Carotid cavernous fistulas are a type of dural arteriovenous fistula that involves the cavernous sinus. There are two types of carotid cavernous fistula (CCF):
- Direct carotid-cavernous fistula
- Indirect carotid-cavernous fistula
Classification (by catheter angiography):
- Barrow Type A i.e. direct CCF: direct ICA to Cavernous sinus shunt. i.e. no dural arterial branches are involved
- Type B: dural ICA branches to cavernous sinus shunt
- Type C: dural ECA (meningeal feeding via external carotid) to cavernous shunt
- Type D: ECA/ICA dural branches to cavernous sinus
Direct carotid-cavernous fistula (direct CCF):
Diagnosis:
Clinical:
- Days or weeks post trauma or post rupture of cavernous ICA aneurysm
- Cavernous sinus syndrome w pulsatile exophthalmos
- Ischemic and hemorrhagic complications
Catheter angiography DSA:
- Arterial supply: Rapid direct filling of cavernous sinus from ICA, on ICA injection. Uncommonly, ECA feeders (internal maxillary artery, APhA)
- Venous drainage via: ophthalmic veins (superior and inferior). +/-Other drainange: contralateral cavernous sinus, petrosal sinuses (superior & inferior), ponto-mesenscephalic veins, basal vein of Rosenthal, middle cerebral veins (deep & superficial).
- If severe ICA laceration, no distal ICA flow
- Examine both ICA, ECA and VA injections
CTA:
- Opacification of cavernous sinuses
MRI:
- Dilated superior ophthalmic vein or other draining veins
- Cerebral edema in some cases with extensive venous hypertension
Treatment, Type A, (direct CCF):
It is important to get a baseling neuro-ophthalmological examination and to measure intraocular pressure
Endovascular treatment:
- Arterial approach via Internal carotid artery
- Venous approach via jugular vein and inferior petrosal sinus, or via facial vein or superior ophthalmic vein
- Embolization agents:
- Detachable balloons
- Balloon assisted coil embolization
Indirect carotid-cavernous fistula (indirect CCF):
Diagnosis:
Clinical:
- Gradual onset of carotid cavernous syndrome: ophthalmoplegia, conjunctival injection, raised intraocular pressure, proptosis
- Cavernous sinus syndrome with pulsatile exophthalmos
- Ischemic and hemorrhagic complications
Catheter angiography DSA:
- Arterial supply: Dural arterial branches (from external carotid artery or from dural branches of the internal carotid artery)
- Fistula point: within the cavernous sinus
- Venous drainage: any of the outlet drainage of the cavernous sinus; the superior ophthalmic vein, the pterygoid plexus, the inferior petrosal sinus, the bridgeing veins to the brainstem etc.
- Typical arterial feeders:
- Distal IMA, APhA, MMA, cavernous ICA branches (uni- or bi-lateral)
- Rarely only ECA or ICA branches
- Typical venous drainage:
- Variable: one or both of the patterns below:
- Superior & inferior ophthalmic veins if anterior fistula
- Inferior petrosal sinus & superior petrosal sinus if posterior fistula
- Typical pial vein involvement:
- Usually none
- directly to Superficial & deep middle cerebral veins, or via paracavernous sinus via connection with pterygoid plexus
- to bridging vein to ponto-mesencephalic vein to peduncular vein to Basal vein of Rosenthal
- to Superior petrosal sinus to petrosal vein to lateral mesencephalic vein to basal vein of Rosenthal
- to petrosal vein to cerebellar veins
CTA:
- Opacification of cavernous sinuses
MRI:
- Dilated superior ophthalmic vein or other draining veins
- Cerebral edema in some cases with extensive venous hypertension
Treatment indirect CCF:
It is important to get a baseling neuroophthalmological examination and to measure intraocular pressure
Type B, C, D (indirect CCF)
- Consider Carotid-jugular compression for diagnosis if not contraindicated
- or Endovascular treatment
Endovascular treatment:
- Venous approach via jugular vein and inferior petrosal sinus, or via facial vein or superior ophthalmic vein
- Arterial approach via dural branches of the external carotid artery or dural branches of the internal carotid artery
- Embolization agents:
- Detachable balloons
- Balloon assisted coil embolization