Traumatic pseudoaneurysm of the middle meningeal artery: possible indicators for early diagnosis in the computed tomography era

Objective and ImportanceTraumatic pseudoaneurysms of the middle meningeal artery, which are associated with high mortality, are difficult to detect early by CT. We provide serial CT scans to show the steps of their formation and suggest characteristics that could be useful in the detection.Clinical PresentationA 25-year-old man was initially in deep coma had an anisocoric pupil after a traffic accident. Brain CT showed basal skull fracture and traumatic subarachnoid hemorrhage with severe brain swelling. Emergent decompressive craniectomy was performed, and 2 days later, an EDH appeared at the left temporal fossa. Careful examination of the image revealed a hypodense nodule inside the acute hematoma. He underwent craniotomy to remove the hematoma. Serial CT of the residual hematoma showed the gradual development of an organized hematoma around the hypodense nodule. The nodule had low density, which was strongly enhanced on CT after injection of contrast medium. The nodule was highly suspected to be a vascular lesion. A middle meningeal artery pseudoaneurysm was discovered through a 3-dimensional computed tomographic angiography. He underwent another craniotomy to remove the pseudoaneurysm.InterventionThe diagnostic approach was CT, 3-dimensional CT, and craniotomies.ConclusionFour CT findings may be useful for early diagnosis: (1) basal skull fracture in the temporal region; (2) hypodense nodule within an acute hematoma; (3) hypodense nodule within an organized and encapsulated hematoma; and (4) strong and homogenous enhancement of the hypodense nodule within an organized and encapsulated hematoma. Three-dimensional computed tomographic angiography is an effective and noninvasive tool to confirm this diagnosis.