• Peripheral facial nerve weakness (cranial nerve VII) may be partial or complete, usually unilateral

ICD-9 Codes

  • 351.0 Bell’s palsy


  • Highest incidence of Bell’s palsy between ages 15-45 years
  • Annual incidence 25-32 per 100,000

Causes and risk factors

  • Idiopathic
  • Infections may be responsible for many cases

          -Herpes simplex virus

          -Varicella-zoster virus reactivation

          -Lyme disease

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  • Diabetes mellitus 
  • Third trimester of pregnancy 


  • Corneal drying, corneal abrasion
  • Chronic spasm of facial muscles (synkinesia) or blepharospasm
  • Anxiety and depression related to appearance


  • Symptoms

          -Facial weakness

          -Unilateral loss of taste sensation

          -Hyperacusis (sensitivity to sound)

          -Face feels stiff or pulled to one side

  • Abrupt onset, maximum weakness by 48 hours
  • Pain behind or in front of ear may precede onset of weakness
  • Questioning about earlier development of rash should be done if patient has been in region endemic for Lyme disease or has had a tick bite
  • Impact

          -Difficulty with eating or drinking

          -Difficulty with facial expressions



  • Peripheral facial nerve weakness

          -Can involve all muscles of facial expression

          -Greater involvement of lower face

  • Look for manifestations of Lyme disease (erythema migrans)
  • Clues suggesting peripheral lesion of Bell’s palsy rather than central lesion (such as stroke) include Inability to raise eyebrow to wrinkle forehead

          -Involvement of eye closure on ipsilateral side

          -Hyperacusis due to peripheral nerve involvement of stapedius muscle

          -Sense of taste may be decreased on ipsilateral side

  • Check external ear canal on affected side for vesicles implicating Ramsay Hunt syndrome
  • Look for other neurologic signs to suggest central nervous system cause such as stroke

          -Other cranial nerve deficits

          -Arm and/or leg paralysis


  • Additional cranial nerve deficits may be seen in Bell’s palsy

Rule out

  • Secondary causes of peripheral facial weakness


  • Lyme disease
  • Ramsay Hunt syndrome (zoster of geniculate ganglion)
  • Infectious mononucleosis
  • HIV infection 

          -Tumors including

  • Parotid gland tumors
  • Cholesteatoma
  • Recurrent skin cancer

          -Occult malignancy of facial nerve

          -Guillain-Barre syndrome


  • Central nervous system diseases
  • Bilateral facial paralysis (facial diplegia) more likely in Lyme disease

          -Acute inflammatory polyradiculoneuritis (Guillain-Barre syndrome)

          -Myasthenia gravis


Testing to consider

  • No testing indicated in most cases of peripheral facial palsy
  • MRI with contrast can rule out tumor, stroke, multiple sclerosis, or other structural lesions
  • Lyme titer


  • Most patients recover completely, especially if partial paralysis or younger age

          -Onset of recovery within three weeks in 85% and within three to five months in 15%

          -Remission within 3 weeks in 55% and after three to six months in an additional 15%

          -Full recovery less likely with increasing age

  • 90% children <14 years old
  • 84% ages 15-29 years
  • 75% ages 30-44 years
  • 64% ages 45-59 years
  • 36% adults >60 years old
  • Diabetes and pregnancy associated with lower recovery rate
  • Four clinical factors may be associated with unfavorable outcome in Bell’s palsy patients treated with prednisolone

          -Duration between onset and treatment longer than seven days

          -Severe facial paralysis

          -Hearing defect

          -History of recurrence


  • Corneal protection may include lubrication (eyedrops or ointment) and eyelid taping
  • For hyperacusis, earplug may be helpful
  • Corticosteroids

          -Hasten recovery and increase rates of complete recovery

          -May be ineffective during pregnancy

  • Antivirals have inconsistent evidence for Bell’s palsy but no benefit in highest-quality trials
  • Vitamin B12 intramuscularly may be beneficial
  • Acupuncture might improve outcomes

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This article originally appeared on Cancer Therapy Advisor