OBJECTIVE Onyx HD-500 is a liquid embolic agent consisting of ethylene vinyl alcohol copolymer dissolved in dimethylsulfoxide and mixed with tantalum. This viscous embolic agent was designed to treat intracranial side wall aneurysms, but there have been no prospective published series from the United States. From this early experience, we developed several protocol revisions, technical details, and clinical pearls that have not been published for liquid embolic embolization of aneurysms. CLINICAL PRESENTATION We present our single-center prospective series of patients treated with Onyx HD-500 from a multicenter, randomized, controlled trial. Thirteen patients received Onyx HD-500, and their ages ranged from 43 to 81 years. Twelve patients had aneurysms on the internal carotid artery, and 1 patient had an aneurysm the vertebral artery. Every patient had an immediate postangiographic result with 90% or more occlusion by an independent core laboratory assessment. In 1 patient, the Onyx HD-500 injection was aborted, and the aneurysm was embolized with coils. Eleven of 13 patients (85%) underwent 6-month follow-up angiography that demonstrated persistent durable occlusion with no recanalization. There was 1 complication (8%) and no deaths. CONCLUSION This is the only prospective series of intracranial aneurysms treated with Onyx HD-500 in the United States. This is also the first publication that describes detailed procedure techniques, recommended protocol revisions, lessons learned from early complications, clinical pearls, and advantages and disadvantages of liquid embolic embolization of aneurysms.

OBJECTIVE: Onyx HD-500 is a liquid embolic agent consisting of ethylene vinyl alcohol copolymer dissolved in dimethylsulfoxide and mixed with tantalum. This viscous embolic agent was designed to treat intracranial side wall aneurysms, but there have been no prospective published series from the United States. From this early experience, we developed several protocol revisions, technical details, and clinical pearls that have not been published for liquid embolic embolization of aneurysms.CLINICAL PRESENTATION: We present our single-center prospective series of patients treated with Onyx HD-500 from a multicenter, randomized, controlled trial. Thirteen patients received Onyx HD-500, and their ages ranged from 43 to 81 years. Twelve patients had aneurysms on the internal carotid artery, and 1 patient had an aneurysm the vertebral artery. Every patient had an immediate postangiographic result with 90% or more occlusion by an independent core laboratory assessment. In 1 patient, the Onyx HD-500 injection was aborted, and the aneurysm was embolized with coils. Eleven of 13 patients (85%) underwent 6-month follow-up angiography that demonstrated persistent durable occlusion with no recanalization. There was 1 complication (8%) and no deaths.CONCLUSION: This is the only prospective series of intracranial aneurysms treated with Onyx HD-500 in the United States. This is also the first publication that describes detailed procedure techniques, recommended protocol revisions, lessons learned from early complications, clinical pearls, and advantages and disadvantages of liquid embolic embolization of aneurysms.

OBJECTIVE Interpretation of angioarchitecture during embolization of intracranial arteriovenous malformations (AVMs) is critical to optimizing results. We describe an adjunctive technique to aid in the interpretation of AVM embolization and improve safety. METHODS In the past 100 consecutive patients who underwent AVM embolization by a single surgeon (RAM), each AVM nidus was selectively catheterized and microangiography was performed. After the microcatheter contrast exited the AVM, guiding catheter angiography was performed during the same digital run. The microangiogram was digitally superimposed on the guiding catheter angiogram to delineate important landmarks such as the nidus perimeter, draining veins, and microcatheter tip, which were then drawn on the digital subtraction angiographic monitor with a marking pen in two orthogonal views. RESULTS Important landmarks were continually visualized during the embolization procedure despite subtracted fluoroscopy (“blank” roadmap). These techniques qualitatively helped to: 1) appreciate the overall size and morphology of the nidus, 2) clearly visualize the safe limits of the embolic injection within the nidus perimeter, 3) clearly visualize draining patterns to help avoid premature venous embolization, 4) decipher small draining veins from arteries, 5) continuously monitor the location and status of the microcatheter tip, and 6) increase the confidence of the surgeon during prolonged embolic injections. CONCLUSION The double injection technique, with marking pen demarcation of the nidus perimeter, venous drainage, and microcatheter tip position, was qualitatively useful in every case.

