Embolization of cerebral arteriovenous malformations with cellulose acetate polymer: a clinical, radiological, and histological study.

OBJECTIVE: A cellulose acetate polymer (CAP) solution was hypothesized to be useful for the embolization of arteriovenous malformations (AVMs). To investigate this possibility, we analyzed the clinical, radiological, and histological results of patients with AVMs embolized by using a CAP solution. METHODS: We reviewed the cases of 11 patients with AVMs treated by embolization before surgical resection. We used two types of CAP solutions, CAP-M and CAP-L, which are mixtures of 250 mg of solid CAP and 1800 or 2250 mg of bismuth trioxide dissolved in 5.5 or 7.0 ml of dimethyl sulfoxide, respectively. After the embolization procedure, percent reduction of the nidus volume was measured, and thereafter, the clinical course and computed tomographic scans and/or magnetic resonance imaging scans were evaluated. All patients underwent surgical resection 1 to 51 days after embolization. Resected specimens were stained for light microscopic examination. RESULTS: Thirty-nine feeding vessels were embolized. The reduction rate of the nidus volume ranged from 20% to nearly 100%. Transient and persistent ischemic deficits occurred in three patients and one patient, respectively, and there were no hemorrhagic complications. All AVMs but one were completely resected by surgery. The embolized AVMs were soft enough to be easily cut and retracted. The histological examinations disclosed no or mild inflammatory reactions within 2 weeks after embolization. The internal elastic lamina was preserved in every case. Recanalization through the cast of the CAP mass was not observed until 51 days after embolization. CONCLUSION: CAP solution is a safe and useful embolic agent for AVMs.

Cellulose acetate polymer thrombosis for the emergency treatment of aneurysms: angiographic findings, clinical experience, and histopathological study.

Cellulose acetate polymer solution is a liquid thrombotic material that hardens into the shape of an aneurysm into which it is injected. Therapy using this solution is a rapid technique that helps prevent the rupture of aneurysms, especially those that extravasate contrast material during angiography in the acute stage of subarachnoid hemorrhage. Using this polymer solution and an endovascular technique, we treated two patients who had aneurysms of the basilar and anterior communicating arteries with extravasation of contrast material during angiography a few hours after the initial subarachnoid hemorrhage. In one patient with an aneurysm of the anterior communicating artery, the aneurysm's wall was perforated with the catheter during neurointerventional procedures. In both patients, postoperative angiograms demonstrated obliteration of the aneurysmal dome, including the site of extravasation or perforation. The parent artery and surrounding perforating branches were preserved. Although we do not advocate aggressive therapy for patients who bleed during angiography, we pursued this therapy in these two patients because of the opportunity to introduce cellulose acetate polymer in an attempt to preserve the patients' lives. Unfortunately, both patients died. Histopathological studies performed at the time of autopsy demonstrated that the luminal surface of cellulose acetate polymer was covered with thrombus by 6 days after cellulose acetate polymer thrombosis. By 10 days, the thrombus had a prominent fibrin network, a concentrated plasma component, and few fibrocytes adhering to its luminal surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial thrombosis of canine carotid bifurcation aneurysms with cellulose acetate polymer.

OBJECTIVE: To investigate the usefulness of a cellulose acetate polymer (CAP) solution for partial thrombosis of aneurysms. METHODS: We created 14 canine cervical carotid bifurcation aneurysms, 11 of which were subsequently thrombosed partially with CAP solution. We then conducted angiographic and histological investigations. RESULTS: Nine aneurysms were thrombosed 50 to 70% by volume, although a significant crescent crevice between the aneurysmal sac and the CAP mass was left in four of the aneurysms. In the remaining two aneurysms in which a crescent crevice had been seen in the initial stage of CAP injection, 80% and more than 95% thrombosis were needed to occlude the crevice, respectively. Follow-up angiograms of the seven aneurysms with no crescent crevice revealed no shifts of position of the CAP mass toward the bottom of the aneurysm sac, but slight ballooning of the remnants was observed in two of them. The angiograms of the other four aneurysms with significant crescent crevices demonstrated rupture with a massive hematoma in one and shifts of the CAP mass with marked enlargement of remnants in three. Histologically, the seven aneurysms with no enlarged remnants had newly developed membranes consisting of endothelium, infiltrated spindle-shaped cells, collagen, and elastic fibers. In contrast, in the three markedly enlarged aneurysms, there were only recent clots between the CAP mass and the aneurysm lumen and no development of endothelium. CONCLUSION: Partial thrombosis with CAP solution is useful to keep aneurysms in a stable configuration, unless a crescent crevice has been left.

