This document discusses the anatomy, etiology, evaluation, and management of iatrogenic facial nerve injury. It describes the segments of the facial nerve and provides surgical landmarks. Common causes of facial nerve palsy include Bell's palsy, trauma, infection, tumors, and iatrogenic injury during procedures like mastoidectomy or parotid surgery. Evaluation involves tests like ENoG and EMG to determine the severity of injury. Management depends on the timing and location of injury, and may involve supportive care, steroids, nerve decompression, repair, grafting, or muscle transposition procedures. The goal is to restore facial muscle function through reinnervation of the nerve.

1. MANAGEMENT OF IATROGENIC FACIAL
NERVE INJURY
Dr. Mamoon Ameen

2. ANATOMY
• Motor root: 7000 axons
• Sensory root (Nervus intermedius / Wrisberg): 3000
axons
• Motor: facial muscles
• Secretomotor: lacrimal, submandibular, sublingual
• Taste: anterior 2/3rd of tongue
• Sensory: Post-aural / concha / ext. auditory canal

3. ANATOMY
SEGMENTS OF FACIAL NERVE
1. Intra-cranial (12 mm): Brain stem to entry into IAC
2. Meatal (10 mm): Within Internal Auditory Canal
3. Labyrinthine (4 mm): Fundus of I.A.C. to Geniculate
gangl.
4. Tympanic (11 mm): Geniculate ganglion to pyramid
5. Mastoid (13 mm): Pyramid to stylomastoid foramen
6. Extra-temporal (15 mm): S.M. foramen to pes
anserinus

4. ANATOMY

5. Anatomy

6. ANATOMY

7. SURGICAL LANDMARKS
Cochleariform process: lies 1 mm inferior to geniculate
ganglion at anterior end of tympanic segment.
Cog: bony ridge hanging from tegmen tympani lies 1
mm above & posterior to cochleariform process.
Incus short process: 2 mm below lies external genu
Lateral Semicircular Canal: 2 mm Antero-Infero-Medial
lies external genu
Oval window: 1 mm above lies external genu

8. SURGICAL LANDMARKS
Tympano-mastoid suture in posterior canal wall: 5-8 mm
medial lies mastoid segment of facial nerve
Digastric ridge in mastoid tip: leads antero-medially to
mastoid segment of facial nerve
Groove between mastoid & bony E.A.C. meatus: bisected
by facial nerve
Tragal pointer: 1 cm antero-infero-medial is facial nv
Root of styloid process: lateral lies facial nerve
Superior border of posterior belly of digastric: superior &
parallel lies facial nerve

9. ETIOLOGY OF FACIAL NERVE PALSY
1. Idiopathic (55%): Bell’s palsy,
2. Temporal bone trauma (25%): Road traffic accident
3. Infection (10%): C.S.O.M., Herpes Zoster oticus
Malignant otitis externa,cholesteatoma
4. Neoplasm (5%): Parotid tumors, Acoustic Neuroma,
Glomus tumors, Malignancy of ear
5. Congenital (4%): Moebius syndrome ,Melkersson Rosenthal syndrome
6. Iatrogenic : Mastoidectomy, Parotid surgery
7. Metabolic (rare): Diabetes mellitus, Hypertension

10. NERVE INJURY
STRUCTURE OF NERVE

11. Nerve injury

12. HOUSE-BRACKMANN FACIAL NERVE GRADING SYSTEM
Nerve injury

13. TOPO-DIAGNOSTIC TESTS
• Audiometry: cochlear nerve function
• Schirmer’s test: Greater Superficial Petrosal Nerve
• Stapedial reflex test: Nerve to stapedius
• Electrogustometry: Chorda tympani
• Submandibular salivary flow: Chorda tympani
• Examination for terminal facial nerve branches

15. ELECTRO-PHYSIOLOGICAL TESTS
• Primary diagnostic modality for surgical decision making
• Estimate the severity of nerve injury ,Prognosis
• Most reliable and objective tests are ENoG and EMG
• Of value only with complete facial paralysis

16. Electro-neuronography
• Measures the amount of intact axons relative to the
healthy side
• Useful between 4 and 21 days of onset of paralysis
• Degeneration > 90% correlated with poor prognosis

