Long-term histopathologic findings in two cerebral aneurysms embolized with Guglielmi detachable coils.

We present gross pathologic autopsy findings of a patient who was treated for two aneurysms with Guglielmi detachable coils (GDCs), and who died 33 months after the procedure. Histologic findings are also presented. In both aneurysms, the coils were firmly attached to the aneurysmal wall, making it impossible to remove them from the sac. The ostium of one aneurysm was covered by collagenous tissue and a single layer of endothelium.     

Long-term histopathologic changes in canine aneurysms embolized with Guglielmi detachable coils.

PURPOSETo evaluate the long-term histologic changes, including those in the ultrastructure of the neoendothelium, occurring in experimental canine aneurysms obliterated with Guglielmi detachable coils.METHODSTen experimental aneurysms were surgically created in mongrel dogs using side-to-side jugular carotid fistulas that were subsequently ligated to form blind pouch venous aneurysms dependent on the carotid circulation. The aneurysms were obliterated with Guglielmi detachable coils, and the animals were kept in observation. Six months after the endovascular obliteration of the aneurysms, repeat carotid arteriography was performed to assess for potential recanalization of the aneurysms. The animals were then killed and submitted for autopsy. The carotid artery and the embolized aneurysm were resected and studied with light and electron microscopy.RESULTSBoth completely obliterated and recanalized aneurysms were excluded from the parent circulation by an endothelialized layer of connective tissue. The fundus of the aneurysm was completely obliterated by heavy reactive fibrous tissue surrounding the coils with very minimal, if any, inflammatory reaction. The neointima is composed of three well-identifiable layers, the most superficial of which is formed of new endothelial cells positioned next to each other in a cobblestone fashion over a basal membrane.CONCLUSIONIn the absence of histologic data in human aneurysms obliterated with Guglielmi detachable coils, several observations made in our experimental study help in the understanding of the long-term results expected from this endovascular technique.     

Angiographic and histologic analysis of experimental aneurysms embolized with platinum coils, Matrix, and HydroCoil

BACKGROUND AND PURPOSE: A report directly comparing platinum coils, Matrix coils, and HydroCoils in a single animal model does not currently exist. We evaluated and compared the performance of these three products in the embolization of experimental aneurysms. METHODS: Thirty-three elastase-induced saccular aneurysms were created in rabbits. Aneurysms were embolized with Matrix coils (n = 15), HydroCoils (n = 9), or platinum coils (n = 9). The groups were compared with respect to the following parameters: aneurysm size, procedure duration, number and total length of devices deposited, angiographic occlusion score, and volumetric occlusion percentage. Follow-up angiographic and histologic features at 2, 6, and 10 weeks after embolization were analyzed. Groups were compared by using analysis of variance and chi2 tests. RESULTS: No significant differences were found among groups regarding aneurysm size, total device length, initial angiographic occlusion score, or procedure time. The mean number of devices for Matrix subjects was less than that for platinum coils (P = .02) and HydroCoil (P = .03). Volumetric occlusion for HydroCoil (76%) was significantly greater (P < .0001) than both platinum coils (31%) and Matrix (23%). Angiographic durability was significantly increased in the HydroCoil group compared with Matrix (P = .03). Coil compaction was found more frequently in the Matrix group (five cases, 33%) than the HydroCoil (no cases, 0%), or platinum coil groups (two cases, 22%). The Matrix group showed greater tissue reaction compared with platinum coils (P < .05). CONCLUSION: In the rabbit model, the use of HydroCoils results in improved long-term occlusion rates compared with Matrix and platinum coils. The Matrix group showed an increase in inflammation and coil compaction compared with HydroCoils and platinum coils.     