Prophylactic thrombosis to prevent new bleeding and to delay aneurysm surgery.

Six aneurysms in five patients with acute aneurysmal subarachnoid hemorrhages were treated with direct thrombosis using cellulose acetate polymer within 4 hours of rupture. The aneurysms involved the internal carotid and posterior communicating arteries (two patients), the anterior choroidal artery (one patient), the bifurcation of the basilar artery (one patient), and the middle cerebral artery (two patients). Four patients underwent aggressive volume expansion after direct thrombosis with cellulose acetate polymer. The aneurysms remained thrombosed until operations on the necks were performed 2 to 7 weeks after the subarachnoid hemorrhages. Three patients were given intrathecal tissue plasminogen activator. One patient, who remained at neurological Grade V, was not treated surgically and died from cardiac failure. Five aneurysms in the remaining four patients were successfully clipped. These preliminary data suggest that immediate aneurysmal thrombosis, then aggressive preoperative prophylactic volume expansion and/or administration of intrathecal tissue plasminogen activator, can help prevent new bleeding and reduce delayed cerebral ischemia in patients after aneurysmal subarachnoid hemorrhages.

Direct thrombosis of aneurysms with cellulose acetate polymer. Part I: Results of thrombosis in experimental aneurysms.

The authors have developed a liquid material for thrombosing aneurysms. This material is a mixture of cellulose acetate polymer and bismuth trioxide dissolved in dimethyl sulfoxide. On contact with blood, the dimethyl sulfoxide diffuses and cellulose acetate polymer forms, which balloons when slowly injected into the blood. The polymer solidifies from surface to core in 5 minutes. Cellulose acetate polymer was injected directly into experimental aneurysms created in 10 dogs; it rapidly hardened in the shape of the aneurysms, completely obliterating them but preserving the parent vessels in all cases. No distal migration of the polymer was seen. The good results of this experimental trial led to a clinical study using a cellulose acetate polymer, as described in Part II.

Direct thrombosis of experimental aneurysms with cellulose acetate polymer (CAP): technical aspects, angiographic follow up, and histological study.

Experimental aneurysms were created using a microsurgical technique to produce anastomosed venous pouches in the bilateral common carotid arteries of 12 dogs. The 24 aneurysms were then thrombosed via an endovascular approach with injection of a cellulose acetate polymer (CAP) solution that the authors have developed for use as a liquid thrombotic material. Angiography performed 1 to 4 weeks after CAP injection revealed complete thrombosis of the aneurysm with patency of the parent artery in 16 aneurysms. Histological analysis disclosed that the aneurysmal orifice in these cases was completely covered with newly formed endothelial cells 2 weeks after CAP thrombosis. Three other aneurysms exhibited parent artery occlusion caused by protrusion of the CAP mass through the aneurysmal orifice into the parent artery; this was thought to be caused by over-injection of the CAP solution. Histological analysis of the remaining five aneurysms, initially shown to have incomplete occlusion, revealed that they each possessed a residual neck that was partially covered with endothelial cells. No rupture of the aneurysms or migration of CAP into the distal arteries was observed. These results suggest that using an endovascular approach, direct thrombosis of cerebral aneurysms with CAP is safe and effective. This technique may prove to be an alternative treatment for such aneurysms. However, there is a potential risk of regrowth or rupture of aneurysms that retain a residual neck and long-term follow-up studies will be required to evaluate this issue.

