Bell's Palsy

Incidence

• 20 to 30 cases per 100,000 people per year
• 60 to 75 per- cent of all cases of unilateral facial paralysis
• sexes are affected equally
• median age at onset is 40 years, but the disease may occur at any age

Outcomes

• Takes 3 days for maximal symptoms
• Up to 30% may have some residual symptoms at 6 months
• 7-12% of patients have a recurrence
  

Other causes of acquired peripheral facial weakness (much less common)

• diabetes mellitus
• hypertension
• HIV
• Lyme disease
• Ramsay Hunt syndrome (facial palsy with zoster oticus caused by varicella–zoster virus - may be more severe with a higher likelihood of permanent sequelae and multiple cranial nerve involvement)
• sarcoidosis
• Sjögren’s syndrome
• parotid-nerve tumors
• eclampsia
• amyloidosis

Other patterns of facial palsy

• Recurrent facial palsy
• Ipsilateral - concern for schwannoma of facial nerve or nearby neoplasm compressing (parotid gland, temporal bone)
• Alternating - usually benign and may occur in up to 14% of patients with Bell's Palsy
• Bilateral facial palsy
• Neurological (Guillain-Barre), neoplasm (lymphoma)
• Infectious (Lyme), autoimmune and granulomataous diseases (Sarcoid)
  

Forehead sparing

• A peripheral lesion should have upper and lower facial weakness
• A central lesion should have only lower facial weakness
• May be accompanied by numbness - etiology unclear as Facial nerve (7th nerve) is motor
  

Treatment

• Artificial tears to lubricate the cornea and may need to have the eye taped shut to prevent drying and infection
• Valacyclovir (1 g twice daily for seven days) or famciclovir (750 mg three times daily) or acyclovir (800 mg five times daily) and oral prednisone (1 mg per kilogram per day for seven days)
• 80 to 100 percent regain excellent function