OBJECTIVE Angiographic roadmapping, commonly used for catheter navigation in endovascular procedures, is the superimposition of a live fluoroscopic image on a previously stored digitally subtracted angiogram. We evaluated this technique for the first time as a method for image-guided navigation during surgical resection of intracranial and spinal vascular lesions. METHODS After obtaining Institutional Review Board approval, we retrospectively reviewed 38 procedures in 35 patients at two centers performed by one neurosurgeon in which intraoperative roadmapping was used as an image-guided navigation tool for surgical resection of cranial and spinal arteriovenous malformations or fistulae. This technique requires femoral or radial artery access and a portable vascular C-arm capable of digitally subtracted angiogram and roadmap angiography in the operating room suite. Once a roadmap identifying the vascular lesion is obtained, a sterile radiopaque instrument is placed over the skin/wound to precisely localize the lesion in multiple dimensions. RESULTS Angiographic roadmapping was used for resection of seven spinal arteriovenous malformations or fistulae, 23 cranial arteriovenous malformations or fistulae, one aneurysm, two carotid-cavernous fistulae, and transtorcular embolization of five vein of Galen malformations. In all cases, the technique helped us to make precisely localized incisions, avoid unnecessary bone removal, and readily directed us to the vascular lesion. In several cases, it allowed localization of small fistulae not visible on magnetic resonance imaging or computed tomographic angiography scans. Finally, this approach facilitated immediate angiographic confirmation of complete resection at the end of each case. CONCLUSION Angiographic roadmapping is an effective intraoperative navigation tool for resection of vascular lesions that has not been previously described and offers several advantages to frameless stereotaxy.

BACKGROUND:Recently, a great interest has emerged regarding the use of abciximab for treatment of stroke. Thromboembolic events that occur during neuroendovascular procedures represent a unique subset of stroke patients because definitive angiographic diagnosis and treatment can be performed immediately. The existing literature on this situation suggests excellent results; however, most publications are case reports, and the largest series is 13 cases. We report our experience using abciximab in the treatment of acute thromboembolic events that occur during neuroendovascular procedures. METHODS:We reviewed the last 1373 consecutive patients who underwent neuroendovascular procedures at the University of Florida from our prospectively maintained clinical database. Of these patients, 29 (2.11%) endovascular cases were complicated by acute cerebral thromboembolic events that were treated with abciximab. Abciximab was administered in less than 1 hour after the onset of the occlusion in every patient. The Thrombolysis In Myocardial Infarction (TIMI) scale was used to measure immediate angiographic outcome, and the Modified Rankin Scale (MRS) was used to measure clinical outcome at the time of follow-up. Independent outcome was defined as an MRS of 3 or less at follow-up. RESULTS:Angiographic improvement in the TIMI grade was achieved in 29 (81%) of 36 arteries. Three intracerebral hemorrhages occurred with abciximab when administered with concurrent mechanical clot disruption; in two of these hemorrhages, recombinant tissue plasminogen activator (r-tPA) was also administered. The mean follow-up time for the living cohort was 7.54 months. Twenty-four (83%) patients were independent at follow-up, 3 (10%) were dependent at follow-up, and 2 (7%) died. CONCLUSION:Abciximab appears to be safe and effective in the treatment of acute cerebral thromboembolic complications during neuroendovascular procedures.

Background: Intraoperative angiography for neurovascular disease has gained wide acceptance as a useful tool. There are few published cases of intraoperative angiography performed in the prone or three-quarter prone position, and the transradial approach has not previously been described for this situation.Methods: We retrospectively reviewed our last 177 consecutive cases of intraoperative angiography performed for neurovascular disease. Of these cases, 21 were performed in the prone or three-quarter prone position. Two different approaches were used: (1) a previously described extended femoral sheath approach (13 cases) and (2) a newly described transradial approach (8 cases).Results: All 21 intraoperative angiograms were successfully completed in the prone or three-quarter prone position. This enabled us to make additional surgical adjustments when necessary or to conclude the operation. One complication, a dissection of the brachial artery, occurred during one intraoperative angiographic procedure.Conclusions: Intraoperative angiography can be performed in the prone or three-quarter prone position with good efficacy and safety. The transfemoral route has the advantage of familiarity, but has disadvantages of poor sterility at access site, possible kinking or thrombosis of the sheath, and possible skin injury while resting on the tubing during long procedures. The transradial route has advantages of continuous access to the entry site throughout the surgical procedure and ease of catheterization of vertebral arteries for occipital and suboccipital lesions. However, the transradial route has the disadvantage of working from an unfamiliar approach, especially for spinal arteriovenous malformations. (c) 2006 Elsevier Inc. All rights reserved.

Rupture of a cerebral arteriovenous malformation can result in devastating hemorrhage with a possibility of serious neurological injury or death. Endovascular embolization is an important adjunct in the treatment of cerebral arteriovenous malformations, and in a small number of cases may provide definitive treatment. Currently available embolic agents have several shortcomings, including the possibility of recanalization, adhesiveness to the endovascular microcatheter and suboptimal handling at the time of surgical resection. Onyx® is an ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide that was approved by the US FDA in July 2005 as an embolic agent for brain arteriovenous malformations. Although long-term follow-up is limited, this agent appears to offer several advantages over the other available embolic agents for the endovascular management of arteriovenous malformations and other vascular lesions.

