The document discusses the trigeminal and facial nerves, which provide sensory and motor innervation to the face. It covers their anatomy, clinical assessment, and common injuries. The trigeminal nerve has three main branches - the ophthalmic, maxillary, and mandibular nerves. It provides sensory innervation and some motor functions. The facial nerve innervates the muscles of facial expression. Common causes of injury include local anesthetic injections, surgery like third molar removal or dental implants, and traumatic injuries. Assessing trigeminal nerve function involves testing sensation and motor functions like the jaw jerk reflex.
3. Introduction-
• Cutaneous/ sensory innervation to the face
is predominantly provided by the trigeminal
nerve and the motor supply to the face is
predominantly provided by the facial nerve.
• Dental treatment, surgical operations, and
traumatic injuries to the oral cavity and
maxillofacial region occur in close
proximity to the three major divisions of the
5th cranial (trigeminal) nerve and the facial
nerve.
4. Trigeminal Nerve-
• The trigeminal nerve (V) is a mixed nerve: sensory
for regions of the face and motor for the muscles of
mastication. The sensory root is large, while the
motor root is more slender. By way of its
connections, the trigeminal nerve has sensory and
secretory fibers.
• The nerve divides into three branches: ophthalmic
(V1), maxillary (V2) and mandibular (V3). The
mandibular nerve is a mixed nerve, while the other
two branches are sensory
5. Origin-
• The origin of the trigeminal nerve is
the annular protuberance at the
limit of the cerebellar peduncles. It
emerges from the pons by two roots
of unequal size: a small motor root
and a large sensory root.
• The large sensory root is made up of
about 50 fascicles.
• The small root, the motor root of
Wrisberg, is composed of six or
seven fascicles.
6. Course of trigeminal nerve-
• Exits from the anterolateral surface of pons
as - large sensory & small motor root.
• Roots enter into middle cranial fossa by
passing over the medial tip of the petrous
part of the temporal bone.
• Sensory root expands into the trigeminal
ganglion.
• The ganglion lies in a depression –
Trigeminal Cave
• Three terminal divisions arise from the
anterior border of the Trigeminal ganglion.
7. Trigeminal Ganglion-
• Formerly known as the ganglion of Gasser,
the trigeminal ganglion nestles in the
trigeminal cave, where it divides into three
branches.
• The trigeminal ganglion is shaped like a
very flat bean. Its anterolateral surface is
intimately linked to the dura mater, to
which it strongly adheres.
• The trigeminal ganglion sends fibers to the
dura mater, the sphenotemporal region and
the petrosal sinus.
8. Nuclei of Trigeminal nerve-
Nucleus Input Output Function
Motor Ipsilateral and contra
lateral primary motor
cortices.
Sensory nucleus of
trigeminal nerve
Muscles of mastication
Tensor tympani
Tensor veli palatini
Mylohyoid
Anterior belly of digastric
Motor information
Chief sensory Primary afferent fibres Ventral posteromedial
nucleus of thalamus
Pain, temperature and
light touch from head
Spinal tract and nucleus Aδ and C fibres Ventral posteromedial
nucleus of thalamus
Pain and temperature
Mesencephalic Muscle spindles
Periodontal ligament
TMJ
Reticular formation
Cerebellum
Motor neuron
Non conscious
proprioception of face
Jaw jerk reflex
10. Functions-
• The trigeminal nerve is the great
sensory nerve of the face. Its territory
is delimited by the coronal line passing
through the vertex, the tragus and the
inferior border of the mandible.
Sensory function
• The supra-ocular area is innervated by
the ophthalmic nerve.
• The inter-oculo-buccal area is innervated
by the maxillary nerve.
• The infrabuccal area is innervated by the
mandibular nerve.
11. Ophthalmic nerve
Origin -arises from the anteromedial part of the trigeminal ganglion
(of Gasser).
Pathway - travels forward obliquely and supero medially towards the
superior orbital fissure of the sphenoid
Useful relationships- The ophthalmic nerve runs below the trochlear
nerve. It is joined by filaments of the carotid plexus and
communicates with the oculomotor nerve.
Anastomoses- The ophthalmic nerve exchanges nerve fibers with the
three motor nerves of the eye: • the trochlear nerve (IV) • the
oculomotor nerve (III) • the abducent nerve (VI)
Collateral branches- sends an important sensory branch to the
tentorium cerebelli and to the posterior part of the falx. This is known
as the recurrent meningeal nerve of Arnold.
The terminal branches- of the ophthalmic nerve are the nasociliary,
frontal and lacrimal nerves
12. Lacrimal nerve
• Smallest of the main branches of the ophthalmic nerve.
• Enters the orbit through the narrowest part of the
superior orbital fissure, to reach the lacrimal gland.
Anastomoses- The lacrimal nerve anastomoses with the
trochlear nerve and the orbital branch of the maxillary
nerve.
Some of these terminal branches enter the lacrimal gland;
others extend to the lateral aspect of the superior eyelid.
The lacrimal nerve can be reached at the lacrimal gland
and more easily at the level of the eyelid.
13. Frontal nerve
• Enters the orbit through the superomedial aspect of the
superior orbital fissure, without passing through the
common tendinous ring.
• Terminal branches-
• The supratrochlear nerve (internal frontal) runs towards
the inner corner of the eye. It gives off filaments supplying
the frontal periosteum, the skin of the lower part of the
forehead, and the upper eyelid and its conjunctiva.
• The supra-orbital nerve (external frontal) passes through
the supra-orbital foramen. It innervates the upper eyelid, the
conjunctiva and the skin of the forehead. Small branches
perforate the occipitofrontalis muscle to supply the
lambdoid suture, the diploë of the frontal bone and the
mucosa of the frontal sinus
14. Nasociliary nerve-
The nasociliary nerve passes through the superomedial aspect of the
sphenoid fissure, within the common tendinous ring (annulus of
Zinn). It runs towards the medial part of the orbital cavity to end at
the medial anterior orbital foramen.
Collateral branches are given off to:
• the ophthalmic ganglion
• the ciliary nerves
• the spheno-ethmoidal branch (the posterior ethmoidal nerve),
which supplies the sphenoidal and ethmoidal sinuses.
The terminal branches of the nasociliary nerve are:
• The infratrochlear nerve (external nasal), a branch of which goes
to the lacrimal canal and the medial eyelid.
• The supratrochlear nerve. This branch is also called the ethmoidal
filament for the cribriform plate, over which it passes.
• A branch supplies the frontal dura mater.
• Nasal branches.
15. Maxillary nerve
• Origin-begins at the middle of the trigeminal ganglion
and is intermediate between the ophthalmic and
mandibular nerves
• Pathway- leaves the skull through the foramen
rotundum and arrives in the superior part of the
pterygopalatine fossa. It enters the inferior orbital
fissure, crosses the infra-orbital groove, and appears on
the face through the infra-orbital foramen. At its origin it
is surrounded by a double layer of dura mater.
• Innervation-
• Dura mater of the middle cranial fossa, mucosa of the
nasopharynx, palate, nasal cavity, nasopharynx, teeth,
upper jaw, skin over the side of nose, lower eyelid,
cheek, upper lip
16. Maxillary nerve branches-
• The branches of the maxillary nerve are:
1. Inside the cranium : Nerve to the dura
2. At the pterygopalatine fossa area:
Ganglionic Branches
Zygomatic nerve
Anterior zygomaticofacial
Posterior zygomaticotemporal
Post superior alveolar ,greater and laser palatine
3. Infra orbital canal
Middle superior alveolar
Anterior superior alveolar
4. On face
Infra orbital- Palpebral, Labial, Nasal
17. Mandibular nerve-
• Origin- proceeds from the most lateral part of
the trigeminal ganglion. It is the most vertical of
the trigeminal nerve branches.
