Facial nerve injury and reanimation : A lecture at the board training

2. Embriology of facial nerve
• The facial nerve is the 7th cranial
nerve .
• formation of facial nerve began at
the 3rd week of embryonic life from
the 2nd pharangeal arch .
• The complexity of the nerve's
course, its branching patterns, and
its anatomic relationships are
completed at the end of 3rd month
of prenatal life.
• During this period, the muscles of
facial expression also differentiate,
become functional, and actively
contract.

3. Anatomy of facial nerve
• emerges from the brainstem
between the pons and the medulla
• controls the muscles of facial
expression, and taste sensations
from the anterior two-thirds of the
tongue .
• also supplies preganglionic
parasympathetic fibers to several
head and neck ganglia .
• The motor part of the facial nerve
arises from the facial nerve nucleus
in the pons while the sensory part
of the facial nerve arises from the
nervus intermedius.

4. Intracranial part
• The portion of the nerve from the
brainstem to the internal auditory
canal
• Carries preganglionic
parasympathetic fibers and special
afferent sensory fibers

5. (( Intra temporal part ))
 Important branches of facial
nerve in this part :
1. Greater superfacial petrosal
nerve :
 Carries parasympathetic fibers
to lacrimal gland and glands of
the nose and palate.
2. Nerve to Stapedius muscle
3. Chorda tympani
 carries parasympathetics to the
submandibular and sublingual
glands & Taste to anterior 2/3 of
the tongue .

6. Extracranial part
 Main trunk ( 15 – 20 mm) :
1. Give branches to the posterior belly
of the digastric and stylohyoid
muscles.
2. Postauricular to occipitofrontalis
muscles
 Branching of the extracranial segments
in the parotid gland that splitting it into
a superficial and deep lobe :
• Temporal
• Zygomatic
• Buccal
• Marginal mandibular
• Cervical

7. Component of nerve
• Endoneurium :
• Surrounds each nerve fiber
• Provides endoneural tube for
regeneration
• Perineurium :
• Surrounds a group of nerve fibers
(fascicle).
• Provide tensile srtength
• Protect nerve from infection
• Epineurium :
• Surrounds the entire nerve
• Provides nutrition to the nerve

8. Sunderland Nerve Injury Classification
 Class I (Neuropraxia)
• Axon remain intact
• Conduction block caused by cessation of axoplasmic flow
• Full recovery
 Class II (Axonotmesis)
• Axons are disrupted
• Endoneural tube still intact
• Full recovery expected
 Class III (Neurotmesis)
• Neural tube is disrupted
• Poor prognosis
• If regeneration occurs, high incidence of synkinesis (involuntary
movement of muscles associated with voluntary movement other
muscles )

9. 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

11. Causes of Facial nerve paralysis
supranuclear lesions :
• Congenital abnormalities, stroke ,
malignancies, trauma , vascular conditions
and other causes .
• only lower part of the opposite side of the
face is paralyzed.
• The upper part with the frontalis and
orbicularis oculi escapes due to bilateral
representation in the cerebral cortex.
infranuclear lesions :
• Malignancy (parotid gland as well as
tumors of adjacent structures) , trauma,
infections, Bell’s palsy, osteopetrosis and
iatrogenic causes .
• the whole of the face of the same side gets
paralyzed.

13. Signs and symptoms of facial nerve paralysis
• The symptoms according to the level
of injury of facial nerve.
 At internal auditory meatus;
 loss of lacrimation, stapedial reflex,
taste from most of anterior two-third of
tongue, lack of salivation and paralysis
of muscles of facial expression.
 Below geniculate ganglion;
 loss of stapedial reflex, taste from
anterior two third of tongue, lack of
salivation and paralayis of facial
expression muscles.
 Region below stylomastoid foramen
paralysis of facial expression muscles.