OBJECT The aim of this study was to evaluate the pathophysiology underlying headache associated with cough in patients with Chiari I tonsillar abnormality. The authors hypothesized that peak intrathecal pressure during coughing is higher in patients with headache aggravated by cough than in patients without or in healthy volunteers. In addition, the authors evaluated the use of intrathecal pressure during cough as a means of assessing obstruction to the free flow of cerebrospinal fluid (CSF) at the craniocervical junction. METHODS Twenty-six adult patients with Chiari I malformation and syringomyelia, four adult patients with Chiari I malformation without syringomyelia, and 15 healthy volunteers were prospectively studied. Testing before surgery included the following: 1) clinical evaluation for the presence of headache associated with cough; and 2) evaluation of lumbar subarachnoid pressure at rest, during three to five coughs, while performing the Valsalva maneuver, during jugular compression, and after removal of CSF. Patients underwent suboccipital craniectomy, C-1 laminectomy, and duraplasty. Testing was repeated 6 months after surgery. CONCLUSIONS Peak intrathecal pressures during cough and at baseline were elevated in patients with headache associated with cough compared with either patients without headache or healthy volunteers. After surgery, intrathecal pressures during cough were significantly lower than preoperative values and headache aggravated by cough was resolved partially or completely. Headache linked to coughing in patients with Chiari I malformation is associated with sudden increased intrathecal pressure caused by obstruction to the free flow of CSF in the subarachnoid space.

OBJECT Syringomyelia causes progressive myelopathy. Most patients with syringomyelia have a Chiari I malformation of the cerebellar tonsils. Determination of the pathophysiological mechanisms underlying the progression of syringomyelia associated with the Chiari I malformation should improve strategies to halt progression of myelopathy. METHODS The authors prospectively studied 20 adult patients with both Chiari I malformation and symptomatic syringomyelia. Testing before surgery included the following: clinical examination; evaluation of anatomy by using T1-weighted magnetic resonance (MR) imaging; evaluation of the syrinx and cerebrospinal fluid (CSF) velocity and flow by using phase-contrast cine MR imaging; and evaluation of lumbar and cervical subarachnoid pressure at rest, during the Valsalva maneuver, during jugular compression, and following removal of CSF (CSF compliance measurement). During surgery, cardiac-gated ultrasonography and pressure measurements were obtained from the intracranial, cervical subarachnoid, and lumbar intrathecal spaces and syrinx. Six months after surgery, clinical examinations, MR imaging studies, and CSF pressure recordings were repeated. Clinical examinations and MR imaging studies were repeated annually. For comparison, 18 healthy volunteers underwent T1-weighted MR imaging, cine MR imaging, and cervical and lumbar subarachnoid pressure testing. Compared with healthy volunteers, before surgery, the patients had decreased anteroposterior diameters of the ventral and dorsal CSF spaces at the foramen magnum. In patients, CSF velocity at the foramen magnum was increased, but CSF flow was reduced. Transmission of intracranial pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was partially obstructed. Spinal CSF compliance was reduced, whereas cervical subarachnoid pressure and pulse pressure were increased. Syrinx fluid flowed inferiorly during systole and superiorly during diastole on cine MR imaging. At surgery, the cerebellar tonsils abruptly descended during systole and ascended during diastole, and the upper pole of the syrinx contracted in a manner synchronous with tonsillar descent and with the peak systolic cervical subarachnoid pressure wave. Following surgery, the diameter of the CSF passages at the foramen magnum increased compared with preoperative values, and the maximum flow rate of CSF across the foramen magnum during systole increased. Transmission of pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was normal and cervical subarachnoid mean pressure and pulse pressure decreased to normal. The maximum syrinx diameter decreased on MR imaging in all patients. Cine MR imaging documented reduced velocity and flow of the syrinx fluid. Clinical symptoms and signs improved or remained stable in all patients, and the tonsils resumed a normal shape. CONCLUSIONS The progression of syringomyelia associated with Chiari I malformation is produced by the action of the cerebellar tonsils, which partially occlude the subarachnoid space at the foramen magnum and act as a piston on the partially enclosed spinal subarachnoid space. This creates enlarged cervical subarachnoid pressure waves that compress the spinal cord from without, not from within, and propagate syrinx fluid caudally with each heartbeat, which leads to syrinx progression. The disappearance of the abnormal shape and position of the tonsils after simple decompressive extraarachnoidal surgery suggests that the Chiari I malformation of the cerebellar tonsils is acquired, not congenital. Surgery limited to suboccipital craniectomy, C-I laminectomy, and duraplasty eliminates this mechanism and eliminates syringomyelia and its progression without the risk of more invasive procedures.