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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

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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.