Seminar presented by :- Serene Batra, MDS 1styr [batch of

2010].Dept of Oral & Maxillofacial Surgery,

B.R.S Dental College ,Sultanpur,Panchkula

ContentsContents Introduction Development Composition of facial nerve-types of fibres Nuclei i.r.t facial nerve Central connections of facial nerve Facial nerve-segmental description Course anatomy Branches of communication Branches of distribution Ganglia i.r.t facial nerve Course anomalies Surgical anatomy & surface landmarks Nerve injury-sunderland’s classification Facial paralysis Syndromes assosciated with facial nerve Other conditions assosciated with facial nerve References

INTRODUCTION

INTRODUCTIONThe facial nerve is a nerve which controls the muscles on the side

of the face. It allows us to show expression, smile, cry, and wink. Injury to the facial nerve causes a socially and psychologically devastating physical defect; treatment may require extensive rehabilitation or multiple procedures.

The facial nerve is the seventh of the twelve CRANIAL NERVE.

Facial Nerve is a mixed nerve consist of Large motor root called as FACIAL NERVE PROPER and a small sensory root called as NERVUS INTERMEDIUS.

The facial nerve is composed of approximately 10,000 neurons, 7,000 of which are myelinated and innervate the nerves of facial expression. Three thousand of the nerve fibers are somatosensory and secretomotor and comprise the nervus intermedius.

DEVELOPMEDEVELOPMENTNT

DEVELOPMENTDEVELOPMENT

Facial Nerve developed from 2nd branchial arch.

Facial nerve course, branching pattern, and anatomical relationships are established during the first 3 months of prenatal life

The nerve is not fully developed until about 4 years of age

The first identifiable FN tissue is seen at the third week of gestation-facioacoustic primordium or crest

Facial Nerve Embryology-4th WeekBy the end of the 4th week, the facial and acoustic

portions are more distinct.The facial portion extends to placodeThe acoustic portion terminates on otocyst

Facial nerve embryology: 5th Week

Early 5th week, the geniculate ganglion forms

- Proximal portion of premordium becomes less cellular and more fibrous

- Distal portion:

- Distal part of primordium separates into 2 branches: main trunk of facial nerve and chorda tympani

- 1-caudal course into 2nd pharyngeal arch Main trunk of facial nerve.

2- curves rostrally into 1st arch chorda tympani.

Facial nerve embryology: 7th weekEarly 7th week, geniculate ganglion is well-

defined and facial nerve roots are recognizableThe nervus intermedius arises from the ganglion

and passes to brainstem. Motor root fibers pass mainly caudal to ganglion.

Facial Nerve Embryology : 8th Week

By 8th wk it has joined with DEEP petrosal nerve.

Nerve to stapedius seen by 8th week

Early 8th week,temporofacial and cervicofacial divisions

Late 8th week, 5 major peripheral subdivisions present

Fibers Associated With Facial Nerve

Special Visceral Efferent –Branchial Motor FibersPremotor cortex motor cortex

corticobulbar tract bilateral facial motor nuclei (pons) facial muscles

Stapedius, stylohyoid, posterior digastric, buccinator

General Visceral Efferent/ParasympatheticSuperior salivatory nucleus (pons) nervus

intermedius greater/superficial petrosal nerve facial hiatus/middle cranial fossa joins deep petrosal nerve (symp fibers from cervical plexus) thru pterygoid canal (as vidian nerve) pterygopalatine fossa spheno/pterygopalatine ganglion postganglionic parasympathetic fibers joins zygomaticotemporal nerve(V2) lacrimal gland & seromucinous glands of nasal and oral cavity

Superior salivatory nucleus nervus intermedius chorda joins lingual nerve submandibular ganglion – postganglioic parasympathteic fibers submandibular and sublingual glands

Special Visceral Afferent/TastePostcentral gyrus nucleus solitarious–

nervus intermedius geniculate ganglion – chorda tympani joins lingual nerve anterior 2/3 tongue, soft and hard palate

General Sensory Afferent/Sensory

Sensation to auricular concha, EAC wall, part of TM, postauricular skin

Cell bodies in geniculate ganglion

Brancial motorBrancial motor(special (special visceral visceral efferent) efferent)

Supplies the muscles of facial Supplies the muscles of facial expression; posterior belly of expression; posterior belly of digastric muscle; stylohyoid, digastric muscle; stylohyoid, and stapedius. and stapedius.

