Chapter 233. Bell's Palsy

Five years ago, a young woman awoke with the inability to move the left side of her face. She was pregnant at that time. On examination it was found that she had absent brow furrowing, weak eye closure, and dropping of her mouth angle (Figure 233-1). She was diagnosed with Bell's palsy and was provided eye lubricants and guidance on keeping her left eye moist. Her physician discussed the available evidence about treatment with steroids. She chose not to take the steroids because of her pregnancy.

Bell's palsy is an idiopathic paralysis of the facial nerve resulting in loss of brow furrowing, weak eye closure, and dropped angle of mouth. Treatment is oral steroids as soon after the onset of symptoms as possible. Most patients have a full recovery within 6 months.

Idiopathic facial paralysis.

• In a Canadian study, incidence was 13.1 to 15.2/100,000 adults.1
• In a study of United States military members, the incidence was 42.77/100,000, with higher incidence in females, blacks, and Hispanics; arid climate and cold months were independent predictors of risk with adjusted relative risk ratios of 1.34 and 1.31, respectively.2
• Women who develop Bell's palsy in pregnancy have a 5-fold increased risk over national average of preeclampsia or gestational hypertension.3
• Seventy percent of cases of acute peripheral facial nerve palsy are idiopathic (Bell's palsy); 30% have known etiologic factors such as trauma, diabetes mellitus, polyneuritis, tumors, or infections such as herpes zoster, leprosy (Figure 233-2) or Borrelia.4
  Figure 233-2Graphic Jump Location

  

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  Bell's palsy secondary to leprosy. The hypopigmented patches on his back are further signs of the leprosy. (Courtesy of Richard P. Usatine, MD.)

• Etiology of Bell's palsy is currently unknown and under debate; the prevailing theory suggests a viral etiology from the herpes family.
• The facial nerve becomes inflamed, resulting in nerve compression.
• Compression of the facial nerve compromises muscles of facial expression, taste fibers to the anterior tongue, pain fibers, and secretory fibers to the salivary and lacrimal glands.
• This is a lower motor neuron lesion; the upper and lower portions of the face are affected (...