Histologic evaluation of platinum coil embolization in an aneurysm model in rabbits

PURPOSE

To characterize the histologic response to platinum coil embolization by using a rabbit aneurysm model.

MATERIALS AND METHODS

Saccular aneurysms were created in New Zealand White rabbits by using vessel ligation with intraluminal elastase incubation. Aneurysms were subsequently embolized by using platinum coils. Subjects were sacrificed at various intervals up to 12 weeks following coil embolization. The aneurysm cavities and adjacent vessels were embedded in methylmethacrylate, were sectioned, and were stained for histologic examination.

RESULTS

Two weeks following coil implantation, aneurysms were filled predominantly with unorganized thrombus. Six weeks following coil implantation, histologic features included complete filling of the aneurysm lumen with either prominent laminated but unorganized thrombus or areas of unorganized thrombus interspersed among areas of cellular infiltration. At 12 weeks following coil implantation, aneurysms were filled with the loosely packed, disordered cells contained within the extracellular matrix. Fibrosis or smooth muscle cell infiltration was not present in any of the 6- or 12-week samples.

CONCLUSION

Platinum coils placed into experimental saccular aneurysms in New Zealand White rabbits failed to elicit a fibrotic response. This model can be used for the testing of biologic modifications of platinum coils aimed at increasing intra-aneurysmal fibrosis.

In vivo endochondral bone formation using a bone morphogenetic protein 2 adenoviral vector

Bone morphogenetic proteins (BMPs) are polypeptides that induce ectopic bone formation in standard rat in vivo assay systems. Previous studies have demonstrated the clinical utility of these proteins in spinal fusion, fracture healing, and prosthetic joint stabilization. Gene therapy is also a theoretically attractive technique to express BMPs clinically, since long-term, regulatable gene expression and systemic delivery with tissue-specific expression may be possible in future. This study was performed to determine whether an adenoviral vector containing the BMP-2 gene can be used to express BMP-2 in vitro and promote endochondral bone formation in vivo. In vitro, U87 MG cells transduced per cell with 20 MOI of an adenoviral construct containing the BMP-2 gene under the control of the universal CMV promoter (Ad-BMP-2) showed positive antibody staining for the BMP-2 protein at posttransfection day 2. The synthesis and secretion of active BMP-2 into the conditioned medium of Ad-BMP-2-transduced 293 cells were confirmed by Western blot analysis and the induction of alkaline phosphatase activity in a W-20 stromal cell assay. In vivo, Sprague-Dawley rats and athymic nude rats were injected with Ad-BMP-2 in the thigh musculature and were sacrificed on day 3, 6, 9, 12, 16, 21, 60, and 110 for histological analysis. The Sprague-Dawley rats showed evidence of acute inflammation, without ectopic bone formation, at the injection sites. In the athymic nude rats, BMP-2 gene therapy induced mesenchymal stem cell chemotaxis and proliferation, with subsequent differentiation to chondrocytes. The chondrocytes secreted a cartilaginous matrix, which then mineralized and was replaced by mature bone. This study demonstrates that a BMP-2 adenoviral vector can be utilized to produce BMP-2 by striated muscle cells in athymic nude rats, leading to endochondral bone formation. However, in immunocompetent animals the endochondral response is attenuated, secondary to the massive immune response elicited by the first-generation adenoviral construct.

Percutaneous vertebroplasty in vertebral osteonecrosis (Kümmell's spondylitis)

The authors report the clinical symptoms and response to therapy of a series of patients who presented with subacute or chronic back pain due to vertebral osteonecrosis (Kümmell's spondylitis) and who underwent percutaneous vertebroplasty.

The authors performed a retrospective chart review of a series of 95 patients in whom 149 painful, nonneoplastic compression fractures were demonstrated and who were treated with percutaneous transpediculate polymethylmethacrylate (PMMA) vertebroplasty. In six of these patients there was evidence of vertebral osteonecrosis, as evidenced by the presence of an intravertebral vacuum cleft on radiography or by intravertebral fluid on magnetic resonance (MR) imaging. Clinical and radiological findings on presentation were noted. Technical aspects of the vertebroplasty technique were compiled. Response to therapy, defined as qualitative change in pain severity and change in level of activity, was noted immediately following the procedure and at various periods on follow-up reviews.

One man and five women, who ranged in age from 72 to 90 years (mean 81 years), were treated. Each patient had one compression fracture. The fractures were at T-11 (one patient), L-1 (two patients), L-3 (two patients), and L-4 (one patient). The pain pattern was described as severe and localized to the affected vertebra, and sometimes radiated along either flank. Pain duration ranged from 2 to 12 weeks, and the pain was refractory to conservative therapy that consisted of bedrest, analgesics, and external bracing. At the time of treatment, all patients were bedridden because of severe back pain. In all patients either plain radiographic or computerized tomography evidence of intravertebral vacuum cleft or MR imaging evidence of vertebral fluid collection consistent with avascular necrosis of the vertebral body was demonstrated. Four patients underwent bilateral transpediculate vertebroplasty, and two patients underwent unilateral transpediculate vertebroplasty. The fracture cavities were specifically targeted for PMMA injection. Additional fortification of the osteoporotic vertebral body trabeculae was also performed when feasible. "Cavitygrams" or intraosseous venograms with gentle contrast injection were obtained prior to application of cement mixture. In all patients subjective improvement in pain and increased mobility were demonstrated posttreatment. The follow-up period ranged from 4 to 24 hours after treatment. Two patients made additional office visits at 1 and 3 months, respectively.

Patients presenting with vertebral osteonecrosis (Kümmell's spondylitis) often suffer from local paraspinous or referred pain. When performing vertebroplasty on these patients, confirmation of entry into the fracture cavities with contrast-enhanced "cavitygrams" should be performed prior to injection of PMMA cement. The response to vertebroplasty with regard to amelioration of pain and improved mobility is encouraging.

The fate of neuroradiologic abstracts presented at national meetings in 1993: rate of subsequent publication in peer-reviewed, indexed journals

BACKGROUND AND PURPOSE

Abstract presentations are a valuable means of rapidly conveying new information; however, abstracts that fail to eventually become published are of little use to the general medical community. Our goals were to determine the publication rate of neuroradiologic papers originally presented at national meetings in 1993 and to assess publication rate as a function of neuroradiologic subspecialty and study design.

METHODS

Proceedings from the 1993 ASNR and RSNA meetings were reviewed. A MEDLINE search encompassing 1993-1997 was performed cross-referencing lead author and at least one text word based on the abstract title. All ASNR and RSNA neuroradiologic abstracts were included. Study type, subspecialty classification, and sample size were tabulated. Publication rate, based on study design and neuroradiologic subspecialty, was compared with overall publication rate. Median duration from meeting presentation to publication was calculated, and the journals of publication were noted.