• Pathway The two roots of the mandibular nerve
are sheathed in a doubling of dura mater. The
motor root runs along the floor or
the trigeminal cave, beneath the ganglion,
joining the sensory root before leaving the
cranium through the foramen ovale.
• Once the mandibular branch has emerged from
the cranium, it courses through
the infratemporal fossa, giving rise to anterior
and posterior trunk.
18. Branches of mandibular nerve-
Main trunk-
• Nervus spinosus- nerve to the dura mater
• Nerve to the medial pterygoid
Tensor veli palatini
Tensor tympani
Medial pterygoid
Anterior division
• Deep temporal
• Lateral pterygoid
• Masseteric
• Buccal- skin of cheek
Posterior division-
• Auriculotemporal
Auricular
Superficial temporal
Articular to the TMJ
Secretomotor to the parotid gland
• Lingual- General sensation from the anterior
two thirds of the tongue
• Inferior alveolar
Mental nerve
nerve to he mylohyoid
19. Auriculo temporal nerve
• Superior root – comprises sensory fibers.
• Inferior root – carries secretory-motor
parasympathetic fibers, originating from CN IX, to
the parotid gland.
• The two roots converge in close proximity to the
middle meningeal artery. After converging, the
secretory-motor fibers run to synapse in the otic
ganglion, while the sensory fibers pass through the
ganglion without synapsing to eventually innervate:
Anterior part of the auricle
Lateral part of the temple
Anterior external meatus
Anterior tympanic membrane
20. Buccal nerve-
• The buccal branch of the mandibular nerve
contains sensory fibres. As it emerges from the mandibular
nerve, it passes between the two heads of the lateral
pterygoid muscle before heading to its target sites.
• The nerve provides general sensory innervation to
the buccal membranes of the mouth (i.e. the cheek). It also
branches to supply the second and third molar teeth, which
is important when performing dental work on those
structures.
21. Inferior alveolar nerve-
• The inferior alveolar nerve carries
both sensory and motor axons to and from the respective
trigeminal nuclei.
• After branching from its parent nerve it gives rise to
the mylohyoid nerve, a motor nerve to the mylohyoid and
anterior digastric muscles.
• The remaining sensory axons enter the mandibular canal, a
narrow tunnel running through the mandible bone. Within
this canal the nerve provides branches to the mandibular
teeth.
• The nerve emerges through the mental foramen as
the mental nerve. This provides sensory innervation to the
lower lip and chin
22. Lingual nerve
• This branch of the trigeminal nerve carries
general sensory axons. It also acts as a conduit
for special sensory and autonomic fibers
belonging to the chorda tympani, a branch of
the facial nerve (CN VII).
• General sensory fibers innervate
the anterior two-thirds of the tongue, as well as
the mucus membrane lining its undersides.
• The special sensory fibers carry on with the
lingual nerve to provide taste to the anterior two-
thirds of the tongue.
• The autonomic fibers branch to synapse in
the submandibular ganglion, eventually
innervating the submandibular and sublingual
glands
23. Clinical assessment-
• Two aspects of the trigeminal nerve should be assessed – the motor and
sensory components.
1. Always take a detailed history from the patient.
3. Observe the skin over the area of temporalis and masseter first to identify
if any atrophy or hypertrophy is obvious.
24. 3) Palpate the masseter and temporalis muscles while you
instruct the patient to bite down hard.
4) Ask the patient to open their mouth with resistance
applied by the examining clinician at the bottom of the
patient’s chin.
25. 5.Jaw jerk reflex- ask the patient to have their mouth half
open and half closed. Place an index finger at the mental
protuberance, and tap it with a tendon hammer. Normally
the reflex is light, but pronounced for patients with an
upper motor neuron lesion.
6. Gross sensation- Tell the patient to close their eyes and
say “sharp” or “dull” when they feel an object touch their
face. Using the needle, brush or cotton wool, randomly
touch the patient’s face with the object. Touch above each
temple, next to the nose and on each side of the chin, all
bilaterally. Ask the patient to also compare the strength of
the sensation of both sides.
26. 7. Corneal reflex (blink reflex)- Ask the patient to look at
a distant object and then approaching laterally, touching the
cornea with fine cotton checking if the eyes blink. Repeat
this on the opposite eye
27. Trigeminal nerve injury
Etiology:
• Local anesthetic injections
• Viral infections
• Intra cranial tumour
• Mandibular third molar removal
• Orthognathic surgery
• Maxillofacial trauma
• Dental implants and pre-prosthetic surgery
• Endodontic treatment
• Salivary gland surgery
• Ablative/oncologic surgery
• Cosmetic surgery
28. Injury due to LA injection
1. Direct neural trauma resulting in
separation of the fascicles by a needle or
suture.
2. Local anesthetic toxicity may be
responsible for prolonged paresthesia
following a mandibular block, especially if
the solution is deposited within the confines
of the epineurium.
Mechanism:
*Katyal V (2010) The efficacy and safety of articaine versus lignocaine in dental treatments: a meta-analysis. J
Dent 38:307–317
3. Third potential mechanism :formation of an epineurial hematoma. The epineurium and
perineurium contain a vast plexus of vessels that nurture the neural elements, and a needle
may cause disruption of one or more vessels.
29. Viral etiology
• Post herpetic neuralgia is
seen in elderly patients.
• H/O of varicella zoster
infection may be present in
these patients.
• Viral lesions of the ganglion
can be the etiological factor.
30. Intracranial tumour
• Lesions such as epidermoid tumors,
meningiomas and arteriovenous
malformations, aneurysms and
vascular compression suggested as
the causes.
31. Incidence
Temporary Injury:
0.4% (4/1000)- IAN injury*
0.1% (1/1000)- LN injury*
Permanent injury:
0.04% (1/2500)- IAN injury*
0.01% (1/10,000) – LN injury*
• Position of Lingual Nerve- 2.28 mm
inferior to the crest & 0.58 mm lingual to
the lingual cortex of mandible in 3rd molar
region.
• LN resides in soft tissue
Third molar surgery causing nerve injury-
*Meyer et al, Nerve Injuries from Mandibular Third Molar Removal Atlas Oral Maxillofacial Surg Clin N
Am 19 (2011) 63–78
32. Risk factors-
Inferior alveolar nerve Lingual nerve
• Older age
• Dilacerated root tips in close proximity
to the inferior alveolar canal (IAC)
• Apical root thirds extending into the
IAC
• Dense bone
• Poor surgical access
•Lingual surgical approach
•Superiorly positioned lingual nerve
•Perforation of the lingual plate during
surgical third molar removal
•Lingual positioning of third molar
•Root apices extending into the lingual
plate
33. Dental implant-related injuries
of the trigeminal nerve-
• Etiology:
• Preoperative errors in evaluation, diagnosis, and
treatment planning
• Local anesthetic injection
• Excessive implant osteotomy preparation (drilling)
or overheating due to drilling
• Impingement of the implant on the inferior
alveolar canal and neurovascular bundle
• Inadvertent transection of the mental, lingual, or
long buccal nerve during incision and/or soft tissue
flap retraction. (with age the alveolar ridge resorbs
and postion of mental foramen changes)
Less common causes of nerve injury are related to placement of bone grafts (autologous,
allogenic, xenogenic) during simultaneous implant placement.
