Carotid-Cavernous Fistula

Carotid-Cavernous Fistula
Other Names	Caroticocavernous Fistula
A Barrow Type D carotid-cavernous fistula on CT angiography
Identifiers
ICD-9	437.3
ICD-10	I67.1
Outside Resources
EyeWiki	Carotid Cavernous Fistula
Radiopaedia	Carotiocavernous Fistula

Overview

Carotid-cavernous fistula, or caroticocavernous fistula, is an acquired communication between the carotid artery system and the cavernous sinus.

Pathophysiology

Relevant Anatomy

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  Contents of the cavernous sinus

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  Bilateral cavernous sinus contents with communication through the circular venous plexus

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  Lateral view of the cavernous sinus in the skull base

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  Axial view of the cavernous sinus

Classification

Broadly, carotid-cavernous fistulas can be characterized as either direct or indirect. Direct fistulas have a direct communication between the intracavernous ICA itself and the cavernous sinus. Indirect fistulas describe communications from the carotid system to the cavernous sinus through a third vessel, a branch of the ICA or ECA. The most common classification system for carotid-cavernous fistulas is the Barrow classification system, first described in 1985.

Barrow Classification for Carotid-Cavernous Fistula

Class	Communication	Description
A	Direct	Flow from the intracavernous ICA directly into the cavernous sinus
B	Indirect	Flow from a branch of the intracavernous ICA into the cavernous sinus via a dural shunt
C	Indirect	Flow from a meningeal branch of the ECA into the cavernous sinus via a dural shunt
D	Indirect	Multiple dural shunts flowing into the cavernous sinus from the ICA and ECA systems (Class B + C)

Additional descriptive terms used to classify or categorize carotid-cavernous fistulas are similar to other arteriovenous fistulas, including high flow vs low flow and underlying etiology.

Diagnosis

Imaging

CT angiography or MR angiography are typically the first line imaging modality based on patient presentation and ease of availability in the emergency department. Angiography is the gold standard of diagnostic imaging in order to confirm the communication, as well as describe the location and flow of the fistula.