Tip of the Month
Publishing date: October 2017
The Science behind the Tip
A carotid – cavernous sinus fistula is an abnormal vascular communication between the carotid artery system and the cavernous sinus. This can result in raised episcleral venous pressure and is a rare cause of elevated IOP and glaucoma (1).
Most occur after trauma and result in pulsatile proptosis, engorgement of the episcleral veins and a bruit. The remainder occur spontaneously with an insidious onset, mainly in middle-aged women. Because these dural carotid-cavernous sinus fistulas are low flow, less severe symptoms occur (2). Prominent episcleral veins with minimal proptosis is found and two thirds have raised IOP or glaucoma (1).
Non-invasive imaging techniques can be used to confirm the diagnosis (3). The most common treatment is occlusion of the fistula via a transarterial or transvenous route. This results in restoration of normal orbital and intracranial blood flow and reduction of IOP in most cases (2).
Contributor: John F Salmon MD - Oxford
1. Ishijima K, Kashiwagi K, Nakano K et al., Ocular manifestations and prognosis of secondary glaucoma in patients with carotid-cavernous sinus fistula. Jpn J Ophthalmol 2003; 47: 603-8
2. Miller NR. Dural carotid-cavernous fistulas: epidemiology, clinical presentation and management. Neurosurg Clin N Am 2012; 23: 179-92.
3. Gandi D, Chen J, Pearl M et al. Intrancranial dural arteriovenous fistulas : classification, imaging findings and treatment. Am J Neuroradiology 2012; 33: 1007-13.
Tip Reviewer: Roger Hitchings
Tip Editor: John Salmon