Title: Traumatic Facial Nerve Injury
1Traumatic Facial Nerve Injury
- Xinyan Huang, MD
- SIU Division of Otolaryngology
- Oct. 6, 2005
2Outline
- Case report
- Anatomy of facial nerve
- Pathophysiology of nerve injury
- Traumatic facial nerve injury
- Classification
- Clinical diagnosis
- Electrophysiologic testing
- Management
3Case 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
4Case 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
5HRCT
6HRCT
7Case GS
Facial nerve exploration
8Case GS
9Case GS
10Case GS
11Case GS
Audiogram 12-15-04 (one mo post injury)
12Case GS
Audiogram 6-1-05 (6 mos later)
13Case GS
- F/U 8 mos
- Facial nerve function improving to HB IV
- Rt hearing improving
- New onset of BPPV Rt
14Case GS
15Case GS
16Anatomy of Facial Nerve
- CN VII
- Spec visc eff
- Facial musculature
- Gen visc eff
- Parasympathetic
- Spec visc aff
- Taste
- Gen soma aff
- Sensation
17Anatomy of Facial Nerve
18Anatomy of Facial Nerve
19Anatomy of Facial Nerve
- Extratemporal portion
- Five branches
- Distal anastomoses
- Frontal and mandibular branches has few
anastomotic interconnection
20Pathophysiology of Nerve Injury
- Sunderland classification
- I Neuropraxia
- II Axonotmesis
- III Neurotmesis
- IV Partial transection
- V Complete transection
21Traumatic Facial Nerve Injury
- Classification
- Site
- Extracranial
- Intratemporal
- Intracanial
- Type of trauma
- Penetrating
- Blunt
- Iatrogenic
22Penetrating 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
23Penetrating trauma
- Intratemporal FN injury
- GSW
- Extensive, multiple site nerve injury
- Immediate, complete paralysis
- HRCT, Angiography
24Penetrating 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
25Blunt trauma
- Temporal Bone Fractures
- Longitudinal vs. Transverse
- Mixed
26Longitudinal 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
27Transverse 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
28Iatrogenic 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
29Clinical 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
30House-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(No Transcript)
32Topognostic Tests
- Lacrimal function
- Schirmers test
- Stapedius reflex
- Taste
- Salivery flow
33Imaging
- HRCT
- MRI
- Angiography / MRA
34Electrophysiologic Testing
35Nerve 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
36Maximal Stimulation Test (MST)
- Maximal stimuli evoke maximal movement
- Subjective comparison of movement
37Electroneurography (ENoG)
- CAP of facial muscle
- Most accurate, qualitative measurement
- Reduction of gt90-95 amplitude correlates with a
poor prognosis for spontaneous recovery
38Electromyography (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
39Electrophysiologic Testing
40Management 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
41Management 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
42Conservative 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
43Surgical Treatment
- Indications
- Immediate vs. Delayed
- Complete vs. Incomplete paralysis
- ENoG criteria
Chang and Cass, Am J Otol 1999, 20 96-114
44Surgical 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
45Surgical 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(No Transcript)
47Management of facial nerve injury due to temporal
bone trauma Chang and Cass, Am J Otol 1999,
20 96-114
48Surgical 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
49Surgical Techniques
50Surgical Techniques
- Nerve repair
- Primary end-to-end anastomosis
- Epineurial
- Perineurial
- Fibrin glue
51Surgical Techniques
- Nerve repair
- Nerve graft interpositional cable graft (prevent
loss of regeneration)
52Surgical Techniques
- Donor nerve grafts
- Greater auricular nerve gap lt10 cm
- Sural nerve gap gt10 cm
53Optimal 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
54Management of Iatrogenic Facial Nerve Injuries
- Injury recognized intraoperatively
- Decompression of proximal and distal end
- Nerve repair, gt50
55Management 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
56Management 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
57Summary
- 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(No Transcript)
59Bibliography
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