INTRACEREBRAL HEMORRHAGE / VASCULAR MALFORMATIONS

Carotid-cavernous fistula (CCF)

Created 21/04/2021, last revision 26/06/2023

  • 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 ICA or 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 Barrow C type CCF fed from ECA branches (DSA) 
    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
Ocular manifestations of CCF

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 Enlarged ophtalmic vein (orange arrow) and oculomotor muscles on the affected side 
    • in the case of trauma,  CT in the bone window should rule out skull base fracture
  • vascular imaging
    • CTA/MRA   Direct CCF (Type A) on MRA  Indirect carotid-cavernous fistula (CCF) type B on CT angiography. The red arrow shows early filling of the right cavernous sinus
      • ideal for initial diagnosis
      • normal results cannot exclude carotid-cavernous fistula; DSA should be performed if CCF is suspected
    • DSA  Barrow C type CCF fed from ECA branches (DSA)
      • the essential imaging modality
      • shows the size and location of the fistula, assesses its hemodynamic impact and venous drainage
  • ophthalmological examination   Cystoid macular edema and ischemic retinopathy in indirect CCF
    • 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 Endocrine orbitopathy on MRI
    • no significant chemosis, no increased filling of  vessels on the fundus
  • cavernous sinus thrombosis
  • retrobulbar orbital expansion
  • cluster headache

Management

  • endovascular (transarterial or transvenous) embolization techniques are the preferred treatment modality for the management of CCFs
  • tinnitus disappears immediately after a successful procedure
  • eye symptoms resolve gradually (within 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. 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)

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Carotid-cavernous fistula (CCF)
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