otorynolaryngology

1. FACIAL NERVE INJURY
Dr Shalina Kaur
ENT HRPZ

2. • The facial nerve is 7th
of 12 paired cranial nerves, it’s a
mixed nerve with motor and sensory roots.
• Emerges from brain stem between pons and the medulla,
controls the muscle of facial expression
• It functions in the conveyance of taste sensations from the
anterior two thirds of the tongue and oral cavity
• It also supplies preganglionic parasympathetic fibre to
several head and neck ganglia

3. Facial nerve origin

4. Facial Nerve Components
– Motor
• Supplies muscles of facial expression
• Stylohyoid muscle
• Posterior belly of digastric
• Stapedius muscle
– Sensory
• Taste to anterior 2/3 of the tongue
• Sensation to part of the TM, the wall of the EAC, postauricular skin, and
concha
– Parasympathetic
• Supplies secretory control to lacrimal gland and some of the
seromucinous glands of the nasal and oral cavities
• Chorda tympani carries parasympathetics to the submandibular and
sublingual glands

5. Nuclei of the facial nerve
• Motor nucleus: in the Pons fibers from it will surround
the abducent nerve nucleus to form the facial colliculus.
• Nucleus solitarious: in the medulla oblongata and
receives the taste fibers
• Superior salivatory nucleus: in the Pons and gives rise
to the parasympathetic fibers

6. Motor root of 7th
nerve
6th nerve nucleus
Motor nucleus of 7th n
Sup. salivary nuceus
Tractus solitarius
Nervus Intermedius
Internal Auditory Meatus
Geniculate Ganglion
Oval Window
Nerve to stapedius
Chorda Tympani
Stylomastoid Foramen
Lacrimal Gland
Sphenopalatine Ganglion
Greater Superficial Petrosal
Nerve
Sublingual Gland
Submandibular Gland
Temporal MB
Zygomatic MB
Buccal MB
Mandibular MB
Cervical MB

8. From pons to internal acoustic meatus
The nerve passes laterally with the vestibulocochlear
nerve (CN VIII) to the internal auditary meatus. At the
bottom of the meatus the nerve enters the facial bony
canal where it runs laterally above the vestibule of inner
ear.
Reaching the medial wall of the middle ear, it bends
sharply backwards above the promontory (forming its
genu) where the genicular ganglion is found
It then arches downwards in the medial wall of the
middle ear to reach the stylomastoid foramen.
INTRACANIAL SEGMENTS

9. Facial Nerve Anatomy
INTRACRANIAL SEGMENT:
•from the brainstem to the internal auditory canal
•15-17 mm
two components:
1. Facial nerve proper (motor):
•arising from facial motor nucleus in pons.
2- Nervus intermedius:
•it is the sensory root of facial lies position between the facial
proper and vestibulcochlear nerve in the pontocerebellar angle.
•Carrying para-sympathetic fibers (from superior salivary
nucleus) and taste fibers ( to the solitary nucleus ) Both join at
the CPA/IAC to form the common facial nerve

10. 1. MEATAL 8-10mm
– Portion of the facial nerve traveling to the meatal foramen of IAC
– Travels in the anterior superior portion of the IAC (7-UP, 8-Down)
»Posterior superior – superior vestibular nerve
»Posterior inferior – inferior vestibular nerve
»Anterior inferior – cochlear nerve
INTRATEMPORAL
SEGMENTS

11. IAC and bill’s bar

12. Facial nerve in IAC
VII facial nerve
NI nervus intermedius
VIIIC cochlear nerve
VIIIvs superior vestibular nerve
VIIIvi inferior vestiblar nerve

13. INTRATEMPORAL
SEGMENTS2. Labyrinthine 4mm
–From fundus to the geniculate ganglion
–Runs in the narrowest portion of the IAC (0.68mm in
diameter)
–Greater superficial petrosal nerve comes off at this point
3. Tympanic11mm
–Runs from geniculate ganglion to the second genu
–It lies above oval window and below lateral SCC
4. Mastoid 13 mm
–From second genu to stylomastoid foramen
–Gives off branches to the stapedius muscle and the chorda
tympani

15. EXTRA TEMPORAL SEGMENT
• exits stylomastoid foramen
– Postauricular nerve - external auricular and occipitofrontalis
muscles
– Branches to the posterior belly of the digastric and stylohyoid
muscles

