Intraorbital arteriovenous fistulas: illustrative case

Abstract

Background: Intraorbital arteriovenous fistulas (ioAVFs) represent a rare but distinct entity of arteriovenous shunts, separate from the more common carotid-cavernous fistulas (CCFs). There is currently no consensus on the optimal treatment approach for ioAVFs, necessitating analysis of available cases to guide clinical decision-making and establish effective management strategies.

Observations: A systematic literature review revealed a total of 28 ioAVF cases reported since 1978. An additional illustrative case is included. Intraorbital AVFs present with similar symptoms as the CCFs such as skin changes (chemosis, ecchymosis, erythema; 86.2%), proptosis (72.4%), and headaches (34.5%). Visual impairment was observed in 12 cases (41.4%); ophthalmoplegia occurred in 8 cases (27.6%). Five patients (17.2%) presented with an afferent pupillary defect. All patients underwent catheter angiography for their diagnostic workup. The ophthalmic artery (OA) was a direct feeder to the fistula in almost all patients (96.6%). Additional feeding vessels included the facial artery, sphenopalatine artery, middle meningeal artery, internal maxillary artery, and superficial temporal artery. Venous drainage was mainly via the superior ophthalmic vein (SOV). Other draining veins involved the inferior ophthalmic vein, facial vein, superior temporal vein, basal vein of Rosenthal, and superior sagittal sinus. Spontaneous resolution occurred in 5 cases (< 20%). Treatment was reported in 21 cases and included embolization (66.7%), resection (14.3%), or combined techniques (19.0%). Embolization was performed most often transvenously (14 cases). Three cases were embolized via direct puncture. A transarterial approach was selected in 6 cases. The OA was embolized directly (distal to the central retinal artery) in 2 cases, including the illustrative case. The average follow-up was 7.8 months (range 3 days-3 years). Overall, treatment was successful with a high cure rate (85.7%). Complications included extensive hemorrhage during transvenous embolization in 1 case and profound thrombosis of the SOV in 2 cases.

Lessons: Intraorbital AVFs are characterized by direct inflow via the OA. Treatment can be challenging. A multimodal approach, including observation, can result in high cure rates. Transvenous embolization is the most commonly performed intervention. Embolization via the OA is an option, but carries the risk of permanent visual deficit. https://thejns.org/doi/10.3171/CASE24857.

Keywords: arteriovenous fistulas; case report; endovascular embolization; orbit.

FIG. 1.

PRISMA flow diagram illustrating the study selection process, starting with 125 articles identified, 104 of which progressed to the screening stage. After a full-text review, 25 articles were included in the final analysis. Excluded studies are categorized by reasons such as unavailable full-text paper, study unavailable in the English language, or unconfirmed ioAVF diagnoses.

FIG. 2.

A: Digital substraction angiogram, lateral view, depicting a pure orbital AVF (asterisk; ICA injection). The patient was symptomatic with ecchymosis and double vision. B: For embolization, a microcatheter was placed directly into the OA past the origin of the central retinal artery. C: The postembolization angiogram is consistent with complete embolization of the orbital component (asterisk). Only a faint intradural shunt remains (black arrow). Ecchymosis and orbital edema completely resolved. The double vision improved substantially.