3. Anatomy of Facial nerve
The facial nerve contains approximately 10,000
fibers
7000 myelinated fibers innervate the muscles of
facial expression, stapedius muscle,
postauricular muscles, posterior belly of digastric
muscle, and platysma
3000 fibers form the nervus intermedius (Nerve
of Wrisberg)
sensory fibers (taste) from the anterior 2/3 of the
tongue
taste fibers from soft palate via palatine and greater
petrosal nerve
6. Nuclear segment
Facial motor nucleus
lower 1/3 of Pons
abducent nucleus
Out from brain stem at pons recess
between olive and inferior cerebellar peduncle
7. Nervous intermedius
Parasympathetic secretory fibers arise
from superior salivatory nucleus
These preganglionic fibers travel to the
submandibular ganglion via the chorda
tympani nerve to innervate the
submandibular and sublingual glands
And to sphenopalatine ganglion via greater
superficial petrosal nerve to innervate
lacrimal, nasal, and palatine gland
8.
9.
10. Nervous intermedius
Secretory fibers of lesser superficial
petrosal nerve tranverse tympanic
plexus, synapse in otic ganglion,
and travel via auriculotemporal
nerve to innervate parotid gland
Taste fibers from anterior 2/3 of
tongue reach geniculate ganglion
via chorda tympani nerve and from
there travel to the nucleus of the
tractus solitarius
12. Cerebellopontine angle
The facial nerve and nervus intermedius exit the
brain stem at the pontomedullary junction and
travel with CN VIII to enter the internal acoustic
meatus
Internal acoustic
canalMotor facial nerve (medial)
Nervus intermedius (between)
Acoustic nerve (lateral)
13.
14. Labyrinthine segment
Fallopian canal
Shortest & Narrowest part
Temporal bone
Facial nerve enter fallopian canal until middle
ear
First genu
Geniculate ganglion
Branches
Greater superficial petrosal nerve lacrimal gland
Lessor superficial petrosal nerve parotid gland
15. Tympanic segment
First genu above oval window stapes
Second genu beyond middle ear
Out of cranium through stylomastoid foramen
16. Mastoid segment
Stylomastoid foramen
Branches
Motor nerve to stapedius
muscle
Chorda tympani nerve
between malleus and incus
secretomotor : Submandibular &
Sublingual gland
taste fiber : anterior 2/3 of
tongue
17.
18. Extracranial segment
Posterior auricular nerve : auricularis,
occipitalis and sensation at auricular, post
auricular area
Branch to posterior belly of digastric muscle
and stylohyoid muscle
Temporal branch : muscle above zygoma
Zygomatic branch : orbicularis occli
Buccal branch : buccinator and upper lip
Marginal mandibular branch : orbicularis oris
and lower lip
Cervical branch : platysma
32. House-Brackmann grading
system
The most commonly used facial nerve grading scale
is the House-Brackmann (HB) scale.
The HB scale is used to approximate the quantity of
volitional motion the patient has based on their clinical
facial presentation
Only grade six (6/6) presentations require EnoG
testing. That is, the purpose of the test is to determine
whether or not the facial nerve is neurophysiologically
intact. Therefore, if the patient has any volitional
motion (as would be evident with grades one through
five) the facial nerve is intact.
It is useful to chart the progress of facial nerve
disorders via ENoG even in cases with grades two
through five presentations.
33. Grade II - Mild dysfunction, slight weakness on
close inspection, normal symmetry at rest
34. Grade III - Moderate dysfunction, obvious but not
disfiguring difference between sides, eye can be
completely closed with effort
35. Grade IV - Moderately severe, normal tone at rest,
obvious weakness or asymmetry with movement,
incomplete closure of eye
36. Grade V - Severe dysfunction, only barely perceptible
motion, asymmetry at rest
37. Topographic Diagnosis
To determine the anatomical level of a peripheral
lesion
Lacrimation Geniculate ganglion
Stapedius reflex motor nerve of stapedius
muscle
Taste chorda tympani
38. Schirmer's Test
Geniculate ganglion &
petrosal nerve function
test
Schirmer’s test +ve
when
Affected side shows
less than half the
amount of lacrimation
seen on the normal
side
Sum of the lengths of
wetted filter paper for
both eyes less than
25 mm
Lesion at or proximal to
39. Stapedius reflex
Nerve to Stapedius
muscle test
Impedance audiometry
can record the
presence or absence of
stapedius muscle
contraction to sound
stimuli 70 to 100 dB
above hearing
threshold
An absence reflex or a
reflex less than half the
amplitude is due to a
40. Taste (Electrogustometry)
Chorda tympani nerve test
Solution of salt, sugar, citrate, quinine or
Electrical stimulation
Compares amount of current require for a
response each side of tongue
Normal : difference < 20 uAmp (thresholds
differening by more than 25%= abnormal)
Total lack of Chorda tympani : No response at
300 uAmp
Disadvantage : False +ve in acute phase of
Bell’s palsy
46. Idiopathic facial palsy (Bell's Palsy)
Most common cause of facial paralysis
(>50% of case)
Most age 25-30 yrs.
Male : Female = 1 : 1
Left side : Right side = 1 : 1
Unilateral > bilateral
Increase risk in
pregnancy 3.3 times
DM 4.5 times
Recurrent rate 10%
60% have previous URI
51. Medical treatment
Corticosteroids :
prednisolone 1 mg/kg/day 7-10 days
Corticosteroids combine with
antiviral drug is better
Acyclovir 400 mg 5 times/day
Famciclovir and valacyclovir 500 mg
bid
52.
53. Surgical treatment
Facial nerve decompression
Indication
Completely paralysis
ENOG less than 10% in 2 weeks
Appropriate time for surgery is 2-3
weeks after paralysis
54. The Brow
A brow lift by direct excision of tissue through an
incision just above the eyebrow is the most
effective technique.
Coronal
Endoscopic lift .
63. The Upper Eyelid
The simplest effective procedure is lid loading
with a gold prosthesis.
The lightest weight that will bring the eyelid within
2 to 4 mm of the lower lid and cover the cornea is
quite adequate.
The effectiveness of a gold weight placement can
be determined preoperatively by taping the test
weight with double-sided tape to the upper eyelid.
73. Direct nerve repair:
Usually possible for traumatic or iatrogenic injury to
nerve
Facial nerve grafting:
o Best performed within 3 weeks to 1 year of injury
o Immediate grafting after ablative surgery yields good
results
o Sources of cable grafts – cervical plexus, sural nerve
o Method of choice - no tension epineural repair
78.
Nerve crossovers:
o Used when direct suturing or grafting is not feasible
o But movement is uncoordinated (synkinesis) and there
is loss of function in the donor nerve
• Synkinesis can be palliated by injections of botulinum toxin
around orbicularis oculi muscle.
• This reduces involuntary closure of the eye when
attempting to smile.
o Donor nerves – glossopharyngeal, accessory, phrenic,
hypoglossal
o Most suited to immediate reconstruction of facial nerve
trunk as part of primary ablative surgery