Otology & Neurotology 36:e115Ye116 Ó 2014, Otology & Neurotology, Inc.
Imaging Case of the Month
Pulsatile Tinnitus Secondary to a Dural Arteriovenous Fistula *Ryan T. Fitzgerald, †Rachel Pollitzer, *Rohan S. Samant, *Manoj Kumar, *Raghu H. Ramakrishnaiah, *Adewumi Amole, *Mehmet S. Akdol, and *Edgardo J. Angtuaco *Division of Neuroradiology, Department of Radiology, University of Arkansas for Medical Sciences; and ÞUniversity of Arkansas for Medical Sciences, College of Medicine, Little Rock, Arkansas, U.S.A.
A 51-year-old woman presented with a 3-month history of worsening unilateral pulsatile tinnitus, left ear pain, and vertigo. She reported no history of trauma. Otoscopic exam, audiometry, and tympanometry were normal. An initial magnetic resonance imaging (MRI) demonstrated asymmetrically diminished caliber of the left transverse/sigmoid sinus (Fig. 1A) relative to the normal right sinus (Fig. 1B). Axial contrast-enhanced T1-weighted imaging revealed ‘‘shaggy,’’ ill-defined transverse sinus margins, and foci of linear enhancement intermixed with flow voids within the adjacent temporal diploic space (Fig. 2A). Computed tomography (CT) of temporal bones revealed prominent transosseous channels within the left temporal, parietal, and occipital calvaria (Fig. 2B). Such CT and MRI findings were suggestive of a dural arteriovenous fistula (DAVF), and a catheter angiogram was obtained revealing abnormal vasculature along the left transverse sinus and early filling of the left sigmoid sinus confirming the diagnosis of DAVF (Fig. 2C). Endovascular embolization was performed using Onyx (eve3, Irvine, California) with uncomplicated closure of greater than 50% of the DAVF. After the procedure, the patient reported resolution of tinnitus and vertigo and marked improvement of her otalgia.
treatable causes, many of which are vascular in origin. Structural or anatomic causes of pulsatile tinnitus have been reported to occur in 44% to 91% of cases (2). Aberrant or variant vascular anatomy, arterial or venous stenoses, or various high-flow vascular lesions including DAVF may contribute to pulsatile tinnitus through transfer of flow-related vibration to the inner ear (1). Dural arteriovenous fistulas (DAVFs) consist of shunts between dural arteries and venous sinuses and adjacent meningeal/cortical venous vasculature. Location adjacent to dural sinuses, lack of a parenchymal nidus, and the presence of dural arterial supply distinguish these lesions from arteriovenous malformations, which constitute the primary differential diagnosis of the lesion. DAVFs most commonly arise at the transverse, sigmoid, and cavernous sinuses and are typically considered to be idiopathic in etiology but may occur in the setting of previous craniotomy, trauma, or dural venous sinus thrombosis leading to the formation of an arteriovenous shunt (3). In addition to pulsatile tinnitus, patients with DAVF may also experience ophthalmoplegia, proptosis, chemosis, retro-orbital pain, decreased visual acuity, intracranial hemorrhage, and various other neurologic symptoms (3). Imaging strategies for the patient presenting with pulsatile tinnitus are ideally tailored for the detection of potentially treatable vascular etiologies. CT angiography (CTA) is now considered to be the initial imaging examination of choice, as current CTA techniques provide excellent depiction of osseous anatomy of the temporal bone in addition to robust assessment for various intratemporal and extratemporal vascular pathologies, including DAVF. Nonenhanced CT of the temporal bone may reveal findings suggestive of DAVF such as transosseous vascular channels (Fig. 2), which are specific for DAVF (86% specificity), although suboptimally sensitive (2). Precontrast and postcontrast MRI and MR angiography provides a complimentary modality for the detection of abnormal vascular pathology associated with
DISCUSSION Pulsatile tinnitus is reported to occur in 4% of all patients presenting with a complaint of tinnitus (1). In contrast to nonpulsatile tinnitus, differential considerations for pulsatile tinnitus include an array of identifiable and readily Address correspondence and reprint requests to Ryan T. Fitzgerald, M.D., Department of Radiology, Neuroradiology Division, University of Arkansas for Medical Sciences, Slot 556, 4301 W. Markham St., Little Rock, AR 72205; E-mail: [email protected] The authors disclose no conflicts of interest.
e115
Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
e116
R. T. FITZGERALD ET AL.
FIG. 1. Sagittal contrast-enhanced T1-weighted MR images demonstrates ‘‘shaggy’’ margins and heterogeneous internal enhancement at the junction of the left transverse and sigmoid sinuses (arrow, A) relative to the normal right sinus (arrow, B).
