Carotid Cavernous Fistula

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Carotid Cavernous Fistula

• Laura S Gilmore, MD
• Department of Ophthalmology
• TTUHSC
• February 13, 2004
• Discussant Kenn Freedman, MD

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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

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Differential Diagnosis

• Cavernous Sinus Thrombosis
• Retrobulbar Hematoma
• Unrecognized intra-orbital FB, with possible
  cellulitis
• Carotid Cavernous Sinus Fistula
• Tumor

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Physical Exam

• General sedated, intubated
• Lids edematous, margins intact
• Pupils 2.5mm-gt2mm, 7-gtNR
• Conj chemosis, OSgtOD 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

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MRI of CC Fistula
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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

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Types of CC Fistula
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Mechanisms of CCSF

• Trauma
• Spontaneous causes
• rupture of intracavernous aneurysms
• neurofibromatosis
• atherosclerotic disease
• collagen vascular disease
• Iatrogenic

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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

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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

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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

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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

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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

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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

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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

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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

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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)

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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

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Summary

• Direct CCSF usually results from trauma
• Patients typically present with proptosis,
  conjunctival injection, and a bruit
• Angiography when pt stable
• Transarterial embolization