16. EXTRA TEMPORAL SEGMENT
• Enters parotid gland splitting it into a superficial and
deep lobe
• Pes Anserinus
– Branching point of the extratemporal
segments in the parotid
– To Zanzibar By Motor Car
» Temporal
» Zygomatic
» Buccal
» Marginal mandibular
» Cervical

17. NERVE INJURY:
CLASSIFICATION

18. Components of a Nerve
• Endonerium
– Surrounds each nerve fiber
– Provides endoneural tube for regeneration
– Much poorer prognosis if disrupted
• Perinerium
– Surrounds a group of nerve fibers
– Provides tensile strength
– Protects nerve from infection
– Pressure regulation
• Epinerium
– Surrounds the entire nerve
– Provides nutrition to nerve

19. Sunderland Nerve Injury
Classification

20. Sunderland Nerve Injury
Classification
–Class I (Neuropraxia)
• Conduction block caused by cessation of axoplasmic flow
• What one experiences when their leg “falls asleep”
• Full recovery
–Class II (Axonotmesis)
• Axons are disrupted
• Wallerian degeneration occurs distal to the site of injury
• Endoneural tube still intact
• Full recovery expected
–Class III (Neurotmesis)
• Neural tube is disrupted
• Poor prognosis
• If regeneration occurs, high incidence of synkinesis (abnormal
mass movement of muscles which do not normally contract
together)

21. Sunderland Nerve Injury Classification
• Class IV
• Epineurium remains intact
• Perineurium, endoneurium, and axon
disrupted
• Poor functional outcome with higher risk for
synkinesis
• Class V
• Complete disruption
• Little chance of regeneration
• Risk of neuroma formation

23. BELL’S PALSY
• Temporary facial paralysis caused by damage to the 7 th
cranial nerve (facial nerve)
• Inflamation that causes pressure on the Facial Nerve,
which effect the Facial Muscles.
• Usually only one side of the face is affected and you have
trouble closing your eye and producing tears, controlling
drooling and movement of the mouth

24. FACIAL NERVE TRAUMA
- Second most common cause of FN paralysis
behind Bell’s Palsy
- Represents 15% of all cases of FN paralysis
- Most common cause of traumatic facial
nerve injury is temporal bone fracture

25. Temporal Bone Fracture– 5% of trauma patients sustain a temporal bone fracture
– Three types (Ulrich 1926 classification)
» Longitudinal
• Most common type – 70-80%
• Fracture line parallel to long axis of petrous pyramid
• Secondary to temporoparietal blunt force
• EAC and TM laceration
• Results in facial nerve paralysis in 15-20% of cases
» Transverse
• 10-20% of fractures
• Fracture line perpendicular to long axis of petrous pyramid
• Secondary to frontal or occipital blow, intact EAC
• Results in facial nerve paralysis in 50% of cases
» Mixed
• 10% of temporal bone fractures

26. Longitudinal fracture Transverse fracture
1. Bleeding from external canal due
to laceration of skin and ear drum
2. Fractures involving the bony
portion of external canal
3. Ossicular chain disruption causing
conductive deafness.
4. Facial palsy (rare) 20% usually at
the level of horizontal segment
distal to geniculate ganglion
5. CSF otorrhoea (usually temporary)
6. Sensorineural hearing loss can
occur due to consussion
1. Sensorineural hearing loss due to
damage to 8th cranial nerve
2. Haemotympanum (conductive
deafness)
3. Facial palsy due to damage of
facial nerve
4. Vertigo
5. Labyrinthitis ossificans (this
should be borne in mind before
performing cochlear implant in
these pts)

31. Penetrating Trauma
-Typically results in FN injury in the
extratemporal segments
-Gun shot wounds cause both intratemporal and
extratemporal injuries
• GS wounds to temporal bone result in FN
paralysis in 50% of cases
• Mixture of avulsion and blunt trauma to
different portions of the nerve
• Much worse outcome when comparing GS
related paralysis to TB fracture related
paralysis

32. Iatrogenic Facial nerve Trauma
–Surgical
• Most common is parotidectomy
• Most common otologic procedures with FN paralysis:
– Mastoidectomy – 55%
– Tympanoplasty – 14%
– Exostoses removal – 14%
– Mechanism : direct mechanical injury or heat generated from
drilling
– Most common area of injury - tympanic portion due to its high
incidence of dehiscence in the this area, and its relation to the
surgical field
• Unrecognized injury during surgery in nearly 80% of cases
–Birth trauma
• Forceps delivery with compression of the facial nerve against the
spine