Visceral motorVisceral motor(general (general visceral visceral efferent) efferent)

Parasympathetic innervation of Parasympathetic innervation of the lacrimal, submandibular, the lacrimal, submandibular, and sublingual glands, as well and sublingual glands, as well as mucous membranes of as mucous membranes of nasopharynx, hard and soft nasopharynx, hard and soft palate. palate.

Special Special sensorysensory(special (special afferent) afferent)

Taste sensation from the Taste sensation from the anterior 2/3 of tongue; hard anterior 2/3 of tongue; hard

and soft palatesand soft palates. .

General General sensorysensory(general (general somatic somatic afferent) afferent)

General sensation from the General sensation from the skin of the concha of the skin of the concha of the auricle and from a small area auricle and from a small area behind the ear. behind the ear.

Nuclei Associated With Facial Nerve

Nuclei i.r.t Nuclei i.r.t facial nervefacial nerve

Motor nucleus of facial nerve

Superior salivatory nucleus

Nucleus of tractus solitarius

Nucleus of spinal tract of the trigeminal nerve

1.Facial nerve nucleus[motor]1.Facial nerve nucleus[motor] Location: deep in the reticular

formation of the caudal part of pons,below and in front of abducent nucleus

The motor nucleus represents SPECIAL VISCERAL EFFERENT FIBERS( Branchial)

It presents the following nuclear sub-groups

1. LATERAL 2. INTERMEDIATE 3. MEDIAL- a. Dorso-medial b. Ventro-

medial (BY-CARPENTER,1978)

Fibers from motor nucleus pass dorso-medially towards the caudal end of the abducent nucleus,and then run rostrally superficial to that nucleus occupying the FACIAL COLLICULUS of the floor of FOURTH VENTRICLE.

At the cranial end of abducent nucleus the fibers bend abruptly downwards and forwards forming an INTERNAL GENU and emerge from lower border of pons through motor root

Other nuclei.Other nuclei.2.Superior salivatory nucleus: It lies dorsomedial to the facial

nucleus. It represents General Visceral Efferent Column. It gives origin to preganglionic secreto-motor fibers which emerge through sensory root

3.Nucleus of tractus solitarius: I t represents Special Visceral Affrent column.primary terminal taste centre . fibres through chorda tympani and from the soft palae through greater petrosal nerve

.4.Nucleus of spinal tract of the trigeminal nerve. It recieves

cutaneous sensations from the auricle through the auricular branch of vagus nerve

NEURONS1- Upper motor neuron: Primary

motor cortex (Precentral gyrus)The axons of these neurons

enter the Corticonuclear fiber bundle to reach the second lower motor neuron in the Pons.

2- Lower motor neuron: Facial motor nucleus.

The facial nucleus is divided into two parts:

The upper part receives bilateral innervations, and supplies the muscles of the forehead and eyebrows (temporal branches).

The lower part receives innervations mainly from the contra lateral hemisphere, and supplies the muscles of the lower part of the face through the facial nerve.

Central connections of the facial nerveCentral connections of the facial nerve

CROSBY AND DEJONGE, ALONG WITH NELSON, have provided two of the most complete descriptions of the facial nerve's central connections

Cerebral cortex: voluntary responses arise from pre & post central gyri.

Corticobulbar tract: discharges from facial motor cerebral area are carried through its fascicles to the internal capsule, thence through upper midbrain & on to the pontine facial nucleus.

