Parham Yashar

Endovascular management of spinal dural arteriovenous fistulas. A review.

OBJECT Spinal dural arteriovenous fistulas (DAVFs) are the most common spinal vascular malformations and can be a significant cause of myelopathy, yet remain inefficiently diagnosed lesions. Over the last several decades, the treatment of spinal DAVFs has improved tremendously due to improvements in neuroimaging, microsurgical, and endovascular techniques. The aim of this paper was to review the existing literature regarding the clinical characteristics, classification, and endovascular management of spinal DAVFs. METHODS A search of the PubMed database from the National Library of Medicine and reference lists of all relevant articles was conducted to identify all studies pertaining to spinal DAVFs, spinal dural fistulas, and spinal vascular malformations, with particular attention to endovascular management and outcomes. RESULTS The ability to definitively treat spinal DAVFs using endovascular embolization has significantly improved over the last several decades. Overall rates of definitive embolization of spinal DAVFs have ranged between 25 and 100%, depending in part on the embolic agent used and the use of variable stiffness microcatheters. The majority of recent studies in which N-butyl cyanoacrylate or other liquid embolic agents were used have reported success rates of 70-90%. Surgical treatment remains the definitive option in cases of failed embolization, repeated recanalization, or lesions not amenable to embolization. Clinical outcomes have been comparable to surgical treatment when the fistula and draining vein remain persistently occluded. Improvements in gait and motor function are more likely following successful treatment, whereas micturition symptoms are less likely to improve. CONCLUSIONS Endovascular embolization is an increasingly effective therapy in the treatment of spinal DAVFs, and can be used as a definitive intervention in the majority of patients that undergo modern endovascular intervention. A multidisciplinary approach to the treatment of these lesions is required, as surgery is required for refractory cases or those not amenable to embolization. Newer embolic agents, such as Onyx, hold significant promise for future therapy, yet long-term follow-up studies are required.

A study of CrNx thin films by X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy has been employed to study the electronic structure of CrNx thin films. The films have been deposited with varying concentration of nitrogen on a stainless steel substrate by a d. c. magnetron sputtering technique. The Cr 2p, Cr LMM Auger, N 1s, and N KLL Auger regions were investigated using Mg Kα radiation. Results indicate changes in the electronic structure of Cr and N in these films. The Auger parameter shows an increasing trend for Cr and a decreasing trend for N. This has been interpreted as increasing charge transfer from Cr to N with increasing content of nitrogen. The full width at half maximum observed for Cr 2p3/2 peak shows an increasing trend with the nitrogen concentration. The density of states at the Fermi level estimated from the asymmetry index of the Cr 2p3/2 peak is larger than that for elemental chromium. However, in the films a decreasing trend is observed for the density of states with increasing nitrogen content. The chemical shift for the Cr 2p3/2 peak shows a decreasing trend while that for the N 1s peak shows an increasing trend. Using the Auger parameter as an approximation for the relaxation shift, the trend in the contribution due to configuration changes in these films has been estimated. The configuration change (hybridization effects) is observed to increase with the increase in the nitrogen content. These changes are interpreted as increasing hybridization of the Cr 3d and 4sp orbitals, with N 2p orbitals as the concentration of nitrogen increases. The observations are corroborated by results on the stoichiometric compound CrN by other studies.

Is Bridging with Intravenous Thrombolysis of Any Benefit in Endovascular Therapy for Acute Ischemic Stroke

