Download SMALL GROUP DISCUSSION: CASE A

SMALL GROUP DISCUSSION: CASE A
Learning Objectives:
At the end of this module, the learner must be able to:
1) Describe the orbital wall and ocular adnexae
2) Describe the external topography of the eye globe
3) Describe the internal contents of the eye globe
4) Correlate the position of the eye globe with the other structures of the orbit
5) Describe the various structures transmitted by different fissures and foramina of the orbit
6) Discuss the various sequelae resulting from orbital trauma
7) Discuss the various means of assessing orbital trauma
Case History:
This is the case of a 35-year old male, an employee of a call center in Libis, QC who was seen at The Medical City
Emergency Room after having figured in a vehicular accident. From the patient, it was learned that while speeding
down C-5 on his motorcycle at 3 a.m., he had missed seeing a large pothole and was thrown to the pavement, landing
face first.
Upon eye exam it was found that the vision of both eyes was 20/20, uncorrected. He experienced difficult upon looking
upward and double-vision, as well. On his right eye lids were large contusion and hematomas, while his right eye
showed extensive sub-conjunctival hemorrhage. (Refer to picture below.)
Axial and coronal CT scans were:
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Guide questions:
1) What is the significance of the difficulty of upward gaze?
p.913 – Oculomotor nerve palsy
Superior rectus muscle that is the main muscle of elevation or in the inferior oblique muscle which is the
secondary muscle of elevation. It could also mean damage to the Cranial nerve III which innervates superior rectus and
inferior oblique. However based on the pictures and the plates that were presented it is more likely that the patient had
entrapment of his inferior rectus muscles in the maxillary floor of the orbit that makes it difficult for the patient to look
upward
Complete oculomotor nerve palsy affects most of the ocular muscles, the levator palpebrae superioris, and the
sphincter pupillae. The superior eyelid droops and cannot be raised voluntarily because of the unopposed activity of the
orbicularis oculi (supplied by the facial nerve). The pupil is also fully dilated and non-reactive because of the unopposed
dilator pupillae. The pupil is fully abducted and depressed (‘down and out’) because of the unopposed activity of the
lateral rectus and superior oblique respectively.
2) What is the significance of the double vision or diplopia?
p.913 – Paralysis of the Extraocular muscles
One or more extraocular muscles may be paralyzed by disease in the brainstem or by a head injury, resulting in a
dipopia (double vision). Paralysis of a muscle is apparent by the limitation of movement of the eyeball in the field of
action of the muscle and by the production of two images when one attempts to use the muscle.
3) Which of the orbital walls is weakest?
Strongest
 Formed by the orbital aspect of the frontal structure of the skull, the superior wall of the orbit is considered to
be the strongest yet easily penetrated and thin enough to be translucent.
 The stiffness and length of the orbital walls are proportionally dependent on the anatomical structures which
support and strengthen these walls from the opposite side. The medial wall is therefore strong due to the
support of ethmoid cells. The floor is stronger the less surface there is and the more supported it is by
trabeculae of the maxillar sinus. The strength of the upper and lateral walls are proportional to their thickness.
Weakest
 The weakest of them may have to be the inferior wall and medial walls.
The inferior wall makes up the floor of the orbit, formed by maxilla and
partly by the zygomatic and palatine bones. The medial wall is formed
parallel bones of the ethmoid area, along with some parts of the
lacrimal, sphenoid and frontal aspects. These are considered to be the
weak areas due to being sites for common fractures (blow-out
fractures).
 The orbital floor is on the average the weakest, followed by the
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medial and upper walls. The lateral wall is the stiffest and the
most rigid. ohn H. Harris. The radiology of emergency medicine.
4th ed. Philadelphia: Lippincott
The medial orbital wall, composed primarily of the lamina
orbitalis (lamina papyracea – the paper-thin portion of the
ethmoid bone) is generally considered the weakest part of the orbit. However, the medial orbital wall
is supported by ethmoidal air cell walls (Figure), much in fashion of corrugated cardboard or
Styrofoam. Instead, the groove for the inferior orbital nerve (V-2), which transverses the orbital floor,
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renders the floor the weakest component of the orbit. Consequently, most BOFs (blowout fractures)
involve the orbital floor.
Most common site of Orbital Blowout Fracture
 Pure orbital blowout fracture first occurs at the weakest point of the orbital wall. Although the medial orbital
wall theoretically should be involved more frequently than the orbital floor, the orbital floor has been reported
as the most common site of pure orbital blowout fractures.
