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From: Eichhorst

FACIAL (VII) NERVE DISORDERS

Anatomy
Bell's palsy
Differential diagnosis

Facial nerve: Anatomy +


Facial nerve paralysis

  • Clinical features
    • Facial asymmetry
    • Eyebrow droop
    • Loss of forehead & nasolabial folds
    • Drooping of corner of mouth
    • Uncontrolled tearing
    • Inability to close eye
    • Lips not held tightly together: Difficulty keeping food in mouth
    • Facial muscle atrophy (Late)
  • Electrophysiology
    • EMG
      • Denervation
      • Synkinesis: Late
    • Blink reflex
      • Abnormal ipsilateral
        • R1 (early, disynaptic)
        • R2 (late multisynaptic) responses
      • Synkinesis (Late)
   

Bell's Palsy 8


Sir Charles Bell
Duchenne
Bell's palsy (19th cent)

Facial Paresis: Left
VII disorders: Differential Diagnosis

Melkersson-Rosenthal syndrome

  Chromosome 9p11; Dominant

Möbius & Congenital facial syndromes

Möbius syndrome: General Features4 Möbius & Congenital facial syndromes: Types



Facial Nerve Trauma & Tumors


Hemifacial Spasm

  • Onset
    • Adults
      • Typically 5th or 6th decade
      • Younger patients: Rule out brainstem disease, MS
    • Location: Orbicularis oculi muscle
    • More common in women
  • Contraction pattern
    • Synchronous contraction of facial nerve innervated muscles
    • Paroxysmal
    • Involuntary
    • Duration: Up to 1 minute
    • May persist during sleep
    • Usually unilateral
  • Weakness: Unusual
  • Triggers: Aggravating factors
    • Emotion
    • Fatigue
  • Causes
    • Recovery from Bell's palsy
      • Associated with synkinesis & contracture
    • Dolichoectatic brainstem artery
      • Frequency: 30%
      • Mechanism: Pressure on VII root entry zone
      • Vessels: PICA; AICA; Vertebral
    • Brainstem disease
    • Idiopathic
  • Course: Usually permanent without treatment
  • Electrophysiology
    • Brief bursts of action potentials
      • High frequency (150-400 Hz)
      • Normal motor units
    • Variable rhythm & amplitude
    • Lateral spread response3
      • Stimulation: Facial nerve branch
      • Response: In muscles not normally innervated by branch  
      • Related to cross transmission of facial nerve fibers
        • Location: Probably at site of compression
  • Treatment
    • Botulinum toxin
    • Microvascular decompression of VII nerve
      • Morbidity & Mortality 5%
    • Anticonvulsants


Bright 1831

Barker

T2 image: Brainstem & Cerebellum


MRA: AP view

Dolichoectasia of vertebral arteries
Deviation to right (Arrows)

Patient syndrome: R hemifacial spasm

Return to Cranial nerve disorders
Go to Facial Paralysis (Baylor)

References
1. Am. J. Hum. Genet., 1999;65:752-756
2. Neurology 2000;54:1217
3. Muscle Nerve 2002;25:845849
4. Neurology 2003;61:327333
5. Otol Neurotol 2003;24:948951
6. Otol Neurotol 2003;24:942947
7. J Neurol Neurosurg Psychiatry 2005;76:10171018
8. Cleve Clin J Med 2005;72:398-401
9. JNNP 2007 Online May
10. JNNP 2007;78:659-660
11. Lancet Neurology 2008;7:976-977 & 2008;7:993-1000
12. Otol Neurotol 2008;29:397-400
13. Otolaryngol Head Neck Surg 2007;137:858-861
14. Ann Neurol 2010;68:404408
15. Am J Human Genet 2012; Online July

8/13/2013