Fady T. Charbel

Selection of cerebral aneurysms for treatment using Guglielmi detachable coils: the preliminary University of Illinois at Chicago experience.

OBJECTIVE We present our initial experience with Guglielmi detachable coils (GDCs). The aim of this study was to determine the criteria for aneurysms, ruptured or unruptured, that are suitable for this technique. The importance of aneurysm geometry and its impact on the final results are discussed. METHODS A retrospective analysis of 329 patients with 339 cerebral aneurysms that were treated at the University of Illinois Hospital at Chicago from May 1994 to June 1997 was conducted. One hundred eighty-five patients were treated surgically, and 144 were selected for treatment using GDCs. Of the 144 patients selected for GDC treatment, 55 patients with 55 aneurysms were admitted during the acute phase of subarachnoid hemorrhage and 89 patients with 97 aneurysms had nonruptured aneurysms or were treated after clinical recovery of previously ruptured aneurysms. All procedures were performed with the patients under general anesthesia and with systemic heparinization using live simultaneous biplane roadmapping, with the exception of the first four patients. These patients were treated before the installation of the biplane system. The percentage of aneurysm occlusion was determined at the end of each procedure. Follow-up angiography was scheduled to be performed at 6 months, 1 year, and 2 years after treatment. PATIENT SELECTION For the initial 25 patients (Group 1), selection for coiling was restricted to nonsurgical candidates or patients in whom coiling was thought to be the best treatment choice, based on medical condition and location of the aneurysm. The geometry of the aneurysm was not considered to be an important factor in the selection for coiling. The remaining patients (Group 2) were selected for coiling based on aneurysm geometry, as determined by pretherapeutic angiography. Aneurysms that were considered to be favorable for coiling included those that had a dome-to-neck ratio of at least 2 and an absolute neck diameter less than 5 mm. RESULTS The initial 25 patients (Group 1) were treated from May 1994 to February 1995. There were high morbidity and mortality rates, with 56% of the treated aneurysms occluded at 6 months. The remaining patients (Group 2) consisted of 119 patients with 123 aneurysms. There was no mortality directly related to the coiling procedure, and permanent morbidity was limited to 1.0%. Three patients (2.5%) developed transient neurological deficits secondary to the procedure, and seven patients (5.8%) experienced periprocedural complications that did not result in neurological sequelae. The morphological results were strongly correlated to the geometry of the aneurysms, with a complete occlusion rate of 72% among the acutely ruptured aneurysms and 80% among the nonacute aneurysms, when patients were selected for treatment based on the geometry of the aneurysms and the dome-to-neck ratio was at least 2. The occlusion rate dropped to 53% when selection was not based on aneurysm geometry and the dome-to-neck ratio was less than 2. A summary of the morphological outcomes for the Group 2 patients shows that 86% of the aneurysms that initially underwent coiling using GDCs were completely occluded (78% by coils alone, 3.0% in conjunction with surgery, and 5.0% with parent artery occlusion). Residual small neck remnants were present in 11% of the Group 2 aneurysms (3.0% were scheduled for surgical treatment of residual neck remnant growths not amenable to further endovascular treatment, and 8% were scheduled for initial 6-mo follow-up examinations). Death resulting from unrelated causes before initial follow-up occurred in 3.0% of the patients. CONCLUSION These preliminary results suggest that using GDCs is a safe technique resulting in low morbidity and mortality rates for the treatment of intracranial aneurysms in appropriately selected patients. The percentage of complete aneurysm occlusion is related to the density of coil packing, which is strongly dependent on the geometry of the aneurysm. Optim

Embolization of the Nidus of Brain Arteriovenous Malformations withn-Butyl Cyanoacrylate

