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Condition/Disorder Synonyms

  • Facial palsy
  • Peripheral facial paralysis

ICD-9-CM Code

  • 351.0 Bell’s palsy

ICD-1-CM Code

  • G51.0 Bell’s palsy, facial palsy

Key Features


  • Paralysis or weakness of muscles on one side of face
  • Sudden onset, often overnight
  • Damage to the 7th cranial (facial) nerve that controls muscles on one side of the face, causing that side of face to droop
  • Nerve damage may affect sense of taste, production of tears and saliva


  • Lower motor neuron (LMN) disease
  • Diagnosis usually made by history and clinical examination

General Considerations

  • Afflicts approximately 40,000 Americans each year


  • Equally likely in men and women
  • Can present at any age, but less common before age 15 years or after age 60
  • More prevalent in people with diabetes or upper respiratory ailments, such as flu or cold
  • More likely in pregnant women

Clinical Findings

Signs and Symptoms

  • Sudden weakness or paralysis on one side of face that causes it to droop (main symptom)
  • Difficulty closing eye on affected side
  • Drooling
  • Dry mouth
  • Eye problems, such as excessive tearing or dry eye
  • Loss of ability to taste
  • Pain in or behind ear
  • Facial numbness on affected side
  • Increased sensitivity to sound
  • Headache
  • Facial twitch
  • Inability to smile or make facial expressions

Functional Implications

  • Dry eyes
  • Eating
  • Hearing
  • Psychological impact

Possible Contributing Causes

  • The nerve that controls muscles on one side of the face is damaged by inflammation in most cases
  • Root cause of Bell's palsy is not clear
  • Most cases thought to be caused by the herpes virus that causes chickenpox and shingles, or Epstein-Barr virus that causes mononucleosis

Differential Diagnosis

  • Stroke
  • HIV infection
  • Herpes simplex virus
  • Infections
  • Lyme disease
  • Middle ear infection
  • Meningitis
  • Diabetes mellitus
  • Sarcoidosis
  • Brucellosis
  • Tumors
  • Ramsay Hunt syndrome

Means of Confirmation or Diagnosis

Laboratory Tests

  • Blood tests


Diagnostic Procedures

  • History and physical and neurological exam to check facial nerve function
  • If cause of symptoms is not clear, other tests are needed, such as
    • Nerve conduction test for facial nerve
    • Electromyography (EMG) for facial nerve

Findings and Interpretation

  • Facial muscle weakness or total paralysis (e.g., unable to frown) due ...

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