facial nerve paralysis.pptx
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This document provides an overview of the facial nerve (cranial nerve VII), including its anatomy, branches, course, variations, testing, and causes of paralysis. Some key points: - The facial nerve has intracranial, intratemporal, and extratemporal segments as it passes through the skull and exits at the stylomastoid foramen. - It gives off numerous branches including the chorda tympani, nerve to stapedius, and branches in the parotid plexus. - Testing includes topognostic tests like lacrimation and salivary flow, as well as electrodiagnostic tools like EMG, NCT, and MST to evaluate
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facial nerve paralysis.pptx
- 2. INTRODUCTION Nerve of second branchial arch. Mixed nerve Course: Intracranial Intratemporal Extratemporal
- 3. Supranuclear pathway precentral gyrus of cerebral cortex – genu of internal capsule- pons – majority of fibers cross to reach opp side nucleus- some fibers terminate in ipsilateral nucleus. Emerge from lower border of pons – motor & sensory root ( nerve of Wrisberg)
- 5. Infranuclear pathway Leaves nucleus with 8th nerve in cerebellopontine angle- enter IAC Motor root: Muscles of facial expression Scalp Auricle Stylohyoid Stapedius Post belly of digastric
- 7. Sensory root: Special visceral afferent : taste to ant 2/3rd of tongue via chorda tympani General visceral efferent: salivary glands via petrosal Special visceral efferent: to facial muscles
- 8. Enter IAC- 7th nerve joins nervus intermedius – form common trunk- leaves IAC- enters fallopian canal in temporal bone. Total length in temporal bone- 22-33 mm.
- 10. Subdivided segments: Horizontal segment from fundus of internal acoustic meatus to geniculate gang.- 3- 4mm “ LABYRINTHINE SEGMENT” Acute angle turn to enter tympanic cavity- “FIRST GENU” Post on medial wall of middle ear above promontory- “ TYMPANIC SEGMENT” ( 10-12mm)
- 11. Curves down at pyramid and oval window at angle- “ SECOND GENU” “MASTOID/ VERTICAL SEGMENT”- from second genu to stylomastoid foramen ( 9-16mm). `
- 12. Facial ( fallopian ) canal ( Gerrier 1977): Individual sheath of pia mater curves up and continues with arachnoid. Slight constriction of nerve seen just prior to it labyrinthine segment 0.68 ( Fisch U, 1981) in diameter. Change in direction of the nerve that produces an angle of 132 deg, open anteriorly and medially.
- 14. Branches of facial nerve Intracranial: Greater superficial petrosal nerve ( secretomotor- lacrimal gland) Intratemporal: Nerve to stapedius- from mastoid segment ( supplies stapedius) Chorda tympani nerve- from mastoid segment- joins lingual nerve to supple ant 2/3rd of tongue, secretomotor to submand. Gland. Sensory branches join auricular branch of vagus to supply external auditory canal.
- 15. Branches in head & neck Ansa Haller ( inconstant)- immediately below stylomastoid foramen, anastomses with glossopharyngeal nerve. Posterior auricular nerve- 1-2mm below stylomastoid foramen. Styloid branch- enters styloid muscle. Branch to post belly of digastric.
- 16. Branches in parotid plexus Temporal branch Zygomatic branch Buccal Marginal mandibular Cervical
- 18. Landmarks of facial nerve Tragal pointer: 1 cm inf to tragal cartilage Tympanomastoid suture: angle where the vaginal process of tympanic portion of temporal bone meets mastoid process. Styloid process: lateral to styloid process.
- 19. Tracing terminal branch backwards: Ramus frontalis: tragus to lateral canthus Ramus buccalis: tragus to alar nose, parallel to zygoma. Ramus mandibularis: angle of mand. at pont 4- 4.5cm from attachment of lobule of pinna. Tendon of post belly of digastric Post auricular vein/ retromandibular vein
- 20. • Distance of FN from anatomical structures • Tragal pointer, 24.3 to 49.2 (mean 34) • Posterior belly of digastric, 9.7 to 24.3 (mean 14.6) • External auditory canal, 7.3 to 21.9 (mean 13.4) • Tympanomastoid suture, 4.9 to 18.6 (mean 10.0) • Styloid process, 4.3 to 18.6 (mean 9.8) • Transverse process of the axis, 9.7 to 36.8 (mean 16.9) • Angle of the mandible, 25.3 to 48.69 (mean 38.1). • The length of the facial nerve trunk from its point of exit from the stylomastoid foramen to its bifurcation into upper and lower divisions ranged from (mm) 8.6 to 22.8 (mean 14.0). Surg Radiol Anat. 2006 May;28(2):170-5. Epub 2006 Apr 20. Landmarks of the facial nerve: implications for parotidectomy. Pather N, Osman M.
