world sample of patients with acute ischemic stroke to assess its utility in predicting clinical benefit from endovascular therapy. Methods: We identified all patients with acute ischemic stroke with occlusion of the distal internal carotid artery, proximal M1, or M2 segment of the middle cerebral artery who underwent endovascular reperfusion procedure (thrombectomy and/or intra-arterial thrombolysis) from July 2016 to June 2017. Patients were divided into two groups; those with a good outcome (90 Day mRS 0-2) and those with a poor outcome (90 Day mRS 3-6). The MR PREDICTS tool was used to determine absolute treatment benefit for each patient. This predicted outcome was compared to actual patient outcome. Results: A total of 22 patients were identified. Eight patients had a good outcome and 14 patients had a poor outcome. The calculated absolute treatment benefit from endovascular therapy using the MR PREDICTS tool was consistently higher among patients in the good outcome group, with an average absolute treatment benefit of 12% greater among these patients compared to those in the poor outcome cohort (19% versus 7%). Of note, patients with a poor outcome had a higher rate of prior stroke, higher baseline NIHSS, longer symptom onset to groin puncture time, less favorable collaterals and lower rate of successful recanalization defined as TICI 2b or 3 (100% versus 64%). Conclusion: There is a strong correlation between predicted treatment benefit by MR PREDICTS tool and actual patient outcomes which supports broader use of this tool during the decision-making process for endovascular therapy in patients with acute ischemic stroke.

Internal Carotid Artery and the Proximal M1 Segment Are Optimal Targets for Mechanical Thrombectomy

Background and Purpose: Mechanical thrombectomy (MT) is an established treatment of acute anterior circulation stroke caused by large vessel occlusion (LVO). We compared the clinical outcome (3-month modified Rankin Scale, mRS) in hyperacute (<3h from the onset of symptoms) ischemic stroke between an MT and an intravenous thrombolysis (IVT) cohort in proximal (ICA and the proximal M1 segment of the middle cerebral artery) and distal (the distal M1 and the M2 segment) LVOs. Methods: We prospectively reviewed 67 patients who underwent MT with newer-generation stent retrievers. The IVT cohort consisted of 98 patients who received IVT without MT. We recorded baseline clinical, procedural and imaging variables, technical outcome, 24-h imaging outcome, and the clinical outcome. Differences between the groups were studied with theoretically appropriate statistical tests and binary logistic regression analysis. Results: The proportion of patients who had a proximal LVO and experienced good (mRS ≤2) or excellent (mRS ≤1) clinical outcome was significantly larger in the MT group (62 vs. 7%, p < 0.001; 47 vs. 3%, p < 0.001, respectively). In a regression model including relevant confounding variables, good clinical outcome was seen significantly more often among patients with proximal occlusions (OR = 6.0, CI 95% 1.9-18.3, p = 0.002). In a similar model, no statistically significant differences were observed in patients with more distal occlusions. Conclusions: MT is superior to IVT in achieving good clinical outcome in hyperacute anterior circulation stroke in the most proximal occlusions (ICA and proximal M1 segment). In the distal M1 and M2 segments neither of these therapies clearly outperforms the other.

Time-resolved 3D Rotational Angiography (4D DSA) of the Lenticulostriate Arteries: Display of Normal Anatomic Variants and Collaterals in Cases with Chronic Obstruction of the MCA.

The lenticulostriate arteries (LSA) and other perforators may play arole for collateral supply in cases with ischemia due to stenosis or occlusions of the middle cerebral artery (MCA). Purpose of this case series was to evaluate the potential of time-resolved 3D rotational angiography data sets (4D DSA) for detailed visualization of anatomic variants of LSA feeders and for display of local collaterals involving the LSA in cases with chronic MCA obstruction. Multiplanar and volume rendering reconstructions of 4D DSA data were computed in addition to standard postprocessing in 24patients who had indications for 3D rotational angiography (3DRA) of the internal carotid artery (ICA) without pathologies of the ICA, middle cerebral artery (MCA) and anterior cerebral artery (ACA) main stems (n= 18) or with stenosis or chronic occlusion of the MCA (n= 6). For acquisition of 3DRA, we used amodified digital subtraction angiography (DSA) image acquisition protocol with an extended rotation angle of 260° and aprolonged scan time of 12 s on aSiemens Axiom Artis Zee biplane neuroangiography equipment. The 4D reconstructions of existing 3DRA data were computed on adedicated workstation. Origin and course of LSA and other perforators were analyzed according to coronal multiplanar reconstructions (MPRs) with slice thicknesses between 6 and 28 mm. In all cases 4D reconstructions of the LSA were technically feasible and evaluable. As expected, origin and course of LSA showed awide range of variations: The most common pattern was acommon trunk dividing into multiple ascending branches originating from the proximal M1 (n= 5) or the proximal A1segment (n= 4). Alternatively, 8patients showed several individual branches that directly originated from the proximal M1segment of the MCA and occasionally from the A1segment of the ACA. In patients with M1stenosis or occlusion, 4 out of 6cases had local collaterals with involvement of proximal LSA trunks and anetwork parallel to the obstructed vessel segment. The 4D reconstructions were found to be equivalent (n= 16) or superior to 3D reconstructions (n= 8). The 4D DSA reconstructions provide areliable display of normal LSA variants and connections to local collateral networks in cases with chronic MCA obstruction. The possibility to select acorrect angiographic phase is advantageous compared to 3D DSA.

