Abstract Number ‐ 236: Pure Arterial Malformations: A Case Report

Introduction Pure arterial malformations are dilated, overlapping, and tortuous arteries forming a mass of arterial loops without a venous component. These malformations are rare, with limited cases reported in the literature. Affecting any of the intracranial arteries, they are usually found incidentally and often have a benign course. Methods We present a case of a pure arterial malformation in a young female with hyperprolactinemia. Furthermore, we review the literature and provide an updated summary of these malformations. Results A 28‐year‐old female with a history of infantile hemangiomas, polycystic ovary syndrome, and hyperprolactinemia presented with acne, mild hirsutism, and galactorrhea. Her neurological exam was normal. Magnetic Resonance Imaging (MRI) of the brain with and without contrast ruled out a prolactinoma but revealed a 3 cm vascular malformation at the margin of the left cavernous sinus extending posteriorly into the anterior left perimesencephalic cistern. Initial differentials included a pial arteriovenous malformation or less likely a dural arteriovenous fistula. She underwent a diagnostic cerebral angiogram which revealed a pure arterial malformation without arteriovenous shunting. This was composed of dysplasia of the left posterior communicating artery and anterior choroidal arteries. Stenosis of the left internal carotid artery distally with collateral support into the left anterior cerebral artery and middle cerebral artery was also noted. Lesser changes were noted in the right side with reconstitution of the right anterior cerebral artery from collaterals. Genetic testing for vascular malformation syndromes, including genes known to be associated with hereditary hemorrhagic telangiectasia, was negative. Repeat MRI/MRA done 8 months from the initial scan was stable with no abnormal large arterial venous shunting or definite saccular aneurysm formation noted. Conclusions Although rare, pure arterial malformations should be considered in the differential diagnosis for patients presenting with a cranial vascular malformation. Management of these lesions is usually conservative given their lack of arteriovenous shunting and low risk of rupture, with only a few cases undergoing surgery or endovascular treatment

Abstract Number ‐ 211: Flow Diversion in Direct Carotid‐Cavernous Fistulas: Case Report and Literature Review

Introduction Direct carotid‐cavernous fistulas (dCCF) are acquired, abnormal high‐flow connections between the internal carotid artery and cavernous sinus. Interventions are often required due to the high risk of incipient morbidity and mortality if left untreated. Treatment approaches have rapidly evolved over time, and have included the use of detachable balloons, liquid embolic agents, and coil embolization through transarterial, transvenous, or combined approaches. Case series level data support an emerging role for the use of flow diversion (FD) as a stand‐alone or adjunctive treatment in dCCFs. We describe a case of FD use as an adjunctive treatment in a patient with a treatment‐resistant dCCF, and review the literature on FD use in dCCF. Methods We describe the clinical course, imaging findings, and outcomes of a 25‐year old patient who presented with a traumatic carotid‐cavernous fistula requiring multiple interventions. We also performed a literature review of Pubmed and Embase databases using combinations of MeSH and key terms to include all relevant full‐text publications of FD use in the treatment of dCCFs, up to and including February 2022. Results Our patient achieved angiographic cure and significant improvement in symptoms at 6‐month follow‐up. A total of 24 papers were identified and included, for a total number of 53 cases (23 male, 23 female, 7 unspecified). The median age of patients was 44 years (Interquartile range (IQR) 23–62). The etiology of the dCCF was traumatic (acute or as a delayed presentation) in 31 cases (58%), spontaneous in 10 cases (19%), and iatrogenic in 12 cases (23%). FD was the primary mode of treatment of the CCF in approximately half of cases (27, 51%), and was a stand‐alone treatment modality in one third of cases (18, 34%). The median number of FD devices used on initial treatment was 1 device, though retreatment was needed in 42% of cases.Angiographic resolution was achieved in 90% of cases at a median follow‐up duration of 6 months.One half of all patients had complete resolution of symptoms and a further third noted clinical improvement in at least some of their symptoms. In 10% of cases, symptoms persisted, or other complications developed that were attributed to concurrent injuries. Conclusions Treatment approaches for dCCFs have evolved over time as safer and more effective treatments become available. There is an emerging role for FD as a safe stand‐alone or adjunctive treatment option for dCCFs. Our case further supports its role in treatment‐resistant fistulas with high‐risk features. As treatment approaches continue to evolve, prospective randomized data is needed to better establish the role of flow divertors among the hierarchy of available treatment options for dCCFs

Symmetric collateral pattern on CTA predicts favorable outcomes after endovascular thrombectomy for large vessel occlusion stroke.