MR angiographic evaluation is limited in intracranial aneurysms embolized with Nexus coils

Introduction Nexus coils are a type of bioactive coil used to embolize intracranial aneurysms. The purpose of this study was to test the feasibility of the noninvasive follow-up of aneurysms treated with Nexus coils by means of magnetic resonance angiography (MRA). Methods Three-dimensional (3D) time-of-flight (TOF) MRA images of patients treated with Nexus coils (the Nexus coil group) or bare platinum coils (the control group) were compared for the severity and frequency of artifacts. The reviewers were unaware of the coil types used. In the Nexus coil group, 17 MRA examinations were performed in 14 patients harboring 15 aneurysms treated with Nexus coils using 3-T (n = 11) and 1.5-T (n = 6) MR units. The findings of these examinations were compared to those of 28 MRA studies conducted on 24 control patients (bare platinum coils). Conventional angiograms, maximum intensity projections, and source data of 3D-TOF MRA were reviewed in terms of residual flow within aneurysms and parent arterial patencies. The qualities of the MRA images were rated from grade 0 (no significant signal loss) to grade 2 (complete segmental signal loss of the parent artery). The normalized ratio, defined as the diameter of signal loss on MRA axial source images (in mm) divided by that of coil mass on plain radiographs (in mm), was calculated to compare the sizes of coil-related artifacts in the two groups. Results The quality of the MRA image for the Nexus coil group was significantly poorer than that for the control group (p < 0.0001) due to signal loss caused by the presence of artifacts in the former. In particular, the interpretation of aneurysmal status was impossible in all cases of coiled aneurysms due to segmental signal loss. The sizes of the MRA artifacts were also significantly larger in the Nexus coil group (normalized ratio 1.61 ± 0.22 vs. 1.15 ± 0.20; p < 0.0001). Conclusion Follow-up evaluations by 3D-TOF MRA of aneurysms treated with Nexus coils are severely limited.     

Histopathologic findings in human cerebral aneurysms embolized with platinum coils: report of two cases and review of the literature

This report describes 2-week and 20-month histopathologic findings in small aneurysms embolized with platinum coils. Electron microscopy showed the presence of endothelial cells encroaching on the platinum coils at the orifice of the aneurysm in both cases. We confirm that endothelial growth can be induced as early as 2 weeks after embolization of small human aneurysms with platinum coils, similar to previous observations in animal models and human cases.     

Treatment of carotid artery aneurysms with platinum coils: an experimental study in dogs

The objectives of this study were to investigate the consistency, patency, and natural history of a vein graft canine aneurysm model and to determine the effectiveness of various coil designs on inducing aneurysm thrombosis. Twenty-one sacculuslike aneurysms were created in mongrel dogs by anastomosing a vein pouch to the common carotid artery. The model produced wide-neck aneurysms with 100% patency. The canine vein graft aneurysm provided an excellent model for the evaluation of endovascular devices. Three types of specially designed platinum coils were placed in the aneurysms: those with simple curves, those with complex curves, and those with flower petal curves and silk fibers. These coils were placed by the endovascular route by means of microcatheters. Flower petal coils with silk fibers were effective in producing thrombosis of the aneurysms, suggesting that coils of the appropriate design may be useful in the endovascular treatment of aneurysms. The other coil designs evaluated, those with simple and complex curves without silk fibers, demonstrated insufficient thrombogenicity and spatial stability.     

Atherosclerotic plaque at the carotid bifurcation: CT angiographic appearance with histopathologic correlation.

BACKGROUND AND PURPOSE: The likelihood that carotid plaque will give rise to cerebral ischemia probably relates to the degree of arterial stenosis and to plaque morphology. The aim of this study was to assess whether features seen at CT angiography might be used to predict carotid plaque stability by comparing CT angiograms with histopathologic examinations of the carotid artery bifurcation. METHODS: Nine patients with symptomatic severe carotid stenosis at intraarterial angiography had CT angiography of the carotid bifurcation before carotid endarterectomy. After endarterectomy, multiple sections of the specimens through the carotid bifurcation were examined histologically. Plaque characteristics recorded included the proportion of necrotic/lipid core, presence of hemorrhage, extent of fibrosis, ulceration, calcification, inflammatory cell infiltrate, and fibrous cap thickness. Corresponding CT angiograms were assessed for plaque size, distribution, and radiodensity as well as presence of calcific density and ulceration. Histologic findings and CT angiograms were compared. RESULTS: Plaque with a large necrotic/lipid core, which was often hemorrhagic, was found in 16 of 23 sections, and in 15 of these this histologic appearance corresponded with patchy or homogeneous low density on CT angiograms. Six of seven predominantly fibrous plaques were of soft-tissue density on CT angiograms. High density consistent with calcification was seen more frequently on CT angiograms than it was detected histologically, but CT angiography depicted plaque ulceration poorly (four ulcers at histology; two false-positive and two false-negative findings at CT angiography). CONCLUSION: CT angiography is a promising method for assessing the lumen and wall of the carotid artery. The apparent correlation between histologic appearance and plaque density on CT angiograms has important implications for the prediction of plaque stability, even though ulceration is shown inconsistently.     