34. Work-up: History
• History
• Mechanism – recent surgery,
facial/head trauma
• Timing – progressive loss of
function or sudden loss
• Transected nerve -> sudden loss
• Intraneural hematoma or
impengiment -> progressive loss
(better prognosis)
• Associated symptoms – hearing
loss ,vertigo

35. Work-up: Physical
• Physical Examination
– full head and neck examination
– Facial asymmetry
– Signs of facial injury: lacerations, hematomas, bruising
– Exam head/scalp for signs of injury to help guide you to
vector of force if head trauma is involved
– Otoscopic examination is a must
• Canal lacerations or step-offs deformity
• Hemotympanum, TM perforation, drainage of blood or
clear fluid from middle ear
• Tuning fork tests help to determine any hearing loss

36. Clinical facial nerve test
• Facial movement:
• Temporal branches:
• Wrinkle forehead
• Elevate eyebrow
• Zygomatic branches:
• Close the eyes
• Mandibular branches:
• Show teeth
• Blow cheek
• Cervical grimacing

37. House-Brackmann Grading System
Grade Characteristics
I. Normal facial function in all areas
II. Mild dysfunction •Slight weakness noticeable on close inspection
•Forehead - Moderate-to-good function
•Eye - Complete closure with minimal effort
•Mouth - Slight asymmetry
III. Moderate dysfunction
-First time you can notice a difference at rest
•Obvious but not disfiguring difference between the two sides
• Forehead - Slight-to-moderate movement
•Eye - Complete closure with maximum effort
•Mouth - Slightly weak with maximum effort
IV. Moderately severe dysfunction
-First time you have incomplete eye closure
-No forehead movement
•Obvious weakness and/or disfiguring asymmetry
• Forehead – No motion
•Eye - Incomplete closure
•Mouth - Asymmetric with maximum effort
V. Severe dysfunction •Only barely perceptible motion
•At rest, asymmetry
•Forehead – No movement
•Eye - Incomplete closure
•Mouth - Slight movement
VI. Total paralysis No movement

38. Work-up: Radiologic Tests
• HRCT scans
• Bony evaluation
• Locate middle ear, mastoid, and temporal
bone pathology
• Gadolinium enhanced MRI
• Rarely done in traumatic facial nerve injury
• better visualisation of soft tissue condition

39. Facial Nerve Testing
• to assess the degree of electrical dysfunction
• Can pinpoint the site of injury
• Helps determine treatment
• Can predict recovery of function – partial
paralysis is a much better prognosis than total
paralysis
• two categories:
–Topographic test
–Electrodiagnostic test

40. Facial Nerve Testing
Topographic test
•Tests function of specific facial nerve branches
•Determine the site of facial nerve injury
•Do not predict potential recovery of function
• Schimer’s test
• Stapedial reflex
• Taste test
• Submandibular salivary flow test

41. Topographic test
• Lesion at nucleus in pons :
• Only motor fx affected
• No taste,lachrymation salivation
disturbance
• no loss of stapedial reflex
• Lesion in CPA/IAM/labyrinthine
segment:
• Impaired lachrymation, stapedial
reflex , taste and salivation
• Lesion between geniculate ganglion
and nerve to stapedius:
• Intact lachrymation
• Impaired stapedial reflex and taste

42. Topographic test
• Lesion between the nerve to
stapedius and chorda tympani:
• Intact lachrymation and
stapedial reflex
• Impaired taste
• Lesion below level of chorda
tympani:
• Pure motor deficit
• Intact lachrymation, stapedial
reflex, salivation and taste

44. Schimer’s test
• The eye is gently dried of excess tears or topical LA
• The filter paper is folded 5 mm from one end
• The folded tip is inserted into the lower lid – at the junction
of the middle and outer thirds of the lower lid – taking care
not to touch the cornea or lashes.
• The patient is asked to keep their eyes closed for the
duration of the test.
• After 5 minutes, the filter paper is removed and the
amount of wetting from the fold is measured.

