Clinical Features

The primary problem is a rise in the orbital venous pressure. Clinical findings of arteriovenous fistulas include dilation and tortuosity of the conjunctival and episcleral vessels, chemosis, ocular motility problems, proptosis, choroidal detachment,85 and secondary glaucoma.86 Secondary acute angle closure glaucoma has also been reported to occur with arteriovenous fistulas.87 Ocular motility problems can be twofold. Generalized ophthalmoplegia is probably due to congested swollen extraocular muscles.82 Isolated abduction weakness can also develop in patients with carotid cavernous fistula. The abduction weakness is due to sixth nerve palsy occurring either in the cavernous sinus or more posteriorly near the inferior petrosal sinus.82 Rarely,

FIGURE 14.14. (A) Facial photograph of a 54-year-old man with carotid cavernous fistula affecting the right eye demonstrates the proptosis of the right eye and conjunctival and episcleral injection. The right eye had secondary glaucoma unresponsive to topical drops. (B) Tl-weighted axial orbital MR image showing the dilated superior ophthalmic vein on the right side. (C) Tl-weighted contrast enhanced coronal orbital MR image showing the equally enlarged extraocular muscles on the right side. (D) Postoperative appearance of the patient 2 months after balloon catheterization and closure of the fistula.

FIGURE 14.15. Photographs of a 40-year-old man with dural cavernous fistula involving the left eye showing (A) proptosis and (B) conjunctival and episcleral injection. Inset: T1-weighted coronal orbital MR image depicting the enlarged extraocular muscles on the left side. (C) Cerebral angiogram demonstrating the arteriovenous communication between the meningeal branches of the external carotid artery and the cavernous sinus. (D) Appearance of the patient 2 months after transarterial catheterization and embolization of the fistula.

third or fourth nerve palsy can also be seen in patients with arteriovenous fistulas.82

The clinical and radiologic findings are more severe in carotid cavernous fistula than in dural cavernous and orbital arteriovenous fistulas (Figures 14.14 and 14.15).86 These findings typically occur ip-silateral to the carotid cavernous sinus but may also occur on the contralateral side owing to the presence of connections between the cavernous sinus on both sides.88 Anomalous intracranial venous drainage such as atresia of sinuses can also lead to a clinical picture similar to arteriovenous fistulas.89

Rarely, the anomalous arteriovenous vascular proliferations present within a mass lesion simulating an orbital tumor (Figure 14.16).90 Some patients experience a severe exacerbation of symptoms before undergoing clinical improvement. This has been correlated clinically with superior ophthalmic vein thrombosis.91 One report documented an occasion of uncontrolled bleeding at enucleation after penetrating orbital trauma, resulting from an unsuspected carotid cavernous fistula.92 These anomalous vascular aggregates may or may not have vascular feeder vessels. The presence or absence of a circulatory relationship should be investigated with angiography before surgery.

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