Cranial Transposition and Revascularization of Autologous Omentum: A Novel Surgical Technique for Bypassing the Blood Brain Barrier after Resection of Recurrent Glioblastoma Multiforme

Background: Glioblastoma multiforme (GBM) patients continue to suffer a poor prognosis. The blood brain barrier (BBB) comprises one of the obstacles for therapy, creating a barrier that decreases the bioavailability of chemotherapeutic agents in the central nervous system. Previously, a vascularized temporoparietal fascial scalp flap (TPFF) lining the resection cavity was introduced in a trial conducted in our institution, in newly-diagnosed GBM patients in an attempt to bypass the BBB after initial resection. In this paper, we report on a new technique to bypass the BBB after re-resection and potentially to allow tumor antigens to be surveilled by the immune system .Objective: Assess the feasibility of performing a cranial transposition and revascularization of autologous omentum after re-resection of GBM.Methods: Laparoscopically harvested omental free flap was transposed to the resection cavity by a team consisting of neurosurgeons, otolaryngologists, and general surgeons. This was done as part of a single center, single arm, open-label, phase I study.Results: Autologous abdominal omental tissue was harvested laparoscopically on its vascularized pedicle in 2 patients, transposed as a free flap, revascularized using external carotid artery, and carefully laid into the tumor resection cavity. Patients did well postoperatively returning to baseline activities. Graft viability was confirmed by cerebral angiogram. Conclusion: Omental cranial transposition of a laparoscopically harvested, vascularized flap, into the cavity of re-resected GBM patients is feasible and safe in the short term. Further studies are needed to ascertain whether such technique can improve progression free survival and overall survival in these patients.

Endovascular biopsy of a sigmoid sinus lesion using a stent retriever and aspiration catheter

A teenager with a history of acute myeloid leukemia presented with headache, nausea and blurry vision over a 2 week period. The MRI of the brain was concerning for the presence of a myeloid sarcoma within the right sigmoid sinus. For evaluation of venous obstruction and the underlying lesion the patient underwent a cerebral angiogram and transvenous biopsy of the sigmoid sinus lesion using a stent retriever and aspiration catheter. The tissue extracted was consistent with myeloid sarcoma. This pathologic finding was consistent with the recurrence of leukemia and guided the targeted oncologic treatment.

Abstract 1122‐000097: Recurrent Carotid Cavernous Fistula Requiring Complex Repair of Ruptured Cavernous Carotid Aneurysm: A Case Report

Introduction : There are no studies investigating the safety and efficacy of covered stent grafts, particularly the newly developed stents such as the PK Papyrus stent, for endovascular treatment of direct carotid cavernous fistulas (CCFs). Methods : We present a case of a 75‐year‐old female who presented to the hospital with a three‐week history of worsening left eye vision, chemosis, proptosis, and partial third nerve palsy. Patient was found to have left direct Type A CCF secondary to ruptured cavernous segment carotid aneurysm. Results : The CCF was treated with coil embolization and pipeline Shield stent embolization devices with immediate stagnation and improvement of symptoms. Patient had history of an aortic mechanical valve and thus was started on warfarin and ASA. After achieving INR level of 2.5‐3.5, patient started to have recurrent swelling of the left eye associated and decreased visual acuity. Repeated diagnostic cerebral angiogram revealed residual CCF. Onyx liquid embolization and a Surpass Evolve Flow Diverter were attempted to slow the fistulization with no success. Multiple attempts for direct percutaneous superior ophthalmic vein cannulation were also unsuccessful. At this point, two coronary graft‐covered PK Papyrus stents were implanted across the fistula pouch, which resulted in immediate resolution of the CCF with evidence of persistent normal flow within left ophthalmic artery. Patient’s visual acuity and left eye movement improved. Conclusions : This case report highlights the effectiveness and safety of covered stent grafts, particularly more flexible stents such as the PK Papyrus stent, in navigating the carotid vasculature and closing direct CCFs and may be used as a first‐line technique. More large‐scale studies are warranted to investigate the safety and efficacy of using such stent grafts to treat direct CCFs in the setting of antithrombotic agents and anticoagulation.