The tracts from upper face cross & recross en route to pons, while those of lower face cross only once. descending corticofacial fibres innervate LMN region bilaterally but with contralateral predominance, whereas UMN receive scant direct cortical innervation on either side of brain.

. In 1987, Jenny and Saper performed an extensive study of the proximal facial nerve organizations in a primate model.3 They demonstrated

UMN & LMN lesions and their clinical co-relation to corticobulbar tract course UMN & LMN lesions and their clinical co-relation to corticobulbar tract course & the regions of face affected.& the regions of face affected.

In 1987, Jenny and Saper performed an extensive study of the

proximal facial nerve organizations in a primate model.They demonstrated that the descending corticofacial fibers innervated the lower facial motor nuclear region bilaterally but with contralateral predominance. The upper facial motor nuclear regions received scant direct cortical innervation on either side of the brain

Extrapyramidal system The extrapyramidal system consists of the basal ganglia and

the descending motor projections other than the fibers of the pyramidal or corticospinal tracts. This system is associated with spontaneous, emotional, mimetic facial motions.

Lower midbrainA lesion in the lower midbrain above the level of the facial

nucleus may cause contralateral paresis of the face and muscles of the extremities, ipsilateral abducens muscle paresis (due to effects on the abducens nerve), and ipsilateral internal strabismus . If the lesion extends far enough laterally to include the emerging facial nerve fibers, a peripheral type of ipsilateral facial paralysis might be apparent.

Pons 

The facial motor nucleus is located in the lower third of the pons beneath the fourth ventricle. The neurons leaving the nucleus pass around the abducens nucleus as they emerge from the brain stem

SYNDROMES

LOCATION OF LESION

CHARACTERSTICS FEATURES

Foville syndrome Lateral pons Ipsilateral facial paresis, ipsilateral facial analgesia, ipsilateral Homer syndrome, ipsilateral deafness

Meige syndrome Basal ganglion Facial dystonia

Millard-Gublersyndrome

Pontine nucleus Unilateral sixth nerve palsy, ipsilateral seventh nerve palsy, contralateral hemiparesis 4

Moebius syndrome

Fundus of IAC to facial hiatus Ipsilateral facial paresis, ipsilateral abducens (CN VI) palsy

Parkinson disease Extrapyramidal pathways Masked facies

Pseudobulbar palsy

Pontine Bilateral facial paresis with other CN defects, hyperactive gag reflex, hyperreflexia associated with hypertension, emotional lability

Weber syndrome Upper midbrain Ipsilateral loss of direct and consensual pupillary light reflexes, ipsilateral external strabismus, oculomotor paresis

Gangalia Associated With

Facial Nerve

Ganglia related to facial nerve.SphenopalatineSubmaxillaryOtic Ciliary

Sphenopalatine ganglion. Deeply placed in the

pterygopalatine fossa, close to sphenoplatine foramen.

Triangular/heart shaped, reddish gray in colour.

Sensory root: two sphenopalatine branches of maxillary nerve

Motor root: from nervus intermedius,through greater superficial petrosal nerve.[sympathetic efferent, preganglionic.].

Sympathetic root: derieved from carotid plexus through deep petrosal nerve.

Motor + symathetic root : nerve of pterygoid canal.

Submaxillary ganglionSituated above the deep portion of the maxillary

gland, on the hyoglossus,, connected to & suspended from lingual nerve, as a small fusiform ganglion.

Efferent preganglionic sympathetic fibres from superior salivatory nucleus via chorda tympani nerve.

Post ganglionic fibres: to the submaxillary gland.

Communication: with the sympathetic plexus around the external maxillary artery.

Branches of distribution: 5-6, from lower part of ganglion, supplying the mucous membrane of mouth,duct of submaxillary glands; via lingual nerve to the sublingual gland.

Otic ganglion Small oval flattened structure lying just below the foramen ovale; medial

to mandibular nerve.