RESULTS

Thirty-seven percent of ASNR abstracts and 33% of RSNA neuroradiologic abstracts were published as articles in indexed medical journals. Publication rates among neuroradiologic subspecialty types were not significantly different. Prospective studies presented at the ASNR were published at a higher rate than were retrospective studies. There was no difference between the publication rate of experimental versus clinical studies. Neuroradiologic abstracts were published less frequently than were abstracts within other medical specialties. Median time between abstract presentation and publication was 15 months.

CONCLUSION

Approximately one third of neuroradiologic abstracts presented at national meetings in 1993 were published in indexed journals. This rate is lower than that of abstracts from medical specialties other than radiology.

Experimental side-wall aneurysms: a natural history study

We studied the natural history of canine side-wall experimental aneurysms to determine the incidence of spontaneous aneurysm thrombosis, to serve as control data for future studies focusing on development of aneurysm occlusion devices. Bilateral common carotid artery vein patch aneurysms were surgically created in eight mongrel dogs (20-25 kg). Duplex Doppler sonography was performed at 14 days and angiography between 30 and 210 days following aneurysm creation. Sonography demonstrated patency of 13 (81%) of 16 aneurysms. Patent aneurysms ranged in size from 8 x 10 mm to 14 x 16 mm. Conventional angiography was performed in four dogs approximately 30 days following aneurysm creation; in these four, all of 7 initially patent on sonography remained fully patent. One dog underwent conventional angiography at approximately 60 days following aneurysm creation; both aneurysms in this case remained widely patent. Three dogs underwent conventional angiography at approximately 200 days following aneurysm creation; all 4 aneurysms initially patent on sonography remained fully patent. None of the three aneurysms found to be occluded on sonographs demonstrated spontaneous recanalization. The canine side-wall aneurysm model is a valid tool for testing some aneurysm-occlusion devices, because control aneurysms remain patent indefinitely.

Prevalence of cerebral aneurysms in patients with persistent primitive trigeminal artery

OBJECT

The aim of this study was to determine the prevalence of cerebral saccular aneurysms in patients with persistent primitive trigeminal artery (PPTA). The prevalence of cerebral saccular aneurysms in patients with PPTA previously has been reported to be 14 to 32%, but this rate range is unreliable because it is based on collections of published case reports rather than a series of patients chosen in an unbiased manner.

METHODS

The authors retrospectively evaluated their own series of 34 patients with PPTA to determine the prevalence of cerebral aneurysms in this population. The prevalence of intracranial aneurysms in patients with PPTA was approximately 3% (95% confidence interval 0-9%).

CONCLUSIONS

The prevalence of intracranial aneurysms in patients with PPTA is no greater than the prevalence of intracranial aneurysms in the general population.

Angiographic correlation of CT calcification in the carotid siphon

BACKGROUND AND PURPOSE

Calcification in the coronary arteries has been correlated with significant vessel stenosis. The predictive value of calcification within the carotid siphon has not been characterized; however, stenosis in the carotid siphon is potentially important in determining management of patients with ipsilateral carotid bifurcation stenosis. The purpose of this study was to determine optimal parameters for assessing carotid siphon calcification on head CT scans and to compare the CT findings with angiographic results.

METHODS

We performed a retrospective review of patients referred for diagnostic carotid arteriography. Those patients who also had undergone a head CT study at our institution were selected. The CT scans and angiograms of 64 patients (128 vessels) were reviewed. Carotid siphon calcification on CT scans was characterized on brain and bone windows as mild, moderate, or severe. Comparison was then made with angiographic findings.

RESULTS

The sensitivity and specificity of CT for depicting greater than 50% angiographic stenosis in the carotid siphon were 86% and 98%, respectively, for bone windows and 100% and 0%, respectively, for brain windows. The positive predictive value (PPV) for a stenosis of greater than 50% as evidenced by severe calcification was 86% on bone windows and 11% on brain windows. The PPV for mild and moderate calcification on bone windows was 2.5% and 0%, respectively.

CONCLUSION

Severe CT calcification in the carotid siphon as characterized on bone windows correlates with a carotid siphon stenosis of greater than 50% as determined angiographically. Therefore, the identification of severe calcification offers a potential noninvasive method for identifying stenosis of the carotid siphon. This information may be essential in determining management and prognosis for patients with carotid bifurcation stenosis.

Dural arteriovenous fistula of the cervical spine presenting with subarachnoid hemorrhage

We describe a case of dural arteriovenous fistula (DAVF) presenting with subarachnoid hemorrhage (SAH). The diagnosis of DAVF was based on spinal angiography. A review of the literature revealed that five of 13 previously reported DAVFs of the cervical spine were accompanied by SAH. SAH has not been observed in DAVFs involving other segments of the spinal canal.

Endovascular treatment of ruptured, peripheral cerebral aneurysms: parent artery occlusion with short Guglielmi detachable coils

We report two cases of distal cerebral aneurysms that were treated by parent artery occlusion with short Guglielmi detachable coils (GDCs). One patient had a presumed mycotic aneurysm of the distal left posterior cerebral artery, and the other had a partially clipped aneurysm of the distal right anterior inferior cerebellar artery that had hemorrhaged. Short GDCs allow controlled, accurate occlusion of the parent artery at the aneurysmal neck.

Exposure of medical personnel to methylmethacrylate vapor during percutaneous vertebroplasty

The occupational exposure to methylmethacrylate (MMA) vapor during percutaneous vertebroplasty was determined. During five vertebroplasty procedures, air-sampling pumps were attached to medical personnel. MMA vapor levels in the samples were then quantified using gas chromatography. The samples collected yielded MMA vapor levels of less than five parts per million (ppm). The MMA vapor concentrations measured were well below the recommended maximum exposure of 100 ppm over the course of an 8-hour workday.

Percutaneous spinal fusion using bone morphogenetic protein-2 gene therapy

OBJECT

Gene therapy has many potential applications in neurosurgery. One application involves bone morphogenetic protein-2 (BMP-2), a low-molecular-weight glycoprotein that induces bone formation in vivo. Numerous studies have demonstrated that the BMP-2 protein can enhance spinal fusion. This study was undertaken to determine whether direct injection of an adenoviral construct containing the BMP-2 gene can be used for spinal fusion.

