AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Background

Temporal bone trauma usually is the sequela of blunt head injury. Damage to the temporal bone typically requires the application of great force and may cause fracture, hemorrhage, nerve trauma, vascular damage, or disruption of the middle or inner ear structures. Associated intracranial injuries, such as extra-axial hemorrhage, shear (or diffuse axonal injury), and brain contusion, are common.

Potential complications of temporal bone fracture include infection (meningitis), hearing loss, facial (and other cranial) nerve injury, cerebrospinal fluid (CSF) leak/otorrhea, and perilymphatic fistula. Early identification of temporal bone trauma is essential to managing the injury and avoiding complications.

Historically, temporal bone fractures were diagnosed clinically, with imaging playing a minor role in initial evaluation. After the advent of computed tomography (CT) scanning, the high contrast and spatial resolution of this modality provided detailed images of fractures and their complications.

For excellent patient education resources, visit eMedicine's Back, Ribs, Neck, and Head Center. Also, see eMedicine's patient education article Facial Fracture.

Pathophysiology

Longitudinal fractures typically result from trauma to the temporal or parietal region and commonly involve fractures of the temporal squamosa or parietal bone. The line of force runs roughly from lateral to medial. A fracture line may extend through the facial nerve canal, thereby damaging the facial nerve, designated as cranial nerve (CN) VII. Associated injury, such as transection or intraneural hemorrhage, may cause facial nerve paralysis, as can damage from displaced bone fragments. The fracture may also disrupt the ossicular chain, resulting in conductive hearing loss.

Transverse fractures typically result from trauma to the occiput or cranial–cervical junction, with the line of force running roughly anterior to posterior. A fracture passing through the vestibulocochlear apparatus can cause sensorineural hearing loss and equilibrium disorders. Transverse fractures also commonly injure CN VII, because their path often takes them close to the nerve's labyrinthine segment.

Oblique (or mixed) fracture patterns, which extend both longitudinally and transversely, are common, and some case series report that these occur more often than isolated transverse or longitudinal fractures.

Recently, additional classification systems for temporal injuries have been adopted (although not yet universally). One system categorizes fractures according to whether or not they involve the otic capsule. Another classifies them based on whether or not they extend into the petrous region of the temporal bone.

Frequency

United States

Temporal bone fractures commonly result from severe head trauma. Longitudinal fractures (70-90%) are more common than the transverse form (10-30%), although most fractures are oblique (Swartz, 2001).

Mortality/Morbidity

Immediate mortality in the setting of temporal bone fracture typically stems from an associated injury (eg, closed head trauma, abdominal or thoracic injury) caused by blunt trauma; mortality may also result, albeit rarely, from delayed complications of fracture, such as meningitis.

Morbidity from temporal bone fracture is substantial. The most common complications include facial nerve paralysis, hearing loss, and vertigo. The incidence of CN VII damage is higher with transverse fractures than with the longitudinal form (40% vs 20%), but the greater prevalence of longitudinal fractures means that these more often cause facial nerve paralysis (Swartz). When resulting from a longitudinal fracture, this paralysis, possibly caused by displaced fragments, commonly is incomplete and may be delayed. When resulting from a transverse fracture, the paralysis may be immediate and complete. A temporal fracture may also damage the abducens nerve (CN VI).

Hearing loss related to a temporal fracture may be either conductive or sensorineural. Conductive hearing loss usually is associated with longitudinal fracture and ossicular disruption. Sensorineural hearing loss most often occurs with transverse fracture and fracture of the vestibulocochlear apparatus.

Vertigo can result when trauma to the temporal bone damages the membranous labyrinth and vestibule; it can also occur when fracture of the temporal bone extends into the vestibular apparatus or results in a perilymphatic fistula or a CSF leak. Rarely, fractures involving the tympanic cavity and tympanic roof may produce an acquired encephalocele.

A strong correlation exists between fractures involving the petrous bone and CSF leak, facial nerve injury, and hearing loss.

Anatomy

Temporal bone fractures classically are described with reference to the long axis of the petrous bone, being classified as either longitudinal (parallel to the axis) or transverse (perpendicular to the axis). Most, however, are oblique.

The medial aspect of a longitudinal fracture usually is lateral to the carotid canal and terminates near the foramen spinosum. The lateral aspect frequently involves the external auditory canal. The fracture line may also extend through the facial nerve canal or into the middle ear.

In a transverse fracture, the injury begins near the jugular foramen or foramen magnum and extends to the middle cranial fossa. The fracture line commonly passes through the cochlea and vestibular apparatus.

Temporal bone fractures can also be grouped according to whether or not they involve the petrous portion of the temporal bone. For instance, some fractures pass through the tympanic (middle ear), squamous, or mastoid portion of the temporal bone, missing the petrous region. Additionally, temporal bone fractures can be categorized according to whether or not they involve the otic capsule.

Clinical Details

Patients with temporal bone fracture may present acutely (at the time of trauma) with evidence of basilar skull fracture, such as battle sign, raccoon eyes, or hemotympanum. In addition, they may complain of hearing loss or dizziness.

If a temporal bone fracture initially goes unrecognized, delayed presentation may involve CSF otorrhea, hearing loss, or symptoms related to CN VII dysfunction.

Preferred Examination

Patient evaluation should begin with a CT scan of the temporal bone. In addition, most patients should undergo a CT head scan for possible associated intracranial injuries. Although CT scanning may be appropriate for assessing complications, magnetic resonance imaging (MRI) is useful for identifying vestibular hemorrhage, determining the extent of brainstem injury, and demonstrating nerve compression.

Limitations of Techniques

Temporal bone CT scans require additional imaging time and patient cooperation, neither of which may be obtainable in the immediate posttraumatic period. CT scans cannot distinguish between CSF and hemorrhage in the middle ear.

