Superficial temporal artery pseudoaneurysm: ultrasonographic diagnosis in the ED

Superficial temporal artery pseudoaneurysm (STAP) is an uncommon complication of blunt and penetrating trauma. It accounts for only 1% of all traumatic aneurysms. Superficial temporal artery pseudoaneurysm usually has the characteristic appearance of a cystic pulsatile mass in the region of the superficial temporal artery. Here we present a case of posttraumatic STAP detected by US in the emergency department (ED). A 58-year-old woman presented to our ED with a tender right frontoparietal mass. Two weeks before presentation, the patient was involved in a motor vehicle accident (MVA) and was taken to the state hospital where the result of a computed tomography scan of the head was shown to be normal except for right frontoparietal soft tissue swelling and hematoma formation. A few days after discharge, the diameter of the soft tissue swelling decreased and the patient was well. However, 2 weeks after the MVA, the patient presented to our ED with a throbbing headache and dramatic increase in the diameter of the lesion. Examination showed a 5 x 5-cm swelling, which was soft, tender, and fluctuant on palpation. The swelling was not pulsatile. Ultrasound was performed using a 7.5-MHz probe and demonstrated a well-defined, pulsatile, anechoic mass measuring approximately 50 x 50 mm in diameter. Ultrasound is a valuable and readily available tool in the ED to confirm the diagnosis.