Imaging Studies
Radiographic evaluation of suspected medial wall fractures has evolved over the past several years. Conventional radiography or routine orbital x-rays generally are not helpful because of the compact overlapping anatomy of this region and the thinness of the medial orbital wall. Nonetheless, x-ray signs to look for include a disruption in the medial orbital wall, opacification of the ethmoid sinus, and presence of air in the orbit.
CT scan has greatly improved the evaluation of orbital fractures, and it should be completed in all patients suspected of having such an injury. Optimal information can be gained from both axial and coronal cuts of bone and soft tissue images (see the images below). With these appropriate views, the size, morphology, and exact seat of the fracture, which has the possibility to extend to the optic canal, can be visualized.
Coronal CT scan of the orbits of a patient with an injury to his right orbit as a result of blunt trauma from a fist reveals a right medial orbital wall fracture with the medial rectus entrapped.
CT scan accurately localizes the bone fragments of the fractured lamina papyracea even if the orbital sinus adjacent to the fracture is opacified. A variable degree of medial displacement of the thin lamina papyracea may be present, and density is often increased in the ethmoidal sinuses from edema and blood accumulation. CT scan also detects entrapment of the medial rectus muscle, recognized by displacement of the muscle into the fracture site, with or without bone displacement. In the pediatric trapdoor fractures described earlier, clinical evidence of entrapment will not necessarily correlate with the CT scan findings. In these cases, in which a trapdoor-type defect has occurred, there will be minimal or no evidence of bone displacement. In addition, the medial rectus could appear in a normal position, but the surrounding connective tissue is seen entrapped in the location of the fracture. A more rounded appearance of the medial rectus adjacent to the bone should also raise the index of suspicion for a trapdoor-type fracture. [13]
A CT scan reliably demonstrates whether acute proptosis in a patient is secondary to orbital hemorrhage or orbital emphysema. Echography also could aid in distinguishing these 2 distinct entities. B-scan ultrasound has proven to be reliable in diagnosing medial wall fractures because a good correlation between ultrasound and CT scan was found. However, edema, hemorrhage, emphysema, and swelling may influence the accuracy of the scan.
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This 55-year-old man sustained an injury to his right orbit as a result of blunt trauma from a fist; shown in primary position.
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Patient with an injury to his right orbit as a result of blunt trauma from a fist in right gaze, showing full abduction of the right eye.
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Patient with an injury to his right orbit as a result of blunt trauma from a fist in left gaze, showing poor adduction of the right eye.
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Coronal CT scan of the orbits of a patient with an injury to his right orbit as a result of blunt trauma from a fist reveals a right medial orbital wall fracture with the medial rectus entrapped.
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Axial CT section.
