Spinal dural arteriovenous fistulas (SDAVFs) are the most common type of spinal arteriovenous malformations. Type 1 spinal arteriovenous malformations are defined by the presence of radiculomeningeal feeders that drain into intradural veins. Patients with these lesions frequently present with chronic myelopathy, which is most often caused by venous hypertension. The authors present the case of a 69-year-old man with acute paraparesis following a lumbar epidural injection, resulting from a previously undiagnosed SDAVF. The patient initially reported right lower-extremity weakness and paresthesias and was referred to an orthopedic practice. His pain and weakness were exacerbated with ambulation. Reevaluation at 4 months was remarkable for groin, mild low-back, and buttock pain. The patient received a right L5–S1 interlaminar epidural steroid injection and became acutely weak. He presented to the emergency department 3 hours after the injection. Once MRI of the lumbar and thoracic spine had been performed, the neurosurgery service was consulted, and it was decided to proceed with emergent spinal angiography with the intent to embolize the fistula. An emergent spinal angiogram was obtained, revealing 2 arterial pedicles emanating from the right T-5 and T-6 radicular arteries. Transarterial embolization was thought to be the most rapid way to potentially obliterate the fistula. The patient exhibited immediate improvement in neurological function, and by 6 hours postprocedure, his neurological function was near normal. He was ambulatory and released to home 3 days after the embolization procedure.
T. Adam Oliver, Michael Sorensen and Adam S. Arthur
Ganesh Rao, Adam S. Arthur and Ronald I. Apfelbaum
✓ Fractures of the craniocervical junction are common in victims of high-speed motor vehicle accidents; indeed, injury to this area is often fatal. The authors present the unusual case of a young woman who sustained a circumferential fracture of the craniocervical junction. Despite significant trauma to this area, she suffered remarkably minor neurological impairment and made an excellent recovery. Her injuries, treatment, and outcome, as well as a review of the literature with regard to injuries at the craniocervical junction, are discussed.
Adam S. Arthur, Philipp Taussky, Min S. Park, Michael F. Stiefel and Robert H. Rosenwasser
Bernhard Sutter, Satoshi Suzuki, Adam S. Arthur, Neal F. Kassell and Kevin S. Lee
✓ Calcitonin gene—related peptide (CGRP) is a potent vasodilator and a primary signaling molecule in neurovascular communication. In the present study, the authors examined cerebrovascular responses to CGRP and its related second messenger systems during cerebral vasospasm induced by subarachnoid hemorrhage (SAH). Tension measurements were performed in vitro on ring strips of basilar arteries obtained from rabbits subjected to artificial SAH and from control (non-SAH) animals. In vessels from SAH animals, which were preconstricted with serotonin, the vasorelaxant response to CGRP was attenuated. Because it has been suggested that vasodilation elicited by CGRP is mediated by cyclic 3′,5′-adenosine monophosphate (cAMP) and/or cyclic 3′,5′-guanosine monophosphate (cGMP), the vascular effects of directly activating these second messenger systems were also examined. The relaxant effect of forskolin, which activates adenylate cyclase directly, was slightly enhanced after SAH. In contrast, the relaxant effect of nitroglycerin (GTN), which activates soluble guanylate cyclase directly, was unchanged after SAH.
The attenuation of CGRP-induced vasorelaxation could be the result of a modification in its ability to stimulate the production of second messengers. Experiments testing the capacity of CGRP to elevate cAMP levels showed no significant differences between vessels from non-SAH and SAH animals. Similarly, the resting levels of cAMP and the forskolin-induced elevations of cAMP did not differ between non-SAH and SAH animals. In contrast, cGMP levels were lower in resting and CGRP-treated vessels from SAH animals than in those from non-SAH animals. No significant differences in the levels of cGMP were observed between non-SAH and SAH vessels treated with GTN.
