Temporal Bone Fracture
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TEMPORAL BONE FRACTURE
Samson Bd MokuntilYear 4 Medical Student
MM4508 Combined SpecialitiesPosting.
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Anatomy
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Anatomy
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Tympanic part
Small parts laterally
Forms the auditory canal
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Mastoid part
Articulates laterally with the parietal and
occipital bones
Houses major portion of the mastoid air cells
system Which communicates with the nasopharynx
through middle ear and eustachian tube.
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Petrous part
Located medially
Relates to internal carotid artery, the sigmoid
sinus, and the facial and vestibulocochlear
nerves.
It contains the labyrinth with its neural
aperture, the internal auditory canal.
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Trauma
Are most common fractures of the skull base
Classified according to the long axis of the
petrous pyramid.
Classic distribution of fractures arelongitudinal, transverse and mixed.
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T
L
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Pathophysiology
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
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Longitudinal fractures Most common (classically >80% but many are mixed)
Extend from squama into the external auditory canal
All go through middle ear with high incidence of ossicularderangement (Incus & incudostapedial joint most common) andconductive hearing loss
Inner ear usually spared
Facial paralysis in about 15% (proximal tympanic segment just distalto geniculate ganglion)
CSF leak (usually caused by fracture through tegmen or themastoid) Otorrhea: perforation or tear of tympanic membrane
Rhinorrhea: tympanic membrane intact
Injury to carotid artery, jugular vein or sigmoid sinus
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Transverse fractures Exhibit a hemotympanum with an intact tympanic membrane.
Commonly involve the labyrinth Cochlear fracture: sensorineural hearing loss, permanent if cochlear
nerve transected
Labyrinthine fracture: severe vertigo
Facial palsy in 50% - permanent if 7th nerve transected (usually thedistal labyrinthine segment just proximal to geniculate ganglion)
Perilymph fistula (can also result from barotrauma) Disruption of stapes footplate, oval window or round window
Pneumolabyrinth highly suggestive but not always present
Labyrinthine enhancement sometimes present
Injury to carotid artery
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Mixed
This term used to define lesions in which such
predominant lines are not apparent. Severe injuries are characterized by multiple,
irregular breaks involving the middle ear and
inner ear structures in unpredictable
combinations.
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Reference Moore, Keith L.; Dalley, Arthur F; Clinically Oriented
Anatomy, 5th Edition, 2006 Lippincott Williams &
Wilkins. Canalis, Lambert, The Ear Comprehensive Otology;
2000 Lippincott Williams & Wilkins.
http://www.theodora.com/anatomy/the_temporal_bone.html
http://en.wikipedia.org/wiki/File:Gray193.png
http://spinwarp.ucsd.edu/NeuroWeb/Text/ent-
210.htm#anchor163481 Temporal Bone Fracture, Otolarygology Head and Neck
Surgery, University of California.