34. Orthognathic Injuries and the Trigeminal Nerve
Mandibular Osteotomies :
• Vertical ramus osteotomy
• Bilateral Sagittal split ramus osteotmy(BSSO)
• Genioplasty
Maxillary Osteotomies:
• Lefort I osteotomy
Clearly, the BSSO, which splits the mandible along 2–3 cm of the mandibular body and ramus,
must be considered as a high-risk procedure for the IAN coursing in the same bony structure, at
least much more than the VRO and genioplasty,
35. Points to be considered-
• The vertical osteotomy should be made in the first
or second molar region to avoid the most lateral
position of the IAN in the third molar region.
• Also, the depth of the osteotomy should be limited
to 2–3 mm in the first molar region to avoid the
IAN
• The horizontal osteotomy should be made at a
reasonable distance above the mandibular
foramen on the medial aspect of the ramus to
avoid the IAN as it enters the mandible
• Use of a spreading instrument (e.g., Smith
spreader) instead of sharp chisel to complete the
BSSO.
36. • Those sides where the nerves were embedded in
the distal fragments (dentate segment) do better
than those with nerves embedded in the proximal
segments.
• use of the monocortical mini-plate permits
passive contact of the proximal and distal
segments without compression on the IAN
37. • Recently a study by Doucet et al. indicated that if impacted third molars were removed during
BSSO, rather than before, the incidence of nerve damage was reduced*.
• Low-level laser (LLL) treatment perioperatively at the mandibular foramen, mental foramen, and
lower lip and chin region using a gallium aluminum-arsenide (Ga-Al-Ar) laser at 820 nm have
shown promising results in IAN injury after BSSO**.
2012
2000
38. Trigeminal Neuralgia-
According to the International Classification of Headache
Disorders –
TN is characterized by recurrent unilateral brief electric
shock-like pains, abrupt in onset and termination, limited
to the distribution of one or more divisions of the
trigeminal nerve and triggered by innocuous stimuli. It
may develop without apparent cause or be a result of
another diagnosed disorder.
• The name “tic douloureux” was coined by Nicholaus
Andre, referring to the spasm of the face that follows
an attack of pain.
• John Fothergill first codified the clinical
characteristics of the disease in his paper “On a Painful
Affliction of the Face,” which was published in
London in 1775
39. General features-
• The annual incidence is between 4 and 5 in
100,000.
• It typically affects people older than 50
years, although instances of the disease in
young adults and even children have been
reported.
• There is a slight female predominance.
• Sides: Predilection for the right side (60%).
• Strong environmental or genetic predisposing
factors are not apparent.
40. • ICHD-II further subdivides trigeminal neuralgia into ‘‘classic trigeminal neuralgia’’ and ‘‘symptomatic
trigeminal neuralgia.’’
Classic Trigeminal Neuralgia Symptomatic Trigeminal Neuralgia
• Defined as a unilateral disorder characterized by brief
electric shock like pains, abrupt in onset and termination,
limited to the distribution of one or more divisions of the
trigeminal nerve.
• Pain is evoked by trivial stimuli including washing,
shaving, smoking, talking and/or brushing the teeth
(trigger factors) and frequently occurs spontaneously.
• Small areas in the nasolabial fold and/or chin may be
particularly susceptible to the precipitation of pain
(trigger areas). The pains usually remit for variable
periods.
• Symptomatic trigeminal neuralgia has the same key
features of trigeminal neuralgia but results from another
disease process (such as multiple sclerosis or a
cerebellopontine angle tumor).
• Symptomatic trigeminal neuralgia is defined by IHS as
‘‘Pain indistinguishable from classic trigeminal neuralgia
but caused by a demonstrable structural lesion other
than vascular compression.’’
Classification-
41. Clinical features-
• Afflicted patients typically describe the pain as
electric, shooting, and shock like.
• The pain occurs in attacks, each of which lasts only
seconds or less; however, attacks tend to cluster so
that pain free episodes may not be appreciated.
• Pain can be precipitated by light mechanical
stimulation to small trigger zones in the face or oral
mucosa.
• Frequent triggers include light touch, wind, brushing
teeth, speaking, eating, and drinking.
• There may be ipsilateral muscle spasm described in
the condition termed tic douloureux.
• The disease typically takes a sporadic course, with
remissions that may last months or even years.
• Most people have normal neurological examinations
and are symptom free between attacks.
42. Clinical characteristics
• The patient will have a motionless
face: frozen or mask like face.
• With each attack, the pain seems to
become more intense and unbearable.
• Pain never crosses mid line of face
• It characteristic ,that attacks do not
occur during sleep.
Rasmussen P: Facial pain. III. A prospective study of the
localization of facial pain in 1052 patients, Acta Neurochir (Wien)
108:53, 1991.
Tacconi L, Miles JB: Bilateral trigeminal neuralgia: a therapeutic
dilemma, Br J Neurosurg 14:33, 2000
43. Distribution of pain-
• The vast majority of cases affect either the second or third division
(V2 or V3), alone or in combination. In only 4% to 5% of patients,
symptoms occur solely in the first
44. Pathophyiology-
• Jannetta and colleagues showed that surgical decompression
of the nerve root can effectively alleviate the symptoms of
trigeminal neuralgia
• In a number of patients who undergo surgical exploration, no
compressing vessel or lesion has been identified.
• Pathologic rhizotomy specimens have demonstrated focal loss
of myelin with close apposition of the demyelinated axons.
• In the study by Devor and colleagues, 1 of the 12 patients was
not found to have vascular compression, and the rhizotomy
specimen from this patient showed only “modest
demyelination”.
• Devor and his colleagues proposed their “ignition hypothesis”
by which nerve compression leads to an increase in neuronal
activity and reduced firing thresholds.
45. Diagnosis-
• The White and Sweet criteria for trigeminal neuralgia were a major
advance that facilitated research and enabled early and accurate
clinical recognition of the syndrome.
# The criteria were incorporated, largely unchanged, into the official research diagnostic framework criteria
published by the International Association for the Study of Pain (IASP) and the International Headache Society
(IHS).
47. Imaging-
• Because a significant percentage of patients have symptomatic trigeminal
neuralgia resulting from another disease process, diagnostic brain
imaging studies should be part of the initial evaluation of any patient with
trigeminal neuralgia symptoms.
• Although a routine brain CT scan is usually adequate to screen for a
cerebellopontine tumor, an MRI scan often better demonstrates multiple
sclerosis plaques and the anatomic relationships of the trigeminal root.
• Magnetic Resonance Tomographic Angiography (MRTA)- indicate
neurovascular compression.
• Other diagnostic studies, such as blood studies, lumbar puncture, and
evoked potentials, are generally not necessary
48. Management
Non surgical Surgical
Local anaesthetics
Anticonvulsants
Carbamazepine
Gabapentin
Phenytoin
Alcohol and glycerol injection
Peripheral neurectomy
Infraorbital neurectomy
Inferior alveolar neurectomy
Lingual neurectomy
Trigeminal rhizotomy
This is a long-term prospective longitudinal study comparing 15 patients who were
followed for a mean duration of 15 years on the effectiveness of medical
(oxcarbazepine) versus surgical therapy. The study indicated that mean time to
recurrence of pain following oxcarbazepine therapy was 8 months and with surgical
therapy it was 28 months
49. Medical management-
• Carbamazepine has been the mainstay of medical treatment for
trigeminal neuralgia for many years.
• Bergouignan in 1942 noted that the anticonvulsant phenytoin
effectively controlled attacks of pain in the condition.
• Baclofen is another choice for monotherapy for trigeminal
neuralgia as was evidenced in data from Fromm and colleagues .
• Clonazepam is a benzodiazepine with anticonvulsant properties
and is also effective for suppression of pain attacks. Gabapentin,
topiramate, oxcarbazepine, tiagabine, levetiracetam, and
zonisamide have also been effective in treatment of trigeminal
neuralgia.
