Carotid Cavernous Fistula

Laura S Gilmore, MDDepartment of Ophthalmology

TTUHSCFebruary 13, 2004

Discussant: Kenn Freedman, MD

Case Presentation

• 26yo AAM s/p MVA • CHI, L zygoma fracture• Consulted for proptotic, red OS• CT: proptosis OS. No basilar skull

fracture. no retrobulbar hematoma, no superior ophthalmic vein enlargement, no ocular muscle enlargement

Differential Diagnosis

Cavernous Sinus Thrombosis• Retrobulbar Hematoma• Unrecognized intra-orbital FB, with

possible cellulitis• Carotid Cavernous Sinus Fistula• Tumor

Physical Exam

• General: sedated, intubated• Lids: edematous, margins intact• Pupils: 2.5mm->2mm, 7->NR• Conj: chemosis, OS>OD; SCH OS• IOP: 16, 28• Cornea 2+ edema OS, clear OD• + gross proptosis OS• + bruit OS on auscultation, no neck bruit• DFE: discs flat with sharp edges, vessels

normal, retina flat OU

MRI of CC Fistula

Carotid Cavernous Fistula

• Abnormal communication between previously normal carotid artery and cavernous sinus

• Characterized as:-Direct vs. Indirect-High vs. Low Flow-Traumatic vs. Spontaneous

Types of CC Fistula

Mechanisms of CCSF

• Trauma• Spontaneous causes:

– rupture of intracavernous aneurysms– neurofibromatosis– atherosclerotic disease– collagen vascular disease

• Iatrogenic

Direct Carotid Cavernous Fistula

• Arterial blood passes directly through a defect in the wall of intracavernous portion of ICA

• Blood in vein becomes arterialized• Venous pressure increases• Arterial pressure and perfusion

decreases

Signs of Direct CCSF• Ptosis• Very red, chemotic conj• Increased IOP from increased

episcleral venous pressure• Anterior segment ischemia in 20%

– Corneal edema, cell/flare, iris atrophy, rubeosis, cataract

• Proptosis is pulsatile• Bruit and thrill• Muscle palsies• Visual loss

Etiologies of Direct CCSF• From trauma in 75% of all cases

– Basal skull fracture tears ICA within cavernous sinus

– Traumatic fistulae-high flow rates, sudden and dramatic onset of symptoms

• Spontaneous rupture of aneurysm or atherosclerotic artery in 25%– Post-menopausal, hypertensive females– Lower flow rates, less severe symptoms

Mechanisms of Traumatic CCSF

• direct injury from basilar skull fracture

• injury from torsion or stretching of the carotid siphon upon impact

• impingement of the vessel on bony prominences

Indirect Carotid Cavernous Fistula

• Fistulous connection is within the wall of the cavernous sinus

• Tend to be low-flow• Small meningeal arteries supplying dural

wall of cavernous sinus can rupture spontaneously, while ICA itself remains intact

• Insidious onset, mild orbital congestion, proptosis, low or no bruit

• Lesions may fluctuate, and may resolve spontaneously

Clinical Presentation of CCSF• Ophthalmic consequences of CCSF are

caused by compression and ischemia related to increased venous pressure and reduced arterial pressure– flow reversal leads to engorged

ophthalmic veins causing proptosis, conjunctival injection, chemosis.

– Patients complain of retro-orbital headache, or a bruit. Facial pain with V1 and V2 involvement

Clinical Presentation of CCSF

• Other manifestations:– congestion of the opposite orbit– diplopia– ptosis, mydriasis– corneal ulceration– loss of visual acuity– transient neurological deficits– subarachnoid hemorrhage

Radiological Evaluation of CCSF

• Angiography is the definitive diagnostic examination

• CT and MRI may show– Enlarged superior ophthalmic vein– Enlarged muscles– Enlarged cavernous sinus with a

convex shape to the lateral wall

Treatment of CCSF• Most are not life-threatening

– Only involved eye is at risk typically• Main indicators for treatment

– Glaucoma– Diplopia– Intolerable bruit or HA– Severe proptosis causing exposure

keratopathy– Spontaneous closure from thrombosis

of cavernous sinus is unlikely (as in trauma, high-flow)

Treatment of CCS Fistulas

• 99% of treatment is done by interventional neuroradiologists– Intravascular approach-placement of

thrombogenic materials, eg coils

• Other therapies include:– carotid artery ligation– surgical exposure with clipping of the

fistula

Summary

• Direct CCSF usually results from trauma

• Patients typically present with proptosis, conjunctival injection, and a bruit

• Angiography when pt stable• Transarterial embolization