oculo orbital trauma: mdct findings

H . R I A H I , M . B E N M E S S A O U D , O . A Z A I Z , S . G H O M A D I , R . A L L A N I , B . S O U I S S I ,

H . M I Z O U N I , I . T U R K I , E . M E N I FR A D I O L O G Y S E R V I C E , L A R A B T A H O S P I T A L , T U N I S , T U N I S I A

H N 2 0

OCULO ORBITAL TRAUMA:

MDCT FINDINGS

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.

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.

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.

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.

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

RESULTS

Oculo orbital injuries Patients

Orbital floor fracture 31

Medial wall fracture 25

Orbital roof fracture 15

Lateral wall fracture 26

Intra orbital foreign body 13

Retrobulbar contusion, hematoma 16

Intra orbital emphysema 28

Optic nerve contusion 1

Soft tissue herniation and muscle entrapment 17

Lens dislocation 5

RESULTS

Associated fractures with the orbital bone injuries

patients

LEFORT I 2

LEFORT II 7

LEFORT III 1

Maxilla 25

Pterygoid plate 10

Zygomatic bone 21

mandible 4

Temporal bone 3

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

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

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 the flat tire sign, which indicates an open-globe injury.

Unenhanced axial CT scan shows deformity of the globe

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.

OCULAR DETACHMENTS

• Collections of subretinal fluid assume a characteristic V-shaped configuration, with the apex at the optic disk and the extremities at the ora serrata

• Hemorrhagic choroidal detachment may occur.

bilateral retinal hemorrhage.posttraumatic, hemorrhagic

choroidal detachment.

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.

INTRAORBITAL HEMATOMA

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

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

ORBITAL BONE FRACTURE

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

fixed.


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.


ORBITAL ROOF FRACTURE:• Third area potentially injured.• It could be associated with osteomeningeal disruption and

intracranial injury.


LATERAL WALL FRACTURE:• Strongest part of the bony frame, it can still be fractured,

often in combination with other bone lesions.

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.

ORBITAL BONE INJURY

• 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.

ORBITAL BONE INJURY

• 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

ORBITAL BONE INJURY

• 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.

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


• The must common findings of diminished muscle

mobility are:

Muscle impingement by fracture fragments.

Intra conal emphysema

Muscle entrapment

Fat herniation


• 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

OCULAR INJURY

• 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.

• 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.

THE CHECKLIST

1. 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.

2. 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.

3. 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.

THE CHECKLIST

4. 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.

5. 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.

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.

oculo orbital trauma: mdct findings

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