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Facial Nerve Disease Shankai Yin Prof Dept of Otolaryngology, the sixth hospital affiliated to Shanghai jiaotong university Otolaryngology institute at Shanghai jiaotong university 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 courses 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 compression 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 上海市第六人民医院 Shanghai Sixth People’s Hospital 3-D t bone 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 lesion) sagging of the face seen with lower motor neurone 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 Nerve Grading Scale I II Normal 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 forehead Complete 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 Topodiagnostic Diagnosis Schirmer’s tear test Stapedius reflex Taste test Submandibular salivary flow test 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 edema of facial nerve within fallopian canal Rapid onset and evolution < 48 hours May be associated with acute neuropathies of cranial nerves V- X Pain or numbness affecting ear, mid-face, tongue and taste disturbances Recurrences are more likely (2.5x) in patients with family history, 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 Treatment 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 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 EAC or soft palate Associated symptoms – hearing loss, dysacusis and vertigo Additional involvement of CN V, IX and X and cervical branches 2, 3 and 4 Pathogenesis – Neural injury due to edema at point 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! 上海市第六人民医院 Shanghai Sixth People’s Hospital