FIG. 2. Axial contrast-enhanced T1-weighted MR image shows linear and ill-defined enhancement as well as several small flow voids within the diploid space and cortex of the temporal calvarium (arrow, A) representative of transosseous vascular channels. On axial CT, numerous curvilinear areas of lucency within the left temporal calvarium (arrow, B) correspond to the enhancing vessels seen on MRI. Such vessels are also visible by catheter angiography at the site of fistula (circle, C), which leads to early arterial-phase filling of the left sigmoid sinus (dashed arrow, C) characteristic of a DAVF.
the dural sinuses, although at the expense of bony anatomy, which is poorly delineated by MRI. Additional findings suggestive of DAVF on CTA and MRI include asymmetric arterial feeding vessels, ‘‘shaggy’’ or illdefined dural sinus margins, or dural sinus stenosis/ occlusion. Catheter angiography continues to be used in the setting of negative noninvasive workup with high clinical suspicion of DAVF and remains the gold standard for DAVF characterization and treatment planning. Recent work suggests that 4D contrast-enhanced MRA can provide comparable delineation of DAVF anatomy to that of catheter angiography (4).
REFERENCES 1. Liyanage SH, Singh A, Savundra P, et al. Pulsatile tinnitus. J Laryngol Otol 2005;120:93Y7. 2. Narvid J, Do HM, Blevins NH, et al. CT angiography as a screening tool for dural arteriovenous fistula in patients with pulsatile tinnitus: feasibility and test characteristics. Am J Neuroradiol 2011;32:446Y53. doi:10.3174/ajnr.A2328. 3. Gandhi D, Chen J, Pearl M, et al. Intracranial dural arteriovenous fistulas: classification, imaging findings, and treatment. Am J Neuroradiol 2012;33:1007Y13. doi:10.3174/ajnr.A2798. 4. Nishimura S, Hirai T, Sasao A, et al. Evaluation of dural arteriovenous fistulas with 4D contrast-enhanced MR angiography at 3T. Am J Neuroradiol 2010;31:80Y5. doi:10.3174/ajnr.A1898.
Otology & Neurotology, Vol. 36, No. 7, 2015
Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
Imaging Case of the Month
Pulsatile Tinnitus Secondary to a Dural Arteriovenous Fistula *Ryan T. Fitzgerald, †Rachel Pollitzer, *Rohan S. Samant, *Manoj Kumar, *Raghu H. Ramakrishnaiah, *Adewumi Amole, *Mehmet S. Akdol, and *Edgardo J. Angtuaco *Division of Neuroradiology, Department of Radiology, University of Arkansas for Medical Sciences; and ÞUniversity of Arkansas for Medical Sciences, College of Medicine, Little Rock, Arkansas, U.S.A.
A 51-year-old woman presented with a 3-month history of worsening unilateral pulsatile tinnitus, left ear pain, and vertigo. She reported no history of trauma. Otoscopic exam, audiometry, and tympanometry were normal. An initial magnetic resonance imaging (MRI) demonstrated asymmetrically diminished caliber of the left transverse/sigmoid sinus (Fig. 1A) relative to the normal right sinus (Fig. 1B). Axial contrast-enhanced T1-weighted imaging revealed ‘‘shaggy,’’ ill-defined transverse sinus margins, and foci of linear enhancement intermixed with flow voids within the adjacent temporal diploic space (Fig. 2A). Computed tomography (CT) of temporal bones revealed prominent transosseous channels within the left temporal, parietal, and occipital calvaria (Fig. 2B). Such CT and MRI findings were suggestive of a dural arteriovenous fistula (DAVF), and a catheter angiogram was obtained revealing abnormal vasculature along the left transverse sinus and early filling of the left sigmoid sinus confirming the diagnosis of DAVF (Fig. 2C). Endovascular embolization was performed using Onyx (eve3, Irvine, California) with uncomplicated closure of greater than 50% of the DAVF. After the procedure, the patient reported resolution of tinnitus and vertigo and marked improvement of her otalgia.
