Volume 6, Case 9
Brunhild Halm, MD, PhD
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
This is an 8 year old boy who was playing with his brother who accidentally kicked him in the left side of the face with his knee. The boy developed epistaxis immediately after the injury and he complained of intermittent double vision in his left eye. He did not loose consciousness, but his parents noted increased somnolence and 3 episodes of emesis.
Past medical history is negative.
Exam: VS T36.6, HR 90, RR 16, BP 137/83, oxygen saturation 100% in room air. He is somnolent, but easily arousable. Eyes: Visual acuity 20/25 OU. There is no proptosis. There is ecchymosis and swelling of his left lower eyelid. There is mild left periorbital swelling but no obvious tenderness or step off deformity on palpation. The cornea, lens and anterior chamber are clear. There is no hyphema. Pupils are equal and reactive. There is restricted upward and downward gaze in his left eye, but normal ab/adduction. EOM's are normal in the right eye. Sensation in the distribution of the infraorbital nerve is intact.
TM's clear, no blood. There is blood in his nares. No septal swelling is noted. His pharynx is clear. His neck is nontender with full range of motion. His chest is clear to auscultation. Heart regular without murmurs. Abdomen nontender with active bowel sounds. His speech is normal. Deep tendon reflexes are normal. His strength is normal.
A CT scan of the brain and orbits is obtained.
View CT scan.
The brain is normal. The CT cut shown is taken in the axial projection (i.e., the long axis of his body is perpendicular to the plane of the CT scanner) through the orbits using a "bone window" contrast setting. The black arrow points to the medial wall of the left orbit which is fractured and pushed medially.
Additional coronal CT views are taken of the orbits by hyperextending his neck so that the long axis of his head is closer to being parallel with the plane of the CT scanner. Since axial cuts are parallel with the floor of the orbit, some fractures of the orbital floor are not well visualized. By repositioning the patient so that the CT cuts are perpendicular to the orbital floor, a fracture of the orbital floor can be more accurately visualized.
View coronal CT cut.
These coronal views reveal a fracture of the left orbital floor (black arrow). The white arrow points to the inferior rectus muscle protruding into the maxillary sinus through the orbital floor fracture site. The clinical findings suggest that there may be entrapment of the left inferior rectus muscle, leading to restriction in upward and downward gaze and diplopia when trying to look in these directions. The small depressed fracture of the medial wall of the left orbit with opacification of the left ethmoid air cells is again visible.
Fractures of the orbital floor may be difficult to visualize on an axial CT scan through the orbits since the orbital floor is parallel to the plane of the scan. Fractures are best seen when the fracture is perpendicular or oblique to the plane of the scan. Thus, when an orbital floor fracture is suspected, as in trauma to the orbit, coronal scans of the orbit should be obtained, provided that the patient can be positioned properly.
Orbital wall fractures:
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.
An orbital blow out fracture refers to a fracture of the orbital floor, usually without involvement of the orbital rim. The impacting object typically has a diameter that is larger than that of the orbital opening. Examples include a fist, tennis ball, baseball, snowball or door knob. The mechanism of a blow out fracture is controversial. There are two main theories that are likely: 1) The fracture results from a sudden increase in intraorbital pressure when the globe is being pushed posteriorly. 2) The fracture is the result of "buckling" forces which are transmitted to the orbital bones by transient deformity of the orbital rim.
An aide to the evaluation of children with orbital fractures is the mnemonic HEADER:
Hyphema: Evaluate the child for bleeding in the anterior chamber and for other intraocular injuries.
Emphysema: Orbital emphysema is due to a fracture of the medial wall and/or inferior wall which permits communication between the ethmoid sinus and/or the maxillary sinus with the orbital contents. In order to make the diagnosis of orbital emphysema clinically, the orbit should be palpated for crepitus. Subcutaneous air can be dramatic when the patient blows his/her nose. Patients may notice eye swelling when blowing their nose. Orbital emphysema may be visible on a plain radiograph of the orbit. It is also visible on CT scans.
Epistaxis: A fracture of the medial orbital wall can result in a significant nose bleed.
Anesthesia or hypoaesthesia in the distribution of the second branch of the trigeminal nerve must be suspected in any fracture involving the infraorbital canal. The distribution involves the lower eyelid and the cheek down to the upper lip on the side of the injury.
Diplopia: Double vision has essentially two primary mechanisms: 1) A mechanical entrapment of an eye muscle, most commonly, the inferior rectus muscle, or the inferior oblique muscle. 2) A paralytic component where injury to the third cranial nerve has occurred. The third cranial nerve innervates both the inferior rectus and the inferior oblique muscle. Hemorrhage and edema within the extraocular muscles may also cause transient paresis.
Exophthalmos is secondary to intraorbital hemorrhage and edema which pushes the globe anteriorly. However, a large fracture of the medial wall or orbital floor may result in enophthalmos.
Restriction: Entrapment of extraocular muscles and orbital tissue in the fracture site leads to decreased ocular motility. With orbital floor fractures, the inferior rectus muscle most commonly is entrapped leading to limitation in upward gaze. With medial wall fractures, limited abduction due to medial rectus incarceration may result.
Diagnosis:
CT scanning is highly useful in the assessment of orbital trauma and associated injures to the brain and sinuses. Coronal views (direct or reconstructed) should be requested when orbital trauma is present.
Plain radiographs are not sufficient. They may be helpful in confirming fractures and in the delineation of air-fluid levels in the paranasal sinuses, but they may fail to show the existence and extent of orbital fractures.
Surgical repair of a fractured orbital wall would be indicated in the following instances: 1) Significant enophthalmos. 2) Diplopia in primary gaze or in a functional gaze. 3) Significant limitation of extraocular movements.
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