This study indicates that CGRP-induced vasodilation is attenuated during vasospasm in a rabbit model of SAH. The findings also demonstrate that vasodilatory responses mediated by cAMP and cGMP are intact, although the levels of cGMP in SAH vessels are reduced. Together, these observations suggest that an attenuation in the capacity of vessels to dilate in response to CGRP occurs during cerebral vasospasm, and this change in CGRP vasoactivity is a result of modifications prior to, or independent of, the elevation of cyclic nucleotide second messengers.
Vinodh T. Doss, Jason Weaver, Scott Didier and Adam S. Arthur
Aneurysmal bone cysts (ABCs) are destructive cystic lesions of the bone and are common in children. They are expansile in nature and, therefore, may become symptomatic. These have traditionally been treated surgically; but recently, endovascular embolization has shown promise as a stand-alone therapy. The authors describe a case of an ABC highlighting the effectiveness and efficiency of endovascular treatment. A 16-year-old boy was referred for a 4-month history of radiating back pain and urinary hesitancy. Findings from his neurological examination were normal, but he had problems ambulating because of pain. Magnetic resonance imaging and CT scanning showed a cystic mass in the sacrum; a biopsy was performed and diagnosis of ABC was confirmed. Treatment options were then discussed with the family.
The patient underwent 2 endovascular embolizations in approximately 1 month: Onyx 18 was involved in the first session, and N-butyl cyanoacrylate glue was used in the second session. After the first treatment, the patient experienced a dramatic decrease in pain and concomitant improvement in function. The patient went from being mildly symptomatic after the first treatment to completely asymptomatic after the second treatment. Clinical and radiographic follow-up obtained at 2, 6, and 18 months after initial treatment revealed the patient to be asymptomatic with progressive ossification.
Endovascular treatment can be effective in treating symptomatic cases of ABC in which surgery would carry significant risk. Selective arterial embolization can promote sclerosis and result in an immediate and significant decrease in pain.
Gregory J. Zipfel, David M. Hasan, Felipe C. Albuquerque and Adam S. Arthur
Over the past decade substantial advances in diagnostic imaging, classification, and understanding the natural history of intracranial dural arteriovenous fistula (dAVF) have been made. Paralleling these improvements in patient evaluation and risk assessment have been considerable innovations and refinements in the microsurgical and endovascular techniques by which appropriately selected patients with dAVF are treated. On the microsurgical front, minimally invasive surgical approaches with less soft tissue and bony disruption, along with enhanced tools for the intraoperative assessment of vascular anatomy and completeness of dAVF obliteration, are now commonly utilized. On the endovascular front, liquid embolic agents, balloons, and flow-directed catheters have transformed our capacity to safely and effectively treat dAVFs with a variety of anatomic configurations and locations. Innovative combinations of microsurgical and endovascular approaches are even being applied to select cases. In this issue of Neurosurgical Focus, we present a series of narrated videos that demonstrate the decision-making, vascular anatomy, and technical nuances of many of these advanced techniques, while also providing narrated videos demonstrating tried-and-true microsurgical and endovascular approaches that have proven highly effective over the years. We hope this video supplement provides a meaningful update and demonstration of modern microsurgical and endovascular approaches to patients with dAVF and aids all of us in our unending quest to provide even better care for our patients in the future. We thank the authors for their outstanding contributions.
Adam S. Arthur, Stephanie A. Wilson, Sanat Dixit and John D. Barr
The authors present a retrospective analysis of their initial experience with the recently developed MicroVention HydroCoil to treat patients with cerebral aneurysms. Unlike the bare metal coils initially available for endovascular treatment of aneurysms, HydroCoils have a layer of hydrogel polymer surrounding a platinum metallic core. The hydrogel polymer expands soon after making contact with blood. The expanded hydrogel polymer provides increased volumetric filling compared with bare metal coils and offers a more biocompatible surface, as demonstrated in animal models.