treatable causes, many of which are vascular in origin. Structural or anatomic causes of pulsatile tinnitus have been reported to occur in 44% to 91% of cases (2). Aberrant or variant vascular anatomy, arterial or venous stenoses, or various high-flow vascular lesions including DAVF may contribute to pulsatile tinnitus through transfer of flow-related vibration to the inner ear (1). Dural arteriovenous fistulas (DAVFs) consist of shunts between dural arteries and venous sinuses and adjacent meningeal/cortical venous vasculature. Location adjacent to dural sinuses, lack of a parenchymal nidus, and the presence of dural arterial supply distinguish these lesions from arteriovenous malformations, which constitute the primary differential diagnosis of the lesion. DAVFs most commonly arise at the transverse, sigmoid, and cavernous sinuses and are typically considered to be idiopathic in etiology but may occur in the setting of previous craniotomy, trauma, or dural venous sinus thrombosis leading to the formation of an arteriovenous shunt (3). In addition to pulsatile tinnitus, patients with DAVF may also experience ophthalmoplegia, proptosis, chemosis, retro-orbital pain, decreased visual acuity, intracranial hemorrhage, and various other neurologic symptoms (3). Imaging strategies for the patient presenting with pulsatile tinnitus are ideally tailored for the detection of potentially treatable vascular etiologies. CT angiography (CTA) is now considered to be the initial imaging examination of choice, as current CTA techniques provide excellent depiction of osseous anatomy of the temporal bone in addition to robust assessment for various intratemporal and extratemporal vascular pathologies, including DAVF. Nonenhanced CT of the temporal bone may reveal findings suggestive of DAVF such as transosseous vascular channels (Fig. 2), which are specific for DAVF (86% specificity), although suboptimally sensitive (2). Precontrast and postcontrast MRI and MR angiography provides a complimentary modality for the detection of abnormal vascular pathology associated with
DISCUSSION Pulsatile tinnitus is reported to occur in 4% of all patients presenting with a complaint of tinnitus (1). In contrast to nonpulsatile tinnitus, differential considerations for pulsatile tinnitus include an array of identifiable and readily Address correspondence and reprint requests to Ryan T. Fitzgerald, M.D., Department of Radiology, Neuroradiology Division, University of Arkansas for Medical Sciences, Slot 556, 4301 W. Markham St., Little Rock, AR 72205; E-mail: [email protected] The authors disclose no conflicts of interest.
e115
Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
e116
R. T. FITZGERALD ET AL.
FIG. 1. Sagittal contrast-enhanced T1-weighted MR images demonstrates ‘‘shaggy’’ margins and heterogeneous internal enhancement at the junction of the left transverse and sigmoid sinuses (arrow, A) relative to the normal right sinus (arrow, B).
FIG. 2. Axial contrast-enhanced T1-weighted MR image shows linear and ill-defined enhancement as well as several small flow voids within the diploid space and cortex of the temporal calvarium (arrow, A) representative of transosseous vascular channels. On axial CT, numerous curvilinear areas of lucency within the left temporal calvarium (arrow, B) correspond to the enhancing vessels seen on MRI. Such vessels are also visible by catheter angiography at the site of fistula (circle, C), which leads to early arterial-phase filling of the left sigmoid sinus (dashed arrow, C) characteristic of a DAVF.
the dural sinuses, although at the expense of bony anatomy, which is poorly delineated by MRI. Additional findings suggestive of DAVF on CTA and MRI include asymmetric arterial feeding vessels, ‘‘shaggy’’ or illdefined dural sinus margins, or dural sinus stenosis/ occlusion. Catheter angiography continues to be used in the setting of negative noninvasive workup with high clinical suspicion of DAVF and remains the gold standard for DAVF characterization and treatment planning. Recent work suggests that 4D contrast-enhanced MRA can provide comparable delineation of DAVF anatomy to that of catheter angiography (4).
REFERENCES 1. Liyanage SH, Singh A, Savundra P, et al. Pulsatile tinnitus. J Laryngol Otol 2005;120:93Y7. 2. Narvid J, Do HM, Blevins NH, et al. CT angiography as a screening tool for dural arteriovenous fistula in patients with pulsatile tinnitus: feasibility and test characteristics. Am J Neuroradiol 2011;32:446Y53. doi:10.3174/ajnr.A2328. 3. Gandhi D, Chen J, Pearl M, et al. Intracranial dural arteriovenous fistulas: classification, imaging findings, and treatment. Am J Neuroradiol 2012;33:1007Y13. doi:10.3174/ajnr.A2798. 4. Nishimura S, Hirai T, Sasao A, et al. Evaluation of dural arteriovenous fistulas with 4D contrast-enhanced MR angiography at 3T. Am J Neuroradiol 2010;31:80Y5. doi:10.3174/ajnr.A1898.
Otology & Neurotology, Vol. 36, No. 7, 2015
Copyright © 2015 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
