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Background and purposeThe ability of polymer-modified coils to promote stable aneurysm occlusion after endovascular treatment is not well-documented. Angiographic aneurysm recurrence is widely used as a surrogate for treatment failure, but studies documenting the correlation of angiographic recurrence with clinical failure are limited. This trial compares the effectiveness of Matrix(2) polyglycolic/polylactic acid biopolymer-modified coils with bare metal coils and correlates the angiographic findings with clinical failure (ie, target aneurysm recurrence), a composite end point that includes any incident of posttreatment aneurysm rupture, retreatment, or unexplained death.Materials and methodsThis was a multicenter randomized noninferiority trial with blinded end point adjudication. We enrolled 626 patients, divided between Matrix(2) and bare metal coil groups. The primary outcome was target aneurysm recurrence at 12 ± 3 months.ResultsAt 455 days, at least 1 target aneurysm recurrence event had occurred in 14.6% of patients treated with bare metal coils and 13.3% of Matrix(2) (P = .76, log-rank test) patients; 92.8% of target aneurysm recurrence events were re-interventions for aneurysms that had not bled after treatment, and 5.8% of target aneurysm recurrence events resulted from hemorrhage or rehemorrhage, with or without retreatment. Symptomatic re-intervention occurred in only 4 (0.6%) patients. At 455 days, 95.8% of patients with unruptured aneurysms and 90.4% of those with ruptured aneurysms were independent (mRS ≤ 2). Target aneurysm recurrence was associated with incomplete initial angiographic aneurysm obliteration, presentation with rupture, and a larger aneurysmal dome and neck size.ConclusionsTested Matrix(2) coils were not inferior to bare metal coils. Endovascular coiling of intracranial aneurysms was safe, and the rate of technical success was high. Target aneurysm recurrence is a promising clinical outcome measure that correlates well with established angiographic measurements.

Background: No randomized trial of intracranial aneurysm coiling has compared long-term efficacy of polymer-modified coils to bare metal coils (BMCs). We report 5-year results comparing Matrix 2 coils to BMCs. The primary objective was to compare the rates of target aneurysm recurrence (TAR) at 12 months. Secondary objectives included angiographic outcomes at TAR or 12 months and TAR at 5 years., Methods: A total of 626 patients were randomized to BMCs or Matrix 2 coils. Detailed methods and 1-year results have been published previously., Results: Of 580 patients eligible for 5-year follow-up, 431 (74.3%) completed follow-up or reached TAR. Matrix 2 coils were non-inferior to BMCs (P=0.8) but did not confer any benefit. Core lab reported post-treatment residual aneurysm filling (Raymond III) correlated with TAR (P<0.0001) and with aneurysm hemorrhage after treatment (P<0.008). Repeat aneurysmal hemorrhage after treatment, but before hospital discharge, occurred in three patients treated for acutely ruptured aneurysms. Additionally, two patients treated for unruptured aneurysms experienced a first hemorrhage during follow-up. All five hemorrhages resulted from aneurysms with Raymond III residual aneurysm filling persisting after initial treatment. After 5 years follow-up, 2/626 (0.3%) patients are known to have had target aneurysm rupture following hospital discharge. The annualized rate of delayed hemorrhage after coiling was 2/398/5=0.001 (0.1%) per year for unruptured aneurysms and 0 for ruptured aneurysms., Conclusions: After 5 years Matrix 2 coils were non-inferior to BMCs but no benefit was demonstrated. Post-treatment residual angiographic aneurysm filling (Raymond III) is strongly associated with TAR (P<0.0001) and post-treatment aneurysmal hemorrhage (P=0.008)., Competing Interests: Competing interests: SWH: core lab services for Stryker and MicroVention Terumo (money paid to UCSF, over $5K); consulting for Microvention Terumo (money paid to Dr Hetts, under $5K). CGM: consultant for Medtronic and Microvention. JCC: consultant for Stryker. AB: consultant for Stryker, Microvention, Balt, and Phenox. AKW: research grant from Philips Medical; serves as a consultant for Stryker and Phenox; is a stockholder of InNeuroCo, EpiEP, Neural Analytics, Rist, Analytics 4 Life, and ThrombX; and is on the Speakers’ Bureau for SCENT trial (Surpass Intracranial Aneurysm Embolization System Pivotal Trial to Treat Large or Giant Wide Neck Aneurysms) presentations. AG: consultant for Microvention and emeritus consultant at Newcastle upon Tyne Hospitals NHS Trust. CFD: chief adjudicator, Stryker EVOLVE Trial Core Angiography Lab (salary support to department)., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Purpose- The WEAVE trial (Wingspan Stent System Post Market Surveillance) is a postmarket surveillance trial mandated by the Food and Drug Administration to assess the periprocedural safety of the Wingspan Stent system in the treatment of symptomatic intracranial atherosclerotic disease. Methods- A total of 152 consecutive patients who met the Food and Drug Administration on-label usage criteria were enrolled at 24 hospitals and underwent angioplasty and stenting with the Wingspan stent. On-label criteria included age 22 to 80 years, symptomatic intracranial atherosclerotic stenosis of 70% to 99%, baseline modified Rankin Scale score ≤3, ≥2 strokes in the vascular territory of the stenotic lesion with at least 1 stroke while on medical therapy, and stenting of the lesion ≥8 days after the last stroke. The primary analysis assessed the periprocedural stroke, bleed, and death rate within 72 hours of the procedure with adjudication by a core study Stroke Neurologist. Results- The trial was stopped early after interim analysis of 152 consecutive patients demonstrated a lower than expected 2.6% (4/152 patients) periprocedural stroke, bleed, and death rate. This was lower than the 4% periprocedural primary event safety benchmark set for the interim analysis in the study. A total of 97.4% (148/152) patients were event-free at 72 hours, 1.3% (2/152) had nonfatal strokes, and 1.3% (2/152) of patients died. Conclusions- With experienced interventionalists, and proper patient selection following the on-label usage guidelines, the use of the Wingspan stent for intracranial atherosclerotic disease demonstrated a low periprocedural complication rate and excellent safety profile. This is the largest on-label, multicenter, prospective trial of the Wingspan stent system to date with the lowest reported complication rate. Clinical Trial Registration- URL: https://www.clinicaltrials.gov . Unique identifier: NCT02034058.

