temporal bone fracture

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CURRENT THERAPYJ Oral Maxillofac Surg 66:513-522, 2008

Temporal Bone Fractures: A Review for the Oral and Maxillofacial SurgeonMichael Gladwell, DMD,* and Christopher Viozzi, DDS, MDFracture of the temporal bone is, by denition, a fracture of the skull base. Even though the oral and maxillofacial surgeon (OMS) may not provide denitive management of temporal bone fractures or their sequelae, a working knowledge of this area is important for any surgeon participating in the care of patients with craniomaxillofacial trauma, because temporal bone fractures are often associated with injuries to other areas of the craniomaxillofacial skeleton and because these fractures are relatively frequent. In many centers, particularly community hospitals, the OMS may be the primary provider of care for facial trauma and will treat patients with clinical or radiographic evidence of temporal bone fractures. Immediate access to other specialists to manage or observe these injuries may not be possible, making the OMS responsible for early evaluation and management. This article briey reviews the epidemiology of temporal bone injuries, as well as the pertinent anatomy, radiographic imaging ndings, and ancillary testing maneuvers. It then presents a more detailed description of the various clinical ndings and the associated management strategies. It concludes with a discussion of the subset of temporal bone fractures involving the temporomandibular joint. 2008 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 66:513-522, 2008

EpidemiologySkull fractures affect 23% to 66% of patients with head trauma,1,2 with 21% of these patients suffering trauma to the skull base.3 Trauma to the skull base is a common component of head injuries, particularly blunt head trauma. In adults, up to 75% of patients with a skull base fracture have a temporal bone fracture as a component of the injury.4-6 Multiple important anatomic structures are affected by these injuries, including the facial nerve, middle and inner ear, and intracranial contents; thus, these are serious injuries, with the potential for signicant long-term sequelae. Risk factors for and causes of temporal bone fractures are similar to those in any patient with head injury: younger age, male gender, motor vehicle accidents, falls,*Resident, Department of Surgery, Division of Oral and Maxillofacial Surgery, Mayo Clinic, Rochester, MN. Consultant, Department of Surgery, Division of Oral and Maxillofacial Surgery, Mayo Clinic, and Assistant Professor of Surgery, Mayo Clinic College of Medicine, Rochester, MN. Address correspondence and reprint requests to Dr Viozzi: Mayo Clinic, Department of Surgery, Division of Oral and Maxillofacial Surgery, 200 First Street SW, Rochester, MN 55905; e-mail: viozzi. Christopher@mayo.edu 2008 American Association of Oral and Maxillofacial Surgeons

recreational injuries, and assaults. Penetrating trauma is also a relatively frequent cause of temporal bone fracture. Other unusual reported causes of temporal bone injury include lightning strikes, chiropractic manipulation, and even ying sh.7-9

AnatomyThe skull base is composed of the occipital bone, 2 temporal bones, the sphenoid bone, and the frontal bone. A skull base fracture may involve only 1, several, or all of these bones. The temporal bone itself is composed of 5 parts: the squamous, petrous, mastoid, and tympanic portions, as well as the styloid process (Fig 1). The squamous portion is smooth and convex; the temporalis muscle attaches to this region. The zygomatic arch projects forward from the inferior part of the squamous portion, giving rise to the articular tubercle just anterior to the glenoid fossa. The fossa is bounded posteriorly by the tympanic portion of the temporal bone, the bony external auditory canal. The pyramidshaped petrous portion of the temporal bone is wedged between the sphenoid and occipital bone at the base of the skull. Through it pass many important structures, including the carotid canal, internal jugular vein, and facial nerve (Fig 2). Fractures of the temporal bone have generally been classied into 2 types, longitudinal and transverse, 513

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FIGURE 1. Temporal bone, lateral view. Gladwell and Viozzi. Temporal Bone Fractures. J Oral Maxillofac Surg 2008.