Relations: lateral– mandibular n trunk. medial-origin of tensor palatini muscle. posterior- middle meningeal artery.

Branches of communication: 1. pterygoid internus n. [motor & sensory root. Q.] 2. glossopharyngeal & facial n. through lesser petrosal n. – root from

glossopharyngeal, motor root from facial n. 3. sympathetic root from middle meningeal artery. Preganglionic fibres from via glossopharyngeal from infr salivary/dorsal

nucleus. Postganglionic with auriculotemporal n. to the parotid gland. slender filaments to n. of pterygoid canal & chorda tympani.

Branches of distribution: tensor veli palatini, tensor tympani.

Ciliary ganglion Small, sympathetic, about a pinhead’s size.

Situated at the back of orbit, in loose fat b/w optic n. & rectus lateralis muscle.

Roots: sensory: from nasociliary n. motor: from branch of oculomotor nerve sympathetic: cavernous plexus

- Branches of communication from sphenopalatine ganglion.

Branches: short ciliary nerves to the ciliaris muscle, cornea and iris.

Course anatomy- Facial nerve segments:-Course anatomy- Facial nerve segments:-

Intracranial segment:- supranuclear & brainstem parts.

Meatal segment:- [13-15mm] from brainstem to internal acoustic meatus. Here nerve lies anterior & superior to VIII cranial nerve components.

Intratemporal part:- (a) Labyrinthine segment:- [3-4mm] narrow part from

fundus of IAC to facial hiatus. Common site of pathology, temporal bone fracture etc.

(b) Tympanic segment:- [8-11mm] geniculate ganglion to pyramidal turn.

(c) Mastoid segment:- [10-14mm] pyramidal process to stylomastoid foramen.

Extracranial segment:- [15-20mm] stylomastoid foramen to pes anserinus [goose foot].variable branching patterns on face.

Intracranial course anatomy.Intracranial course anatomy.Sensory & motor roots.Sensory & motor roots.

Motor root: < lies: deep in reticular formation of lower pons. above the nucleus ambiguus,

behind superior olivary nucleus, medial to nucleus of spinal tract of trigeminal nerve.thence courses in the substance of pons.

< carries: somatic fibres to muscles of scalp, auricle, buccinator,platysma,stapedius, stylohyoideus,posterior belly of digastric; preganglionic sympathetic motor/vasodilator fibres to submaxillary & sublingual glands.

< course: goes back & medially,reaches posterior end of abducent nucleus,then runs up close to the midline beneath colliculus fasciculus,takes a second bend at the antr end of abducent nucleus,then runs down & forward through pons to emerge between the olive & inferior peduncle.

Sensory root: [nervus intermedius/pars intermedii of wrisberg] arises from the genicular

ganglion. Genicular ganglion: is situated on the geniculum of facial nerve in the facial

canal, behind the hiatus of the canal. It has unipolar cells whose single processes divide in a T shaped manner into

central & peripheral branches. 1.central branches: leave the facial trunk in the internal acoustic meatus to

form the sensory root. 2.peripheral branches: continue into chorda tympani & greater superficial

petrosal nerve.

Course segments of the facial nerve (contd…)

Meatal part: from their superficial attachments to the brain,the two roots of the facial nerve pass lateral & forward with the acoustic nerve to the internal acoustic meatus. In the meatus, motor root lies in a groove on the upper & anterior surface of the acoustic nerve, while the sensory root lies in between. [hence the name nervus intermedius].

Intratemporal part:

facial nerve enters the facial canal at the bottom of the meatus. It moves laterally b/w the cochlea & vestibule towards the medial end of the tympanic cavity,then bends suddenly backwards & arches downwards, behind the tympanic cavity, towards the stylomastoid foramen.(second genu).