15. House-Brackmann Grading System
used for clinical assessment of patient
with facial nerve paralysis.

16. 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
 Obvious asymmetry.
• Forehead - Slight-to-moderate movement
• Eye - Complete closure with maximum effort
• Mouth - Slightly weak with maximum effort
IV.
Moderately
severe dysfunction
• Obvious weakness and/or disfiguring asymmetry
• Forehead – No motion
• Eye - Incomplete closure
• Mouth - Asymmetric with maximum effort
V.
Severe dysfunction
 Only minimal motion seen.
• At rest, asymmetry
• Forehead – No movement
• Eye - Incomplete closure
• Mouth - Slight movement
VI. Total paralysis  No movement

17. Grade Definition
I Normal
II Very mild weakness
III Obvious weakness,
asymmetry of mouth
Complete eye closure
IV Obvious weakness,
asymmetry of mouth
Incomplete eye closure
V Very slight movement only
VI No movement at all

18. Preoperative evaluation
• History : focusing on the onset and duration of weakness.
• complete physical exam of the head and neck including a
cranial nerve examination .
• The muscles of facial expression are evaluated for
symmetry and function—both statically and dynamically.
• electrical testing is performed to determine the
physiological status of the facial nerve branches and the
muscles of the face.
(EMG & ENG)

19. electrical testing of facial nerve
 ELECTRONEUROGRAPHY (ENOG)
• measure of the amount of intact axons relative
to the healthy side .
• used to determine prognosis pre-operatively
• Degeneration greater than 90% is correlated
with a poor prognosis .
 ELECTROMYOGRAPHY (EMG)
• Electromyography is often used as an adjunct to
ENOG
• EMG can be used to identify false positive ENOG
results
 NERVE EXCITABILITY TEST (NET)
• determine prognosis for facial nerve
recovery
• A threshold difference of greater than 3.5
mAmps correlates with a poor prognosis.

20. Rehabilitation of the Paralyzed Face
 Goals
– Functional
• EYE PROTECTION
• Oral competence
– Cosmetic
• Symmetry at rest
• Volitional movement
– Facial expressions

21. MANAGEMENT of facial nerve paralysis
Treatment of facial nerve weakness or paralysis may be :
 supportive
 medical
 surgical
 eye care
 combination of all four .
 Selection of the type of management depend on :
• The cause of the facial paralysis
• Type of injury and its location
• The duration of deficit

22. Medical Treatment
• Medical treatment is instituted to decrease the swelling.
• It often involves the use of steroids. This treatment may be continued until the
nerve shows sign of recovery.
 Prednisolone 60-80 mg/day in divided doses intial 4-5 days,then taper over next
7-10 days.
– Decreases the possibility of permanent paralysis .
– From swelling of facial nerve in facial canal .
– Decreases the severe pain .
 Antiviral may be effective in some cases of paralysis (bells palsy).
• Acyclovir 400mg 5 times a day –10 days
• Valacyclovir 1000mg /day 5-7 days .

23. Surgical Reanimation Techniques
Broadly classified into:
I . Neural methods:
• Facial Nerve Decompression
• Micro-neurological surgery to re-suture the damaged nerve.
• Nerve graft (to overcome gaps)
• Cross-Facial Nerve Grafting
• Nerve Transfers
• Hypoglossal to facial
• Spinal accessory to facial
• Phrenic to facial
II . Musculofascial transpositions:
• Move new muscles and nerves into the face to take the place of the injured facial nerve.
III . Facial plastic procedures.
IV. Prosthetics.

24. OTHER CLASSIFICATION
• Static
– Slings
– Gold weight
– Tarsorrhaphy
– Lower lid shortening
• Dynamic
– Nerve grafting
– Muscle transfer
• Regional
• Free flap

25. Facial Nerve Decompression
• Performed in severe cases when the facial nerve is seriously
deteriorating.
• Patients are at risk of permanent paralysis and have a poor
prognosis without aggressive intervention.
• To be effective, the surgery must be performed within 2 weeks of
the onset of symptoms.
• Most common approach for facial nerve decompression :
 Retrosigmoid facial nerve decompression
 Translabyrinthine facial nerve decompression

27. 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).
• If the stumps of the nerve have a neuroma or
appear crushed, the nerve ends should be
“freshened” until normal appearing nerve is
evident.
• 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 .

