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Bell's Palsy

Bell's Palsy , defined as unilateral facial weakness, is a relatively common pediatric problem affecting children from infancy to adolescence. It is a diagnosis of exclusion and a careful history and physical examination will usually lead to a correct diagnosis. Bell's palsy is the most common cause of unilateral facial weakness.

Pathogenesis

Believed to be a post infectious allergic or immune neuritis affecting the facial nerve. There is no evidence of viral invasion of the nerve. Commonly associated viral illness include, EBV, Mumps, and Herpesvirus. Bell's palsy is also a common neurologic manifestation of Lyme's disease.

Clinical Manifestations- may be unnoticed by parents

  1. Weakness of upper and lower face
  2. inability to close eye
  3. Unilateral drooping of the corner of the mouth. May become evident when child smiles.
  4. loss of nasolabial fold
  5. normal sensation
  6. May loose taste of anterior 2/3 of tongue.
  7. Initial presentation may be pain around the ear or surrounding areas
  8. May be associated with hyperacusis.

Differential Diagnosis of Facial Weakness

  1. Otitis media
  2. Mastoiditis
  3. temporal bone abscess
  4. Trauma
  5. Iatrogenic surgical injury
  6. Intracranial lesions including tumors, AVMs, infarcts
  7. Nerve tumors
  8. Leukemic invasion of facial nerve, rhabdomyosarcomas
  9. Polio in endemic areas
  10. Hypertension. There have been reports of associated weakness with increased blood pressure that may be controlled when BP controlled or may return intermittently

Course

  1. 85% have complete recovery from weeks to months after onset. 10% have mild residual weakness and about 5% have severe residual facial weakness. Incomplete recovery asociated with total facial involvement. These patients should have electrophysiologic testing and other etiologies should be considered.
  2. There is about a 7% recurrence rate

Treatment

  1. Reassurance.
  2. Use of steroids is controversial with questionable efficacy
  3. Eye care - use of methylcellulose drops to keep eye lubricated and prevent exposure keratopathy.

Reference
1. Gilden  D. Bell's Palsy. NEJM Sept. 23, 2004
2. Sulivan FM et al.  Early Treatment with Prednisolone or Acyclovir in Bell's Palsy.  NEJM Oct 18, 2007
3. Gilden D.H. Tyler K.L. Bell's Palsy- Is Glucocorticoid Treatment Enough? NEJM Oct 18, 2007

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