Extratemporal part: on emerging from the stylomastoid foramen, facial nerve runs forward in the substance of parotid, crosses the ECA, & divides behind the ramus of mandible into branches from which offsets are distributed over the side of face, head, upper neck etc, supplying the muscles of this region. These branches & offsets unite to form the parotid plexus.

Greater superficial petrosal nerve

Arises from genicular ganglion.

Consists of sensory branches from mucous membrane of soft palate & few motor fibres to form the motor root of sphenopalatine ganglion.

Passes forward through hiatus of facial canal.

Runs in a sulcus on anterior surface of petrous temporal bone beneath the semilunar ganglion.

Moves to the foramen lacerum, where it is joined by deep petrosal nerve, to form the nerve of pterygoid canal which ends in sphenopalatine ganglion.

Branches of distribution In the facial canal: N. to stapedius chorda tympani

At exit from SMF: posterior auricular digastric stylohyoid

On the face: temporal zygomatic buccal mandibular cervical

Within facial canal.

N. of stapedius: arises opposite the pyramidal eminence & passes through a small canal in this eminence to reach stapedius muscle.

Chorda tympani nerve: Arises: from facial nerve as it passes down

behind the tympanic cavity, about 6mm above SMF.

-Runs upward & forwards in a canal enters tympanic cavity through an aperture on its posterior wall [close to medial surface of tympanic membrane, and on a level with upper end of manubrium of the malleus].

-Transverses the tympanic cavity b/w fibrous & mucous layers of the membrane.

Crosses the manubrium of the malleus. -Emerges from tympanic cavity through a

foramen at the inner end of petrotympanic -Receives a small branch from otic ganglion. -Joins posterior border of lingual nerve at an

acute angle. -Receives few efferents from motor root to

enter submaxillary ganglion. -Majority of efferents from to mucous

membrane of anterior 2/3rd of tongue.

At exit from stylomastoid foramen: Posterior auricular nerve: it arises near SMF to run upwards in

front of the mastoid process ,where it communicates with 1.auricular branch of vagus 2.posterior branch of greater auricular n. 3.lesser occipital n.

As it descends b/w external acoustic meatus & mastoid process, it divides into

1.auricular branch: supplies auricularis posterior & internal muscles on cranial surface of auricle.

2.occipital branch: larger, passes back along superior nuchal line of occipital bone.supplies occipitalis.

Digastric branch: arises close to the SMF divides into filaments. Supplies posterior belly of digastric muscle.One filament joins glossopharyngeal nerve.

Stylohyoid branch: often arises in conjunction with digastric branch.its long & slender, & enters stylohyoideus about its middle.

Facial nerve-on the face

Division at about 13mm from SMF

Facial nerve lies in a plane dividing the parotid gland into its deep & superficial lobes.

Two main divisions: temporofacial & cervicofacial

Supplies muscles of the face.

5 main branches on the face: temporal, zygomatic, buccal, mandibular, cervical.

Terminal branches Temporal branches: crosses zygomatic arch into the temporal

region. >supply: auricularis antr & supr >join: zygomaticotemporal branch of maxillary,auriculotemporal branch of mandibular. >more antr branches supply: frontalis, orbicularis oculi,corrugator. >join: supraorbital & lacrimal br of opthalmic. Zygomatic branches: run across zygomatic bone to lateral angle

of orbit >supply: orbicularis oculi >join: filaments from lacrimal branch of

opthalmic,zygomaticofacial br maxillary n.

Buccal branches: larger, pass horizontally forward to be distributed

below the orbit & around the mouth. >superficial branches: run beneath the skin, above the superficial

muscles of face which they supply.some to the procerus. >deep branches: pass beneath the zygoma & quadratus labii

superioris. supply: zygomaticus & quadratus labii superioris,small muscles

of nose. form infraorbital plexus with the infraorbital nerve. <lower deep branches: supply buccinator & orbicularis oris join: filaments from buccinator br of mandibular n.