#In a retrospective study of anticonvulsant therapy, Scrivani and
coworkers found that 50% of patients reported satisfactory pain
relief while taking a single antiepileptic drug, whereas 70% of
those taking two drugs reported a satisfactory response.
51. Interventional-
These can be broadly classified as
• Peripheral techniques
• Those directed at the Gasserian ganglion
• Neurostimulation
#In general, when surgical options are considered, techniques directed at the Gasserian ganglion have
largely replaced peripheral techniques.
52. Peripheral Techniques-
• Peripheral nerve ablation is a procedure that
locally blocks the division of the trigeminal
nerve involved with pain.
• The means of ablation typically include local
(peripheral) blocks with local anesthetics,
neurectomy of the involved trigeminal branch
under local anesthesia, cryotherapy or
neurolytic blocks with alcohol or phenol
53. Orbital nerve block-
• The ophthalmic nerve per se is not blocked in the treatment of
trigeminal neuralgia because it leads to keratitis.
• The supraorbital and supratrochlear branches can be individually
blocked.
• The supratrochlear nerve can be injected at the superior medial
corner of the orbital ridge with 1 mL of local anesthetic with or
without corticosteroid.
• The supra orbital nerve can be injected at a distance of 1 cm from
the superior medial corner of the orbital ridge with 1 mL of local
anesthetic with or without corticosteroid
• The inferior orbital nerve can be injected at the inferior orbital
foramen which is 1 cm below the orbit and is usually located
with a needle inserted about 2 cm lateral to the nasal and directed
superiorly, posteriorly, and slightly laterally .
54. Maxillary nerve block-
• With the patient’s mouth opened, a 3.5-inch, 25-
gauge needle can be inserted between the
zygomatic arch and the notch of the mandible.
• At about 3 to 4 cm in depth, contact will be made
with the lateral pterygoid plate.
• Withdraw the needle 1 cm and angle it superiorly
and anteriorly to pass into the pterygopalatine
fossa.
• Local anesthetic (4 to 6 mL) can then be instilled
here after negative aspiration.
• This technique anesthetizes the maxillary nerve
and the sphenopalatine ganglion.
• There is a risk of hemorrhage when blocking the
maxillary nerve with this technique
55. Mandibular nerve block-
• The mouth is slightly opened and a 25-gauge, 3.5-inch needle
is advanced between the zygomatic arch and the mandibular
notch.
• After contact with the lateral pterygoid plate, withdraw the
needle one centimeter and angle superior and posterior toward
the ear.
• About 4 to 6 mL of local anesthetic is then instilled at this
location after negative aspiration. The facial nerve may at times
be unintentionally blocked with this technique.
• The lingual and inferior mandibular nerves can be injected with
the mouth opened and by palpating the coronoid notch.
• The needle is introduced medial to the notch but lateral to the
pterygomandibular fold and advanced posteriorly about 2 cm
along the medial aspect of the mandibular ramus where 2 to 3
mL of local anesthetic, when instilled, will block both nerves.
• The inferior alveolar nerve is blocked as it emerges from the
mental foramen at mid-mandible 2 mL of local anesthetic is
instilled when paresthesias are elicited or the needle enters the
foramen.
56. Peripheral Neurectomy-
• Peripheral neurectomy is a simple, low-risk
procedure that can be done on all terminal
branches of the 3 divisions of trigeminal nerve.
Peripheral neurectomies were first tried in 1830
• This procedure can be done in outpatient setting
without general anesthesia. It is a post-
ganglionic surgical operation, which involves an
avulsion of the nerve after its exit from the
cranium.
• It is an effective and safe treatment in rural
areas, which lack the facilities for neurosurgical
procedures, in elderly patients and in patients
who are reluctant for major surgeries.
57. Infra orbital neurectomy-
• Infraorbital neurectomy is performed
through vestibular incision,
dissection is carried out to expose the
nerve. An infraorbital nerve is
clamped and avulsed.
• The orifice of the infraorbital
foramen is then sealed by using a
stainless steel screw
58. Inferior alveolar nerve neurectomy--
• Inferior alveolar neurectomy: (Through
Ginwala's incision)
• An inverted Y-shaped incision is made
along the anterior border of ascending
ramus, which is then deepened on its
medial aspect by means of a blunt and
sharp dissection.
• The temporalis and medial pterygoid
muscles are split, and the nerve is
located, clamped and then cut below the
instrument.
• Then the mental nerve is clamped at the
mental foramen and avulsed
59. • The indications, advantages, complications, and benefits of
peripheral neurectomy in patients with trigeminal
neuralgia were studied in detail in 40 patients treated
between 1982 and 1991.
• Twenty-eight patients had previously received
radiofrequency thermocoagulation: peripheral neurectomy
was performed for pain recurrence.
• These patients had excellent or good pain relief for at least
5 years postsurgery.
• Of the 12 patients who had peripheral neurectomy as their
only procedure, seven had an excellent result and five had
a good result.
• Five of the patients had recurrence of pain after 2 years but
responded well to a second neurectomy.
• Elderly patients who experienced pain in the first and
second divisions of the trigeminal distributions were the
best candidates. Peripheral neurectomy is an effective, safe
procedure for elderly patients who suffer from trigeminal
neuralgia and have a limited life span.
The aim of this prospective study is to evaluate the long
term efficacy of peripheral neurectomy with and without
the placement of stainless steel screws in the foramina and
to calculate the mean remission period.
Study was done on 2 groups of 14 patients each
Post-surgical pain relief varied from 15 months to 24
months in cases where neurectomy was done without
placing stainless steel screws in the foramina. Those cases
where peripheral neurectomy was done along with the
placement of stainless steel screws in the foramina, none of
the patient had painful symptoms even after minimum 2
years of follow-up.
60. Cryotherapy-
• Cryotherapy is the therapeutic use of
extremely low temperatures to destroy
cells by crystallizing the cytosol to obtain
pain relief.
• Under local anesthesia, the affected nerve
is exposed surgically and a cryoprobe is
placed directly on the nerve for three 2-
minute freeze-thaw cycles.
• Few complications have been reported;
sensation, although initially lost, returns
before pain recurs.
61. Neurolytic Peripheral Blocks-
• Neurolytic peripheral blocks of the trigeminal nerve and its branches
are usually done with phenol or alcohol.
• A paper by Fardy and Patton, reported on a series of 413 alcohol
blocks administered over a 20-year period. The mean period of pain
relief was 13 months, and only three (0.73%) significant
complications were noted. These included local tissue necrosis,
diplopia, and sensory loss.
• Disadvantages to this procedure include sensory loss in the
distribution of the treated nerve and a high rate of recurrence of pain
owing to nerve regeneration with subsequent deafferentation pain.
62. Gasserian Ganglion Techniques-
• Techniques targeting the Gasserian ganglion can broadly
be classified into ablative and decompressive
approaches.
• Percutaneous trigeminal ablation of the Gasserian
ganglion is usually performed by a specially designed
device inserted into the cheek or through the mouth.
• Under radiographic guidance with fluoroscopy or CT,
the device is directed through the foramen ovale into the
Gasserian ganglion or retrogasserian rootlets.
• The methods of ablation typically include
radiofrequency coagulation, glycerol injection, and
mechanotrauma by balloon ablation.
63. Radiofrequency Thermocoagulation-
• Radiofrequency thermocoagulation is the most common surgical
treatment for trigeminal neuralgia.
