Facial Nerve Paralysis

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Facial Nerve Paralysis

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Outlines

• Anatomy
• Classification
• Evaluation
• Electrodiagnosis testing
• Management
• Bells palsy ,Ramse Hunt syndrome
• Temporal bone fracture

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Anatomy of Facial nerve

• The facial nerve contains approximately 10,000
  fibers
• 7000 myelinated fibers innervate the muscles of
  facial expression, stapedius muscle,
  postauricular muscles, posterior belly of
  digastric muscle, and platysma
• 3000 fibers form the nervus intermedius (Nerve of
  Wrisberg)
• sensory fibers (taste) from the anterior 2/3 of
  the tongue
• taste fibers from soft palate via palatine and
  greater petrosal nerve
• parasympathetic secretomotor fibers to the
  parotid, submandibular, sublingual, and lacrimal
  gland

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Anatomy of Facial nerve

• 1) Intracranial part
• Supranuclear segment
• Nuclear segment
• Infranuclear segment
• Cerebellopontine angle
• Internal acoustic canal
• Labyrinthine segment
• Tympanic segment
• Mastoid segment
• 2) Extracranial part

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Supranuclear segment

• Cerebral cortex ? Corticobulbar tract ? Facial
  nucleus (pons)
• Upper face ? crossed uncrossed
• Lower face ? crossed only

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Nuclear segment

• Facial motor nucleus
• lower 1/3 of Pons
• abducent nucleus
• Out from brain stem at pons recess between olive
  and inferior cerebellar peduncle

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Nervous intermedius

• Parasympathetic secretory fibers arise from
  superior salivatory nucleus
• These preganglionic fibers travel to the
  submandibular ganglion via the chorda tympani
  nerve to innervate the submandibular and
  sublingual glands
• And to sphenopalatine ganglion via greater
  superficial petrosal nerve to innervate lacrimal,
  nasal, and palatine gland

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Nervous intermedius

• Secretory fibers of lesser superficial petrosal
  nerve tranverse tympanic plexus, synapse in otic
  ganglion, and travel via auriculotemporal nerve
  to innervate parotid gland
• Taste fibers from anterior 2/3 of tongue reach
  geniculate ganglion via chorda tympani nerve and
  from there travel to the nucleus of the tractus
  solitarius

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Infranuclear segment

• Cerebellopontine angle
• Internal acoustic canal
• Labyrinthine segment
• Tympanic segment
• Mastoid segment

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Cerebellopontine angle

• The facial nerve and nervus intermedius exit the
  brain stem at the pontomedullary junction and
  travel with CN VIII to enter the internal
  acoustic meatus

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Internal acoustic canal

• Motor facial nerve (medial)
• Nervus intermedius (between)
• Acoustic nerve (lateral)

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Labyrinthine segment

• Fallopian canal
• Shortest Narrowest part
• Temporal bone
• Facial nerve enter fallopian canal until middle
  ear
• First genu
• Geniculate ganglion
• Branches
• Greater superficial petrosal nerve ? lacrimal
  gland
• Lessor superficial petrosal nerve ? parotid gland

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Tympanic segment

• First genu ? above oval window ? stapes
• Second genu beyond middle ear
• Out of cranium through stylomastoid foramen

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Mastoid segment

• Stylomastoid foramen
• Branches
• Motor nerve to stapedius muscle
• Chorda tympani nerve between malleus and incus
• secretomotor Submandibular Sublingual gland
• taste fiber anterior 2/3 of tongue

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Extracranial segment

• Posterior auricular nerve auricularis,
  occipitalis and sensation at auricular, post
  auricular area
• Branch to posterior belly of digastric muscle and
  stylohyoid muscle
• Temporal branch muscle above zygoma
• Zygomatic branch orbicularis occli
• Buccal branch buccinator and upper lip
• Marginal mandibular branch orbicularis oris and
  lower lip
• Cervical branch platysma

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Physiology

• Efferent fibers from the motor nucleus
  innervate muscles of facial expression,
  post-auricular, stylohyoid, posterior digastric,
  and stapedius muscles
• Efferent fibers ANS (preganglionic
  parasympathetic fiber)
• sphenopalatine ganglion to lacrimal glands and
  mucinous glands of nose
• submandibular ganglion to submandibular and
  sublingual glands

