British Journal of Radiology (2006) 79, 1007-1008
© 2006 British Institute of Radiology
doi: 10.1259/bjr/26714921
A red eye
D C Howlett, FRCR1,
G M T Watson, FRCR1,
M A Jeffree2 and
D Garlick, FRCR, FRCS3
Departments of 1 Radiology, Eastbourne District General Hospital, 2 Neuroradiology Hurstwood Park Neuroscience Centre, 3 Ophthalmology, Eastbourne District General Hospital, Kings Drive, Eastbourne, East Sussex BN21 2UD, UK
Correspondence: Dr D C Howlett, Eastbourne District General Hospital, Kings Drive, Eastbourne, East Sussex BN21 2UD, UK. E-mail: david.howlett{at}esht.nhs.uk
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Introduction
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An 86-year-old male, previously fit and well, presented to ophthalmology outpatients with a 10 day history of right temporal headache radiating to his ear and associated double vision. His general practitioner had initially suspected a diagnosis of temporal arteritis and started him on oral steroid medication, but this had not alleviated his symptoms.
On examination, there was a mild (5 mm) right sided proptosis with evidence of marked conjunctival chemosis, and mild ophthalmoplegia of lateral and upward gaze. The proptosis was non-pulsatile and no bruit was audible over the globe. The pupil appeared normal, as did the retina, but there was mild decreased visual acuity in the right eye with some elevation in intraocular pressure also noted. The temporal arteries were non-tender. Clinical examination was otherwise unremarkable and laboratory indices, including erythrocyte sedimentation rate, were within normal limits.
The patient was referred for MRI of the orbits. Axial T2 weighted images are demonstrated at the level of the optic nerve (Figure 1
) and superior orbit (Figure 2).
What abnormalities are present? What is the likely diagnosis? How could this be confirmed?
The MR images demonstrate a mild right proptosis with associated diffuse thickening of the extraocular muscles and there is some distortion of the retrobulbar fat. The right superior ophthalmic vein is dilated when compared with the normal left side (Figure 2
). The cavernous sinuses appear within normal limits.
The most likely diagnosis is that of a carotid-cavernous dural arteriovenous fistula (CCDAVF) with the fistula draining into the right superior ophthalmic vein.
To confirm this diagnosis, the patient initially underwent colour Doppler ultrasound of the superior ophthalmic vein, which contained arterial flow, and he then proceeded to carotid angiography. Selective right internal and external carotid injections confirmed a right sided CCDAVF that received arterial supply from the right meningohypophyseal trunk and also the middle meningeal artery. The fistula drained predominantly into the superior ophthalmic vein (Figure 3).
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Figure 3. Lateral view from a carotid angiogram during arterial phase following selective right internal carotid artery injection. There is a carotid cavernous fistula present which drains into a dilated right superior ophthalmic vein(arrows).
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Due to the patient's age and his good response to conservative measures to reduce intraocular pressure, it was decided not to undertake invasive treatment of the fistula initially and the patient is currently stable on follow-up.
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Discussion
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CCDAVFs tend to occur in older patients and may be associated with sphenoid sinusitis, cavernous sinus thrombosis or previous intracranial surgery [1]. CCDAVFs may receive arterial supply from branches of the internal or external carotid arteries, or more commonly from both [2]. These dural fistulae most commonly drain into the superior ophthalmic vein, although drainage may also occur into the contralateral cavernous sinus, into the sphenoparietal sinus or into the inferior petrosal sinus [3]. Many of these indirect fistulae are low flow and they may be associated with an insidious clinical course, making diagnosis difficult. Fast flowing, often solitary, direct fistulous communications may occur between the intracavernous internal carotid and the venous drainage system, often secondary to trauma or a ruptured aneurysm. Due to their high flow characteristics these lesions often present fulminantly, but they are not technically dural fistulae.
