Carotid cavernous fistula (CCF) is an abnormal communication between the cavernous sinus and the carotid arterial system. The indirect fistula develops because of a leak from the weakened artery due to some pre existing pathology. The onset is gradual with mild symptoms, hence a high level of suspicion is needed for their diagnosis which is facilitated by various imaging techniques like CT scan, MRI, Doppler, ultrasonographv, MRA, and angiography1. Spontaneous resolution of these fistulas have been reported2 hence they are managed conservatively. Weighing the risks, angiography is performed only when active intervention is planned. Ophthalmologist may be the first physician to encounter a patient with clinical manifestations of CCF and this article stresses the need to keep this differential diagnosis in mind to minimise mortality and morbidity.
A 53 year old lady presented with, the complaint of headache for the last 03 months. The headache was moderately severe, throbbing in nature and aggravated by stooping. Initially she had nausea of right eye but it settled down after few weeks. The patients also noticed redness of right eye with mild protrusion for the last one month. There was no complaint of vomiting, diplopia or neck stiffness. She had dry cough for the last five months with out any fever dyspenea or weight loss. There was no history of trauma conjuctival itching, discharge, or sticking of eyelids.
Her general physical examination revealed an afebrile middle-aged lady with a pulse of 88/min blood pressure of 120/80 mmHg, and respiratory rate of 14/min, Examination of chest, heart, abdomen and nervous system reveald no abnormality.
Ophthalmic examination revealed vision of 6/6 in both eyes. Extra ocular movements were equal and full on both sides. Right globe showed mild axial proptosis measuring 21 mm compared to 199mm on left side, bruit and pulsation were absent and proptosis did not change by any change of posture of valsalva maneuver. Anterior segment revealed faint conjunctival hyperemia with dilated and tortuous vessels and deep anterior chamber. Fundus examination, also showed mild venous dilatation. Intraocular pressure measured; by Goldman applanation tonometer was 32 & 20 mmHg on right and left side respectively. Her visual fields were full
Ultrasonography of the orbit did not reveal any abnormality however Doppler studies showed reversal of blood flow and early arterialization of superior ophthalmic vein (fig 1).
CT scan showed preseptal swelling, thickening of the recti muscles and dilatation of the superior ophthalmic vein on right side (fig 2).
The facility of cerebral angiography was not available in our hospital. Based on her clinical findings, Doppler study and CT scan she was diagnosed as a case of Indirect Carotid cavernous fistula.
She was managed conservatively and given 0.5% Timolol eye drops twice daily and Tears Naturale II eye drops TID. The intraocular pressure dropped to 22 and 15 mm Hg in right and left eye respectively. Her cough responded to anti histamines and anti tussives and there was significant improvement in her headache. She was referred to neurosurgeon who advised continuation of the treatment and follow up at six monthly intervals.
The carotid cavernous fistulas (CCFs) are abnormal communications between carotid arterial system and cavernous sinus. The direct fistulas have a communication between internal carotid artery arid cavernous sinus whereas in indirect fistulas there is a communication between cavernous sinus and one of the branches of internal carotid artery. The direct fistulas are more common in young male while the indirect variety is more in pre-menopausal, female with a 7:1 female to male ratio pointing towards an underlying hormonal association.
Indirect CCF typically occurs spontaneously with milder signs and symptoms3 and has been shown to be associated with carotid artery aneurysm, fibromuscular dysplia. Ehlers danlos syndrome, atherosclerotic vascular disease, pregnancy and straining. This vascular leak results in a rise in intravenous pressure and change in rate and direction of blood flow through the ophthalmic veins along with reduced arterial blood flow to the orbit and caranial nervesin the cavernous sinus. Patients with CCF may initially present to an ophthalmologist with decreased vision, conjunctival chemosis, external ophthalmologist and proptosis4. it mimics acute angle closure glaucoma, thyroid eye disease, orbit pseudotumor, ch. Counjuctivitis, orbital casulitis and Tolosa-hunt syndrome5,6 however computed tomogaraphy (CT) magnetic resonance imaging (MRI) and orbital echography often help to confirm the diagnosis. Orbital Doppler may demonstrate a reversal in the direction and rate of blood flow in the superior ophthalmicvein1.
The definitive diagnostic test is cerebral arteriography with selective catheterization of the internal and external carotid arteries on both sides, so thal all arterial contributions to the fistulae can be visualized, angiogtaphy unequivocally demonstrates the fistula which is help full in case active intervention is planned CT Scanning and MRI are the preferred examination as they depict peripheral pathologies associated with CCFs and have a much lower incidence of complications.
Management of these cases involves care of exposure keratopathy and treatment of glaucoma Dural CCFs sometimes resolve spontaneously. In low risk cases manual carotid artery compression may be attempted because this therapy has a cure rate of almost 30%4. Active intervention is indicated in high risk paints who present who severe, proptosis, visual loss or cranial nerve plasy. In such patients endovascular embolization remain the treatment of choice.
Once the fistula is closed the patients starts improving in hours to days however the extent and rate of recovery depends upon the severity of signs and length of time the fistula was present.
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