Nidus Embolization for Large Arterovenous Malformation Prior to Surgical Excision

-Report of two cases and indication of artificial embolization-

Abstract

Two cases of large arteriovenous malformations successfully removed following artificial nidus embolization by silastic spheres are reported.
Case 1: A 27-year-old housewife was admitted to our department with the chief complaint of episodes similar to alexia, apraxia and aphasia lasting for a few minutes, which started four years prior to the admission. Neurological examination at admission showed no abnormalities. A left internal carotid angiogram taken at admission showed the presence of a large arteriovenous malformation in the left parieto-temporo-occipital region fed by three branches of the left middle cerebral artery and two branches of the left posterior cerebral artery. To facilitate successful excision without neurological deficits, nidus embolization by silastic spheres was performed via the left internal carotid and the left vertebral arteries. The nidus was significantly reduced with decreased diameters of feeding arteries on the angiogram made following nidus embolization. Total removal of the nidus was successfully performed 15 days following completion of embolization, and it was found that separation of the nidus was much easier compared to a surgical procedure without preoperative embolization mainly because of reduced tension of each vessel into the nidus. The postoperative course was uneventful.
Case 2: A 27-year-old male was admitted to our department with three episodes of subarachnoid hemorrhage. He was neurologically asymptomatic at admission. A right internal carotid angiogram taken at admission showed the presence of a large arteriovenous malformation in the medial portion of the right frontoparietal lobe and corpus callosum mainly fed by the right pericallosal artery. Nidus embolization by silastic spheres was planned for making surgical removal easier. To prevent the Silastic spheres from straying into the right middle cerebral artery, a balloon, introduced into the M₁, was inflated for a few minutes, during which time in jection of the Silastic spheres was performed via the right internal carotid artery. The nidus was significantly reduced and its total removal was successfully done 28 days following the embolization.
The authors stressed the efficacy of nidus embolization for large arteriovenous malformation prior to surgical excision and discussed indications of preoperative artificial embolization.