METHODS

Twelve athymic nude rats were used in this study. Recombinant, replication-defective type 5 adenovirus with the cytomegalovirus (CMV) promoter and BMP-2 gene (Ad-BMP-2) was used. A second adenovirus constructed with the CMV promoter and beta-galactosidase (beta-gal) gene (Ad-beta-gal) was used as a control. In three groups (four rats each) 7.5 microl of virus (5x10(8) particles/microl) was injected percutaneously and paraspinally at the lumbosacral junction: Group 1 received Ad-BMP-2 bilaterally; Group 2 received Ad-BMP-2 on the right, Ad-beta-gal on the left; and Group 3 received Ad-beta-gal bilaterally. Computerized tomography (CT) scans of the lumbosacral spine were obtained at 3, 5, 8, and 12 weeks. At 12 weeks, the animals were killed and underwent histological inspection. Ectopic bone formation was observed both on three-dimensionally reconstructed CT scans and histological examination in all rats at sites treated with Ad-BMP-2. Histological analysis demonstrated bone at different stages of maturity adjacent to the spinous processes, laminae, and transverse processes.

CONCLUSIONS

Results of this study clearly demonstrated that it is possible to produce in vivo endochondral bone formation by using direct adenoviral construct injection into the paraspinal musculature, which suggests that gene therapy may be useful for spinal fusion in the future.

Correlation of angiography and MR imaging in cerebral vasculitis

PURPOSE

MR imaging and cerebral angiography were correlated in patients with primary angiitis of the central nervous system (PACNS) to assess the relative roles of these imaging modalities in the diagnosis.

MATERIAL AND METHODS

In 9 patients, MR imaging and angiography were compared with regard to the relative involvement of each major vascular territory. Vascular territories assessed were the anterior, middle, and posterior cerebral arteries, and the posterior fossa.

RESULTS

All patients had angiographic findings consistent with vasculitis in multiple vascular territories. MR findings ranged from normal to diffusely abnormal. One patient had a completely normal MR investigation. Of 50 territories affected by vasculitis on angiography, 17 (34%) were normal on MR.

CONCLUSION

Relative to cerebral angiography, MR imaging is a poor indicator of the presence or absence of PACNS. Angiography is indicated when clinical suspicion of PACNS is strong, regardless of the findings on MR.

Effects of systemic heparinization on the thrombogenicity of hydrophilic and nonhydrophilic catheters in a swine model

We assessed the effect of systemic heparinization on the in-vivo thrombogenicity of various micro- and guiding catheters in a swine model. Microcatheters were placed through 6-F guiding catheters into the common carotid arteries of swine for 30-min (short-term) and 90-min (medium-term) periods, with and without systemic heparinization. At the end of the placement period the microcatheters were retracted through the guiding catheters and fixed for scanning electron microscopy (SEM). Guiding catheters were harvested after 5 h placement, with and without systemic heparinization, by retraction through 8-F sheaths and fixed for SEM. The surfaces of both hydrophilic and nonhydrophilic microcatheters all demonstrated more accumulation of debris during placement without than with systemic heparinization. The difference was primarily in the amount of fibrillary material on the catheter surface. The guiding catheters also demonstrated increased debris accumulation without systemic heparinization. This suggests that, even when using relatively nonthrombogenic catheters, systemic heparinization is indicated during cerebral angiography.

Frequency and significance of a small distal ICA in carotid artery stenosis

PURPOSE

Accurate calculation of the percentage of stenosis is crucial for identifying candidates for endarterectomy. Our goal was to quantify the reduction in diameter of the distal internal carotid artery (ICA) as a function of proximal ICA stenosis and to discuss the implications of distal ICA narrowing on the calculation of percentage of stenosis using the criteria of the North American Symptomatic Carotid Endarterectomy Trial (NASCET).

METHODS

We retrospectively reviewed the carotid angiograms of 81 patients referred for evaluation of carotid stenosis. The caliber of the ICA stenosis and the diameters of the normal distal ICA, the common carotid artery, and the internal maxillary artery were remeasured with precision calipers. The percentage of stenosis derived from the NASCET criteria were compared with vessel diameter and with the difference in size of the ipsilateral and contralateral distal ICAs. We then recalculated the percentage of stenosis by substituting the presumed normal contralateral distal ICA diameter for the ipsilateral distal ICA diameter.

RESULTS

In carotid arteries without significant stenosis (<70%), the distal ICA diameter measured 5.94+/-1.10 mm, but in vessels with severe stenosis (>70%), the distal ICA diameter measured 4.69+/-1.23 mm. After recalculation, four of 26 vessels were upgraded in classification from moderate (40% to 69%) to severe (>70%) stenosis.

CONCLUSION

The diameter of the distal ICA begins to decrease when the proximal stenosis is 60% or greater. If the ICA distal to a stenosis is smaller than the contralateral ICA, recalculating the percentage of stenosis by substituting measurements of the contralateral distal ICA diameter may be warranted.

In vivo evaluation of a new type I collagen hemostatic plug for high-risk, large-core biopsies

PURPOSE

To evaluate in a swine model the hemostatic properties of a new, expansile type I collagen plug for use in high-risk renal biopsies.

MATERIALS AND METHODS

Highly purified bovine type I collagen was formed into porous cylindrical plugs and compressed radially to fit into a 5-F delivery system. On hydration these collagen plugs demonstrated radial expansion with approximately 1,600% volumetric expansion ratio. Direct exposure of both kidneys was performed in a 25-kg swine, and a bolus of 3,000 U of heparin was administered to create a coagulopathic state. A 14-gauge Temno coaxial biopsy gun was utilized in performing nine pairs of renal biopsies. The first biopsy of each biopsy pair represented the control biopsy (without collagen plug placement), whereas the second biopsy of each pair represented the plugged biopsy. The presence and duration of hemorrhage from each biopsy site was monitored visually.

RESULTS

The biopsy sites without collagen plug showed immediate hemorrhage in nine of nine cases (100%), and in two of nine cases (22%) pulsatile bleeding was noted. With the use of the collagen plug, seven of nine (78%) sites showed immediate hemorrhage, but in no case was pulsatile bleeding noted. Mean bleeding duration was 156 seconds for the control biopsies versus 73 seconds for the biopsy sites plugged with collagen (P = .03, Mann-Whitney rank sum test). Bleeding duration was less than 1 minute in only one of nine (11%) control biopsies compared to six of nine (67%) collagen plug biopsies.

CONCLUSIONS

A recently developed, expansile collagen hemostatic plug significantly decreases the duration of hemorrhage at renal biopsy sites in an anticoagulated swine model.