Endovascular thrombectomy (EVT) has revolutionized large vessel occlusion (LVO) stroke management, but often requires advanced imaging. The collateral pattern on CT angiograms may be an alternative because a symmetric collateral pattern correlates with a slowly growing, small ischemic core. We tested the hypothesis that such patients will have favorable outcomes after EVT. Consecutive patients (n = 74) with anterior LVOs who underwent EVT were retrospectively analyzed. Inclusion criteria were available CTA and 90-day modified Rankin Scale (mRS). CTA collateral patterns were symmetric in 36%, malignant in 24%, or other in 39%. Median NIHSS was 11 for symmetric, 18 for malignant, and 19 for other (p = 0.02). Ninety-day mRS ≤2, indicating independent living, was achieved in 67% of symmetric, 17% of malignant, and 38% of other patterns (p = 0.003). A symmetric collateral pattern was a significant determinant of 90-day mRS ≤2 (aOR = 6.62, 95%CI = 2.24,19.53; p = 0.001) in a multivariable model that included age, NIHSS, baseline mRS, thrombolysis, LVO location, and successful reperfusion. We conclude that a symmetric collateral pattern predicts favorable outcomes after EVT for LVO stroke. Because the pattern also marks slow ischemic core growth, patients with symmetric collaterals may be suitable for transfer for thrombectomy. A malignant collateral pattern is associated with poor clinical outcomes

Abstract Number ‐ 34: Basal ganglia infarct volume and risk of hemorrhagic transformation after endovascular thrombectomy

Introduction As more large vessel occlusion stroke patients are treated with endovascular thrombectomy (EVT), understanding the pathophysiology of reperfusion injury and the risks of hemorrhagic transformation (HT) are increasingly important. Pre‐EVT infarct topography may have implications for acute interventional treatments such as stenting, and post thrombectomy care such as antithrombotic choice. We sought to quantify region‐specific volumes of infarcted tissue on pre‐EVT MRI, understand their importance for HT, and identify associations with clinical and imaging characteristics. Methods Patients with pre‐EVT MRI were identified retrospectively from a prospectively maintained database. Each patient’s diffusion weighted sequence underwent manual infarct delineation and was registered to a standard space for overlay with cortical, subcortical, and white matter atlases. Structure‐specific lesion volumes were determined. HT was defined as PH1 or PH2 hemorrhage by ECASS criteria. Variables with p< 0.10 in univariate analyses were included in multivariable models. Logistic regression was performed for associations with hemorrhagic transformation and linear regressions for infarct volumes. Results 165 participants [median age 69 years (interquartile range, IQR 56–79), 56% women] were identified. Risk factors included hypertension (70%), diabetes (20%), atrial fibrillation (34%), and prior stroke/TIA (13%). 52% were treated with intravenous alteplase; 70% achieved TICI 2b‐3 reperfusion. HT occurred in 8%. Pre‐EVT infarct volumes [median (IQR)] were 22 cc (12‐43 cc) for total, 11 cc (6‐19 cc) for white matter, 5 cc (1‐19 cc) for cortex, and 3 cc (1‐6 cc) for basal ganglia. Pre‐EVT infarcts [median (IQR)] were made up of 48% (38‐60%) white matter, 23% (6‐47%) cortex, and 15% (4‐28%) basal ganglia. Paramagnetic sequences showed 3% had petechial hemorrhage and 40% had susceptibility vessel sign. Basal ganglia infarct volume was independently associated with HT (OR = 1.342, 95%CI = 1.002,1.797) in a model including white matter infarct volume, cortex infarct volume, smoking, and puncture‐recanalization time. Basal ganglia infarct volume was linked to susceptibility vessel sign (Beta = 0.233, p = 0.006) and NIHSS (Beta = 0.220, p = 0.012), when controlling for total infarct volume. Conclusions In this cohort, greater basal ganglia infarct volume was associated with a higher risk of hemorrhagic transformation, even when accounting for infarct volume in other regions. Susceptibility vessel sign was associated with basal ganglia infarct volume, which may be related to acute middle cerebral artery thrombus occlusion of perforators. These findings require further study in larger cohorts

