Introduction
Background
Carotid-cavernous sinus fistula is an abnormal communication between the internal or external carotid arteries and the cavernous sinus. These lesions may be classified based on the following: etiology (traumatic vs spontaneous), velocity of blood flow (high vs low), and anatomy (direct vs dural, or internal carotid vs external carotid).
Pathophysiology
Carotid-cavernous sinus fistulae occur because of traumatic or spontaneous rents in the walls of the intracavernous internal carotid artery or its branches. This results in short-circuiting of the arterial blood into the venous system of the cavernous sinuses.
Direct carotid-cavernous sinus fistulae, which represent 70-90% of all carotid-cavernous sinus fistulae in most series, are characterized by a direct connection between the intracavernous segment of the internal carotid artery and the cavernous sinus. These fistulae usually have high rates of arterial blood flow and most commonly are caused by a single traumatic tear in the arterial wall.
Dural carotid-cavernous sinus fistulae are characterized by a communication between the cavernous sinus and one or more meningeal branches of the internal carotid artery, external carotid artery, or both. These fistulae usually have low rates of arterial blood flow and almost always produce symptoms and signs spontaneously, without any antecedent trauma or manipulation. The lesions may represent congenital arteriovenous malformations, which develop spontaneously or in association with atherosclerosis, systemic hypertension, collagen vascular disease, pregnancy, and during or after childbirth.
Frequency
United States
Rare
International
Rare
Mortality/Morbidity
Nearly all patients with a direct carotid-cavernous sinus fistula experience progressive ocular complications if the fistula is left untreated. Increasing proptosis, conjunctival chemosis, and visual loss occur over months to years, with central retinal vein occlusion and secondary glaucoma representing the most severe ocular complications.
Several investigators have reported severe epistaxis and intracerebral hemorrhage, potentially fatal, in patients with traumatic carotid-cavernous sinus fistulae. Subarachnoid hemorrhage also may complicate the course of a traumatic carotid-cavernous sinus fistula. A 3% incidence of spontaneous intracerebral hemorrhage caused by carotid-cavernous sinus fistulae has been reported.
Visual loss, although less frequent than in patients with direct carotid-cavernous sinus fistulae, occurs in 20-30% of patients with dural carotid-cavernous sinus fistulae and may be due to secondary ischemic optic neuropathy, chorioretinal dysfunction, including central retinal vein occlusion, or uncontrolled glaucoma.
Sex
- While direct carotid-cavernous sinus fistulae generally are associated with trauma or surgical manipulation, dural carotid-sinus fistulae occur more commonly in middle-aged to elderly women.
Age
- Traumatic carotid-cavernous sinus fistulae occur more commonly in young individuals.
- Dural carotid-cavernous sinus fistulae usually occur in middle-aged to elderly women but may produce symptoms at any age, including infancy.
Clinical
History
- Elicit history of trauma, recent childbirth, or surgical manipulation.
- Elicit history of atherosclerosis, systemic hypertension, collagen vascular disease, pseudoxanthoma elasticum, connective tissue diseases (eg, Ehlers-Danlos syndrome), or pregnancy.
- Patients may present with the following ocular complaints:
- Red eye
- Diplopia
- Bruit (buzzing or swishing sounds)
- Decreased vision
- Bulging eye
- Facial pain in the distribution of the first (and rarely the second) division of the trigeminal nerve
Physical
- Ophthalmologic examination findings consistent with carotid-cavernous sinus fistula include the following:
- Proptosis
- Eyelid edema
- Ocular pulsations (visible and/or palpable)
- Pulsating exophthalmos
- Ocular bruit
- Conjunctival arterialization and chemosis
- Exposure keratopathy
- Dilation of retinal veins
- Optic disc swelling
- Intraretinal hemorrhage
- Vitreous hemorrhage
- Proliferative retinopathy
- Central retinal vein occlusion
- Elevated intraocular pressure
- Neovascular glaucoma
- Angle-closure glaucoma (In rare cases, increased orbital venous pressure leads to iris and choroid congestion and forward displacement of the iris-lens diaphragm.)
Causes
- Approximately 25% of carotid-cavernous sinus fistulae occur spontaneously, especially in middle-aged to elderly women, and may be associated with atherosclerosis, systemic hypertension, collagen vascular disease, pregnancy, connective tissue disorders (eg, Ehlers-Danlos syndrome), and minor trauma.
- Cerebral trauma accounts for approximately 75% of carotid-cavernous sinus fistulae, with motor vehicle accidents, fights, and falls representing the most common settings. The injuries may be penetrating or nonpenetrating and may be associated with basal or facial skull fracture.
- Iatrogenic fistulae have been reported following trans-sphenoidal pituitary surgery, endarterectomy, ethmoidal sinus surgery, and percutaneous gasserian and retro-gasserian procedures.
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References
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Higginbotham EJ. Glaucoma associated with increased episcleral venous pressure. In: Albert DM, Jakobiec FA, eds. Principles and Practice of Ophthalmology. 2nd ed. 2000: 2781-92.
Ishijima K, Kashiwagi K, Nakano K, et al. Ocular manifestations and prognosis of secondary glaucoma in patients with carotid-cavernous fistula. Jpn J Ophthalmol. Nov-Dec 2003;47(6):603-8. [Medline].
Keltner JL, Satterfield D, Dublin AB, Lee BC. Dural and carotid cavernous sinus fistulas. Diagnosis, management, and complications. Ophthalmology. Dec 1987;94(12):1585-600. [Medline].
Kirsch M, Henkes H, Liebig T, et al. Endovascular management of dural carotid-cavernous sinus fistulas in 141 patients. Neuroradiology. Jul 2006;48(7):486-90. [Medline].
Miller NR. Carotid-cavernous sinus fistulas. In: Miller NR, ed. Walsh and Hoyt's Clinical Neuro-Ophthalmology. 4th ed. Baltimore, Md: Williams;1991: 2165-209.
Rai AT, Sivak-Callcott JA, Larzo C, Marano GD. Direct carotid cavernous fistula in infancy: presentation and treatment. AJNR Am J Neuroradiol. Jun-Jul 2004;25(6):1083-5. [Medline].
Troost BT, Glaser JS, Morris PP. Aneurysms, arteriovenous communications, and related vascular malformations. In: Glaser, ed. Neuro-ophthalmology. 3rd ed. Philadelphia, Pa: Lippincott Williams & Wilkins;1999: 589-628.
de Keizer R. Carotid-cavernous and orbital arteriovenous fistulas: ocular features, diagnostic and hemodynamic considerations in relation to visual impairment and morbidity. Orbit. Jun 2003;22(2):121-42. [Medline].
Further Reading
Keywords
carotid cavernous fistula, carotid-cavernous sinus fistula, carotid artery, cavernous sinus
