OCULO ORBITAL TRAUMA: MDCT FINDINGS

1. OCULO ORBITAL TRAUMA:MDCT FINDINGS H. RIAHI, M. BEN MESSAOUD, O. AZAIZ, S. GHOMADI, R. ALLANI, B. SOUISSI, H. MIZOUNI, I. TURKI, E. MENIF Radiology service, La Rabta Hospital, Tunis, Tunisia HN 20

2. Introduction • Traumatic oculo orbital injury occurs frequently, whether isolated or associated with craniofacial lesion. • Radiological evaluation is often necessary to appropriately manage the trauma-related vision loss and oculo motor disturbance.

3. Introduction • Helical CT is the optimal imaging technique for displaying injuries of the orbit and its contents for determining their severity and for helping surgeon to choose the best course of treatment. • The helical CT has the best sensitivity for bone lesions and allows the search for two major emergency : • transfixing wound of eyeball. • the intraocular foreign body.

4. Objectives • The purpose of this work is • to illustrate the various aspects of imaging lesions in oculo-orbital trauma, • To stress the value of multidetector spiral CT in the diagnosis and assessment of lesions.

5. Materiels and methods • We retrospectively reviewed the CT scans of all patients admitted to our emergency from January 2010 to December 2011 who underwent a GE 64 multi slices CT for cranial and facial trauma, . • A retro-reconstruction on the Orbites; was performed when a routine CT of the head showed periorbital soft tissue edema and/or facial bone fractures in 40 patients.

6. Imaging protocol • Helical acquisition in the axial plane without contrast injection using the following parameters: • In case of suspected vascular trauma such as carotido cavernous fistula or arterial dissection, additional CT angiography may be also performed. • Multiplanar reconstruction (MPR) are displayed in both bone and soft tissue setting using axial,coronal and oblique parasagittal planes along the optic nerve axis

7. results

8. results

9. interpretation process • Note intracranial injury. • Look for foreign body. • Evaluate the bony orbit fractures. • Note any herniation of orbital contents. • Evaluate the anterior chamber. • Evaluate the position of the lens. • Evaluate the posterior segment of the globe. • Look for bleeding or foreign bodies. • Evaluate the ophthalmic veins and optic nerve complex

10. NEUROLOGICAL AND INTRACRANIAL INJURY • During the initial evaluation of orbital trauma, one must always seek intracranial lesions which may be life-threatening: • intracranial hemorrhage • pneumo-encephaly • hydrocephalus • parenchyma edema • intracranial hypertension

11. Open-Globe Injuries • CT findings suggestive of an open-globe injury include • a change in globe contour, • an obvious loss of volume, • the “flat tire” sign, • scleral discontinuity, • intraocular air, • intraocular foreign bodies Unenhanced axial CT scan shows deformity of the globe Unenhanced axial CT scan shows the flat tire sign, which indicates an open-globe injury.

12. Intra-orbital Foreign Bodies • a wood or organic foreign body is suspected if the low-attenuation collection seen on CT images displays a geometric margin.

13. OcularDetachments • Collections of subretinal fluid assume a characteristic V-shaped configuration, with the apex at the optic disk and the extremities at the oraserrata • Hemorrhagic choroidaldetachment may occur. posttraumatic, hemorrhagic choroidaldetachment. bilateral retinal hemorrhage.

14. Injuries to the Lens • After a complete disruption, the lens may dislocate posteriorly or, less commonly, anteriorly. Unenhanced axial CT scan: a partially dislocated lens.

15. Intraorbitalhematoma • It should be reported because there is a risk of compression of the globe leading to ocular hypertension and vascular and nerve compression.

16. INTRAORBITAL EMPHYSEMA • Occurs especially when bone fracture framework allows the intrusion of air from the para-nasal sinuses into the orbit • It can be responsable of intra-orbital hypertension

17. Orbital bone fracture MEDIAL WALL FRACTURE: • Area of maximum orbital bone fragility. • The incarceration of the medial rectus and superior oblique is rarely fixed.