Practice parameters in adults with suspected or known supratentorial nonoptic pathway low-grade glioma

Gene therapy has many potential applications in neurosurgery. One application involves bone morphogenetic protein-2 (BMP-2), a low-molecular-weight glycoprotein that induces bone formation in vivo. Numerous studies have demonstrated that the BMP-2 protein can enhance spinal fusion. This study was undertaken to determine whether direct injection of an adenoviral construct containing the BMP-2 gene can be used for spinal fusion. Twelve athymic nude rats were used in this study. Recombinant, replication-defective type-5 adenovirus with a universal promoter and BMP-2 gene (Ad-BMP-2) was used. A second adenovirus constructed with a universal promoter and beta-galactosidase (beta-gal) gene (Ad-beta-gal) was used as a control. Seven and one-half microliters of virus was injected percutaneously and paraspinally at the lumbosacral junction in three groups (four animals each): 1) Ad-BMP-2 bilaterally, 2) Ad-BMP-2 on the right, Ad-beta-gal on the left, and 3) Ad-beta-gal bilaterally. Computerized tomography (CT) scans of the lumbosacral spine were obtained at 3, 5, and 12 weeks. At 12 weeks, the animals were killed for histological inspection. Ectopic bone formation was seen both on three-dimensional CT reconstruction and histologically in all rats at sites treated with Ad-BMP-2. Histological analysis revealed bone at different stages of maturity adjacent to the spinous processes, laminae, and transverse processes. This study clearly demonstrated that it is possible to produce in vivo endochondral bone formation by using direct adenoviral construct injection into the paraspinal musculature, which suggests that gene therapy may be useful for spinal fusion in the future.

Platinum coil-mediated implantation of growth factor-secreting endovascular tissue grafts: an in vivo study

PURPOSE

To demonstrate in vivo that platinum embolic coils can be used to deliver genetically modified, growth factor-secreting fibroblast grafts into the endovascular space with the long-term goal of improving fibrosis within coil-embolized cerebral aneurysms.

MATERIALS AND METHODS

Murine fibroblasts that contained multiple inserts of the DNA for human basic fibroblast growth factor were grown in culture onto 10-mm-long segments of Guglielmi detachable coils. Control (n = 4) and fibroblast-bearing (n = 4) coils were implanted into the common carotid artery in nude rats. The arterial segments that contained the coil were harvested after 14 or 35 days. Cellular content and collagen formation in the treated vessels were assessed histologically.

RESULTS

At both 14 and 35 days, samples with control coils showed primarily involuting blood elements with minimal fibroblast proliferation or collagen formation. At 14 days, samples with fibroblast-bearing coils showed extensive fibroblast proliferation. At 35 days, samples with fibroblast-bearing coils showed marked interval fibroblast proliferation and collagen formation.

CONCLUSION

Platinum coils can be used as a cell delivery device. Direct intravascular implantation of growth factor-secreting fibroblast grafts leads to improved intravascular scar formation, therefore theoretically reducing the potential for aneurysm regrowth or coil compaction.

Transforming growth factor-Beta binds reversibly in vitro to guglielmi detachable coils

SUMMARY

We determined the propensity for and reversibility of transforming growth factor-beta(TGFbeta) binding to uncoated Guglielmi Detachable Coils (GDC) and to GDC coated with extracellular matrix (ECM) proteins. Three 1.0 centimetre samples each of uncoated GDC-18 and of GDC-18 coated with either poly-L-lysine, laminin, type I collagen, type IV collagen, fibronectin, or poly-L-lysine and laminin were prepared. These samples were immersed briefly in a solution containing I(125)-labelled TGFbeta at a concentration of 0.225 mug/ml with initial specific activity of 123.3 mCi/mg (DuPont-NEN, Billerica, MA), and were counted using a scintillation counter. Each sample was then placed in a vial containing saline, shaken for 60 seconds, and counted again. Selected samples were immersed for varying periods within the TGFbeta solution and counted before and after saline rinse. Samples were rinsed one week after initial rinsing and counted again. The amount of binding between coil types was compared using the Student t test. For all samples initial binding of TGFbeta was in the order of 60-120 pg/cm. For the pre-rinse data there were no statistically significant differences between the amount bound to any single coil coating type relative to other coatings. Compared to the initial accumulations, the amount remaining after rinsing ranged from 40% (poly-L-lysine) to 63% (poly-L-lysine with laminin), with a mean of 55% among the seven coil types. After rinsing there was more growth factor remaining on uncoated coils than on poly-L-lysine-coated coils (p=0.05), fibronectin-coated coils (p=0.01), and type IV collagen-coated coils (p=0.04). There was a trend toward greater residual growth factor on coils coated with poly-L-lysine and laminin compared to coils coated with poly-L-lysine alone (p=0.10). Delayed, second rinsing of the samples one week after initial testing demonstrated only minor incremental loss of TGFbeta from the coil surfaces. After five minutes of immersion, accumulation was approximately 200% greater than that noted with brief submersion, but immersions lasting over five minutes did not yield increasing levels of TGFbeta binding. TGFbeta binds to GDC coils. Binding is not improved with ECM protein-coated coils compared to uncoated coils. The absolute amount of TGFbeta bound to the coil will likely result in local concentrations of growth factor in the order of those required for biological activity in vivo.

Prevalence of cerebral aneurysms in patients with fibromuscular dysplasia: a reassessment

OBJECT

The aim of this study was to determine the prevalence of cerebral saccular aneurysms in patients with carotid artery and/or vertebral artery (VA) fibromuscular dysplasia (FMD).

METHODS

A metaanalysis was performed using data from 17 previously reported series of patients with internal carotid artery (ICA) and/or VA FMD that included information on the prevalence of cerebral aneurysms. In addition, the authors retrospectively evaluated their own series of 117 patients with ICA and/or VA FMD to determine the prevalence of cerebral aneurysms. The metaanalysis of the 17 earlier series, which included 498 patients, showed a 7.6 +/- 2.5% prevalence of incidental, asymptomatic aneurysms in patients with ICA and/or VA FMD. In the authors' series of patients with FMD, 6.3 +/- 4.9% of patients harbored an incidental, asymptomatic aneurysm. When the authors' series was combined with those included in the metaanalysis, the prevalence was found to be 7.3 +/- 2.2%. The prevalence of aneurysms in the general population would have to be greater than 5.6% for there to be no statistically significant difference (chi-square test, p < 0.05) when compared with this 7.3% prevalence in patients with FMD.

CONCLUSIONS

The prevalence of intracranial aneurysms in patients with cervical ICA and/or VA FMD is approximately 7%, which is not nearly as high as the 21 to 51% prevalence that has been previously reported.