Reference:
Jo, V. Rizen, V. Nikolic, B. Banovic. The role of orbital wall morphological properties and their supporting structures in
the etiology of “blow-out” fractures. Surgical and Radiologic Anatomy Volume 11, Number 3 / October, 1989
(http://www.springerlink.com/content/d54pqm20k7166683/)
Jin Sik Burm, Chul Hoon Chung, Suk Joon Oh. Pure orbital blowout fracture: New concepts and importance of medial
orbital blowout fracture Plastic and reconstructive surgery. 1999, vol. 103, pp. 1839-1849
(http://cat.inist.fr/?aModele=afficheN&cpsidt=1838326)
4) What are the structures of the orbital floor?
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The 7 bones of the orbit are the maxilla, zygoma, lacrimal, ethmoid, palatine, sphenoid, and frontal. They
form a cone that supports and protects the globe. The rim of the orbit is thick and strong, whereas the
orbital walls, especially the floor and medial walls, are thin and easily fractured.
The structures of the orbital floor or inferior wall include the maxilla and partly by the zygomatic and
palatine bones. Mainly by the maxilla region, the orbital floor contains the zygomatic process, orbital
surface, infraorbital foramen, frontal process, alveolar process and anterior nasal spine. The zygomatic part
consists of the frontal process, orbital surface, temporal process and zygomaticofacial foramen.
The orbital floor, which is made up of the maxillary bone, overlies the maxillary sinus
Orbital floor – location of more blow out fractures due to inherent weakness of bone overlying maxillary
sinus.
Formed by:
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Maxilla
Palatine
Important structures:
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Infraorbital groove
Transverses floor from lateral to medial
Location of infraorbital nerve which supplies sensation to check and ipsilateral upper alveolus and teeth
The floor is dissected diagonally by the infraorbital groove. The infraorbital nerve, which provides sensation to the
cheek and ipsilateral upper alveolus and teeth, traverses the intraorbital groove and creates a natural "break line" that
alleviates any pressure generated within the globe. Orbital fractures, thus, act as a safety valve against any sudden
intense rise in intraorbital pressure.
The orbital bones are very delicate and their thickness is similar to that of an eggshell. Orbital wall fractures most
often occur in the orbital floor and sometimes in the medial wall, because these are the weakest regions of the bony
orbit. The proximity of the paranasal sinuses, nerves, vessels, extraocular muscles, globe and other orbital structures
predispose them to a wide variety of possible damage from injury producing orbital fractures.
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5) What is the probable mechanism of injury?
Blow-out fracture may result in cases of abrupt trauma to the eye by any object >5cm in diameter. Because the
orbital rim is very strong, the forces of blunt trauma are reflected back, compressing the eye and creating a tremendous
increase in pressure within the orbit.
Since the larger bones which comprise the orbit contain sinuses, the orbital walls are at great risk for fracture;
should the trauma be of sufficient force, these walls can literally "blow out." The medial wall (ethmoid bone) is
occasionally affected. But most commonly, the orbital floor (the superior aspect of the maxillary bone) sustains the
damage. In cases of floor fractures, the eye may partially drop down into the maxillary sinus, causing enophthalmos and
entrapment of the inferior rectus or inferior oblique muscle.
This entrapment leads to a tethering effect, resulting in a limited downgaze ability and, more notably, an
inability toward upgaze in the affected eye. While this situation can be surgically corrected in the early stages, prolonged
entrapment leads to fibrosis of the muscle(s) and permanent motility impairment. Associated medial wall fractures may
induce damage to the medial rectus muscle and/or the lacrimal apparatus, but this is uncommon.
In most cases, these fractures result in orbital emphysema, creating a direct communication between the
ethmoid sinus and the orbit. This produces the feeling of pressure within the orbit when the patient attempts to blow
his/her nose. The greatest risk to consider with medial wall fractures is orbital cellulitis, secondary to sinus infection,
should pathogenic organisms within the sinus invade the post-tarsal eyelid.
Orbital fractures occur when the force generated by blunt trauma exceeds the tolerances of the bony surfaces.
Medial wall fractures can occur either from direct injuries to the face or indirectly as blowout fractures. When the
fracture occurs as a result of a direct injury, it is usually in conjunction with a naso-orbital fracture, which results from
direct application of blunt force to the naso-orbital area. The most frequent cause of these naso-orbital fractures is a
motor vehicle accident that results in the face impacting against the steering wheel or dashboard; additional causes
include blunt trauma from the fist or the elbow. Medial wall blowout fractures are potential sequelae of blunt
periorbital trauma. Common causes for this type of medial wall fracture include fists, elbows, shoe kicks, baseballs, and
tennis balls, all of which have a diameter greater than the orbital rim.
