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facial nerve by Dr. Roop

  1. 1. Facial nerve Unit head –Dr. Prabhat Kanvriya Presented by-Dr. Roopsingh Department of medicine SNMCjodhpur
  2. 2. Outline- • Introduction • Anatomy • Clinical examination –Examination of motor system -Examination of Reflex -Examination of sensory system -Examination of secretory function • Disordes-facial weakness • Localization of facial nerve palsy
  3. 3. Introduction- • Mixed nerve with motor and sensory roots. • Facial nerve is seventh cranial nerve • Emerges from the brain stem between the pons and medulla, controls muscles of facial expression, and muscles of the scalp and ear, as well as buccinator, platysma, stapedius, stylohyoid, and posterior belly of the digastric. • Functions in conveyance of taste sensations from the anterior two thirds of the tongue and oral cavity
  4. 4. Cont.. • Carries parasympathetic secretory fibers to submandibular and sublingual salivary glands, lacrimal gland and to mucous membranes of oral and nasal cavities. • Conveys exteroceptive sensation from eardrum and external auditory canal, proprioceptive sensation from muscles it supplies, and general visceral sensation from salivary glands and mucosa of the nose and pharynx.
  5. 5. ANATOMY-Facial nerve has mainly two parts- 1. Facial nerve proper(Motor) 2. Nervus intermedius
  6. 6. {1} Facial nerve proper (motor): Arising from facial motor nucleus in pons. Supranuclear innervation to the muscles of facial expression arises from the lower third of contralateral precentral gyrus in facial area of motor homunculus. Portion of nucleus that innervates the lower half to two thirds of the face has predominantly contralateral supranuclear control; Portion that innervates upper third to half has bilateral control.
  7. 7. Facial nucleus is special visceral efferent, or branchiomotor; It innervates the muscles of the second branchial arch Facial motor nucleus has lateral, medial, and dorsal subnuclei, arranged in columns. Exits the pons laterally at the pontomedullary junction, just caudal to the roots of CN V between the olive and the inferior cerebellar peduncle Has two components, motor root, which makes up about 70% of the fibers, and sensory root, which accounts for 30%.
  8. 8. facial nerve in pons
  9. 9. 2 .Nervus intermedius: • Sensory and autonomic component of the facial nerve. • Runs in a position intermediatebetween CNs VII and VIII across the CPA • At first external genu, NI fuses with the geniculate ganglion. • Sensory cells located in the geniculate ganglion are general somatic afferent (GSA) and special visceral afferent (SVA)
  10. 10. Course and relations: 1. • Intracranial (intrapetrosal) course 2. • Extracranial course
  11. 11. (1)Within the facial canal- 1- Greater superficial petrosal nerve (GSPN) : • carries preganglionicparasympatheticfibers • These fibers are conveyed by the NI to geniculateganglion. • Pass through the ganglionwithoutsynapsing into the greater petrosal nerve, which goes forward through the hiatusof the facialcanal to join deep petrosalnerve from the carotid sympatheticplexus to form the vidian nerve, or the nerve of the pterygoid canal, which runs to the sphenopalatineganglion,from where postganglionicfibers proceed to the lacrimalgland. 2-Nerve to stapedius: supplies the stapedius muscle
  12. 12. Conte…. •3- Chorda tympani nerve: • • It arises from the facial nerve 6 mm above the stylomastoid foramen and runs upwards to perforate the posterior bony wall of the tympanic cavity • . • It carries taste and general visceral afferent (GVA) fibers as well as preganglionic parasympathetics.
  13. 13. (II)- At exit from the stylomastoid foramen • 1- Posterior auricular nerve: Supplies the occipitalis , posterior auricular, and transverse and oblique auricular muscles. • 2- Digastric branch: Posterior belly of digastric muscle • 3-Stylohyoid branch: Stylohyoid muscle
  14. 14. (III) IN FACE • A. Temporal • B Zygomatic • C Buccal • D Marginal mandibular • E Cervical
  15. 15. GANGLIA ASSOCIATED WITH FACIALNERVE- • Geniculate ganglion • Submandibular ganglion • Pterygopalatine ganglion
  16. 16. SubmandibularGanglion -The submandibular ganglion is small and fusiform in shape -It is situated above the deep portion of the submandibular gland, on the hyoglossus muscle, near the posterior border of the mylohyoid muscle. - The ganglion 'hangs' by two nerve filaments from the lower border of the lingual nerve (itself a branch of the mandibular nerve, CN V3). It is suspended from the lingual nerve by two filaments, one anterior and one posterior. Through the posterior of these it receives a branch from the chorda tympani nerve which runs in the sheath of the lingual nerve.