Mandibular branches: pass forward beneath platysma & triangularis.

supplies muscles of lower lip & chin. communicates with mental br of inferior alveolar n.

Cervical branches: runs forward beneath platysma & supplies it. forms a series of arches across side of neck in suprahyoid

region. one branch descends to join cervical cutaneous n. from

cervical plexus.

Branches of communication of the cranial nerve VII.Branches of communication of the cranial nerve VII. In internal acoustic meatus: with acoustic nerve. Genicular ganglion: 1.with sphenopalatine ganglion via gr.superficial petrosal n. 2.with otic ganglion via a branch joining lesser superficial petrosal n. 3.with the sympathetic plexus on the middle meningeal artery via the external petrosal nerve. Within facial canal: auricular branch of vagus Exit from SMF: 1.with glossopharyngeal n. 2.with vagus n. 3.greater auricular n. [of cervical

plx]. 4.auriculotemporal n .[in the parotid]. In the ear: with lesser occipital n. [behind the ear]. On face: with trigeminal n. branches. In the neck: with the cutaneous cervical n.

Realtion between facial nerve and vestibulocochlear nerve from brainstem to fundus of IAC

Variations in terminal branching pattern

1. Buccal branches from the two main divisions of facial trunk, not from other branches of facial nerve.

2. Buccal branches arising from two main divisions interconnected with zygomatic branch.

3. Marginal mandibular branch gives nerve twigs to buccal branches.

4. Nerve twigs from zygomatic’s marginal mandibular branches merge to buccal branch arising from the two main divisions.

Surgical anatomy & landmarks. Facial nerve at its exit from SMF: [surface anatomy] is situated

2.5cm from the surface, opposite the middle of the anterior border of mastoid process, a horizontal line from this point to the ramus of mandible overlies the stem of the nerve.

Localization of the facial nerve during parotid surgery: 1. Tragal pointer: points to main trunk proximal to Pes, 1-1.5 cm deep &

inferior to the pointer.2. Tympanomastoid suture: traced medially, main trunk of VII lies 6-

8mm deep to suture line.[suture is 6-8mm lateral to SMF].3. Posterior belly of digastric: guide to SMF. Trunk of VII lies just

posterior & superior to cephalic margin of the muscle.4. Styloid process: sits 5-8mm deep to tympanomastoid suture, VII trunk

lies on its posterolateral aspect near its base.5. Main trunk can also be found midway b/w,& 10mm posterior to, the

cartilaginous tragal pointer of external auditory canal & posterior belly of digastric muscle.

6. Retrograde identification along a terminal branch.

Identification of terminal branches: Buccal branch: runs with parotid duct superiorly or inferiorly. [Parotid

duct lies from lower margin of concha to midway b/w red margin of lip & ala of nose, about a finger breadth below the zygomatic arch.

Temporal branch: crosses zygomatic arch parallel to superficial temporal artery & vein. [superficial temporal artery can be followed across posterior end of the zygomatic arch to a point 3-5cm above it, where it divides into frontal & parietal branches.

Frontal branch: lies underneath frontalis, superficial to deep temporal fascia,so dissect deep to subcutaneous plane/fascia.

Marginal mandibular branch: runs along the inferior border of parotid, superficial to the retromandibular vein & lies along along the body of mandible[or 1-2mm below in 20%cases]. It lies deep to platysma through most of the course, but becomes superficial approx 2cm lateral to corner of mouth, & ends on the undersurface of the muscle.

An injury results in paralysis of muscles depressing corner of the mouth

Diagnostic Test Causes of facial nerve disorder vary from unknown to life threatening.

Sometimes, there is a specific treatment for the problem. Accordingly, it is important to investigate why the problem has occurred. The specific tests used for diagnosis will vary from patient to patient, but include:

Hearing tests: Hearing tests are done to assess the status of the auditory nerve. The stapedial reflex test can evaluate the branch of the facial nerve that supplies motor fibers to one of the muscles in the middle ear. 

