Facial Paralysis

I. UMN Facial Paralysis

• Caused by lesions in the brain above the facial nucleus.
• Lesion Site: Supra-nuclear (from cerebral cortex to the facial nucleus)
• Causes:
  1. Trauma
  2. Inflammation (e.g., encephalitis, brain abscess)
  3. Brain Tumors
  4. Cerebral Vascular Accidents (thrombosis, hemorrhage, embolism)
  5. Degenerative Diseases (Multiple Sclerosis)

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II. LMN Facial Paralysis

• Resulting from lesions in the facial nucleus or the facial nerve itself.

A) Intracranial Causes

1. Lesion in the pons affecting the facial nucleus (similar causes to UMNL)
2. Lesion at the cerebello-pontine angle (e.g., Acoustic Neuroma, arachnoid cyst, congenital cholesteatoma)

B) Intra Temporal (Otogenic) Causes

(During its course in the temporal bone)

1. Idiopathic: Bell’s palsy
2. Traumatic:
   • Accidental (e.g., birth trauma, transverse temporal bone fracture)
   • Operative (e.g., during mastoidectomy)
3. Inflammatory:
   • Bacterial (secondary to otitis media or malignant otitis externa)
   • Viral (e.g., Herpes Zoster Oticus/Ramsay Hunt Syndrome)

C. Extracranial (Infratemporal) Causes

1. Malignant parotid gland tumors
2. Traumatic:
   • Accidental
   • Surgical (e.g., during parotidectomy)
   • Birth trauma due to forceps pressure over the stylomastoid foramen (usually incomplete and transient)
3. Inflammatory:
   • Peripheral neuritis (viral or diabetic mellitus)

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UMNL vs. LMNL

Feature	UMNL	LMNL
Affected Area	Lower half only (upper half spared due to bilateral innervation)	Whole face
Movements	Emotional (involuntary) preserved	Both voluntary and emotional movements lost
Paralysis Type	Spastic paralysis with no muscle wasting or degeneration	Flaccid paralysis with muscle wasting and degeneration
Associated Symptoms	Usually accompanied by hemiplegia	No hemiplegia

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