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Embolization treatment of 16 patients with dominant-hemisphere arteriovenous malformations (AVMs) is described. This group was selected from 50 patients with brain AVMs embolized with isobutyl 2-cyanoacrylate (IBC-2) over a period of 3 years. All 16 AVMs were cortical in location; six involved the rolandic and speech areas, and four had a deep component. Ten AVMs were embolized through a transfemoral approach, an intraoperative approach was used for four cases, and a combined transfemoral/intraoperative approach was used in two cases. Complete obliteration of the AVM was obtained in one case. Partial obliteration and complete surgical resection was obtained in three cases. Obliteration of 70%-95% of the AVM was obtained in six cases and 45%-70% of the AVM was obliterated in six cases. IBC-2 embolization of the venous drainage was observed in three cases. After embolization, eight patients remained neurologically unchanged. Three patients had mild neurologic deficits that resolved completely within 48 hr; one had a deficit that cleared up 1 week later; and one had a deficit that disappeared within 6 months. In three patients a mild permanent neurologic deficit was evident 6 months after embolization.

This study evaluated the long-term angiographic results in large cerebral arteriovenous malformations (AVMs) partially embolized with isobutyl-2-cyanoacrylate. Preembolization, immediate postembolization, and long-term follow-up angiograms were performed in 30 large, partially embolized brain AVMs. Particular attention was paid to the relative size of the residual AVM nidus and the embolized arterial feeders, to recruitment of new feeders, to the size of residual draining veins, and to the speed of arteriovenous shunt. Nine cases with less than 50% AVM nidus obliteration showed no significant morphologic changes. In 18 cases with 50-75% obliteration of the AVM nidus, 11 (61.1%) showed no significant changes, six (33.3%) showed enlargement of the AVM nidus, and one (5.5%) evolved to complete angiographic obliteration. In three cases with 75-99% AVM nidus obliteration, one remained unchanged, one showed an increase in the size of the AVM nidus, and one evolved to complete obliteration. Evaluation by plain film, CT, and cerebral angiography of the isobutyl-2-cyanoacrylate deposits showed that when the polymer was positioned predominantly in arterial feeders there was invariably reconstitution of the AVM nidus through leptomeningeal, deep medullary, and/or dural collaterals. This phenomenon did not occur when the isobutyl-2-cyanoacrylate was deposited mainly in the AVM nidus.

Despite the development of new alternative embolic agents, the endovascular treatment of brain arteriovenous malformations continues to frequently require the use of cyanoacrylic glue, especially in situations where particulate or sclerosing agents are ineffective, such as when flow is very rapid or fistulous. Because isobutyl 2-cyanoacrylate (IBCA), the most commonly used embolic glue, is no longer available or manufactured, a real need exists for an alternative fast polymerizing agent. In vivo and in vitro studies were performed to compare IBCA with n-butyl 2-cyanoacrylate (NBCA, supplied as Histoacryl Blue), a tissue adhesive approved for surgical use in some countries. Polymerization times in static plasma were compared, and the effect of the addition of iophendylate oil or glacial acetic acid on polymerization was assessed. Polymerization times in vivo were compared after intraarterial injection into the internal carotid artery in pigs using a standardized technique. The histopathologic reactions to each glue in the embolized pig rete were assessed and compared over a period of 0-60 days after embolization. Our results show that while NBCA polymerization is demonstrably faster than IBCA in vitro, intraarterial injections of each glue show no significant difference in polymerization times. Like IBCA, NBCA polymerization can be predictably prolonged by the addition of oil or glacial acetic acid, though the effect is less for NBCA. Histopathologic reactions were similar, with acute vasculitis observed, becoming chronic and granulomatous after about 1 month. Both glues showed frequent foci of extravascular extrusion through the embolized rete and recanalization of previously occluded embolized vessels. We conclude that NBCA has clinical and biologic behaviors similar to IBCA, and therefore should be an acceptable alternative to IBCA for intravascular use.

Eight patients with arteriovenous malformations (AVMs) in the basal ganglionic and deep parietooccipital regions and one patient with an AVM in the shoulder region showed resorption of the isobutyl 2-cyanoacrylate cast and recanalization of the arteries after delayed follow-up angiography. All the AVMs were large, had multiple arterial pedicles, and revealed significant obliteration of the AVM immediately after embolotherapy. Although a 50-75% obliteration was achieved immediately after embolization, follow-up angiography 6-20 months later revealed almost the original status. The residual bucrylate cast was disproportionately small compared with the recanalized malformation in seven patients, while in two patients there was no evidence of bucrylate on plain films. Degradation of bucrylate probably is due to the lysosomal activity of the endothelial cells. The results from our nine patients with some degree of resorption of isobutyl 2-cyanoacrylate and six with recanalized AVMs 6-20 months after embolization suggest that operable AVMs should be excised soon after embolotherapy and inoperable AVMs should be embolized as completely as possible.

Transfemoral and intraoperative embolization of arteriovenous malformations (AVMs) of the brain with isobutyl-2 cyanoacrylate may achieve complete and permanent occlusion of the AVMs. The preembolization superselective angiogram is an important source of information to decrease potential technical or clinical complications while seeking that goal. The information obtained from the angiogram of each individual feeder may be classified as anatomical, dynamic, and functional. This angiogram is performed either through a calibrated-leak balloon glued to a Silastic tubing, which is capable of negotiating cortical arterial curves, or through a short catheter directly placed into a feeder at surgery. In 64 patients, 175 preembolization superselective angiograms were obtained. Of those, 105 were obtained using the transfemoral technique, and 70 were obtained by direct catheterization after a craniotomy. Complications occurred in eight patients with only one permanent injury. Transient neurologic deficit occurred in five patients. One patient developed a permanent left monoplegia and one patient a subarachnoid hemorrhage without permanent neurologic deficit. In one patient, a delayed intracerebral hemorrhage produced a right hemiplegia and aphasia. The patient fully recovered in 6 months.

The role of embolization in the management of brain arteriovenous malformations remains controversial. The benefits of embolization alone are not clear and surgical removal may be technically difficult or impossible in many cases. In an attempt to facilitate surgical removal, we performed preoperative embolization in 15 cases using a mixture of isobutyl-2 cyanoacrylate and glacial acetic acid. In one case, a mixture of polyvinyl alcohol particles, microfibrillar collagen, and 30% ethanol was used. In 10 of these cases the surgeon felt that the embolization significantly aided the operative removal by decreasing blood loss, reducing the size of draining veins, and removing portions of the nidus itself. In no patient did the embolization result in an unanticipated significant neurologic deficit. The major role for embolization in the management of brain arteriovenous malformations may be as an aid to surgical removal.

Embolization of brain arteriovenous malformations (AVMs) with isobutyl 2-cyanoacrylate (IBCA) is an alternative to surgical treatment when dealing with large AVMs with multiple arterial feeders. The deposition of IBCA in the nidus of the AVM may produce an active and progressive thrombosis that may lead to complete occlusion of the nidus and/or to progressive thrombosis of the draining veins. Four clinical examples of progressive thrombosis after IBCA embolization are demonstrated, including two cases in which late follow-up angiography showed complete obliteration of a partly embolized AVM.