Evaluation of Angiographically Occult Spinal Dural Arteriovenous Fistulae With Surgical Microscope-Integrated Intraoperative Near-Infrared Indocyanine Green Angiography: Report of 3 Cases

BACKGROUND: Spinal dural arteriovenous fistulae (dAVFs), are lesions involving an aberrant connection between a radicular feeding artery and the venous system of the spinal cord at the dural sleeve of the nerve root. When rare dAVFs are occult on digitally subtracted catheter-based angiography, they present a diagnostic and therapeutic challenge. OBJECTIVE: We report 3 cases of angiographically occult spinal dAVFs that were evaluated during surgery with indocyanine green (ICG) fluorescent microscope-integrated angiography. METHODS: Three patients with clinical and magnetic resonance imaging features suggestive of a spinal dAVF but no abnormality on digital subtraction angiography underwent surgical exploration with the aid of microscope-integrated ICG video-angiography. RESULTS: In all 3 cases, ICG identified the intradural vein draining the fistula, clearly distinguishing it from an artery or uninvolved medullary vein. CONCLUSION: ICG angiography can rapidly identify a draining vein as it enters the spinal canal even in dAVFs not identifiable on catheter-based digital subtraction angiography.