Bone morphogenetic protein gene therapy for the induction of spinal arthrodesis

Gene therapy has many potential applications in neurosurgery. One application involves bone morphogenetic protein-2 (BMP-2), a low-molecular-weight glycoprotein that induces bone formation in vivo. Numerous studies have demonstrated that the BMP-2 protein can enhance spinal fusion. This study was undertaken to determine whether direct injection of an adenoviral construct containing the BMP-2 gene can be used for spinal fusion. Twelve athymic nude rats were used in this study. Recombinant, replication-defective type-5 adenovirus with a universal promoter and BMP-2 gene (Ad-BMP-2) was used. A second adenovirus constructed with a universal promoter and ß-galactosidase (ß-gal) gene (Ad-ß-gal) was used as a control. Seven and one-half microliters of virus was injected percutaneously and paraspinally at the lumbosacral junction in three groups (four animals each): 1) Ad-BMP-2 bilaterally, 2) Ad-BMP-2 on the right, Ad-ß-gal on the left, and 3) Ad-ß-gal bilaterally. Computerized tomography (CT) scans of the lumbosacral spine were obtained at 3, 5, and 12 weeks. At 12 weeks, the animals were killed for histological inspection. Ectopic bone formation was seen both on three-dimensional CT reconstruction and histologically in all rats at sites treated with Ad-BMP-2. Histological analysis revealed bone at different stages of maturity adjacent to the spinous processes, laminae, and transverse processes. This study clearly demonstrated that it is possible to produce in vivo endochondral bone formation by using direct adenoviral construct injection into the paraspinal musculature, which suggests that gene therapy may be useful for spinal fusion in the future.

Guglielmi detachable coil embolization for unruptured aneurysms in nonsurgical candidates: a cost-effectiveness exploration

PURPOSE

We calculated the incremental cost-utility ratio for Guglielmi detachable coil (GDC) embolization versus no therapy for unruptured intracranial aneurysms considered inappropriate for surgical clipping procedures.

METHODS

Decision tree and Markov analyses that employ cohort simulation were applied to determine the incremental cost-utility ratio of GDC embolization versus no therapy for unruptured cerebral aneurysms. Clinical values required as input data were estimated from the literature for the following variables: relative frequencies of complete aneurysmal occlusion, partial aneurysmal occlusion, and attempted coiling (no coils detached); morbidity and mortality of GDC embolization; frequency, morbidity, and mortality of spontaneous aneurysmal rupture in untreated and GDC-embolized aneurysms; annual rate of recanalization of GDC-embolized aneurysms; quality of life when knowingly living with untreated or GDG-embolized aneurysms and of living with fixed neurologic deficit; costs of GDC embolization, spontaneous aneurysmal rupture, stroke, and rehabilitation; and discount rate. Cost-utility ratios below $50000 per quality-adjusted life year saved were considered acceptable. Sensitivity analyses were performed for all relevant input variables.

RESULTS

Baseline input values resulted in acceptable cost-utility ratios for GDC embolization of unruptured intracranial aneurysms. These ratios remained within acceptable limits across wide ranges of various input parameters. Cost-effectiveness was markedly affected by the natural course of unruptured, untreated aneurysms; rates of spontaneous rupture greater than 2% per year resulted in favorable cost-utility ratios that were relatively unaffected by variation in GDC efficacy, while rates of rupture less than 1% per year resulted in unfavorable ratios that were highly dependent on GDC efficacy. Many of the GDC efficacy indexes, such as rate of failed coiling, early recanalization, and progressive aneurysmal thrombosis, have mild effects on the cost-utility ratios. GDC complication rate as well as life expectancy had moderate effects on the analysis. The influence of late aneurysmal recanalization was mild unless high rates of rupture for partially coiled aneurysms were applied. Suboptimal clip placement resulting from the presence of GDC coils within a ruptured aneurysm had no demonstrable consequence on cost-utility ratios.

CONCLUSIONS

The single most influential variable determining the cost-effectiveness of GDC embolization in our analysis was the natural course of untreated aneurysms. Other important variables included GDC-related morbidity and life expectancy at the time of GDC embolization.

High-dose gadolinium-enhanced MRI for diagnosis of meningeal metastases

We compared high-dose (0.3 mmol/kg) and standard-dose (0.1 mmol/kg) gadolinium-enhanced MRI for diagnosis of meningeal metastases in 12 patients with suspected meningeal metastases. They were imaged with both standard-dose and high-dose gadolinium. All patients with abnormal meningeal enhancement underwent at least one lumber puncture for cerebrospinal fluid (CSF) cytology, while patients with normal meningeal enhancement were followed clinically. All patients with negative CSF cytology also were followed clinically. A single observer reviewed all the images, with specific attention to the enhancement pattern of the meninges. Abnormal leptomeningeal enhancement was present in three cases, and abnormal pachymeningeal enhancement in three other patients. All of these patients had abnormal CSF analyses. In two of the three cases of abnormal leptomeningeal enhancement the disease was more evident on high-dose than on standard-dose imaging; in one case the abnormal enhancement was visible only on high-dose imaging. In one of the three cases with abnormal pachymeningeal enhancement, the disease was evident prospectively only with high-dose imaging.

In vitro proliferation and adhesion of basic fibroblast growth factor-producing fibroblasts on platinum coils

PURPOSE

To evaluate the growth and adhesion characteristics in vitro of genetically modified, basic fibroblast growth factor-producing fibroblasts on platinum detachable coils.

MATERIALS AND METHODS

Coils of two sizes were coated with laminin, poly-L-lysine, fibronectin, and type I and type IV collagen and were cultured with basic fibroblast growth factor-secreting fibroblasts. Type I collagen strands were inserted in the lumen of some coils. Cellular proliferation and adherence during passage of coils through microcatheters were studied with both light and scanning electron microscopy. Growth factor concentration in the culture medium was measured.

RESULTS

Rapid cellular proliferation was noted on all coated coils except those coated with type IV collagen. Proliferation on uncoated coils was slightly slower than on most coated coils, although confluent cell layers were present on uncoated larger-diameter coils within 48 hours. Cells had a marked propensity to grow between the primary coil windings into the coil lumen, except in coils that contained collagen filaments. Passage through microcatheters caused widespread stripping of cells from the outer surface of coils, especially the uncoated samples. Viable cells remained in the coil lumen. Supernatant contained high concentrations of growth factor.

CONCLUSION

Platinum embolic coils are a promising mechanism of cell delivery for stimulation of scar formation or other desirable biologic effects.