Direct thrombosis of aneurysms with cellulose acetate polymer. Part II: Preliminary clinical experience.

The authors report the treatment of seven intracranial aneurysms in six patients with direct infusion of cellulose acetate polymer solution, a new liquid thrombotic material. These aneurysms were considered inoperable because of their size or location, or because of the patient's neurological condition. This material avoids the difficulties associated with balloon occlusion, and completely fills even irregularly shaped aneurysms. Cellulose acetate polymer solution hardens in about 5 minutes and remains solid once inside the aneurysm. Because this technique is less invasive than surgery, it can be used for high-risk patients in the acute stage of subarachnoid hemorrhage. Transient motor aphasia occurred in one patient. A small residual neck, which caused rebleeding 3 months after the treatment, remained in another patient. This article describes the new material, the procedure for direct thrombosis, and preliminary clinical results.

Early treatment of subarachnoid hemorrhage after preventing rerupture of an aneurysm.

Twelve patients with Hunt and Hess neurological Grades III to V underwent thrombosis of aneurysms using cellulose acetate polymer within 23 hours of aneurysm rupture. On computerized tomography (CT), nine of these patients had difuse or localized thick subarachnoid blood clots, two had diffuse thin clots and one had intraventricular clots. Immediately after thrombosis, all patients were administered tissue plasminogen activator (TPA) through spinal or ventricular catheters. The pressure of the lumbar cerebrospinal fluid was maintained at 100 to 150 mm H2O. The TPA was given as multiple injections of 2 mg on Day 0 and 1 to 2 mg on the following 1 to 2 days. In two patients the second injection of TPA was not given because of severe brain damage resulting from the initial subarachnoid hemorrhage. Ten patients showed complete clearance of the cisternal clot on CT within 72 hours after thrombosis. Seven partially thrombosed aneurysms and five multiple aneurysms were clipped during delayed surgery. Only one patient experienced mild vasospasm as shown on the follow-up angiogram. Eight patients improved clinically and had a good recovery, two had severe disability, and two died. Urgent thrombosis of a ruptured aneurysm followed by immediate postthrombotic administration of TPA may be a safe and reasonable means of preventing vasospasm and improving patient outcome.

Combined use of cellulose acetate polymer and retrievable platinum coils for the thrombosis of cervical carotid aneurysms.

Cellulose acetate polymer (CAP) solution is a new liquid embolic material, and it has been used clinically for the thrombosis of cerebral aneurysms. The purpose of the study was to test a method of aneurysm treatment. In an experimental model, retrievable interlocking detachable coils (IDCs) were used to create an intraaneurysmal frame or prop and then CAP was injected into 20 experimentally induced canine cervical aneurysms. Intraaneurysmal thrombosis was induced 1 week after aneurysm creation. Complete thrombosis was attempted in 12 aneurysms, and partial thrombosis was attempted in 4. Four other aneurysms served as controls. Follow-up angiography was performed for up to 8 weeks, and with the exception of 4 aneurysms, which were kept for a 2-year long-term follow-up study, the aneurysms were then harvested for histological examination. Thrombosis was successfully achieved in all cases except for 2 enlarged aneurysms that were initially partially thrombosed. No thromboembolism to distal vessels was observed. No compaction or shift of the CAP-IDC complex occurred even after 2 years. Histologically, CAP and IDCs conformed to the massive thrombotic complex without any fragmentation. By creating a frame or prop with retrievable microcoils, we were able to inject the CAP implies a comparison safely and precisely than has been previously reported. Our findings suggest that this method will be useful for the treatment of cerebral aneurysms.

Curative treatment of cerebral arteriovenous malformations by embolisation using cellulose acetate polymer followed by surgical resection.