• The foreman ovale is identified with a C-arm fluoroscopy. A 2-mm
active-ended RF electrode is inserted and advanced parallel to the
axis of the fluoroscopy till passing the foramen ovale border. After
aspiration test stimulation was applied at 2 Hz, 0.1–1.5 V for motor
stimulation and 50–100 Hz, 0.1–1.5 V for sensory stimulation with
observing movement and sensory changes. After confirming the
position of the electrode, radiofrequency thermocoagulation is applied
at 70 °C for 90 s.
Akbas et al (2019)- A total of 19 patients were recruited into the study
(56.32 ± 13.48 years, 21% males, 79% females). There was more than
50% improvement in VAS score (16 patients, 79% versus 3 patients,
21%) (p < 0.05)
64. Glycerol Injection-
• Percutaneous injection of glycerol was described initially by
Hakanson. Glycerol injection involves the injection of sterile
glycerol into the gasserian ganglion and retrogasserian rootlets.
Placement of the needle adjacent to the ganglion is confirmed
with contrast cisternogram. The procedure results in significant
initial pain relief.
75 patients with trigeminal neuralgia were treated by the
injection of 0.2 to 0.4 ml of glycerol by the anterior
percutaneous route into the trigeminal cistern. 86 % of the
patients were completely free from pain after the treatment. No
complications have been observed.
65. Balloon Microcompression
• Balloon microcompression of the trigeminal ganglion is done
with a Fogarty balloon catheter that can be inserted under
fluoroscopy. This requires the use of a larger needle (14 gauge)
from which a catheter is threaded through the foramen ovale.
The balloon is inflated to predetermined pressure. This can
cause temporary motor loss.
• Lichtor and colleagues reported a 10-year follow-up in a series
of 100 patients. At 5 years, the recurrence rate was 20%, and at
10 years, it is estimated that 70% of patients will still be pain
free.
66. Stereotactic radiosurgery-
• A stereotactic head frame is screwed onto the skull, and stereotactic
imaging is performed. The trigeminal system is irradiated. A maximum
radiosurgical dose of 70 Gy or greater was associated with a greater
chance of complete pain relief. Pain relief begins approximately 3 to 6
months after the procedure.
• Disadvantages -20% to 30% risk of decreased sensation in the nerve
after the treatment.
• Radiosurgery involves the application of ionizing radiation to a portion of
the brain. The long-term effects of targeted radiation to the brain have not
been studied.
• Kondziolka and associates reported 80% initial pain relief in 106 patients
who were followed for 18 months. Ten percent of the patients developed
dysesthesia as a complication
67. Decompressive Procedures-
• The compression of the trigeminal nerve from blood vessels or tumors is
thought to result in demyelination of the nerve.
• Microvascular decompression involves a craniotomy to expose the nerve
at the base of the brainstem and to then insert a tiny
polytetrafluoroethylene (Teflon) pad between the compressing vessel and
the nerve. This Teflon pad isolates the nerve from the pulsating effect and
pressure of the blood vessel
A total of 504 patients with TN underwent surgery in 1998-2018.
Patients with TN following VBD were included. All patients had pain-
free early postoperative period. There were no deaths or major
complications.
69. Introduction-
• Mixed nerve: Motor, parasympathetic and
special sensory (taste)
• 2 roots: Motor and sensory (nervus
intermedius) roots
• Nervus intermedius exits lateral brainstem
between motor root of facial and
vestibulocochlear nerves, hence its name
• 4 segments: Intraaxial, cisternal,
intratemporal and extracranial (parotid)
70. Functional components-
• Special visceral or brachial efferent, to the
muscles responsible for facial expression
• General visceral efferent or parasympathetic
which are secretomotor to the submandibular,
sublingual salivary glands, the lacrimal gland,
glands of nose, palate and pharynx.
• General visceral afferent component carries
afferent impulses from the above mentioned
glands
• Special visceral afferent fires carry taste
sensations from the palate and from the
anterior two thirds of the tongue except from
vallate papillae.
• General somatic afferent fires probably
innervate a part of the skin of the ear.
71. Nuclei of facial nerve
3 nuclei (1 motor, 2 sensory)
• Motor nucleus of facial nerve
‒ Located in ventrolateral pontine tegmentum
‒ Efferent fibers loop dorsally around CNVI nucleus in floor of 4th
ventricle forming facial colliculus
‒ Fibers then course anterolaterally to exit lateral brainstem at
pontomedullary junction
• Superior salivatory nucleus
‒ Located lateral to CNVII motor nucleus in pons
‒ Efferent parasympathetic fibres exit brainstem posterior to
CNVII as nervus intermedius – To submandibular, sublingual, and
lacrimal glands
• Solitarius tract nucleus
‒ Termination of taste sensation fibers from anterior 2/3 of tongue
‒ Cell bodies of these fibers in geniculate ganglion
‒ Fibers travel within nervus intermedius .
72. Facial nerve
Intraaxial Segment
• 3 nuclei (1 motor, 2 sensory)
Cisternal Segment
• 2 roots in cisternal segment- Larger motor root anteriorly and smaller sensory nervus
intermedius posteriorly
• 2 roots join together and pass anterolaterally through cerebello pontine angle cistern
with CNVIII to internal auditory canal (IAC)
Intratemporal Segment
CNVII further divided in temporal bone into 4 segments: IAC, labyrinthine, tympanic,
and mastoid
• IAC segment: Porus acusticus to internal auditory canal fundus
• Labyrinthine segment: Connects fundal CNVII to geniculate ganglion (anterior
genu)
• Tympanic segment: Connects anterior to posterior genu
• Mastoid segment: Inferiorly directed from posterior genu to stylomastoid foramen
Extracranial Segment
CNVII exits skull base through stylomastoid foramen to enter parotid space
Parotid CNVII passes lateral to retromandibular vein
Ramifies within parotid, passes anteriorly to innervate muscles of facial expression
73. Course-
• Attached to the lateral part of lower border of pons by two
roots-motor and sensory. Sensory root is also called nervus
intermedius.
• The two roots run laterally and forwards with the 8th cranial
nerve to reach interna acoustic meatus.
• In the meatus, the motor root lies in a groove on the eighth
nerve, with the sensory root intervening. Here the seventh
nerve is accompanied by labyrinthine vessels.
• At the bottom of the meatus, the two roots fuse to form a single
trunk, which lies in petrous temporal bone.
• Within the canal, the course of the nerve can be divided into
three parts by two bends
• First part- directed laterally above the vestibule
• Second part- runs backwards along the medial wall of middle
ear
• Third part- vertically downward behind the promontory
74. • First bend (genu)- over the anterosuperior part
of promontory and is sharp
• Second bend- is gradual and lies between the
promontory and the aditus to the mastoid
antrum
• Leaves the skull by passing though the
stylomastoid foramen. After leaving the skull ,
it crosses the lateral side of the base of the
styloid process an enters the posteromedial
surface of the parotid gland.
• It runs forwards through the gland, crossing the
retromandibular vein and the external carotid
artery. Behind the neck of the mandible, it
divides into its five terminal branches which
emerge along the anterior border of the parotid
gland
75. Branches-
Within the facial canal:
• Greater petrosal nerve
• Nerve to the stapedius
• Corda tympani
As it exits from the stylomastoid foramen:
• Posterior auricular
• Digastric
• Stylohyoid
Terminal branches within the parotid gland:
• Temporal
• Zygomatic
• Buccal
• Marginal mandibular
• Cervical
76. Temporal Branch
Landmarks-
• A point 0.5 cm below the tragus.
• Average 2.85+- 0.69 cm superior to lateral canthus and 1.5 +_0.43 cm
lateral to LC ,cross the zygomatic arch .
Supply-
• Frontalis , orbicularis oculi, corrugator supercilli.