17. Electromyography
• Needle electrodes placed within the facial musculature
measures spontaneous and voluntary electrical activity in
the facial muscle
• Assessing the muscle denervation and reenervation
• adjunct to ENoG if surgical intervention is being considered
• Polyphasic action potentials indicate muscle reinnervation
• Fibrillation potentials detected 2 to 3 weeks after injury
indicate significant muscle denervation and poor recover

18. IATROGENIC TRAUMA
• Parotid surgery
• Middle ear and mastoid surgery
• Cerebellopontine angle tumor surgery
• Temporomandibular joint surgery

19. IATROGENIC TRAUMA
Parotid surgery
• Most common surgery with FN injury is parotidectomy
• The likelihood of temporary facial weakness correlates with tumor location deep to the
plane of the facial nerve, previous parotid surgery, previous sialadenitis .
• All parotid surgery is best undertaken with facial nerve monitoring and at the end of the
procedure the main trunk should be stimulated to confirm continuity.
• If there is no response, the nerve and its branches should be closely inspected for areas of
discontinuity.

20. IATROGENIC TRAUMA
Ear surgery
• The incidence of FN palsy 0.6 and 3.6%
• Most common otologic procedures with FN paralysis
--Mastoidectomy – 55%
-- Tympanoplasty – 14%
• Mechanism - direct mechanical injury or heat
generated from drilling
• Most common area of injury – distal tympanic
segment including the 2nd genu, followed by mastoid
segment

21. MANAGEMENT
Recognized at Surgery:
• When the surgeon recognizes that the nerve has been transected, it should be repaired during
the primary surgery
• No return of function should be anticipated sooner than 4 months after transection of the nerve
• If no recovery is noted by the 8th month, the surgeon should consider re-exploring the nerve to
examine the site of repair

22. MANAGEMENT
Recognized immediate Postoperatively:
• Remove the mastoid dressing and ear pack
• Wait for few hours for LA induced weakness to wear off
• Paralysis persist and surgeon
-unsure about integrity of facial nerve ------Re explore as soon as possible
-sure about integrity of facial nerve _______Wait

23. MANAGEMENT
Recognized immediate Postoperatively:
• High dose steroids – prednisolone at 1mg/kg/day x10 days and then taper
• 72 hours – ENoG to assess degree of degeneration
• >90% degeneration – re-explore
• <90% degeneration – monitor
if worsening paralysis occurs re-explore
• If re-exploration is anticipated, assistance from a more experienced surgical colleague is
advisable

24. • Explain the situation to the patient and his family
• Get Ct scan done
• Intraoperative facial nerve stimulation with EMG monitoring is advisable within
the first 3 weeks .

25. MANAGEMENT
Delayed palsy
• delayed palsy is observed a few days after uneventful middle ear surgery with a reported
incidence of 0.9–1.4 %
• The aetiology is unclear, although reactivation of HSV or VZV is postulated as the underlying
mechanism
• Combined use of prednisone and acyclovir should be considered
• Overall prognosis appears to be good

26. MANAGEMENT OF FACIAL NERVE PARALYSIS
Treatment of facial nerve weakness or paralysis may be :
Supportive
Medical
Surgical
Eye care
Combination of all four

27. Selection of the type of management depend on :
• The cause of the facial paralysis
• Type of injury and its location
• The duration of deficit

28. SURGICAL TREATMENT PROTOCOL
• A. Upto 3 weeks:
Nerve decompression or Nerve repair
• B. 3 weeks - 2 years:
Nerve repair or Nerve transposition
• C. >2yrs with fibrillation in EMG
Nerve repair or Nerve transposition
• D. >2yrs with electrical silence in EMG
Muscle transposition/ Eyelid implant/ Facial sling

29. FACIAL NERVE DECOMPRESSION
Decompression : opening the bony canal and nerve sheath to release pressure and reduce compression on nerve
fibers.
• Performed in severe cases when the facial nerve is seriously deteriorating.
• To be effective, the surgery must be performed within 2 weeks of the onset of symptoms.
Most common approach for facial nerve decompression :
• Transmastoid/Middle cranial fossa approach
• – Transmastoid/Translabyrinthine approach

30. DIRECT NERVE REPAIR
• The most effective procedure for reanimating the paralyzed
face.
• Should be done as soon as possible, before significant
muscle degeneration occurs (preferably < 6 months).
• Can be performed with defect < 17 mm
• • If the stumps of the nerve have a neuroma or appear
crushed, the nerve ends should be “freshened” until
normal appearing nerve is evident.
• Goal is tension free, healthy anastomosis

