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.