carotid cavernous fistulas ( ccf ) are uncommon disorders characterized by abnormal communications between the internal carotid artery ( ica ) and the cavernous sinus ( cs ) . divided ccf in four categories , with direct communications between ica - cs characterizing type a. types b , c and d are indirect dural shunts , having low blood flow . direct and indirect fistulas have different pathogenesis , with the last arising from meningeal arteries of the external and/or ica . direct connections have a high flow through the ica wall and are posttraumatic in 75% of cases . other etiologies include cavernous ica aneurysm rupture , arterial dissection , connective tissue disorders , iatrogenic causes and fibromuscular dysplasia . the mixing of venous and arterial blood leads to a venous hypertension transmitted to the orbital content . fremitus , chemosis , ocular nerve palsy , increased intraocular pressure ( iop ) and retinal hemorrhages may also occur , with all manifestations usually being ipsilateral to the fistula . we report a case of a patient with traumatic unilateral direct fistula and bilateral ocular presentation . ten months after a head trauma due to a road accident , a 38-year - old man presented frontal headache , low visual acuity ( va ) , increased volume and progressive conjunctival hyperemia in both eyes , with recent worsening . ectoscopy showed no pulsatile proptosis , ophthalmoparesis and bilateral chemosis were worse in the left eye ( fig . tonometry was 27 mm hg in the right eye and 28 mm hg in the left eye . extensive bleeding , major venous ectasia and bilateral papilledema were seeing in the fundoscopy and fluorescein angiography ( fa ) ( fig . ct scan with contrast showed proptosis , diffuse thickening of the extra - ocular muscles and bilateral dilatation of the ophthalmic veins . ophthalmic treatment with hypotensive eye drops and acetazolamide orally decreased levels of iop to 18 - 20 mm hg . cerebral digital subtraction angiography ( dsa ) showed right high - flow ccf , barrow type a , venous hypertension contralateral filling of cs ( fig . endovascular treatment was then performed positioning detachable balloons and coils into the right cs , interrupting the arteriovenous communication . immediate postoperative control dsa confirmed total occlusion of the fistula with patency of the ica ( fig . postoperatively , the patient had progressive decreasing of chemosis and proptosis , with discharged 48 h after presenting a right va of 20/80 and a left va of 20/100 and iop of 12/12 mm hg , without hypotensive eye drops or acetazolamide . ten day after the procedure , fa revealed mild right papilledema and rare bilateral microhemorrhages . the cs is a lateral sellar compartment , converging several sources of venous blood and crossed by the ica the widest connection in most of the cases is with the basilar plexus , present in 100% of the cases . other communications vary in size ; the anterior and posterior inter - cs are always present , whereas inferior inter - cs sinus is present in 97% of the cases . direct fistula typically begins by an ica wall bursting into the cs , usually producing lesions less prone to natural closure than indirect fistulas due to high flow . the ipsilateral eye is the most affected organ , ranging from mild episcleral expansion to exuberant clinical picture , with secondary glaucoma , severe proptosis and retinal hemorrhages   as in this case . although bilateral traumatic ccf may occur in 1 - 2% , unilateral ccf with ipsilateral symptomatology is far more common . unilateral fistulas with bilateral symptoms are rare because despite communications between the cs , there is a major decompressive route through the ophthalmic veins . contralateral venous ectasia requires wider communication between cs , possibly associated with a specific defect in the artery wall directing the inflow to the intercavernous sinus . diagnostic imaging of ccf include ct , mr , ctangio and mrangio , which can show asymmetric cs widening , orbital vein and extra - ocular muscles enlargement . whereas a completely normal exam does not exclude ccf , high clinical suspicion should follow dsa , the gold standard for the diagnosis and classification . dsa besides identifies location , size of the fistula and venous reflux , likewise allowing immediate treatment . ideally , the treatment should be performed when the lesion is diagnosed , and prompt treatment of high flow fistulas is recommended . even if most of the ccf is not life threatening , venous reflux causing intracranial hemorrhage or massive epistaxis can be fatal . angiographic image of dilated cs with extension into the subarachnoid space and pseudoaneurysm was associated with fatal hemorrhage by halbach et al . . increased intracranial pressure , proptosis with untreatable corneal exposure , visual deterioration , hemorrhage and transient ischemic attacks require emergent or aggressive intervention . treatment indications may either include diplopia , intolerable headache or bruit , secondary glaucoma and anterior segment ischemia . the management of ocular symptoms may help , but the definitive treatment is focused on reducing venous pressure . earlier , the surgical technique was based on carotid ligation , depending on the existence of collateral blood flow to maintain cerebral perfusion , later evolving to endovascular deployment of the detachable balloon . several approaches have been described : arterial , transfemoral transvenous , puncture of superior orbital vein and combined . the endovascular approach preserving the ica is currently the treatment of choice for these lesions and can be performed positioning detachable balloons into the cs through the fistula . in addition , coils deployment is a frequently used technique and can be associated with either stents or flow diverters to avoid coil herniation . balloon deployment reduced the flow but failed to totally occlude the fistula , requiring the use of detachable coils . the clinical improvement mainly depends on the evolution time until fistula resolution , with timely intervention avoiding irreversible neuropathies . immediate treatment as in this case allows better results , with early hospital discharge and complete patient recovery . the authors report no conflicts of interest concerning the materials or methods used in this study or the findings specified in this paper .
unilateral carotid cavernous fistula presents with ipsilateral ocular findings . 
 bilateral presentation is only seen in bilateral fistulas , usually associated with indirect ( dural ) carotid cavernous fistulas . 
 direct carotid cavernous fistulas are an abnormal communication between the internal carotid artery and the cavernous sinus . 
 they typically begin with a traumatic disruption in the artery wall into the cavernous sinus , presenting with a classic triad of unilateral pulsatile exophthalmos , cranial bruit and episcleral venous engorgement . 
 we report the case of a 38-year - old male with traumatic right carotid cavernous sinus fistula and bilateral ocular presentation successfully treated by interventional neuroradiology .