Background and Purpose: The ability of polymer-modified coils to promote stable aneurysm occlusion after endovascular treatment is not well-documented. Angiographic aneurysm recurrence is widely used as a surrogate for treatment failure, but studies documenting the correlation of angiographic recurrence with clinical failure are limited. This trial compares the effectiveness of Matrix(2) polyglycolic/polylactic acid biopolymer-modified coils with bare metal coils and correlates the angiographic findings with clinical failure (ie, target aneurysm recurrence), a composite end point that includes any incident of posttreatment aneurysm rupture, retreatment, or unexplained death., Materials and Methods: This was a multicenter randomized noninferiority trial with blinded end point adjudication. We enrolled 626 patients, divided between Matrix(2) and bare metal coil groups. The primary outcome was target aneurysm recurrence at 12 ± 3 months., Results: At 455 days, at least 1 target aneurysm recurrence event had occurred in 14.6% of patients treated with bare metal coils and 13.3% of Matrix(2) (P = .76, log-rank test) patients; 92.8% of target aneurysm recurrence events were re-interventions for aneurysms that had not bled after treatment, and 5.8% of target aneurysm recurrence events resulted from hemorrhage or rehemorrhage, with or without retreatment. Symptomatic re-intervention occurred in only 4 (0.6%) patients. At 455 days, 95.8% of patients with unruptured aneurysms and 90.4% of those with ruptured aneurysms were independent (mRS ≤ 2). Target aneurysm recurrence was associated with incomplete initial angiographic aneurysm obliteration, presentation with rupture, and a larger aneurysmal dome and neck size., Conclusions: Tested Matrix(2) coils were not inferior to bare metal coils. Endovascular coiling of intracranial aneurysms was safe, and the rate of technical success was high. Target aneurysm recurrence is a promising clinical outcome measure that correlates well with established angiographic measurements., (© 2014 by American Journal of Neuroradiology.)

Objective: Deployment of a Neuroform microstent (NFM; Boston Scientific/Target, Freemont, California, USA) within acutely angled geometry may result in substantial deformations. This in vitro study was conducted to validate a novel alternative technique, consisting of intentional deployment of a NFM straight on into a terminus aneurysm, by assessing the mechanics, feasibility, and stability of the coils., Methods: Silicon models of wide-neck terminus aneurysms were constructed. Straight-on deployment of a NFM from the afferent vessel into the aneurysm was compared with conventional cross-neck deployment at a right angle position followed by Guglielmi detachable coil embolization simulation. The supporting forces of the two different methods of deployment were compared by the use of side-wall eccentric and en-face compression tests., Results: Straight-on deployment of a NFM at a wide-neck terminus aneurysm was a relatively simple technique compared with cross-neck right angle deployment. Good stability of the coil mass was consistently achieved with adequate preservation of the parent vessel lumen. A larger residual neck space at the side without the stent and much coil mass protruding into the parent vessel were observed in cross-neck stent deployment. Compression tests revealed a larger supporting force of the NFM with straight-on deployment compared with the side-wall radial force (P < 0.05). A potential problem with this technique is the possible inability or difficulty in retrieving a partially deployed coil., Conclusions: Stent-assisted coiling of wide-neck terminus aneurysms with straight-on deployment of NFM consistently achieved a stable NFM-coil complex. The NFM also had a better supporting force in a straight position. Some technical difficulties may be encountered during subsequent coiling. This alternative technique to conventional cross-neck bridging appears to be another strategy for wide-neck terminus aneurysm coiling., (Copyright © 2013 Elsevier Inc. All rights reserved.)

We report a case of atretic parietal cephalocele with a persistent parietal falcine sinus and partial absence of the straight sinus. The direct puncture angiographic study demonstrated that there was a major venous channel through the parietal skull defect. From the embryological point of view, this association may provide us with possible pathoetiologic evidence of congenital sinus pericranii is one of the alternative venous drainage pathways to compensate venous outflow in the cases of intracranial developmental anomalies., (Copyright © 2011 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Purpose: To compare the clinical and angiographic outcomes of endovascular treatment of symptomatic intracranial stenosis between octogenarian and younger patients., Methods: Data for 244 consecutive patients (173 men; mean age 61.6 years) who underwent angioplasty and/or stenting for intracranial atherosclerotic disease at 5 specialized centers were pooled. Baseline, 30-day, and follow-up clinical and angiographic information were collected. Rates of clinical and angiographic endpoints were compared between patients >or=80 years old versus those <80 years., Results: Patients >or=80 years (n = 15) were more likely to be hypertensive (87% versus 69%) and have underlying coronary artery disease (73% versus 36%, p<0.05) compared to younger patients (n = 229). The rate of periprocedural stroke and/or death was 3-fold higher among patients aged >or=80 years compared with those <80 years (20% versus 7%, p = 0.11). No recurrent stroke or death (excluding periprocedural events) was observed during follow-up in the octogenarian group. In patients who had follow-up angiography, a similar rate of >or=50% restenosis was observed among patients aged >or=80 years and those aged <80 years (25% versus 29%, p>0.1)., Conclusion: The 3-fold higher periprocedural death and/or stroke rate suggests cautious use of intracranial angioplasty and/or stent placement in octogenarians.

Background: Antiplatelet agents are required to prevent thromboembolic complications from recently deployed intracranial stents, yet they carry a risk of bleeding complications that may be serious in patients with recent subarachnoid hemorrhage., Method: Consecutive patients at a single institution who had ruptured intracranial saccular aneurysms treated with stent assisted coiling were retrospectively reviewed. Our primary outcomes were ischemic stroke related to the stent and bleeding complications possibly related to antithrombotic therapy. Secondary outcomes included 3 month follow-up National Institute of Health Stroke Scale (NIHSS) scores and modified Rankin Scale (mRS) scores., Results: 44 aneurysms in 42 patients were treated. Seven patients experienced ischemic strokes during their hospitalization. Five ischemic strokes were secondary to vasospasm; one was definitely related to thrombus formation within the stent and one was possibly related to the stent. Two patients had asymptomatic intracranial hemorrhages and one patient had a symptomatic intracranial hemorrhage. Patients with Hunt and Hess grades I-II (n=25) experienced no stent associated ischemic strokes or symptomatic intracranial hemorrhages. The two stent associated ischemic strokes and one symptomatic intracranial hemorrhage occurred in patients with Hunt and Hess grades III-V (n=17) and patients with external ventricular drains (EVDs) (n=17). Only one patient had disability at the 3 month follow-up that was possibly related to the stent (mRS score of 3 and NIHSS score of 2)., Conclusion: These data suggest that higher grade hemorrhage patients, especially those with EVDs, are at greater risk for ischemic stroke and/or bleeding complications than lower grade patients. However, the complications had a small impact on mid-term disability outcomes in this cohort.