OBJECTIVE To demonstrate that nidus embolization of brain arteriovenous malformations (AVMs) with Histoacryl (B. Braun, Melsungen, Germany) is effective and yields low morbidity and mortality rates. METHODS We present a retrospective analysis of 54 brain AVMs treated at the University of Illinois at Chicago from April 1994 to December 1995. Treatment modalities included embolization in all cases and then surgical resection or radiosurgery. INSTRUMENTATION The nidus was reached with the combined use of a Magic microcatheter (Balt, Montmorency, France) and a Terumo 0.010-inch guidewire. TECHNIQUE Embolization was performed only when the tip of the microcatheter was wedged into the nidus of the AVMs with no reflux of contrast proximally. The embolization was performed using simultaneous biplane roadmapping with the patient under general anesthesia without Amytal testing. RESULTS Twenty-six of 54 patients are still waiting for more radical treatment. Two deaths and two minor and one severe permanent neurological deficit occurred. Three patients were cured with embolization alone; 11 patients were cured after surgical resection. Three patients underwent radiosurgery, with one cure after 1 year. CONCLUSION Nidus embolization with Histoacryl is an effective technique that permits complete cure of a large number of brain AVMs, with or without surgical resection and/or radiosurgery.

Follow-up angiography of intracranial aneurysms treated with endovascular placement of Guglielmi detachable coils.

OBJECTIVE The success of endovascular treatment of intracranial aneurysms with Guglielmi detachable coils (GDCs) is dependent on the long-term exclusion of the aneurysm from the circulation. We reviewed our experience with the long-term angiographic follow-up monitoring of aneurysms that had been treated with GDCs. METHODS All patients whose aneurysms had been treated with GDCs between January 1995 and August 1999 and who subsequently underwent follow-up angiography at 6 months or more were included in this study. We reviewed all of the angiographic findings, to determine the percentage of aneurysm occlusion on the initial angiograms and on the last available follow-up angiograms. The categories of aneurysm occlusion used were 100%, ≥95%, and less than 95% occlusion. RESULTS One hundred thirty patients with 141 aneurysms underwent 143 endovascular coiling procedures and subsequently underwent angiographic follow-up monitoring of 6 months or more. There were 102 female and 28 male patients. The mean angiographic follow-up period was 16.7 months (range, 6–62 mo). The initial rates of occlusion were 100% for 56 aneurysms (39%), ≥95% for 65 aneurysms (46%), and less than 95% for 22 aneurysms (15%). Recurrence of one aneurysm (1.8%) was observed. Of the 87 aneurysms that were incompletely occluded initially, there was progressive thrombosis in 40 (46%), stable neck remnants in 23 (26%), and enlargement of the residual neck in 24 (28%). The final occlusion rates, determined on the last available angiograms, were 100% for 88 aneurysms (61%), ≥95% for 31 aneurysms (22%), and less than 95% for 24 aneurysms (17%). No patient experienced repeat or new subarachnoid hemorrhage more than 6 months after the initial treatment. CONCLUSION Late angiographic follow-up monitoring of aneurysms that have been treated with GDCs demonstrates the durability of the treatment. Aneurysms with large residual neck remnants were subjected to further treatment, whereas aneurysms with small residual neck remnants remain under observation.

Brain tissue oxygen, carbon dioxide, and pH in neurosurgical patients at risk for ischemia.

A sensor that measures oxygen pressure (PO2), carbon dioxide pressure (PCO2), and pH was evaluated in brain tissue of patients at risk for ischemia.The sensor is 0.5 mm in diameter and was inserted into cortex tissue in 14 patients undergoing craniotomy for cerebrovascular surgery. A compromised cerebral circulation was identified in 8 of 14 patients by single photon emission computed tomography (SPECT) scan, cerebral angiography, and transient ischemic episodes before surgery. Under baseline conditions with isoflurane anesthesia and normal blood gases, tissue PO2 was lower in the eight compromised compared to six noncompromised patients (noncompromised 37 +/- 12 mm Hg, compromised 10 +/- 5 mm Hg; P < 0.05), PCO2 was increased (noncompromised 49 +/- 5 mm Hg, compromised 72 +/- 23 mm Hg; P < 0.05), and pH was decreased (noncompromised 7.16 +/- 0.08, compromised 6.82 +/- 0.21; P < 0.05). Critical tissue values for the identification of ischemia were a PO2 of 20 mm Hg, PCO2 of 60 mm Hg, and a pH of 7.0. These results suggest that brain tissue measures of PO2, PCO2, and pH provide information on the adequacy of cerebral perfusion in neurosurgical patients. (Anesth Analg 1996;82:582-6)