Abstract 1122‐000187: Acute Stroke, Subarachnoid Hemorrhage, VZV vasculopathy, and Carotid Dissection: An Interesting Case

Introduction : A 51‐year‐old lady with a past medical history of Essential Hypertension, Hypothyroidism, prior Herpes Zoster infection 8 weeks ago was admitted with complaints of abdominal pain, bilateral flank pain, and restlessness. Her initial workup was significant for hyponatremia and hypokalemia. On the 3rd day of admission, she developed acute hypoxemic respiratory failure which led to intubation. At that time, CTA Chest was not done but CT Chest revealed prominent mucous plugging with left side glass ground opacities, Ultrasound of lower extremities revealed right common femoral vein DVT which led to concerns that she may have suffered from Pulmonary Embolism and led to starting Heparin drip. On the 6th day of admission, she developed Acute Encephalopathy, MRI Brain revealed acute infarcts in bilateral cerebral cortices and cerebella, CT Angiogram Head showed acute subarachnoid hemorrhage in the high posterior right parietal lobe, stenosis of the right high cervical internal carotid artery, and irregular, the appearance of the arterial vasculature throughout and CT Angiogram Neck abrupt change in caliber of the right ICA, 1.5 cm distal to the bifurcation with markedly severe narrowing of the majority of the extracranial right ICA throughout its course. A cerebral Angiogram was done which showed diffuse tandem segments of tandem cervical and intracranial portions of the right internal carotid artery and she was given nitroglycerin was administered as a therapeutic intervention. Lumbar Puncture showed WBC 2, RBC 7, Protein 162, Glucose 64, VZV PCR was negative, CSF VZV IgG Antibody positive at 303 IV (>165 IV indicative of current or past infection). Serum VZV IgG Antibody was positive at >4000 IV. Infectious Diseases were consulted after Lumbar Puncture, they initially started Acyclovir but once the Serum VZV IgG Antibody came back much higher than Serum VZV IgG Antibody levels, their assessment was that VZV vasculitis is unlikely and Acyclovir was discontinued. Eventually, the case was discussed at Neuroradiology which led to us getting a repeat MRA Neck without contrast which showed a concentric T1 and T2 hyperintensity along with a small and irregular caliber right cervical ICA consistent with dissection. She eventually completed a 21‐day course of Nimodipine due to underlying Subarachnoid Hemorrhage. Methods : NA Results : NA Conclusions : Our case demonstrates how it can become difficult to ascertain the etiology of stroke in certain patients. Our patient presented with multiple non‐specific symptoms initially and it was later on due to her Acute Encephalopathy that her Strokes and Subarachnoid Hemorrhage were discovered. It is still difficult to pinpoint whether the cause of strokes was dissection or VZV infection. Lumbar Puncture remains an essential tool to complete work up on uncommon etiologies of stroke.

Abstract 1122‐000216: Evacuation of Bilateral Intracerebral Hemorrhages Using a Novel Disposable Surgiscopic System: A Case Report

Introduction : Patients presenting with intracerebral hemorrhage (ICH) face higher rates of morbidity and mortality than other stroke patients. Currently, these patients are managed by surgical intervention and decompression or medical management, depending on categorization of the hemorrhage. Simultaneous, multifocal hemorrhages are a rare presentation of ICH that portend a worse prognosis. Here we report the treatment of bilateral simultaneous ICHs in a young patient with diagnostic cerebral angiography, biopsy, and bilateral minimally invasive surgiscopic ICH evacuation in a single procedure. Methods : The patient was a young female who presented to an outside hospital after two days of progressively worsening headaches and vomiting. Her medical history was significant for systemic lupus erythematosus (SLE), hypertension, chronic migraines, and opioid use disorder. In the emergency department, her mental status deteriorated, and she was intubated. Computed tomography (CT) scan was performed and showed a right parietal 43.3 cc ICH and a left parietal 38.7 cc ICH. MR angiogram and venogram showed no evidence of vascular malformations but were suggestive of potential cerebral venous sinus thrombosis. Upon arrival, the patient remained intubated but was able to open her eyes, follow commands, and respond to stimulation. The patient was brought to the angiosuite for diagnostic cerebral angiography which revealed diffuse intermittent arterial narrowing suggestive of vasculitis and patent venous sinuses. The patient was then positioned in the prone position and bilateral parietal 1.5 cm craniectomies were performed. Surgiscopic evacuation was performed sequentially using stereotactic navigation to access and evacuate each clot. A right parietal brain biopsy was performed at the minimally invasive cortical access point. Results : Active bleeding was encountered in both hematoma sites and was treated with a combination of irrigation and monopolar cautery transmitted through the Aurora Evacuator. After complete evacuation of the hematomas on both sides, an intraoperative conebeam CT was performed, demonstrating good right‐sided evacuation and resident left‐sided hematoma. Additional evacuation was performed on the left side and repeat conebeam CT demonstrated good bilateral evacuation. CT head on post operative day 1 showed 97.7% right‐sided evacuation and 81.5% left‐sided evacuation. The patient was treated with steroids for presumed vasculitis given the angiographic findings, which was later supported by the results of the brain biopsy. The patient made a good recovery and was discharged from the hospital alert and oriented, with CN II‐XII grossly intact, no focal deficits, and 5/5 strength in all extremities. Conclusions : Minimally invasive ICH evacuation can be performed in the angiosuite for ICH‐associated with vasculitis and even multifocal ICH when appropriate. Performing the procedure in the angiosuite permits completion of the diagnostic cerebral angiogram, brain biopsy, and hematoma evacuation at the same time, accelerating time to treatment for a patient with severe, symptomatic vasculitis.

Abstract 1122‐000138: De Novo Intracranial Stenosis after Mechanical Thrombectomy with Stent Retrievers

Introduction : Increased vascular damage with the use of stent‐retrievers (SR) has been shown on histopathological analysis of the vascular tissue immediately after mechanical thrombectomy (MT) in animal models. We hypothesized that intraoperative endovascular damage‐intimal injury could result in fibrosis and de novo vascular stenosis (dnVS). The purpose of the study is to identify de novo or worsening intracranial stenosis (wICS) of the treated vessel(s) on patients who underwent MT for the treatment of acute ischemic stroke with SR, on follow‐up vascular imaging (FVI). Methods : This was a retrospective chart review. Patients who underwent MT with SR at two centers from January 2015‐December 2020, who had FVI (CTA, MRA or cerebral angiogram) were included. Patient characteristics, procedural details, timing for FVI and clinical outcomes were collected. Two neuroradiologists reviewed baseline angiograms and FVI to assess for the presence of dnVS or wICS, and graded each stenosis and collateral scores (CS), when stenosis was present. CS were calculated using the multiphase CT angiography collateral score (mCTA). Fischer exact test and Mann‐Whitney U test were used to assess for differences in categorical and continuous variables, respectively. Statistical analysis was performed using SPSS 28.0 (IBM Corp.). Results : Forty‐six patients within this cohort had FVI with 9 patients developing dnVS or wICS in the follow‐up period (19.6%) with a median follow‐up of 113 days. Five of these patients demonstrated a complete occlusion of the target vessel on FVI. Of the remaining 4 patients, mean degree of stenosis was 55%. Only 2 of these patients had underlying stenosis on baseline post‐treatment angiogram: one with 44% stenosis which progressed to 95% in 2 months. Another with mild stenosis that progressed to complete occlusion in 50 days. Adequate revascularization, defined as TICI score >2b was achieved in 88.8% of patients with dnVS or wICS, and in 89.2% of patients with stable FVI. No significant differences were observed in baseline demographics, NIHSS score at presentation or initial ASPECTS. Median number of passes was identical between patients who developed dnVS or wICS (median 1, IQR [1, 2], p = 0.683). Mean CS for dnVS or wICS was 3. No significant differences were observed in discharge or follow‐up NIHSS scores, mRS, mortality, or recurrent stroke or TIA between the two cohorts. Conclusions : MT with SR can be associated with dnVS or wICS in some patients. The number of passes with SR did not seem to have an impact on this. Patients with dnVS or wICS did not have a higher incidence of recurrent stroke or TIA. This could be due to the development of new collaterals in this population. Our study is limited by a small cohort, however, larger studies might be challenging as standardized radiological follow up of these patients has not been implemented.

Abstract 1122‐000165: Endovascular Intervention for a Thrombotic Adverse Event During Andexanet Alfa Infusion

Introduction : Andexanet alfa is the only specific reversal agent for factor Xa inhibitors and received FDA approval in 2018. Here we report an early infusion adverse event in a patient with acute intraventricular hemorrhage (IVH) that received Andexanet alfa, with an unfavorable outcome. Methods : A 73‐year‐old male presented to our emergency department (ED) after he developed sudden onset of severe headache without other associated neurological symptoms. An outpatient brain MRI showed IVH, that remained stable in size (2.4 cm3) on a follow‐up head CT performed in our ED. CT angiogram showed a 60% stenosis of the left supraclinoid internal carotid artery. The patient was taking apixaban 5 mg twice daily for atrial fibrillation (last dose 5.5 hours prior to presentation). Results : The anticoagulation was reversed with Andexanet alfa, 400 mg bolus given at 18:30, followed by 480 mg infusion over 2 hours started at 19:00 (12 hours from last apixaban dose). At 19:00, he developed left middle cerebral artery (MCA) ischemic stroke symptoms (global aphasia) that resolved with head‐of‐the‐bed flattening. CT perfusion demonstrated left ICA territory mismatch (342 ml) and 76 ml core. Shortly after CT perfusion, the patient developed a persistent complete left MCA stroke syndrome with NIH stroke scale (NIHSS) score 23. Decision was made to perform emergent cerebral angiogram which demonstrated a large, fresh thrombus in the left cervical ICA. Thrombectomy was successful with TICI score 2B. Patient’s neurological status initially improved. However, despite this intervention, patient developed a large territory infarct. As neurologic status remained poor, family withdrew care and patient died. Conclusions : ANNEXA‐A and ANNEXA‐R were parallel trials of Andexanet alfa for factor Xa inhibitor reversal that demonstrated a transient increase in prothrombotic factors post Andexanet alfa infusion. Neither of these phase 3 trials nor the previous phase 2 trials reported a clinical thrombotic event very early during the infusion. The ANNEXA‐4 trial (Phase 3) enrolled subjects with active major bleeding on a factor Xa inhibitor and 10% developed a thrombotic event during the 30‐day follow‐up period. 41% of the thrombotic complications were acute ischemic stroke (AIS), 35% (5 patients) experienced an AIS in the first six days post‐administration and the earliest reported thrombotic event occurred day 1 post infusion. Our case report illustrates an early cerebrovascular thrombotic event with dismal outcome despite timely and effective mechanical reperfusion therapy, which could be due to vessel re‐obstruction in setting of a hypercoagulable state. We aim to make vascular neurologists, neurointensivists and neurosurgeons aware of this possible occurrence when reversing patients with factor Xa‐related intracranial hemorrhages.

Abstract 1122‐000050: Arterial Steal in AVM: An Etiology of Ischemic Stroke

Introduction : Arteriovenous malformations (AVM) are rare congenital malformations in the brain, often presenting with cerebral hemorrhage. Unruptured AVMs usually remain asymptomatic, or they can present with headache, seizure, or focal neurological deficits. “Arterial steal” is one of the mechanisms which can lead to focal neurological deficits. The idea of vascular steal through high flow shunting within brain AVMs is not a new concept. There is, however, debate about whether the vascular steal phenomenon indeed exists empirically. In a study focused on vascular reserve in patients with cerebral AVMs (utilizing acetazolamide augmentation and perfusion CT methods), decreased hemodynamic reserve was noted in 27% of parenchymal regions of interest close to the AVM and in 17% of parenchymal regions of interest far from the AVM. Other imaging modalities have shown abnormal blood regulation around AVM however there exists a level of discordance between various modalities which questions whether vascular steal exists in vivo. We present an ischemic stroke caused by “arterial steal” phenomenon. Methods : Case report Results : 63‐year‐old male with past medical history of seizure, hypertension presented with confusion and dysarthria for 3 weeks. On exam he was found to have right upper quadrantanopia. CT head without contrast and MRI of brain revealed an evolving infarct in the left posterior cerebral artery (PCA) territory. CT angiogram showed possible occlusion in the left PCA P2 segment which correlated to the previously described stroke and in addition showed evidence of left thalamic AVM. Evaluation for cardioembolic or atheroembolic sources was unrevealing. A diagnostic cerebral angiogram showed a 1.3 mm AVM fed through anterior choroidal branches as well as posterior choroidal branches through left posterior communicating artery. There was delayed filling in the left PCA territory likely due to steal phenomenon which might be the etiology of the stroke. Conclusions : In our case, as demonstrated on angiogram, vascular steal phenomenon through high flow shunting of AVM is the likely explanation for the ischemic stroke.

Abstract 1122‐000124: Dural Arteriovenous Fistula and Implications in Aneurysmal Genesis

Introduction : There is a reported association of cerebral arteriovenous malformations and aneurysms, however, data regarding patients presenting with dural arteriovenous fistulas (dAVF) and aneurysms is limited. Here, we present a patient who was incidentally diagnosed with 2 aneurysms in addition to a dAVF; and her treatment course. Previous to her diagnosis, she denied any and all symptomatology that would prompt further evaluation. Methods : Case description: 60‐year‐old female with history of hypertension, hypothyroidism and gastroesophageal reflux disease who initially presented to an outside hospital after a motor vehicle collision in 2016, at that time she reports being diagnosed with multiple aneurysms; but was lost to follow up. In 2020 she was referred to interventional neuroradiology and underwent diagnostic digital cerebral angiogram. Which reported a 13 × 12 × 13.3 mm left para‐ophthalmic internal carotid artery (ICA) aneurysm with a 7 mm neck. A 5.7 × 7.7 × 6.1 mm basilar tip artery aneurysm with a 5.6 mm neck and a right Cognard type four occipital dAVF, with feeding vessels from the right posterior cerebral artery and right occipital artery and anterograde drainage to the dural sinuses. From the time of diagnosis to the initiation of interventions, patient denied any concerning symptomatology. Treatment was initiated 4 months after diagnostic angiogram. She received 5 days of Dual Antiplatelet therapy (DAPT) with aspirin and Plavix previous to the deployment of a woven endobridge device (WEB™ 8‐3mm) into the basilar tip aneurysm; as this was felt to be the aneurysm with highest probability of rupture. Post‐operative course was unremarkable and DAPT was discontinued. Three months after WEB™ deployment, the patient underwent embolization of the right occipital dAVF with a liquid embolic agent (onyx™). Post operatively, she developed decreased peripheral vision in her left eye, though the rest of her hospitalization was unremarkable. 3 months after embolization, she underwent left para‐ophthalmic artery aneurysm flow diversion with a pipeline™ (4‐18mm) flow diverter, with an uncomplicated admission. She was subsequently evaluated by neuro‐ophthalmology who has reported a stable peripheral left eye left inferior quadrantic defect along with a supertemporal defect in her right eye. Results : Discussion: Interestingly, the patient presented 2 aneurysms, one in the anterior circulation and the most concerning, located in the posterior circulation. One could draw conclusions that the dAVF was associated with the basilar aneurysm. As dAVFs are acquired lesions, it is feasible to assume that there may be an association between both types of lesions, perhaps due to flow or pressure being exerted on weakened vessel walls, thus leading to aneurysmal formation. Conclusions : Conclusion: Because a potential for implication in the flow dynamics of the dAVF in aneurysmal formation. We have opted to use computational fluid dynamics to analyze said flow within the dAVF to better understand the causal relationship between aneurysms and dural fistulae. In the long run research into genesis of aneurysms secondary to coexisting vascular lesions could further elucidate the mechanisms by which aneurysms develop.

Abstract 1122‐000198: Failure of Tenecteplase in Maintaining Collateral Circulation in Large Vessel Occlusion Strokes.

Introduction : Acute administration of alteplase with collateral patency has been systematically evaluated in acute ischemic stroke (AIS) patients. Large studies evaluating alteplase demonstrate a significant association of successful recanalization (TICI score) and good clinical outcome (mRS) with ASITN/SIR collateral grade greater than 2. However there is paucity of data looking at the association between IV tenecteplase (TNK) and acute collateralization. Our objective was to investigate early TNK use association for the degree of collateralization in subjects with AIS secondary to large vessel occlusion (LVO). Methods : Collateralization was assessed on digital subtraction angiography using the American Society of Intervention and Therapeutic Neuroradiology/Society of Interventional Radiology (ASTIN/SIR) scale. Grades were defined by the following: 0 no collaterals to ischemic region; 1 slow collaterals peripherally; 2 rapid collaterals peripherally; 3 slow collaterals within ischemic region; 4 complete retrograde perfusion to ischemic region. Subjects with LVO undergoing mechanical thrombectomy status post TNK as part of the pilot early clinical use of TNK within 4.5 hours of last known well were assigned a grade. Mean ASITN/SIR collateral grade was determined. Spearman’s rho was used to measure association of collateral grade with thrombolysis in cerebral infarction (TICI) score. Patients with TNK‐associated recanalization at time of cerebral angiogram were excluded from study. Social Science Statistics was used for data analysis. Results : From October 2020 to April 2021, 16 subjects (6 females; age, 63.25 95% CI [54.9207, 71.5793]) received TNK and underwent mechanical thrombectomy. From those subjects, 25 % (n = 4) had IV TNK‐associated recanalization with normalization of collateral blood flow and were excluded. Of the rest (n = 12, 75%) had a mean ASITN/SIR collateral grade of 1.08 (95% CI [0.5762, 1.5838]). Association between collateral grade and final TICI score was not statistically significant (rs = ‐0.33576, p = 0.28598) suggesting inability of TNK to result in/maintain a robust collateral flow. Conclusions : Poor correlation of collateral grade and final TICI score may have implications of faster progression in patients with ischemic stroke receiving TNK in the setting of LVO if immediate recanalization is not achieved. Larger prospective studies are needed to evaluate the effect of TNK on collateralization when compared to Alteplase.