indicating the relationship of the fracture line to the long axis of the petrous portion of the temporal bone. Longitudinal fractures begin at the squamous portion of the temporal bone, run through the external auditory canal, then turn anteriorly toward the foramen lacerum. The middle ear is spared in this type of fracture, because the fracture traverses lateral or anterior to the otic capsule (Fig 3). Transverse fractures begin from the foramen magnum, run through the otic capsule containing the middle ear structures, then turn anteriorly toward the foramen lacerum (Fig 4). The reported incidence of these fracture patterns is variable. Studies citing the radiographic incidence of each fracture type span a time period during which advances in imaging technology have led to much more detailed radiographic images and thus differences in the frequency of each radiographic diagnosis. Some fractures are not purely of a single type, but rather are a combination of longitudinal and transverse. As a general rule, classic longitudinal fracture accounts for about 80% of cases, with the remaining 20% tranvserse fractures.10-14 Longitudinal fractures are most frequently caused by a lateral blow to the skull in the parietal region. Transverse fractures are more commonly caused by intense blows to the occipital region or by a direct frontal injury. The latter are more frequently serious or fatal injuries. A fracture with signicant comminution or fracture lines running in both longitudinal and transverse directions is termed a mixed fracture.

Because studies have suggested that the traditional classication system may not predict the presence of sequelae, such as facial nerve injury or cerebrospinal uid (CSF) leak, alternatives to the traditional classication scheme have been developed. One alternative scheme that has demonstrated better correlation classies fractures based on whether they are otic capsulesparing or otic capsuleviolating.15 Others have suggested that fracture classications should include more specics regarding fracture location, because of the difculty in describing many fractures as either longitudinal or transverse,10 or should describe fractures in a manner that correlates with the optimal surgical approach to repair the facial nerve.16

Clinical Examination and General FindingsBefore the development and widespread use of computed tomography (CT), temporal bone fractures were diagnosed on the basis of history of head injury accompanied by otorrhea, hemotympanum, and facial paralysis.17 Nonobtunded patients with temporal bone fractures may complain of such symptoms as vertigo, nausea and vomiting, facial muscle weakness, TMJ discomfort or dysfunction, and hearing loss or changes. Evaluating an obtunded patient with a suspected temporal bone fracture is problematic, particularly from the standpoint of facial nerve evaluation.



FIGURE 2. Skull base viewed from above. Gladwell and Viozzi. Temporal Bone Fractures. J Oral Maxillofac Surg 2008.

Clinical signs may include ecchymosis, particulary in the periorbital region due to anterior or middle cranial fossa trauma (raccoon eyes sign), or in the postauricular region due to bleeding from the mastoid veins or postauricular artery (Battles sign). CSF otorrhea or rhinorrhea is a frequent nding, occurring in 20% of temporal bone fractures. Hemotympanum is a very common nding in both fracture patterns, and, if hemorrhage from the external auditory canal (EAC) is severe, can indicate injury to the carotid artery. Facial nerve function should be fully assessed and documented. Sensorineural or conductive hearing loss also is commonly found.

initial workup and treatment of polytrauma patients. It is routinely ordered to rule out life-threatening intracranial hemorrhage. Temporal bone fracture is frequently rst noted during this routine head CT examination. The need for subsequent, more highly detailed CT imaging of the temporal bone should be guided by the subsequent evaluation of the patient; for instance, a patient with conductive hearing loss with no evidence of facial nerve injury, CSF leak, or nystagmus does not necessarily need further CT evaluation.

Other Diagnostic ManeuversFormal facial nerve testing and audiologic testing are additional tests that may be of use in evaluating and treating temporal bone injuries. Audiology is of particular use in a patient with suspected inner ear injury, but can be performed later in a patient with

Imaging StudiesToday, CT scanning is performed routinely to evaluate head-injured patients and is part of the routine



FIGURE 3. Longitudinal fracture traversing external auditory canal but sparing otic capsule. Gladwell and Viozzi. Temporal Bone Fractures. J Oral Maxillofac Surg 2008.

conductive hearing loss, allowing time for the hemotympanum to resolve. Facial nerve testing is indicated in a patient with delayed facial nerve palsy, because this patient may benet from surgical decompression of the facial nerve, although this treatment is controversial. Electroneuronography (ENoG) and nerve excitability testing (NET) can be performed to document the degree of facial nerve dysfunction.

branous labyrinth can be subjected to concussive injuries or direct injury with disruption. Management Conductive hearing loss generally resolves over time (usually within 3 to 4 weeks). Pure hemotympanum generally re