  17. 17. PterygopalatineGanglion- • The pterygopalatine ganglion (meckel's ganglion, nasal ganglion or sphenopalatine ganglion) is a parasympathetic ganglion found in the pterygopalatine fossa. • It's largely innervated by the greater petrosal nerve (a branch of the facial nerve); and its axons project to the lacrimal glands and nasal mucosa
  18. 18. CLINICAL EXAMINATION - Inspection- - Facial asymmetry, nasolabial fold with forehead wrinkles, movements during spontaneous facial expression • Tone of the muscles of facial expression, • Atrophy and fasciculations • Abnormal muscle contractions and involuntary movements• Spontaneous blinking for frequency and symmetry.
  19. 19. (A) Testing of Facial nerve(motor system) Testing the temporal branches of the facial nerve – patient is asked to frown and wrinkle his or her forehead. Testing the Zygomatic branches of the facial nerve- patient is asked to close their eyes tightly Testing the buccal branches of the facial nerve • Puff up cheeks (buccinator) • Smile and show teeth (orbicularis oris) • Tap with finger over each cheek to detect ease of air expulsion on the affected side
  20. 20. (B)Examination of Reflexes • Corneal Reflex • Afferent limb of the reflex is mediated by CN V1, the efferent limb by CN VII.
  21. 21. Stapedius reflex- • Nerve to stapedius muscle test • Impedence audiometry can record the presence or absence of stapedius muscle contraction to sound stimuli 70 to 100 db above hearing threshold • Absence reflex or a reflex less than half the amplitude is due to a lesion proximal to stapedius nerve.
  22. 22. (c)Examination of Sensory Functions- -Hypesthesia of posterior wall of the external auditory meatus in proximal facial nerve lesions. -Taste on anterior two-thirds of the tongue-use four substances for testing: • Sucrose (sweet), sodium chloride (salty), quinine (bitter), and citric acid (sour). • Patient with a peripheral pattern of facial weakness has impaired taste, the lesion is proximal to the junction with the chorda tympani.
  23. 23. (D)Examinationof secretoryfunction- • Examination ofSecretory Functions • Tear productionmay be quantitated with the Schirmer test. • Lacrimalreflex istearing, usually bilateral, caused by stimulatingthe cornea. • Nasolacrimalreflex iselicited by mechanicalstimulation ofthe nasal mucosa, or by chemicalstimulation usingirritatingsubstancessuch as ammonia. • Abnormalitiesofsalivation are usually suggested by the history.
  24. 24. • • TOPOGNOSTIC TESTING- tear-hear-taste-face • 1. Schirmer test for lacrimation (GSPN) • 2. Stapedial reflex test (Stapedial branch) 3. • 3.Taste testing (Chorda tympani nerve) • 4. Salivary flow rates & pH (Chorda tympani) • • ELECTROPHYSIOLOGIC TESTS • 1. Nerve stimulation test (NST) • 2. Electromyography(EMG) • 3. Maximal stimulation test (MST)
  25. 25. Facial weakness- • Two types of neurogenic facial nerve weakness: • Peripheralor lower motor neuron - result from a lesion anywhere from the CN VII nucleus in the pons to the terminal branches in the face. • Central facial palsy (CFP)orupper motor neuron - due to a lesion involving the supranuclear pathways before they synapse on the facial nucleus.
  26. 26. Peripheral Facial Palsy- • There is flaccid weakness of all the muscles of facial expression on the involved side, both upper and lower face, and the paralysis is usually complete
  27. 27. Cont.. • Palpebral fissure is open wider than normal, and there may be inability to close the eye (lagophthalmos). • Very mild PFP may produce only slower and less complete blink on the involved side. • Bell’s phenomenon- Attempting to close involved eye causes a reflex upturning of the eyeball • Levator sign of Dutemps and Céstan- Patient look down, then close the eyes slowly; because the function of levator palpebrae superioris is no longer counteracted by orbicularis oculi, upper lid on the paralyzed side moves upward slightly.