45. Schimer’s test
• GENERAL INTERPRETATION:
• Normal which is ≥15 mm wetting of the paper
after 5 minutes.
• Mild which is 14-9 mm wetting of the paper after
5 minutes.
• Moderate which is 8-4 mm wetting of the paper
after 5 minutes.
• Severe which is <4 mm wetting of the paper after
5 minutes.
• Normal test suggest lesion after geniculate body
• In facial nerve trauma: compare with normal side,
reduction of >25% is significant(positive
schimmer test)

46. Stapedial reflex
• Part of audiometric
evaluation for all
patient with facial
nerve weakness
• Accomplished at the
time of impedance
testing

47. Stapedial reflex
• Loud sound directed to either ear cause bilateral contraction of the stapedius muscle
• Normally 75-95db above the threshold
• Provide diagnostic information of cochlear, retrocochlear and brainstem pathology
ME(middle ear) IE(Inner ear), VIII(Vestibular Cochlea nerve),
CN(cochlear nucleus) SOC (superior olivary complex ) VII facial
nerve

48. • Both ipsilateral and contralateral are measured
• Normal ipsilateral: intact intergrity of reflex arch of the
tested ear
• Normal contralateral: implies intact afferent and brainstem
pathway of tested ear and intact efferent of contralateral
ear.
• In VII n palsy:
• Absent :the site of injury most likely between geniculate
ganglion and nerve to stapedius
• Present; injury site is distal to nerve to stapedius.

49. Right VII n pathology

50. Cochlear pathology

51. Vestibulocochlear nerve
pathology

52. Severe middle ear pathology

53. Brainstem pathology

54. Testing taste
• sweet, salt, sour and bitter taste are tested along the lateral margin
of anterior 2/3 toward tip oftongue.
• Patient must not retract the tongue in
• Electrogustometry:
• Electrical method
• Small current applied to lateral border of anterior 2/3 of tongue
• Current slowlt increase until patient able to perceive the metallic
taste
• Normal threshold: 1 mA
• 4 mA in chorda tympani involvement

55. Submandibular gland flow
Sialometry
•Under LA: small polythene tube
passed into Wharton’s duct
•Salivation induced by stimulus of 6% citric acid on
the anterior tongue.
•Drops of saliva from each side is mesured and
compared

56. Electrodiagnostic test
• Utilize electrical stimulation to assess nerve
conductivity/function
• Most commonly used today
• Able to demonstrate evidence of degeneration
as early as 3 days after onset
• Common tests:
• Nerve excitabillity test
• Maximal stimulation
• Electroneuronography
• electromyography

57. Nerve Excitability Test (NET)
Compares amount of current required to
illicit minimal muscle contraction - normal
side vs. paralyzed side
•How it is performed:
• A stimulating electrode is applied over the
stylomastoid foramen
• DC current is applied percutaneously
• Face monitored for movement
• The electrode is then repositioned to the
opposite side, and the test is performed again
•A difference of 3.5 mA or greater between
the two sides is considered significant
•Drawback - relies on a visual end point
(subjective)

58. Maximal Stimulation Test (MST)
• Similar to the NET, except it utilizes maximal stimulation
rather than minimal
• Usually >5 mA
• The paralyzed side is compared to the contralateral side
• Not accurate if done within 72 hours
• Comparison rated as equal, slightly decreased,
markedly decreased, or absent
– Equal or slightly decreased response = favorable for complete
recovery
– Markedly decreased or absent response = advanced
degeneration with a poor prognosis
• Drawback – Subjective

59. Electroneurography (ENoG)
• Considered the most accurate of the electrodiagnostic tests
• How it works:
• Bipolar electrodes deliver an impulse to the FN at the stylomastoid
foramen
• Summation potential is recorded by another device placed at
nasolabial region

60. Electroneurography (ENoG)
• Stimulus gradually increased until there is no further increase in the
respond amplitude
• The peak to peak respond amplitude is proportional to number of
intact axons
• The two sides are compared as a percentage of response

61. Electroneurography (ENoG)
• 90% degeneration – surgical decompression should be
performed
• Less than 90% degeneration within 3 weeks predicts 80 -
100% spontaneous recovery
• Disadvantages: discomfort, cost, and test-retest variability