DIFFERENTIALS

Section 3 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Other Problems to be Considered

Facial nerve paralysis
Hearing loss
CSF leak

RADIOGRAPH

Section 4 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

Plain film radiographs of the skull may show opacified mastoid air cells, intracranial air, or, rarely, a lucency (fracture line).

Degree of Confidence

Generally, diagnosis of temporal bone fracture by plain film radiographs is difficult and requires confirmation by CT scanning.

False Positives/Negatives

The false-negative rate with plain film radiographs is high.

CT SCAN

Section 5 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

• A thin-section (1 mm) CT scan can demonstrate a lucency through the temporal bone. Involvement of the middle ear, petrous bone, otic capsule, and facial nerve canal are the primary determinants of prognosis.
• A longitudinal fracture roughly parallels the petrous bone long axis. Involvement of the middle ear, carotid canal, bony labyrinth, and external auditory canal should be noted.
• A transverse fracture is perpendicular to the petrous bone long axis. Involvement of the inner ear structures and facial nerve course should be noted.
• An oblique fracture has both transverse and longitudinal elements.

Degree of Confidence

If adequate CT scanning technique is used, fractures can be diagnosed with a high degree of confidence.

False Positives/Negatives

False-positives may result when normal sutures are misdiagnosed as fracture lines. False-negatives may occur with subtle fractures or when suboptimal technique is utilized (as when the study is performed using section thickness >1.25 mm collimation or without employing a bone algorithm).

MRI

Section 6 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

MRI may demonstrate fluid (high signal on T2-weighted images) in the middle ear and mastoid air cells. T1-weighted images may reveal a bright signal in the labyrinth or middle ear, consistent with hemorrhage.

Degree of Confidence

With regard to depicting temporal bone fractures, MRI has both poor sensitivity and specificity.

NUCLEAR MEDICINE

Section 7 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

Nuclear medicine studies are not a factor in the diagnosis of acute trauma; however, nuclear cisternography may be used as an adjunct to CT scanning in the diagnosis of a persistent, trauma-related CSF leak. In this setting, nuclear cisternography is a sensitive means of confirming the CSF leak but is not accurate in depicting the location.

ANGIOGRAPHY

Section 8 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

Angiography typically is not a factor in the diagnosis or management of temporal bone fracture; however, when the fracture involves the internal carotid artery canal, damage to the carotid artery may occur. Angiography may reveal a filling defect in the lumen, resulting from intimal flap dissection (linear defect) or thrombosis (irregular or round defect). Alternatively, pseudoaneurysm may be present.

INTERVENTION

Section 9 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

No specific therapy techniques are applicable to temporal bone fracture. However, vascular intervention may be used for vascular complications, such as pseudoaneurysm formation, epidural hematoma, and arterial dissection.

Medical/Legal Pitfalls

• Failure to consider the possibility of nonaccidental trauma when evaluating temporal bone fractures

Special Concerns

• When examining pediatric patients, give special consideration to their unique anatomy, to technique, and to etiology. Knowledge of normal skull base synchondroses is essential for avoiding misdiagnosis. When evaluating patients radiologically, particularly pediatric patients, minimize the radiation dose by taking only those images that are absolutely necessary and by reducing the current (milliamperes). In addition, select, if possible, scan angles that avoid exposure of the orbits to radiation. Whenever fracture is seen in the pediatric population, give careful consideration to the possibility of nonaccidental trauma. Although temporal bone fracture is not a typical injury in this setting, investigate further any injury not explained by appropriate history.
• As in all examinations requiring ionizing radiation, CT scanning in the pregnant patient requires double shielding (anterior and posterior) of the abdominopelvic region.

MULTIMEDIA

Section 10 of 11  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Media file 1:  Axial noncontrast CT scan with bone windows reveals a longitudinal temporal bone fracture (arrows).
	View Full Size Image
Media type:  CT

Media file 2:  Axial noncontrast CT scan with bone windows reveals a transverse temporal bone fracture (arrow).
	View Full Size Image
Media type:  CT

Media file 3:  Axial noncontrast CT scan with bone windows demonstrates a complex fracture with a transverse component (arrow) and an oblique component (arrowhead).
	View Full Size Image
Media type:  CT

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

• Aguilar EA 3rd, Yeakley JW, Ghorayeb BY, et al. High resolution CT scan of temporal bone fractures: association of facial nerve paralysis with temporal bone fractures. Head Neck Surg. Jan-Feb 1987;9(3):162-6. [Medline].
• Cannon CR, Jahrsdoerfer RA. Temporal bone fractures. Review of 90 cases. Arch Otolaryngol. May 1983;109(5):285-8. [Medline].
• Goodwin WJ Jr. Temporal bone fractures. Otolaryngol Clin North Am. Aug 1983;16(3):651-9. [Medline].
• Holland BA, Brant-Zawadzki M. High-resolution CT of temporal bone trauma. AJR Am J Roentgenol. Aug 1984;143(2):391-5. [Medline].
• Ishman SL, Friedland DR. Temporal bone fractures: traditional classification and clinical relevance. Laryngoscope. Oct 2004;114(10):1734-41. [Medline].
• Lipkin AF, Bryan RN, Jenkins HA. Pneumolabyrinth after temporal bone fracture: documentation by high- resolution CT. AJNR Am J Neuroradiol. Mar-Apr 1985;6(2):294-5. [Medline].
• Nishiike S, Miyao Y, Gouda S, et al. Brain herniation into the middle ear following temporal bone fracture. Acta Otolaryngol. Aug 2005;125(8):902-5.
• Swartz JD. Temporal bone trauma. Semin Ultrasound CT MR. Jun 2001;22(3):219-28. [Medline].

Article Last Updated: Jan 19, 2007