Virtual reality in neurosurgical education: Part-task ventriculostomy simulation with dynamic visual and haptic feedback

OBJECTIVE Mastery of the neurosurgical skill set involves many hours of supervised intraoperative training. Convergence of political, economic, and social forces has limited neurosurgical resident operative exposure. There is need to develop realistic neurosurgical simulations that reproduce the operative experience, unrestricted by time and patient safety constraints. Computer-based, virtual reality platforms offer just such a possibility. The combination of virtual reality with dynamic, three-dimensional stereoscopic visualization, and haptic feedback technologies makes realistic procedural simulation possible. Most neurosurgical procedures can be conceptualized and segmented into critical task components, which can be simulated independently or in conjunction with other modules to recreate the experience of a complex neurosurgical procedure. METHODS We use the ImmersiveTouch (ImmersiveTouch, Inc., Chicago, IL) virtual reality platform, developed at the University of Illinois at Chicago, to simulate the task of ventriculostomy catheter placement as a proof-of-concept. Computed tomographic data are used to create a virtual anatomic volume. RESULTS Haptic feedback offers simulated resistance and relaxation with passage of a virtual three-dimensional ventriculostomy catheter through the brain parenchyma into the ventricle. A dynamic three-dimensional graphical interface renders changing visual perspective as the users head moves. The simulation platform was found to have realistic visual, tactile, and handling characteristics, as assessed by neurosurgical faculty, residents, and medical students. CONCLUSION We have developed a realistic, haptics-based virtual reality simulator for neurosurgical education. Our first module recreates a critical component of the ventriculostomy placement task. This approach to task simulation can be assembled in a modular manner to reproduce entire neurosurgical procedures.

What percentage of surgically clipped intracranial aneurysms have residual necks

OBJECTIVE To determine the angiographically proven rate and persistence of occlusion of intracranial aneurysms after surgical clipping as reported in the literature. This should establish a basis for comparing surgery with new endovascular methods of treatment. METHODS We reviewed the literature published during the period from 1979 through 1999, dividing the articles into two groups. The first group of articles reported patients undergoing surgical treatment with immediate postoperative angiography. The second group of articles documented symptomatic recurrence or regrowth of aneurysms that were surgically treated previously. The data from these articles are presented for analysis. RESULTS During the period 1979 to 1999, six series of patients undergoing surgical treatment of aneurysms with immediate postoperative angiography were reported. These reported series comprised a total of 1,397 patients, of whom 1,370 underwent postoperative angiography demonstrating 1,569 clipped aneurysms. Residual filling was found in 82 aneurysms (5.2%) on postoperative angiography. Of the 1,370 patients, only 124 patients with 169 aneurysms were reported to have had any long-term angiographic follow-up. The second group consisted of 226 patients representing six reported groups of patients, who either presented up to 24 years after aneurysm clipping with recurrent symptoms of hemorrhage or mass effect, or had important findings on intraoperative and postoperative angiograms. CONCLUSION The lack of information regarding both the frequency of residual filling or regrowth and long-term angiographic follow-up of patients with surgically treated aneurysms makes meaningful comparison between surgical treatments and new treatment methods for intracranial aneurysms difficult or impossible. Detailed analysis with high-quality angiography should be performed to determine the success of surgical treatment.

Improved phase-contrast flow quantification by three-dimensional vessel localization