- 21. Variations in course DINGMAN & GRABB,1962 Type I-no anastomosis occurred between branches of the facial nerve. Type II presence of an anastomotic connection between branches of temporofacial division. Type III-a single anastomosis between the temporofacial and cervicofacial divisions
- 22. Type IV a combination of type II and type III Type V two anastomotic rami passed from the cervicofacial division to interwine with the branches of temporofacial division. Type VI plexiform arrangement, the mandibular branch sent twig to join any members of the temporofacial division.
- 24. Neurophysiology & nerve regeneration Facial expression depends on 7000 motor fibres- muscle contractions. Degree of nerve injury: Neuropraxia Axontemesis Neurontemesis
- 25. Seddon classification Seddon, 1978 1st degree: compression, reversible, recovery complete. 2nd degree: interruption of axoplasm & myelin, persistent compression, recovery 1-2 months 3rd degree: increased intraneural pressure, loss of myelin tubes, recovery 2-4 months, incomplete recovery
- 27. 4th degree: partial transection, recovery- poor 5th degree: complete transection, no recovery Bells palsy & herpes zoster- 1-3 deg Trauma, tumour or cholesteatoma- 4th- 5th deg
- 28. Nerve regeneration Def: “ complex interactions of neurons, schwann cells, extracellular matrix & neurotrophic substances. Regeneration follows degeneration Sprouting at axonal end
- 29. 3 major changes: Distance bet node of Ranvier is altered Myelin covering axon is thinner Slitting & crossing of axons
- 30. Factors affecting regeneration: Site of lesion Duration of injury Age Nutrition Blood supply Associated injury/ infection
- 31. Gangliosides: agents used invivo for aiding regeneration 2 properties: Neuronotrophic Neuritogenic Bovine origin- used in peripheral neuropathies
- 32. Immunomodulators: Nerve injury- release of nerve proteins – ‘foreign antigens’- leads to neuritis. Azathioprine, Hydrocortisone- aid nerve regen.
- 33. Growth factors: NGF- nerve growth factor NPF- neurite promoting factor NGF: inc. axonal branching inc. dentritic branching prevention of death of neurons
- 34. Grading system of facial nerve HOUSE & BRACKMAN’S: 1984- Facial Nerve Disorder Committee of American Academy of Otolaryngology Grade 1: normal Grade 2: mild dysfunction slight weakness normal symmetry & tone motion in forehead- moderate to good, eye closure- complete slight asymmetry of mouth
- 35. Grade 3: moderate dysfunction no disfiguring difference Motion of forehead- slight to moderate Weakness of angle of mouth Eye closure- incomplete Grade 4: moderately severe dysfunction obvious asymmetry Rest- normal symmetry & tone No motion in forehead Eye closure- complete Mouth movement with max effort
- 36. Grade 5: severe dysfunction barely perceptible motion at rest Forehead motion-none Eye closure- incomplete Very slight mouth movement o Grade 6: total paralysis no movement
- 37. Causes of facial palsy BIRTH: Forceps delivery Moebius syndrome Dystrophia myotonica TRAUMA Accidental Skull base # Penerating injury to middle ear Barotrauma Scuba diving Iatrogenic Mastoid surgery Parotid surgery Postaural LA Antitetanus serum Rabies vaccine Embolization
- 38. INFECTIONS: Bacterial Malignant otitis externa Otitis media Tuberculosis Botulism Lyme disease Mostoiditis Viral Herpes zoster cephalicus Poliomyelitis Encephalitis Fungal Mucormycosis NEOPLASTIC Cerebellopontine angle tumours Vestibular schwannoma Facial nerve tumours Cochlear neuromas Meningioma Ependymoma Arachnoid cyst Temporal bone tumours Primary Glomus jugulare Von Recklinghausen’s disease Hans- Schuller- Christian disease Secondary Teratoma Leukemia Sarcoma