Introduction: The study's purpose is to report the technical and clinical outcomes of a patient cohort that underwent vertebral artery ostium stent placement for atherosclerotic stenosis., Methods: We retrospectively analyzed a prospectively collected database of neurointerventional procedures performed at a single center from 1999 to 2005. Outcome measures included recurrent transient neurological deficits (TNDs), stroke, and death. Kaplan-Meier analysis was used to estimate stroke- and/or death-free survival at 12 months. Cox proportional hazard was used to identify risk factors for recurrent vertebrobasilar ischemic events., Results: Seventy-two patients with 77 treated vertebral ostial lesions were included. The 30-day stroke and/or death rate was 5.2% (n = 4), although no event was directly related to the vertebral ostium stent placement. Three procedure-related strokes were secondary to attempted stent placement at other sites (one carotid artery and two basilar arteries), and the one death was secondary to the presenting stroke severity. The mean clinical follow-up time available for 66 patients was 9 months. There were 14 TNDs (21%), two strokes (3%), and two deaths (3%) recorded in the follow-up. Recurrent vertebrobasilar ischemic events occurred in nine patients (seven TNDs and two strokes). No recurrent stroke and/or deaths were related to the treated vertebral ostium. Stroke- and/or death-free survival rate (including periprocedural stroke and/or death) was 89 +/- 5% at 12 months. No vascular risk factor was significantly associated with recurrent vertebrobasilar ischemic events., Conclusions: Vertebral artery ostium stent placement can be safely and effectively performed with a low rate of recurrent stroke in the territory of the treated vessel. Patients who also underwent attempted treatment of a tandem intracranial stenosis appeared to be at highest risk for periprocedure stroke.

Purpose: To determine whether vascular risk factors, underlying vessel diameter, and/or the type of stent affect restenosis rates for vertebral ostium stents., Methods: A single-center retrospective analysis was conducted of 44 patients (31 men; mean age 61 years, range 32-81) who underwent stenting of 48 ostial lesions in the vertebral arteries between 1999 and 2005. Only patients who underwent angiographic follow-up were included in the analysis. Cox regression analysis was utilized for risk factor association with binary restenosis (> or =50% versus <50%). Stent types and stent categories were compared for differences in binary restenosis rates and lumen gain at follow-up angiography., Results: Twenty-three (48%) of 48 lesions had > or =50% stenosis at a mean follow-up of 7.7 months. Cigarette smoking was associated with higher binary restenosis rates (p=0.025), while hypertension, diabetes, hyperlipidemia, history of neck radiation, and known coronary artery and/or peripheral vascular disease were not. Reduced binary restenosis rates and improved lumen gain were seen in cobalt chromium balloon-expandable stents compared to non-cobalt chromium stents (p=0.002 and p=0.002, respectively), stainless steel balloon-expandable stents (p=0.005 and p=0.005), and the S670 stent (p=0.069 and p=0.069). The size of stent used was not associated with risk of restenosis (p=0.756)., Conclusions: Cobalt chromium stents were associated with reduced restenosis, while smoking was associated with increased restenosis risk.

Background and Purpose: Delayed cerebral ischemia from vasospasm is a major complication after aneurysmal subarachnoid hemorrhage (SAH), but complications and/or low efficacy are associated with current therapy. We report our initial experience with intra-arterial use of a calcium channel blocker, nicardipine., Materials and Methods: A retrospective review of a consecutive series of patients with clinical and angiographic vasospasm treated with intra-arterial nicardipine was performed. Standard criteria for definition of significant, intractable vasospasm after aneurysmal SAH were used. After catheter angiographic confirmation of vasospasm, arteries showing severe narrowing were targeted for superselective catheterization. Nicardipine was infused at a high dose rate (0.415-0.81 mg/min). Contrast injections were performed at 2-5-mg intervals to assess effective response (a 60% increase in arterial diameter of the most severely decreased in caliber vessel compared with the very first angiographic run)., Results: Eleven consecutive patients underwent a total of 20 procedures; most had SAH with high Hunt and Hess grades (III or IV). All had depressed level of consciousness; others had paresis (7/20, 35%), aphasia (1/20, 5%), and facial nerve palsy (1/20, 5%). Between 10 and 40 mg of nicardipine was used. A 60% increase in diameter of the main affected artery compared with the initial diameter measured in the initial angiographic run was achieved in all procedures. Clinical improvement (resolved focal symptoms or increased Glasgow Coma Score) occurred in 10 of 11 patients (91%). One patient died from complications of the initial hemorrhage. No complications occurred after 16 of 20 procedures (80%); minor complications without sequelae occurred after the remaining procedures. Follow-up of at least 2 months in 10 survivors revealed minor or no deficits in most patients with a Glasgow Outcome Score of 1 or 2 in 9 of 10 patients (90%)., Conclusion: In this small series, high-dose intra-arterial nicardipine infusion to treat SAH-associated vasospasm seems to be safe and effective.

Examination of embolectomy using the Merci Retrieval System using experimental stroke models demonstrated that aspiration is not adequate to remove larger clots. The effectiveness of filter trapping was examined using the same models. A silicone model of the carotid artery system with model blood clot was incorporated in a laboratory pulsatile flow system. Embolectomy was performed using the Merci Retrieval System. Any clot not evacuated through the balloon guide catheter was trapped with a distal protection filter device developed for cervical stenting. The clot could not be sucked into the guide catheter by the recommended procedures in nine of 15 trials. Trapping failed in only one trial, in which the clot passed through a gap between the edge of the filter orifice and the inner model lumen. A clot was withdrawn to the catheter tip trapped across the edge of the orifice frame in one trial, and a very large clot was trapped across the filter orifice in two trials. Even clots made by the same method showed variation in properties, especially hardness, which may affect the effectiveness of aspiration. The aspiration procedure recommended for the Merci Retrieval System did not remove the large clots formed by embolectomy. The trapping procedure using a filter device without an orifice frame was effective to solve this problem.

