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Traumatic Facial Nerve Injury

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Title: Traumatic Facial Nerve Injury


1
Traumatic Facial Nerve Injury
  • Xinyan Huang, MD
  • SIU Division of Otolaryngology
  • Oct. 6, 2005

2
Outline
  • Case report
  • Anatomy of facial nerve
  • Pathophysiology of nerve injury
  • Traumatic facial nerve injury
  • Classification
  • Clinical diagnosis
  • Electrophysiologic testing
  • Management

3
Case GS
  • 26 yo AAM, GSW to Rt neck, zone 2/3 entry in Rt
    submandibular region exit to Rt superior
    posterior auricle (11-13-04)
  • Intubated and taken to OR for neck exploration by
    trauma team. Intraoperatively OTO-HN consultation
    for GSW to T-bone
  • Reported Rt CN VII intact, Rt HL

4
Case GS
  • EUA circumferential Fx of EAC, 15 mm lateral to
    annulus, TM intact, no hemotympanum
  • POD 1, Rt facial nerve complete paralysis
  • T-bone HRCT

5
HRCT
6
HRCT
7
Case GS
Facial nerve exploration
8
Case GS
9
Case GS
10
Case GS
11
Case GS
Audiogram 12-15-04 (one mo post injury)
12
Case GS
Audiogram 6-1-05 (6 mos later)
13
Case GS
  • F/U 8 mos
  • Facial nerve function improving to HB IV
  • Rt hearing improving
  • New onset of BPPV Rt

14
Case GS
15
Case GS
16
Anatomy of Facial Nerve
  • CN VII
  • Spec visc eff
  • Facial musculature
  • Gen visc eff
  • Parasympathetic
  • Spec visc aff
  • Taste
  • Gen soma aff
  • Sensation

17
Anatomy of Facial Nerve
18
Anatomy of Facial Nerve
  • Intratemporal portion

19
Anatomy of Facial Nerve
  • Extratemporal portion
  • Five branches
  • Distal anastomoses
  • Frontal and mandibular branches has few
    anastomotic interconnection

20
Pathophysiology of Nerve Injury
  • Sunderland classification
  • I Neuropraxia
  • II Axonotmesis
  • III Neurotmesis
  • IV Partial transection
  • V Complete transection

21
Traumatic Facial Nerve Injury
  • Classification
  • Site
  • Extracranial
  • Intratemporal
  • Intracanial
  • Type of trauma
  • Penetrating
  • Blunt
  • Iatrogenic

22
Penetrating trauma
  • Extracranial FN injury
  • Transections of main trunk, temporozygomatic and
    cervicofacial divisions, should repair
  • Distal to lateral canthus and nasolabial crease
    not require to repair
  • Buccal and zygomatic branches, repair unnecessary

23
Penetrating trauma
  • Intratemporal FN injury
  • GSW
  • Extensive, multiple site nerve injury
  • Immediate, complete paralysis
  • HRCT, Angiography

24
Penetrating trauma
  • Shindo et al (1995)
  • 22/43 (51) FN injuries
  • 15/22 (68) complete paralysis
  • 12/15 (80) surgical exploration
  • Vertical, tympanic and main trunk injury 7/12
    multiple sites injury 9/12 complete transection
  • 7/9 interposition cable graft
  • 4/7 functional recovery to HB III
    2-decompression, 2-nerve graft

25
Blunt trauma
  • Temporal Bone Fractures
  • Longitudinal vs. Transverse
  • Mixed

26
Longitudinal fractures
  • 70-80 of temporal bone fractures
  • Lateral forces along the petrosquamous suture
    line
  • 10-20 facial nerve involvement
  • Delayed onset
  • Perigeniculate segment
  • EAC laceration

27
Transverse fractures
  • 10-20 of temporal bone fractures
  • Forces in the antero- posterior direction
  • 40-50 facial nerve involvement
  • Immediate onset
  • Geniculate, tympanic segments
  • EAC intac

