The Facts

Bell's palsy is a sudden facial paralysis that usually strikes all or part of one side of the face. Men or women of any age can suffer Bell's palsy, but statistics suggest that people aged 20 to 35 are at a slightly higher-than-average risk. Overall, your risk of experiencing Bell's palsy is 1 in 5,000 each year, or 1% over an average lifetime. Few people are struck by Bell's palsy more than once in their lives.

Bell's palsy can be a frightening experience, appearing suddenly with symptoms that cause many people to think they're having a stroke. In reality, stroke symptoms are quite different, and Bell's palsy is a comparatively harmless condition that usually clears up without treatment.

Causes

The mystery of Bell's palsy is just now being unravelled. Japanese research has found that 80% of cases can be traced to the common virus called herpes simplex 1, the virus that causes cold sores. The virus infects the seventh cranial (facial) nerve, which helps control the muscles associated with facial expression. As the nerve swells up, it starts to malfunction.

Some people are more prone to Bell's palsy than others. Your risk is higher if you have one of these conditions:

• a common cold or some other upper respiratory ailment
• cold sores
• diabetes
• influenza
• pregnancy
• shingles (possibly)

Herpes zoster, the virus that causes shingles and chickenpox, hides in your nerve roots. Many experts believe this virus is responsible for some cases of Bell's palsy, but this theory is still controversial.

Symptoms and Complications

Bell's palsy usually appears suddenly, often overnight. The primary symptom is weakness and paralysis on one side of the face. You may find that you can't make the same expressions as usual. Typically, you'll be unable to fully close one eye. Other possible symptoms include:

• altered sense of taste
• facial pain, pain in or behind the ear (in fewer than 50% of cases)
• no tears in one eye
• sensitivity to noise on the affected side

There's none of the confusion, language difficulty, or crushing headache that's commonly seen in stroke victims. You may have some trouble talking, but it's purely muscular, whereas stroke victims literally can't find the words they need.

Usually, the symptoms appear at once. Occasionally, they worsen over a few days. Steady, progressive paralysis over several weeks is not a sign of Bell's palsy.

The most serious complication seen in Bell's palsy is permanent mild facial paralysis. This is found in a minority of cases. Overall, about 80% to 90% recover completely over weeks to months, and most of the rest improve.

Incomplete recovery is more likely in people who:

• are over age 55
• feel pain other than ear pain
• have weakness/paralysis on both sides of the face - this occurs in 1% of cases
• show a lack of tears

People who don't recover completely may be left with one or more of the following symptoms:

• abnormal blink
• asymmetrical smile
• buccinator paralysis (food caught in cheek of paralyzed side)
• corneal damage
• drooling of liquids from corner of paralyzed mouth
• dry eye
• excessive perspiration
• frozen muscle in the nostril area
• hyperacusis (perceiving sounds as unusually loud)
• impaired taste
• impaired speech
• synkinesis (involuntary movement associated with a voluntary movement)

Making the Diagnosis

Bell's palsy is diagnosed based on its symptoms and physical signs. There are a huge number of conditions, including head injury, that can cause facial paralysis, but few have the same pattern as Bell's palsy. Additional tests such as CAT scans or MRI scans are usually not necessary.

Treatment and Prevention

Often no medication at all is prescribed, but everyone with Bell's palsy needs special protection for his or her open eye. It will usually remain open for at least a week, and may not be producing tears. Eyedrops, eyepatches, and special lotions at night are used. These almost always prevent long-term damage to the surface of the eye (cornea).

Some specialists give the anti-viral medication acyclovir* if they suspect herpes simplex I. Corticosteroids, such as prednisone, are the commonly prescribed in order to reduce swelling around the nerve. These are usually taken for about 7 to 10 days. There is little evidence, however, to suggest they speed or improve recovery.

In the past, a surgical technique called decompression of the seventh nerve was sometimes used. It's less common now, as many experts believe inflammation and not compression of the nerve is the root of the problem.

There is no known way of preventing Bell's palsy.

*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For more information on brand names, speak with your doctor or pharmacist.