Incidence of depression of the medial orbital wall without a recent trauma event.

The aim of this study was to see how frequently depression of the orbital medial wall can be found on computed tomographic (CT) imaging of patients without a recent trauma event. A total of 14,628 CT scans (12,515 brain CT scans and 2113 three-dimensional facial CT scans) of patients with no recent trauma event (defined as a facial trauma within 1 mo) were reviewed. If there was a depression of more than 3 mm on the medial wall compared with the contralateral side in the axial view, the scan was included in the "depression or asymmetry" group. In the depression or asymmetry group, old fractures and recent fractures were differentiated according to the degree of swelling of the medial rectus muscle and soft tissue swelling. Among the 14,628 CT scans with no recent facial trauma event, 836 cases (5.7%) had depression or an asymmetric medial wall. Most (94.3%, 788 cases) of the 836 cases were discovered to have an old medial wall fracture, whereas 39 cases (4.7%) were reported to have a recent medial wall fracture despite not having a recent facial trauma event. Only 9 cases (1.1%) were revealed to have a mucocele. It is noteworthy that 5.3% (788 cases among the 14,628 cases) had an old medial wall fracture despite not having any facial trauma within 1 month. The reason for this relatively high ratio is thought to be because medial fractures are often undetected with conventional plain x-ray imaging.