18. Orbital bone fracture ORBITAL FLOOR FRACTURE: • The orbital floor fracture is the second site after the orbital plate of the ethmoid. • There is a risk of soft tissue herniation and muscle entrapment.

19. Orbital bone fracture ORBITAL ROOF FRACTURE: • Third area potentially injured. • It could be associated with osteomeningeal disruption and intracranial injury.

20. Orbital bone fracture LATERAL WALL FRACTURE: • Strongest part of the bony frame, it can still be fractured, often in combination with other bone lesions.

21. DISCUSSION • Before any interpretation of orbital injuries, lesions of the central nervous system compromising vital prognosis have to be identified. • Helical CT is the technique of choice for displaying bone fragmentation, the degree of dislocation and rotation and skull base involvement.

22. Orbital boneinjury • An imaging study should provide a detailed description of their spatial relationships to the oculomotor muscles and optic nerve • In orbital « blow out » fractures, orbital contents herniate into the maxilla sinuses, with the result that the inferior rectus may become trapped at the fracture site.

23. Orbital boneinjury • The thinner bones of the orbit are involved, including the orbital plates of the ethmoid and orbital floor. • Such lesions are especially at high risk of • muscle impingement, • muscle entrapment • intra orbital emphysema

24. Orbital boneinjury • Fractures of the roof and lateral walls of orbit, which are more resistant, are observed in craniofacial trauma as LEFORT III. • Intra orbital bone fragments are often associated and may cause • compressive hematoma, • emphysema, • muscle impingement • optic nerve compression.

25. Extra ocular and intra orbital injury • It involves the association with orbital bone injury. • orbital muscles, • fat • optic nerve • Helical CT with coronal reconstructions may show muscle entrapment through a small orbital wall disruption

26. Extra ocular and intra orbital injury • The must common findings of diminished muscle mobility are: • Muscle impingement by fracture fragments. • Intra conal emphysema • Muscle entrapment • Fat herniation

27. Extra ocular and intra orbital injury • CT can determine whether an intraorbital foreign body is present and if so its nature and position • Helical CT may also provide indirect evidence of optic nerve contusion when a fracture of of the optic foramen is detected

28. Ocularinjury • The sensitivity of helical CT in detecting 0.5mm metallic bodies on 3mm CT images can reach 100%. • If foreign body is not visible, indirect signs on CT may be helpful such as: • Intra ocular air. • Scleral deformity. • Volume loss of the globe. • Lens absence.

29. Intraocular hemorrhage is common and may appear as hyperdensity of the vitreous and choroidal hematoma. • The position of lens has to be comparatively studied. • Subluxation and dislocation are easily discernable.

30. THE Checklist • Evaluate the bony orbit for fractures, and note any herniations of orbital contents. Pay particular attention to the orbital apex, where even a tiny fracture may be an indication for emergent surgery. • Evaluate the anterior chamber. • Increased attenuation suggests a hyphema. • Decreased depth suggests either a corneal laceration or anterior subluxation of the lens. • Increased depth is associated with open-globe injuries. • Evaluate the position of the lens. Remember that the lens may be displaced, either anteriorly or posteriorly, and that it may be either completely or partially dislocated.

31. THE Checklist • Evaluate the posterior segment of the globe. Look for bleeds or abnormal fluid collections. Try to localize the fluid collections, remembering the characteristic shape of fluid collections in a retinal or choroidal detachment. Also, evaluate for radiopaque or radiolucent foreign bodies. Remember that wooden foreign bodies can mimic air on CT scans. • Evaluate the ophthalmic veins and the optic nerve complex. If the ophthalmic veins are dilated, look for other signs of carotid cavernous fistula. The optic nerve may be transected, particularly in penetrating traumas. In blunt traumas, the key area to evaluate is the orbital apex.

32. Conclusion • The overwhelming majority of patients with decreased visual acuity or reduced extra ocular muscle motility consequent to trauma had abnormalities demonstrated by orbital CT. Hence, CT examinations should play a major role in the evaluation of the intra orbital contents in patients with orbital trauma.