Temporal Bone Fracture

Posted by e-Medical PPT Thursday, June 7, 2012
Common Exam Findings
Hemotympanum
“Raccoon” sign for ant skull base-Periorbital ecchymosis
Battle Sign-Postauricular ecchymosis

Indications for HRCT
Facial paralysis
CSF/perilymph leak
Suspected vascular injury
Disruption of superior EAC or scutum
Transient or persistent neurological deficits

1,875 lb lateral force for longitudinal fractures
Fractures take path of least resistance
60% considered open
Bloody otorrhea, brain herniation, CSF leak, penetrating wound
8-29% occur bilaterally

Classification
Longitudinal
Parallels long axis of petrous pyramid
70-90%
Caused by lateral force to mastoid or squamous bone
Facial Nerve injury in 10-25%

Transverse
Perpendicular to long axis of petrous pyramid
10-30%
Caused by frontal, parietal, or occipital blow
Facial Nerve injury in 30-50%

Facial nerve injury
In ~7% of temporal bone fractures
 ¼ being complete paralysis
Surgical exploration
 Immediate onset (~27%) vs. Delayed onset (~73%) vs. Delayed Diagnosis
 Penetrating vs. Non-penetrating trauma
 Degree of facial nerve injury
 Presence of infection

Electrodiagnositic testing
Goal – determine whether lesion is partial or complete
Neuropraxia: Transient block of axoplasmic flow (no neural atrophy/damage)
Axonotmesis: damage to nerve axon with preservation of the endoneurium (regrowth)
Neurotmesis:  Complete disruption of the nerve (no chance of organized regrowth)
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