CCDAVFs tend to present with symptoms relating to increased pressure within the orbit due to increased arterial flow and also impaired venous drainage with orbital congestion. Conjunctival chemosis and proptosis are the most common symptoms. Diplopia secondary to muscle congestion, cranial nerve palsy, headache and tinnitus also occur [4]. Raised intraocular pressure and decreased visual acuity may be present, and there is a recognized association with central retinal vein thrombosis. A bruit is present on auscultation in up to 50% of patients [5]. A unilateral CCDAVF can cause bilateral eye symptoms due to crossover flow between the cavernous sinuses and occasionally the fistula may present with contralateral eye signs due to ipsilateral ophthalmic vein thrombosis with venous diversion [5].
If the dural fistula drains posteriorly into the inferior petrosal sinus, eye signs may be absent, the so-called "white-eyed shunt", and these patients may present with isolated 3rd or 6th cranial nerve palsies [3].
CT is the initial investigation of choice in the diagnosis of CCDAVF and MR is often complementary [6]. These modalities may demonstrate proptosis, thickening of the extraocular muscles, oedema of the retrobulbar fat and dilatation of the superior ophthalmic vein and cavernous sinus. There may be a paucity of signs on CT/MR in some patients, with the superior ophthalmic vein and cavernous sinus apparently normal, particularly in low flow fistulae. Doppler ultrasound may be a useful adjunct, but cerebral angiography is currently the most accurate modality for diagnosis of CCDAVF and should be undertaken if there is clinical suggestion of fistula, even if other imaging findings are apparently negative. Dilatation of the superior ophthalmic vein most commonly occurs secondary to CCDAVF, but may also be observed in other conditions producing increased venous pressure due to mass effect, including thyroid eye disease, orbital inflammatory syndromes and cavernous sinus thrombosis or tumour [1]. Doppler ultrasound may be helpful in confirmed arterialized flow in the vein, as in our case, indicating the diagnosis of dural cavernous fistula.
There are various treatment options available for CCDAVF. In the elderly or unfit, if vision is stable it may be appropriate to use conservative measures in the first instance, aimed at reducing intraocular pressure, e.g. acetazolamide and topical Beta-blockers. Carotid-jugular compression may also be appropriate in some patients, particularly in those who have had subtotal endovascular fistula closure [1]. This technique involves transient and repeated manual compression of the carotid artery and jugular vein by the patient and has been shown to promote fistula thrombosis.
It is contraindicated in the presence of carotid arteriosclerosis or hypercoagulable state and initial compressions should be performed under observation [1]. Patients with severe symptoms or evidence of progressive visual loss require prompt angiography and closure of the fistula. This may be approached via arterial or venous routes and coils or balloons can be used. Direct embolisation can be achieved utilizing a superior ophthalmic vein approach [7].
Received for publication June 24, 2005.
Revision received September 6, 2005.
Accepted for publication October 11, 2005.
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References
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- Rael J R, Jacobs JM, Orrison WW. Neuro-intervention. In: Neuroimaging volume 1. Philadelphia, USA: WB Saunders Company, 2000:280–9
- Barrow DL, Spector RH, Braun IF, et al. Classification and treatment of carotid cavernous sinus fistulas. J Neurosurg 1985;62:248–56.[Medline]
- Acierno MD, Trobe JD, Cornblath WT, Gebarski SS. Painful oculomotor palsy caused by posterior – draining dural carotid – cavernous fistulas. Arch Ophthalmol 1995;113:1045–9.[Abstract]
- Newton TH, Hoyt WF. Dural arterio-venous shunts in the region of the cavernous sinus. Neuroradiology 1980;1:71–81.[CrossRef]
- Halbach VV, Higashida RT, Hieshema GB, et al. Dural fistulas involving the cavernous sinus: results of treatment in 30 patients. Radiology 1987;163:437–42.[Abstract/Free Full Text]
- Uchino A, Hasuo K, Matsumoto S, Masuda K. MRI of carotid – cavernous fistulas. Comparisons with post contrast CT. Clin Imaging 1992;16:263–8.[CrossRef][Medline]
- Berlis A, Klisch J, Spetzger U, et al. Carotid cavernous fistula: embolisation via a bilateral superior ophthalmic vein approach. Am J Neuroradiol 2002;23:1736–8.[Abstract/Free Full Text]
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Introduction
Discussion
