Transvenous embolization for an intraosseous clival arteriovenous fistula via a proper access route guiding a three-dimensional fusion image: illustrative case

BACKGROUND: Intraosseous clival arteriovenous fistulas (AVFs), in which the shunt drains extracranially from the posterior and anterior condylar veins rather than from the cavernous sinus (CS), are rare. Targeting embolization of an intraosseous clival AVF is challenging because of its complex venous and skull base anatomy; therefore, a therapeutic strategy based on detailed preoperative radiological findings is required to achieve a favorable outcome. Here, the authors report the successful targeted embolization of an intraosseous clival AVF using an ingenious access route. OBSERVATIONS: A 74-year-old woman presented with left-sided visual impairment, oculomotor nerve palsy, and right facial pain. A fusion image of three-dimensional rotational angiography and cone-beam computed tomography revealed a left CS dural AVF and a right intraosseous clival AVF. The shunt flow of the clival AVF drained extracranially from the posterior and anterior condylar veins via the intraosseous venous route. Transvenous embolization was performed by devising suboccipital, posterior condylar, and intraosseous access routes. The symptoms resolved after the bilateral AVFs were treated. LESSONS: Accurate diagnosis and proper transvenous access based on detailed intraosseous and craniocervical venous information obtained from advanced imaging modalities are key to resolving intraosseous clival AVF.