Balance tests: Will help find out if part of the auditory nerve is involved.

Tear tests: The loss of the ability to form tears may help to locate the site and severity of a facial nerve lesion.

 Taste tests: The loss of taste in the front of the tongue may help locate the site and severity of a facial nerve lesion.

  Salivation test: Decreased flow of saliva may help locate the site and severity of a

facial nerve lesion. 

Imaging studies: help determine if there is infection, a tumor,

a bone fracture, or any other abnormality. These studies are usually a CT scan and/or a MRI scan.

  Electrical tests: Stimulation of the nerve by an electrical current

tests whether the nerve can still cause muscles to contract. It can be used to evaluate progression of the disease. For example, if testing indicates equal muscle response on both sides of the face, the patient can be expected to have complete return of facial function in three to six weeks without significant deformity

Nerve injury-Sunderland’s classification. Class I- neuropraxia: >pressure on nerve trunk, causing conduction block at pressure site. >no disruption of axonal activity or connective elements. >quick complete recovery on removal of pressure. >stimulation of nerve distal to block can propagate impulses when no impulses can cross the

block.

Class II- axontemesis: >more severe injury; wallerian degeneration of axon distal to injury,down to motor end

plate. >connective tissue elements intact, so nerve regenerates on removal of insult. delayed

healing. [1mm/day].

Class III- endoneurotmesis: >severe lesion, disruption of axon & endoneurium, wallerian degeneration occurs. >incomplete recovery on regeneration,because the axons regenerate into wrong/no

endoneurium.

Class IV- perineurotmesis: >disruption of axon, endoneurium & perineurium. >greater chance of abberant regeneration than in class III injury.

Class V- epineurotmesis: >disruption of axon as well as connective tissue elements. >no chance for regeneration unless transected ends are surgically re approximated.

House- Brackmann facial nerve grading system.Grade Description CharacteristicsI Normal Normal facial function in all areas

II Mild dysfunction Slight weakness noticeable on close inspection; may have very slight synkinesis

III Moderate Obvious, but not disfiguring, difference dysfunction between 2 sides; noticeable, but not severe, synkinesis, contracture, or hemifacial spasm; complete eye closure with effort

IV Moderately severe Obvious weakness or disfiguring asymmetry; dysfunction normal symmetry and tone at rest; incomplete eye closure

V Severe dysfunction Only barely perceptible motion; asymmetry at rest

VI Total paralysis No movement

Clinical & anatomic features of facial nerve damage.

Facial paralysis

Etiology:

Idiopathic: bell’s palsy.Traumatic: parotid tumours, facial n

schwannomas,acoustic neuromas, brainstem tumours.Inflammatory: herpes zoster, lyme ds[borreliosis] ,

parotitis, otitis media, mastoiditis, EBV, poliomyelitis, basilar meningitis, sarcoidosis, TB, coxsackie, mumps, HIV, leprosy etc.

Congenital: Mobius synd, I/U trauma, perinatal intracranial bleed.

Other suggested etiology:

Genetic [myotonic dystrophy],Metabolic

[hypothyroid,hyperparathyroid,osteopetrosis,diabetes mellitus],

Vascular, cleidocranial dysostosis, melkerson rosenthal synd, MS, myasthenia gravis.

Causes of unilateral palsy: cerebellopontine

angle tumour, HZV,bell’s palsy, trauma, surgery related, CULLP.contralateral with UMN lesion.

Causes of bilateral palsy: brainstem stroke, contusion, glioma, myotonic dystrophy, mobius synd, myasthenia gravis, guillain barre synd, autoimmune demyelination, miller fischer synd, melkersson rosenthal synd, sarcoidosis, lyme disease.

Syndromes associated with facial paralysis. Mobius syndrome: aplasia of VII nerve nuclei in brainstem [defect

on chromosome 3q], often accompanied by bilateral VI n. palsies, palatal & lingual palsies, deafness, deficiency of pectoral & lingual muscles, extremity defects.

