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Figure 1. This preoperative composite photograph shows the patient’s extraocular movements with notable right sided ptosis and limited abduction, as well as proptosis of the right eye.
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Figure 2. A preoperative computed tomography (CT) scan highlights a dilated superior ophthalmic vein in the right orbit.
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Figure 3. A 2-month postoperative composite photograph shows the extraocular movements with improvement in abduction and ptosis of the right eye.
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Figure 4. A postoperative computed tomography (CT) scan redemonstrates the superior ophthalmic vein, but with marked reduction in engorgement.
A 35-year-old woman with no significant medical or ocular history suffered trauma to the head after being involved in a motorcycle accident. The patient underwent a 10-day stay at an intensive care unit (ICU) in an outside hospital for treatment of hemorrhagic brain injuries along with posterior skull fractures. One month after discharge, she presented to the ophthalmology clinic for evaluation of headaches, diplopia, ptosis and “bulging” of the right eye.
Initial examination revealed a visual acuity of 20/30 (right eye) and 20/40 (left eye). Ophthalmic examination was significant for right-sided ptosis, proptosis, and elevated intraocular pressure (IOP) of 30 mm Hg OD. Testing of extraocular movements demonstrated limitation of abduction (-4), supraduction (-1), and infraduction (-1) of the right eye (Figure 1). No optic disc pallor or blurring was present and there was no relative afferent pupillary defect. Color vision was full in both eyes, and the patient denied pulsatile tinnitus or transient visual obscurations.
The left eye examination was unremarkable. CT angiography of the head exhibited marked right ophthalmic vein distension in addition to multiple right orbital wall fractures (Figure 2).
This patient’s history of trauma, imaging, and presenting physical exam findings (unilateral diplopia, proptosis, ptosis, and elevated IOP) are consistent with a diagnosis of carotid cavernous fistula (CCF). Carotid cavernous fistulas are abnormal vascular shunts between either the internal carotid...
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This patient’s history of trauma, imaging, and presenting physical exam findings (unilateral diplopia, proptosis, ptosis, and elevated IOP) are consistent with a diagnosis of carotid cavernous fistula (CCF).
Carotid cavernous fistulas are abnormal vascular shunts between either the internal carotid artery or external carotid artery and the cavernous sinus. The relatively high-flow arterial blood flow enters the low-flow venous system of the cavernous sinus, leading to elevation in blood pressure of the venous system. This elevation in pressure causes engorgement of the venous system as well as mass effect on the structures passing through the cavernous sinus, namely cranial nerves VI, V1, V2, IV, and III.
Carotid cavernous fistulas can be categorized by either flow velocity (high flow vs low flow), drainage (anteriorly draining vs posteriorly draining), or by Barrow classification (A, B, C, D). Barrow classification includes: Type A (direct high flow shunt between the internal carotid artery and the cavernous sinus), Type B (between dural branches of the internal carotid artery and the cavernous sinus), Type C (between the dural branches of the external carotid artery and cavernous sinus), Type D (between dural branches of both the internal and external carotid arteries and cavernous sinus).1
Our patient’s presentation is typical of a direct, high-flow carotid cavernous fistulas (Barrow Type A). These high flow CCFs commonly present with pulsatile exophthalmos, chemosis, and an ocular bruit known as Dandy’s Triad.1 As a result of the mass effect on the structures within the cavernous sinus, other findings include cranial nerve palsies, headaches, diplopia, visual disturbances, orbital pain, and dilated or engorged “corkscrew” conjunctival vessels.2 By contrast, indirect or low-flow carotid cavernous fistulas may be less obvious and more difficult to diagnose as they may appear in a relapsing remitting fashion and development of symptoms may occur slowly over time.
