What is a Carotid-Cavernous Fistula (CCF)?

A Carotid Cavernous Fistula (CCF) is an abnormal vascular connection between the carotid arterial system and the cavernous sinus, a venous structure located at the base of the brain. CCFs can be classified as direct or indirect. Direct CCFs involve a direct connection between the internal carotid artery (ICA) and the cavernous sinus, often resulting from trauma or aneurysmal rupture. Indirect CCFs involve smaller branches of the carotid artery, and are usually idiopathic or due to conditions that increase venous pressure.

INTRACEREBRAL HEMORRHAGE / VASCULAR MALFORMATIONS

Carotid cavernous fistula (CCF)

David Goldemund M.D.
Updated on 11/03/2024, published on 01/02/2024

carotid cavernous fistula is a specific variant of arteriovenous fistula (→ DAVF) – it is defined as a pathological communication between the cavernous sinus (CS) and the internal carotid artery (ICA) or its branches (from either the ICA or the ECA or both)
CCF can occur spontaneously or as a result of trauma
the cavernous sinus is a venous plexus that receives drainage from the sphenoparietal sinus, superior ophthalmic vein (SOV), inferior ophthalmic vein (IOV), superior petrosal sinus (SPS), inferior petrosal sinus (IPS), and basilar venous plexus → anatomy of cerebral veins and dural sinuses

Classification

the Barrow classification is the most widely used system to categorize CCFs
type A is usually of traumatic etiology with the classic triad of clinical symptoms (tinnitus, pulsatile exophthalmos, and conjunctival chemosis)
indirect CCFs (C-D) are usually of spontaneous origin with milder clinical presentation

Etiology traumatic (75%) spontaneous (intracavernous aneurysm, vasculopathies such as Ehlers-Danlos or FMD)
Hemodynamic classification high-flow low-flow
Anatomy (type A-D) – the Barrow classification direct (type A) Type A – direct communication between ICA and cavernous sinus (CS) indirect, dural (type B-D) Type B – fistula is fed by ICA branches Type C – fistula is fed by ECA branches Type D – fistula is fed by both ICA and ECA branches

CCF classification according to Barrow (type A-D)

Clinical presentation

These symptoms are usually fully expressed in type A, whereas the findings are more subtle in indirect types (often only retrobulbar pain, diffuse headache, or conjunctival hyperemia)

pulsatile or persistent exophthalmos (proptosis)
- ipsilateral (up to 75%)
- bilateral (up to 1/3 of cases)
- contralateral to CCF
pulsatile tinnitus (mostly synchronous with the heartbeat) + murmur audible in the forehead, synchronous with a heartbeat and disappearing after compression of the carotid artery
painful ophthalmoparesis with diplopia (symptoms may fluctuate) [Li, 2019]
ipsilateral amaurosis
ipsilateral or bilateral conjunctival chemosis
dilated subcutaneous periorbital veins
papilledema
hemorrhagic complications (2%) – SAH, ICH, epistaxis

Diagnostic evaluation

brain CT/MRI
- CT/MRI does not show the fistula itself
- helps rule out other orbital or intracranial expansive lesions
- it may show enlargement of the cavernous sinus, ophthalmic veins, and oculomotor muscles
- in the case of trauma, CT in the bone window should rule out skull base fracture
vascular imaging
- CTA/MRA
  - ideal for initial diagnosis
  - normal results do not 100% exclude carotid-cavernous fistula; DSA should be performed if CCF is suspected
- DSA
  - the essential imaging modality
  - shows the size and location of the fistula, assesses its hemodynamic impact and venous drainage
ophthalmologic examination
- visual assessment
- fundoscopy – detection of vascular changes (dilated veins with potential hemorrhage) and papilledema

Direct carotid-cavernous fistula (CCF) type A on CT angiography

Differential diagnosis

tumors compressing the cavernous sinus (e.g., pituitary adenomas, craniopharyngiomas)
endocrine orbitopathies
- without significant chemosis and increased fundus vascular filling
cavernous sinus thrombosis
retrobulbar orbital expansive process
cluster headache

Management

endovascular embolization techniques (either transarterial or transvenous) are the preferred
tinnitus typically disappears immediately following a successful procedure
eye symptoms resolve gradually over weeks to months

Direct fistula (type A)

Endovascular treatment

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Neurosurgery

open surgery or radiosurgery are used as second-line or adjuvant therapeutic options, typically after the prior failure of endovascular procedures

Indirect fistula (type B-D)

it is recommended to monitor the patient with low-flow fistulas and mild symptoms, as the spontaneous resolution of symptoms due to fistula thrombosis is not uncommon
the effect of repeated external carotid compression under ultrasound guidance has been reported [Higashida, 1986] [Goldemund, 2006)
endovascular treatment is suggested in more severe cases and those with clinical progression (visual deterioration, malignant exophthalmos, and chemosis)
- coiling of the feeding artery
- transvenous cavernous sinus coiling

Embolization of feeding artery (CCF Barrow type C)