Otology Seminar
Facial Nerve Paralysis Induced by Temporal Bone Fracture
R3 黃俊棋 2005/09/07
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Anatomy of facial nerve:
Segment
Cerebellopontine cistern
IAC segment
Labyrinthine segment
Tympanic segment
Mastoid segment
Extratemporal segment
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Location
Brain stem to IAC
In IAC
Fundus of IAC to geniculate ganglion
facial hiatus to pyramidal eminence
Pyramidal process to stylomastoid foramen
Stylomastoid foramen to pes anserinus
Length, mm
15-17
8-10
3-4
8-11
10-14
15-20
Grade system of facial plasy:
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The Detailed Evaluation of Facial Symmetry (DEFS):
total paralysis more paralyzed more normal
face at rest
0
6
14
wrinkling forehead
0
3
7
eye closure
0
9
21
Smiling
0
9
21
Whistling
0
3
7
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Yanagihara facial nerve grading system:
normal symmetry
20
10
30
30
10
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House-Brackmann Classification of Facial Function:
Grade
I. Normal
II. Mild dysfunction
III. Moderate dysfunction
IV. Moderately severe
dysfunction
V. Severe dysfunction
VI. Total paralysis
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Characteristics
Normal facial function in all areas
Gross
 Slight weakness noticeable on close inspection
 May have slight synkinesis
 At rest, normal symmetry and tone
Motion
 Forehead - Moderate-to-good function
 Eye - Complete closure with minimal effort
 Mouth - Slight asymmetry
Gross
 Obvious but not disfiguring difference between the
two sides
 Noticeable but not severe synkinesis, contracture, or
hemifacial spasm
 At rest, normal symmetry and tone
Motion
 Forehead - Slight-to-moderate movement
 Eye - Complete closure with effort
 Mouth - Slightly weak with maximum effort
Gross
 Obvious weakness and/or disfiguring asymmetry
 At rest, normal symmetry and tone
Motion
 Forehead - None
 Eye - Incomplete closure
 Mouth - Asymmetric with maximum effort
Gross
 Only barely perceptible motion
 At rest, asymmetry
Motion
 Forehead - None
 Eye - Incomplete closure
 Mouth - Slight movement
No movement
Type of temporal bone fracture:
 Traditional classification:
 Longitudinal Fracture
70 - 80 %; 10 - 25 % facial palsy; perigeniculate region; compression and
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ischemia; delay type
Transverse fracture:
10-30 %, 30 - 50 % facial palsy, geniculate ganglion and proximal
tympanic segment (small size and lack of fibrous supporting tissue);
avulsion or severed by bony fragments; immediate type
Mixed fracture:
0-20 %
Otic capsule sparing vs. otic capsule violating fracture
Otic capsule violating fracture: 2.5 - 5.6%, 2 times to develop facial paralysis
Yanagihara’s classification:
 Classifications of Nerve Injuries:
Pathology
Conduction block, damming of axoplasm
Transection of the axon with intact endoneurium
Transection of nerve fiber (axon and endoneurium)
inside intact perineurium
Above plus disruption of perineurium (epineurium
remains intact)
complete transection of a nerve
Sunderland
First degree
Second degree
Third degree
Seddon
Neurapraxia
Axonotmesis
Neurotmesis
Fourth degree
Neurotmesis
Fifth degree
Neurotmesis
usually mixed type; degree II to V will cause wallerian degeneration with degeneration and
break up of axoplasma and myelin sheaths and cleared away by macrophage 72 hours later
 Diagnosis:
 Electrical testing:
 distinguish degree I from II - V lesions but cannot distinguish II from V
 rapid wallerian degeneration → neurotmesis; slowly → axonotmesis
 100% wallerian degeneration occurs over 3 to 5 days as the distal axon
slowly degenerates
 Nerve excitability test (NET):
 electrode on the skin over the stylomastoid foramen
 difference ＞ 3.5 mA → progressive degeneration
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 useful only during the first 2 to 3 weeks of complete paralysis
Maximum stimulation test (MST):
 maximal or supramaximal stimuli; but painful
Electroneurography (ENOG) or Evoked electromyography (EEMG):
 transcutaneous bipolar electrode at the stylomastoid foramenwith maximal
or supramaximal stimulation and recorded by electrode in the nasolabial
groove
 average difference: 3%; test-retest errors: 20%; ＞ 30% → meaningful

degeneration ＞ 90% within 6 days or ＞ 95% within 14 days → poor
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Electromyography (EMG):
 Needle electrode into the orbicularis oculi and orbicularis oris muscles
 Voluntarily active facial motor units → good spontaneous recovery
 polyphasic reinnervation potentials in 4 to 6 weeks → good recovery
 fibrillation potentials 10 to 14 days later → degenerating motor units
 Schirmer test
 HRCT
Clinical presentation:
 Immediate onset with degeneration:
 avulsion or severed by bony fragments
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Immediate onset without degeneration:
 compression and ischemia
Delayed onset with degeneration:
 compression and ischemia
 delayed diagnosis of infection
 Delayed onset without degeneration:
 compression and ischemia
Management:
 Steroid
 Surgical exploration
Indication of surgical exploration:
 Immediate, complete facial palsy, degeneration ＞ 90%, without voluntary
motor unit, HRCT showed fracture line; others are controversial
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Fisch: ENoG showed degeneration ＞ 90 % within 6 days of onset of facial
palsy
 90-98 % complete spontaneous recovery in delayed onset cases
Time to exploration:
 McCabe: 72 hours; if impossible, 21th day (nerve cell body is maximally
capable of pushing axoplasmic filaments across the neuronal gap)
 Fisch: 3 weeks later to allow resolution of edema and hematoma
 Chang and Cass: beneficial within 14 days
 Poor return of function 6-18 months later → late exploration and grafting
 Quaranta: 77.7 % good recovery with surgical exploration 2-3 months later
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Ulug: 81 % good recovery with surgical exploration 3 months later
References:
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a case report. J Laryngol Otol. 2005 Feb;119(2):144-7.
Li J, Goldberg G, Munin MC, Wagner A, Zafonte R. Post-traumatic bilateral facial palsy: a case
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Neck Surg. 2001 Jul;125(1):77-84.
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