The incidence of PAVF is relatively rare among all dural vascular malformations. In a normal scenario, vertebral arteries should drain into the paravertebral venous plexus. However, in this particular patient, the vertebral arteries drained into the intravertebral veins and superior vena cava. It is important to note that angiography of vessels such as the thyrocervical trunks and the rib-cervical trunks is necessary to avoid misdiagnosis.
Complete embolization of the fistula requires a large number of coils, resulting in costly treatments[7]. To address this challenge, detachable coils plus Onyx are now commonly employed for cerebral vascular malformations embolization[8]. To our knowledge, There are limited case reports on detachable coils plus Onyx embolization for PAVF. The Onyx is a non-adhesive liquid that will not adhere to blood vessel walls or surrounding tissues, thus minimizing damage to normal tissue. When needed, its viscosity and injection speed can be adjusted to accommodate different vascular morphology and lesion conditions, enhancing precision and control during embolization process. Feng et al. emphasize that effective delivery of Onyx to target vessel relies on its excellent penetration, therefore if the fistula presents as high-flow, extensive and complex lesions, the surgeon may reduce the blood flow with coils, thus facilitating the molding of the Onyx[9]. Overall, The Onyx represents an ideal approach for multiple structurally complex arteriovenous malformations.
The PAVF described herein suggests that complete occlusion may not be achieved with detachable coils embolization alone, if this PAVF is characterised by high flow and extensive, the use of Onyx slows the blood flow and reduces the space, thus avoiding the overuse of detachable coils. Furthermore, the pre-operative intact head and neck MRI revealed an intravertebral flowing void effect, suggesting possible presence of PAVF in addition to other vascular malformations.