Abstract 251: Characterizing coma in patients presenting with large vessel occlusion stroke

Introduction Coma is an unresponsive state of disordered consciousness characterized by impaired arousal and awareness. The epidemiology and pathophysiology of coma in ischemic stroke has been underexplored. We sought to characterize the incidence and clinical features of coma as a presentation of large vessel occlusion (LVO) stroke. Methods Individuals who presented with LVO were retrospectively identified from July 2018 to December 2020. Coma was defined as an unresponsive state of impaired arousal and awareness, operationalized as a score of 3 on NIH Stroke Scale (NIHSS) item 1a. Results A total of 28/637 (4.4%) patients with LVO stroke were identified as presenting with coma. The median NIHSS was 32 (IQR 29‐34) for those with coma versus 11 (5‐18) for those without (p<0.0001). In coma, occlusion locations included basilar (13), vertebral (2), internal carotid (5), and middle cerebral (9) arteries. 8/28 were treated with endovascular thrombectomy (EVT), and 20/28 died during the admission. 65% of patients not treated with EVT had delayed presentations or large established infarcts. In models accounting for pre‐stroke modified Rankin Scale (mRS) score, basilar artery occlusion location, intravenous thrombolysis, and EVT, coma independently increased the odds of transitioning to comfort care during the admission (aOR 6.75; 95%CI 2.87,15.84; p <0.001) and decreased the odds of 90‐day mRS 0‐2 (aOR 0.12; 95%CI 0.03,0.55; p=0.007). Conclusion It is not uncommon for patients with LVO to present with coma, and delayed recognition of LVO can lead to poor outcomes, emphasizing the need for maintaining a high index of suspicion. While more commonly thought to result from posterior LVO, coma in our cohort was similarly likely to result from anterior LVO. Efforts to improve early diagnosis and care of patients with LVO presenting with coma are crucial, given the poor outcomes

Direct to Angio‐Suite Large Vessel Occlusion Stroke Transfers Achieve Faster Arrival‐to‐Puncture Times and Improved Outcomes

Background For patients with large vessel occlusion (LVO) stroke, time to treatment with endovascular thrombectomy is crucial to prevent infarction and improve outcomes. We sought to evaluate the hub arrival‐to‐puncture times and outcomes for transferred patients accepted directly to the angio‐suite (LVO to operating room, LVO2OR) versus those accepted through the emergency department in a hub‐and‐spoke telestroke network. Methods Consecutive patients transferred for endovascular thrombectomy with spoke computed tomography angiography–confirmed LVO, spoke Alberta Stroke Program Early Computed Tomography score >6, and last known well–to–hub arrival <6 hours were identified. Our LVO2OR protocol began implementation in January 2017. The LVO2OR cohort includes patients who underwent endovascular thrombectomy from July 2017 to October 2020; the emergency department cohort includes those from January 2011 to December 2016. Hub arrival‐to‐puncture time and 90‐day modified Rankin scale score were prospectively recorded. Results The LVO2OR cohort was composed of 91 patients, and the emergency department cohort was composed of 90 patients. LVO2OR patients had more atrial fibrillation (51% versus 32%; P=0.02) and more M2 occlusions (27% versus 10%; P=0.01). LVO2OR patients had faster median hub arrival‐to‐puncture time (11 versus 92 minutes; P<0.001), faster median telestroke consult‐to‐puncture time (2.4 versus 3.6 hours; P<0.001), greater Thrombolysis in Cerebral Infarction score 2b to 3 reperfusion (92% versus 69%; P<0.001), and greater 90‐day modified Rankin scale score <2 (35% versus 21%; P=0.04). In a multivariable model, LVO2OR significantly increased the odds of 90‐day modified Rankin scale score <2 (adjusted odds ratio, 2.77 [95% CI, 1.07–7.20]; P=0.04) even when controlling for age, baseline modified Rankin scale score, atrial fibrillation, National Institutes of Health Stroke Scale score, M2 occlusion location, and Thrombolysis in Cerebral Infarction score 2b to 3. Conclusions In a hub‐and‐spoke telestroke network, accepting transferred patients directly to the angio‐suite was associated with dramatically reduced hub arrival‐to‐puncture time and may lead to improved 90‐day outcomes. Direct–to–angio‐suite protocols should continue to be evaluated in other geographic regions and telestroke network models

