Facial Nerve Trauma Overview
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Questions and Answers

What characterizes a Grade II dysfunction in facial function?

  • Slight weakness noticeable on close inspection (correct)
  • No noticeable asymmetry
  • Severe asymmetry at rest
  • Complete eye closure with maximum effort

    • At what grade level does the eye show incomplete closure for the first time?

  • Grade V
  • Grade I
  • Grade IV (correct)
  • Grade II

    • Which statement accurately describes the mouth function in Grade III dysfunction?

  • Complete symmetry with maximum effort
  • Slightly weak with maximum effort (correct)
  • Disfiguring asymmetry at rest
  • Complete closure with minimal effort

    • What is the primary facial feature affected in Grade V dysfunction?

    <p>No movement in the forehead</p> Signup and view all the answers

    In which grade does facial dysfunction start to show an asymmetry that is described as obvious but not disfiguring?

    <p>Grade III</p> Signup and view all the answers

    What is the purpose of facial nerve testing?

    <p>To assess the degree of electrical dysfunction</p> Signup and view all the answers

    Which type of test can determine the site of facial nerve injury but does not predict recovery function?

    <p>Topographic test</p> Signup and view all the answers

    Which lesion site results in impaired lachrymation, stapedial reflex, taste, and salivation?

    <p>Lesion in CPA/IAM/labyrinthine segment</p> Signup and view all the answers

    What does a pure motor deficit indicate when assessing levels of facial nerve injury?

    <p>Intact lachrymation and stapedial reflex</p> Signup and view all the answers

    What does a Schirmer's test measure?

    <p>The amount of tear production</p> Signup and view all the answers

    What happens if there is a lesion between the nerve to stapedius and chorda tympani?

    <p>Intact lachrymation and stapedial reflex</p> Signup and view all the answers

    Which imaging test is rarely done for traumatic facial nerve injury but offers better visualization of soft tissue conditions?

    <p>Gadolinium enhanced MRI</p> Signup and view all the answers

    What is the primary benefit of identifying potential recovery of function in facial nerve injuries?

    <p>Guides treatment strategies</p> Signup and view all the answers

    What is a common effect of facial nerve injury caused by penetrating trauma to the temporal bone?

    <p>Facial nerve paralysis</p> Signup and view all the answers

    Which condition involves sensorineural hearing loss due to damage to the 8th cranial nerve?

    <p>Concussion</p> Signup and view all the answers

    What is the most common surgical procedure resulting in facial nerve paralysis?

    <p>Parotidectomy</p> Signup and view all the answers

    What percentage of cases involve unrecognized injury to the facial nerve during surgery?

    <p>80%</p> Signup and view all the answers

    Which type of fracture is classified as a transverse fracture in CT imaging?

    <p>Complex fracture</p> Signup and view all the answers

    Which are common symptoms associated with facial nerve injury?

    <p>Facial asymmetry and bruising</p> Signup and view all the answers

    How is sensorineural hearing loss characterized in cases involving concussion?

    <p>Caused by damage to the 8th cranial nerve</p> Signup and view all the answers

    What is a typical result of gunshot wounds to the temporal bone?

    <p>Facial nerve injury in extratemporal segments</p> Signup and view all the answers

    What grading system is used to assess facial movement after nerve injury?

    <p>House-Brackmann Grading</p> Signup and view all the answers

    What is a characteristic sign of haemotympanum during physical examination?

    <p>Bloody fluid drainage</p> Signup and view all the answers

    What is the primary purpose of the nerve excitability test (NET)?

    <p>To assess nerve conductivity by comparing current in paralyzed versus normal sides.</p> Signup and view all the answers

    Which statement about the maximal stimulation test (MST) is correct?

    <p>It cannot be performed accurately within the first 72 hours.</p> Signup and view all the answers

    What is one of the primary disadvantages of electroneurography (ENoG)?

    <p>It shows significant variability in test-retest results.</p> Signup and view all the answers

    During electromyography, what indicates a normal muscle activity?

