Bilateral indirect carotid cavernous fistula

Case contributed by Siobhan Lee
Diagnosis certain

Presentation

Recurrent bilateral subconjunctival hemorrhage. Progressive right eye visual acuity loss, diplopia with ophthalmoparesis, red eye and exophalthmos.

Patient Data

Age: 70 years
Gender: Female

CT brain angiogram demonstrates abnormal early enhancement in both cavernous sinuses, similar to arterial enhancement in the internal carotid arteries and exceeding enhancement in the transverse sinuses. 

Enhancement extends into the superior and inferior ophthalmic veins bilaterally, which are mildly engorged. In the right superior ophthalmic vein, there is an abrupt cut-off of enhancement in the posterior orbit with the corresponding vessel being hyperdense on the non-contrast series, suggesting a thrombus.

Non-contrast CT brain is otherwise normal. No intracranial hemorrhage, retrobulbar fat stranding or enlargement of the extraocular muscles.

Cerebral angiogram

dsa

Cerebral catheter digital subtraction angiography demonstrates abnormal early arterial enhancement in each cavernous sinus on angiographic injection through the CCA and ECA, with absent enhancement on injection through the ICA bilaterally. This appearance confirms bilateral indirect carotid cavernous fistula, each side supplied by meningeal branches arising from both internal maxillary arteries. 

Each cavernous sinus drains anteriorly through the ophthalmic vein. There is right superior ophthalmic vein thrombosis. Normal vertebrobasilar system (not pictured).

Carotid cavernous fistula embolization was performed, with access via the right femoral vein. Both cavernous sinuses were accessed via the left facial vein. A microcatheter was advanced initially into the right cavernous sinus, which was embolized with coils until occlusion was achieved. The left was then subsequently embolized. Post procedure control runs confirmed complete exclusion of both carotid cavernous fistulas.

Case Discussion

This case demonstrated dural shunts arising bilaterally from meningeal branches of the ECA, in keeping with indirect carotid cavernous fistulas (Barrow type C). Indirect fistulas develop between branches of the carotid circulation and the cavernous sinus, rather than directly arising from the intracavernous ICA. As in this case, indirect fistulas most commonly involve meningeal branches from the ECA.

Indirect carotid cavernous fistulas are more likely to develop insidiously in postmenopausal females, as in this case. Recurrent subconjunctival hemorrhage over the preceding months, with several days of progressive visual loss and (non-pulsatile) exophthalmos prompted presentation to ED and investigation. Endovascular transvenous occlusion of the cavernous sinus was successful, with resolution of symptoms.

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