上海市第六人民医院Shanghai Sixth People’s Hospital

Shankai Yin Prof Dept of Otolaryngology, the sixth hospital affilia

ted to Shanghai jiaotong university Otolaryngology institute at Shanghai jiaotong u

niversity

Facial Nerve Disease

上海市第六人民医院Shanghai Sixth People’s Hospital

Anatomy

Facial nerve is a mixed nerve, having a motor root and a sensory root.

Motor root supplies all the mimetic muscles of the face which develop from the 2nd brachial arch.

上海市第六人民医院Shanghai Sixth People’s Hospital

Sensory root “nerve of Wrisberg” carries taste fibers from the anterior 2/3 of the tongue and general sensation from the concha and retroauricular skin.

Also it carries secretomotor fibers to the lacrimal, submandibular and sublingual glands as well as those in the nose and palate.

上海市第六人民医院Shanghai Sixth People’s Hospital

Anatomy: Parts

Intracranial part

Intratemporal part

Extracranial part

上海市第六人民医院Shanghai Sixth People’s Hospital

Course of the Facial Nerve

Intracranial Arises at the pontomedullary junction and c

ourses with CNVIII to the internal acoustic meatus

12mm

上海市第六人民医院Shanghai Sixth People’s Hospital

Intratemporal Meatal

Anterior to the superior vestibular nerve and superior to the cochlear nerve – 10mm

Labyrinthe segment Passes through narrowest part of fallopian canal - 12mm Narrowest part of facial nerve. The most susceptible to compres

sion secondary to edema. Tympanic segment

From geniculate ganglion to pyramidal turn – 11mm Mastoid segment

Exits the stylomastoid foramen – 13mm

上海市第六人民医院Shanghai Sixth People’s Hospital

Extracranial From stylomastoid foramen to pesanserinus

上海市第六人民医院Shanghai Sixth People’s Hospital

Anatomy: Branches

Greater superficial petrosal nerve Nerve to stapedius Chorda tympani Comunicating branch Posterior auricular nerve Muscular branches Peripheral branches: “Pes anserinus”

上海市第六人民医院Shanghai Sixth People’s Hospital

3-D t bone

上海市第六人民医院Shanghai Sixth People’s Hospital

Presentation

Functional and cosmetic problems Upper lid fails to drop down and close Lower lid loses tone and sags downward

May evert leading to ectropion Produces lagophthalmos and consequent

corneal exposure. Interruption of the tear film Leads to drying of cornea

Ocular discomfort Corneal ulcers Infection Perforation

上海市第六人民医院Shanghai Sixth People’s Hospital

Upper motor neurone (UMN) can wrinkle their forehead (unless bilateral les

ion) sagging of the face seen with lower motor neu

rone palsies is not as prominent. Lower motor neurone (LMN)

can't wrinkle their forehead

上海市第六人民医院Shanghai Sixth People’s Hospital

上海市第六人民医院Shanghai Sixth People’s Hospital

House-Brackmann Facial NerveGrading Scale

I NormalII Normal tone and symmetry at rest. Slight weakness on close inspection

Good to moderate movement of forehead. Complete eye closure with minimum effort. Slight asymmetry of mouth with movement

III Normal tone and symmetry at rest. Obvious but not disfiguring facial asymmetry. Synkinesis may be noticeable but not severe .+/- hemifacial spasm or contracture. Slight to moderate movement of foreheadComplete eye closure with effort. Slight weakness of mouth with maximum effort.

IV Normal tone and symmetry at rest. Asymmetry is disfiguring or results in obvious facial weakness. No perceptible forehead movement. Incomplete eye closure. Asymmetrical motion of mouth with maximum effort

V Asymmetrical facial appearance at rest. Slight, barely noticeable movement. No forehead movement. Incomplete eye closure. Asymmetrical motion of mouth with maximum effort.

上海市第六人民医院Shanghai Sixth People’s Hospital

Degree of Lesion

Sunderland classification 1° Partial block: Neuropraxia 2° Loss of axons: axonotemesis 3° Injury to the endoneurium: neurotemesis 4° Injury to the perineurium: partial transection 5°Injury to the epineurium: complete

transection

上海市第六人民医院Shanghai Sixth People’s Hospital

上海市第六人民医院Shanghai Sixth People’s Hospital

Diagnosis

History Presentation Hearing test Vestibular function MRI / CT Topognostic - Where is the lesion? Qualitative -Degree of the lesion

上海市第六人民医院Shanghai Sixth People’s Hospital

Schirmer’s tear test Stapedius reflex Taste test Submandibular salivary flow test

Topodiagnostic Diagnosis

上海市第六人民医院Shanghai Sixth People’s Hospital

上海市第六人民医院Shanghai Sixth People’s Hospital

Qualitative Diagnosis

Nerve Excitability Test: NET Maximum stimulation Test: MST Electroneurography: ENoG Electromyography: EMG

上海市第六人民医院Shanghai Sixth People’s Hospital

Bell’s Palsy

60-70% cases Pathophysiology – Impaired “axoplasmic” flow from ede

ma of facial nerve within fallopian canal Rapid onset and evolution < 48 hours May be associated with acute neuropathies of cranial nerv

es V- X Pain or numbness affecting ear, mid-face, tongue and tast

e disturbances Recurrences are more likely (2.5x) in patients with family h

istory, immunodeficiency or diabetes

上海市第六人民医院Shanghai Sixth People’s Hospital

Pathophysiology

Main cause of Bell's palsy is latent herpes viruses (herpes simplex virus type 1 and herpes zoster virus), which are reactivated from cranial nerve ganglia.

Polymerase chain reaction techniques have isolated herpes virus DNA from the facial nerve during acute palsy.

上海市第六人民医院Shanghai Sixth People’s Hospital

Oral antivirals - Acyclovir - 10mg/kg (500mg) q8hrs x 7 days

Corticosteroid taper 1mg / kg / day for 10 days Eye protection - lacrilube Follow progression with serial exams Facial nerve decompression

Progression to > 90% degeneration on ENOG Performed before irreversible injury to the endoneurial

tubules occurs (two weeks), will allow for axonal regeneration to occur

Treatment

上海市第六人民医院Shanghai Sixth People’s Hospital

Herpes Zoster Oticus(Ramsay Hunt syndrome)

10-15% of acute facial palsy cases Lesions may involve the external ear, the skin of E

AC or soft palate Associated symptoms – hearing loss, dysacusis an

d vertigo Additional involvement of CN V, IX and X and cervi

cal branches 2, 3 and 4 Pathogenesis – Neural injury due to edema at poi

nt between the meatal foramen and the geniculate fossa in the labyrinthe segment

上海市第六人民医院Shanghai Sixth People’s Hospital

上海市第六人民医院Shanghai Sixth People’s Hospital

Thanks ！