|Year : 2016 | Volume
| Issue : 1 | Page : 69-71
Intractable glaucoma: Hunt for carotico-cavernous fistula
Sushil Ghanshyam Kachewar, Smita Balwant Sankaye
Radio-diagnosis Department, PDVVPF's Medical College, VIMS, Ahmednagar, Maharashtra, India
|Date of Web Publication||4-Mar-2016|
Sushil Ghanshyam Kachewar
Professor, Radio-diagnosis Department, PDVVPF's Medical College, VIMS, Ahmednagar - 414 111, Maharashtra
Source of Support: None, Conflict of Interest: None
Carotico-cavernous fistula is a dural arteriovenous fistula arising from abnormal arteriovenous shunting between the internal carotid artery and the cavernous sinus. Imaging features in a rare case presenting with intractable glaucoma due to bilateral carotico-cavernous fistula following head injury are reported in this article.
Keywords: Carotico-cavernous fistula, color Doppler ultrasound, intractable glaucoma, magnetic resonance imaging, nonpulsatile proptosis
|How to cite this article:|
Kachewar SG, Sankaye SB. Intractable glaucoma: Hunt for carotico-cavernous fistula. J Mahatma Gandhi Inst Med Sci 2016;21:69-71
| Introduction|| |
Carotico-cavernous fistula (CCFs) arise due to abnormal arteriovenous communication between the internal carotid artery and the cavernous sinus. Out of the different etiologies, trauma is an important one. Diagnosis of post traumatic CCF is all the more important as the incidence of trauma is on rise and it is the young working male who is most commonly affected. 
| Case Report|| |
A 20-year-old male suffered a road traffic accident resulting in fracture of right maxillary and zygomatic bones. Approximately 6 months later, he noticed mild blurring of vision. Hence he was referred for ultrasound of his eyes and magnetic resonance imaging (MRI) brain and orbit.
On clinical examination, the vision in his both eyes was 6/9 and intraocular pressure was 28 mm of Hg. There were few dilated circumciliary blood vessels and episcleral veins. On palpation of globe, there was no pulsation felt or on auscultation of orbit no bruit was heard. Patient was treated with the intraocular pressure lowering agents to prevent glaucomatous damage of optic nerve. But the patient did not respond to pharmacotherapy. Unfortunately, other details of gonioscopy findings, standard automated perimetry, and optical coherence tomography are not available with the author whose interest lies on concentrating on imaging findings in this case.
High-frequency ultrasound demonstrated dilated and tortuous superior ophthalmic veins bilaterally [Figure 1]. Color flow study showed a typical ying-yang flow pattern in dilated tortuous superior ophthalmic veins [Figure 2]. On Doppler study there was arterialization of the flow within the superior ophthalmic veins with peak systolic velocity of superior ophthalmic veins approximately 30-40 cm/s [Figure 3]. MRI of orbits confirmed bilateral carotico-cavernous fistulae (CCFs) [Figure 4] and [Figure 5]. The patient was referred to higher center for further management. Follow-up from the higher center mentioned that the raised intra-ocular pressure normalized only after the fistulae were embolized by using coils.
|Figure 1: High-frequency ultrasound demonstrated dilated and tortuous superior ophthalmic veins in both orbits|
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|Figure 2: Color flow study showed a typical ying-yang flow pattern in dilated tortuous superior ophthalmic veins|
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|Figure 3: Pulse Doppler study shoes arterialization of the flow within the superior ophthalmic veins with peak systolic velocity of superior ophthalmic veins approximately 30-40 cm/s|
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|Figure 4: T2-weighted axial magnetic resonance imaging of orbits confirmed dilated and tortuous superior ophthalmic veins in both orbits|
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|Figure 5: Magnetic resonance angiography image shows tortuous superior ophthalmic veins directly communicating with prominent cavernous sinus suggestive of bilateral carotico-cavernous fistulae|
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| Discussion|| |
CCFs occur due to abnormal arteriovenous shunting between the internal carotid artery and the cavernous sinus and can even lead to blindness if left untreated. Young men are more prone to develop traumatic carotid-cavernous fistulas, as there is increased incidence of trauma in them. 
The cavernous sinuses consist of extradural venous plexuses surrounded by a dural fold. The intra-cavernous internal carotid artery with its peri-arterial sympathetic plexus runs between the venules of the parasellar venous plexus. CCFs can result from traumatic laceration of the carotid artery or from rupture of an aneurysm into the surrounding venous sac establishing a direct arteriovenous fistula between the internal carotid artery and the venous spaces of the cavernous sinus. This results in short-circuiting of the arterial blood into the venous system of the cavernous sinuses. Direct CCFs, which represent 70-90% of all CCFs in most series, are characterized by a direct connection between the intra-cavernous segment of the internal carotid artery and the cavernous sinus. These fistulae usually have high rates of arterial blood flow and most commonly are caused by a single traumatic tear in the arterial wall.
Dural CCFs are formed by a communication between the cavernous sinus and meningeal branches of the internal carotid artery, external carotid artery, or both. These fistulae develop without any antecedent trauma or manipulation. They usually have low rates of arterial blood flow and almost always produce symptoms and signs spontaneously. The lesions may represent congenital arteriovenous malformations, which develop spontaneously or in association with atherosclerosis, systemic hypertension, collagen vascular disease, pregnancy, and during or after childbirth. 
Most of the patients with a direct CCFs experience progressive ocular complications if the fistula is left untreated. Increasing proptosis, conjunctival chemosis, and visual loss occur over months to years, with central retinal vein occlusion and secondary glaucoma representing the most severe ocular complications.
Past history of significant trauma and fracture of base of skull is important in the diagnosis of post-traumatic direct CCFs. Patients may present with redness of the eye, diplopia, buzzing or swishing sounds, decreased vision, bulging eye and facial pain in the distribution of the first (and rarely the second) division of the trigeminal nerve.
Computed tomography scan, MRI, and orbital ultrasound often help to confirm the diagnosis, demonstrating extra-ocular muscle enlargement, dilation of one or both superior ophthalmic veins, and enlargement of the affected cavernous sinus. In all CCFs, the definitive diagnostic test is cerebral arteriography with selective catheterization of the internal and external carotid arteries on both sides, so that all arterial contributions to the fistulae can be visualized. Intra-arterial subtraction angiography is generally the preferred technique. Because of the invasive nature of the procedure and radiation hazard, MRI is nowadays a preferred imaging modality. Noninvasive imaging and multiplanar technique as well as MR angiography and MR venography helped MRI to replace the conventional imaging modalities in the diagnosis of CCFs.
The optimal treatment of direct CCFs is closure of the abnormal arteriovenous communication with preservation of internal carotid artery patency. ,
The early diagnosis and management of CCFs in individuals with pharmacologically nonresponding and progressively worsening glaucoma is necessary to prevent the permanent loss of ocular vision. Imaging studies thus play a vital role in this complex issue.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]