28
Iatrogenic Facial Nerve Injuries
  • Complication of facial plastic, head, neck, and
    otologic surgery
  • 0.6-3.6 otologic cases
  • Green et al (1994a)
  • Mastoidectomy (55)
  • Tympanoplasty (14)
  • Bony exostoses (14)
  • Tympanic segment injury (55)
  • 79 were not identified at the time of surgery

29
Clinical Diagnosis of Facial Paralysis
  • Facial nerve function
  • Exam all branches per facial movements
  • Raise eyebrows
  • Tightly close eyes
  • Wide smile
  • Heavily pucker lips
  • Fully blow cheeks
  • House-Brackmann grading system

30
House-Brackman FN Grading System
  • I Normal Normal facial function
  • II Mild Slight weakness/synkinesis
  • III Moderate Complete eye closure, noticeable
    synkinesis, slight forehead movement
  • IV Moderately severe Symmetry at rest,
    incomplete eye closure, no forehead movement
  • V Severe Assymetry at rest, barely noticeable
    motion
  • IV Total paralysis No facial movement

31
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32
Topognostic Tests
  • Lacrimal function
  • Schirmers test
  • Stapedius reflex
  • Taste
  • Salivery flow

33
Imaging
  • HRCT
  • MRI
  • Angiography / MRA

34
Electrophysiologic Testing
  • NET
  • MST
  • ENoG
  • EMG

35
Nerve Excitability Test (NET)
  • Threshold of excitation
  • Axonal degeneration, NE gradually lost in 3-4
    days
  • gt3.5mA threshold difference suggests severe
    degeneration
  • Useful only during the first 2-3 wks of complete
    paralysis
  • Clinical recovery prior to NE return

36
Maximal Stimulation Test (MST)
  • Maximal stimuli evoke maximal movement
  • Subjective comparison of movement

37
Electroneurography (ENoG)
  • CAP of facial muscle
  • Most accurate, qualitative measurement
  • Reduction of gt90-95 amplitude correlates with a
    poor prognosis for spontaneous recovery

38
Electromyography (EMG)
  • Recording spontaneous and voluntary potential
  • Limited use until 10-14 days
  • Fibrillation potentials degenerating motor unit
  • Polyphasic potentials reinnervation, precede
    clinical recovery, predict a fair to good recovery

39
Electrophysiologic Testing
40
Management of FN Injuries
  • Decision to treat is primarily based on
  • Trauma mechanism penetrating vs. blunt
  • Complete vs. incomplete paralysis
  • Immediate vs. delayed onset
  • Progressive to total paralysis
  • ENoG criteria
  • Conservative vs. surgical treatment

41
Management of facial nerve injury due to temporal
bone trauma Chang and Cass, Am J Otol 1999,
20 96-114
  • Several FN injury results in retrograde axonal
    degeneration
  • Poor prognosis
  • immediate complete paralysis
  • ENoG gt95 degeneration within 14 days
  • Facial nerve decompression
  • 50 excellent functional outcomes
  • True efficacy uncertain
  • Steroids use no data, but expect to benefit

42
Conservative Treatment
  • Normal facial function immediately post injury
    regardless of progression
  • Acute onset of incomplete paralysis without
    progression to complete paralysis
  • Complete paralysis with less than 95
    degeneration within 14 days by ENoG

Chang and Cass, Am J Otol 1999, 20 96-114
43
Surgical Treatment
  • Indications
  • Immediate vs. Delayed
  • Complete vs. Incomplete paralysis
  • ENoG criteria

Chang and Cass, Am J Otol 1999, 20 96-114
44
Surgical Treatment
  • Facial nerve decompression is the main goal of
    early surgical intervention
  • Avoid primary anastomosis or cable graft
  • Suspect location of nerve injury
  • Total facial nerve exploration with adequate
    decompression
  • Surgical Approach
  • Presence or absence of hearing

Chang and Cass, Am J Otol 1999, 20 96-114
45
Surgical Approach
  • Lateral to the geniculate ganglion
  • Transmastoid
  • Medial to the geniculate ganglion
  • No useful hearing
  • Transmastoid-translabyrinthine
  • Intact hearing
  • Transmastoid-transepitympanic
  • Middle Cranial Fossa