OBJECTIVE Large vessel occlusions with heavy clot burden are less likely to improve with intravenous (IV) thrombolysis alone. The purpose of this study was to show whether a combination of IV thrombolysis and endovascular therapy was superior to endovascular treatment alone. METHODS Data for 104 patients with acute large artery occlusion treated between 2005 and 2010 were reviewed. Forty-two received endovascular therapy in combination with IV thrombolysis (bridging group), and 62 received endovascular therapy only. Clinical outcome, mortality rate, and symptomatic intracranial hemorrhage (sICH) rate were compared between the two groups. RESULTS The two groups had similar demographic and vascular risk factor distribution, as well as National Institutes of Health Stroke Scale score on admission (mean±SD: 14.8±4.7 and 16.0±5.3; P=0.23). No difference was found in Thrombolysis in Myocardial Infarction recanalization rates (score of 2 or 3) after combined or endovascular therapy alone (83.33% and 79.03%; P=0.585). Favorable outcome, defined as a modified Rankin Scale score of <2 at 90 days, also did not differ between the bridging group and the endovascular-only group (37.5% and 32.76%; P=0.643). There was no difference in mortality rate (19.04% and 29.03%; P=0.5618) and sICH rate (11.9% and 9.68%; P=0.734). A significant difference was found in mean time from symptom onset to treatment in the bridging group and the endovascular-only group (227±88 min vs. 125±40 min; P<0.0001). CONCLUSION Combining IV thrombolysis with endovascular therapy resulted in similar outcome, revascularization, sICH, and mortality rates compared with endovascular therapy alone. Prospective clinical studies comparing both treatment strategies in acute ischemic stroke are warranted.

Cerebral arteriovenous malformations: issues of the interplay between stereotactic radiosurgery and endovascular surgical therapy.

Intracranial arteriovenous malformations (AVMs) are congenital lesions frequently diagnosed as a result of hemorrhage or other neurological symptoms. Prevention of such devastating neurological injury has promoted a variety of treatment strategies. The rich history of multimodal therapy in the treatment of AVMs includes microsurgery, endovascular embolization, and stereotactic radiosurgery (SRS). This article reviews the biology and natural history of AVMs, as well as their treatment with both SRS and endovascular neurosurgery. It considers various paradigms and goals of endovascular treatment, along with relevant issues such as the features of an AVM to be targeted. Issues of the interplay between SRS and endovascular neurosurgery include the compartments of an embolized AVM to contain within the radiosurgery plan, the radioprotective and radiosensitizing effects of the embolic agent, the durability of embolization, and the sequencing of embolization with respect to the radiosurgical treatment. Published literature on these topics is sparse, and the flimsiness of the data offers limited guidance.

Intracranial Chondrosarcoma: A Case Report and Review of the Literature

AbstractObjective and importance: Chondrosarcomas rarely occur intracranially away from the skull base. We present a case of a supratentorial dural-based, low-grade classic chondrosarcoma and emphasize salient imaging findings that assist in its diagnosis. Clinical presentation: A 23-year-old female presented with new onset seizures. Multiple radiographic imaging studies identified a large left frontal mass with radiological findings that suggested the correct diagnosis. Intervention: The patient underwent a left frontal craniotomy and gross total resection of the lesion and associated dura. Conclusion: Intracranial chondrosarcomas away from the skull based are extremely rare malignancies. As with other extra-axial masses, they often grow to a relatively large size before generating symptoms. Careful analysis of CT, MR, and angiographic imaging characteristics should suggest the correct diagnosis.

Use of the Microangiographic Fluoroscope for Coiling of Intracranial Aneurysms

BACKGROUND Neurointervention is an ever-evolving specialty with tools including microcatheters, microwires, and coils that allow treatment of pathological conditions in increasingly smaller intracranial arteries, requiring increasing accuracy. As endovascular tools evolve, so too should the imaging. OBJECTIVE To detail the use of microangiography performed with a novel fluoroscope during coiling of intracranial aneurysms in 2 separate patients and discuss the benefits and potential limitations of the technology. METHODS The microangiographic fluoroscope (MAF) is an ultra high-resolution x-ray detector with superior resolution over a small field of view. The MAF can be incorporated into a standard angiographic C-arm system for use during endovascular procedures. RESULTS The MAF was useful for improved visualization during endovascular coiling of 2 unruptured intracranial aneurysms, without adding significant time to the procedure. No significant residual aneurysm filling was identified post-coiling, and no complications occurred. CONCLUSION The MAF is a high-resolution detector developed for use in neurointerventional cases in which superior image quality over a small field of view is required. It has been used with success for coiling of 2 unruptured aneurysms at our institution. It shows promise as an important tool in improving the accuracy with which neurointerventionists can perform certain intracranial procedures. ABBREVIATIONS AP: anteroposterior CT: computed tomography CTA: CT angiography DSA: digital subtraction angiography FOV: field of view ICA: internal carotid artery MAF: microangiographic fluoroscope