Characterizing Reasons for Stroke Thrombectomy Ineligibility Among Potential Candidates Transferred in a Hub‐and‐Spoke Network

Background Access to endovascular thrombectomy (EVT) is relatively limited. Hub‐and‐spoke networks seek to transfer appropriate large‐vessel occlusion stroke candidates to EVT‐capable hubs. However, some patients are ineligible upon hub arrival, and factors that drive transfer inefficiencies are not well described. We sought to quantify EVT transfer efficiency and identify reasons for EVT ineligibility. Methods Consecutive EVT candidates presenting to 25 spokes from 2018 to 2020 with pretransfer computed tomography angiography‐defined large‐vessel occlusion and Alberta Stroke Program Early Computed Tomography Score of ≥6 were identified from a prospectively maintained database. Outcomes of interest included hub EVT, reasons for EVT ineligibility, and 90‐day modified Rankin scale score of ≤2. Results Among 258 patients, the median age was 70 years (interquartile range, 60–81 years); 50% were women. A total of 56% were ineligible for EVT after hub arrival. Cited reasons were large established infarct (49%), mild symptoms (33%), recanalization (6%), distal occlusion (5%), subocclusive lesion (3%), and goals of care (3%). Late window patients (last known well >6 hours) were more likely to be ineligible (67% versus 43%; P<0.0001). EVT‐ineligible patients were older (73 versus 68 years; P=0.04), had lower National Institutes of Health Stroke Scale score (10 versus 16; P<0.0001), had longer last known well‐to‐hub arrival time (8.4 versus 4.6 hours; P<0.0001), had longer spoke Telestroke consult‐to‐hub arrival time (2.8 versus 2.2 hours; P<0.0001), and received less intravenous thrombolysis (32% versus 45%; P=0.04) compared with eligible patients. EVT ineligibility independently reduced the odds of 90‐day modified Rankin scale score of ≤2 (adjusted odds ratio, 0.26; 95% CI, 0.12–0.56; P=0.001) when controlling for age, National Institutes of Health Stroke Scale score, and last known well‐to‐hub arrival time. Conclusions Among patients transferred for EVT, there are multiple reasons for ineligibility upon hub arrival, with most excluded for infarct growth and mild symptoms. Understanding factors that drive transfer inefficiencies is important to improve EVT access and outcomes

Spoke‐Administered Thrombolysis Improves Large‐Vessel Occlusion Early Recanalization: The Real‐World Experience of a Large Academic Hub‐and‐Spoke Telestroke Network

Background Intravenous thrombolysis (IVT) before mechanical thrombectomy (MT) for large‐vessel occlusion (LVO) stroke is increasingly controversial. Recent trials suggest MT without IVT is reasonable for patients presenting directly to MT‐capable “hub” centers. However, bypassing IVT has not been evaluated for patients presenting to IVT‐capable “spoke” hospitals that require hub transfer for MT. A perceived lack of efficacy of IVT to result in LVO early recanalization (ER) is often cited to support bypassing IVT, but data for IVT in patients who require interhospital transfer are limited. Here, we examined LVO ER rates after spoke‐administered IVT in our hub‐and‐spoke stroke network. Methods Patients presenting to 25 spokes before hub transfer for MT consideration from 2018 to 2020 were retrospectively identified from a prospectively maintained database. Inclusion criteria were pretransfer computed tomography angiography–defined LVO, Alberta Stroke Program Early Computed Tomography Score ≥6, and posttransfer repeat vessel imaging. Results Of 167 patients, median age was 69, and 51% were women. Seventy‐six received spoke IVT, and 91 did not. Alteplase was the only IVT used in this study. Comorbidities and National Institutes of Health Stroke Scale were similar between groups. ER frequency was increased 7.2‐fold in patients who received spoke IVT (12/76 [15.8%] versus 2/91 [2.2%]; P<0.001]. Spoke‐administered IVT was independently associated with ER (adjusted odds ratio, =11.5 [95% CI, 2.2–99.6; P<0.05) after adjusting for the timing of last known well, interhospital transfer, and repeat vessel imaging. Interval National Institutes of Health Stroke Scale score was improved in patients with ER (median −2 [interquartile range, −6.3 to −0.8] versus 0 [−2.5 to 1]; P<0.05). Conclusion Within our network, patients who received spoke IVT had a 7.2‐fold increased ER relative likelihood. This real‐world analysis supports IVT use in eligible patients with LVO at spoke hospitals before hub transfer for MT

