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R. L. Patrick Rhoten, Youssef G. Comair, Daniel Shedid, Douglas Chyatte and Michael S. Simonson

✓ Cerebrovascular arteriovenous malformations (AVMs) display abnormal vascular development and dysautoregulation of blood flow. Genetic mechanisms that contribute to the pathogenesis and phenotype of cerebral AVMs are unknown. As a first step in understanding the pathophysiology of AVMs, the authors investigated the hypothesis that endothelial dysfunction—specifically, deregulation of endothelin-1 (ET-1) secretion—contributes to the abnormal vascular phenotype and the lack of hemodynamic autoregulation elaborated by these lesions. Endothelin-1 peptide and preproendothelin-1 (ppET1) messenger RNA were not detected in the intranidal vasculature of all 17 patients with AVMs studied, but were prominently expressed in human control subjects with normal cerebrovasculature (p < 0.01). Although AVM vasculature lacked ET-1, its expression was prominent in vasculature distant from these lesions, suggesting local repression of the ppET-1 gene. Local repression of ET-1 was specific to AVMs; ET-1 in vascular malformations of patients with Sturge—Weber disease was actually elevated compared to normal controls (p < 0.01). Repression of the ppET-1 gene was an intrinsic phenotype of AVM endothelial cells and was not due to factors in the AVM microenvironment. The authors also showed that ETA receptor expression was low in AVM vasculature compared to normal controls. Together, these results demonstrate that the ppET-1 gene is locally repressed in AVM lesions and suggest a role for abnormal ppET-1 gene regulation in the pathogenesis and clinical sequelae of cerebral AVMs.

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David Dornbos III, Constantine L. Karras, Nicole Wenger, Blake Priddy, Patrick Youssef, Shahid M. Nimjee and Ciarán J. Powers


The utilization of the Pipeline embolization device (PED) has increased significantly since its inception and original approval for use in large, broad-necked aneurysms of the internal carotid artery. While microsurgical clipping and advances in endovascular techniques have improved overall efficacy in achieving complete occlusion, recurrences still occur, and the best modality for retreatment remains controversial. Despite its efficacy in this setting, the role of PED utilization in the setting of recurrent aneurysms has not yet been well defined. This study was designed to assess the safety and efficacy of PED in the recurrence of previously treated aneurysms.


The authors reviewed a total of 13 cases in which patients underwent secondary placement of a PED for aneurysm recurrence following prior treatment with another modality. The PEDs were used to treat aneurysm recurrence or residual following endovascular coiling in 7 cases, flow diversion in 2, and microsurgical clipping in 4. The mean time between initial treatment and retreatment with a PED was 28.1 months, 12 months, and 88.7 months, respectively. Clinical outcomes, including complications and modified Rankin Scale (mRS) scores, and angiographic evidence of complete occlusion were tabulated for each treatment group.


All PEDs were successfully placed without periprocedural complications. The rate of complete occlusion was 80% at 6 months after PED placement and 100% at 12 months in these patients who underwent PED placement following failed endovascular coiling; there were no adverse clinical sequelae at a mean follow-up of 26.1 months. In the 2 cases in which PEDs were placed for treatment of residual aneurysms following prior flow diversion, 1 patient demonstrated asymptomatic vessel occlusion at 6 months, and the other exhibited complete aneurysm occlusion at 12 months. In patients with aneurysm recurrence following prior microsurgical clipping, the rate of complete occlusion was 100% at 6 and 12 months, with no adverse sequelae noted at a mean clinical follow-up of 27.7 months.


The treatment of recurrent aneurysms with the PED following previous endovascular coiling, flow diversion, or microsurgical clipping is associated with a high rate of complete occlusion and minimal morbidity.

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Melanie D. King, Melissa D. Laird, Sangeetha Sukumari Ramesh, Patrick Youssef, Basheer Shakir, John R. Vender, Cargill H. Alleyne Jr. and Krishnan M. Dhandapani

Subarachnoid hemorrhage (SAH) is a devastating neurological injury associated with significant patient morbidity and death. Since the first demonstration of cerebral vasospasm nearly 60 years ago, the preponderance of research has focused on strategies to limit arterial narrowing and delayed cerebral ischemia following SAH. However, recent clinical and preclinical data indicate a functional dissociation between cerebral vasospasm and neurological outcome, signaling the need for a paradigm shift in the study of brain injury following SAH. Early brain injury may contribute to poor outcome and early death following SAH. However, elucidation of the complex cellular mechanisms underlying early brain injury remains a major challenge. The advent of modern neuroproteomics has rapidly advanced scientific discovery by allowing proteome-wide screening in an objective, nonbiased manner, providing novel mechanisms of brain physiology and injury. In the context of neurosurgery, proteomic analysis of patient-derived CSF will permit the identification of biomarkers and/or novel drug targets that may not be intuitively linked with any particular disease. In the present report, the authors discuss the utility of neuroproteomics with a focus on the roles for this technology in understanding SAH. The authors also provide data from our laboratory that identifies high-mobility group box protein-1 as a potential biomarker of neurological outcome following SAH in humans.