Carotid Cavernous Fistula

Carotid Cavernous Fistula
Presentation by: Laura S Gilmore, MD
Department of Ophthalmology, TTUHSC

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:
o rupture of intracavernous aneurysms
o neurofibromatosis
o atherosclerotic disease
o 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%
o 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
o Basal skull fracture tears ICA within cavernous sinus
o Traumatic fistulae-high flow rates, sudden and dramatic onset of symptoms
* Spontaneous rupture of aneurysm or atherosclerotic artery in 25%
o Post-menopausal, hypertensive females
o 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
o flow reversal leads to engorged ophthalmic veins causing proptosis, conjunctival injection, chemosis.
o Patients complain of retro-orbital headache, or a bruit. Facial pain with V1 and V2 involvement
* Other manifestations:
o congestion of the opposite orbit
o diplopia
o ptosis, mydriasis
o corneal ulceration
o loss of visual acuity
o transient neurological deficits
o subarachnoid hemorrhage

Radiological Evaluation of CCSF

* Angiography is the definitive diagnostic examination
* CT and MRI may show
o Enlarged superior ophthalmic vein
o Enlarged muscles
o Enlarged cavernous sinus with a convex shape to the lateral wall

Treatment of CCSF

* Most are not life-threatening
o Only involved eye is at risk typically
* Main indicators for treatment
o Glaucoma
o Diplopia
o Intolerable bruit or HA
o Severe proptosis causing exposure keratopathy
o 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
o Intravascular approach-placement of thrombogenic materials, eg coils
* Other therapies include:
o carotid artery ligation
o 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

Carotid Cavernous Fistula.ppt