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Carotid-Cavernous Fistula Imaging

  • Author: Robert A Koenigsberg, MSc, DO, FAOCR; Chief Editor: James G Smirniotopoulos, MD  more...
 
Updated: Oct 28, 2015
 

Overview

Carotid-cavernous fistulas (CCFs) are abnormal communications between the carotid arterial system and the venous cavernous sinus. Most often, CCFs are broadly classified as either direct or indirect, on the basis of anatomic features depicted on angiograms. (See the images below.)

Carotid-cavernous fistula. Anatomic features are s Carotid-cavernous fistula. Anatomic features are shown: internal carotid artery (red) and cavernous sinus (purple).
Patient with a gunshot wound to the face in whom a Patient with a gunshot wound to the face in whom a left traumatic carotid-cavernous fistula developed. The case was further complicated with bilateral optic nerve injuries and a skull base fracture affecting the sphenoid bone and temporal bones bilaterally.
An almost complete carotid-cavernous fistula demon An almost complete carotid-cavernous fistula demonstrates only minimal runoff to the ipsilateral intracavernous carotid artery territory. Because runoff has occurred, carotid preservation remains the treatment of choice. In patients in whom absolutely no runoff is demonstrated, carotid sacrifice at the level of the carotid-cavernous fistula can be considered, if necessary, to close the fistula. Needless to say, this treatment also depends on the collateral vessels and the patient's ability to tolerate intracavernous carotid artery sacrifice.
Anteroposterior view of an almost complete carotid Anteroposterior view of an almost complete carotid-cavernous fistula demonstrates only minimal runoff to the ipsilateral intracavernous carotid artery territory. Because runoff has occurred, carotid preservation remains the treatment of choice. In patients in whom absolutely no runoff is demonstrated, consideration can be given to carotid sacrifice at the level of the carotid-cavernous fistula if necessary to close the fistula. Needless to say, this treatment also depends on the collateral vessels and the patient's ability to tolerate intracavernous carotid artery sacrifice.
CT image of the head at the level of the cavernous CT image of the head at the level of the cavernous sinuses demonstrating left cavernous sinus widening secondary to an underlying carotid-cavernous fistula.

Further classification is based on their etiologic and hemodynamic qualities. Clinical manifestations of CCFs frequently involve ophthalmologic abnormalities; many patients initially consult an ophthalmologist.[1]

Symptomatic direct CCFs (type A) spontaneously resolve only in rare cases. Therefore, they almost always require urgent treatment. The goal of treatment is to eliminate flow through the fistula but also to maintain internal carotid patency.[2, 3, 4]

Radiologic techniques are used in embolization of carotid-cavernous fistulas (CCFs). Angiography is invaluable for the guidance of catheter placement and delivery of the embolization materials. Angiography, computed tomography (CT) scanning, magnetic resonance imaging (MRI), and magnetic resonance angiography (MRA) are also useful in assessing the effectiveness of treatment.[5, 6, 7, 8] (See the image below.)

Direct carotid-cavernous fistula after embolizatio Direct carotid-cavernous fistula after embolization. The cavernous sinus is no longer filling with contrast material. Note the distinct borders of the intracavernous carotid artery.

Preferred examination

CT and MRI are the preferred radiologic modalities. Compared with angiography, CT and MRI have a much lower incidence of complications. Furthermore, CT and MRI scans depict peripheral pathologies associated with CCFs (eg, enlargement of cavernous sinus and the ophthalmic vein). Angiography is used to confirm CT or MRI findings prior to treatment.[9, 5, 10]

CT findings may be sufficient for diagnosis in most patients; however, MRI and angiography are superior in evaluating venous distension, the aneurysm lumen, and the increased flow to cavernous sinus.

Indirect signs associated with CCFs are not readily seen on angiographic images. MRIs and CT scans are limited because precise filling of the cavernous sinus and other signs of abnormal blood flow are not readily seen.

