Facial Nerve Injury

CLASSIFICATION OF NERVE INJURY:
  • Sunderland Nerve Injury Classification:
Class I (Neuropraxia)
  • Axon remain intact
  • Conduction block caused by cessation of axoplasmic flow
  • Full recovery
2. Class II (Axonotmesis)
  • Axons are disrupted
  • Endoneural tube still intact
  • Full recovery expected
3. Class III (Neurotmesis)
  • Neural tube is disrupted
  • Poor prognosis
  • If regeneration occurs, high incidence of synkinesis (involuntary movement of muscles associated with voluntary movement other muscles )
4. Class IV
  • Epineurium remains intact
  • Perineurium, endoneurium, and axon disrupted
  • Poor functional outcome with higher risk for synkinesis
5. Class V
  • Complete disruption
  • Little chance of regeneration
  • Risk of neuroma formation
House-Brackmann Grading System
  • Used for clinical assessment of patient with facial nerve paralysis.

Grade Characteristics
I.Normal Normal facial function in all areas
II.Mild Dysfunction Slight weakness noticeable on close inspection
Forehead - Moderate-to-good function
Eye - Complete closure with minimal effort
Mouth - Slight asymmetry
III.Moderate Dysfunction Obvious asymmetry
Forehead - Slight-to-moderate movement
Eye - Complete closure with maximum effort
Mouth - Slightly weak with maximum effort
IV.Moderately
Severe
Dysfunction
Obvious weakness and/or disfiguring asymmetry
Forehead – No motion
Eye - Incomplete closur
eMouth - Asymmetric with maximum effort
V.Severe Dysfunction Only minimal motion seen.At rest, asymmetry
Forehead – No movement
Eye - Incomplete closure
Mouth - Slight movement
VI. Total Paralysis No movement
CAUSES OF FACIAL NERVE PARALYSIS:
  • Supranuclear Lesions :
  1. Congenital abnormalities, stroke, malignancies, trauma , vascular conditions and other causes .
  2. Only lower part of the opposite side of the face is paralyzed
  3. The upper part with the frontalis and orbicularis oculi escapes due to bilateral representation in the cerebral cortex.
  • Infranuclear Lesions :
  1. Malignancy (parotid gland as well as tumors of adjacent structures) , trauma, infections, Bell’s palsy, osteopetrosis and iatrogenic causes .
  2. The whole of the face of the same side gets paralyzed
  • FRACTURES:
  1. Facial nerve palsy occurs in 20% of longitudinal temporal bone fractures and 50% of transverse temporal bone fractures.
  2. Facial nerve palsy is also seen in the fracture of middle cranial fossa
  • IATROGENIC
  1. Mastoidectomy commonly
  2. While doing posterior tympanotomy through the facial recess there are chances of injury to the Chorda tympani & Vertical descending part of facial nerve but not Facial nerve horizontal part
  3. Most common nerve injured in face lift surgery is Frontal branch of facial nerve
  • INFECTION:
  1. Facial nerve palsy is seen in Malignant otitis externa & also in Chronic suppurative otitis media.
  2. Herpes zoster infection recurrence causes facial nerve palsy.
SIGNS & SYMPTOMS OF FACIAL NERVE PARALYSIS:
  • The symptoms according to the level of injury of facial nerve.
  1. At Internal Auditory Meatus:(injury is at Geniculate ganglion)
  2. Loss of lacrimation, stapedial reflex(seen in facial nerve swelling within facial canal ), taste from most of anterior two-third of tongue, lack of salivation and paralysis of muscles of facial expression.
  3. b. Below Geniculate Ganglion:(at chorda tympani)
  4. Loss of stapedial reflex i.e.inability to dampen loud noises , taste from anterior two third of tongue, lack of salivation and paralayis of facial expression muscles. c. Region Below Stylomastoid Foramen
  5. Paralysis of facial expression muscles.(Loss of corneal reflex at side of lesion)
Exam Question
  • In supranuclear lesion of facial nerve lower part of the opposite side of the face is paralyzed.
  • A Swelling of the facial nerve within the facial canal resulting from compression of nerve due to an inflammatory process in the temporal bone results in paralysis of stapedius muscle
  • Iatrogenic traumatic facial nerve palsy is most commonly caused du­ring Mastoidectomy
  • A patient with a facial nerve paralysis suffers from inability to dampen loud noises due to denervation of stapedius muscle
  • Facial nerve palsy occurs in 20% of longitudinal temporal bone fractures and 50% of transverse temporal bone fractures.
  • Facial nerve palsy is seen in the fracture of middle cranial fossa
  • While doing posterior tympanotomy through the facial recess there are chances of injury to the Chorda tympani & Vertical descending part of facial nerve but not Facial nerve horizontal part
  • Facial nerve palsy is seen in Malignant otitis externa
  • Facial nerve palsy is seen in Chronic suppurative otitis media(CSOM)
  • Lacrimation is affected when facial nerve injury is at Geniculate ganglion
  • In oedma of facial nerve at the level of geniculate ganglion hyperacusis, loss of lacrimation and loss of taste sensation in the anterior 2/3rd of the tongue are seen In Dryness of mouth with facial nerve injury site of lesion is at Chorda tympani Nerve
  • Level of injury of facial nerve region below Stylomastoid foramen Loss of corneal reflex
  • Most common nerve injured in face lift surgery is Frontal branch of facial nerve
Don't Forget to Solve all the previous Year Question asked on Facial Nerve Injury