Facial Nerve Paralysis

Facial Nerve Anatomy & Basics - Nerve Nuances

• Nuclei (Pons): Motor, Sup. Salivatory (parasymp), NTS (sensory).
• Functions: Motor (face), Glands (lacrimal, submandibular/lingual), Taste (ant. 2/3 tongue). 📌 FACE-L: Facial expression, Acoustic reflex, Chorda, Eye closure, Lacrimation.
• Course: CPA → IAM → Facial Canal (geniculate ganglion) → Stylomastoid foramen.
• Branches (in canal):
  • Greater Petrosal (lacrimation)
  • N. to Stapedius (stapedial reflex)
  • Chorda Tympani (taste, salivation)

⭐ Labyrinthine segment: narrowest part of facial canal (~0.68mm), prone to compression in Bell's Palsy.

Causes & Localization of FNP - Culprit Countdown

• Common Culprits (Causes):

  • Idiopathic: Bell's Palsy (most frequent, >70%).
  • Infections: Ramsay Hunt (VZV), Otitis Media, Lyme.
  • Trauma: Temporal bone # (longitudinal/transverse).
  • Neoplastic: Acoustic neuroma, parotid tumors.

• Pinpointing the Lesion (LMN Topodiagnosis):

  • UMN vs LMN: UMN spares forehead; LMN affects entire hemiface.

  

⭐ Bell's Palsy is a diagnosis of exclusion; always rule out sinister causes like tumors, especially in atypical/progressive FNP or recurrent FNP on the same side.

Clinical Evaluation & Grading - Face Facts

• History: Onset (sudden?), otalgia, vesicles (HZV), hearing loss, vertigo, trauma.
• Exam:
  • Otoscopy: Check for vesicles, AOM.
  • Differentiate UMN (forehead spared) vs LMN paralysis.
  • Assess facial zones: Forehead, Eyes (Bell's phenomenon, closure), Mouth (smile, pucker).
  • 
• Grading: House-Brackmann (HB) Scale:
  • I: Normal
  • II: Mild
  • III: Moderate
  • IV: Mod-Severe
  • V: Severe
  • VI: Total

⭐ In LMN paralysis, Bell's phenomenon (upward outward rolling of eyeball on attempted eye closure) is present.

Key Syndromes & Management - Nerve Navigators

• Bell's Palsy: Most common, idiopathic LMN type.
  • Sudden, unilateral.
  • Rx:
    • Corticosteroids (Prednisolone 1 mg/kg/day, max 60-80 mg, 7-10 days, taper). Start <72h.
    • +/- Antivirals (Valacyclovir 1g TID / Acyclovir 400mg 5x/day, 7 days) if severe.
    • Eye care (lubrication, patching).
• Ramsay Hunt Syndrome (Herpes Zoster Oticus): VZV origin.
  • Facial palsy + otalgia + vesicles (ear/mouth). 📌 Pain, Palsy, Pox.
  • Rx: Antivirals + Corticosteroids. Worse prognosis vs Bell's.
• Other Causes: Trauma (e.g., temporal bone #), Tumors, Infections (e.g., AOM, Lyme), Systemic (e.g., Sarcoidosis, GBS).
• General Rx:
  • Grade severity (House-Brackmann).
  • Corneal protection.
  • Physiotherapy.
  • Surgery (select cases: trauma, unresponsive Bell's).

⭐ For Bell's Palsy, corticosteroids initiated within 72 hours of onset yield maximal benefit.

Prognosis & Complications - Future Face

• Prognosis: Varies by cause, severity (House-Brackmann). Bell's: 85% recovery. ENoG >90% degeneration = poor.
• Complications:
  • Corneal ulcers (exposure keratitis)
  • Synkinesis (miswiring)
  • Crocodile tears (gustatory lacrimation)
  • Contractures

⭐ Synkinesis, due to aberrant nerve regeneration, is a common long-term complication.

High‑Yield Points - ⚡ Biggest Takeaways

• Bell's palsy: most common LMN facial paralysis, often idiopathic/viral (HSV-1).
• Ramsay Hunt syndrome (Herpes Zoster Oticus): facial palsy, ear pain, vesicles in auricle/EAC.
• House-Brackmann grading is standard for facial nerve function assessment.
• UMN lesions spare the forehead (bilateral innervation); LMN lesions affect the entire hemiface.
• Temporal bone fractures, especially transverse type, carry a high risk of facial nerve injury.
• Management: Corticosteroids (e.g., prednisolone) are mainstay for Bell's palsy; antivirals controversial. Eye care is crucial to prevent corneal complications.