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Radiography

Plain radiographic findings are most useful for follow-up after embolization therapy, to evaluate balloon positioning or possible leakage.

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Computed Tomography

CT scan findings in carotid-cavernous fistulas include the following[11] :

  • Enlargement of the ipsilateral cavernous sinus (see the image below)
  • Enlargement and tortuosity of the superior ophthalmic vein
  • Enlargement of the extraocular muscles
  • Proptosis
    CT image of the head at the level of the cavernous CT image of the head at the level of the cavernous sinuses demonstrating left cavernous sinus widening secondary to an underlying carotid-cavernous fistula.

If the superior ophthalmic vein appears to be either asymmetric or larger than 4 mm in diameter, a carotid-cavernous fistula is suggested. CT scans do not depict a CCF if it is too small or has recently formed.

Regarding false-positive findings, the superior ophthalmic vein may be enlarged in patients with other orbital pathologies, eg, cavernous angioma of the orbit, or in patients with other vascular malformations with orbital venous drainage. In particular, other dural malformations of the head and neck can be associated with unusual orbital venous drainage.

Regarding false-negative findings, CCFs do not always drain into the superior ophthalmic vein. Therefore, the absence of this sign does not exclude the possibility of an underlying CCF.

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Magnetic Resonance Imaging

MRI findings in carotid-cavernous fistulas include the following[12, 13, 7, 8] :

  • Findings similar to those at CT
  • Abnormal flow voids in the affected cavernous sinus (see the image below)
  • Decreased MRI signal in the involved cavernous sinus
  • Dilated intercavernous sinuses and intercavernous vessels
  • Lateral wall convexity of the cavernous sinus
  • Dilated superior ophthalmic vein, ipsilateral or contralateral
  • Orbital edema
    Abnormal flow void in the left cavernous sinus reg Abnormal flow void in the left cavernous sinus region is demonstrated in a patient with an underlying carotid-cavernous fistula.

The role of MRI is limited by the ability to visualize dural CCFs; however, when it is used in conjunction with contrast-enhanced CT scanning, better diagnostic capability is achieved.

Regarding false-positive findings, MRI results are similar to CT findings in that the superior ophthalmic vein may be enlarged in patients with other orbital pathologies (eg, cavernous angioma of the orbit) or in patients with other vascular malformations with orbital venous drainage. In particular, other dural malformations of the head and neck can be associated with unusual orbital venous drainage resulting in enlargement of the orbital veins.

Regarding false-negative findings, MRI results are similar to CT findings in that CCFs do not always drain into the superior ophthalmic vein. Therefore, the absence of enlargement or lack of a prominent flow void does not exclude the possibility of an underlying CCF.

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Ultrasonography

Orbital sonograms demonstrate signs similar to those on CT scans and MRIs. In addition, orbital sonogram may demonstrate a reversal of flow direction in the superior ophthalmic vein.

Dilated tortuous veins may be prominent on B-scan echograms. With the A-scan method, dilated ophthalmic veins may be evident.[14] The scans may also demonstrate evidence of arterialized blood coursing through the ophthalmic veins, which are seen as several low-amplitude spikes that are in constant motion. A-scan ultrasonography also can show thickening of the optic nerve.

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Nuclear Imaging

Radionuclide cerebral angiography performed with technetium-99m pertechnetate shows increased uptake of the tracer in the area of the carotid siphons, with rapid clearance. This study is useful in the early postoperative period in a patient with a large CCF repair when angiography may be dangerous.

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Angiography

To accurately identify a carotid-cavernous fistula, selective catheterization of the right and left external and internal carotid arteries and the vertebral arteries is necessary. Including the entire skull in lateral projection imaging is important.