A naso-orbital fracture tends to consist of a comminuted, depressed fracture involving the nasal bones, ethmoid
sinuses, and medial orbital walls. It occurs when a blow of sufficient force is applied to the nasal bridge area. Such blunt
trauma can cause the medial wall to develop a fracture in 1 of 2 ways. First, when the nasal bone fragments are
projected backward, the thin lacrimal bone and lamina papyracea are comminuted easily. The nasal bone and frontal
process of the maxilla may be displaced posteriorly into the ethmoid sinus; as a result, an in-fracturing of the medial
orbital wall into the orbit occurs. Therefore, the compressive force causing nasal fractures is a very important causative
factor of pure medial wall fractures.
With blowout fractures, the medial wall is fractured indirectly. When an external force is applied to the orbital
cavity from an object whose diameter is larger than that of the orbit, the orbital contents are retropulsed and
compressed. The consequent sudden rise in intraorbital pressure is transmitted to the walls of the orbit, which
ultimately leads to fractures of the thin medial wall and/or orbital floor. Theoretically, this mechanism should lead to
more fractures of the medial wall than the floor, since the medial wall is slightly thinner (0.25 mm vs 0.50 mm).
However, it is known that pure blowout fractures most frequently involve the orbital floor. This may be attributed to the
honeycomb structure of the numerous bony septa of the ethmoid sinuses, which support the lamina papyracea, thus
allowing it to withstand the sudden rise in intraorbital hydraulic pressure better than the orbital floor.
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6) What are the methods of assessing and diagnosing orbital fractures?
Orbital fractures happen when one or more bones surrounding the eye are broken. This orbital fracture happens
after some type of injury or a strike to the face, in our case, with the patient hitting the floor face-first in a vehicular
accident. Eye injuries and other damages may be severe depending on the location of the fractures upon examination.
Some symptoms of orbital fractures include swelling of eyelids, bruising around the eye, pain in the eye, double
vision and decreased movement in the affected eyes (with the last two indicated by the pertinent symptoms in the
patient). Some of these, however, may resemble other eye conditions or medical problems, which is why further
examination of the presumed fractures is done.
Initially, physical examinations are made on the patient:
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Inspect the face for asymmetry while looking down from the head of the bed. From this position, it is easiest to
see enophthalmos (sunken eye) or proptosis (protruding eye).
Examine lids for lacerations. If present, consider the possibility of globe penetration.
Palpate bony structures of the supraorbital ridge and frontal bone for step-off fractures.
Examine ocular movements, especially in upward and lateral gaze, and test for diplopia.
Check visual acuity.
Check cornea, using fluorescein if needed, for abrasion (uptake of dye) or lacerations (streaming of fluid in dye).
Check pupils for roundness and reactivity, both direct and consensual.
Examine anterior chamber for presence of blood (flaring on slit-lamp exam) or hyphema (blood layering in
inferior aspect of anterior chamber).
Examine limbus for signs of laceration (teardrop sign) or deformity.
Perform a funduscopic exam to check for blood in the posterior chamber, and examine retina for signs of
detachment.
Evaluate supraorbital, infraorbital, inferior alveolar and mental nerve distributions for anesthesia.
Together with these, an extensive medical History of the patient is sought. With regard to injury:
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Epistaxis or clear fluid running from nares or ears?
Loss of consciousness? If YES, how long?
Any visual problems, such as double or blurred vision?
Any hearing problems, such as decreased acuity or tinnitus?
Malocclusion and is able to bite down without pain?
Areas of numbness or tingling on the face?
(For women) Injury from a partner or if they feel threatened by anyone
(For children) Determine if child abuse is an issue
Specific to the eye:
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Diplopia, especially on lateral and upward gaze, indicating possible entrapment or lens dislocation?
Pain with eye motion indicating possible entrapment or periorbital edema?
Photophobia (iritis)?
Flashes of light (retinal detachment)?
Blurred vision (hyphema, retinal detachment, vitreous hemorrhage)?
Afterwards, physicians might opt to ask the patient to have the following diagnostic tests:
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X-Ray – a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal
tissues, bones, and organs onto film; to be able to identify affected bones in the orbital region
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CT Scan – to produce cross-sectional images of the affected area, having a more detailed picture of the fracture
inside. A diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce
cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows
detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more
detailed than general x-rays.
o This may identify specifically the bones, muscles and even nerves affected
o Imaging method of choice, most especially with coronal and axial views, providing thin cuts (2-3 mm)
focusing on the orbital floor and optic canal
o Thin coronal view may be reconstructed given that the patient is having difficulty positioning upon the
test, caused by severe head and neck trauma
7) What are the possible sequelae of a “blow-out” fracture of the orbit?