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Physiology

• Afferent fibers convey taste from anterior
  two-thirds of tongue to nucleus tractus
  solitarius via lingual nerve, chorda tympani, and
  nervus intermedius.
• Afferent fibers mediate sensation from posterior
  external auditory canal, concha, ear lobe, and
  deep parts of face

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Classifications of facial nerve injury

• Seddon classification of nerve injury
• Neuropraxia
• Axonotmesis
• Neurotmesis

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Classifications

• Sunderland classification of nerve injury
• 1 damage Compression
• 2 damage Interruption of axoplasm
• 3 damage Disruption of myelin
• 4 damage Disruption of perineurium,
  myelin and axon
• 5 damage Transection of nerve

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Sunderland Classification of nerve injury
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Nerve injury

• neurapraxia Sunderland grade 1
• axonotmesis Sunderland grade 2-3
• neurotmesis Sunderland grade 4-5

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Degeneration

• Interruption of the continuity of the axon
  separates the distal axon from its metabolic
  source, the neuron or cell body
• Wallerian degeneration of the distal axon and
  myelin sheath begins within 24 hours
• Macrophages phagocytose degraded myelin and axons

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Regeneration

• Complete
• Partial
• Simple misdirection
• Clinical expression synkinesis or associated
  movement
• Complex misdirection
• Clinical expression mass movement

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Differential Diagnosis

1. Extracranial
2. Intratemporal
3. Intracranial

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Extracranial

• 1. Traumatic
• Facial lacerations
• Blunt forces
• Penetrating wounds
• Mandible fractures
• Iatrogenic injuries
• Newborn paralysis

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Extracranial

• 2. Neoplasm
• Parotid tumors
• Tumors of the external and middle ear
• Facial nerve neurinomas
• Metastatic lesions
• 3. Congenital absence of facial musculature

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Intratemporal

• 1. Traumatic
• Fractures of petrous pyramid
• Penetrating injuries
• Iatrogenic injuries
• 2. Neoplastic
• Cholesteatoma
• Facial neurinomas
• Hemangiomas
• Meningiomas
• Acoustic neurinomas

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Intratemporal

• 3. Infectious
• Herpes zoster oticus
• Acute otitis media
• Chronic otitis media
• Malignant otitis externa
• 4. Idiopathic
• Bell's palsy
• Melkersson-Rosenthal syndrome
• 5. Congenital osteopetroses

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Intracranial

• 1. Iatrogenic injury
• 2. Neoplastic
• 3. Congenital
• Mobius syndrome
• Absence of motor units

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History

• Onset
• Previous symptoms
• Complete or incomplete
• Unilateral or bilateral
• Pain
• Underlying disease (vestibulocochlear)
• Associate symptoms
• Alteration in taste or lacrimation

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History

• Family history
• Trauma
• Hx of viral infection
• Vaccination
• DM
• HTN
• Pregnancy

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Physical examination

• ENT exam
• Nervous system
• Location
• Severity

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Evaluation of Facial paralysis

• Clinical feature
• Central VS Peripheral facial paralysis
• Complete head and neck examination
• Cranial nerve evaluation
• Electrodiagnostic testing
• Topographic diagnosis

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Central facial paralysis

• Upper motor neurone lesion
• Movements of the frontal and upper orbicularis
  oculi tend to be spared
• Because of uncrossed contributions from
  ipsilateral supranuclear areas
• Involvement of tongue
• Involvement of lacrimation and salivation

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Peripheral paralysis

• Lower motor neurone lesion
• At rest
• less prominent wrinkles on forehead of affected
  side, eyebrow drop, flattened nasolabial fold,
  corner of mouth turned down
• Unable to
• wrinkle forehead, raise eyebrow, wrinkle
  nasolabial fold, purse lips, show teeth, or
  completely close eye

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House-Brackmann grading system

• Grade I - Normal
• Grade II - Mild dysfunction, slight weakness on
  close inspection, normal symmetry at rest
• Grade III - Moderate dysfunction, obvious but not
  disfiguring difference between sides, eye can be
  completely closed with effort
• Grade IV - Moderately severe, normal tone at
  rest, obvious weakness or asymmetry with
  movement, incomplete closure of eye
• Grade V - Severe dysfunction, only barely
  perceptible motion, asymmetry at rest
• Grade VI - No movement

