Carotid-cavernous sinus fistulas are abnormal communications between the carotid arterial system and the venous cavernous system. Although infantile presentations are rare, this entity in the differential diagnosis of proptosis and conjunctival injection can lead to significant vision loss if unrecognized. A unique case is presented and the diagnosis and management of carotid-cavernous fistulas are reviewed.
A 4-month-old male infant presented with acute onset of redness and proptosis of the left eye for 2 weeks. There were no associated neurological symptoms or behavioral changes suggesting the child was experiencing pain. There was no medical history, including connective tissue disease or head trauma. There was no family history of ocular disease. The infant was full term and delivered by uncomplicated vaginal delivery to a mother with gestational diabetes who was taking insulin.
On examination, Teller preferential visual acuity and intraocular pressures by Tono-Pen (Reichert Technologies, Depew, NY) were normal. Extraocular motility was full without nystagmus. The pupils were equal and normally reactive without a relative afferent pupillary defect. There was mild episcleral injection and 3 mm of relative proptosis of the left eye. Both corneas were clear and of normal diameter. The left optic disc appeared slightly hyperemic and retinal vessels were slightly tortuous and dilated. The right eye was unremarkable. Initial magnetic resonance imaging examination showed enhancing and enlarged medial and superior rectus muscles of the left orbit with involvement of the muscle tendons thought to be consistent with myositis. Complete blood count and thyroid function tests were normal. A working diagnosis of idiopathic orbital inflammation was made, and the infant was given oral prednisone 1 mg/kg/day.
Initial treatment resulted in mild decrease in episcleral injection, but repeat magnetic resonance imaging and magnetic resonance angiography showed an enlarged left superior ophthalmic vein and either a persistent dorsal ophthalmic artery or enlarged left inferolateral trunk arising from the cavernous left internal carotid artery (Figures 1–2). These findings were consistent with an indirect internal carotid-cavernous sinus fistula, although a formal angiogram would have more definitively defined the vascular anatomy. The parents refused catheter angiography and embolization therapy, opting instead for conservative management. At 11 months of age, the infant was taken on a 1-hour plane ride in hopes of inducing spontaneous closure of the fistula. At 21 months of age, the child continued to have 2 to 3 mm of proptosis and minimal episcleral injection of the left eye. Visual acuity and intraocular pressure remained normal in both eyes.
T1-weighted, gadolinium-enhanced magnetic resonance imaging, coronal view with fat suppression, demonstrating enlarged left superior ophthalmic vein (long arrow) and enlarged extraocular muscles (short arrows).
Magnetic resonance angiography of the brain, axial view, demonstrating an enlarged superior ophthalmic vein (larger arrow), suggestive of a left carotid cavernous fistula. The smaller arrow points to an enlarged left inferolateral trunk versus a persistent dorsal ophthalmic artery.
Carotid-cavernous sinus fistulas are abnormal vascular communications between the high-pressure carotid arterial system and the low-pressure venous cavernous system. Infantile carotid-cavernous sinus fistulas are rare but noteworthy because they may lead to amblyopia and permanent visual loss. However, the etiology of infantile carotid-cavernous sinus fistulas is unclear.1–3
Carotid-cavernous sinus fistulas are classified anatomically based on arterial origin. Direct fistulas involve the internal carotid artery and usually result from severe head trauma or ruptured cavernous aneurysms. Indirect fistulas result from communications with meningeal branches of either the internal or external carotid arteries. Indirect fistulas are generally lower-flow shunts with more insidious onset and milder ocular signs and symptoms. They usually occur in adult women or patients with connective tissue disease.
Carotid-cavernous sinus fistulas in infancy are especially rare, with six published reports to our knowledge. One case was a direct carotid-cavernous sinus fistula4 and 5 cases were indirect carotid-cavernous sinus fistulas.1–3,5,6 All cases of indirect congenital carotid-cavernous sinus fistulas involved branches of the external carotid artery, most commonly the middle meningeal artery. To our knowledge, indirect carotid-cavernous sinus fistula in infancy originating from the internal carotid artery has not been previously reported.
The ophthalmic manifestations of carotid-cavernous sinus fistulas arise from the interference of normal venous drainage and include dilated conjunctival vessels, proptosis, chemosis, orbital bruit, extraocular muscle palsy, elevated intraocular pressure, and decreased visual acuity. Indirect carotid-cavernous sinus fistulas in adults are less likely to lead to ophthalmoplegia and progressive visual loss than direct carotid-cavernous sinus fistulas. However, in pediatric cases the clinical signs of indirect carotid-cavernous sinus fistulas appear to be closer in severity to direct carotid-cavernous sinus fistulas.1
Initial work-up of suspected carotid-cavernous sinus fistula involves magnetic resonance imaging or computed tomography scanning, but all cases should be confirmed angiographically. Diagnostic angiography itself may often thrombose small fistulas and lead to resolution of symptoms. The primary indication for treatment is progressive visual loss or amblyopia. Visual deterioration may be secondary to decreased retinal perfusion, anterior segment ischemia, or intractable glaucoma.6 Substantial proptosis and extraocular muscle edema may also impede the normal development of ocular motility.6
The preferred method of treating infantile carotid-cavernous sinus fistulas is endovascular embolization. Five of the 6 reported cases of carotid-cavernous sinus fistula in infants were successfully treated by surgical interventions.1,2,4–6 Our report is the second case of conservative therapy for carotid-cavernous sinus fistula in infancy.3 Although high altitude is known to increase the risk of vascular thrombosis, no studies have examined air travel as a means to treat small fistulas. Although unsuccessful in our case, therapeutic hypobaric closure of carotid-cavernous sinus fistulas may be a subject of future investigations. Aggressive treatment of infantile carotid-cavernous sinus fistulas has been successful, but surgical intervention is not free of complications.1,4,6 Thus, as in our case, conservative management with close observation may be a viable option in infants with visually stable carotid-cavernous sinus fistula.
- Cohen JE, Gomori JM, Grigoriadis S, Rajz G. Endovascular treatment of congenital carotid-cavernous fistulas in infancy. Neurol Res. 2008;30:649–651. doi:10.1179/174313208X291612 [CrossRef]
- Konishi Y, Hieshima GB, Hara M, et al. Congenital fistula of the dural carotid-cavernous sinus: case report and review of the literature. Neurosurgery. 1990;27:120–126. doi:10.1227/00006123-199007000-00018 [CrossRef]
- Yamamoto T, Asai K, Lin YW, Yoshimo K, Yano K, Takeuchi K. Spontaneous resolution of symptoms in an infant with a congenital dural caroticocavernous fistula. Neuroradiology. 1995;37:247–249. doi:10.1007/BF01578267 [CrossRef]
- Rai AT, Sivak-Callcott JA, Larzo C, Marano GD. Direct carotid cavernous fistula in infancy: presentation and treatment. Am J Neuroradiol. 2004;25:1083–1085.
- Biglan AW, Pang D, Shuckett EP, Kerber C. External carotid-cavernous fistula in an infant. Am J Ophthalmol. 1981;91:351–356. doi:10.1016/0002-9394(81)90289-0 [CrossRef]
- Albayram S, Selcuk H, Ulus S, Selcuk D, Kocer N, Islak C. Endovascular treatment of a congenital dural caroticocavernous fistula. Pediatr Radiol. 2004;34:644–648. doi:10.1007/s00247-004-1163-2 [CrossRef]