62. Electromyography
• Determines the activity of the muscle itself
• How it works
–Needle electrode is inserted into the muscle, and recordings
are made during rest and voluntary contraction
• Normal = biphasic or triphasic potentials
• Demonstrate the signs of recovery
• 10-21 days post injury - fibrillations
• 6-12 weeks prior to clinical return of facial function –
polyphasic potentials are recordable
• Does not require comparison with normal side
• Not helpful of recent onset injury:
• Showed denervation potential only after 8-10 days

63. FACIAL NERVE TRAUMA:
Surgery

64. General surgical guideline
• Reconstruction:
• When decided for surgery:
• informed consent and preoperative consult are important
• Must inform:
• patient’s face will never be symmetrical or have a normal balance

65. General surgical guideline

66. General surgical guideline
•Blunt Trauma
• Birth trauma and Extratemporal blunt trauma
– Recommend no surgical exploration
– >90% expected to regain normal/near normal recovery
• Complete paralysis following temporal bone fracture
– Likely nerve transection
– Immediate surgical exploration
– 30% need nerve repair
• Partial or delayed loss of function
– Approach similar to iatrogenic partial or delayed loss
– High dose steroids
– ENoG 72 hours
• >90% degeneration – explore
• < 90% degeneration – can monitor and explore at later date
depending on worsening or failure to regenerate

67. Surgery for acute facial nerve
trauma
•Facial nerve decompression:
• Localise site of injury pre operatively
• Full exposure of the nerve from IAC to the stylomastoid foramen
if can’t localize
• Approach:
• Intact - Transmastoid/Middle cranial fossa approach
• Absent – Transmastoid/Translabyrinthine approach
• Diamond burs and copious irrigation is utilized to prevent
thermal injury
• Thin layer of bone overlying the nerve is bluntly removed
• Remove bone fragments and hematoma neurolysis or not to
open the nerve sheath is debatable
– Recommended to drain hematoma if identified

68. Acute vs. Late Decompression -
Controversial
• Quaranta et al (2001) examined results of 9 patients
undergoing late nerve decompression (27-90 days post
injury) who all had >90% degeneration
– 7 patients achieved HB grade 1-2 after 1 year
– 2 achieved HB grade 3
– Concluded that patients may still have a benefit of
decompression up to 3 months out
• Shapira et all (2006) performed a retrospective review looking
at 33 patients who underwent nerve decompression. They
found no significant difference in overall results between
those undergoing early (<30 days post-injury) vs. late (>30
days post-injury) decompression
• Most studies like these have been very small, and lack control
groups.

69. Facial Nerve Repair
• Recovery of function begins around 4-6 months and can last up
to 2 years following repair
• Nerve regrowth occurs at 1mm/day
• Goal is tension free and healthy anastomosis
• 2 weeks following injury -> collagen and scar tissue replace
axons and myelin
– Nerve endings must be excised prior to anastomosis
• Rule is to repair earlier than later - controversial
– After 12-18 months, muscle reinnervation becomes less efficient even
with good neural anastomosis
– Some authors have reported improvement with repairs as far out as
18-36 months
– May and Bienstock recommend repair within 30 days, but other
authors have found superior results if done up to 12 months out

70. Primary Anastomosis
• Best overall results of any surgical
intervention
• Done if defect is less than < 2cm
– Mobilization of the nerve can give nearly 2cm of
length
– With more mobilization comes devascularization
• Endoneurial segments must match -
promotes regeneration
• Ends should be sutured together using
three to four 9-0 or 10-0 monofilament
sutures to bring the epineurium or
perineurium together

71. Grafting and Nerve Transfer
• Performed for defects > 2cm
• Approach is based on availability of proximal nerve
ending
• Success of a nerve graft depends on the following
factors:
• The number of axons remaining in the nerve
• The potential for regeneration of axons
• The status of the facial muscles
• Results in partial or complete loss of donor nerve
function

72. • Great auricular nerve
– Commonly used, usually in surgical field
– Located within an incision made from the mastoid tip to the
angle of the mandible
– Can only harvest 7-10cm of this nerve
– Loss of sensation to lower auricle with use
• Sural nerve
– Located 1 cm posterior to the lateral malleolus
– Can provide 35cm of length
– Very useful in cross facial anastomosis
– Loss of sensation to lateral calf and foot
• Ansa Cervicalis
– only utilized if neck dissection has been performed
• 92-95% of these patients have some return of facial
function
– 72-75% have good results (HB 3 or above)

73. THANK
YOU