The angiographic appearance of a CCF can be variable and depends on the flow velocity of the blood and the anatomy of the affected arteries and veins. (See the images below.)[6]

Typical carotid-cavernous fistula. Lateral project Typical carotid-cavernous fistula. Lateral projection subtraction angiogram demonstrates characteristic filling of the internal carotid artery with the cavernous sinus secondary to a tear in the intracavernous carotid artery. Filling of both the superior (arrowhead) and inferior (arrow) ophthalmic veins is present. Courtesy of Gerard Debrun, MD.
Anteroposterior projection demonstrates a carotid- Anteroposterior projection demonstrates a carotid-cavernous fistula, with opacification of the cavernous sinuses seen bilaterally. Courtesy of Gerard Debrun, MD.
Carotid-cavernous fistula in a patient after ballo Carotid-cavernous fistula in a patient after balloon embolization with fistula closure.
Digital subtraction angiogram demonstrates a carot Digital subtraction angiogram demonstrates a carotid-cavernous fistula that arose secondary to spontaneous rupture of an underlying cavernous carotid aneurysm into the cavernous sinus. Note that the venous drainage extends to the right. The patient's complaints were related to right ocular ecchymosis.
Digital subtraction angiogram showing cortical ven Digital subtraction angiogram showing cortical venous drainage pathways over the right convexity to the superior sagittal sinus in a patient with a carotid-cavernous fistula.

On an intracavernous carotid arteriogram in a patient with direct CCF, arteriovenous shunting into the cavernous sinus is evident.

Immediate filling of the petrosal sinus and/or the ophthalmic vein is commonly evident when the intracavernous carotid artery is injected. Frame rates of greater than 5 frames per second and intracavernous carotid arterial injection rates of greater than 7 mL/s may aid in evaluating the morphology of high-flow fistulas.

The Mehringer-Hieshima maneuver may also be useful in improving delineation of the lesion. This maneuver involves a 2- to 3-mL/s injection into the ipsilateral intracavernous carotid artery with manual compression of the artery below the catheter tip in the neck. This compression allows flow control within the artery to aid in demonstrating the location of the tear.

The Huber maneuver involves an injection of the ipsilateral vertebral artery, with lateral-projection angiography performed by using manual compression of the affected carotid artery during the injection (see the image below). The retrograde siphon filling of the cavernous sinus is evident. The maneuver helps in identifying the upper extent of the fistula, and it can further help in demonstrating double-hole traumatic fistulas and complete cavernous-intracavernous carotid artery transection.

Huber maneuver demonstrates filling of the carotid Huber maneuver demonstrates filling of the carotid-cavernous fistula resulting from retrograde intracavernous carotid artery flow into the fistula.

The degree of confidence is high. Angiography unequivocally demonstrates the presence or absence of a CCF.

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Contributor Information and Disclosures
Author

Robert A Koenigsberg, MSc, DO, FAOCR Professor, Director of Neuroradiology, Program Director, Diagnostic Radiology and Neuroradiology Training Programs, Department of Radiology, Hahnemann University Hospital, Drexel University College of Medicine

Robert A Koenigsberg, MSc, DO, FAOCR is a member of the following medical societies: American Osteopathic Association, American Society of Neuroradiology, Radiological Society of North America, Society of NeuroInterventional Surgery

Disclosure: Nothing to disclose.

Specialty Editor Board

Bernard D Coombs, MB, ChB, PhD Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand

Disclosure: Nothing to disclose.

C Douglas Phillips, MD, FACR Director of Head and Neck Imaging, Division of Neuroradiology, New York-Presbyterian Hospital; Professor of Radiology, Weill Cornell Medical College

C Douglas Phillips, MD, FACR is a member of the following medical societies: American College of Radiology, American Medical Association, American Society of Head and Neck Radiology, American Society of Neuroradiology, Association of University Radiologists, Radiological Society of North America

Disclosure: Nothing to disclose.

