[Delayed epidural bleeding caused by traumatic pseudoaneurysm of the middle meningeal artery: case report].

A 16-year-old man who presented with delayed bleeding of epidural hematoma is reported. Computed tomography (CT) on admission demonstrated a small amount of right epidural hematoma and a small fracture of the right lateral orbital wall. He was treated conservatively. Repeated CT scans and magnetic resonance (MR) imaging revealed no growth in the epidural hematoma, but demonstrated flow void sign at the medial side of the hematoma on MR images. After 8 days, CT scan presented the regrowth of the hematoma, so we planned the removal of hematoma. Epidural hematoma due to the rupture of a traumatic pseudoaneurysm of the middle meningeal artery is rare. Especially, since traumatic lesions were diagnosed by CT, it was unusual to be able to diagnose the pseudoaneurysm of middle meningeal artery preoperatively. The cases of epidural hematoma treated conservatively should be followed up by MR imaging and MR angiography using the fat suppression technique.