• Incision parallel to course of facial nerve can prevent injury to nerve .
Testing-
• Ask the patient to look upward without moving the head and note the
appearance of wrinkles on forehead.
77. Zygomatic branch-
• The zygomatic branches of the facial nerve (malar
branches) run across the zygomatic bone to the lateral angle
of the orbit, where they supply the orbicularis oculi, and join
with filaments from the lacrimal nerve and the
zygomaticofacial branch of the maxillary nerve. Injury to
zygomatic nerve causes lagophthalmos.
• Interconnection exist b/w buccal and Zygomatic nerve 70%-
90%.Hence injury may be clinically compensated by these
interconnection.
• Testing- By asking the patient to close the eyes tight.
78. Buccal branch-
• Buccal branches are 2 in no and supplies buccinator.
Upper buccal branch run above the parotid duct.
Lower buccal branch run below the parotid duct.
• Injury to nerve cause difficulty in emptying food from cheek
and impaired ability to smile.
• High degree of arborisation from superior and inferior
division of facial nerve.
• Damage to this nerve less likely result in functional deficit.
• Testing- Ask the patient to puff the cheeks.
79. Marginal mandibular branch-
• Run below the angle of mandible deep to
platysma and superior to facial vein and artery .
• supplies muscle of lower lip and chin.
• Injury result in ipsilateral lack depression of the
lower lip and asymmetry of open mouth smiling
and crying .
• It is connected to other rami in only 15%of
cases.
• Clinical weakness is highly noticed.
• Cervical branch : emerges from apex of
parotid gland ,supply to platysma.
• Testing: Ask the patient to smile
80. Cervical branch-
• The cervical branch of the facial nerve runs
forward beneath the platysma, and forms a
series of arches across the side of the neck
over the suprahyoid region. One branch
descends to join the cervical cutaneous
nerve from the cervical plexus. Also
supplies the platysma muscle.
81. Etiology of facial nerve injury-
Intracranial Intratemporal Extra cranial
Vascular abnormalities
CNS degenerative disease
Tumours of intra cranial cavity
Trauma to the brain
Congenital abnormalities
Agenesis of facial nerve
Bacterial and viral cause
Cholesteatoma
Trauma
Blunt temporal bone trauma
Horizontal and verticle fracture of
temporal bone
Gunshot wound
Tumor invading the middle ear
,mastoid and facial nerve
Iatrogenic
Malignant tumor of parotid gland
Trauma:Laceration, gunshot,
wound
Maxillofacial surgery
Orthognathic ,Tmj ,parotid gland,
other facial esthetic surgery
Preauricular Approach
Submandibular Approach
Retromandibular Approach
83. House Brackmann Grading for clinical evalution
Grade Definition
I Normal Symmetrical function in all areas
II Slight Weakness Noticeable only on close inspection
Complete eye closure with minimal effort
Slight Asymmetry of smile with maximal effort
Synkinesis barely visible , contracture, or spasm absent
III Obvious weakness but not disfiguring
May not be able to lift eyebrow
Complete eye closure & strong but asymmetric mouth movement with maximal effort
Obvious, but not disfiguring synkinesis, spasm or mass movement
IV Obvious disfiguring weakness
Inability to lift brow,Incomplete eye closure & asymmetry of mouth with maximal effort
Sever synkinesis , mass movement , spasm
V Motion barely perceptible
Incomplete eye closure, slight movement corner of mouth
Synkinesis, contracture & spasm usually absent
VI No movement , loss of tone ,no synkinesis,contracture or spasm
84. Testing of the Facial nerve-
• Facial nerve testing includes- Topognostic tests, Prognostic tests and
Intraoperative monitoring-
Topognostic tests- Prognostic tests- Intraoperative
monitoring-
Imaging-
Lacrimation test
Stapedial reflex
Salivary flow test
Test for taste on anterior
two- thirds of tongue
Electromyography
Nerve excitability test
Nerve conduction time
Maximal stimulation test
Electroneurography
Electrically evoked
potential
Mechanically evoked
potential
Computerised
tomography
Magnetic resonance
imaging
85. Topognostic tests-
• Mainly used to determine the site of nerve injury or disfunction. Not
used currently because of unreliable information.
Lacrimation ( Schirmer’s test) A strip of filter paper 5cm x 5 cm is placed on lower conjunctival fornix of each eye for 5
min and the soakage of both sides are comparedwith inhalaltion of ammonia to enhance
lacrimation.
Salivary flow test A polyethylene catheter is introduced into both the Warton’s papillae for 3mm. The amount
of saliva collected is noted over 5 min.
Stapedial reflex Dynamic changes which result from contraction of stapedius in response to stimuli of 500,
1000, 2000, and 4000 Hz, at intensities of 70–115 dB sound pressure level, are measured
and thresholds for activation documented
Taste sensation Not proved to be a useful diagnostic tool.
86. Prognostic tests-
• Two types- orthodromic conduction tests (nerve stimulated proximally
and muscle response recorded distally)and antidromic conduction tests
(nerve stimulated in a retrograde manner)
Elecromyography Records electrical potential generated by muscle cells when these cells are electrically or
neurologically activated
Nerve excitability test Performed by stimulating nerve at stylomastoid foramen and then determining subjectively
the presence of twitch response in facial musculature
Nerve conduction velocity Electrodes are placed along nerve to measure the velocity
Maximal stimulation test Nerve is excited using maximal stimulation and presence of twitch response noted.
Electroneurography Bipolar electrodes deliver an impulse to the FN at the stylomastoid foramen
Summation potential is recorded by another device
87. Intra operative monitoring-
• Intra operative monitoring of the facial
nerve is done using nerve monitors.
• Goals- Early identification of nerve
• Warning the surgeon of nerve involved
in tumour
• Mapping the course of the nerve
• Reducing the mechanical trauma during
operative procedures
• Evaluation and prognosis of facial nerve
function
88. Facial nerve palsy
• Facial paralysis is a devastating
condition where the muscles of facial
expression are paralyzed
• Lack of facial expression is not an
aesthetic issue, but a profound
functional disability because the
function of the face is to communicate.
89. Types-
Upper Motor Neuron Lesion:-
only lower part of face affected
Receives cortico nuclear fibers from the motor
cortex of both the right & left sides.
Lower Motor Neuron Lesion:-BELL’S PALSY
Complete facial half affected
Receives cortico nuclear fibres only from
opposite cerebral hemisphere
90. Bells Palsy-
• Most frequent type of facial nerve palsy.
• Definition “ acute idiopathic lower motor
lower motor neuron palsy of the facial nerve
that is unilateral, self limiting, non
progressive, non life threatening and
spontaneously remitting after 4-6 months
and mostly after 1 year.
• Mostly diagnosed by exclusion and
theoretically considered to be accurate only
when there is no evidence of other cause of
facial palsy.
91. Etiology-
• Anatomical variation of the fallopian canal
• Cold/ viral prodrome- due to herpes simplex
virus or a rising titre to Herpes zoster
• Primary ischemia- Vasospasm - edema and
congestion of the facial nerve- Reversible with
medical treatment
• Secondary ischemia- Pressure from the fallopian
canal- edema and congestion of the nerve in long
term and reversible with medical treatment and
might need decompression surgery
• Tertiary ischemia- thickening of the nerve sheath
with formation of fibrous band or bands. This can
lead to residual palsy. Facial nerve decompression
required.
92. Clinical features-
• Pain in the post auricular region which begin as a deep seated ache
and progresses t severe catch in the upper part of the neck in the
ipsilateral side
• Soap getting into the ipsilateral eye and inability to gargle while
washing face and deviation of face to the opposite side.