- 39. Parotid tumours Benign Pleomorphic adenoma Adenolymphoma Oxyphil adenoma Malignant Mucoepidermoid carcinoma Acinic cell carcinoma Adenocarcinoma Eoidermoid carcinoma Neurological Opercular syndrome Milliard- Gabler syndrome Encephalitis Multiple sclerosis Myasthenia gravis Charot- Marie- Tooth disease Miscellaneous Toxic Tetanus Diphtheria Metabolic Diabetes
- 40. Testing of facial nerve Depends upon: Determining degree of axonal degeneration- “ electrodiagnosis” Function of accessory branches – “ topognosis”
- 41. Topognostic tests Lacrimation tests ( Schirmer’s test) Stapedial reflex Salivary flow test Sensation test CT Prognostic tests EMG NET NCT MST ENoG Diagnostic assessment Blink reflex EMG EnoG Intraoperative monitoring Electrically evoked potential Mechanically evoked potential
- 43. Topognostic tests Lacrimal flow test: ( Schimer’s test) Tschiassny ( 1953) Filter paper 5cmx 0.5cm Lower conjuctival fornix- 5mins <30% / 25mm
- 45. Salivary flow test: Magielski & Blatt (1958) No. 50/60 polyethylene catheter- Whartons papilla Lemon drops- suck for 1 min 1-5 mins- monitor <25%
- 46. Stapedial reflex: Objective test Called ‘ Otologists EMG ‘ Taste sensation Ant 2/3rd
- 47. Electrodiagnostic tools 2 types: A) Orthodromic conduction tests: nerve stimulated proximally, muscle response distally B) Antidromic conduction test: nerve stimulated in retrograde manner Disadv- artifacts, difficult to detect
- 48. EMG: Weddell & colleagues (1944) Measures electric response during needle insertion at rest & voluntary movement ( Crumley, 1982)
- 49. Merits: Detect subclinical evidence of early regeneration Differentiate birth trauma from embryological etiology Determine completeness of neural blockade Demerits: Use only after 14- 21 days of nerve injury False response
- 50. Nerve conduction time: ~ to EMG Tests latency response of a muscle EMG- stimulates nerve at stylomastoid foramen. ‘latency’- time bet onset of stimulus & onset of response Reliable
- 51. Nerve excitibility test: Stimulating nerve at stylomastoid foramen- twitch reflex Easy to perform, easily available, inexpensive. Difference of 3.5 mA bet sides- poor prognosis. Dermertis: small fibers- higher threshold 50% fibers have to be lost – best results
- 52. Maximal stimulation test: Modified NET Uses max stimulation to peripheral branches Current 5mA- increased slowly Electroneurography: Esselen, 1977 Bipolar electrodes used 2 techniques: Standard lead placement ( Hughes, 1981) Optimized lead placement ( Kartush, 1985) OPL more reliable- better subject tolerance Alar nasi- optimum site
- 53. Magnetic stimulation: Barker (1985) Stimulate motor cortex by time varying magnetic fields to induce electrical depolarization. At REZ- by transcranial penetration Blink reflex: Overend (1896) Tapping glabellar surface Electrically- stimulating supraorbital foramen- response of orbicularis oculi Trigeminal- afferent, facial- efferent Test for intracranial & intratemporal portion
- 54. Bell’s palsy Sir Charles Bell, 1829 Def: “ acute idiopathic lower motor neuron palsy of facial nerve, usually unilateral, self- limiting, non-progressive, non-life threatening, spontaneous remitting by 4-6 months, always by 1 yr.
- 55. THEORIES: Vascular ischemia theory Viral theory Hereditary theory
- 56. Vascular ischemia theory: Dec circulation to facial nerve. Interruption of major vessels/ sec to compression within fallopian canal Primary: vasospasm of blood vessels Opposition: rich supply from stylomastoid & petrossal vessels. Proponents: lack of anastomosis, dec vascularity of horizontal segment, embolization of middle meningeal artery
- 57. Secondary: arterial constriction- capillary dilatation- inc permeability- transudation Capillary dilatation- ischemic damage/ reflex from fall in venous pressure Pressure from transudate- walls of lymph capillaries- closed by compression. Fluid accumulates- compressed venules & capillaries within fallopian canal- “ zonal ischemia” Teritiary: strangulation effect produces residual facial paresis.