Object: Tumors originating in the vertebrae in children are difficult to treat. In this paper the authors sought to evaluate the decision-making process and outcome of surgical intervention in this population given the complex issues of spinal stability, continued skeletal growth, intraoperative blood loss, and long-term outcome., Methods: To select patients for this study, the authors retrospectively reviewed medical records and images at the University of Iowa Hospitals and Clinics between 1996 and 2005. Their inclusion criteria were age younger than 18 years at the time of diagnosis and histopathological findings confirming that the tumor originated from vertebral bone. Sixteen patients met these requirements. In addition, the authors conducted a comparison with 45 patients in whom similar diagnoses were made prior to 1996. Gross-total resection of all nonmetastatic primary bone tumors is desired, as exemplified in 11 patients in this series; biopsy sampling only was performed in two others. Gross-total resection was also not performed in three patients with eosinophilic granuloma (EG). These three patients underwent nonsurgical treatment, which is different from how patients with EG were treated in the earlier study. Nine histopathological diagnoses were included; with a mean follow-up period of 3.7 years, the survival rate is 94%. The tumor recurred in one patient with a giant cell tumor of the sacrum. The authors performed preoperative tumor embolization and found that it was a useful adjunct to resection. Provocative testing prior to embolization was part of the protocol to reduce ischemic complications. Motion-sparing surgical procedures were performed in which a few segments were fused, preserving axial mobility., Conclusions: Overall, early intervention offers the best symptomatic relief, which can only be rendered if sufficient clinical suspicion provokes early diagnostic imaging.

The Merci Retriever is the first device for mechanical embolus removal in patients with cerebral ischemia. Use of the device was evaluated using experimental models. Three stroke model systems were created: silicone embolism model with flow system, pig embolism model, and silicone-pig tortuous artery model. The series of extraction procedures (capture, retrieval, and aspiration) was examined in the models under flow control. Coagulated blood clot was adopted as embolic material, to simulate embolic stroke of the carotid or middle cerebral arteries. Retrieval of the clot was successful in only one of six trials in the silicone model of the carotid artery, as the clot easily worked free from the helical tip. Aspiration was successful in three of the six trials. Retrieval was successful in two of four trials in the middle cerebral artery and aspiration was successful in two. Retrieval was successful in all five trials in the pig embolism model, and three of five trials in the silicone-pig tortuous artery model. The Merci Retriever does not always retain the embolism, and the helix tends to distort in acute or rough lumen. Aspiration is not always successful.

For better understanding of relevant morphology and mechanics, direct visualization of a Neuroform microstent (NFM) within an actual human intracranial artery is essential. Twelve NFM were deployed into 8 various segments of formaldehyde-fixed cadaver intracranial arteries. The arteries were then dehydrated and cleared in methyl salicylate to create transparency. The morphology of NFM was studied by digital macro-photography with a back illumination system. The possible limitations and important findings of the NFM were discussed.

Moyamoya syndrome is the secondary form of intracranial arterial occlusive diseases that produces collateral vessels from the base of brain. We report a case of Moyamoya syndrome developing in association with Graves thyrotoxicosis; as a result of its rapid progression and severe global ischemia, it was ultimately fatal. Because of the rarity of this association, we reviewed the literature in an attempt to establish possible demographic and clinical characteristics that may suggest putative mechanisms of pathogenesis.

Silicone models of cerebral aneurysm and stroke pathology were produced by copying the images of clinical cases to evaluate the simulation of endovascular procedures. Conventional silicone models, silicone suture models made from separate aneurysm sac and parent artery sutured together, and animal vascular models made from vessels obtained from pigs were made. The models were incorporated in the training system for simulation of endovascular procedures under digital subtraction angiography control using a portable angiography system. The conventional silicone models provided very close reproduction of the aneurysm and vessels, even the fine branches. However, greater resistance or impact was felt, especially when passing the device through curved vessels. Stroke models were insufficiently dilated by percutaneous transluminal angioplasty or stenting. The silicone suture model was useful to avoid damage to models of giant aneurysm or models with small orifices during the lost wax procedure, whereas the projection of domes was somewhat inaccurate. The animal vascular model could not provide accurate aneurysm shape and vessel diameter, although the feel during manipulation was much more realistic.

Various diseases of the carotid artery are treatable by stenting. However, few reports of overlapping carotid stents exist. As a result, the indications, long-term outcomes, and potential complications of this technique remain largely unknown. We therefore present and examine a series of 11 patients treated by this unique stenting method. A retrospective single-institution review was performed for patients in whom overlapping carotid stents were placed. Only patients with imaging follow-up beyond 3 months were included. Of 38 patients who had extracranial carotid artery stents placed, 11 patients fulfilled the inclusion criteria for both overlapping stents and imaging follow-up greater than 3 months (range, 0.4-3 years; mean, 1.3 years). Clinical follow-up ranged between 0.4 and 3.6 years (mean, 2.1 years). Carotid pathology within this cohort included atheromatous stenosis (n = 3), recurrent stenosis following carotid endarterectomy (n = 2) or stenting (n = 1), postirradiation angiitis (n = 1), carotid artery kink created by initial stent placement (n = 2), and both traumatic (n = 1) and neoplastic (n = 1) carotid blowout syndrome. No permanent stroke or stenting-related death occurred. Focal stenosis or intimal hyperplasia resulting in 35% or less luminal narrowing developed in three patients (27%) after tandem stenting. Overlapping stents provide a durable treatment for a variety of extracranial carotid pathologies. Clinically and hemodynamically significant (> 50%) poststenting stenosis or intimal hyperplasia did not occur in this series., (Copyright 2004 Wiley-Liss, Inc.)

To our knowledge, the use of transdermal nitroglycerin ointment (Nitropaste) in the setting of intracranial vasospasm has not been described in the peer-reviewed literature. Five patients with intracranial vasospasm induced by subarachnoid hemorrhage were evaluated angiographically both before and after application of Nitropaste. All cases exhibited mild to moderate improvement in the degree of vasospasm. We conclude that Nitropaste is a simple noninvasive technique to reduce intracranial vasospasm.

Background and Purpose: Permanent balloon occlusion (PBO) of the carotid artery has been previously shown to be an effective means to treat carotid blowout syndrome (CBS). However, despite the effectiveness of this endovascular technique, concern remains regarding its potential for producing delayed cerebral ischemic complications in 15% to 20% of patients. This significant limitation of carotid PBO led our group to evaluate an alternative management strategy, consisting of endovascular reconstruction of the carotid artery (ERCA) in patients thought to be at particularly high risk for carotid occlusion (ie, provocative balloon test occlusion, angiographic documented incomplete circle of Willis, or contralateral carotid artery occlusion)., Methods: We reviewed all cases of CBS referred to our service, in which ERCA was chosen as a management strategy for patients thought to be at high risk for PBO, based on previously defined criteria., Results: Sixteen carotid blowout events occurred in 12 patients with CBS who were deemed to be at high risk for cerebral ischemic complications, which were managed with ERCA by using a variety of stent devices and techniques. Adjunctive embolization of carotid pseudoaneurysms was performed in five of these patients by using platinum coils or acrylic glue. Hemostasis was achieved in all cases, although one patient with traumatic CBS and three patients with aggressive head and neck cancer-related CBS, required retreatment with ERCA. Recurrent CBS rates were similar to those reported in other studies using PBO. Overall, no treatment-related strokes or deaths occurred., Conclusion: CBS managed with ERCA can be performed safely and with efficacy of outcomes at least equivalent to those previously reported in association with conventional carotid PBO, therefore representing an excellent alternative endovascular technique for patients who are at increased risk of stroke after PBO.