Chang and Cass, Am J Otol 1999, 20 96-114
46
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47
Management of facial nerve injury due to temporal
bone trauma Chang and Cass, Am J Otol 1999,
20 96-114
48
Surgical Techniques
  • Decompression
  • Total facial nerve exploration with adequate
    decompression
  • Nerve repair
  • Primary end-to-end anastomosis
  • Tension free
  • Beveling nerve ending
  • Nerve graft
  • Defect gt 1cm

49
Surgical Techniques
  • Decompression

50
Surgical Techniques
  • Nerve repair
  • Primary end-to-end anastomosis
  • Epineurial
  • Perineurial
  • Fibrin glue

51
Surgical Techniques
  • Nerve repair
  • Nerve graft interpositional cable graft (prevent
    loss of regeneration)

52
Surgical Techniques
  • Donor nerve grafts
  • Greater auricular nerve gap lt10 cm
  • Sural nerve gap gt10 cm

53
Optimal timing for FN repair
  • Within 3 days (if ends of transected nerve not
    identified)
  • McCabe (1973) maximal proteosynthetic ability of
    the nerve body at 21 days
  • May (1983) superior results for FN grafting
    within 30 days
  • Modern approaches the earliest possible repair

54
Management of Iatrogenic Facial Nerve Injuries
  • Injury recognized intraoperatively
  • Decompression of proximal and distal end
  • Nerve repair, gt50

55
Management of Iatrogenic Facial Nerve Injuries
  • Injury recognized postoperatively
  • Never let the sun set on a facial nerve injury
  • Immediate complete paralysis surgical
    exploration
  • Delayed paralysis conservative treatment
  • Incomplete steroid
  • Progress to complete ENoG

56
Management of Iatrogenic Facial Nerve Injuries
  • Green et al (1994b)
  • lt50, decompression
  • 75 had HB III or better
  • gt50, nerve repair
  • No patients had better than HB III

57
Summary
  • Traumatic facial paresis and delayed paralysis
    carry good prognosis
  • Clinical and electrodiagnosis assessment to
    determine patients with poor prognosis in order
    to considering surgery
  • Surgery remains a mechanical method of enhancing
    facial nerve regeneration

58
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59
Bibliography
  • Chang CY, Cass SP. Management of facial nerve
    injury due to temporal bone trauma. Am J Otol.
    1999 Jan20(1)96-114.
  • Coker NJ. Management of traumatic injuries to
    the facial nerve. Otolaryngol Clin North Am.
    1991 Feb24(1)215-27.
  • Davis RE, Telischi FF. Traumatic facial nerve
    injuries review of diagnosis and treatment. J
    Craniomaxillofac Trauma. 1995 Fall1(3)30-41.
  • Fisch U. Facial nerve grafting. Otolaryngol
    Clin North Am. 1974 Jun7(2)517-29.
  • Green JD Jr, Shelton C, Brackmann DE. Surgical
    management of iatrogenic facial nerve injuries.
    Otolaryngol Head Neck Surg. 1994b
    Nov111(5)606-10.
  • Green JD Jr, Shelton C, Brackmann DE. Iatrogenic
    facial nerve injury during otologic surgery.
    Laryngoscope. 1994a Aug104(8 Pt 1)922-6.
  • House JW, Brackmann DE. Facial nerve grading
    system. Otolaryngol Head Neck Surg. 1985
    Apr93(2)146-7.
  • May M. Trauma to the facial nerve. Otolaryngol
    Clin North Am. 1983 Aug16(3)661-70.
  • McCabe BF. Injuries to the facial nerve.
    Laryngoscope. 1972 Oct82(10)1891-6.
  • Shindo ML, Fetterman BL, Shih L, Maceri DR, Rice
    DH. Gunshot wounds of the temporal bone a
    rational approach to evaluation and management.
    Otolaryngol Head Neck Surg. 1995 Apr 112(4)
    Apr112(4)533-9.
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