Disorders Nerve Cranial• 7 SECTIONMotor Ocular Multiple

Indirect (Dural) Carotid–cavernous Fistula

Key Facts

•Abnormal connection between pericavernous dural arterial branches and cavernous venous plexus

•Arises from opening of pre-existing shunt vessels, usually in postpartum or postmenopausal women

•Congestive orbital and ocular features much less florid than in direct carotid– cavernous fistula

•Patient may report hearing pulse-synchronous bruit but not as frequently as with direct carotid–cavernous fistula

•Clinical features may disappear spontaneously as fistula closes or blood is rerouted

•Endovascular treatment is indicated only for:

•refractory pain

•diplopia

•optic neuropathy

•vision-threatening elevation in IOP

•unsightly congestion

Clinical Findings

•Periocular pain, eyelid swelling, proptosis

•Arterialized corkscrew conjunctival injection

•Diplopia, reduced ocular ductions

•Optic nerve dysfunction

•Elevated IOP

•Retinal vein engorgement, perivenous hemorrhages

•Pulse-synchronous bruit (whooshing sound)

Ancillary Testing

•MRI or perhaps CT usually shows dilated superior ophthalmic vein and enlargement of extraocular muscles, but fistula may not be evident except on source images

•Selective dye injection of external carotid artery often shows multiple dilated feeder vessels and premature appearance of dye in cavernous sinus

Differential Diagnosis

•Graves disease

•Orbital myositis

•Orbital tumor

•Chronic conjunctivitis

A

B

Fig. 7.8 (A) Preoperative photograph of a patient with an indirect (dural) carotid–cavernous fistula shows lid and conjunctival edema with engorged conjunctival vessels. (B) After closure of the fistula (see Fig 7.9), congestive features have disappeared.

Fistula cavernous–Carotid (Dural) Indirect

Disorders Nerve Cranial• 7 SECTIONMotor Ocular Multiple

Indirect (Dural) Carotid–cavernous Fistula (Continued)

Treatment

•Observe for spontaneous closure for several months unless patient has refractory pain, uncontrollably high IOP, or vision-threatening optic neuropathy

•For IOP >30, use pressure-lowering agents

•Attempt endovascular closure only if spontaneous improvement has not occurred for several months and patient has refractory pain, diplopia, optic neuropathy, vision-threatening elevation in IOP, or unsightly congestion

Prognosis

•Spontaneous closure of fistula occurs in about 50%

•Indirect fistulas may be difficult to close if there are multiple feeders; several procedures may be required but risks are generally tolerable

Fig. 7.9 Lateral views of cerebral angiogram of patient in Fig. 7.8. (A) Pretreatment common carotid

angiogram shows early dye filling of the cavernous sinus (arrow) and superior ophthalmic vein (arrowhead).

(B) Pretreatment selective external carotid angiogram shows tiny arterial feeders of the fistula (black arrows) and early filling of the cavernous sinus (white arrows). (C) Post-treatment common carotid angiogram shows that

A the cavernous sinus no longer fills with dye because the sinus has been filled with coils (arrows).

B

C

(continued) Fistula cavernous–Carotid (Dural) Indirect