Bone formation in elastase-induced rabbit aneurysms embolized with platinum coils: report of 2 cases

Histologic findings in 71 elastase-induced rabbit aneurysms embolized with platinum coils were retrospectively reviewed. Mature bone formation was found in 2 aneurysms, one with coils implanted for 3 months and the other with coils implanted for 1 year. We present the histologic findings and offer potential explanations for these observations. These findings may be relevant in understanding mechanisms of aneurysm healing after coil embolization.     

Long-term angiographic follow-up of 169 intracranial berry aneurysms occluded with detachable coils.

PURPOSE: To evaluate the stability of aneurysm occlusion at follow-up angiography after endovascular treatment (EVT) with detachable coils in intracranial berry aneurysms. MATERIALS AND METHODS: A total of 203 berry aneurysms (< 1.5 cm) were treated with EVT. Follow-up angiography at least 3 months later was performed in 169 cases. RESULTS: Complete occlusion of the aneurysm sac and neck was achieved in 148 aneurysms, subtotal occlusion in 18, and incomplete occlusion in three. Recurrence occurred between 3 and 40 months in 20 (14%) of the 148 totally occluded aneurysms. A second treatment was performed in five cases, was scheduled in one, and failed in one. The small neck remnant increased in size but did not require any retreatment in three cases, and the size of the neck remnant remained stable in 10 cases. Remnant regrowth occurred in six of the 18 subtotally occluded aneurysms. A second treatment was performed in three. Of the 169 cases, last follow-up angiography showed total occlusion in 133 cases, subtotal in 30, and incomplete in six. No rebleeding occurred. CONCLUSION: A very small recurrence may be observed at the level of the neck of the aneurysm at long-term follow-up angiography despite achieving total occlusion initially with detachable coils.     

Histopathologic and immunohistochemical comparison of human, rabbit, and swine aneurysms embolized with platinum coils

BACKGROUND AND PURPOSE: The purpose of this study was to clarify the cellular mechanisms of aneurysmal healing by comparing histologic and immunohistochemical findings in experimental rabbit and swine aneurysms to a human aneurysm embolized with platinum coils. METHODS: Swine sidewall aneurysms (n = 5, harvested at 12 weeks) and elastase-induced rabbit aneurysms (n = 6, harvested at 24 weeks) were created and embolized. A single human aneurysm, embolized 6 years before death, was harvested following autopsy. All specimens were processed by using a modified paraffin embedding technique. Tissue was sectioned and stained with hematoxylin and eosin and Masson trichrome. Immunohistochemistry and immunofluorescence were performed with multiple antibodies, including alpha smooth muscle actin, myosin heavy chain, desmin, vimentin, and CD31. RESULTS: The human aneurysm's dome was filled with loose, hypocellular, amorphous tissue. The aneurysm's neck was completely covered with a thin layer of hypocellular tissue. Collagen and myofibroblasts were sparse in both the dome and neck. Rabbit aneurysms' domes were also filled with a loose, hypocellular tissue, amorphous matrix. In 5 of 6 aneurysms, a thin layer of hypocellular tissue ran along the neck. Collagen and myofibroblasts were sparse in the dome. Swine aneurysms were filled with densely infiltrated tissue, including chronic inflammatory tissue and extensive, attenuated collagen fiber bundles associated with myofibroblasts. Thick layers of myofibroblasts entirely bridged the necks. CONCLUSIONS: Absence of collagen deposition and scant myofibroblastic reaction to platinum coil embolization are seen in the rabbit model but not in swine aneurysms. The elastase-induced aneurysm model in rabbits is more suitable than sidewall swine aneurysms for testing of modified devices aimed at improving intra-aneurysmal fibrosis.     

The nature of thrombosis induced by platinum and tungsten coils in saccular aneurysms.