- 58. Viral theory: Titer to herpes simplex virus/ herpes zoster Adour et al- acute benign cranial polyneuritis caused by reactivation of herpes simplex virus. Virus replicates in ganglion cells causing local damage & hypofunction of nerves. Passes down to axons- Radiculitis Infects schwann cells causing inflammation & autoimmune response Lymphocytic infiltration- fragmentation of myelin- demyelination
- 59. Hereditary theory: Osteoporosis- fallopian canal – abnormal small diameter Prone to ischemia/ viral infections
- 60. C/F: h/o exposure to cold draught wind Pain in post auricular region Inability to gargle Facial asymmetry Deviation to opp. side Acute & unilateral Numbness/ weakness Dec lacrimation & salivation 90% absence of stapedial reflex Chorda tympani- red on otoscopic exam. Within 10 days of onset
- 61. Upward movmnt of eyeball on attempting to close eye- “Bell’s phenomenon” Epiphora Collection of food in cheek Inability to blow/ whistle Loss of taste Hyperacusis – involvement of chorda tympani
- 62. Management: Medical: Steroids: prednisolone, 60 mg for 3 wks (tapering) Acyclovir- 200- 400mg, 5 times /day Vasodilators: xanitol nicotinate, ascorbic acid, multivitamins (B1,B6, B12) Eye care Active/ passive physiotherapy
- 63. Surgical decompression: Criteria ( Marsh & Coker) Complete denervation Paralysis >4-6 wks Incomplete return of function in 60 days Recurrent facial palsy NET diff of 3.5mA bet both sides
- 65. Facial nerve in Temporal bone fractures Longitudinal Transverse Mixed
- 66. Longitudinal fractures: Results from blows ( temporal/ parietal) Fracture line: ant to otic capsule, involves external & middle ear Bleeding from ear Conductive hearing loss- ossicular disruption Does not involve otic capsule No sensorineural hearing loss Facial nerve canal spared. Delay onset- nerve edema
- 67. Transverse fractures: Frontal/ occipital blows Fracture line: through otic capsule Damages inner ear Hemotympanum Tympanic membrane intact- no bleeding from ear Sensorineural hearing loss Tinnitus, nausea, vomiting, vertigo, facial palsy
- 68. Mixed fractures: Comb of longitudinal & transverse Fragments of bone lies over facial nerve Comminuted fractures Brain edema/ pneumocranium Prolonged unconsciousness CSF leakage
- 69. C/F: Deafness- conductive/ sensorineural/ mixed Hemotympanum/ bleeding from ear Facial palsy- lower motor neuron type Vertigo- subside in 2-3 wks Lateral rectus palsy- on opp side, intraorbital hematoma CSF otorrhea & otorhinorrhea Discoloration of skin over mastoid- Battle’s sign Unconsciousness, neurological deficit.
- 70. Management: HRCT X rays Facial nerve decompression Canal wall down technique
- 71. Iatrogenic injury of facial nerve Methods to restore functional continuity: a) Nerve intact but edematous- nerve decompression , widening of fallopian canal- slitting of nerve sheath- drain intraneural hematoma. b) Partial cut- suturing with 8-0 nylon/prolene
- 72. c) Complete transection- length of damage < 5mm, re-routing, end to end anastomosis. d) Complete transection- cut ends are apart- nerve grafting with greater auricular nerve. keep upper end of anastomotic site more stable- axonal nerve regeneration from above downwards. Remove 1mm of neurilemmal sheath at anastomotic ends, bevel cut ends.