Abstract WP430: Endothelial Cell Collection from Ipsilateral Middle Cerebral Artery in Acute Ischemic Stroke

Introduction: The cerebrovascular endothelium plays a critical role in the pathogenesis of and response to acute ischemic stroke (AIS). To date, techniques to study its function have relied on animal and in vitro models. A robust method of endothelial cell (EC) capture in patients with AIS at early time points, from within the ischemic region, could greatly advance our understanding of cerebrovascular injury. Method: Patients undergoing thrombectomy for middle cerebral artery occlusion (MCA) within 8 hours of onset were offered enrollment if the pass of their stent-retriever device occurred directly into a distal access catheter in the proximal M1 segment, limiting exposure of the device to only the MCA. After retrieval, ECs adherent to the devices were retrieved and stained for EC (CD31) and leukocyte (CD45) markers. EC identity and yield were confirmed by flow cytometry with simultaneous immuno-fluorescence microscopy. Cultured human ECs were used as positive controls. The EC fraction was defined as CD31 + CD45 - with size and morphological features consistent with the positive controls. Results: ECs from stent-retriever devices (n=3) were collected and pooled. Approximately 8% of the collected cells represented ECs. EC collected from the stent-retrievers demonstrated highly similar shape, morphology and antibody staining patterns compared to the positive controls (Figure). Conclusions: Here we provide the first demonstration of a rapid post-thrombectomy method for reliable harvesting of cerebral ECs in humans. The ability to capture these cells in patients with AIS within hours of symptom onset opens many avenues of exploration for determining the role of ECs in AIS.

Predictors of Symptomatic Intracranial Hemorrhage after Endovascular Therapy in Acute Ischemic Stroke with Large Vessel Occlusion

The symptomatic intracranial hemorrhage (SICH) is a serious complication of endovascular therapy (EVT) in acute ischemic stroke (AIS) with large vessel occlusion. We aimed to clarify the predictors of SICH after EVT in patients with internal carotid artery (ICA) or proximal M1 segment of middle cerebral artery occlusions. Among 1442 AIS patients with large vessel occlusion admitted within 24 hours after onset between July 2010 and June 2011, 226 patients with ICA or proximal M1 occlusions were treated with EVT. SICH was defined as any type of intracranial hemorrhage with a decline in the National Institutes of Health Stroke Scale (NIHSS) score ≥4. Of the 226 patients, 204 with sufficient data were analyzed. SICH was observed in 10 patients (4.9%). Baseline NIHSS score (22 versus 17), serum glucose level (206 mg/dL versus 140 mg/dL), and prior antiplatelet therapy (60.0% versus 21.7%) were significantly higher in patients with SICH than in those without (all P < .01). With receiver operating characteristic analyses, the optimal cutoff values for predicting SICH were NIHSS score ≥19 and serum glucose ≥160 mg/dL. In multivariate analysis, glucose level ≥160 mg/dL (odds ratio: 11.89; 95% confidence interval [CI]: 2.79-65.08), prior antiplatelet therapy (odds ratio: 8.03; 95% CI: 1.83-41.70), and NIHSS score ≥19 (odds ratio: 7.78; 95% CI: 1.63-59.44) were independent predictors of SICH. Hyperglycemia, prior antiplatelet therapy, and high baseline NIHSS score were associated with SICH after EVT in AIS patients with ICA or proximal M1 occlusions.

TREVO and Capture LP have equal technical success rates in mechanical thrombectomy of proximal and distal anterior circulation occlusions

PurposeMechanical thrombectomy (MT) is a proven method to treat large vessel occlusions in acute anterior circulation stroke. We compared the technical, imaging, and clinical outcomes of MT performed with either...