AIM: To investigate the usefulness of embolising cerebral arteriovenous malformations (AVMs) with a cellulose acetate polymer solution before surgical resection. METHODS: The cases of 12 patients with AVMs treated by embolisation before surgical resection were renewed. Two types of cellulose acetate polymer solutions were used to occlude 40 feeding vessels. All patients underwent surgical resection 1-51 days after embolisation. RESULTS: Reduction of the nidus volume after embolisation ranged from 20% to nearly 100%. Transient neurological deficits occurred in three patients, persistent deficits occurred in one and there were no haemorrhagic complications. All but one arteriovenous malformation were completely resected. Embolisation helped to identify feeding vessels and ease dissection. Histopathological examination of resected specimens disclosed mild inflammatory reactions in the acute stage and no unfavourable granulomatous changes in the chronic stage. CONCLUSION: Embolisation with cellulose acetate polymer solutions followed by surgical resection is safe and efficacious for treating cerebral AVMs.

[Direct embolization with occluding spring embolus for large aneurysm and carotid-cavernous fistula].

The authors describe a technique using occluding spring emboli for direct obliteration of an unclippable large aneurysm, and carotid-cavernous fistula (CCF) which failed to be occluded by transarterial and transvenous approaches. Case 1: This 44 year-old man had a history of head trauma 30 years ago. He was admitted to our department on October 16, 1989, because of an aneurysm incidentally found by a CT scan taken for the examination of his vertigo. Angiograms revealed a large aneurysm at the C3 portion of the right internal carotid artery. A right frontal craniotomy was performed on November 2, 1989, but neck clipping of the aneurysm was impossible, because it was a pseudoaneurysm with quite a fragile neck. Subsequently, fourteen occluding spring emboli were inserted into the aneurysm through a polyethylene catheter directly into the aneurysmal dome. Postoperative angiograms showed almost complete obliteration of the aneurysm with good preservation of the parent artery. Case 2: This 26 year-old woman without a history of head trauma was admitted to our department on May 10, 1989, complaining of right conjunctival injection and exophthalmos. Angiograms revealed a spontaneous CCF which had a single orifice at the C4 portion of the right internal carotid artery and drained through the superior ophthalmic vein and inferior petrosal sinus. Initially, transarterial and transvenous approaches were tried, but the attempts were unsuccessful. Subsequently, a right frontotemporal craniotomy was performed on August 8, 1989, and 27 occluding spring emboli were placed into the cavernous sinus through a polyethylene catheter which had been inserted directly.(ABSTRACT TRUNCATED AT 250 WORDS)

Endovascular treatment of cerebral aneurysms: An in vitro study with detachable platinum coils and tricellulose acetate polymer.

OBJECTIVE: The purpose of our experimental study was to determine the effectiveness of filling the cavity of in vitro aneurysms with detachable platinum coils and the combination of detachable platinum coils and liquid embolic agent. MATERIALS AND METHODS: Silicone aneurysm models were connected to a circulatory system to simulate arterial flow. A microcatheter was used to introduce detachable coils into the aneurysm cavities. First, platinum coils were introduced until the point of minimal dense packing, indicated by aneurysmal circulatory exclusion. Packing was continued up to maximal dense packing, indicated by protrusion of the coil into the parent artery. Volumetric ratios (coil volume-aneurysm volume) were calculated for minimal and maximal dense packing. Then, after purposeful undercoiling of aneurysm models, a micropump system was used to fill the aneurysm by stepwise injection of tricellulose acetate polymer through the coil mesh until angiographic aneurysm exclusion was completed. The volumetric ratios of maximal packing with coils and tricellulose acetate polymer in relation to the aneurysm volume were calculated. RESULTS: Maximal dense packing ratios with coils (mean, 32.5%; standard deviation [SD], 3%) were slightly higher than those with the minimal dense packing (mean, 28. 2%; SD, 3%) but were always less than 37%. The ratios of packing with the combined use of coils and tricellulose acetate polymer were greater than 100% (mean, 124.4%; SD, 15%). CONCLUSION: Knowledge of the volumetric ratio of maximal dense packing was useful for effective filling with coils and tricellulose acetate polymer. The combined use of coils and liquid polymer appeared more effective than the use of coils alone for the complete occlusion of the aneurysm lumen.