Melkersson Rosenthal syndrome: recurrent facial palsy, orofacial edema, fissured tongue.begins in teens. etiology unknown.

Ramsay Hunt syndrome: herpes zoster of VII, esp genicular ganglion, presenting as unilateral VII palsy, severe otalgia, vescicular eruptions on involved side.poorer prognosis.

Goldenhar’s synd: oculoauriculovertebral dysplasia. Defects of I & II branchial arch structures. Anomalies include auricular deformities, preauricular tags,EAC atresia, ossicular malformations, VII n. hypoplasia, absent chorda tympani, colobomas, vertebral anomalies.

Guillain Barre synd: autoimmune disorder causing acute inflammatory demyelinating neuropathy..ascending motor weakness with involvement of other cranial nerves,I,III,IV,VI. Opthalmoplegia, paraesthesiae.

variants: 1.Miller Fischer syndrome.

2.chronic inflammatory demyelinating neuropathy.

CULLP: congenital unilateral lower lip palsy.defect limited to absent depressor labii inferioris activity.

Meihlke synd: thalidomide embryopathy. Microsomia, cr n VI,VII involvement.

Heerfordt synd / Uveoparotid fever: form of sarcoidosis.

Bell’s palsy. Definition: Acute, idiopathic, unilateral facial paresis or paralysis

in a pattern consistent with peripheral facial nerve dysfunction, which maybe partial or complete; occuring with equal frequency on the right & left sides of face.

Etiology: vascular causes, herpes viruses, inheritance. Additional symptoms: otalgia, oropharyngeal/facial numbness,

impaired tolerance to ordinary noise levels, taste disturbances. Prognosis: fair to good. signf improvement within 3 weeks to

months. full recovery in 70% cases. Management: steroid therapy: p/o prednisolone 1mg/kg divided. eyecare: tape shut, gold implants in eyelids, patch, protective ointment & artificial tears etc. antiviral therapy for herpes infections.

Surgical management of facial paralysisMuscle transfer: masseter, temporalis.Nerve cable grafting: greater auricular[10cm,in the

region], sural nerve[more fascicles,longer graft 40cm] grafts.

Direct nerve repairCross facial graftingFacial hypoglossal anastomosisRemoval of other known etiology: tumours, trauma

management [temporal #] etc.Mastoidectomy or middle cranial fossa decompression.

Other conditions assosciated with facial nerve

Crocodile tears: gustolacrimal reflex. Patient with VII palsy who has affected secretomotor fibres [tearing & salivation], may have tearing at mealtime due to abberant fibre regeneration.

Spastic pareitic facial contracture: damage at nuclear/supranuclear level. [causes: intrinsic pontine disease- stroke/ neoplasm/ MS, cerebellopontine angle mass, bell’s palsy, Guillain barre synd.

Blepharospasm: bilateral episodic involuntary orbicularis oculi contractions.sometimes assosc with lower facial musculature spasm, orofacial dyskinesia etc.

etiol: essential, progressive supranuclear palsy, parkinsonism, MS, brainstem stroke.

management: clonazepam, botulinum toxin [chemodenervation], selective nerve sectioning, myectomies.

Hemifacial spasm: usually unlateral, involving half of facial

muscle, typially lasting several mins at a time, present during sleep.

etiol: post bell’s, abberant vascular loop compressing VII in subarachnoid space where it exits pons.

treatment: carbamazepine/clonazepam etc., chemodenervation, surgical.

Facial myokymia: myokymia is spontaneous,fine fascicular muscle contractions of muscle without muscular atrophy or weakness.usually benign, self limiting. If persistent, consider MS, brainstem glioma, stroke.

Jaw winking syndrome: a facial synkinesis, triggerd by jaw opening, causing closure of the eyelids on the side of facial palsy. [usually assosc with congenital facial palsy] .

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