The authors report a case in which the clinical and neuroimaging findings were initially considered diagnostic of a brainstem glioma. Angiography revealed a deep venous system (galenic) dural arteriovenous fistula causing brainstem interstitial edema. Successful endovascular surgery resulted in complete clinical recovery of the patient and resolution of the structural abnormalities that had been observed on magnetic resonance images. The neuroimaging and therapeutic significance of this case are discussed.

Background and Purpose: Although commonly acknowledged as paramount in significance, the mechanics of cyanoacrylate polymerization remain poorly characterized and quantified for clinical applications. This prompted development of a simplistic model for the systematic study of polymerization and binding behaviors of cyanoacrylates., Methods: A sliding bed apparatus was constructed that linked a strain gage with a vessel that could be filled with liquid medium, cyanoacrylate, and a microcatheter. As the cyanoacrylate polymerized, the microcatheter was mechanically drawn away very slowly from the fixed vessel, resulting in the development of forces that were recorded to characterize the dynamics of polymerization and binding. Optimization of the model required manipulation of several variables that could influence polymerization. Three different formulations of cyanoacrylate were also tested to determine whether there are significant differences in polymerization dynamics., Results: After experimenting with a few basic physical parameters of the test apparatus, consistent measurements of binding forces during cyanoacrylate polymerization could be recorded and measured. Polymerization produced a multiphasic pattern of binding forces, in which three distinct phases were observed. Furthermore, the rates of polymerization were significantly influenced by a variety of parameters, including the type of fluid within the model vessel, geometry of the model vessel, and rate of injection of acrylic into the well. Furthermore, there were significant differences in the pattern of dynamic binding forces among the various formulations of cyanoacrylate tested., Conclusions: A standardized bench top testing apparatus has been developed, which can consistently show dynamic binding related to polymerization of cyanoacrylates. This preliminary study shows a clear multiphasic pattern of polymerization binding, which may have important clinical implications. The apparatus may be useful for gaining better insight into a variety of clinically important phenomena related to cyanoacrylate polymerization.

Objective and Importance: To describe the clinical presentation and endovascular management of peripheral aneurysms of the lateral posterior choroidal artery. Aneurysms in this location are exceptionally rare and optimal treatment may be difficult., Clinical Presentation: Two patients with peripheral aneurysms of the distal portion of the lateral posterior choroidal artery presented with headaches from extensive intraventricular hemorrhage., Intervention: Endovascular surgical therapy by use of superselective n-butylcyanoacrylate embolization of the aneurysm and adjacent distal parent artery was successful in both patients., Conclusion: Patients with peripheral aneurysms of the lateral posterior choroidal artery usually present with intraventricular hemorrhage. They may be difficult to treat by open surgical techniques owing to their intraventricular location and the frequent inability to preserve the parent artery by aneurysm clipping. Instead, it is typical that either proximal parent artery occlusion or aneurysm trapping must be used. An equivalent endovascular surgical technique may be an attractive alternative method of management.

Objective: To report two cases of cerebral venous sinus thrombosis with papilledema and visual loss that improved after endovascular stent placement., Materials and Methods: Retrospective case series from a tertiary ophthalmic center., Results: Two cases of venous sinus occlusion treated with angioplasty and stenting are described. Both cases experienced improvement in optic disc edema and visual function following the procedures., Conclusion: Endovascular stent placement may relieve increased intracranial pressure and papilledema caused by cerebral sinus thrombosis and may prevent further visual loss.

Until recently, stroke preventive strategies have focused on either medical regimens aimed at antagonizing or reversing atherosclerosis, or surgical intervention for revascularization of the cerebrovascular system. However, with the advent of rapidly emerging microcatheterization techniques and technology, endovascular surgical revascularization of the brain is rapidly emerging as a powerful therapeutic modality. In particular, significant advances already have been made in revascularization of the extracranial carotid artery and many common anatomic sites of intracranial athero-occlusive disease, using special adaptations of conventional percutaneous angioplasty and stenting techniques. This paper reviews the cumulative experience with these emerging techniques, with a particular emphasis on clinical outcomes and future directions. It also reports the substantial cumulative institutional experience of the authors over the past 18 months with both extracranial carotid and intracranial artery stent-assisted carotid angioplasty.

Object: The goal of this study was to investigate the impact of the introduction of the Guglielmi detachable coil (GDC) therapeutic option on the overall management outcome of intracranial aneurysms. The authors accomplished this by assessing patient morbidity and mortality, inflation-adjusted hospital charges, lengths of stay in the hospital and the intensive care unit (ICU), and treatment efficacy., Methods: The authors conducted a retrospective analysis of consecutive cases of intracranial intradural aneurysms managed by a single multidisciplinary neurovascular team at a tertiary care, academic referral center during the 24 months preceding the introduction of the GDC procedure (Group I or pre-GDC era, 77 patients) and during the first 24 months after its introduction (Group II or GDC era, 99 patients). Treatment with GDCs was considered for cases of higher clinical grade or poor surgical risk, or in response to patient preference (27 [27%] of 99 patients in Group II). Host and lesion parameters in our cohort were validated against outcome parameters by using univariate and multivariate analyses. The pre-GDC and GDC subgroups of patients were comparable for major disease severity parameters (patient age, lesion location, clinical grade, and hemorrhage severity). There was no significant difference in clinical outcome at 6 months, infarcts on computerized tomography scanning, or aneurysm obliteration rates before and after introduction of GDC treatment. Decreasing trends in duration of hospital and ICU stay and in inflation-adjusted hospital charges occurred well before and thus were unrelated to the introduction of the GDC therapeutic option., Conclusions: The results of this study do not demonstrate any significant impact of integration of the GDC modality on clinical outcome, mortality, morbidity, or effectiveness of treatment. Ongoing improvements in hospital charges and length of hospital stay appeared unrelated to the introduction of the GDC option.

