Facial nerve & Bell’s palsy

Facial nerve in ENT region

• It enters ear through internal acoustic meatus
• In the ear it passes through fallopian canal
• Comes out through the stylomastoid foramen
• 3 segments in the canal:
  1. Labyrinthine segment:
     • Narrowest & shortest segment: Most vulnerable to ischemia
  2. Horizontal segment
  3. Vertical segment.

• 3 branches of facial nerve in the ear:
  1. First genu: Greater superficial petrosal nerve: Supplies lacrimal gland
  2. Second genu: Nerve to stapedius
  3. Vertical segment: Chorda tympani nerve: Supplies anterior 2/3rd of tongue (taste sensation).

Bell’s palsy

• Idiopathic LMN type sudden onset facial palsy
• HSV has ?probable etiological role
• C/F:
  1. Inability to elevate the eyebrows
  2. Paralysis of forehead muscles
  3. Inability to close the eyelid: Exposure keratitis
  4. Drooping of the angle of the mouth to the affected side: saliva dribbles through the angle of mouth
  5. Hyperacusis (loss of stapedial reflex).
• Rx:
  • DOC: Oral steroids for 3 wk
  • May give Acyclovir: If pt presents within 3 days of onset
  • Artificial tear drop
  • Prevention of exposure keratitis:
    • Patching
    • Suturing upper and lower eyelid: Tarsorrhaphy.
• Outcome:
  • Recovery is seen in 85% cases
  • Treatment in failed cases: