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.

Normalization of Peri-Arteriovenous Malformation Hemodynamics Prior to Direct Microsurgery: 2-Dimensional Operative Video

Arteriovenous malformations (AVMs) are highly complex vascular lesions characterized by abnormal connections between arteries and an intervening nidus. Definitive and safe treatment of AVMs may require the combination of multiple treatment modalities to address the various complex features of the AVM.1 Endovascular embolization can be used as an adjuvant to surgery in order to control deep feeders, reduce flow, and address high-risk features such as aneurysms. In addition, by progressively reducing the AVM flow, staged embolization can lead to normalization of peri-AVM hemodynamics and therefore may decrease the risk of postresection hemorrhage.2,3 In this operative video, we present a case of a 41-yr-old female who presented with progressively worsening left-sided hemiparesis. Magnetic resonance imaging (MRI) and angiography revealed a complex right fronto-parietal AVM with significant associated edema, likely due to the vascular steal phenomenon. The area of edema, which included the motor cortex, was thought to be at high risk for postoperative hemorrhage from normal perfusion pressure breakthrough. We therefore decided to proceed with staged presurgical embolization to gradually normalize the perilesional hemodynamics, and therefore possibly reduce the risk of postoperative morbidity. The patient underwent 3 embolization sessions at 6-wk intervals. An MRI after the last embolization showed near-complete resolution of the fluid-attenuated inversion-recovery (FLAIR) signal around the AVM. Microsurgical resection was performed on the day after the last embolization. The patient tolerated the procedure well and was discharged at her neurological baseline with mild contralateral hemiparesis, which has continued to improve at follow-up. Postoperative angiography showed complete resection of the AVM. The patient consented to the procedure as shown in this operative video and gave informed written consent for use of her images in publication.

Chronic Ischemic Monomelic Neuropathy after Arteriovenous Fistula Creation: A Unique Presentation of Vascular Steal

We discuss a case of a 58 year old male who presented for left upper extremity steal syndrome including ischemic monomelic neuropathy (IMN) 1.5 months after arteriovenous fistula creation. He presented after three surgical attempts to salvage his fistula with rest pain, complete loss of function with contracture of the 4th and 5th digits, and loss of sensation in the ulnar distribution for more than three weeks. At our institution, he underwent surgical ligation of the distal fistula and creation of a new fistula proximally, resulting in complete resolution of his vascular steal symptoms almost immediately despite the chronicity prior to surgical presentation. Our patient provides a unique perspective regarding dialysis access salvage versus patient quality of life. The patients’ functional status and pain levels should take precedence over salvage of an arteriovenous access site, and early ligation of the access should be completed prior to chronic IMN development. However, if a patient presents late along the IMN course, we recommend strong consideration of access ligation in order to attempt to regain the full neurovascular function of the extremity as we experienced in our patient.

Sirenomelia with Potter syndrome: a case report and review of literature

Sirenomelia or mermaid syndrome is a rare congenital anomaly characterized by variable degree of fusion of lower extremities. Awareness to this rare condition is important for prenatal diagnosis and prognosticating the fetus. The exact etiopathogenesis is still an area of research. Two pathogenic hypotheses are the vascular steal hypothesis and the defective blastogenesis hypothesis with exceptions reported in literature.

Cervical 7-Thoracic 3 Laminoplasty for Resection of Arteriovenous Malformation: 2-Dimensional Operative Video

Symptomatic spinal arteriovenous malformations (AVMs) are most frequently associated with hypoperfusion of the spinal cord, either from venous congestion or vascular steal, and are less frequently associated with hemorrhage. This patient had a large cervicothoracic spinal AVM and presented with right hemibody sensory deficit with intact motor function. The AVM had significant preoperative mass effect on the dorsal spinal cord with cord signal change. Preoperative digital subtraction angiography demonstrated a left supreme intercostal feeding artery and left thyrocervical feeding artery, which was embolized preoperatively. A laminoplasty was performed from cervical 7 to thoracic 3 to allow for adequate visualization. The lesion demonstrated an intradural extramedullary presence, which made preservation of the pia mater paramount during the resection. The AVM was disconnected and removed in its entirety as determined by operative visualization and postoperative imaging. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Middle meningeal artery occlusion for intra-arterial chemotherapy of retinoblastoma

We report the intentional occlusion of the middle meningeal artery arising from the lacrimal artery, a novel technique to improve drug delivery in a 14-month-old boy with a history of right sporadic unilateral cavitary retinoblastoma group D. The patient was referred to our institution for intra-arterial chemotherapy after two systemic chemotherapy treatments. The digital subtraction angiography showed a large middle meningeal artery arising from the right lacrimal artery and decrease choroidal enhancement thus decreased flow to the tumor. The ophthalmological examination after the first intra-arterial chemotherapy observed no tumor regression. Assuming a vascular steal, in the second intra-arterial chemotherapy session, the origin of the middle meningeal artery was occluded. Following this treatment, a significant response was observed at ophthalmological follow up. In the presented case, the efficacy of intra-arterial chemotherapy was improved after occlusion of a meningeal branch arising from the lacrimal artery, which was responsible for the vascular steal.