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Topographic Diagnosis

• To determine the anatomical level of a peripheral
  lesion
• Lacrimation ? Geniculate ganglion
• Stapedius reflex ? motor nerve of stapedius
  muscle
• Taste ? chorda tympani

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Schirmer's Test

• Geniculate ganglion petrosal nerve function
  test
• Schirmers test ve when
• Affected side shows less than half the amount of
  lacrimation seen on the normal side
• Sum of the lengths of wetted filter paper for
  both eyes less than 25 mm
• Lesion at or proximal to the geniculate ganglion

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Stapedius reflex

• Nerve to stapedius muscle test
• Impedance audiometry can record the presence or
  absence of stapedius muscle contraction to sound
  stimuli 70 to 100 dB above hearing threshold
• An absence reflex or a reflex less than half the
  amplitude is due to a lesion proximal to
  stapedius nerve

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Taste (Electrogustometry)

• Chorda tympani nerve test
• Solution of salt, sugar, citrate, quinine or
  Electrical stimulation
• Compares amount of current require for a response
  each side of tongue
• Normal difference lt 20 uAmp (thresholds
  differening by more than 25 abnormal)
• Total lack of Chorda tympani No response at 300
  uAmp
• Disadvantage False ve in acute phase of Bells
  palsy

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Minimal stimulation test

• ???????????????????????????? ? ?????
  ???????????????? ????????????????????????????????
  ????????
• ????????????????????????????
• neurapraxia ??????????????????????????????????????
  ????????????
• axonotmesis ??????????????????????????????????????
  ??????????????????????????????????????????????????
  ??
• neurotmesis ????????????????????????????????
  

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Minimal stimulation test

• ????????????????????????????????????
• ???????? ? ???????????????????????????????????????
  ??????????????????????????????????????
• ???????????????????
• ?????????????????????????????????????????????????
  
• ???????????????????? 3.5 mA ? Wallerian
  degeneration

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Maximal stimulation test (MST)

• ??????????????????????????????????? neurapraxia
  ??????? axon ?????????????????????????????????????
  ??????????????????????
• ??????????????????????????? axonotmesis ???????
  axon ?????????????????????????????????????????????
  ?????????????????????????????????
• ???????????????????? neurotmesis
  ??????????????????????????????????????????????????
  ????????????????????

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Maximal stimulation test (MST)

• ????????????????? 5 mA ?????????????????????????
  ???????
• ??????????????? ????????? ???? 2
  ??????????????????
• ?????????????????? facial nerve
  ????????????????????????????? ?????? 12
• ????????????????? ????????????????????????????
  ?????? 73
• ?????????????????? facial nerve
  ????????????????????? ?? misdirection ????

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Electroneurography (ENOG )

• ???????????????????? MST
• ????????????????????? ??????????????????
  summating potential
• ??????????????????????????? amplitude
  ????????????????????????????????????
• ??? amplitude ??? SP ????????????????????????????
  ???????????? 5-10 ??????????????????????????
  90-95 ?????????????????? facial nerve
  ?????????????????? ????? misdirection???

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Electromyography (EMG)

• ??????????????????????????????????????????????????
  ??
• ???????????????????? facial palsy ?????????????
  10 ???
• ???????????????? Wallerian degeneration
  ??????????????????????????????????????????????????
  ????????????????????????
• ????????? fibrillatioin ??????? facial nerve
  ?????????????????????
• ????????? motor unit potential
  ??????????????????????????????????????????????????
  ???????????