PURPOSETo compare the efficacy and biocompatability of electrolytic and mechanically detachable embolization coils of two metal types.METHODSExperimental saccular aneurysms in pigs were used to assess embolization induced by platinum or tungsten coils. Longitudinal angiographic and histologic studies were performed on treated and untreated (control) aneurysms to compare thrombosis and cellular responses after embolization with electrolytically detachable platinum coils and with mechanically detached tungsten coils.RESULTSFewer tungsten than platinum coils were needed to induce thrombosis. The inflammatory response within the aneurysmal lumen was more florid in embolized aneurysms than in control aneurysms. No difference was found in the timing or extent of accumulation of eosinophils, lymphocytes, or polymorphs between the two coils used. Giant cell responses were more marked in treated aneurysms; tungsten coils more than platinum coils. The amount of collagen and fibrosis present increased over the study period and was similar in treated and control aneurysms.CONCLUSIONThe coil type influenced the initial cellular response but had little effect on the rate or degree to which blood clot within the aneurysm was replaced by fibrous tissue.     

支架辅助微弹簧圈栓塞颅内动脉瘤的应用价值

 目的 探讨应用颅内专用支架结合微弹簧圈栓塞治疗颅内动脉技术的临床应用价值。方法44例中,男性20 例,女性24例,通过微导管放置颅内专用支架,支架覆盖动脉瘤瘤颈,同时以另一微导管进入动脉瘤腔微弹簧圈栓塞动脉瘤。结果全部病例采用颅内专用 支架辅助微弹簧圈栓塞,其中38 例致密栓塞,6 例部分栓塞。术中、术后未发生颅内出血及支架内血栓形成,患者均恢复良好。36例术后3～6个月脑血管造影随访：其中35 例致密栓塞的动脉瘤均未显影,载瘤动脉通畅;1例动脉瘤颈有残留,未见动脉瘤复发;6例患者术后3个月内,未随访;2例失访。结论支架结合弹簧圈栓塞颅内动脉瘤有较好的疗效。     

Internal carotid bifurcation aneurysms: frequency, angiographic anatomy and results of coiling in 50 aneurysms

INTRODUCTION: Internal carotid artery (ICA) bifurcation aneurysms are uncommon. Little is known about incidence, anatomical characteristics and results of endovascular treatment. We report our experience with endovascular treatment of 50 ICA bifurcation aneurysms in 46 patients. METHODS: There were 13 men (28%) and 33 women (72%) with a mean age of 49.3 years (range 23-76 years). Of 50 aneurysms, 26 (52%) were ruptured and 24 (48%) were unruptured. Of the 46 patients, 23 (50%) had one to five additional aneurysms. RESULTS: The frequency of ICA bifurcation aneurysms was 2.4% (53 of 2,249, 95% CI 1.8-3.1%). Their mean size was 9.6 mm (median 6 mm, range 2-55 mm). Aneurysm neck was symmetrically on A1 and M1 in 30 aneurysms (60%), dominant on A1 in 14 (28%), on M1 in 2 (4%) and on the ICA in 4 (8%). Aneurysm fundus projection was superior in 28 aneurysms (56%), posterior in 9 (18%), anterior in 10 (20%) and lateral in 3 (6%). Four aneurysms were coiled with balloon assistance. Procedural morbidity and mortality of coiling was 2% each. During follow-up, 7 of 50 aneurysms (all 10 mm or larger) were additionally treated (retreatment rate 14%). CONCLUSION: ICA bifurcation aneurysms are rare with a frequency of 2.4% of treated aneurysms in our institution. They are often associated with additional aneurysms. Most aneurysm necks are located symmetrically on A1 and M1 and fundus projection is mostly superior. Coiling is safe and effective for the management of these aneurysms. The aneurysms that needed retreatment were >/=10 mm.     

MRA of intracranial aneurysms embolized with platinum coils: a vascular phantom study at 1.5T and 3T

PURPOSE: To analyze the influence of matrix and echo time (TE) of three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) on the depiction of residual flow in aneurysms embolized with platinum coils at 1.5T and 3T. MATERIALS AND METHODS: A simulated intracranial aneurysm of the vascular phantom was loosely packed to maintain the patency of some residual aneurysmal lumen with platinum coils and connected to an electromagnetic flow pump with pulsatile flow. MRAs were obtained altering the matrix and TE of 3D TOF sequences at 1.5T and 3T. RESULTS: The increased spatial resolution and the shorter TE offered better image quality at 3T. For the depiction of an aneurysm remnant, the high-spatial-resolution 3T MRA (matrix size of 384 x 224 and 512 x 256) with a short TE of < or =3.3 msec were superior to the 1.5T MRA obtained with any sequences. CONCLUSION: 3T MRA is superior to 1.5T MRA for the assessment of aneurysms embolized with platinum coils; the combination of the 512 x 256 matrix and short TE (3.3 msec or less) seems feasible at 3T.     

