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1、Facial Nerve Palsy,Anatomy,Facial nerve is a mixed nerve,having a motor root and a sensory rootMotor root supplies all the mimetic muscles of the face which develop from the 2nd brachial arch,Sensory root“nerve of Wrisberg”carries taste fibers from the anterior 2/3 of the tongue and general sensatio
2、n from the concha and retroauricular skinAlso it carries secretomotor fibers to the lacrimal,submandibular and sublingual glands as well as those in the nose and palate,Anatomy,Anatomy:Parts,Intracranial partIntratemporal partExtracranial part,Course of the Facial Nerve,Intracranial Arises at the po
3、ntomedullary junction and courses with CNVIII to the internal acoustic meatus12mm,Intratemporal Meatal Labyrinthe segmentTympanic segmentMastoid segment,Course of the Facial Nerve,Extracranial From stylomastoid foramen to pesanserinus,Course of the Facial Nerve,Anatomy:Branches,Greater superficial p
4、etrosal nerveNerve to stapediusChorda tympaniComunicating branchPosterior auricular nerveMuscular branchesPeripheral branches:“Pes anserinus”,Presentation,Functional and cosmetic problemsUpper lid fails to drop down and closeLower lid loses tone and sags downwardMay evert leading to ectropionProduce
5、s lagophthalmos and consequent corneal exposure.,Presentation,Interruption of the tear filmLeads to drying of corneaOcular discomfortCorneal ulcersInfectionPerforation,Upper motor neurone(UMN)can wrinkle their forehead(unless bilateral lesion)Lower motor neurone(LMN)cant wrinkle their forehead,Prese
6、ntation,House-Brackmann Facial NerveGrading Scale,I.Normal II.Mild dysfunction(slight weakness noticeable on close inspection)III.Moderate dysfunction(obvious weakness,but not distinguishing differences between the two sides of the face)IV.Moderately severe dysfunction(obvious weakness and disfigure
7、ment)V.Only barely perceptive motor function VI.Complete paralysis,Diagnosis,HistoryPresentationHearing testVestibular functionMRI/CTTopognostic-Where is the lesion?Qualitative-Degree of the lesion,Schirmers tear testStapedius reflexTaste testSubmandibular salivary flow test,Topodiagnostic Diagnosis
8、,Topodiagnostic Diagnosis,Qualitative Diagnosis,Nerve Excitability Test:NETMaximum stimulation Test:MSTElectroneurography:ENoGElectromyography:EMG,Bells Palsy,60-70%casesPathophysiology Impaired“axoplasmic”flow from edema of facial nerve within fallopian canalRapid onset and evolution 48 hoursMay be
9、 associated with acute neuropathies of cranial nerves V-XPain or numbness affecting ear,mid-face,tongue and taste disturbancesRecurrences are more likely(2.5x)in patients with family history,immunodeficiency or diabetes,Pathophysiology,Main cause of Bells palsy is latent herpes viruses(herpes simple
10、x 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.,Oral antivirals-Acyclovir CorticosteroidEye protection-lacrilubeFollow progression with serial examsF
11、acial nerve decompressionProgression to 90%degeneration on ENOGPerformed before irreversible injury to the endoneurial tubules occurs(two weeks),will allow for axonal regeneration to occur,Treatment,Herpes Zoster Oticus(Ramsay Hunt syndrome),Herpes Zoster Oticus(Ramsay Hunt syndrome),10-15%of acute
12、facial palsy casesLesions may involve the external ear,the skin of EAC or soft palateAssociated symptoms hearing loss,dysacusis and vertigoAdditional involvement of CN V,IX and X and cervical branches 2,3 and 4Pathogenesis Neural injury due to edema at point between the meatal foramen and the geniculate fossa in the labyrinthe segment,Thanks！,