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Limitation of Electrodiagnostic testing

1. ??????????????????????????????????????????????????
   ??? 72 ???????
2. ??????? EMG ?????????????????????????????????????
   ??? 10 ???
3. ??????????????????????????????
   ?????????????????????????????? (?????? EMG)

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Management

• Extracranial etiology
• Trauma
• Iatrogenic
• Neoplasm

• Intratemporal etiology
• Fracture
• Iatrogenic
• Neoplasm
• Idiopathic (Bells palsy)
• Infection

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Idiopathic facial palsy (Bell's Palsy)

• Most common cause of facial paralysis (gt50 of
  case)
• Most age 25-30 yrs.
• Male Female 1 1
• Left side Right side 1 1
• Unilateral gt bilateral
• Increase risk in
• pregnancy 3.3 times
• DM 4.5 times
• Recurrent rate 10
• 60 have previous URI

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Etiology

• Unknown
• Microcirculatory failure of vasa nervorum
• Viral infection (HSV)
• Ischemic neuropathy
• Autoimmune reaction
• Entrapment theory

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Diagnosis

• By exclusion
• Criteria
• Paralysis or paresis of all muscle groups of one
  side of the face
• Sudden onset
• Absence of signs of CNS disease
• Absence of signs of ear or CPA disease

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Medical treatment

• Corticosteroids
• prednisolone 1 mg/kg/day 7-10 days
• Corticosteroids combine with antiviral drug is
  better
• Acyclovir 400 mg 5 times/day
• Famciclovir and valacyclovir 500 mg bid

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Surgical treatment

• Facial nerve decompression
• Indication
• Completely paralysis
• ENOG less than 10 in 2 weeks
• Appropriate time for surgery is 2-3 weeks after
  paralysis

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Herpes Zoster Oticus (Ramsay Hunt Syndrome)

• 3rd most common of peripheral facial paralysis
  (10)
• Aged gt 60 yrs. or low immune (low CMIR)
• Virus travels to the dorsal root extramedullary
  cranial nerve ganglion
• Infected of HZV at auricular, external canal or
  face
• Prodromal symptoms very similar to those seen in
  Bell's palsy
• but usually more severe

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Herpes Zoster Oticus (Ramsay Hunt Syndrome)

• Symptoms include severe otalgia, facial
  paralysis, facial numbness, and a vesicular
  eruption on the concha, external auditory canal,
  and palate
• Facial paralysis hearing loss vertigo ?
  canal paralysis
• Pathophysiology treatment liked in Bell s
  palsy

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Temporal bone fractures

• Longitudinal fracture
• Transverse fracture
• Mixed fracture

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Temporal bone fractures

• Signs
• bleeding from the external canal
• hemotympanum
• step-deformity of the osseous canal
• conductive hearing loss (longitudinal fracture)
• sensorineural hearing loss (transverse fracture)
• CSF otorrhea
• facial nerve involvement (20 of longitudinal
  fractures and 50 of transverse fractures)

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Longitudinal VS Transverse
Type of injury Longitudinal Transverse
Incidence 70-90 10-20
Site of injury Temporal , Parietal area Occipital , Frontal area
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Origin of fracture site Temporal squama Foramen magnum
Direction of injury Posterosuperior of EAC cross roof of middle ear along carotid canal anterior to labyrinthine capsule Between various foramen Jugular F. Hypoglosal F. Labyrinthine capsule
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Insertion middle cranial fossa middle cranial fossa
Tympanic mb. Middle ear Inner ear ??????????? ?????????????????? ???????????????? ????, hemotympanum ????????? ??????????????????
Hearing loss Vertigo CHL No SNHL Common
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Facial paralysis Onset 20-25 Delayed, transient 50 Immediate, permanent
Site of lesion Tympanic segment , Perigeniculate ganglion Labyrinthine segment
CSF otorrhea No Common
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Cardinal SS 1.Bleeding from ear 2.CHL 3.Battles sign 1.VertigoNystagmus 2.SNHL 3.Facial paralysis 4.Hemotympanum
CT-scan Axial sagital section Coronal 20degree coronal oblique section
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Prognosis

• Immediate onset paralysis poor prognosis
• Delayed onset paralysis good prognosis
• All case of paralysis ? electrical testing

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Treatment

• Surgery is treatment of choice
• Indications for facial nerve exploration
• incomplete paralysis
• iatrogenic paralysis
• Contraindications any case have no poor
  prognostic factors

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Complications

• Complications of facial nerve decompression
• dural tears
• conductive or sensorineural hearing loss
• vestibular function loss
• persistent CSF leaks
• meningitis
• injury to the anterior inferior cerebellar artery
  (AICA) or its branches