Endovascular coil embolization of a very small ruptured aneurysm using a novel microangiographic technique: technical note

Endovascular treatment of very small aneurysms is technically difficult, although recent advances with coils, microcatheters and adjunctive techniques such as balloon- or stent-assisted coiling have improved the outcomes. The microangiographic fluoroscope (MAF) is a new high-resolution x-ray detector developed for neurointerventional procedures in which superior resolution is required within a small field of view. We report the successful coil embolization of a very small ruptured anterior communicating artery aneurysm using the MAF technique. The use of the MAF facilitated the precision of the coiling procedure and was helpful in preventing catheter- and coil-related intraprocedural complications.

Horizontal deployment of an intracranial stent via an antegrade approach for coil embolization of a basilar apex aneurysm: technical note

The treatment of basilar apex aneurysms has progressively become more minimalistic in nature. Although initial coil embolizations were geared towards those aneurysms with a favorable neck to dome ratio, wide necked aneurysms have also been increasingly treated by the endovascular route. Several techniques have been described in the stent assisted coiling of basilar apex aneurysms, including the Y stent formation, waffle cone technique and horizontal stenting. Thus far, horizontal stenting has required access from a retrograde approach—namely, the posterior communicating artery. The authors describe a novel antegrade technique, through the basilar artery, for the deployment of a Neuroform-EZ stent (Boston Scientific, Natick, Massachusetts, USA) in a horizontal configuration across the neck of a basilar apex aneurysm. This approach allowed for the complete coil embolization of a wide necked basilar apex aneurysm.

HoxD10 gene delivery using adenovirus/adeno-associate hybrid virus inhibits the proliferation and tumorigenicity of GH4 pituitary lactotrope tumor cells

Prolactinoma is one of the most common types of pituitary adenoma. It has been reported that a variety of growth factors and cytokines regulating cell growth and angiogenesis play an important role in the growth of prolactinoma. HoxD10 has been shown to impair endothelial cell migration, block angiogenesis, and maintain a differentiated phenotype of cells. We investigated whether HoxD10 gene delivery could inhibit the growth of prolactinoma. Rat GH4 lactotrope tumor cells were infected with adenovirus/adeno-associated virus (Ad/AAV) hybrid vectors carrying the mouse HoxD10 gene (Hyb-HoxD10) or the beta-galactosidase gene (Hyb-Gal). Hyb-HoxD10 expression inhibited GH4 cell proliferation in vitro. The expression of FGF-2 and cyclin D2 was inhibited in GH4 cells infected with Hyb-HoxD10. GH4 cells transduced with Hyb-HoxD10 did not form tumors in nude mice. These results indicate that the delivery of HoxD10 could potentially inhibit the growth of PRL-secreting tumors. This approach may be a useful tool for targeted therapy of prolactinoma and other neoplasms.

Posterior Inferior Cerebellar Artery to Posterior Inferior Cerebellar Artery In Situ Bypass for the Treatment of Bow Hunter's-Type Dynamic Ischemia in Holovertebral Dissection

BACKGROUND Bow hunters syndrome is a rare cause of vertebrobasilar insufficiency arising from mechanical compression of the vertebral artery (VA) during rotation of the head. Surgical treatment usually involves direct decompression of the VA at the site of compression. We describe what is to our knowledge the first reported case of a posterior inferior cerebellar artery (PICA)-to-PICA in situ bypass for treatment of Bow hunters-type ischemia in a patient with a VA dissection. CASE DESCRIPTION The patient was a 41-year-old man who developed disabling symptoms of vertebrobasilar insufficiency after trauma when he rotated his head to the right. Dynamic angiography demonstrated a chronic dissection and stasis of flow in the right VA when his head was rotated to the right, with no obvious site of focal compression. The right VA ended in the PICA and the left VA was of good caliber. A single-photon emission computed tomography study with acetazolamide challenge confirmed brainstem ischemia and poor cerebrovascular reserve. He ultimately underwent a PICA-to-PICA in situ bypass to revascularize his right PICA territory with complete symptom resolution. CONCLUSIONS The PICA-to-PICA in situ bypass is a useful option in the treatment of Bow hunters-type ischemia in the absence of focal structural compression of the VA or VA stenosis.