ccf

It is a abnormal communication between carotid arteries and cavernous sinus.

Classification:

They may be traumatic or spontaneous, high or low flow, direct or dural fistulae as determined by angiography.

Angiographic classification is widely followed and helps in the treatment planning.

Type A- is a direct shunt from the internal carotid to the cavernous sinus.
Type B- is between the branches of internal carotid and the sinus.
Type C- is between the branches of the external carotid and the sinus.
Type D- is between the branches of both internal and external carotids and the sinus; it is the commonest.

Etiology:

Traumatic fistulas are the commonest (75%) with a male preponderance. They are high flow fistula.

Severe closed head injury is the commonest cause. Penetrating injuries rarely cause the fistulas.

Post surgical (transphenoidal procedures, percutaneous Gasserian rhizotomy, intracranial carotid embolectomy) causes are

very rare.

Spontaneous fistulas are low flow ones and account for 20%, occurring in the older age group with a female preponderance.

Exact cause is not known. It may be congenital as in other AVMs or may be due to micro traumatic rupture of the meningeal

branches of the carotids.

Intracavernous carotid artery aneurismal rupture constitute a minor group (5%) and are more common in females, presenting

as spontaneous fistula. They may be high or low flow depending on size of rupture.

Pathology:

The cavernous sinus is distended along with the superior orbital vein and the sphenoparietal sinus leading onto intraorbital

swelling and hence proptosis which is down and out. Stasis contributes to chemosis, conjunctival edema and prolapse.

Reduced perfusion pressure in the ophthalmic artery and the increased intra-orbital and venous pressure leads to retinal

ischemia and blindness; there may be vitreous hemorrhage, papilledema and in chronic stage, glaucoma.

Severe proptosis may lead to corneal ulcerations and perforation of the globe.

Clinical features:

The symptoms and signs depend on the type, size and site (either anterior or posterior) of the fistula.

Type A are usually high flow and due to trauma or rupture of intracavernous carotid aneurysm. They do not close

spontaneously and require active treatment. Pulsating exophthalmus, chemosis, ocular nerve palsies causing diplopia, visual

loss and exposure keratitis are the usual manifestations. Facial pain due to involvement of cranial nerves V1 and V2 may be

there. Flow through cortical veins may produce raised ICT and headache.

A subjective and audible bruit may be present.

The ocular signs may be bilateral or contralateral due to the intercavernous communications.

A CCF is seldom fatal. Associated tear of the lateral intracranial dura can lead to subdural or subarchnoid haemorrhage.

In spite of extensive steal from the intracranial circulation, hemispheric signs are rare.

In type B, C, D, the symptoms are mild and of insidious onset; may be self remitting.

Investigations:

CT and MRI may suggest a distended cavernous sinus and rule out other causes of ocular manifestations. They may also help to study the extent of skull fracture, if any.

Angiography is the preferred imaging. Selective internal and external carotid studies will help.

Transcranial Doppler and SPECT scanning help in assessing tolerance in carotid occlusion.

Type A CCF- angio (Lat)

Management:

The indication for active intervention is the progressive visual loss. Types B, C, D are low flow and reported to close spontaneously in 16 to 60%. Angiography alone may promote spontaneous closure, it has been reported. Protection of the eye during the waiting period is advised.

Active intervention is indicated in progressive symptoms. The aim is to occlude the fistula without occluding the internal carotid either by embolization or surgery.

Type A can be closed by embolization either intraarterial through the internal carotid or intravenous through the superior ophthalmic vein or the superior or inferior petrosal sinus through surgical exposure; direct surgery may be required in the failed cases.

Type B is rare and requires direct surgery usually.

Type C is also rare and can be embolized.

Type D is the commonest; External carotid feeders may be embolized and internal carotid feeders may require surgery.

Surgery may involve ligation of the carotid (CCA or ICA) in the neck, trapping of the cavernous segment of the carotid, both proximally and distally or direct exposure of the lesion and micro reconstruction of the involved segment which is a surgical challenge.