Caroticocavernous fistula
 

A patient with a right proptosis caused by caroticocavernous  fistula. Arterialization of the episcleral vessels caused by caroticocavernous fistula.

. Caroticocavernous fistula typically causes unilateral proptosis with a red eye. However, no all proptosed eye with redness  are caused by carotid cavernous fistula. The signs to look for in CCF are pulsation and arterialization of the episcleral  vessels. Otherwise, conditions like thyroid eye disease, pseudotumour and cavernous haemangioma can also give rise to  proptosis with engorged vessels (but no arterialization) There is unilateral proptosis with arterialization of the episcleral vessels. The globe is pulsating on close observation. Bruit can be hear over the orbit (best with the bell of the stethoscope). In severe cases, there may be ophthalmoplegia due to orbital  congestion. Mention you would like to examine: the intraocular pressure the anterior segment and posterior segment for signs of ischaemia (anterior uveitis, rubeosis iridis, cotton wool spots etc). .

Questions:

1. What are the different types of caroticocavernous fistula?

Answer
Direct fistula:
high flow and high pressure, where the defect is between the cavernous sinus and the intracavernous portion of the internal carotid artery. Bruit is common. Basal skull fracture is the commonest injury which gives rise to this type of fistula.

Indirect fistula:

low flow and low pressure where the defect is between the meningeal branches of the internal carotid artery and the cavernous sinus. It is often associated with hypertension and arteriosclerosis.

2. The following scan belongs to a patient who suffered from a right sided caroticocavernous fistula. What pathology can be seen here?
 

Answer The scan shows right proptosis with an  enlarged superior ophthalmic vein. This is a  sign of increased pressure in the cavernous  sinus and in this case caused by the  caroticocavernous fistula.

 
 

3. What are the treatment options for caroticocavernous fistula?

Answer
Some fistula may close spontaneously, especially the indirect type.
Treatment is difficult and usually reserved for patients with symptoms such as pain, exposure keratopathy, optic nerve damage and severe glaucoma.
Treatment include:
immobilization using balloon catheter7
ligation oft he ipsilateral carotid artery

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