    <p>Biphasic or triphasic potentials.</p> Signup and view all the answers

    How is the degree of facial nerve degeneration determined using ENoG?

    <p>By comparing the peak-to-peak response amplitude between sides.</p> Signup and view all the answers

    What does a response rated as 'markedly decreased' in the maximal stimulation test imply?

    <p>It suggests advanced degeneration and a poor prognosis.</p> Signup and view all the answers

    What is a significant drawback of the nerve excitability test (NET)?

    <p>It relies on a visual end point which is subjective.</p> Signup and view all the answers

    For a patient with 90% degeneration in ENoG, what surgical intervention is typically warranted?

    <p>Surgical decompression.</p> Signup and view all the answers

    Which of the following is considered a dynamic reconstruction procedure for facial nerve trauma?

    <p>Surgical procedures that enable active movement of muscles.</p> Signup and view all the answers

    What does a polyphasic potential recorded in electromyography indicate about muscle recovery?

    <p>Recovery signs are noted 6-12 weeks post-injury.</p> Signup and view all the answers

    What must be communicated to the patient before surgery regarding expected outcomes?

    <p>The patient's face will never be symmetrical or have a normal balance.</p> Signup and view all the answers

    What is considered a good prognosis if nerve response is assessed?

    <p>Response with 0.05mA.</p> Signup and view all the answers

    What should be done if loss of function is noted after surgery?

    <p>Wait 2-3 hours and then re-evaluate.</p> Signup and view all the answers

    What indicates the need for immediate surgical exploration in the case of facial nerve injury?

    <p>Complete paralysis following a temporal bone fracture.</p> Signup and view all the answers

    When should delayed exploration be performed for gunshot wounds?

    <p>After determining the extent of damage.</p> Signup and view all the answers

    What surgical approach should be used when the site of the facial nerve injury cannot be localized preoperatively?

    <p>Transmastoid/Middle cranial fossa approach.</p> Signup and view all the answers

    What is recommended to drain during the facial nerve decompression procedure if identified?

    <p>Hematoma.</p> Signup and view all the answers

    What is the purpose of neurolysis in facial nerve surgery?

    <p>To cut the epineural sheath near the injury point.</p> Signup and view all the answers

    Which of the following is an indication that further exploration is warranted?

    <p>Only distal response observed.</p> Signup and view all the answers

    What should be used to prevent thermal injury during facial nerve decompression?

    <p>Diamond burs and copious irrigation.</p> Signup and view all the answers

    Grade IV dysfunction presents with no forehead movement and incomplete closure of the eye.

    <p>True</p> Signup and view all the answers

    In Grade V dysfunction, there is complete closure of the eye with minimal effort.

    <p>False</p> Signup and view all the answers

    Grade II facial dysfunction shows a moderate difference in forehead movement.

    <p>False</p> Signup and view all the answers

    Obvious asymmetry becomes noticeable at rest in Grade III facial dysfunction.

    <p>True</p> Signup and view all the answers

    Grade VI dysfunction is characterized by significant functional weakness with apparent facial asymmetry.

    <p>False</p> Signup and view all the answers

    The mastoid segment of the facial nerve gives off branches to the cochlear nerve.

    <p>False</p> Signup and view all the answers

    Class IV Sunderland nerve injury classification indicates that the epineurium is disrupted while the perineurium remains intact.

    <p>False</p> Signup and view all the answers

    Temporal bone fractures are the leading cause of facial nerve paralysis after Bell's Palsy.

    <p>True</p> Signup and view all the answers

    The labyrinthine segment of the facial nerve runs in the widest portion of the internal auditory canal.

    <p>False</p> Signup and view all the answers

    In Sunderland Class II nerve injury, Wallerian degeneration occurs proximal to the site of injury.