28. Direct nerve repair
 More recently, tissue engineering has provided nerve conduits, which function as
guides for axonal growth.
 Depending on the materials used for their construction, they can be classified as
natural, when based on laminin, collagen or even vessels and decellularized
nerves, or artificial, usually made of polymers .
 The major limitation for use of nerve conduits is the low rate of axonal growth,
which may not yield full repair within the available time and chronic inflammtion
which should be removed after period of time
 Studies have shown that the conduits are effective in promoting repair of nerve
gaps measuring up to 3 cm, while nerve autografts are required for bridging of
larger distances
 Recently,Wakao et al. used biodegredable collagen nerve conduits filled with
autologous bone marrow MSC differentiated into Schwann cells to promote
repair

29. Nerve Grafting
• Integrity of proximal and distal
nerve stumps and facial muscles.
• There is a gap in the facial nerve
that cannot be primarily repaired.
• The length of the graft should be
about 20% longer than the gap.
• The graft must also be placed in a
tissue bed that is free of scar.

30. 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 &
skin over the angle.
• 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.

31. Nerve transfers
• Nerve transposition is also known as facial-hypoglossal
transfer
• This technique is employed when direct repair or grafting is
not possible.
• This may be due to the 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 .
• Facial appearance may be nearly normal at rest. There will
be some persistent weakness of the face at movement .

32. 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.

34. 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

35. Static Suspension Procedures
 It is used for suspension of the forehead , eyelids, nares, oral commissure,
upper and lower lip.
 used to achieve symmetry at rest .
 They provide no dynamic return of function.
 It can be used alone or in combination with muscle transfers.
• Autologous materials
• Tensor fasciae lata.
• Temporalis fascia.
• Synthetic materials
• Silastic rods.
• Gore-Tex.
• Dynamic transfers .
 Local Muscle Transposition
 Free functioning muscle transfer.

37. Static slings before and after the operation

38. Dynamic transfers
 Local Muscle Transposition
 Free functioning muscle transfer.

39. Dynamic transfers
• Local Muscle Transposition
• It is employed when there has been
long standing paralysis and the
muscles of facial expression have
atrophied.
• The masseter and temporalis muscles
are the two most commonly used.
• can activate it by clenching the teeth.
• These may be transposed to the upper
and lower eyelids and the ala and the
upper and lower lips.

41. Dynamic transfers
• Free muscle transfer
• It is appropriate for those with
intracranial or congenital causes of
facial paralysis.
• A variety of donor muscles have been
described. These include the gracilis,
latissimus dorsi, pectoralis minor.
• The procedure is performed in two
steps ;
• 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.

44. Eye Care
• Glasses should be worn whenever the patient outside .
• Contact lenses should not be worn in this situation .
• If the eye is dry, we can use eye drops (artificial tears ) .
• Ointment may be prescribed for use at bedtime .
• The best protection for night/sleep hours is to place a clear eye guard
over the eye. This can be secured in place with tape.
• Any eye problems or irritation which does not quickly pass should
warrant consultation with ophthalmologist as soon as possible.
• If facial weakness is anticipated following surgery, a silk thread is
sometimes placed in the lid to help close it. When lid closure is adequate
this easily removed.
• In some 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).

46. Lid Gold Weights
46

47. Miniature Micro Chip Technology and Artificial
Muscle Implant
47

48. The Nose
• The collapse of the nasal sidewall can be
corrected either from the outside or the
inside of the nose.
• Outside techniques involve placing strips
of suspension material from the
cheekbone, under the skin, to the nasal
sidewall, and suspending the nasal
sidewall in its anatomic position.
• To widen the nasal cavity from the inside,
small cartilage grafts can be inserted
into the framework of the nose.
48

49. Adjunctive Procedures
 Soft-tissue procedures to improve symmetry
o Rhytidectomy
o Excision of redundant intraoral mucosa.
o Blepharoplasty
o Brow lift
 Procedures for drooling
o Wilkie procedure
o Submandibular gland resection with parotid duct ligation
 Modification of normal side to improve symmetry:
o Neurectomy.
o Myectomy.

