Hearing Disturbance After Transvenous Embolization of Dural Arteriovenous Fistula Involving the Anterior Condylar Confluence : case report

Dural arteriovenous fistulas (AVFs) commonly occur in the cavernous sinus, transverse sinus, and sigmoid sinus. Recently, dural AVFs involving anterior condylar confluence (ACC dural AVFs) have also been recognized and treated mostly by transvenous embolization (TVE)1,4-7,9-12). Since the exact location of the fistula can now be determined with three-dimensional angiography using recently developed digital subtraction angiography routines, selective TVE of the fistula with coils has been performed. One of the main complications of TVE of ACC dural AVFs is hypoglossal nerve palsy, when the dural AVF involves both the ACC and the hypoglossal canal6,7,9,10,12). Here we present a case of hearing disturbance following TVE of the ACC dural AVF, which is a rare complication of this procedure.


Introduction
Dural arteriovenous fistulas (AVFs) commonly occur in the cavernous sinus, transverse sinus, and sigmoid sinus.Recently, dural AVFs involving anterior condylar confluence (ACC dural AVFs) have also been recognized and treated mostly by transvenous embolization (TVE) 1,[4][5][6][7][9][10][11][12] . Since he exact location of the fistula can now be determined with three-dimensional angiography using recently developed digital subtraction angiography routines, selective TVE of the fistula with coils has been performed.One of the main complications of TVE of ACC dural AVFs is hypoglossal nerve palsy, when the dural AVF involves both the ACC and the hypoglossal canal 6,7,9,10,12) .Here we present a case of hearing disturbance following TVE of the ACC dural AVF, which is a rare complication of this procedure.

Case report
A 61-year-old man suffered from idiopathic left pulsatile tinnitus three months ago but it disappeared in a month.
Occasionally  We emphasize here that TVE of dural AVF should be performed by occlusion of the fistula or drainage site (vein) involving the fistula, and not by occlusion of the drainage site (vein) alone.Placement of coils in an inadequate site may cause worsening of venous hypertension and may lead to an unfavorable outcome 9) .
The IPS, especially, should not be occluded because it forms a tract of venous circulation between the cochlea and vestibular apparatus.Understanding the venous circulation of the cochlea and vestibular apparatus is mandatory for safe treatment of ACC dural AVF.  26 : 1955-1959, 2005.

Conclusion
appeared.He was referred to our hospital with suspected left carotid-cavernous fistula (CCF).Neurological findings Case Report Hearing Disturbance After Transvenous Embolization of Dural Arteriovenous Fistula Involving the Anterior Condylar Confluence: case report were chemosis of the left eye, left abducens nerve palsy, and increased intraocular pressure (30 mmHg).Dural AVF involving the left cavernous sinus (CS) was suspected from the medical history and neurological findings.Source images of computed tomography and magnetic resonance imaging after contrast enhancement revealed small multiple arteries at the outer side of the left hypoglossal canal (Fig. 1A, B).Left external carotid angiography revealed the presence of a dural AVF adjacent to the left jugular bulb, which was supplied mainly by the left ascending pharyngeal artery (Fig. 2, 3A, B).The right ascending pharyngeal artery was not involved.The fistula was located at the anterior condylar confluence (ACC).The drainage route was the left superior ophthalmic vein (SOV) via the left inferior petrosal sinus (IPS) and CS retrogradely and no other drainage pathway was identified on angiography.TVE was performed via the right femoral vein.Using a 5 Fr.guiding catheter positioned in the left jugular vein, we first attempted to insert a microcatheter directly into the fistula at the ACC, but failed.Then we attempted to advance it from the jugular vein through the IPS into the fistula at the ACC, but failed again.Therefore the microcatheter was placed into the left IPS, which we occluded with detachable coils since it seemed to be the only drainage route from the ACC.Angiography still showed a small residual fistula, which we treated with transarterial embolization from the left pharyngeal artery using Spongel (Yamanouchi, Tokyo, Japan).The final angiography revealed a minimal residual ACC dural AVF with almost no drainage (Fig. 3C, D).Though his left ocular symptoms (conjunctival injection, chemosis) improved within a few days, a left neurosensory hearing disturbance occurred 3 days after the treatment (postoperative day 3; POD3).He was immediately treated with steroids and systemic heparinization.Mild dysphagia and dysarthria due to hypoglossal nerve palsy occurred POD6.Furthermore episodes of peripheral vertigo occurred POD16 and 26, both of which improved within days.Angiography demonstrated complete obliteration of the ACC dural AVF 1 month after the treatment (Fig. 4).Though the left hypoglossal nerve palsy and vertigo disappeared within 1 month, hearing disturbance did not improve and remained 2 years after the treatment． to the rapid technological progress in digital subtraction angiography devices.Selective three-dimensional angiography and tomographic imaging enables us to understand the angioarchitecture of the vascular lesions accurately, especially in the craniocervical region 11) .Using this knowledge, most cases of ACC dural AVF have been treated by selective TVE of the fistula with less coils and a shorter operative time than before.

Fig. 1
Fig. 1Source images of computed tomography (A) and magnetic resonance imaging after contrast enhancement (B) revealed small multiple arteries (arrows) at the outer side of the left hypoglossal canal.
Fig. 2 Frontal (A) and lateral (B) views of the left external carotid artery angiogram showing a dural AVF adjacent to the jugular bulb with retrograde venous drainage to the SOV via the left IPS and left cavernous sinus.Antegrade venous drainage to the jugular vein is hardly seen.

Fig. 3
Fig. 3 Frontal (A) and lateral (B) views of an angiogram of the left ascending pharyngeal artery showing a dural AVF adjacent to the jugular bulb with retrograde venous drainage to the SOV via left IPS.Antegrade venous drainage to the jugular vein is hardly seen.Frontal (C) and lateral (D) views of an angiogram of the left external carotid artery after embolization of the left IPS showing a residual dural AVF adjacent to the jugular bulb without any venous drainage.AVF: arteriovenous fistula, IPS: inferior petrosal sinus, SOV: superior ophthalmic vein Kojima T, Miyachi S: Diagnosis and treatment of dural arteriovenous fistula of anterior condylar confluent.16: 731-737, 2006.７)Miyachi S, Ohshima T, Izumi T, et al: Dural arteriovenous fistula at the anterior condylar confluence.14 : 303-311, 2008.８)Nomura K: Atlas of otology; form and measurement, the 3rd edition.Tokyo, Springer, 2008, 215-216.９)Okahara M, Kiyosue H, Tanoue S: Selective transvenous embolization of dural arteriovenous fistulas involving the hypoglossal canal.13: 59-66, 2007.10)Robert Ernst, Robert Bulas, Thomas Tomsick: Three cases of dural arteriovenous fistula of the anterior condylar vein within the hypoglossal canal.20 : 2016-2020, 1999.11)San Millan Ruiz D, Gailloud P, Rufenacht DA: The craniocervical venous system in relation to cerebral venous drainage.23: 1500-1508, 2002.12)Tanoue S, Goto K, Oota S: Endovascular treatment for dural arteriovenous fistula of the anterior condylar vein with unusual venous drainage: report of two cases.
The authors declare that they have no conflict of interest.