Chief Editor

James G Smirniotopoulos, MD Professor of Radiology, Neurology, and Biomedical Informatics, Program Director, Diagnostic Imaging Program, Center for Neuroscience and Regenerative Medicine (CNRM), Uniformed Services University of the Health Sciences

James G Smirniotopoulos, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, American Society of Head and Neck Radiology, American Society of Neuroradiology, Association of University Radiologists, Radiological Society of North America, American Society of Pediatric Neuroradiology

Disclosure: Nothing to disclose.

Additional Contributors

Pamela W Schaefer, MD Associate Professor in Radiology, Harvard Medical School; Associate Director of Neuroradiology, Clinical Director of MRI and Director of Neuroradiology Fellowship Program, Massachusetts General Hospital

Disclosure: Nothing to disclose.

Acknowledgements

Vu Do, MD Staff Physician, Department of Radiology, Milton S Hershey Medical Center

Disclosure: Nothing to disclose.

Jeffrey Rykken, MMS Drexel University College of Medicine

Disclosure: Nothing to disclose.

References
  1. Oishi A, Miyamoto K, Yoshimura N. Etiology of carotid cavernous fistula in Japanese. Jpn J Ophthalmol. 2009 Jan-Feb. 53(1):40-3. [Medline].

  2. Jung JY, Kim SH, Kim DJ, Kim DI. Navigation-assisted transsphenoidal deflation of a detachable balloon in the cavernous sinus after embolization of a direct carotid-cavernous fistula. Acta Neurochir (Wien). 2007 Feb. 149(2):207-12; discussion 212. [Medline].

  3. Li MH, Tan HQ, Fang C, Zhu YQ, Wang W, Wang J, et al. Trans-arterial embolisation therapy of dural carotid-cavernous fistulae using low concentration n-butyl-cyanoacrylate. Acta Neurochir (Wien). 2008 Nov. 150(11):1149-56; discussion 1156. [Medline].

  4. Luo CB, Teng MM, Chang FC, Chang CY. Traumatic indirect carotid cavernous fistulas: angioarchitectures and results of transarterial embolization by liquid adhesives in 11 patients. Surg Neurol. 2009 Feb. 71(2):216-22. [Medline].

  5. Koc O, Genc E, Ozturk B, Genc BO, Keskin F, Ozbek O. Dural carotico-cavernous fistula: pre and postembolization appearances of bone-subtracted CT angiography. Turk Neurosurg. 2013. 23(2):249-51. [Medline].

  6. Chi CT, Nguyen D, Duc VT, Chau HH, Son VT. Direct traumatic carotid cavernous fistula: angiographic classification and treatment strategies. Study of 172 cases. Interv Neuroradiol. 2014 Jul-Aug. 20 (4):461-75. [Medline].

  7. Seeger A, Kramer U, Bischof F, Schuettauf F, Ebner F, Danz S, et al. Feasibility of Noninvasive Diagnosis and Treatment Planning in a Case Series with Carotid-Cavernous Fistula using High-Resolution Time-Resolved MR-Angiography with Stochastic Trajectories (TWIST) and Extended Parallel Acquisition Technique (ePAT 6) at 3 T. Clin Neuroradiol. 2015 Sep. 25 (3):241-7. [Medline].

  8. Harsha KJ, Basti RS, Kesavadas C, Thomas B. Susceptibility-weighted imaging in carotido-cavernous fistulas. A case control study. Interv Neuroradiol. 2013 Dec. 19 (4):438-44. [Medline].

  9. Gean AD. Imaging of Head Trauma. New York, NY: Raven Press. 1994: 349-54, 474.

  10. Korkmazer B, Kocak B, Tureci E, Islak C, Kocer N, Kizilkilic O. Endovascular treatment of carotid cavernous sinus fistula: A systematic review. World J Radiol. 2013 Apr 28. 5(4):143-55. [Medline]. [Full Text].

  11. Uchino A, Hasuo K, Matsumoto S, Masuda K. MRI of dural carotid-cavernous fistulas. Comparisons with postcontrast CT. Clin Imaging. 1992 Oct-Dec. 16(4):263-8. [Medline].