Hemorrhagic complications in embolization of a meningioma: case report and review of the literature

We report a case of hemorrhage in a parasellar meningioma shortly after embolization of the dural cavernous carotid artery branches supplying the tumor. This represents the first report of hemorrhage within a meningioma resulting from embolization with small (50 to 150-microns) polyvinyl alcohol particles, as well as the first reported case of hemorrhage complicating meningioma embolization from internal rather than external carotid artery branch embolization. We also review previously reported cases of postembolization hemorrhage from meningiomas.

Percutaneous transvenous coil embolization of a type 4 sagittal sinus dural arteriovenous fistula: case report

OBJECTIVE AND IMPORTANCE

To present an alternative endovascular therapy for a Type 4 sagittal sinus dural arteriovenous fistula (DAVF).

CLINICAL PRESENTATION

A 74-year-old man presented with right facial paresthesias. Magnetic resonance imaging revealed an enlarged left parasagittal cortical vein adjacent to the superior sagittal sinus. Angiography demonstrated a Type 4 sagittal sinus DAVF.

INTERVENTION

The DAVF was cured using percutaneous transvenous coil embolization.

CONCLUSION

This case represents the first report in which a sagittal sinus DAVF was cured using a percutaneous transvenous endovascular approach.

Intracranial dissecting aneurysm causing subarachnoid hemorrhage: the role of computerized tomographic angiography and magnetic resonance angiography

BACKGROUND

With increasing frequency, dissecting aneurysms of the intracranial arteries are recognized as a possible cause of subarachnoid hemorrhage (SAH). In the presence of a dissecting aneurysm, angiographic changes may be subtle at presentation and correct diagnosis often requires serial angiograms. We report a patient with a dissecting aneurysm of the anterior cerebral artery (ACA) causing SAH, in whom less invasive diagnostic tools, such as high-resolution computerized tomographic angiography (CTA) and magnetic resonance angiography (MRA), were helpful in confirming the diagnosis and in following the evolution of the dissection.

CASE PRESENTATION

We present this 51-year old woman who experienced the sudden onset of severe headache without associated neurological deficits. Head CT showed SAH with blood in the interhemispheric fissure, suggesting a ruptured ACA aneurysm. Serial cerebral angiograms failed to demonstrate an aneurysmal sac, but showed evolving irregularities of the ACA consistent with a dissecting aneurysm. These findings were confirmed by CTA and MRA. The patient was treated conservatively and made an excellent recovery. A MRA obtained 2 months later showed slight improvement of the previously visualized ACA dilatation.

CONCLUSION

Serial angiograms are often required to confirm the diagnosis and to follow the evolution of an intracranial dissection. With recent advances in neuroradiological techniques, however, critical information can be obtained by less invasive imaging studies, such as CTA and MRA.

Patterns of hemorrhage with ruptured posterior inferior cerebellar artery aneurysms: CT findings in 44 cases

OBJECTIVE

We intended to characterize the CT patterns of hemorrhage associated with ruptured posterior inferior cerebellar artery (PICA) aneurysms.

MATERIALS AND METHODS

CT scans of 44 cases of angiographically confirmed ruptured saccular PICA aneurysms (4) aneurysms at the junction of the vertebral artery and the PICA and three distal PICA aneurysms) were retrospectively reviewed. All scans had been obtained within 2 days of the subarachnoid hemorrhage (SAH) (day 0 [less than 24 hr], 35 patients; day 1, eight patients; day 2, one patient). Presence or absence of hemorrhage in specific subarachnoid, intraventricular, and intraparenchymal locations was noted, as were the presence and degree of hydrocephalus.

RESULTS

Posterior fossa SAH was present in 95% of cases. Isolated posterior fossa SAH was present in 30% of cases, but in no case was isolated supratentorial SAH present. Supratentorial SAH was present in 70% of cases. SAH involving the sylvian fissure or the interhemispheric region was present in 25% and 23% of cases, respectively. SAH along the convexity was present in 2% of cases. Intraventricular hemorrhage (IVH) with or without associated SAH was seen in 95% of cases, whereas isolated IVH was seen in 5% of cases. Hydrocephalus was present in 95% of cases and was moderate to marked in 70%. Both IVH and hydrocephalus were present in 93% of cases.

CONCLUSION

Ruptured PICA aneurysms almost always coexist with hydrocephalus and IVH, as seen in 93% of cases, and almost never coexist with SAH along the convexity. The most common pattern of hemorrhage associated with such aneurysms includes IVH and posterior fossa hemorrhage. Extensive supratentorial SAH, in conjunction with posterior fossa SAH, is a common finding in patients with ruptured PICA aneurysms. SAH isolated to the posterior fossa is present in a sizeable minority of cases.

Cost-effectiveness of angiography performed during surgery for ruptured intracranial aneurysms

PURPOSE

To calculate the incremental cost-utility ratio for routine angiography performed during surgery for ruptured cerebral aneurysms.

METHODS

Decision-tree and Markov analyses based on a cohort simulation were used to determine the incremental cost-utility ratio of routine intraoperative angiography versus no angiography. Input data from the literature were estimated for the following variables: frequency of unexpected aneurysmal rests and branch artery occlusions; annual rate of rehemorrhage of partially clipped aneurysms; prevalence of clinically relevant infarction resulting from branch artery occlusion; efficacy of clip repositioning; morbidity associated with intraoperative angiography; morbidity and mortality associated with aneurysmal rehemorrhage; sensitivity of intraoperative angiography for aneurysmal rests; and costs of intraoperative angiography, added duration of surgery, ischemic cerebral infarction, aneurysmal rehemorrhage, and rehabilitation. Sensitivity analyses were performed for all relevant input variables. A societal perspective was used, and cost-utility ratios less than $50000/quality-adjusted life years (QALY) gained were considered acceptable.

RESULTS

Baseline input variables resulted in an acceptable cost-utility ratio for routine intraoperative angiography ($19000/QALY). The input variables with greatest influence on the cost-utility ratio were frequency of branch artery occlusions, angiographic morbidity, and cost of angiography. However, the cost-utility ratio remained acceptable even over wide ranges of these input variables. Frequency of unexpected partially clipped aneurysms, efficacy of clip repositioning, and costs of stroke, rehemorrhage, and rehabilitation had relatively little impact on the analysis.

CONCLUSION

Routine intraoperative angiography is cost-effective if performed in a manner consistent with low morbidity in a patient cohort harboring at least some unexpected branch artery occlusions that, if uncorrected, would result in clinically relevant cerebral infarctions.

Typical and atypical MR imaging features of intracranial epidermoid tumors

OBJECTIVE

We categorized the MR imaging characteristics of intracranial epidermoid tumors.

