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A 54 year old woman with a red eye
Digital Journal of Ophthalmology 2004
Volume 10, Number 8
July 28, 2004
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 Chris Hammond | Princess Royal Hospital Gurmit Uppal | St Thomas Hospital Saurabh Jain | St Thomas Hospital
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| Diagnosis and Discussion | Arteriovenous shunts involving the cavernous sinus are rarely congenital. Some 25% occur spontaneously especially in middle aged women secondary to atherosclerosis while cerebral trauma accounts for the rest 75%, usually in the young. Hemodynamically they may be divided into high-flow and low flow, which is usually determined by the severity of clinical findings.
The fistula is usually initiated by a rent in the wall of the intracavernous internal carotid artery or its branches with short-circuiting of arterial blood into the venous complex of the cavernous sinus. This leads to raised venous pressure and reduced arterial perfusion with soft tissue swelling and anterior segment ischemia.
Fistulae may be asymptomatic or have a range of presentations including lid swelling, orbital pain, pulsating exophthalmos of varying degrees, subjective or ocular or cephalic bruit, diplopia, engorged conjunctiva and raised IOP. The fundal changes include dilated veins, disc edema, retinal hemorrhages, venous stasis retinopathy or even venous occlusions (1).
Enlarged extra ocular muscles are visible by ultrasonography as is reverse flow of blood in the superior ophthalmic vein (2). An aid to definitive diagnosis is complete angiographic evaluation with selective opacification of bilateral internal and external carotid arteries and vertebral circulation. Prominence of the superior ophthalmic vein is frequently detected on CT scan and MRI may help visualize lateral bulging of the cavernous sinus (3,4).
Therapy is directed towards relieving ocular symptoms and preserving vision. Many fistulae close spontaneously and do not require anything beyond intervention. However, sight threatening fistulae need more agressive treatment with the goal being thrombosis of the fistula with normalization of orbital hemodynamics. The preferred method of treatment is intravascular closure of the fistula, which may be achieved by detachable balloon micro catheterization techniques or embolization with Isobutyl –2-cyanoacrylate or polyvinyl alcohol particles
Another method of transvenous embolization utilizes Guglielmi detachable coils and fibered platinum coils. Various routes have been tried including inferior petrosal sinus (IPS) alone, IPS and inter-cavernous sinus, IPS and clival plexus, superior ophthalmic vein (SOV) via facial vein and SOV via superficial temporal vein (5).
Transvenous embolization through retrograde catheterization of the superior ophthalmic vein can allow complete coil occlusion of the lesion with marked improvements in visual outcome (6).
This case illustrates the spectrum of subtle to conspicuous ocular manifestations that can be seen in patients with CCF and its potential to present as an emergency. CCF should be included in the differential diagnosis of an "atypical" red eye. Recognition of arterialised conjunctival vessels and auscultation of an orbital bruit raises the possibility of a CCF, requiring prompt diagnostic studies (7).
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