A 30 year old man, who after suffering an assault was taken to the emergency department of the Hospital Universitario La Paz due to multiple incised wounds to the face, neck, scalp and left hand. On arrival he was admitted to the Intensive Care Unit for marked hypothermia, Glasgow 10, severe metabolic acidosis, hypokalaemia and acute renal failure, requiring mechanical ventilation for 24 hours. After resolution of the acute organic symptoms and primary suturing of the wounds, the patient was transferred to the ward after 48 hours, and was discharged from hospital one week after admission.

Six days after discharge, the patient returned to the emergency department for pain and swelling in the left preauricular region, underlying the surgical scar of one of the facial wounds. Symptoms included tinnitus and physical examination revealed limited oral opening and a left preauricular lump measuring 2 × 2 cm, soft and pulsatile on palpation and inspection. Auscultation of the mass revealed a murmur synchronous with arterial systolic flow.
A parotid ultrasound was performed, showing an image compatible with a high-flow left intraparotid arteriovenous fistula.
The cervicofacial and cervical computed tomography (CT) scan showed an image suggestive of a vascular pocket measuring 36 × 25 × 24 cm, located behind the left mandibular vertical branch, between the deep and superficial lobe of the parotid gland, at the level of the retromandibular vein. There is a probable arterial afferent image coming from branches of the external carotid artery, with venous drainage towards the external jugular vein.

With a view to a diagnosis of certainty, an angiography was carried out showing a vascular lesion whose fundamental afferent is the proximal portion of the internal maxillary artery and whose venous drainage is directed superiorly towards the pterygoid plexus and descending towards the external jugular vein. There is also retrograde flow from the facial artery into the pouch. Treatment is carried out on the spot by embolisation via microcatheterisation of the internal maxillary artery and occlusion with a 3 × 8 mm platinum coil. However, the final angiographic control showed late retrograde filling from the left facial artery.

The patient was discharged with outpatient follow-up, with evident clinical improvement. Angio-CT revealed occlusion of the internal maxillary artery with closure and thrombosis of the fistulous pocket. Outpatient follow-up at 1 and 6 months showed no complications or recurrence.