Transcatheter obliteration of a cerebellar arteriovenous fistula with platinum coils.

A single-hole arteriovenous fistula (A VF) consists of a solitary abnormal communication between an artery and a vein without an intervening capillary network. An AVF must be distinguished from an arteriovenous malformation (A VM), which is composed of a complex network of arteriovenous connections (nidus or core). Most AVFs develop as a result of trauma; those between the internal carotid artery and the cavernous sinus (carotid-cavernous fistulas) are the most commonly encountered [1 ). Spontaneous (congenital or acquired) AVFs are uncommon and may be seen in children (AVFs associated with vein of Galen malformations) or in association with angiodysplasia in patients with neurofibromatosis and Ehlers-Danlos syndrome [2). Single-hole AVFs are also encountered in the external carotid circulation [3, 4] . Congenital AVFs located in the posterior fossa are extremely rare [5). Because surgical treatment for solitary AVFs is difficult and often unsuccessful, transvascular embolization therapy has become increasingly important. Both balloons and platinum coils have been used to treat supratentorial AVFs [6). Balloon embolization of a posterior fossa A VF has also been described [5). We present a case of a single-hole posterior fossa AVF fed by a tortuous right superior cerebellar artery (SCA) in which dilated draining veins displaced the pons, resulting in a progressive neurologic deficit related to a circulatory steal and direct compression of the brainstem. The fistula and the arterial feeder were successfully occluded with platinum minicoils delivered through a Tracker microcatheter of variable stiffness (Target Therapeutics, Los Angeles, CA). Dramatic clinical improvement was noted toward the end of the procedure. The fistula was completely closed, and clinical improvement continued over the next several months. Postprocedural CT and follow-up angiography at 6 months revealed thrombosis of the large compressive varices and persistent fistula closure. We believe this case to be the first successful coil embolization of a posterior fossa AVF. The immediate neurologic improvement seen after fistula closure likely resulted from correction of the circulatory steal and brainstem decompression.