Bell's Palsy

Bell's palsy affects one in 5,000 people, which corresponds to approximately 40,000 people annually in the United States. It does not have a more common occurrence in any particular race or gender, nor is it more severe in any race or gender. People who tend to be more at risk for Bell's palsy are pregnant women in the third trimester, diabetics (who are four times more likely to experience it than healthy people), older people, and immunocompromised people such as those living with HIV or AIDS.

It is the most common cause of temporary facial weakness or paralysis due to the two facial nerves (right and/or left) experiencing damage or other trauma. Typically, the damage occurs to one nerve rather than to both, but symmetric damage may occur. Nevertheless, symmetric, also called bilateral, damage occurs in less than 1 percent of Bell's palsy cases. The facial nerve (cranial nerve VII) innervates the muscles of the face, as well as carrying taste information from the foremost two-thirds of the tongue. It stems from the middle area of the brainstem. If only one facial nerve is affected, a person's entire corresponding one-half of the face may twitch, droop, or exhibit some other form of movement disruption. Most commonly, one side of a person's face will droop. When the person smiles, the typical half-smile is called a “Bell smile.”

The onset of Bell's palsy is usually rapid; typically, people wake up in the morning with an episode of Bell's palsy. Some people may recognize a tingling around the eye or lip prior to the onset of an episode. Most people, however, do not have recurring episodes. Although it is most likely not serious, people with Bell's palsy symptoms should consult a physician. Because of its not unique symptoms, there is no concrete diagnostic tool for Bell's palsy. Rather, a physician must rule out all other possible causes for the paralysis or weakness. Bilateral Bell's palsy is therefore difficult to distinguish from other, much more common causes of bilateral facial paralysis or weakness.

Because many phenomena can disturb the facial nerve, Bell's palsy has a variable etiology. One cause may be inflammation of the nerve due to a viral infection. Possible infections that would affect the facial nerve include viral meningitis or herpes simplex, the cause of a cold sore. The chickenpox and shingles virus (herpes zoster) or Lyme disease may also be responsible for some cases of Bell's palsy; therefore, while Bell's palsy is not transferable, a viral cause might be contagious. Bell's palsy may be an additional symptom of an underlying disorder; for example, a patient with both Crohn's disease and Bell's palsy may in fact have a case of Lyme disease as the cause.

Treatment for Bell's palsy, if any, might include antiviral medications, if a viral cause is suspected. Most people recover completely within weeks to months of the onset. Generally, a person will recover without any medical intervention. Should the person be unable to close the eyes or mouth, thus being at risk for further complications such as a corneal infection, an antiinflammatory medication such as a corticosteroid might be prescribed. Due to the functions of the seventh cranial nerve, people with Bell's palsy may experience intermittent loss of their sense of taste.

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