    <p>False</p> Signup and view all the answers

    Study Notes

    Facial Nerve Trauma

    • Causes: Lacerations, fractures of the temporal bone, penetrating trauma (gunshot wounds), iatrogenic injury (surgery, forceps delivery),
    • Complications:
      • Sensorineural Hearing Loss
      • Haemotympanum (Conductive Deafness)
      • Facial Palsy
      • Vertigo
      • Labyrinthitis Ossificans
      • CSF Otorrhoea
    • Work-up:
      • History: Determine the mechanism of injury, time of onset, and associated symptoms.
      • Physical Exam: Complete head/neck examination, look for facial asymmetry, signs of injury (lacerations, hematomas, bruising), assess head/scalp, perform otoscopic examination and tuning fork tests.
      • Clinical Facial Nerve Test: Assess temporal, zygomatic, and mandibular branch function.
      • House-Brackmann Grading:
      • Radiologic Tests:
        • HRCT scans to evaluate bony pathology
        • MRI to visualize soft tissue
      • Facial Nerve Testing:
        • Topographic Testing: Assess nerve function of specific branches, help determine the site of injury (e.g., Schirmer's Test, Stapedial Reflex Test, Taste Test, Submandibular Salivary Flow Test)
        • Electrodiagnostic Testing: Utilize electrical stimulation to assess nerve conductivity and function.
          • Nerve Excitability Test (NET): Compare the amount of current needed for minimal muscle contraction between normal and paralyzed sides.
          • Maximal Stimulation Test (MST): Similar to NET but utilize maximal stimulation.
          • Electroneuronography (ENoG): Measures electrical activity and degeneration of the nerve.
          • Electromyography (EMG): Assesses the activity of the muscle itself.
    • Surgical Guidelines:
      • General:
        • Reconstruction: Can be dynamic (active muscle movement) or static (improve symmetry and reduce complications).
        • Informed Consent: Important to inform patients about the potential for asymmetry and lack of normal balance.
      • Iatrogenic Injury:
        • Transected Nerve: Explore 5-10mm of the involved segment.
        • Loss of Function Within 2-3 Hours Post-Surgery: Re-evaluate patient.
        • Complete Paralysis Following Temporal Bone Fracture: Immediate surgical exploration, likely nerve transection.
        • Partial or Delayed Loss of Function: High-dose steroids, ENoG at 72 hours, potential for exploration.
      • Penetrating Trauma:
        • Extratemporal: Exploration within 3 days of injury unless injury distal to the lateral canthus.
        • Gunshot Wounds: Delayed exploration is recommended.
    • Surgery for Acute Facial Nerve Trauma:
      • Facial Nerve Decompression:
        • Approach: Transmastoid/Middle cranial fossa approach (intact nerve) or transmastoid/translabyrinthine approach (absent nerve).
        • Procedure: Remove bone overlying the nerve, drain hematoma if identified.
      • Neurolysis: Cut epineural sheath on either side of the injury point to expose the nerve.
    • Important Points:
      • Thermal Injury: Use diamond burs and copious irrigation during surgery to prevent thermal nerve injury.
      • Prognosis: Partial paralysis generally has a better prognosis than total paralysis.
      • ENoG Results: >90% degeneration suggests surgical decompression.

    Facial Nerve Anatomy and Physiology

    • The facial nerve has an intracranial segment, which originates from the brainstem and runs through the internal auditory canal.
    • The facial nerve also has intratemporal segments, including:
      • Meatal: From the porus acusticus to the meatal foramen.
      • Labyrinthine: Fundus to the geniculate ganglion.
      • Tympanic: Geniculate ganglion to the second genu.
      • Mastoid: Second genu to stylomastoid foramen.
    • The facial nerve has extratemporal segments including:
      • From the stylomastoid foramen to the pes anserinus.
      • Branches into the temporal, zygomatic, buccal, marginal mandibular, and cervical segments.