• Palsy is acute in onset and unilateral with associated numbness and
streatching of the side of the face involved.
• Can have a history of viral prodrome or history of familial palsy.
• Dereased lacrimation or salivation in the side of the face. Epiphora,
devaitaion of face, dribbling of saliva, collection of food in the
cheek.
• 90% of cases show absent stapedial reflex and chorda tympanic
nerve appear red on otoscopic examination
• Bells phenomenon- Upward movement of eyeball in attempting to
close one eye.
93. Management-
Managements of the Bells palsy can be divided into-
• Medical management
• Surgical management
• It is seen that almost 1/3rd of the patients with incomplete
palsy show an evidence of recovery with medical management
within 3 weeks and eventually progress to complete recovery.
The protocol is to start with medical line of managements as
soon as possible, and monitor the progress using serial EMG
and Nerve Excitability Test repeated evey week. Acoustic
reflex monitoring is to be performed weekly, since it is the first
sign of return of nerve function.
94. Medical management-
• High dose of steroids, starting with presdnisolone-
1mg/kg/day or 60 mg given orally in tapering
doses over a period of 3 weeks
• Antivirals- Vancyclovir- 3000 mg/day
• Combination f corticosteroid and antiviral therapy-
prednisolone (60 mg/day) for 10 days and
Vancyclovir ( 3000 mg/ day) for 7 days
• Vasodilators like Xanitol nicotinate
• Ascorbic acid
• Multi vitamins- Vit B1 B6 and B12
• Eye taping
• Passive physiotherapy
• If there is no improvement with 3 weeks of
medical managemnt, advocate surgical therapy.
95. Surgical management-
• Decompression of the facial nerve by-
- middle cranial fossa approach
- translabyrinthine approach
- transmastoid extra labyrinthine approach
- total decompression by combination approaches
Marsh and Coker Criteria (1991) state the following
indications for the surgical treatment of Bells Palsy-
• Complete denervation
• Paralysis of more than 4-6 weeks
• Incomplete return of function in 60 days
• Recurrent facial palsy
• Nerve excitability test sows a difference of 3.5 mA
on both the sides
96. Surgical decompression of facial nerve-
• The facial nerve, in patients with Bell’s palsy shows “skip
lesions”, i.e segments of normal nerve tissue in between areas of
pathology.
• Decompression of the nerve is mostly carried out in the
tympanic and mastoid segments
• Transmastoid approach via posterior tympanotomy is the most
common method.
• A standard post auricular incision is taken with an anteriorly
based pedicled flap. A complete cortical mastoidectomy is done
and a posterior tympanoplasty is performed.
• Facial nerve is then decompressed and while compressing it is
important that more than half of its circumference is to be
decompressed to achieve good results.
• The fibrous bands around the nerve sheath are then cut and nerve
is separated from the band thus relieving the strangulating effect
97. Facial palsy in infections-
• The infections that can ause facial palsy include-
• Acute suppurative otitis media (ASOM)
• Acute mastoiditis
• Chronic supprative otitis media
Cholesteatoma
Granulations
Tuberculous otitis media
Aural polyp
Tympanosclerosis
• Malignant otitis externa
• Herpes zoester
• Otogenic abcess
98. Facial nerve in temporal bone fracture-
• Temporal bone fractures are extremely common with head
injuries.
• They present with a variety of symptoms including facial
nerve paralysis, hearing loss, vertigo, and leakage of CSF.
• The fracture of the temporal bone can be classified depending
on the relationship of the fracture line to the long axis of the
petrous part of the temporal bone as
- longitudal
- transverse
- mixed
The facial nerve is rendered functionless either temporarily or
permanently in longitudal fractures whereas the risk of
permanent facial nerve palsy is much more in transverse
fractures.
Kettel (1950) believed that immediate paralysis should be
explored as soon as patients condition permits.
The facial paralysis may ne due to-
• An incomplete or complete
transection of facial nerve
• Bony fragments compressing the
nerve
• Edema of the nerve a part of
generalized inflammation
• Compression due to bands formed
in nerve sheath which is caught in
between fragments of bone
99. Clinical features-
• Deafness- Conductive, sensoneural or mixed
• Hemotympanum and bleeding from ear
• Facial palsy
• Vertigo- sever in nature but subsides on its own in 2
weeks
• Lateral rectus palsy- Usually on the opposite side of
fracture due to intra orbital hematoma secondary to
contrecoup brain injury
• CSF otorrhoea
• Discoloration of skin over mastoid: Battle’s sign
• Unconciosness and neurological defecit
100. Management-
• HRCT of temporal bone is the investigation of choice.
• In facial nerve palsy, the facial nerve sheath may be caught in between
the fractured segments. Bands will be formed between the segments
which strangulates the nerve.
• The process of nerve exploration is to be done within 72 hours or
Wallerian degeneration sets in. Firstly, the hematoma is to be
evacuated from the mastoid antrum. Then the facial nerve is
visualized the facial nerve is decompressed all along the length. If
required, the facial nerve can be lifted out of the canal followed by
widening of the canal can be done.
101. Facial nerve in the parotid gland-
• The facial nerve emerges from the stylomastoid foramen (3-4 mm deep to the outer edge
of bony EAC), runs anteriorly, inferiorly and laterally to enter the posteromedial aspect
of the parotid gland.
• The nerve bisects it unequally into a large part, which lies lateral to the nerve called the
superficial lobe and a smaller part medial to it called the deep lobe.
• Landmarks within the parotid- the different methods to locate the nervein the parotid
gland are-
o Tragal point of Conley- Nerve is located medial and 1 cm inferior to the tragal cartilage
o Styloid process- The nerve passes lateral to the styloid process at the skull base
o Temporal branch is located by a line from tragus to lateral canthus
o Buccal branch located by a line drawn from tragus towards the alae of nose parallel to
the zygoma but 1 cm below
o Marginal mandibular branch near the angle of mandible at a point 4- 4.5 cm from the
attachment of the lobule of the pinna
102. The nerve divides into two main divisions, one cm
beyond its entry into the parotid gland at the pes
ansarinus-
1. Upper division is stouter and consists of the
zygomatic, temporal, and buccal branch
2. Lower division is thinner and consists of
submandibular and cervical branches.
Following are the anatomic variations of the facial
nerve that occur in the face-
1. Variation in the branching pattern
2. Formation of a loop due to the anastomosis
between the facial nerve, which can be short, long
or multiple
3. Plexiform communications between various
branches of the facial nerve
4. Branches of facial nerve can pass through the
clefts in superficial veins and nerve loops can be
formed over the veins
103. Involvement of facial nerve in relation to
parotid-
• The facial neve can be damaged in the
following lesions involving the parotid
gland-
• Trauma- Penetrating trauma, lacerations,
crushing, tearing, compression
• Neoplasm- Pleomorphic adenoma,
lymphangiomas etc
• Trauma during surgeries like superficial
parotidectomy
• Malignancy
104. Injury to facial nerve in parotid and its repair-
• Injury to the main trunk or temporozygomatic or cervicofacial divisions
is always repaired
• In clear lacerations with immediate onset of facial palsy, repair is
undertaken in the first 3 days or if not possible, three weeks later
• In case of gross contamination, proximal and distal segments should be
identified and tagged
• Primary end to end anastomosis results in greater functional return then
interposition grafting with multiple anastomosis
• In parotid surgery, when facial nerve is to be preserved, it is stimulated
near the stylomastoid foramen before wound closure if there is no
movement then careful inspection under microscope is carried out for
evidence of injury like accidental ligature on nerve crush injury
• When facial nerve injury occurs posterior to the anterior margin of
masseter, concomitant injury to the parotid duct is looked for.