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Blow-out fractures occur when a blow to the eye increases pressure in the orbit, causing the weak floor or
lamina papyracea to "blow out" into the maxillary sinus or ethmoid bone. This results in a fracture, though it
often prevents globe rupture and loss of the eye.
Fractures on a medial wall may involve the ethmoidal and sphenoidal sinuses, whereas fractures of the inferior
wall may involve the maxillary sinus. It is also important to note that the superior wall is stronger than the
medial and inferior walls, it is thin enough to be translucent and may be penetrated.
Periorbital fat and extraocular muscles can become entrapped in the fracture, leading to problems of ocular
movement. When the medial wall (lamina papyracea) is fractured, the medial rectus becomes entrapped,
leading to lateral gaze dysfunction.
Blow-out fractures may lead to intraorbital bleeding, which may exert pressure on the eyeball, leading to its
protrusion or exophthalmos. Traumas to the eye may affect adjacent structures and lead to:
o Bleeding into maxillary sinus
o Displacement of maxillary teeth
o Nasal bone fracture, also leading to hemorrhage, blocking of airway and infection that may affect
ophthalmic vein
8) How is a blow-out fracture of the orbit treated?
Specific treatment for orbital fractures will be determined by physician based on:
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age, overall health, and medical history
extent of the injury
location of the fracture
associated double vision that persists or association with eye muscle entrapment
cosmetic concerns
patient’s tolerance for specific medications, procedures, or therapies
other stakeholder’s opinion or preference
Treatment may include:
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A consultation with an ophthalmologist (physician who specializes in comprehensive eye care) may be necessary for
a complete evaluation of the eye.
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Some fractures do not have to be treated immediately. Depending on the injury, time may be allowed for the
swelling and bruising to go away before the fracture is treated.
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The double vision will resolve without treatment in three to four days
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Surgery may be indicated for severe fractures, or if there is involvement of the eye. Surgery may be performed
immediately, or up to several days after the trauma.
Surgical repair is performed if the diplopia is unlikely to resolve spontaneously, there is severe enophthalmus, or the
fracture is so large that the development of enophthalmus is likely.
Surgical repair of a "blowout" is rarely undertaken immediately; it can be safely postponed for up to two weeks, if
necessary, to let the swelling subside. Surgery to place an orbital implant leaves little or no scarring and the recovery
period is usually brief. Hopefully, the surgery will provide a permanent cure, but sometimes it provides only partial relief
from double vision or a sunken eye
Management
All cases of blunt ocular trauma with resultant crepitus or motility restriction warrant orbital imaging studies. Computed
tomography (CT scan) is the procedure of choice. CT is better at imaging the bony structures of the orbit than either
plain skull films (X-ray) or MRI. Obtain both axial and coronal scans.
Should you discover a floor fracture with associated herniation of the orbital contents, consider surgical intervention.
Generally, surgery is only for patients with recent trauma who manifest significant diplopia in primary gaze or downgaze,
or in cases of cosmetically unacceptable enophthalmos. Most oculoplastic specialists will wait 10 to 14 days following
the trauma to allow for resolution of the associated edema and hemorrhage. The treatment consists of surgical
resection of the periosteum and repair of the fracture, utilizing a bone graft or synthetic material such as silicon or
Teflon.
Long-standing entrapment of the extraocular muscles leads to fibrosis and irreversible scarring; intervention to improve
motility after four weeks is typically unsuccessful. Initiate prophylactic antibiotic therapy immediately in the event of
associated medial wall fractures with orbital emphysema, or if there is any suspicion of ethmoid damage. A broad
spectrum oral preparation such as cephalexin or erythromycin (250-500mg QID) may be used for 10 to 14 days. Surgical
repair of the medial wall is unnecessary in uncomplicated ethmoid fractures, since the condition resolves spontaneously
in three to four weeks.
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Cases of orbital blow-out fracture do not constitute an emergency, however, accurate diagnosis and
management of the associated ocular manifestations is paramount.
One test that is very helpful in differentiating muscle entrapment in orbital fracture from other muscle or nerve
complications is the forced duction test. Entrapped muscles will resist forced movements with a forceps or even
a cotton-tipped applicator. Again, this test should ideally be performed after resolution of the orbital swelling.
Check for crepitus by palpating the bony rim of the orbit or lid-small bubbles of air will "pop" when compressed.
For long-standing fractures in which the patient experiences diplopia in downgaze, but is not a surgical
candidate, consider incorporating unilateral prism correction into the patient's reading glasses.
Sources:
Moore and Netter 
https://www.healthsystem.virginia.edu/uvahealth/peds_eye/eyefract.cfm
http://emedicine.medscape.com/article/825772-overview
http://emedicine.medscape.com/article/383739-overview
http://www.tripdatabase.com/spider.html?itemid=825365
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