MATERIALS AND METHODS

MR images from 23 cases of intracranial epidermoid tumors were reviewed retrospectively. Signal intensities of tumor relative to surrounding structures were noted, as were the internal architecture of the tumors and the presence and degree of hydrocephalus.

RESULTS

Seventeen (74%) of 23 cases of intracranial epidermoid tumors were revealed as slightly hyperintense relative to CSF on T1-weighted MR images. Nineteen (95%) of 20 cases were hyperintense relative to CSF on proton density-weighted MR images. Fifteen (65%) of 23 cases were isointense to CSF on T2-weighted MR images, whereas the remaining eight cases (35%) were hyperintense to CSF on T2-weighted MR images. One (4%) of 23 cases showed signal intensity that was isointense to CSF on all pulse sequences. Fifteen (65%) of 23 cases showed heterogeneous signal characteristics on either T1-weighted or proton density-weighted MR images, or both. Eight (35%) of 23 cases showed a rim of hyperintensity on proton density-weighted MR images. Five (33%) of the 15 cases that received gadolinium showed rim enhancement. Five (22%) of 23 cases were multilocular, with different regions of tumors showing highly variable imaging characteristics. Two (9%) of 23 cases showed high signal intensity on T2-weighted MR images in the adjacent brain parenchyma. Two (9%) of 23 cases showed mild hydrocephalus. Six (43%) of 14 tumors that either originated in or secondarily involved the cerebellopontine angle also extended into the ipsilateral Meckel's cave.

CONCLUSION

On T1-, proton density-, and T2-weighted MR images intracranial epidermoid tumors usually showed heterogeneous signal intensity that was hyperintense to CSF. On all spin-echo pulse sequences epidermoid tumors with signal characteristics isointense to CSF were unusual. Hydrocephalus, even in the setting of marked displacement and compression of the brainstem, was not usually seen on MR imaging. Meckel's cave was often involved secondarily with epidermoid tumors that involved the cerebellopontine angle.

Routine angiography after surgery for ruptured intracranial aneurysms: a cost versus benefit analysis

PURPOSE

To assess the cost versus the benefit of routine cerebral angiography after surgery for ruptured aneurysms.

METHODS

Decision tree and Markov analyses that used cohort simulation were conducted to determine the incremental cost:benefit ratio of routine postsurgical angiography. Input data for unexpected partially clipped and unclipped cerebral aneurysms were estimated from the literature for the following variables: frequency; annual rate of subsequent hemorrhage; morbidity and mortality rates of subsequent hemorrhage; efficacy and morbidity and mortality rates of subsequent surgery; and costs of subsequent surgery, angiography, subsequent hemorrhage of aneurysm, and rehabilitation. RESULTS; Baseline input variables resulted in an acceptable cost:benefit ratio for routine postsurgical angiography. However, essentially all of the benefit was derived from intervening in cases of unexpected unclipped aneurysms rather than partially clipped aneurysms. Isolated instances of angiography and subsequent surgery for unexpected partially clipped aneurysms yielded unacceptable cost:benefit ratios. Surgical costs had minimal effect on the analysis.

CONCLUSIONS

When routine postsurgical angiography was performed primarily to diagnose and to subsequently operate on unexpected partially clipped aneurysms, the cost:benefit ratio was unacceptable. However, even low frequencies of unexpected unclipped aneurysms resulted in favorable cost:benefit ratios.

Thrombogenicity of hydrophilic and nonhydrophilic microcatheters and guiding catheters

PURPOSE

To assess in a swine model the in vivo thrombogenicity of various microcatheters and guiding catheters as a function of catheter material, catheter coating, and duration of implantation.

METHODS

Microcatheters (Tracker 18 and Fastracker 18, Target Therapeutics, Fremont, Calif; Magic 1.8, Balt, Montmorency, France; and Transit, Cordis Endovascular Systems, Miami Lakes, Fla) were placed through 6F guiding catheters (Fasguide, Target Therapeutics, and Envoy, Cordis Endovascular Systems) into the common carotid arteries of swine for 30 minutes (short term), 90 minutes (medium term), and 35 days (long term). Guiding catheters were implanted for 5 hours. At the end of the implantation periods the catheters were retracted and fixed for scanning electron microscopy.

RESULTS

The surface of the Fastracker microcatheter was devoid of debris after both short- and medium-term implantation. The Tracker microcatheter had minimal accumulation of cellular elements whereas the Transit microcatheter showed moderate accumulation of nondeformed red blood cells. Neither the Tracker nor the Transit microcatheter showed evidence of increasing debris accumulation after medium-term implantation as compared with short-term implantation. The Magic microcatheter was coated with gross thrombus after both short- and medium-term implantation. The Fasguide guiding catheter was nearly devoid of debris, while the Envoy guiding catheter had moderate thrombus formation. Long-term implantation of the Fastracker microcatheter was well tolerated whereas that of the Transit catheter resulted in vessel occlusion.

CONCLUSIONS

Hydrophilic microcatheters and guiding catheters are less thrombogenic than their nonhydrophilic counterparts, but not all hydrophilic coatings are equally hypothrombogenic. Degree of thrombogenicity depends on catheter material rather than surface morphology. Medium-term implantation did not yield increasing thrombus formation relative to short-term implantation.

Partial pediculectomy in the treatment of lumbar spinal stenosis: technical note

OBJECTIVE

We note an additional pathological condition associated with lumbar spinal stenosis that may be responsible for significant postoperative pain. Recognizing that nerve roots are stretched around hypertrophic pedicles in some cases of spinal stenosis, we have altered our surgical management of these cases to address what may be a previously unrecognized but significant anatomic pathological finding.

SURGICAL TECHNIQUE

After ipsilateral posterior bony decompression of the spinal canal, the nerve root is examined as it courses around the pedicle. If the root appears stretched, the medial part of the pedicle is removed using first a diamond bit and then a curet. The nerve root is retracted and protected during this procedure.

RESULTS

Inspection of the root after partial pediculectomy frequently reveals lateral movement of the root into space previously occupied by the pedicle. Anatomically, the nerve is better decompressed and free of obstruction. This technique adds little time to the overall duration of the operation.

CONCLUSION

Anatomic evidence obtained through intraoperative examination and preoperative imaging techniques indicates that partial pediculectomy may play a role in the treatment of some cases of lumbar stenosis.

The normal anterior commissure of the glottis

OBJECTIVE

We characterized the normal width of the anterior commissure of the glottis by measuring its dimensions on CT scans obtained in patients who had no laryngeal disorders.