106. Seckel’s danger zones-
Danger zone 1-
• The area where the great auricular nerve emerges from beneath
the sternocleido mastoid muscle, becomes more superficial and
thus is susceptible to injury.
• It is a circle of radius 3 cm drawn around a point in the middle
of the SCM belly 0.6 cm below the caudal edge of the EAC
Danger zone 2-
• The temporal branch of the facial nerve runs under the temporo
parietal fascia- SMAS layer, having emerged from beneath the
parotid gland at the level of zygoma on its way to innervate the
frontalis muscle in the forehead
• Outlined by drawing a line 0. cm below the tragus to a point 2
cm above the lateral eyebrow, drawing a second line to the
zygoma to the lateral orbital rim and connecting these two lines
by a third line
107. Facial danger zone 3-
• This zone contains the marginal mandibular branch of the facial nerve at a point in
its course where it is most vulnerable as the platysma- SMAS layer thins below and
the nerve courses superiorly to innervate the depressor anguli oris muscle.
• Described by drawing a point on the middle of the mandibular body2 cm posterior
to the oral commissure and drawing a circle with radius 2 cm around this point.
Facial danger zone 4-
• This zone contains the zygomatic and buccal branches of the facial nerve that are
superficial to and rest on the Buccal Pad of Fat.
• Outline by placing a point on the highest point of the molar eminence, another
point on the mandibular angle and a third point on the oral commissure. These
three points are connected to form a triangle
108. Facial danger zone 5-
• Contains supra orbital and supra trochlear nerve which both are the branches of the
first division of trigeminal nerve.
• The supra orbital foramen is palpated and a line is dropped through the mid pupil
and the second mandibular premolar. The area is marked with a circle drawn with a
radius of 1.5 cm on this line centred on the supra orbital foramen.
Facial danger zone 6-
• It contains the infra orbital nerve, which is a second part of the trigeminal nerve.
• Described by a circle with 1.5 cm radius around the infra orbital foramen, which
lies 1 cm below the infra orbital rim along a line drawn through the mid pupil and
the second mandibular premolar.
109. Facial danger zone 7-
• It contains the mental nerve which is a sensory branch of the trigeminal
nerve.
• Described by a circle with the radius of 1.5 cm around the mental foramen,
which lies on the mid mandible below the second mandibular premolar
along the line drawn through the supra orbital foramen, mid pupil and the
infra orbital foramen.
110. Anatomical points-
These measurements can be used to identify the main
trunk and also to avoid it.
Clinically visible Length of Facial Nerve trunk 1.3cm
Point of bifurcation-
• From lowest point of External bony Auditory Meatus
to the Bifurcation 1.5- 2.8cm*
Mean 2.3 +_ 0.28cm
• From Lowest point of the post-glenoid tubercle to
the bifurcation 2.4- 3.5 cm
Mean 3.0+_ 0.3 cm
• The temporal nerve 0.8- 3.5 cm from anterior
concavity of the external auditory canal.
111. Alkayat and Bramley Incision-
The incision is question mark-shaped and begins about a pinna's length
away from the ear, antero-superiorly just within the hair line and curves
backwards and downwards well posterior of the main branches of the
temporal vessels till it meets the upper attachment of the ear.
The pre auricular incision is placed always with 0.8 cm from the anterior
border of external auditory canal to prevent injury to the temporal nerve
112. Protection of Marginal mandibular nerve-
According to Ziarah and Atkinson-
• Distance between mandibular branch & the lower border of
mandible -1.2cm.
• 53% of Mandibular branches run below the inf border of
mandible before reaching the facial vessels .
• 6% continued below the level of mandible for up to a further
1.5cm before turning upward and crossing the mid line
• 21% of cases cervical nerve emerged as a single branch,
travelled posterior to gonion at variable distance 1.4cm
• Remaining 20% nerve emerged as 2 closely related and
running parallel
113. Prevention of facial nerve injury submandibular approach
• For marginal Mandibular branch
Incision is placed 1.5-2cm below the lower
border mandible.
located close/within the superficial layer of
deep cervical fascia.
• For Cervical branch –
Incision at Angle must lie at 3cm distance.
Mandibular notch -4cm below the body of the
mandible
114. Treatment
General -
Reassurance
Relief of Ear pain with analgesics
Eye Care
Physiotherapy or massage of Facial muscles
Medical Management –
Steroids
Vasodilators
Vitamins
Mast cell inhibitors
Anti histamine drugs
Surgical Treatment-
115. Surgical treatment
• The ultimate goal is to restore independent, and spontaneous facial
expressions
• Age of the patients, duration of facial paralysis, condition of facial
musculature, status of potential donor nerves and muscles all these
will influence the treatment options.
• A-Acute injury (<3wks)
• B- Intermediate Duration( 3weaks- 2years)
• C- Late ( > 2years)
118
116. Facial nerve grafting-
• Great auricular nerve
– 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
117. Treatment options - Iatrogenic injury
• If transected during surgery
– Explore 5-10mm of the involved segment
– Stimulate both proximally and distally
• Response with 0.05mA = good prognosis; further exploration not required
• If only responds distally = poor prognosis, and further exposure is warranted
• If loss of function is noted following surgery, wait 2 -3 hr and then re-evaluate
the patient.
For anesthetic to wear off
• Waited time and still paralysis
118. • Unsure of nerve integrity – re-explore as soon as possible
• Integrity of nerve known to be intact
High dose steroids – prednisone at 1mg/kg/day x 10 days
then taper.
72 hours : ENoG to assess degree of degeneration
» >90% degeneration – re-explore
» <90% degeneration – monitor
• If worsening paralysis occurs re-explore
• if no regeneration, but no worsening, timing of exploration or whether
to is controversial
119. Take home message-
• The trigeminal nerve and facial nerve, being the most important nerves
of the face require special attention during any maxillofacial surgical
procedure.
• The proper knowledge of anatomy, use of modern technologies and
modified incisions can be useful in preventing the nerve damage.
• Proper diagnosis and evaluation of the patient are the most important
factors governing the outcome of treatment of nerve damage
• Any successful nerve repair depends on factors like timing, surgical
technique, type of graft and nature of the injured nerve
120. References-
• Youngmans and Winn neurological surgery- 7th Edition
• Katusic S, Williams DB, Beard CM, et al. Epidemiologynand clinical features of idiopathic trigeminal
neuralgia and glossopharyngeal neuralgia: similarities and differences, Rochester, Minnesota,
1945-1984. Neurepidemiology. 1991;10:276-281.
• Handbook of neurosurgery by Mark S Greenberg
• Headache Classification Subcommittee of the International Headache Society. The international
classification of headache disorders. 2nd ed. Cephalalgia. 2004;24(suppl 1):9-160.
• Jannetta PJ. Neurovascular compression in cranial nerve and systemic disease. Ann Surg.
1980;192(4):518-525
• Handbook of local anesthesia by Stanley F Malamed- 6th edition
• Atlas of surgery of the facial nerve by DS Grewal
• Pubmed search
• Science direct topics
Secretomotor fiber come from the grater petrosal nerve
Terminal branches (exit through the infraorbital foramen)
Inferior palpebral
Lateral nasal
Superior labial
Recently, however, mention has been made of the potential toxicity of a 4% solution of articaine hydrochloride when used for local anesthetic nerve blocks for dental procedures*
for all injuries per thousand M3s removed were
neurologic deficit such as loss of corneal reflexes, anesthesia, paresthesia, muscular atrophy or weakness, etc.
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 .
Injury to buccal nerve cause difficulty in emptying food from cheek and impaired ability to smile
