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Posterior Fossa Arteriovenous Fistula After Guglielmi Detachable Coils Embolization of ruptured vertebral artery dissecting aneurysm : A Case Report

Masao Nakatsuka1), Shirou Mizuno1), Atsushi Uchida1), Mitsuhito Mase2), Kenichi Watanabe3)

Addresses
1) Department of Neurosurgery, Chita Kousei Hospital 81-6 Nishitani Kouwa Mihama-chou Chita-gun Aichi, JAPAN 470-2404
TEL +81-569-82-0395, FAX +81-569-82-4333
2) Department of Neurosurgery, Nagoya City University 1 Kawasumi Mizuho-chou Mizuho-ku Nagoya Aichi, JAPAN 467-8602
TEL +81-52-853-8286, FAX +81-52-851-5541
3) Department of Radiology, Higashi Municipal Hospital of Nagoya 1 Wakamizu Chikusa-ku Nagoya Aichi, JAPAN 464-8547
TEL +81-52-721-7171, FAX +81-52-721-1308

Summary
Acquired AVF commonly develops secondary to sinus thrombosis or trauma. Although, there have been reports of the delayed development of AVF after open surgery, it has not been reported after interventional radiology. Herewith, we report a patient with posterior fossa arteriovenous fistula developed after interventional radiology. In a 52-year-old man with subarachnoid hemorrhage, angiography showed a dissecting aneurysm of the left vertebral artery and hypoplasia of the left transverse sinus. The aneurysm was embolized using Gugliemli detachable coils. Follow-up angiography demonstrated an arteriovenous fistula arising from the posterior inferior cerebellar artery. Because all AVFs have the potential to cause intracerebral hemorrhage, careful follow-up is needed . Consequently, this case emphasizes the potential risk of late AVF developing after interventional radiology.
Interpretation: Interventional radiology may cause arteriovenous fistulas in patients with sinus hypoplasia.

Key Words: arteriovenous fistula, Guglielmi detachable coil, dissecting aneurysm

Introduction
Recently, Guglielmi detachable coils (GDC) have been increasingly used to treat ruptured and unruptured aneurysms. We encountered a patient in whom a posterior fossa arteriovenous fistula (AVF) developed after GDC embolization of a ruptured dissecting aneurysm of the vertebral artery(VA).

Case Report
A 52-year-old man was admitted with severe headache, and computed tomography demonstrated subarachnoid hemorrhage. At 3.5 hours after the onset, cerebral angiography showed a left VA dissecting aneurysm with extravasation (Fig.1 A) and hypoplasia of the left transverse sinus (Fig.1 B). The pseudolumen and proximal VA beyond the posterior inferior cerebellar artery (PICA) were embolized using GDC (Fig.1 C). Immediately after embolization, there was no AVF (Fig.1 D). However, repeat angiography after 7 days demonstrated a posterior fossa AVF arising from the PICA (Fig.1 E). He was discharged without neurological deficits and has remained asymptomatic for 12 months. Repeat angiography after 1, 3, and 6 months showed no changes of the AVF. However, the 12-month angiogram demonstrated slower flow in the AVF and revealed the course of the shunt (Fig.1 F-K); from the PICA to the vein of the lateral recess of the fourth ventricle and from the petrosal vein to the superior petrosal vein.

Discussion
Acquired AVF commonly develops secondary to sinus thrombosis or trauma 1). Although, there have been reports of the delayed development of AVF after open surgery 1) 2) 3), it has not been reported after interventional radiology. In most patients with postoperative AVF, surgery sacrificed the sigmoid sinus or superior petrosal sinus 2) 3). Our patient had pre-existing hypoplasia of the left transverse sinus. Nabors and coworkers reported two cases of postoperative dural AVF occurring at the site of suboccipital craniectomy without sinus sacrifice, and suggested that the increased arterial supply from the scalp and muscular vessels was responsible 1). After our patient's left VA was embolized, increased perfusion of the left PICA might have caused the AVF in a similar manner. According to Chaudhary and coworkers 4), AVFs represent the pathological opening-up of physiological arteriovenous shunts in the dural walls of the venous sinuses, and the increased arterial supply may have opened such physiological shunts in our patient. In any event, this case emphasizes the potential risk of late AVF developing after interventional radiology.
Our patient was treated conservatively because he had no symptoms, and no angiographic progression. In fact, there was a tendency for spontaneous involution of the AVF over time. However, careful follow-up is needed because all AVFs have the potential to cause intracerebral hemorrhage.

Legends
Fig.1 Initial arteriogram; sequential changes of arteriogram. A: LAO-dissecting aneurysm of the left VA. B: A-P (venous phase)-left transverse sinus hypoplasia. C,D: LAO-after embolization of the aneurysm. E: Left vertebral arteriogram at 7 days after embolization showing the fistula in the arterial phase. F-K: Angiography after 12 months-lateral views; sequential changes of arteriogram. I, J, and K are enlarged views of F, G, and H, respectively. The fistula is demonstrated in a later phase than in the previous angiograms. Arrows show the arteriovenous shunts running from the PICA to the vein of the lateral recess of the fourth ventricle and from the petrosal vein to the superior petrosal vein.

References
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2) Sasaki T, Hoya K, Kinone K, Kirino T. Postsurgical development of dural arteriovenous malformations after transpetrosal and transtentorial operations. Case report. Neurosurgery 1995; 37: 820-825
3) Sasaki T, Morimoto T, Nakase H, Kakizaki T, Nagata K. Dural arteriovenous fistula of the posterior fossa developing after surgical occlusion of the sigmoid sinus. J Neurosurg 1996; 84: 113-118
4) Chaudhary MY, Sachdev VP, Cho SH, Weitzer, Jr. I , Puljic S, Huang YP. Dural arteriovenous malformation of the major venous sinuses: an acquired lesion. AJNR 1982; 3: 13-19
5) Cognarg C, Houdart E, Casasco A, Gabrillargues J, Chiras J, Merland JJ. Long-term changes in intracranial dural arteriovenous fistulae leading to worsening in the type of venous drainage. Neuroradiology 1997; 39: 59-66

Nagoya City University
Medical School