Transcript Radiologic Assessment of Orbital Trauma

Radiologic Assessment of
Orbital Trauma
Lani Hoang, MS IV
Radiology
February 23, 2007
Orbital Trauma
• Commonly associated with craniofacial trauma
• Mechanism: MVA, violence, falls
• Predominantly affects young adult males
Assessment of Orbital Trauma
• Check ABC’s
• History of mechanism of injury
• Signs & Symptoms:
Varies but look for s/s suggestive of severe injury, including diplopia,
visual loss, ptosis, lid laceration, subconjunctival hemorrhage,
periorbital ecchymosis or infraorbital anesthesia
• Ophthalmologic examination:
visual acuity, pupil reaction, motility, sensation, globe position, lid
function, integrity of globe and fundoscopy
• Imaging…
Important Considerations during
assessment of Orbital Trauma
• Open Globe
• Retrobulbar hemorrhage or compartment
syndrome
• Foregin Body
• Other Significant Head/Neck Injuries
Indications for further Imaging
•
•
•
•
Significant blunt or penetrating trauma
Suspected Orbital Fractures
Suspected Foreign Bodies
Suspected Open Globe
X-ray vs CT vs MRI????
Imaging
• CT: #1 choice for acute orbital trauma
(Obtain CT with ≤3mm axial cuts & with coronal images)
• MRI: complementary role to CT in the
evaluation of subacute orbital trauma
• Plain film: no primary role
MRI in Subacute Orbital Trauma
• Advantages:
– Images in multiple planes (good for surgical planning)
– Detection of fat herniations into the paranasal sinus
– Distortion, avulsion or herniation of extraocular
muscles are well demonstrated by MR
– MR is best for evaluating chronic orbital soft tissue
trauma and chronic hemorrhage
• Disadvantages:
– Poor detection of focal acute hemorrhage in orbit
– Poor depiction of subtle bony detail
– Contraindicated if metallic foreign body in orbit
Plain x-ray films
• Not recommended for primary
investigation of acute orbital trauma
• May miss 5 to 10% of orbital wall fractures
• Images inferior to CT
• If only X-ray is available, request standard
plain film views of the orbit
(Caldwell, Waters, optic canal, lateral and basal)
Type of Orbital Injury
• Depends on site of impact
• Depends on nature of Injury:
- blunt injury
- pentrating/lacerating/sharp injury
- chemical/burn injury
+/- propagation of injury
• Can result in orbital wall fracture and/or soft
tissue injury to the globe, optic nerve and orbital
soft tissues
Orbital Foreign Body
• CT may miss nonmetallic foreign bodies, such as wood or plastics
• CT should be performed in at least 1.5-mm thin axial cuts to detect
small foreign bodies reliably
• Additional planes of imaging are also helpful, particularly oblique
sagittal views oriented along the optic nerve.
• Intraocular air seen on CT should cause suspicion of penetrating
injury with a potential foreign body
Open Globe
• Globe injury can manifest as penetrating or blunt injury.
• “Flat-tire” appearance of a shrunken and irregular contoured globe is
classic appearance on CT
• A normal-appearing CT scan does not rule out an open globe
Orbital Fracture in Detail
1.
2.
3.
4.
Blow-out Fracture – medial wall and floor
Lateral Wall Fracture
Roof Fracture
Combined Fractures – tripod, nasoorbital
and LeFort I-III
Blow-out Fracture
• Most common orbital fracture
• Mechanism: blunt trauma compresses orbital contents,
raising intraorbital pressure, which then fractures
weakest region of orbit: medial wall and/or floor
Coronal CT demonstrates blow-out fracture involving inferiororbital wall
Lateral Wall Fracture
• Rare since lateral wall is thick and strong
• Mechanism: direct lateral blow, also known as “blow-in”
fracture when displaced toward orbital space
• Commonly associated with diastasis of the
frontozygomatic suture and displacement or fracture of
the zygomatic arch
Coronal CT demonstrating tripod fracture of the lateral wall
Orbital Roof Fracture
• Rare since superior orbital rim is strong & well-supported
• Mechanism: severe blunt trauma (ie MVA)
• Potential communication between the orbit and anterior
cranial fossa - consult neurosurgery
Coronal CT demonstrating orbital roof fracture
Combined Fractures
• Tripod Fracture: force to malar eminence results in
separation of the zygoma from its maxillary, frontal and
temporal attachments
• LeFort Types II & III: symmetric orbitomaxillary fractures
that extend posteriorly, typically involving the pterygoid
plates and pterygomaxillary fossa
• Nasoorbital Fractures: Ant  Post force (dashboard
injury) pushes medial wall posteriorly
LeFort Type II & III Fractures
LeFort II
LeFort III
Other Complications to Consider
• Entrapment of soft tissue
• Intraocular injury – hyphema, angle recession, retinal
detachment, iris disruption, lens dislocation, glaucoma,
cataract, etc…
• Traumatic optic neuropathy
• Enophthalmos of the globe – may occur immediate from
herniation of orbital fat or subacutely after
atrophy/scarring of the soft tissue
• Diplopia – can be caused by direct neuromuscular
damage, entrapment of extraocular muscles or swelling
of orbital contents
• Retrobulbar Hemorrhage
• Arteriovenous fistula
Conclusion
• Orbital trauma commonly occurs in association with
craniofacial trauma
• Perform ophthalmologic exam
• CT is modality of choice for imaging acute orbital trauma
• Consider consultation if suspect ocular or brain injury
References
1.
2.
3.
4.
5.
6.
Green, AD. Maxillofacial trauma. Imaging of Head Trauma. New York, Raven Press, 1994, pp
472-491.
Kousobris, PD & Rosman, DA. Radiologic Evaluation of lacrimal and orbital disease.
Otolaryngolgic clinics of North America 39, 2006.
Mauriello, JA, Gonzalez, CF, Grossman CB et al. Orbital trauma. Diagnostic Imaging in
Ophthalmology. New York, Springer-Verlag, 1986, pp 323-341.
Mazock, JB, Schow, SR, Triplett RG. Evaluation of ocular changes secondary to blowout
fractures. Journal of Oral and Maxillofacial Surgery 62: 1298-1302, 2004.
Pelletier, CR, Jordan, DR, Braga, R, McDonald, H. Assessment of ocular trauma associated
with head and neck injuries. The Journal of Trauma – Injury, Infection & Critical Care 44: 350354, 1998.
Vaughan, DG, Asbury, T, Riordan-Eva, P. General Ophthalmology. Norwalk, Appleton & Lange,
1992.