In this paper, a method of three-dimensional (3D) vessel localization is presented to allow the identification of a vessel of interest, the selection of a vessel segment, and the determination of a slice orientation to improve the accuracy of phase-contrast magnetic resonance (PCMR) angiography. A marching-cube surface-rendering algorithm was used to reconstruct the 3D vasculature. Surface-rendering was obtained using an iso-surface value determined from a maximum intensity projection (MIP) image. This 3D vasculature was used to find a vessel of interest, select a vessel segment, and to determine the slice orientation perpendicular to the vessel axis. Volumetric flow rate (VFR) was obtained in a phantom model and in vivo using 3D localization with double oblique cine PCMR scanning. PCMR flow measurements in the phantom showed 5. 2% maximum error and a standard deviation of 9 mL/min during steady flow, 7.9% maximum error and a standard deviation of 13 mL/min during pulsatile flow compared with measurements using an ultrasonic transit-time flowmeter. PCMR VFR measurement error increased with misalignment at 10, 20, and 30 degrees oblique to the perpendicular slice in vitro and in vivo. The 3D localization technique allowed precise localization of the vessel of interest and optimal placement of the slice orientation for minimum error in flow measurements.

Monobloc craniomaxillofacial distraction osteogenesis in a newborn with severe craniofacial synostosis: A preliminary report

Severe craniofacial synostosis can be a devastating problem for a newborn infant. Reasons for early surgical intervention include cranial stenosis, hydrocephalus, inadequate globe and corneal protection, compromised airway patency, and feeding problems. In this preliminary report, we describe the management of severe craniofacial synostosis in a newborn infant by means of cranial and midfacial distraction osteogenesis.

Regional Cerebral Blood Flow Using Quantitative MR Angiography

BACKGROUND AND PURPOSE: We sought to derive regional cerebral blood flow using vessel flows from quantitative MR angiography (qMRA). MATERIALS AND METHODS: Flow rates in the 15 major cerebral arteries were measured on retrospectively gated fast 2D phase-contrast MR angiography obtained in 83 healthy adult volunteers (age range, 24–74 years; mean, 42 years). The arterial network of the brain was partitioned into 12 different regions, in which flows were calculated from the measured flows of the 15 cerebral arteries. RESULTS: The mean flows of the 15 arteries and the 12 regions were calculated. The mean total cranial flow and the mean total cerebral blood flow were 949 ± 158 mL/min and 695 ± 113 mL/min, respectively. The mean regional flows for the anterior and posterior circulation were 483 ± 87 mL/min and 212 ± 34 mL/min, respectively. The relative contributions of the flows in the 11 regions to their parent regions were obtained. The mean flows in the individual arteries and the regions with age were also calculated. The mean flows for the female group were significantly lower than those for the male group (P < .001) for the 2 common carotids and the cranial circulation and left/right extracranial circulation. However, the intracranial circulation was not different between sexes. CONCLUSIONS: The 12 regions in the cerebral circulation were identified and formed into a partition tree, and the mean regional flow for each region was determined using vessel flows from qMRA.

Use of Quantitative Magnetic Resonance Angiography to Stratify Stroke Risk in Symptomatic Vertebrobasilar Disease

Background and Purpose— Symptomatic vertebrobasilar disease (VBD) carries a high risk of recurrent stroke. We sought to determine whether a management algorithm consisting of quantitative hemodynamic assessment could stratify stroke risk and guide the need for intervention. Methods— All patients with symptomatic VBD at our institution are evaluated by a standard protocol including quantitative magnetic resonance angiography (QMRA). Patients are stratified on the basis of the presence or absence of distal flow compromise. Those with low distal flow are offered intervention (surgical or endovascular); all patients receive standard medical therapy. We reviewed the clinical outcome of patients managed with this protocol from 1998 to 2003. Results— Follow-up was available for 47 of 50 patients over a mean interval of 28 months. Stroke and combined stroke/transient ischemic attack free survival at 2 years was calculated using the Kaplan–Meier curve. Patients with normal distal flow (n=31) had an event-free survival of 100% and 96%, respectively. Comparatively, patients with low distal flow (n=16) experienced a 71% and 53% event-free survival, demonstrating a significantly higher risk of recurrent ischemia (P=0.003). Patients with low flow who subsequently underwent treatment (n=12) had an 82% event-free survival. Cox proportional hazards analysis demonstrated that flow status affected event-free survival regardless of covariates. Conclusions— Patients with symptomatic VBD demonstrating low distal flow on QMRA appear to have a high risk of stroke; conversely, those with normal flow seem to have a benign course and may be optimally managed with medical therapy alone.