  12. Elster AD, Chen MY, Richardson DN, Yeatts PR. Dilated intercavernous sinuses: an MR sign of carotid-cavernous and carotid-dural fistulas. AJNR Am J Neuroradiol. 1991 Jul-Aug. 12(4):641-5. [Medline].

  13. Uehara T, Tabuchi M, Kawaguchi T, Mori E. Spontaneous dural carotid cavernous sinus fistula presenting isolated ophthalmoplegia: evaluation with MR angiography. Neurology. 1998 Mar. 50(3):814-6. [Medline].

  14. Spector RH. Echographic diagnosis of dural carotid-cavernous sinus fistulas. Am J Ophthalmol. 1991 Jan 15. 111(1):77-83. [Medline].

  15. Wetzel SG, Bilecen D, Lyrer P, et al. Cerebral dural arteriovenous fistulas: detection by dynamic MR projection angiography. AJR Am J Roentgenol. 2000 May. 174(5):1293-5. [Medline]. [Full Text].

 
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Carotid-cavernous fistula. Anatomic features are shown: internal carotid artery (red) and cavernous sinus (purple).
Typical carotid-cavernous fistula. Lateral projection subtraction angiogram demonstrates characteristic filling of the internal carotid artery with the cavernous sinus secondary to a tear in the intracavernous carotid artery. Filling of both the superior (arrowhead) and inferior (arrow) ophthalmic veins is present. Courtesy of Gerard Debrun, MD.
Anteroposterior projection demonstrates a carotid-cavernous fistula, with opacification of the cavernous sinuses seen bilaterally. Courtesy of Gerard Debrun, MD.
Carotid-cavernous fistula in a patient after balloon embolization with fistula closure.
Patient with a gunshot wound to the face in whom a left traumatic carotid-cavernous fistula developed. The case was further complicated with bilateral optic nerve injuries and a skull base fracture affecting the sphenoid bone and temporal bones bilaterally.
An almost complete carotid-cavernous fistula demonstrates only minimal runoff to the ipsilateral intracavernous carotid artery territory. Because runoff has occurred, carotid preservation remains the treatment of choice. In patients in whom absolutely no runoff is demonstrated, carotid sacrifice at the level of the carotid-cavernous fistula can be considered, if necessary, to close the fistula. Needless to say, this treatment also depends on the collateral vessels and the patient's ability to tolerate intracavernous carotid artery sacrifice.
Anteroposterior view of an almost complete carotid-cavernous fistula demonstrates only minimal runoff to the ipsilateral intracavernous carotid artery territory. Because runoff has occurred, carotid preservation remains the treatment of choice. In patients in whom absolutely no runoff is demonstrated, consideration can be given to carotid sacrifice at the level of the carotid-cavernous fistula if necessary to close the fistula. Needless to say, this treatment also depends on the collateral vessels and the patient's ability to tolerate intracavernous carotid artery sacrifice.
Huber maneuver demonstrates filling of the carotid-cavernous fistula resulting from retrograde intracavernous carotid artery flow into the fistula.
Direct carotid-cavernous fistula after embolization. The cavernous sinus is no longer filling with contrast material. Note the distinct borders of the intracavernous carotid artery.
CT image of the head at the level of the cavernous sinuses demonstrating left cavernous sinus widening secondary to an underlying carotid-cavernous fistula.
Abnormal flow void in the left cavernous sinus region is demonstrated in a patient with an underlying carotid-cavernous fistula.
Digital subtraction angiogram demonstrates a carotid-cavernous fistula that arose secondary to spontaneous rupture of an underlying cavernous carotid aneurysm into the cavernous sinus. Note that the venous drainage extends to the right. The patient's complaints were related to right ocular ecchymosis.
Digital subtraction angiogram showing cortical venous drainage pathways over the right convexity to the superior sagittal sinus in a patient with a carotid-cavernous fistula.
 
 
 
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