51. Modern studies
about
facial nerve reanimation

52. Daily Facial stimulation to Improve Recovery after Facial Nerve
Repair in rats
By Robin W. Lindsay and colleagues , in 2010
• The slow rate of facial nerve regeneration following
certain injury and even surgical management of
paralysed facial nerve can lead to degeneration of the
motor end organ and permanent loss of function.
• A variety of pharmacologic agents have been shown to
improve motor nerve regeneration in animals, including
; angiotensin II, nitric oxide,and brain-derived
neurotropic factor but due to it is adverse effects and
the difficulties with drug delivery and
bioavailability,none of these drugs is in clinical use.
• So this study came to improves recovery of facial nerve
after transection and repair depending on daily
mechanical whisker stimulation via either protraction or
retraction .
 Full recovery occure 4 months after complete
nerve transection.

53. Peripheral Nerve Repair with Cultured Schwann Cells
Maria Carolina O. Rodrigues and her colleages
26 January 2012
• The bone marrow is a rich source of mesenchymal cells, which can be differentiated
in vitro into Schwann cells and subsequently engrafted into the damaged nerve.
• Experimental studies provide evidence of functional, histological, and
electromyographical improvement following transplantation of bone-marrow-
derived mesenchymal cells in animal models of peripheral nerve injury which
can be diffrentiated in to Schwann cells that have a central role in nerve repair,
• Activated Schwann cells produce collagen and laminin, creating a tunnel of
extracellular matrix, and express cell adhesion molecules and
receptors, including IL-1, N-cadherin, gamma integrins, and the
neural cell adhesion molecule
• other alternative sources of mesenchymal stromal cells are :
• the adipose tissue and skin
• Also, the bulge area of the hair and whisker follicles

54. Stem cells could help regenerate facial nerve
José Tadeu Arantes . August 14, 2013
• Nerve regeneration depends critically on Schwann cell structure which provide support
and growth factors that is essential for nerve growth . The problem is that Schwann
cells are scarce in an organism. So the ulternative is the use of stem cells to bridge this
gap
• The study was conducted in animals (rats) subjected to neurotmesis .The animals were split
into four groups. In the first, the two remaining parts of the selected nerve were connected
by a hollow silicon tube; in the second, the tube was filled with an acellular gel; in the third, it
was filled with undifferentiated stem cells; and finally, in the fourth, in was filled with
Schwann-like differentiated stem cells .
• The result was that all animals that received stem cells (undifferentiated or differentiated)
had a much more significant improvement than those that received an empty tube or a tube
filled with gel. Which confirme the rule of stem cells in nerve regeneration .
• the experiment brought one surprise: undifferentiated stem cells had a better performance
than differentiated (schwann cells) .

55. Effect of Platelet Rich Plasma on Facial Nerve Regeneration
 Platelets contain various growth factors such as platelet-derived
growth factor (PDGF), transforming growth factor-, and vascular
endothelial growth factor.
 When platelets are activated,they release these factors, which play
important biological roles in various conditions.
 It has been demonstrated that neurons express PDGF receptors,
PDGF- has been proven to be a survival factor for Schwann cells .
Also, an augmented PDGF- expression in peripheral neurons has
been found after peripheral nerve injury, suggesting a role in
peripheral nerve regeneration These findings have led some
authors to investigate the effects of PDGF, which has been found to
improve regeneration and remyelination of the nervous system.
 suturing of the nerve and application of PRP demonstrated the
greatest increase in the axon counts after treatment than
application of PRP without suturing .

56.  Georgiade Plastic, maxillofacial and reconstructive
surgery
 Peterson's Principles of Oral and Maxillofacial
Surgery ,2012
 Grabb___Smith_s_Plastic_Surgery__6th_Ed.2007
 Facial_Plastic_Reconstructive_and_Trauma_Surgery
 Articles from internet
references

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