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????

(Obtain CT with ≤3mm axial cuts & with coronal images) 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

CT in Acute Orbital Trauma Advantages: Relatively fast No contraindications for metallic foreign body Excellent bony detail to identify fractures Hemorrhages easily identified Visualization of globe injuries, such as lens dislocation Able to monitor unstable patients during CT Disadvantages: May require hyperextension of the head for coronal images (however this may be obtained by reconstructed images)

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

(Caldwell, Waters, optic canal, lateral and basal) 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 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

Coronal CT demonstrating tripod fracture of the lateral 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

Coronal CT demonstrating 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 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: 350-354, 1998. Vaughan, DG, Asbury, T, Riordan-Eva, P. General Ophthalmology. Norwalk, Appleton & Lange, 1992.