Medical and nonsurgical
Endovascular embolization is now the treatment of choice, replacing open surgical approach (Neurosurg Focus 2012; 32:E9).
Low-flow or dural cavernous fistulas have a high rate of spontaneous resolution and can at first be observed (Am J Neuroradiol 1991; 12:435).
Intervention is recommended for progressive, severe ocular symptoms.
Spontaneous resolution and thrombosis of the fistula has been reported after airplane travel, angiography (Am J Neuroradiol 1991; 12:435).
Manual compression of the external carotid artery and the angular vein can be prescribed for mild congestion.
- Patients are also instructed to compress the superomedial orbit for 5-10 minutes three times a day (Eur Radiol 2014; 24:3051).
Secondary effects of fistula formation can also be managed medically.
- Corneal exposure: Tarsorrhaphy and topical lubrication
- Elevated IOP: topical and systemic medication
- Diplopia: Occlusion and prisms followed by muscle surgery when disease is stabilized.
Initially, transcavernous surgical approach was developed after recognition and description of carotid cavernous fistula by Parkinson (J Neurosurg 1967; 26:420).
Kupersmith et al. reported successful transfemoral venous embolization in 33 of 34 patients in 1986 (Ophthalmology 1986; 93:906).
Keltner et al. followed with reported success with embolization in 71% of 18 patients with direct and indirect fistulas (Ophthalmology 1987; 94:1585).
General anesthesia is usually needed for embolization.
Transfemoral venous catheterization targets the inferior petrous sinus to gain access to the cavernous sinus.
Arterial catheterization — in contrast to transvenous catheterization — via femoral artery or external carotid artery is ideally avoided because it carries higher risk of traumatizing dural feeding arterioles off the internal carotid artery.
Transorbital approach via the superior ophthalmic vein offers more direct access to the cavernous sinus.
- The transorbital approach is generally performed under general anesthesia (Ophthalmology 2006; 113:1220).
- The superior ophthalmic vein enters the anterior orbital fat just lateral to the trochlea, as confluent drainage from the supraorbital and angular veins.
- The vein continues posteriorly, medial to the superior rectus muscle, close to the orbital roof.
- The superior ophthalmic vein crosses over to the lateral border of the superior rectus before entering the cavernous sinus via the annulus and Zinn and superior orbital fissure.
- Fat is reflected laterally to expose the vein which is isolated on a suture ligature.
- Recent onset high flow direct fistulas are not optimally approached directly via the orbit, to avoid excessive bleeding (Ophthalmology 2006; 113:1220).
- In a series of 91 dural indirect, low flow fistulas treated from 1993-2005, cannulation of the superior ophthalmic vein was attempted in 25 patients, with six unsuccessful attempts due to difficulties isolating and accessing the vein in the orbit (Ophthalmology 2006; 113:1220).
The internal carotid artery can be directly accessed via the orbit, in extreme cases (J Neurointervent Surg 2013; 5:e1).
The cavernous sinus can also be accessed via the inferior ophthalmic vein (J Neuroradiol 2012; 39:181).
Transfacial vein embolization via the internal jugular vein is an alternative approach for fistulas with anterior drainage (World Neurosurg 2015; 84:90).
- The facial vein can also be accessed by submandibular puncture (Neuro-Chirurgie 2014; 60:165).
- The facial vein, if tortuous, can be directly accessed by cutdown (J Clin Neuroscien 2014; 21:1238).
Options for fistula occlusion include platinum coils, fibrin glue, sclerosing agents, ethylene vinyl alcohol (onyx), bone wax, oxidized cellulose, stents, detachable balloons, and cyanoacrylate glue.
- Latex balloons filled with contrast material deflate within several weeks, sufficient time for closure of the fistula.
- Polymerizing agents in the latex balloon or other expansile materials risk compression of the 3rd, 5th,and 6th cranial nerves in the cavernous sinus and progressive neuropathy (Am J Neuroradiol 1991; 12:435).
If endovascular treatment fails, can revert to craniotomy (World Neurosurg 2012; 77:512).
Indications for treatment
- Obstruction of cortical venous drainage
- Progressive optic neuropathy
- Intractable ophthalmoplegia
- Intractable chemosis/exposure keratopathy