Surgical Therapy
Various options are available for the management of CCFs depending on the flow rate. The goal is to achieve complete occlusion of the fistula while preserving normal ICA flow. In cases of indirect, low-flow fistulas, spontaneous closure is possible.
Endovascular intervention is the first-line treatment of CCFs. For direct, high-flow CCFs, the transarterial route is preferred. Surgical options include suturing or clipping the fistula, packing the cavernous sinus, or ligating the ICA. Radiosurgery is not an option for urgent cases, because it can take months to achieve complete obliteration. For low-flow fistulas, compression treatment is the least invasive option, consisting of compression a number of times a day for 4-6 weeks to achieve fistula thrombosis. [3]
In the acute setting of vision loss and/or paralysis of cranial nerves, glucocorticosteroids (eg, dexamethasone) may be used while waiting for definitive diagnostic studies and treatments. [17]
Type A fistulas rarely resolve spontaneously. Treatment is recommended for intolerable bruit, progressive visual loss, and the cosmetic effects of proptosis. [3]
Type A fistulas usually are approached through the internal carotid artery. A detachable balloon can then be positioned to occlude the fistula while maintaining patency of the internal carotid artery. Venous approaches through the internal jugular vein and the petrosal sinus may allow access to the fistula from the venous side. Guglielmi detachable coils also may be used and are becoming increasingly popular. [17]
Types B, C, and D fistulas have a higher incidence of spontaneous resolution. [3]
Type B, C, and D fistulas have smaller fistulous connections and usually are not amenable to the aforementioned treatment approaches. Carotid self-compression for 20-30 seconds 4 times per hour may lead to thrombosis of the fistula. Patients are instructed to compress the carotid artery on the side of the lesion using their contralateral hand. Should the patient develop cerebral ischemia during the compression, the contralateral hand likely will be affected, releasing the compression.
If compression is not effective or if a more rapid intervention is indicated, selective endovascular embolization of the fistula through the external carotid artery usually is effective. Several choices of embolic material are available, although polyvinyl alcohol usually is preferred.
Occasionally a fistula may require an endovascular approach through the superior ophthalmic vein. This requires surgical exposure of the vein to allow placement of the catheter.
Direct surgical exposure and obliteration of the fistula has been described. This rarely is indicated because endovascular approaches have been developed.
Severely refractory fistulas can be treated by surgical or endovascular sacrifice of the internal carotid artery. This, too, is rarely indicated.
In a study of 38 patients with dural carotid-cavernous fistulas, medical treatment was performed in 16% of patients, external ocular compression in 8%, transarterial embolization in 13%, transvenous embolization in 60%, and radiosurgery in 3%. Clinical cure was achieved in 58% of patients and improvement in 24%; anatomic cure was demonstrated in 68%; and transient worsening or new onset of ocular symptoms was observed in 29%. [17]
In a study of clinical and neuroradiologic results in 13 patients with carotid-cavernous fistulas treated by coiling of the cavernous sinus, there was complete occlusion of the fistula in 7 patients (7/13, 54%) and a resolution of symptoms in 8 patients (8/12, 67%). Coiling was performed with a semicompliant nondetachable balloon inflated in the internal carotid artery. The authors noted that balloon-assisted coiling permitted a clear visualization of the fistula, facilitated coil positioning, and protected the patency of the artery. [18]
Patients usually require a follow-up angiogram to ensure that the fistula has not recurred or that alternate fistulous pathways have not developed.
Complications of untreated lesions may include visual loss, cranial nerves paralysis, and the cosmetic concerns of proptosis. [3]
Patients with CCFs generally have a good prognosis. Persistent lesions respond well to intervention. The risk of nonophthalmologic neurologic complications is not significant; however, persistent untreated lesions may cause significant visual complications.
Complications of treatment include the standard complications of cerebral angiography. Arterial and venous compromise also may occur, yielding cerebral or retinal ischemia and resultant infarction. [17]
Medical Care
Exposure keratopathy may be treated with ocular lubricants, and, in severe cases, a tarsorrhaphy may be needed.
Glaucoma may require treatment with aqueous suppressants and hyperosmotic agents.
Laser peripheral iridectomy may be performed to eliminate the contribution of pupillary block, and cycloplegic agents may be used to encourage a posterior shift of the iris-lens diaphragm.
Laser iridoplasty or goniosynechialysis may help further in opening the angle.
Proliferative retinopathy and neovascular glaucoma may require panretinal photocoagulation.
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Type-D caroticocavernous fistula: the eye demonstrates proptosis, chemosis, and scleral edema. The patient is unable to close the eye, exposing the cornea to dehydration and potential trauma.
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Panel A is an angiogram of caroticocavernous fistula showing filling of the cavernous and circular sinuses. Panel B shows a post-Guglielmi detachable coil, ie, coiling of the fistula. The red arrow points to coils within the cavernous and circular sinuses after obliteration of the fistula.
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This is a diagrammatic representation of the 4 types of caroticocavernous fistulas. ICA is the internal carotid artery; ECA is the external carotid artery.