Primary Ewing's sarcoma (ES) of the spine is uncommon, exhibiting a variety of appearances on plain-film radiographs and cross-sectional images. We report the unusual CT imaging manifestations of a primary ES with a coarse trabecular pattern that mimicked an aggressive hemangioma of the cervical spine.

Capillary malformations or telangiectasias of the brain usually exhibit a benign clinical course, although occassionally they may be associated with mild to moderate symptomatology of uncertain origin. We report a case of an exceptionally aggressive capillary telangiectasia in a child, which was associated with progressive neurologic deterioration resulting in death.

Objective and Importance: Although conventional superselective chemical thrombolysis is frequently successful for the treatment of severe acute dural sinus thrombosis, the technique has limitations and risks. This prompted us to develop a supplemental technique for achieving more rapid recanalization, using coronary microballoon percutaneous transluminal angioplasty catheters. We describe a successful application of this technique and technology that has not been previously reported., Clinical Presentation: After several days of severe headaches, photophobia, and vomiting, a 29-year-old woman presented with rapidly progressive neurological deficits secondary to complete occlusion of the superior sagittal sinus (SSS) and right transverse/sigmoid sinus complex. Owing to her rapid neurological decline, she was referred for emergency endovascular intervention., Technique: Initially, superselective chemical thrombolysis of the SSS was performed using urokinase. However, because of the extensive nature of the thrombus and lack of initial therapeutic response, we elected to attempt mechanical thrombolysis with various coronary percutaneous transluminal angioplasty microballoon catheters. This was accomplished by initial coaxial positioning of the device into an occluded segment, followed by gentle inflation and retraction of the device along the course of the right transverse sinus and/or SSS. These maneuvers were repeated with balloons of increasingly large diameter. Near-complete restoration of venous outflow was obtained within the SSS with preferential runoff into the left transverse sinus. The right transverse sinus was only partially recanalized. Despite the patient's rapid neurological decline on presentation, she experienced a dramatic clinical recovery with near-complete reversal of neurological deficits within 24 hours of intervention., Conclusion: This report shows the feasibility of performing safe and effective mechanical thrombolysis with percutaneous transluminal angioplasty coronary balloon microcatheters within the major dural sinuses. This technique can probably accelerate clot disruption and thrombolysis, possibly resulting in a more rapid restoration of venous flow.

Background and Purpose: To our knowledge, recurrent carotid blowout syndrome (rCBS) has not been well described. Our purpose was to review our institution's recent experience with patients who presented with multiple episodes of carotid blowout syndrome (CBS), and who were referred for emergent diagnostic angiography and endovascular therapy., Methods: We retrospectively reviewed the last 46 consecutive patients who had a clinical diagnosis of CBS. All patients were examined and treated prospectively according to a standardized protocol. Most patients (43 of 46) had undergone extensive primary and salvage radical surgery with intraoperative brachytherapy or external beam radiation or both. The remaining three patients had either traumatic or iatrogenic CBS., Results: Twelve patients (26%) in our series had more than one episode of CBS in which a total of 32 (20 recurrent) events were observed (average 2.7, range 2-4). Intervals of rCBS ranged from 1 day to 6 years. Thirteen (65%) of 20 recurrent events were attributed to progressive disease (PD), and seven (35%) of 20 to treatment failures (TFs). In the PD group, seven (54%) of 13 had recurrent ipsilateral disease, and six (46%) of 13 had recurrent contralateral disease. Etiologies of rCBS were as follows: seven exposed carotids; seven carotid pseudoaneurysms; eight small-branch pseudoaneurysms; five tumor hemorrhages; three hyperemic/ulcerated wounds; and one aortic arch rupture. Twenty-seven of 32 events were treated with endovascular therapy, which included the following: nine carotid occlusions; 11 small-branch embolizations; three transarterial tumor embolizations; one carotid stent; and two direct-puncture embolizations. Four of six TFs were retreated successfully with endovascular therapy; the remaining two TFs were managed successfully by surgery. In the PD group, hemorrhagic complications of rCBS were managed successfully in all but one patient, who died. No permanent neurologic or ophthalmologic complications occurred., Conclusion: Recurrent CBS is a frequently encountered problem in which most cases are caused by PD resulting from both multifocal iatrogenic arteriopathy and occasional wound complications that are characteristic of aggressively managed head and neck surgical patients. Initial TFs are encountered often as well. Despite the diagnostic and therapeutic challenges of rCBS, most cases can be retreated effectively.

Background and Purpose: There are a variety of embolization applications for non-adhesive, liquid agents. We reevaluated the potential microvascular angiotoxicity of superselective infusions of dimethyl sulfoxide (DMSO) using very long infusion rates in a previously described animal model., Methods: Twenty-six swine underwent percutaneous femoral puncture for superselective catheterization of the artery of the rete while being continuously monitored for ECG and intraarterial pressure. Two volumes (0.5 or 0.8 mL) and three durations (30, 60, and 90 seconds) of superselective infusion of DMSO were used to evaluate the effect of a single-dose rate within an ipsilateral rete. Contralateral control infusions of normal saline were also administered. Acute hemodynamic and angiographic outcomes were assessed. After recovery, follow-up angiography and sacrifice were performed at either 10 or 28 days. Brains and retia were harvested for gross and microscopic histopathologic evaluation., Results: No significant hemodynamic alterations occurred acutely. Twenty-three of the 24 infused retia showed variable acute vasospasm that typically was mild to moderate in severity and transient (10 to 20 minutes). Follow-up angiography at sacrifice always showed normal retial arterial anatomy. No adverse clinical sequelae were noted. Gross inspection of brains showed no evidence of infarction or subarachnoid hemorrhage. Microscopic histopathologic examination of retia showed mostly nonspecific changes in both exposed and control samples. Possible causal histotoxicity was seen in four retia (three of four exposed to higher dose rates), in which involvement was limited to one to three retial arteries., Conclusion: Lower total dose and dose rates of superselective infusion of DMSO into the retial microarterial network resulted in substantially less angiotoxicity than that found in a previous study, as defined by clinical, angiographic, gross, and histopathologic criteria.

We report a case of pigmented villonodular synovitis involving the temporomandibular joint that presented as a rapidly growing tumor with extension through the skull base into the middle cranial fossa. The case is of interest not only because of the unusual extensive infiltration of this tumor but also because of the role modern diagnostic imaging and endovascular therapeutic techniques played in its diagnosis and management.