    Facial Nerve Components

    • The facial nerve has motor, sensory, and parasympathetic components.
    • The motor component supplies the muscles of the facial expression, stylohyoid muscle, posterior belly of digastric, stapedius muscle, and buccinator.
    • The sensory component provides taste to the anterior two-thirds of the tongue and sensation to parts of the TM, the wall of the EAC, postauricular skin, and concha.
    • The parasympathetic component provides control to the lacrimal gland, seromucinous glands of nasal and oral cavities, and the submandibular and sublingual glands.

    Facial Nerve Injury Classification

    • Sunderland Nerve Injury Classification: (Class I - V)
      • Class I (Neuropraxia): Conduction block, full recovery expected.
      • Class II (Axonotmesis): Axon disruption, full recovery expected.
      • Class III (Neurotmesis): Disruption of the neural tube, poor prognosis, potential for synkinesis if regeneration occurs.
      • Class IV: Epineurium intact, perineurium, endoneurium, and axon disrupted, high risk of synkinesis.
      • Class V: Complete disruption, little chance of regeneration, potential for neuroma formation.

    Facial Nerve Trauma: Overview

    • Second most common cause of facial nerve paralysis after Bell's Palsy.
    • Can occur due to temporal bone fractures, accounting for 15% of all facial nerve paralysis cases.

    Temporal Bone Fracture

    • Makes up 5% of all trauma patients.
    • Three types (Ulrich 1926 classification):
      • Longitudinal: Most common, fracture line runs parallel to the petrous pyramid.
      • Transverse: Fracture line perpendicular to the petrous pyramid.
      • Mixed: Combination of longitudinal and transverse fractures.

    Testing Facial Function

    • Schirmer's Test: Evaluates lacrimal gland function, assessing the amount of tear production.
    • Stapedial Reflex: Evaluates the integrity of the facial nerve.
      • Sound directed to either ear causes bilateral contraction of the stapedius muscle.
      • Diagnostic for cochlear, retrocochlear, brainstem, and facial nerve pathology.

    Testing Taste

    • Taste Testing: Evaluates the anterior two-thirds of the tongue for sweet, salt, sour, and bitter tastes.
    • Electrogustometry: Electrical stimulation of the tongue for taste perception, provides a threshold measurement.

    Submandibular Gland Flow

    • Sialometry: Measures salivary flow through Wharton's duct using a polythene tube.

    Facial Nerve Surgical Guidelines:

    • Exploration is recommended for transected nerve during surgery or temporal bone fractures.
    • For iatrogenic injury, evaluate the nerve immediately after surgery, wait 2-3 hours for anesthesia to wear off, and then re-evaluate.
    • If complete paralysis persists with a known intact nerve, administer steroids and follow up with ENoG to assess degeneration.
    • Explore if ENoG shows >90% degeneration.
    • For penetrating trauma, explore the nerve within 3 days of injury unless it's distal to the lateral canthus.
    • For gunshot wounds, delay exploration to assess the extent of damage before surgery.

    Facial Nerve Decompression

    • Localize the injury preoperatively.
    • Approach:
      • Intact nerve: Transmastoid/middle cranial fossa approach.
      • Absent nerve: Transmastoid/translabyrinthine approach.

    Acute Facial Nerve Trauma

    • Neurolysis: Cut the epineural sheath to expose the nerve.

    Dynamic and Static Reanimation Surgery

    • Dynamic Surgery:
      • Regional muscle transfer: Use existing muscles in the head and neck to restore facial movement, such as the temporalis muscle transfer.
      • Microneurovascular free muscle transfer: Transfer a muscle from another region, such as the gracilis or latissimus dorsi muscle, to the face.
    • Static Reanimation Surgery: Improve facial appearance and function with procedures like:
      • Eye: Eyebrow repositioning, eyelid weight, tarsorraphy (eyelid suturing)
      • Nose: Static sling procedures for the corner of the mouth, cartilage grafts to widen the nasal cavity.

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    Facial Nerve Trauma PDF

    Description

    This quiz covers the causes, complications, and evaluation methods for facial nerve trauma. Learn about injury mechanisms and necessary examinations, including radiologic tests and functional assessments. Test your knowledge on facial nerve injuries and their implications.

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