Bell's Palsy Health Article

Definition

Bell's palsy describes an unexplained weakness or paralysis of the muscles on one side of the face. Afflicted individuals may be unable to close the eye on the affected side of the face, and may also experience tearing, drooling, and hypersensitive hearing. The onset can be quite sudden, sometimes occurring overnight. Although Bell's palsy is unsettling and inconvenient, it is typically not indicative of a serious health problem. The weakness and paralysis resolve completely in the majority of cases.

Description

Bell's palsy has been described as a diagnosis of exclusion because several other disorders present similar symptoms. Facial palsies have been linked to conditions such as Lyme disease, ear infection, meningitis, syphilis, German measles (rubella), mumps, chickenpox (varicella), and infection with Epstein-Barr virus (e.g., infectious mononucleosis). True Bell's palsy is an idiopathic facial palsy, meaning the root cause cannot be identified. Although Bell's palsy is not life-threatening, it can present symptoms similar to truly serious conditions, such as a stroke, ruptured aneurysm, or tumors.

Every year, approximately 40,000-65,000 Americans are stricken with Bell's palsy. Worldwide, there is an annual incidence of 20-30 cases per 100,000 individuals. An individual can be affected at any age, but young and middle-aged adults are the most likely to be affected. It is unusual to see Bell's palsy in people less than 10 years old. Bell's palsy can affect either side of the face, and neither gender seems to be at a greater risk. Pregnant women and individuals with diabetes, influenza, a cold, or an upper respiratory infection seem to be at a greater risk. Although it cannot be considered a serious condition from a health standpoint, it can cause extreme stress, embarrassment, and inconvenience for those affected.

In the large majority of cases (80-85%), the facial weakness or paralysis is temporary. However, individuals who experience complete paralysis seem to have a poorer recovery rate with only 60% returning to normal. Approximately 4-6% of all Bell's palsy cases result in permanent facial deformity, and another 10-15% experience permanent problems with spasms, twitching, or contracted muscles. Between 2% and 7.3% of individuals who have experienced Bell's palsy will have a recurrence. On average, the first recurrence happens 9.8 years after the first episode; the second, 6.7 years later. One recurrence is very infrequent, and a second is extremely rare.

Causes and symptoms

The symptoms of Bell's palsy arise from an inflammation or swelling of the seventh cranial nerve, otherwise called the facial nerve. Both sides of the face have a facial nerve which controls the muscles on that side of the face. The course of the facial nerve passes through a bony canal in the skull. When the nerve becomes swollen, it is compressed since the canal does not allow for any expansion. As further swelling increases the compression, nerve signal conduction is impeded or even prevented. The interference with the nerve signals is seen in the loss of muscle control and tone.

Why the facial nerve becomes inflamed in Bell's palsy is a matter of some debate, and medical researchers and doctors are not in complete agreement. The best-supported evidence implicates the herpes simplex virus (HSV), which is responsible for cold sores and fever

blisters. HSV infection has been discovered in up to 70% of Bell's palsy cases. Most people harbor this virus, although they may not exhibit symptoms.

The major symptom of Bell's palsy is one-sided facial weakness or paralysis. Muscle control is either inadequate or completely missing. There may also be involuntary facial movements, such as twitches, that accompany certain facial expressions. Afflicted individuals frequently have difficulty shutting the affected eye and may not be able to close it at all.