Objectives: The precise effects of therapeutic occlusion of the internal maxillary artery (IMA) on distal nasal mucosal perfusion are unknown. A better understanding of these effects has important implications regarding the rationale and expected efficacy of certain therapeutic interventions for epistaxis management. The authors developed an animal model to assess these issues., Study Design: The effects of "proximal" and progressively more "distal" occlusions of the IMA on nasal mucosal blood flow (NBF) were assessed in anesthetized swine using continuous laser Doppler flowmetry. The levels of arterial occlusion were selected to simulate clinical therapeutic occlusions used for the management of epistaxis., Methods: Nineteen swine were entered into one of four experimental groupings: proximal IMA occlusion using platinum micro-coils (n = 6), mid-grade distal IMA occlusion with polyvinyl alcohol particulate (PVA) suspensions (300 to 500 microns, n = 5), high-grade distal IMA occlusion with polyvinyl alcohol particulate suspensions (50 to 150 microns, n = 5), and sham control (n = 2)., Results: All embolizations resulted in acute decreases in average NBF from 120 mL/min per 100 g to 40 mL/min per 100 g (P < .05 for all groups). NBF returned to baseline in all three treated groups within 2 to 8 days after therapeutic embolization, depending on the level of occlusion (coils, 2 d; mid-grade PVA, 2-3 d; high-grade PVA, 8 d). Follow-up angiography showed recanalization and collateralization as possible methods of reestablishing NBF., Conclusions: This study supports the rationale for performing distal IMA occlusion with transarterial particulate embolization, in order to provide a longer period of time of diminished NBF. This theoretically should promote hemostasis within an injured portion of the nasal mucosa by decreasing perfusion pressure within the capillary bed. However, the benefits of distal IMA embolization must be balanced against potential ischemic complications, as may be more commonly seen with high-grade particulate embolization.

Summary: We report an unusual case of precipitous worsening of vasospasm associated with subarachnoid haemorrhage that developed during endosaccular coil embolisation of a ruptured posterior communicating aneurysm. The acutely worsening vasospasm occurred in the distal ipsilateral anterior circulation remote from the site of microcatheter manipulation, resulting in transient occlusion. Despite successful endovascular treatment of both the aneurysm and vasospasm, the patient continued to clinically decline and eventually died. This case raises important issues regarding the potential mechanisms and optimal therapeutic strategies for this complication, which are reviewed.

Summary: After undergoing prior partial surgical clipping of an acutely ruptured internal carotid aneurysm, a 29-year-old woman was referred for endovascular treatment of the gradually enlarging aneurysm remnant. The aneurysm had a somewhat peculiar ellipsoid configuration due to placement of the clip, with the largest dimension measuring less than 4 mm, and the neck measuring approximately 2 mm. Using the conventional endosaccular coil embolisation technique, two small electrolytically detachable coils were carefully folded into the aneurysm sac to produce excellent tight packing. However, immediately after detachment,a loop of the second coil inadvertently herniated out of the aneurysm into the center of the parent artery, exhibiting substantial pulse synchronous displacement. This created a potentially unstable situation for the remaining coils within the embolised aneurysm. To correct this problem we attempted to reposition the loop into the aneurysm using a modification of the previously described neck plastic technique. This technique succeeded without untoward complication. Although there are theoretical risks and limitations, the modified neck plastic technique may be useful in selective cases of inadvertent coil misplacement during endosaccular coil embolisation of aneurysms with the GDC system.

Background: It is difficult to predict which patients will tolerate occlusion of the internal carotid artery. This difficulty arises primarily because of uncertainties in the prediction of the adequacy of collateral circulation. Because of these uncertainties, balloon test occlusion and other methods have been developed to determine a priori the safety of carotid occlusion. However, all the methods are associated with significant false-positive and false-negative rates, as well as other neurologic complications. Because of these problems, more accurate and less invasive methods for predicting tolerance of carotid occlusion are needed., Methods: In this report, we present the initial clinical evaluation of a new method for assessing the collateral circulation aided by a mathematical model of the cerebral vasculature. Data from the angiograms of 14 patients who underwent carotid endarterectomy were used to create individualized simulations of their cerebral circulations. As a test of the accuracy of the simulations, we compared values of the intracarotid stump pressures predicted by the model to those measured at surgery during the period of carotid occlusion., Results: The pressure predictions of the model correlated well with those measured at surgery. Linear regression analysis of measured versus predicted values yielded a line with slope 1.05. The line with slope 1.00, which denotes perfect agreement between predictions and measurements, is within the 95% confidence interval of the slope determined from the regression analysis., Conclusions: Mathematical models of the cerebrovascular circulation can provide good predictions of intravascular pressure in the collateral circulation, and may provide accurate predictions of the flow as well. The present study reveals several areas that need further development, such as the models of the microvasculature, measurement of the arterial dimensions from angiograms, and consideration of other collateral sources such as the leptomeningeal and retrograde ophthalmic sources of flow. Incorporation of these improvements may lead to a clinically useful, noninvasive assessment of the state of the cerebrovascular collateral circulation in the individual patient.

Background: Extensive experience and critical evaluation of the efficacy of a pharmacologic hypotensive challenge during conventional balloon test occlusion (BTO) of the internal carotid artery (ICA) is lacking. This prompted us to review our institution's most recent experience with this adjunctive provocative test before planned therapeutic balloon occlusion of the ICA., Methods: Twenty consecutive cases of endovascular therapeutic balloon occlusion of the ICA were retrospectively reviewed. Conventional BTO under normotension and with hypotensive challenge were performed within a standardized protocol., Results: Sixteen patients underwent provocative testing, of which 13 had BTO with hypotensive challenge. All patients in this group tolerated these maneuvers without acute neurologic deficit. Two (15%) of these patients developed delayed permanent neurologic deficits, which seemed to be attributable to hemodynamic ischemia. One of seven patients not undergoing hypotensive challenge also developed transient neurologic deficits after carotid occlusion., Conclusions: Despite the conceptually attractive and early positive experience of the hypotensive challenge in attempting to increase sensitivity and specificity of risk for developing delayed hemodynamic ischemia, we have found two significant false-negative results. This experience is reviewed in the context of risks of permanent balloon occlusion of the carotid artery after balloon test occlusion.