31. DIRECT NERVE REPAIR
• The nerve stumps should be realigned in fascicular groups without tension.
• The perineurium is sutured together followed by the epineurium using 9-0
or 8-0 monofilament nonresorbable nylon suture .
• Recovery of function begins around 4-6 months and can last up to 2 years
following repair

32. NERVE CABLE GRAFTING
• Integrity of proximal and distal nerve stumps and
facial muscles.
• • There is a gap in the facial nerve that cannot be
primarily repaired.
• Graft should be aprox. 25% longer than needed to
allow for a tension free anastomosis•
• The graft must also be placed in a tissue bed that
is free of scar

33. NERVES MOST COMMONLY USED FOR GRAFTING
• Great auricular nerve
• – Usually in surgical field.
• – Can only harvest 7-10cm of this nerve.
• – Loss of sensation to lower auricle
• 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.

34. NERVE TRANSFERS
• Nerve transposition is also known as facial-hypoglossal transfer
• Used in absence of the main trunk of the facial nerve or in cases of intracranial
nerve damage.
• May be performed immediately or up to several years after the injury
• Requires that the patient have an intact distal nerve segment and facial
musculature suitable for reinnervation which determined by EMG .
• Donor site morbidity

35. NERVE TRANSFERS
• Hypoglossal nerve
– Direct hypoglossal-to-facial graft
• Distal branch of facial nerve is attached to hypoglossal
nerve.
• Complications – atrophy of ipsilateral tongue, difficulties
with chewing, speaking, and swallowing.
– Partial hypoglossal-to-facial jump graft
• Uses a nerve cable graft, to connect the distal end of the
facial nerve to a notch in the hypoglossal nerve
• Much fewer complications, but increased recovery time.

36. CROSS-FACIAL NERVE GRAFTING
• This technique employs a nerve graft (typically the sural nerve) that acts
as a conduit for motor axons from the normal side, contralateral facial
nerve.
Options
___ Single contralateral branch to distal nerve anastomosis.
____ Multiple anastomoses from segmental branches to segmental branches
disadvantages :
• Additional donor site in the leg.
• Violating the normal side of the face.
• Two or more suture lines for the axons to cross.
• Long interval until return of function

37. MUSCLE TRANSPOSITION
(DYNAMIC SLING )
• It is employed when there has been long standing paralysis
and the muscles of facial expression have atrophied.
• Allows patients to have a voluntary smile
Local Muscle Transposition
• Most commonly used The temporalis and masseter muscles
• These may be transposed to the upper and lower lips upper
and lower eyelids and the ala

38. MUSCLE TRANSPOSITION
(DYNAMIC SLING )
TEMPORALIS MUSCLE
• Often used for reanimation of the oral commisure
but has been used for orbital Rehabilitation
• Middle 1/3 of muscle is best for transfer

39. MUSCLE TRANSPOSITION
(DYNAMIC SLING )
MASSETER MUSCLE
• Used when temporalis muscle is not available
• May be preferred due to avoidance of large facial
incision
• Vector of pull on oral commisure is more
horizontal than superior/oblique like temporalis

41. MUSCLE TRANSPOSITION
(DYNAMIC SLING )
Free muscle transfer
• A variety of donor muscles have been described.
• These include the gracilis, latissimus dorsi, pectoralis minor.
• The procedure is performed in two stages
• In the first step, a cross-face nerve graft is performed.
• The second stage is the muscle transfer which is done 9 to 12
months later

43. EYE CARE
• Glasses should be worn whenever the patient outside
• If the eye is dry, we can use eye drops (artificial tears ) .
• Taping and Ointment use during sleep
• In cases of long-standing paralysis, it may be necessary to insert a weight ( gold plate)
into the eyelid to close the eye or perform some other procedure to help the eyelid close
(i.e. tarsorrhaphy).

44. Gold Weight Eyelid Implant

45. COMPLICATIONS OF FACIAL NERVE INJURY
1. Incomplete recovery
2. Exposure keratitis.
3. Faulty regeneration of facial nerve
A- Facial tics & spasms
B. Synkinesis
C. Crocodile tear syndrome: gustatory lacrimation
4- psychological and social problems

46. Thank you