Trauma accounts for the etiology of 70-75% of all CCFs, most of which are high-flow and direct fistulas. Examples include acceleration-deceleration head injuries, skull fractures, iatrogenic injury, slash injuries, and missile injuries3. The remaining 30% are spontaneous in etiology, and are more prevalent in middle-aged to elderly females or those predisposed to vascular compromise such as patients with Ehlers-Danlos syndrome.3
The gold standard for diagnosis of a CCF is cerebral angiogram. However, computed tomography (CT), CT angiography, magnetic resonance imaging (MRI), and magnetic resonance angiography (MRA) are all valid and sensitive imaging modalities that may be used to highlight structures comprising the carotid cavernous fistula.4 Other tests that may provide supporting evidence of CCF include tonometry to measure elevated intraocular pressure, and a Hertel exophthalmometer to measure proptosis. Additionally, transorbital or transcranial Doppler imaging may prove useful to highlight orbital congestion, abnormal blood flow, or dilated ophthalmic veins.5
Treatment of ophthalmic complications include the use of topical or oral IOP- lowering medications for elevated IOP. Ultimately, closure of the carotid cavernous fistula is the definitive treatment. Treatment options to close CCFs vary and are dependent on the type of CCF. Fortunately, indirect, low flow fistulas exhibit spontaneous closure in 20-60% of cases4. For carotid cavernous fistulas requiring intervention, however, the current first-line treatment is endovascular embolization via coiling or through liquid embolization. For high flow, direct CCFs, endovascular coiling via a trans-arterial approach is the most commonly pursued option. For indirect CCFs, a transvenous route is the most advantageous.3
More invasive options may include surgical interventions, such as suture closure of the fistula, packing of the cavernous sinus, and clipping of the fistula.5 Stereotactic radiosurgery is only an option for low-flow carotid cavernous fistulas. One noninvasive therapeutic option is intermittent manual self-compression of the internal carotid artery, which aims to create thrombosis of the fistula.6
Prognosis is generally favorable; however, it is ultimately dependent on the success of the carotid cavernous fistula’s closure, as well as the time and extent of damage sustained during the pre-intervention period. Endovascular embolization results in a high success rate, with some reports as high as 80%.7 If successful closure is achieved, orbital bruits typically resolve immediately, while chemosis, raised IOP, and proptosis may resolve within days to weeks.4 Cranial nerve involvement and ocular misalignment generally improves within weeks to months, with notable improvements typically within 3 months.2
This case was contributed by Anthony S. Wong, an ophthalmology resident at John H. Stroger Jr., Hospital Of Cook County
The case was edited by Grayson W. Armstrong, MD, MPH, an instructor of ophthalmology at Massachusetts Eye and Ear and Harvard Medical School and Director of Ophthalmology Emergency Service.
References
1. Barrow DL, Spector RH, Braun IF, Landman JA, Tindall SC, Tindall GT. Classification and treatment of spontaneous carotid-cavernous sinus fistulas. J Neurosurg. 1985;62(2):248-56. doi:10.3171/jns.1985.62.2.0248
2. Williams ZR. Carotid-cavernous fistulae: a review of clinical presentation, therapeutic options, and visual prognosis. Int Ophthalmol Clin. 2018;58(2):271-294. doi:10.1097/IIO.0000000000000215
3. Henderson AD, Miller NR. Carotid-cavernous fistula: current concepts in aetiology, investigation, and management. Eye (Lond). 2018;32(2):164-172. doi:10.1038/eye.2017.240
4. Ellis JA, Goldstein H, Connolly ES Jr, Meyers PM. Carotid-cavernous fistulas. Neurosurg Focus. 2012;32(5):E9. doi:10.3171/2012.2.FOCUS1223
5. Miller NR. Dural carotid-cavernous fistulas: epidemiology, clinical presentation, and management. Neurosurg Clin N Am. 2012;23(1):179-92. doi:10.1016/j.nec.2011.09.008
6. Kai Y, Hamada J, Morioka M, Yano S, Kuratsu J. Treatment of cavernous sinus dural arteriovenous fistulae by external manual carotid compression. Neurosurgery. 2007;60(2):253-7;discussion 257-8. doi:10.1227/01.NEU.0000249274.49192.3B
7. Gemmete JJ, Ansari SA, Gandhi DM. Endovascular techniques for treatment of carotid-cavernous fistula. J Neuroophthalmol. 2009;29(1):62-71. doi:10.1097/WNO.0b013e3181989fc0
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