SUBJECTS AND METHODS

CT scans of patients referred for cervical CT myelography were prospectively reviewed by a single board-certified radiologist. Axial images through the anterior commissure (localized by vocal process of the arytenoid cartilage, the vocal muscle, or both) were magnified on the viewing console of the CT scanner. Window and level were chosen to simulate our routine settings for CT scans of the neck. Anteroposterior width of the anterior commissure was measured using an electronic ruler with 1-mm marks.

RESULTS

Sixty-five patients were prospectively evaluated. Nine patients were excluded because of substantial motion artifact, and another 18 were excluded because CT images did not include the entire larynx. Thus, the final study group included 38 patients. The average width of the anterior commissure was 1.02 +/- 0.56 mm. The width was less than or equal to 1.1 mm in 22 (58%) of 38 patients. The width was less than or equal to 1.7 mm in 35 (92%) of 38 patients. Forty-two percent (16 of 38 patients) had anterior commissures wider than 1.0 mm. The maximum width of 2.2 mm was seen in only one patient.

CONCLUSION

The mean width of the anterior commissure was approximately 1.0 mm. However, 42% of patients had anterior commissures wider than 1.0 mm. In our series, using an upper limit of 1.6 mm as a normal measurement for the anterior commissure would have included 92% of patients, and an upper limit of 2.1 mm would have encompassed the mean plus two SDs.

Percutaneous transvenous coil embolization of a Djindjian type 4 tentorial dural arteriovenous malformation

We report a 60-year-old man who had a progressive neurologic deficit resulting from a Djindjian type 4 tentorial dural arteriovenous malformation (DAVM). The DAVM was repaired via percutaneous transvenous coil embolization.

Accuracy and precision of CT angiography in a model of carotid artery bifurcation stenosis

PURPOSE

To determine optimal acquisition parameters and measurement techniques for CT angiography of the carotid bifurcation.

METHODS

Anatomic phantoms were created in which the diameter of the carotid artery stenoses ranged from 15% to 95%. Initially, we compared the accuracy of stenosis determination obtained by using various values of section collimation and table pitch. Subsequently, applying the combination of collimation and pitch that yielded the greatest longitudinal coverage without degradation in accuracy, we compared the accuracy of measurements performed with various display algorithms, including axial, magnified axial, maximum intensity projection (MIP), and shaded surface display (SSD) images. Last, we determined the effect on accuracy of varying both window and level settings. The standard of reference for all measurements was considered to be caliper measurements made of the models at the time of their construction.

RESULTS

CT angiography was highly accurate for determining the percentage of stenosis; the average difference between CT angiographic measurements and the standard of reference was less than 1% for all parameter combinations and measurement techniques. Precision varied among the measurement techniques. Magnified axial images provided more precise measurements than either the MIP or SSD images. Although there was a trend toward improved precision with the use of magnified versus unmagnified axial images and MIP versus SSD images, neither of these comparisons reached statistical significance. Systematic error was produced by changing the level setting from that halfway between the luminal density and vessel wall density. Random error was introduced by using window settings greater than zero.

CONCLUSION

CT angiography was highly accurate and precise for determining percentage of stenosis. The highest precision was attained by using magnified axial images with the level halfway between luminal density and vessel wall density and with the window set to zero.

Utilization of type I collagen gel, demineralized bone matrix, and bone morphogenetic protein-2 to enhance autologous bone lumbar spinal fusion

Autologous bone grafts are currently considered "gold standard" material for achieving long-term spinal arthrodesis. The present study was performed to determine whether demineralized bone matrix (DBM), type I collagen gels, or bone morphogenetic protein-2 (BMP-2) can improve autologous bone spinal fusions. Using a unilateral decompression-contralateral fusion technique in dogs, each of these materials was added to an autologous bone graft. Volumetric analysis, histological analysis, and biomechanical testing were performed to assess the effectiveness of each material. The DBM had an inhibitory effect on solid bone fusion of the spine, whereas the type I collagen gels improved the bony interface between the graft and the host spine. The BMP-2 strongly enhanced the amount of bone deposition at the fusion site and increased the number of intervertebral levels that were solidly fused. This study strongly supports the use of BMP-2 as an additive to autologous bone grafts in spine stabilization.

Percutaneous polymethylmethacrylate vertebroplasty in the treatment of osteoporotic vertebral body compression fractures: technical aspects

PURPOSE

To describe a technique for percutaneous vertebroplasty of osteoporotic vertebral body compression fractures and to report early results of its use.

METHODS

The technique was used over a 3-year period in 29 patients with 47 painful vertebral fractures. The technique involves percutaneous puncture of the involved vertebra(e) via a transpedicular approach followed by injection of polymethylmethacrylate (PMMA) into the vertebral body.

RESULTS

The procedure was technically successful in all patients, with an average injection amount of 7.1 mL PMMA per vertebral body. Two patients sustained single, nondisplaced rib fractures during the procedure; otherwise, no clinically significant complications were noted. Twenty-six patients (90%) reported significant pain relief immediately after treatment.

CONCLUSION

Vertebroplasty is a valuable tool in the treatment of painful osteoporotic vertebral fractures, providing acute pain relief and early mobilization in appropriate patients.

Ruptured vertebrobasilar aneurysms: frequency of the nonaneurysmal perimesencephalic pattern of hemorrhage on CT scans

PURPOSE

To determine the frequency of the computed tomographic (CT) pattern of nonaneurysmal perimesencephalic subarachnoid hemorrhage in the setting of ruptured posterior fossa aneurysms.

MATERIALS AND METHODS

Four neuroradiologists independently and retrospectively reviewed cranial CT scans of 169 patients with ruptured vertebrobasilar aneurysms (44 cases of posteroinferior cerebellar artery aneurysm, 20 cases of superior cerebellar artery aneurysm, and 105 cases of basilar-tip aneurysm).

RESULTS

The mean frequency of nonaneurysmal perimesencephalic pattern of subarachnoid hemorrhage in ruptured vertebrobasilar aneurysms was 7.1% (48 of 676 readings) among the four readers. The mean frequency of aneurysms with the pattern of hemorrhage for each location was as follows: basilar tip, 9.8% (41 of 420 readings); superior cerebellar artery, 5.0% (four of 80 readings); and posteroinferior cerebellar artery, 0%. In 75% (six of eight) of the cases in which the CT pattern of hemorrhage was deemed compatible by all readers with nonaneurysmal hemorrhage, the clinical presentation was mild.

CONCLUSION

Because ruptured posterior fossa aneurysms manifest with the nonaneurysmal pattern of hemorrhage in approximately 10% of cases, a high degree of suspicion should be maintained even if the pattern of subarachnoid hemorrhage suggests a nonaneurysmal origin and clinical symptoms are mild.