Neurology

Bell's Palsy

Bellspalsy_0.JPG
A person attempting to show his teeth and raise his eyebrows with Bell's palsy on his right side. Note how the forehead is not spared.
https://en.wikipedia.org/wiki/Bell%27s_palsy

Introduction

Bell's Palsy , defined as unilateral facial weakness, is a relatively common pediatric problem affecting children from infancy to adolescence (Illustration Shown on the Right). 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

435px-Cranial_nerve_VII.svg__0.png
Facial nerve: the facial nerve's nuclei are in the brainstem (represented in the diagram by "θ"). Orange: nerves coming from the left hemisphere of the brain, yellow: nerves coming from the right hemisphere. Note that the forehead muscles receive innervation from both hemispheres (yellow and orange). 
https://en.wikipedia.org/wiki/Bell%27s_palsy

Idiopathic, congenital, traumatic, and neoplastic causes can all acount for facial nerve palsy. Nearly half of these qualify as Bell's palsy and are 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

Physical manifestations may go unnoticed by parents, and may have sudden onset (within a period of hours).

  1. Weakness of upper and lower face (forehead muscle sparing is suggestive of upper motor neuron lesion due to bilateral innervation)
  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
  9. Prodrome of ear pain and dysacusis may be present

 

 

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.
  4. Lyme serologies suggested for all children with possible exposure in Lyme endemic areas Spring-Fall

 

References

  1. Gilden  D. Bell's Palsy. NEJM Sept. 23, 2004
  2. Sulivan F.M. 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
  4. Arnold D.H. Spiro D.M. Visual Diagnosis: A Child Who Has Facial Palsy and Rash. Peds in Review Dec 1, 2007
  5. Manzouri B. et al. Bell's Palsy in a 3 Month Old Infant. Journal of Ped Opthalmology and Strabismus. Feb 15, 2011