Parachordal fistula--a case report and a short review.

Arteriovenous shunts of the neck and facial region rarely involve the external carotid artery and its branches. Most cases are considered to be iatrogenic or related to trauma but congenital shunts are rare. Parachordal arteriovenous fistulae are a group of embryologically derived arteriovenous shunts caused by defects involving the notochord, giving rise to cranial and paraspinal shunts. In the cranial regions, these shunts involve exclusively the metameric arteries--maxillary, ascending pharyngeal, occipital and vertebral. Signs and symptoms are variable, depending on the feeding vessel but also on the characteristics of the draining pathway. We report the case of a 17-year-old male patient with a shunt between the right internal maxillary artery and right external jugular vein detected at the age of 6, not associated with trauma, which we decided to treat because of an enlargement of the right cardiac atrium detected on routine examination. Digital subtraction angiography was performed to characterize the shunt followed by partial embolization with ballooning, coiling and Onyx injection. Echographic control 6 months after the procedure was compatible with complete occlusion of the shunt. We also perform a short review on this extremely rare entity.