Aunt Mickey (They Look the Same until You Undress Them). Carotid-Cavernous Fistula or Something Else?

A middle age woman presented with left progressive proptosis.  A contrast enhanced CT was done and showed enlargement of the left superior ophthalmic vein on the axial plane (see below).  A coronal image confirmed this abnormality and demonstrated that the extraocular muscles and retro-orbital fat had a normal appearance.

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Physical examination showed no chemosis, vision loss or cranial nerve palsies.  Because of this the patient was brought back for repeat contrast enhanced CT of the orbits with Valsalva maneuver.  This study showed mild additional enlargement of the already prominent left superior ophthalmic vein and also of the right sided one (see below).  The combination of imaging and clinical findings was thought to be most compatible with orbital varices.  The patient opted for conservative management.

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Orbital varices are hamartomas composed of slow flow, low pressure and thinned walled and distensible blood vessels.  As they communicate with the rest of the circulation, they enlarge with Valsava, bending or prone position, and coughing and straining.  They produce proptosis which may be painful and because they may bleed, their symptoms may become acutely exacerbated.  They may also erode adjacent bone.  Treatment is very difficult and is reserved for those with repeated hemorrhages, thrombosis, optic nerve compression and disfigurement.  Orbital vascular processes included in the differential diagnosis are carotid cavernous fistulas of both types and less likely, venous thrombosis.

In CC fistulas, the ipsilateral cavernous sinus may be enlarged particularly in the direct ones (see below).  Extra-ocular muscles may also be large and the retro-ocular fat may have a “dirty” appearance.  In most patients with direct CCFs, chemosis, decreased vision and cranial nerve palsies are present.  Acute thrombosis of the superior ophthalmic vein may present with symptoms that are similar to those of a direct CCF.  Indirect CCFs may have less acute symptoms and be clinically similar to varices.  The diagnosis is confirmed with catheter angiography as shown here.

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Suggested readings:

YO Arat, ME Mawad, M Boniuk. Orbital Venous Malformations: Current Multidisciplinary Treatment Approach. Arch Ophthalmol 2004; 122: 1151 – 1158

N Islam, K Mireskandari, GE Rose. Orbital varices and orbital wall defects. Br J Ophthalmol 2004; 88: 1092 – 1093

A Weill, C Cognard, L Castaings, G Robert, J Moret. Embolization of an orbital varix after surgical exposure. AJNR Am. J. Neuroradiol. 1998; 19: 921 – 923

Aunt Mickey (They Look the Same until You Undress Them). Carotid-Cavernous Fistula or Something Else?
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Mauricio Castillo • Univ of North Carolina

I am Division Chief of Neuroradiology at the University of North Carolina in Chapel Hill. In addition, I am a Professor of Radiology and the current Editor-in-Chief of the American Journal of Neuroradiology. I trained in Diagnostic Radiology at the University of Miami and was a Neuroradiology fellow at Emory University.