Over a 17-month period, the authors used HydroCoils to treat 30 patients with 33 aneurysms. All patients had been treated at least 6 months prior to data analysis. Initial treatment results as well as records of clinical and angiographic follow up were reviewed. Six-month posttreatment angiograms were available for 25 patients.
The HydroCoils were implanted with few complications. On angiographic follow up, a clearly defined radiolucent separation of the coils from the parent artery was noted in many of the aneurysms treated. The authors have not previously observed angiographically demonstrated lucencies separating the coils from the parent artery. This frequent, but not consistent, appearance on follow-up angiograms obtained in this study indicates that HydroCoils support significant neointimal formation across the neck of treated aneurysms. The preliminary results indicate that HydroCoils can be used safely and effectively to treat aneurysms and that these devices may allow for improved aneurysm filling.
Bernhard Sutter, Adam Arthur, Jeffrey Laurent, James Chadduck, Gerhard Friehs, Georg Clarici and Gerhard Pendl
Surgical treatment of intrameduallary spinal cord metastases (ISCM) has become increasingly effective in recent years. The advent of new imaging techniques combined with an enhanced understanding of the natural history of these tumors has improved the effectiveness of the available treatment options. The authors present three new cases of ISCM successfully treated with surgery. A review of 129 cases found in the literature is also discussed. Characteristic symptomology and presentation are reviewed with an eye toward improving diagnostic methodology. The natural history of ISCM is divided into three phases. Surgical intervention should be used early in phase 2.
John E. Wanebo, Hunter G. Louis, Adam S. Arthur, Jie Zhou, Neal F. Kassell, Kevin S. Lee and Gregory A. Helm
Cerebral vasospasm is a major complication of subarachnoid hemorrhage (SAH) after the rupture of an intracranial aneurysm. Although the cause of cerebral vasospasm has not been fully established, several lines of evidence suggest that the vasoconstrictor peptide endothelin (ET) may play a crucial role. In the present study the potential of TBC 11251 (TBC), a newly developed ETA receptor antagonist, to prevent and/or reverse cerebral vasospasm was examined in a well-established rabbit model of SAH.
Sixty-five New Zealand White rabbits were assigned to one of six groups. Experimental SAH was induced in rabbits comprising five of the groups by injecting autologous arterial blood into the cisterna magna. The treatment groups were as follows: 1) control (no SAH); 2) SAH only; 3) SAH + placebo at 24 and 36 hours (24/36); 4) SAH + TBC (24/36); 5) SAH + placebo twice daily (BID); and 6) SAH + TBC BID. All drug-treated animals received an intravenous dosage of 5 mg/kg TBC. After 48 hours, the animals were killed by intracardiac perfusion with fixative. The brainstems were removed and the basilar arteries (BAs) were prepared for histological examination. The cross-sectional area of each BA was measured using computer-assisted videomicroscopy by an investigator blind to the group from which it came. A one-way analysis of variance and paired group mean comparisons with the post-hoc Fisher least significant difference test were used for analysis of BA diameters and physiological parameters.
The model provided reliable vasospasm, with the mean BA cross-sectional area constricting from 0.388 mm2 in the control group to 0.106 mm2 (27.4% of control) in the SAH only group. Treatment with TBC (24/36) after SAH (reversal protocol) produced a mean BA area of 0.175 mm2 (44.2% of control) which, although larger than the placebo group value of 0.135 mm2 (39.9% of control), was not statistically significant. However, treatment with TBC BID (prevention protocol) produced a mean BA area of 0.303 mm2 (78.1% of control) compared with the placebo BID value of 0.134 mm2 (34.6% of control); this effect was statistically significant (p < 0.01). There were no side effects noted and no differences in the mean arterial pressures between drug and placebo groups.
These findings demonstrate that systemic administration of the ETA receptor antagonist TBC significantly attenuates cerebral vasospasm after SAH when given as a preventative therapy, and they provide additional support for the role of ET in the establishment of vasospasm.