Transcript Oculo-orbital trauma : MDCT finding

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
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
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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
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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.
INTRA-ORBITAL FOREIGN BODIES
• a wood or organic foreign body is suspected if the lowattenuation 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 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.
ORBITAL BONE FRACTURE
ORBITAL ROOF FRACTURE:
• Third area potentially injured.
• It could be associated with osteomeningeal disruption and intracranial
injury.
ORBITAL BONE FRACTURE
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
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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
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
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
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.
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Increased attenuation suggests a hyphema.
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Decreased depth suggests either a corneal laceration or anterior subluxation
of the lens.
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3.
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.
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.