A statistical model for characterizing the erratic nature of aneurysm evolution is developed and tested. This model is based upon a multiplicative hypothesis, whereby it is theorized that the progressive changes in the size of a given aneurysm are determined by random multipliers. Such a model would predict that within a large population of aneurysms, a lognormal histogram for aneurysm sizes would occur (i.e. the logarithms of aneurysm size would have a normal distribution). When applied to previously published clinical data of unruptured aneurysms by Crompton (1966) and McCormick et al. (1970), the model is found to adequately describe both sets of data. The methods introduced in this paper illustrate the utility of incorporating statistical and clinical insights with fundamental biometry for studying the complex phenomena of aneurysm growth and rupture.

Summary: While receiving optimal antibiotic therapy for subacute bacterial endocarditis (SBE), a teenage girl with mild congenital mitral insufficiency presented with two separate episodes of subarachnoid haemorrhage from two rapidly evolving metachronous mycotic aneurysms within the vertebrobasilar circulation. Both aneurysms were successfully treated by endovascular coil embolisation with the GDC system. This permitted at the minimum, successful amelioration of the short term risk of rerupture of the aneurysms, and facilitated operative management of the patient's infected mitral valve. The case further illustrates the utility and effectiveness of endovascular therapy for managing not only the neurovascular sequelae of SBE, but also perhaps the enhanced ability to optimally manage the source of mycotic aneurysms. In addition, the potential limitations and risks of this therapeutic strategy are assessed.

Purpose: To determine the association of cerebral arterial anomalies and progressive cerebral arterial occlusive disease in infants with facial hemangiomas., Materials and Methods: The cases of eight infants (seven girls and one boy) with the diagnosis of cervicofacial hemangioma and intracranial arterial anomalies were reviewed retrospectively. Findings from clinical and imaging examinations--including cranial computed tomography, magnetic resonance imaging and angiography, and catheter angiography--were evaluated. Serial imaging findings were studied to document progressive intracranial vascular changes., Results: Five patients had additional associated congenital anomalies. Seven were treated with corticosteroids, interferon alfa-2a, or both. Progressive cerebrovascular occlusive changes were documented in four of the seven patients with serial imaging findings. Four other patients (all treated pharmacologically) had MR imaging documentation of cerebral infarction, and all had consistent, acquired neurologic symptoms., Conclusion: Intracranial arterial anomalies can coexist with cervicofacial hemangioma. Aneurysmal and occlusive changes are potentially progressive and can result in cerebral infarction. A causative association between occlusive cerebrovascular disease and pharmacologic treatment has not been excluded.

We report a difficult case of recurrent carotid blowout syndrome in a patient who had a rupture of the common carotid artery with formation of a large pseudoaneurysm. Conventional management of this emergency, consisting of composite occlusion of the internal and common carotid arteries, was not possible owing to prior clinical failure of balloon test occlusion. This led to an initial attempt to cover the site of rupture with overlapping self-expanding stents, which was only temporarily successful in controlling the hemorrhage. When a subsequent episode of carotid rupture with life-threatening hemorrhage occurred, percutaneous direct-puncture acrylic embolization with temporary flow arrest was used to successfully obliterate the pseudoaneurysm.

The ability to systematically and meaningfully classify a disease is in many ways a reflection of our overall understanding of it. Over time, nosologic schemes applied to any disease typically undergo a characteristic evolution from purely descriptive, to pathoanatomic and/or embryologic, to finally biological definitions. With the recent developments in further elucidating the pathophysiology, histopathology, natural history, and cellular biology of various vascular malformations occurring within the central nervous system, it is time to derive a more comprehensive and "universal" classification system that integrates classic pathoanatomic schemes with a biologically defined scheme previously developed for systematic vascular malformations. Such a system is proposed and discussed, including detailed review of important subtypes.

Purpose: Our goal was to describe the prevalence and types of cerebral vascular malformations (CVMs) seen with MR imaging in patients with hereditary hemorrhagic telangiectasia (HHT)., Methods: We reviewed retrospectively the brain MR images of 184 consecutive patients with HHT. Catheter angiography was performed in 17 patients with CVMs detected on MR images., Results: MR imaging revealed 63 CVMs in 42 patients. Classic arteriovenous malformations (n = 10) had a conspicuous network of vessels with flow voids and enlarged adjacent pial vessels. Apparent venous malformations (n = 5) were best seen after administration of contrast material as a prominent vessel coursing through normal brain parenchyma. Indeterminate vascular malformations (n = 48) had a spectrum of appearances characterized by variable combinations of heterogeneous signal intensity, enhancement, or hemosiderin. Angiography in 17 patients revealed 47 CVMs. Forty-six were arteriovenous malformations (AVMs), including 25 CVMs not seen with MR imaging and 21 CVMs that by MR criteria included 8 AVMs and 13 indeterminate vascular malformations. Angiography confirmed 1 venous malformation seen with MR imaging but failed to detect 3 indeterminate lesions revealed by MR imaging., Conclusion: MR imaging of a large cohort of consecutive patients with HHT revealed a CVM prevalence of 23% (42/184). Most CVMs (48/63) have an atypical appearance for vascular malformations on MR images. Angiographic correlation suggests that MR imaging underestimates the prevalence of CVMs and that the majority of indeterminate CVMs, despite their variable MR appearance, are AVMs.

Objective: Since a simple, rapid and accurate stereotactic system allowing CT monitoring would offer the neurosurgeon several advantages, the feasibility and application accuracy of frameless laser-guided freehand point stereotaxis for neurosurgical interventions was studied., Methods: A Cartesian coordinate grid mounted upon the far wall of a CT scan room defined a plane. The scanner isocenter defined the origin of a three-dimensional coordinate system. Phantom entry point and target point coordinates were determined by the positional CT cursor. These coordinates were entered into a computer which determined the coordinates of the grid intersection point with a line passing through the entry and target points. A tripod-mounted laser assembly comprising two encased lasers oriented retrograde and antegrade along opposite vectors, was positioned near the grid. The retrograde laser was positioned to illuminate the marked grid intersection point while the antegrade laser simultaneously illuminated the entry point; the beams were thereby aligned along the line of trajectory. The tip of a probe was placed on the entry point; the hub was then moved into the path of the antegrade laser, thereby aligning the probe with the line of trajectory. The probe was then inserted to the target at a trigonometrically calculated distance., Results: Ten consecutive phantom tests averaged 17.5 min. Phantom test application accuracy averaged +/-2 mm at an average insertion distance of 7.1 cm., Conclusion: Phantom tests indicate that simple, rapid and accurate CT-monitored frameless laser-guided freehand point stereotaxis is feasible. Clinical investigation is warranted.