  28. 28. • Negro’s sign- eyeball on the paralyzed side deviates outward and elevates more than the normal one when the patient raises her eyes. • Bergara-Wartenberg sign- loss of the fine vibrations palpable with the thumbs or fingertips resting lightly on the lids as the patient tries to close the eyes as tightly as possible. • Platysma sign of Babinski- asymmetric contraction of the platysma, less on the involved side, when the mouth is opened
  29. 29. 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
  30. 30. Bell’s Palsy • Most common form of lower motor neuron facial palsy. • Incidence is 23/1,00,000 • 1 in 6o life time occurrence of single episode • Affects men and women equally , all ages ,all times of the year. • Increased occurrence in the elderly diabetics, hypertensives than in the common people. • Increased incidence in women during the third trimester of pregnancy 2 weeks preceding delivery ,first two weeks postpartum.
  31. 31. Etiology: • Idiopathic • Herpes simplex virus 1 • Herpes zoster is probably second most common viral infection associated with PFP. • Other viruses implicated include cytomegalovirus, Epstein-Barr virus, human herpes virus 6, and coxsackie. • Inactivated intra nasal influenza vaccine
  32. 32. Clinical features- • Onset of bell’s palsy is acute. • ½ of the cases attainmaximumparalysisin 48 hours. • All cases are clinicallyprominent by 5 days. • Pain behind the ear may precede the paralysis by a day or two . • Impairement of taste is present to some degree in all cases– rarely beyond second week of paralysis. • Hyperacusis or distortionof sound in ipsilateralear ---paralysis of stapedius muscle. • Paralysis is partialin 30%,complete in 70%cases. • About 1% of cases are bilateral
  33. 33. • Enhancement of the facial nerve on gadolinium enhanced MRI . Increased lymphocytes ,mononuclear cells in CSF. Prognosis • 80% patients recover within a few weeks.2-12 weeks • 10%--permanent long term sequelae .• 8%--recurrence
  34. 34. Treatment- • Symptomatic • Protection of eye during the sleep patch • Massage of the weakened muscles • Lubricating eye drops • Prednisolone60-80 mg/day in divided doses intial4-5 days,thentaper over next 7-10 days. • Acyclovir alone is not useful. • Acyclovir 400mg 5 times a day –10 days • Valacyclovir 1000mg /day 5-7 days. • No evidence that surgicaldecompressionof facial nerve is effective --- may be harmful.
  35. 35. Facial Weaknessof Central Origin • Weakness of the lower face, with relative sparing of upper face • Upper face is not necessarily completely spared, but it is always involved to a lesser degree than the lower face. • Lesion involving the corticobulbar fibers anywhere prior to their synapse on the facial nerve nucleus will cause a CFP • Lesions are most often in the cortex or internal capsule.
  36. 36. • • There are two variations of CFP: • (a) Volitional, or voluntary- weakness more marked on voluntary contraction, when patient is asked to smile or bare her teeth. • Result from a lesion involving either the cortical center in the lower third of the pre-central gyrus that controls facial movements, or the corticobulbar tract. (b) Emotional, or mimetic –Facial asymmetry more apparent with spontaneous expression, as when laughing. • Most commonly results from thalamic or striatocapsular lesions, usually infarction, rarely with brainstem lesions
  37. 37. Difference bw UMN &LMN Facial palsy-
  38. 38. Syndromes associated with facial nerve. • Crocodile tear syndrome - involves lacrimation or tearing whenever the patient is eating or drinking. Freys syndrome- complication of surgery or an injury of the salivary (parotid) gland in the cheek. • Symptoms include sweating and flushing on the cheek, temple or near the ear, particularly when eating foods
  39. 39. Ramsay Hunt syndrome- • A special form of Herpes zoster infection of the Geniculate ganglion with the involvment of the external ear and the oral mucosa. Triad- 1.Ipsilatral facial paralysis 2.Ear pain 3.vesciles in ear canal and auricle
  40. 40. Melkersson Rosenthal syndrome • Recurrent attacks of facial paralysis • Associated with multiple episodes of non- pitting, non-inflammatory painless edema of the face • Chelitis granulomatosa • Fissured tongue
  41. 41. MOBIUS SYNDROME • Möbius’ syndrome (congenital oculofacial paralysis) is the association of congenital facial nerve palsy with paralysis of the extraocular muscles, especially the lateral rectus due to hypoplasia or aplasia of the CN nuclei .
  42. 42. • Millard-Gubler syndrome – • ipsilateral facial peralysis • contralateral hemiparesis • Foville syndrome • ipsilateral facial peralysis and • horizontal gaze palsy with • contralateral hemiparesis
  43. 43. •THANK YOU
  44. 44. • REFERENCES • DeJong’s The Neurological examination, 7th edition • Grays Anatomy : 39th Edition • UptoDate. Com