b
d
c
e
f
103
3 Head and Neck
or hemorrhage, lens subluxation, intraocu-lar foreign bodies, and traumatic cataract.
Orbital hematomas are caused by pen-etrating or blunt orbital trauma. Blood col-lections within the orbit cause increased intraorbital pressure, which, if not recog-nized and treated, can lead to compressive optic nerve injury. Retrobulbar hemato-mas, in particular, have the potential to compress the optic nerve. The clinical pre-sentation is variable, and symptoms related to hematoma formation may not manifest until several days after the acute injury.
CT identifies proptosis, stretching of the optic nerve, and “globe tenting,” in which the angle made by two tangents to the globe that intersect at the optic nerve head is less than 130°. While orbital hemorrhage and hematoma are uncommon, traumatic orbital compartment syndrome can lead to vision loss; in such cases prompt lateral canthotomy and cantholysis may prevent blindness (Fig. 3.9).
◆ Globe and Orbital Soft Tissue Injury
Open globe injury is a consequence of directocular trauma in which the sclera is disruptedand vitreous humor leaks into the adjacentorbital tissue. Although ophthalmoscopy ismore sensitive for detection of small rup-tures, it is not always possible to examine theglobe in acute facial trauma due to periorbit-al soft tissue swelling, and globe rupture isoften identified on CT for face or head injury. The ruptured globe is often small and irregu-lar and can have a flattened contour remi-niscent of a “mushroom” or “flat tire.” Globe rupture may follow either blunt or penetrat-ing trauma. In blunt trauma, it frequently oc-curs at intraocular muscle insertions, wherethe sclera is thinnest.
Some globe ruptures are inapparent on CT. In patients with an apparently intact globe, unilateral posterior lens subluxation (deep anterior chamber) or thickening of the posterior sclera are subtle signs of globe injury. More obvious CT findings in-clude scleral discontinuity, intraocular air
Fig. 3.9a–fa,b Globe rupture with intraocular lens prosthesis extrusion. Extensive right-sided preseptal periorbital hematoma. The right globe is distorted with a mushroom-like appearance. A tiny linear density superolat-eral to the anterior globe is an extruded intraocular lens implant.
c Globe rupture. Globe deformity with posterior attening and reduced volume. The lens is displaced from its normal position.
d Globe rupture with vitreous hemorrhage from drill-bit perforation. Flattened anterior globe, intravitre-ous hemorrhage, and posterior vitreous versus choroidal hemorrhage.
e,f Intraorbital hematoma. Right intraconal and retrobulbar soft tissue stranding with associated mild proptosis.
104Emergency Imaging
a
b
d
c
105
3 Head and Neck
structions of multiplanar data or dedicated temporal bone CT can provide more de-tailed anatomic assessment.
Longitudinal fractures do not typicallyinvolve the otic capsule. Hemorrhage with-in the mastoid air cells and tympanic cavitycauses an immediate conductive hearingloss that resolves over time. Some patientswill have more complicated injuries withossicular dislocation and/or tympanicmembrane disruption. In the case of os-sicular dislocation, conductive hearing lossmay not resolve without surgical repair. Incontrast, fractures that involve the otic cap-sule are usually transversely oriented andare more likely to result in immediate andirreversible sensorineural hearing loss, CSFotorrhea, and facial nerve injury (Fig. 3.10).
◆Temporal Bone Fracture
High-energy impact to the lateral skull can result in fractures through the mas-toid and temporal bone. They are best de-scribed by the fracture orientation relative to the axis of the petrous temporal bone and by involvement of the otic capsule or labyrinth. Patients may have conductive or sensorineural hearing loss, facial paralysis (peripheral seventh-nerve palsy), bruising about the mastoid eminence (Battle sign), or periorbital ecchymosis (raccoon eyes).
Indirect findings are usually evident on noncontrast head CT and include mastoid air cell opacification, fluid within the ex-ternal auditory canal and middle ear, air in the temporomandibular fossa, and in-tracranial air adjacent to the petrous bone. High-resolution axial and coronal recon-
Fig. 3.10a–da,b Otic capsule–violating (transverse) fracture. The fracture is oriented perpendicular to the axis of the petrous temporal bone and crosses the vestibule, the posterior semicircular canal, and the lateral semicir-cular canal. The tympanic cavity and epitympanum are completely opacied.
c,d Otic capsule–sparing (longitudinal) fracture. This fracture is parallel to the axis of the temporal bone and results in incudomalleolar dislocation and intratympanic hematoma. The otic capsule is intact.
106Emergency Imaging
a
b
c
d
e
f
g
107
3 Head and Neck
◆Mandible Fracture
Mandible fractures are classified by ana-tomical location: condyle, coronoid process,subcondyle or ramus, angle, body, symphy-sis/parasymphysis and alveolus. Because themandible is functionally a ring, fractures of-ten occur at two sites or at a single bony sitewith associated temporomandibular joint(TMJ) separation. Frontal impact results insymphyseal fractures, while lateral impact,typical of assault injuries, leads to condy-lar, angle, or body fractures. Facial swelling,dental malocclusion, trismus, and intraoralbleeding are common clinical findings.
Oblique radiographs or panoramic to-mography can identify most mandible fractures. CT, which is usually available in the emergency setting, has the benefit of detecting any associated facial fractures and concomitant intracranial injury. The
cortical margin of the entire mandible should be examined for discontinuity.
“Favorable” fractures are located more posteriorly at the superior mandibular margin and more anteriorly at the inferior margin; these fractures tend to be held in alignment by the pterygoid muscles. “Un-favorable” fractures, which have the oppo-site orientation, are distracted by normal muscular forces. A fracture that enters the root of a tooth is considered an open fracture, and these patients will require antibiotics.
Treatment depends on the location and conformation of the fracture and can consist of either immobilization by maxil-lomandibular fixation, with arch bars