Excerpt from Caroticocavernous Fistula

Synonyms, Key Words, and Related Terms: caroticocavernous fistula, cc fistula, dural arteriovenous fistula, arteriovenous shunting, type A caroticocavernous fistulas, type B caroticocavernous fistulas, type C caroticocavernous fistulas, type D caroticocavernous fistulas, intracavernous vessels, intracavernous arteries, intracavernous aneurysm, fibromuscular dysplasia, Ehlers-Danlos syndrome, collagen vascular diseases, atherosclerotic vascular disease, ophthalmic venous hypertension, orbital venous congestion, proptosis, chemosis, arterialization of episcleral veins, diplopia, visual loss, III cranial nerve palsy, IV cranial nerve palsy, V cranial nerve palsy, VI cranial nerve palsy, cranial nerve paralysis, central retinal vein occlusion, retinopathy, glaucoma, bruit, headache, visual loss, intracavernous internal carotid artery, cavernous sinus, dural shunt

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The caroticocavernous fistula is a specific type of dural arteriovenous fistula characterized by abnormal arteriovenous shunting within the cavernous sinus.

History of the Procedure

Case reports of dural arteriovenous fistulas were first published in the 1930s. The clinical presentation was recognized, but the pathophysiology was not well understood. During the 1970s and 1980s, the anatomy was further elucidated. Barrow and associates developed the current classification system of caroticocavernous fistulas in 1985.¹

Problem

A caroticocavernous fistula (see Image 3) results in high-pressure arterial blood entering the low-pressure venous cavernous sinus. This interferes with normal venous drainage patterns and compromises blood flow within the cavernous sinus and the orbit.

Frequency

Caroticocavernous fistulas represent approximately 12% of all dural arteriovenous fistulas. Type A is more common in young males. Types B, C, and D are more common in women older than 50 years, with a 7:1 female-to-male ratio.

Etiology

Caroticocavernous fistulas can be caused by trauma. Blunt and penetrating head injuries can result in a caroticocavernous fistula. They also can occur spontaneously. Most caroticocavernous fistulas are of spontaneous origin and unknown etiology.

Pathophysiology

Blunt head injury can lead to shearing of intracavernous arteries, causing the development of a fistula. Penetrating head injury can lead to fistula formation by direct laceration of intracavernous vessels.

Spontaneous fistula formation has been associated with (1) ruptured intracavernous aneurysm, (2) fibromuscular dysplasia,² (3) Ehlers-Danlos syndrome and other collagen vascular diseases, (4) atherosclerotic vascular disease, (5) pregnancy, and (6) straining.

Clinical

The onset is usually sudden.

Ocular manifestations (see Image 1) can include ophthalmic venous hypertension and orbital venous congestion, proptosis, corneal exposure, chemosis, and arterialization of episcleral veins. Other ocular manifestations may include diplopia, visual loss, cranial nerve palsy (III, IV, V, VI), central retinal vein occlusion, retinopathy, and glaucoma. Bruit and headache also may be present upon clinical presentation.

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