Figure 1
Facial views demonstrating the orbits
Orbital blow-out fracture
SectionHead & neck imaging
Case TypeClinical Cases
AuthorsH J Williams, A S Ahmed
Connected authors
29 years, male
Clinical History
The patient was involved in a fight and sustained a direct blow to the right orbit. There was marked swelling around the right orbit.
Imaging Findings
The patient was involved in a fight and sustained a direct blow to the right orbit. There was marked swelling around the right orbit. Facial x-rays showed air within the right orbit and a convex mass projecting into the roof of the right maxillary sinus. A CT scan was performed and this demonstrated a comminuted fracture of the orbital floor/superior wall of the maxillary antrum and herniation of intraorbital fat into the maxillary sinus.
Discussion
A blow-out fracture of the orbit results from a direct compressive force to the eye, e.g. from a tennis ball or fist. There is an acute increase in intraorbital pressure which is relieved by fracture through the weakest parts of the orbit. These are the thin plates of bone that form the orbital floor (roof of the maxillary antrum) and the medial wall of the orbit (lateral wall of the ethmoid sinuses). The orbital rim remains intact in pure blow-out fractures. Orbital contents may then herniate downwards through the orbital floor fracture into the maxillary sinus. On occipitomental (facial) x-rays this is seen as a convex mass projecting into the roof of the right maxillary sinus. This appearance has been likened to an opaque tear drop hanging from the roof of the antrum and may be the only radiographic evidence of a blow-out fracture.
Other signs of a blow-out fracture are air within the orbit (which has entered from the maxillary or ethmoid sinuses), an indistinct orbital floor on occipitomental views and opacification of the sinuses due to blood within them. An air-fluid level may be seen in the maxillary sinus. The fracture fragments are rarely demonstrated on plain films.
If the inferior rectus muscle or its sheath herniates through the fracture and becomes trapped, it may be compromised resulting in diplopia on looking down or straight ahead. Mild or transient diplopia can occur simply due to the periorbital oedema or haemorrhage. A CT scan is indicated if there is diplopia or restriction of eye movements, and to assess the extent of the injury. Direct coronal CT scans (with the patient prone) are best for demonstrating blow-out fractures. In the supine position, fluid and debris in the maxillary antrum can layer against the orbital floor and obscure soft tissue herniating through the fracture.For those patients in whom direct coronal scans are not possible (for example due to other injuries or if the patent is unable to co-operate), axial CT scans with coronal reconstructions are an alternative method of imaging, particularly with the use of multidetector CT .
The treatment of pure orbital blow-out fractures is often conservative but orbital floor repair may be necessary if there are complications such as inferior rectus muscle compromise. Surgery is rarely needed for medial wall fractures. Rarely fragments from an orbital floor fracture buckle up into the orbit, an injury referred to as a "blow-in" fracture.
Differential Diagnosis List
Orbital blow-out fracture
Final Diagnosis
Orbital blow-out fracture
References
[1] Raby N, Berman L, deLacy G. Face (Chapter 3). In Raby N, Berman L, deLacy G. Accident and Emergency Radiology: A Survival Guide. WB Saunders Company Ltd, London, pp 36-49 (1995).
[2] Barr RM, Gean AD. Craniofacial trauma (Chapter 3). In Brant WE, Helms CA (Eds) Fundamentals of Diagnostic Radiology, Second Edition. Lippincott Williams and Wilkins, Philadelphia, pp 49-77 (1999).
[3] Eagling EM. Eye and adnexal trauma (Chapter 11). In Skinner DV, Whimster F. Trauma, A companion to Bailey and Love's Short Practice of Surgery. Arnold, London, pp 123-34 (1999).
Case information
| URL: | https://www.eurorad.org/case/1547 |
| DOI: | 10.1594/EURORAD/CASE.1547 |
| ISSN: | 1563-4086 |
Figure 2
Coronal CT scans of the orbits
There is some opacification of the right ethmoid sinuses and probably fracture of the medial orbital wall. The orbital rim is intact.
There is some opacification of the right ethmoid sinuses and probably fracture of the medial orbital wall. The orbital rim is intact.
There is some opacification of the right ethmoid sinuses and probably fracture of the medial orbital wall.
Small fragments of bone are seen within the soft tissue protruding into the right maxillary antrum. The attenuation of the soft tissue is that of fat. There does not appear to be any herniation of the inferior rectus muscle. Note the absence of an effusion in the maxillary sinus.
Small fragments of bone are seen within the soft tissue protruding into the right maxillary antrum. The attenuation of the soft tissue is that of fat. There does not appear to be any herniation of the inferior rectus muscle. Note the absence of an effusion in the maxillary sinus.
Note the absence of an effusion in the maxillary sinus.
Coronal CT scans of the orbits
There is some opacification of the right ethmoid sinuses and probably fracture of the medial orbital wall. The orbital rim is intact.
There is some opacification of the right ethmoid sinuses and probably fracture of the medial orbital wall. The orbital rim is intact.
There is some opacification of the right ethmoid sinuses and probably fracture of the medial orbital wall.
Small fragments of bone are seen within the soft tissue protruding into the right maxillary antrum. The attenuation of the soft tissue is that of fat. There does not appear to be any herniation of the inferior rectus muscle. Note the absence of an effusion in the maxillary sinus.
Small fragments of bone are seen within the soft tissue protruding into the right maxillary antrum. The attenuation of the soft tissue is that of fat. There does not appear to be any herniation of the inferior rectus muscle. Note the absence of an effusion in the maxillary sinus.
Note the absence of an effusion in the maxillary sinus.