- 73. Complete transection with upper stump not available for re-innervation, duration of palsy> 18 months – “facio-hypoglossal anastomosis” Disadv: mass movmnt, lack of emotion, paralysis of tongue. Regeneration- 1mm/ day
- 74. Other techniques: Sling operation using tendon/fascia Free neurovascular repair Muscle transposition Protection of eye: Dark goggles Tarsorrhaphy Gold weight for upper eyelid Eyelid spring
- 75. Technique of nerve repair: Suturing: No loss of facial nerve segment Bleeding granulation- difficult identification 8-0 nylon/prolene- no knots Tagged under nerve sheath- reposited back over nerve Supported by temporalis fascia graft. Serves as splint- nerve ends stable, in approximation Scaffolding- guide cut ends to re-unite
- 77. Choice of procedure Dynamic & neuronal reconstruction Static methods
- 78. Dynamic reconstruction NEURAL REPAIR: 1) Direct nerve repair & grafting: Direct approximation/ autogenous nerve grafting Main trunk re-approximated with no tension Autografting- branches from cervical plexus ipsilateral/ contralateral Sutured to terminal branches Alternative- sural nerve Recovery- 6 to 24 months
- 80. 2) Cross- face nerve grafting ( facio-facial anastomosis) From non- paralysed side by sural nerve grafts. Length of graft 6-8 cm 2 stage procedure Operative technique: FN of non- paralysed side ( buccal branches) sutured microsurgically to branches on paralysed side using sural nerve graft.
- 81. Disadv: Long operating time Muscles undergo atrophy Only 50% fibers from normal side can be used 2 suture lines of each graft
- 82. 3) Nerve crossover: Adv: only one anastomosis Used when direct anastomosis is not feasible Nerves used: glossopharyngeal, accessory, phrenic, hypoglossal Hypoglossal- facial cross over- most popular. Adv: simple, single suture line, powerful innervation Disadv: uncooradinated movmnts, loss of emotion, loss of function of donor nerve.
- 84. MUSCLE REPAIR: Muscle transfer: Long standing muscle atrophy To mimetic muscles In combination with nerve graft Masseter & temporalis- commonly used
- 85. a) Masseter muscle transposition: Ideally suited to give motion of lower face ( De Castro & Zani 1993) 3 muscle slips sutured to dermis of lower lip, oral commissure & upper lip. Over correction- must be accomplished
- 87. b) Temporalis muscle transposition: Facilitate grater excursive movements. Adaptibility to orbit 2 temporal musculofacial trips- reconstruct upper lip, lower lip & eyelids Adv: good muscle bulk, compensate lack of fullness Direct muscular insertion- greater range of motion. Best suited for ocular paralysis Transfer muscles- from trigeminal nerve Facial movmnt on chewing, clenching & moving mandible.
- 89. c) Free muscle graft: Muscle denervated 14 days before transplantation Full length of muscle is preserved Denervated mucle is placed in direct contact with normal vascularized muscle at recepient site.
- 90. d) Free microneurovascular muscle transfer: In combination with cross- face nerve graft/ ipsilateral nerve graft/ split hypoglossal anastomosis. Provide new, vascularized muscle of face. Adv: transferred muscle reinnervated by cross face nerve graft.
- 92. Choices of donor muscles: Gracilis muscle Pectoralis minor Latissimus dorsi Serratus Rectus abdominis Platysma
- 93. 2 stage: 1st stage- one/ more cross face nerve graft 2nd stage- 9-12 months later vascularized muscle transferred, neuronal element sutured to distal end of cross face nerve graft Disadv: 2 donor site scars 2 yrs elapse before return to normal movmnt
- 94. Static methods of reconstruction a) Suspension : fascia lata sling to support orbicularis oris & lower eyelid b) Mechanical devices: gold weights, springs, magnets for eye closure c) Selective neurectomy: sectioning of intact FN d) Selective myectomy
- 96. e) Surgery for correction to camouflage deformity: excision of nasolabial skin, face lift, brow lift f) Botulinum toxin: interfere ACH release from motor nerve endplates causing paralysis, 4-6 months
- 97. Fascio- hypoglossal jump anastomoses End – to end anastomosis- no epineurium. Skin incision from insertion of lobule of ear, curved backward & downward distance of 4 cm. Greater auricular nerve- identified, dissected, obtain graft of 6cm length. FN stump identified & transected near stylomastoid foramen. Hypoglossal nerve- identified, beneath digastric muscle
- 100. Distal end of graft of greater auricular nerve interpositioned, end- to end to distal stump of FN. Other end end- to side to obliquely transected hypoglossal nerve. 10-0 nylon sutures used- tension free approx.