Medial blowout fracture - Clinical Tree

Key points

Definition: Medial blowout fractures (MBOFs) result from direct trauma to the orbit transmitting most of the force to the globe. This causes the orbital contents to “blow out” through the path of least resistance, usually the paper-thin lamina papyracea or orbital floor.
Classic clue: Bowing or displacement of the medial orbital wall in a patient with known or presumed facial trauma and soft tissue density in the adjacent ethmoid sinus. Some patients show enophthalmos, restrictive strabismus, or infraorbital numbness.
Trauma to the orbit may be isolated or may be part of a more generalized traumatic episode.
Patients who present with orbital trauma may not give a clear trauma history, either because of posttraumatic neurologic sequelae or because of something they ingested or imbibed previously.
MBOFs may initially appear to be the least of the patient’s problems and may be overlooked by the trauma team, including the radiology resident/fellow.
Many patients with MBOFs have old or new fractures and occasionally a combination of both, which the radiologist needs to deal with.

Computed tomography (CT) is the first line of imaging in patients with orbital trauma.
It may be necessary to add CT of the face and/or orbits to the imaging protocol if only brain CT is requested.

Medial bowing or displacement of the medial orbital wall.
Fracture may be visible through the bony cortex with or without displacement.
Bowing of the medial orbital wall may be so smooth that it appears developmental, particularly if the fracture is old.
New fractures usually have associated findings with soft tissue density extending into the ethmoid sinus and adjacent structures.
Air collections may be visible within the orbit and/or air-fluid levels.
Multiplanar imaging is helpful with axial, coronal, and sagittal views. Three-dimensional imaging is helpful and popular with clinicians.
Fractures may be bilateral. Bilateral fractures are unlikely to both be new and are more likely to comprise an old and a new fracture. Bilateral old fractures are often overlooked.

Most patients present to the emergency department with a history of known trauma to the face or orbit or with a history of suspected trauma to the head and face but are “not really sure” what happened.
Most fractures are secondary to personal altercations. More complex fractures are more likely to be related to motor vehicle accidents and falls.
Associated clinical findings may include:
- Enophthalmos
- Diplopia
- Orbital emphysema
- Paresthesia secondary to damage of the inferior orbital nerve

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