Intracranial aneurysms: treatment with bare platinum coils--aneurysm packing, complex coils, and angiographic recurrence

PURPOSE: To retrospectively assess, with three-dimensional rotational angiography, the relationship between packing, complex coils, and angiographic recurrence of aneurysms treated with coils. MATERIALS AND METHODS: Informed consent was waived by the institutional review board that approved the study. Results at follow-up angiography of 255 aneurysms in 223 patients (161 female and 62 male patients; mean age, 48 years) were dichotomized into presence or absence of recurrence. The degree of packing of aneurysms treated with complex coils alone, with complex and helical coils, and with helical coils only was compared for significant differences. With generalized estimating equations analysis, relative risk (RR) for recurrence was calculated for mode of manifestation, duration of follow-up, aneurysm volume, packing, initial angiographic result, percentage of complex coils, aneurysm location, and multiplicity of aneurysms. RESULTS: Follow-up angiography revealed recurrence in 28.6% of aneurysms at a mean follow-up of 12 months; 5.5% were amenable to re-treatment. Aneurysms treated with complex and those treated with helical coils only had a mean packing of 27% and 26%, respectively. There was no significant difference between packing of aneurysms treated with complex and those treated with helical coils (P = .538). Recurring and stable aneurysms both had a mean packing of 27%. Generalized estimating equations analysis showed significant differences between duration of follow-up and recurrence (P = .001, RR = 3.39), between aneurysm volume and recurrence (P < .001, RR = 6.15), and between hemorrhagic manifestation and recurrence (P = .002, RR = 3.17). There was no significant difference between packing and recurrence, between initial angiographic result and recurrence, between percentage of complex coils and recurrence, between aneurysm location and recurrence, or between multiplicity of aneurysms and recurrence. CONCLUSION: More angiographic recurrences are detected over time. Complex coils do not augment aneurysm packing. Packing is not related to protection against recurrence.     

A longitudinal immunohistochemical study of the healing of experimental aneurysms after embolization with platinum coils

BACKGROUND AND PURPOSE: The purpose of this study was to probe the cellular mechanism of healing in aneurysms after platinum coil embolization, by using multiple special stains and immunolabels. METHODS: Elastase-induced aneurysms were created and embolized in 28 rabbits. Aneurysms were excised between 2 and 24 weeks after embolization. Specimens were embedded in paraffin, sectioned, and stained with hematoxylin-eosin, Masson trichrome, and multiple immunostains. RESULTS: At 2 weeks, peripheral sparse spindle-nucleated cells were positive for alpha-smooth muscle actin (SMA), myosin, and vimentin, indicating myofibroblastic differentiation. At 4 weeks, all spindle-nucleated cells in the aneurysm were positive for SMA, myosin, desmin, and vimentin. Ten weeks after embolization, positive immunohistochemical staining in the cells populating the aneurysm significantly decreased. Mean positive SMA cells, per high-powered field were 5 +/- 3, 45 +/- 9, 10 +/- 5, 0 +/- 0, and 0 +/- 0 at 2, 4, 10, 16, and 24 weeks, respectively. Findings of a Kruskal-Wallis test showed these data to be significantly different (P =.0001). Post hoc tests revealed significantly greater amounts of SMA-positive staining in the cells at 4 weeks compared with those at 2, 10, 16, and 24 weeks (P < .05). In addition, the 10-week group had significantly more positive cells than the 16- and 24-week groups (P < .05). There was a 78% decrease in apoptotic cells between 4 (37 +/- 11) and 10 weeks (8 +/- 4) after implantation. Apoptotic cells were completely absent beyond 10 weeks. CONCLUSION: Aneurysm healing, in response to platinum coil embolization, appeared to progress through the stages of thrombus formation, granulated tissue organization, and loose connective tissue formation. Myofibroblasts, the key cellular component involved in healing, appeared within the aneurysm early. They progressively reduced in number with time and finally disappeared through the mechanism of apoptosis.