Abstract 1122‐000031: Reasons Thrombectomy Candidates Become Ineligible After Transfer for Treatment in a Hub‐And‐Spoke Telestroke Model

Introduction: The care of emergent large vessel occlusion (ELVO) stroke patients has been revolutionized by endovascular thrombectomy (EVT). Given its robust efficacy, it is crucial to optimize delivery to eligible patients. Within hub‐and‐spoke hospital system models, some patients first present to distant spoke hospitals and require transfer to hub hospitals for EVT. We sought to understand reasons EVT candidates become ineligible after transfer for treatment. Methods: Consecutive EVT candidates presenting to 25 spokes from 2018 to 2020 with pre‐transfer CTA‐defined ELVO and Alberta Stroke Program Early CT Score ≥6 were identified from a prospectively maintained database. Outcomes of interest included hub EVT, reasons for EVT ineligibility, and 90‐day functional independence (modified Rankin Scale, mRS ≤2). Results: 258 patients were identified with median age 70 years (IQR 60–81) and 50% female. 44% underwent EVT upon hub arrival, of which 87% achieved Thrombolysis in Cerebral Infarction 2b‐3 reperfusion. Compared to EVT‐eligible patients, ineligible patients were older (73 vs 68 years, p = 0.04), had lower NIH Stroke Scale (NIHSS, 10 vs 16, p<0.0001), longer LKW‐hub arrival time (8.4 vs 4.6 hours, p<0.0001), and received less IV alteplase (32% vs 45%, p = 0.04). The clinical reasons cited for becoming EVT ineligible upon hub arrival included large established infarct (49%), mild symptoms (33%), recanalization (6%), distal occlusion location (5%), subocclusive lesion (3%), and goals of care (3%). Becoming EVT ineligible independently reduced the odds of 90‐day functional independence (aOR = 0.26, 95%CI = 0.12,0.56; p = 0.001), even when controlling for age, NIHSS, and LKW‐hub arrival time. Conclusions: Approaches to increase EVT eligibility among ELVO transfers may improve long term outcomes. A primary reason for becoming EVT ineligible is infarct growth. Future studies should explore triaging patients directly to EVT‐capable hubs when feasible, improving inter‐hospital transfer times, supporting ischemic penumbra before EVT, and developing novel neuroprotective agents

Impact of Endoluminal Flow Diverter Number on Aneurysm Treatment Outcomes: A Multicenter Study

Background The purpose of this study is to evaluate the impact multiple overlapping flow‐diverting stents have on aneurysm occlusion rates and iatrogenic complications relative to single flow‐diverting stents. Methods A retrospective review of a multicenter aneurysm database from 2012 to 2020 was performed to identify saccular aneurysms treated initially with single and multiple flow‐diverting stents with ≥12‐month angiographic and clinical follow‐up. Aneurysm occlusion rates as a function of stent number served as a primary outcome measure with iatrogenic complications serving as a secondary outcome measure. Results A total of 250 patients were initially treated with a single Pipeline embolization device (PED), and 48 patients were initially treated with multiple PEDs. There was no significant difference in aneurysm size, morphology, or dual‐antiplatelet therapy regimen used between groups. There was no significant difference in the aneurysm occlusion (single, 83.6%, versus multiple, 83.4%; P=0.65) or retreatment rates (single, 8.0%, versus multiple, 10.4%; P=0.58) between groups. There was no significant difference in the number of procedure‐related complications between groups (single, 8.0%, versus multiple, 4.2%; P=0.42), with 0.8% of patients treated with a single PED and 2.1% of patients treated with multiple PEDs experiencing a procedure‐related ischemic stroke. Conclusions There is no significant difference in overall aneurysm occlusion rates between aneurysms treated initially with single versus multiple overlapping PEDs nor are there significant differences in procedure‐related complications. Single PED flow diversion may be preferred whenever possible, with multiple PED constructs reserved for extenuating clinical circumstances as may be encountered with giant aneurysms