Bell’s palsy

What is Bell’s palsy?

Bell’s palsy is a condition where the muscles on one side of the face become paralysed because of a problem in the nerve that controls those muscles. This nerve, one of 12 cranial nerves that come from the brain, is called the seventh nerve or facial nerve. The syndrome was described by Sir Charles Bell, a Scottish surgeon, early in the 19th century.

What causes Bell’s palsy?

We are not certain what causes the problem but it appears to be a result of inflammation of the facial nerve due to a viral infection or to an immune reaction. The nerve leaves the brain through a canal in the skull and exits through a small opening in the base of the skull near the ear. The nerve becomes swollen and because of the tight fit in this canal it does not function normally.

In general, the cause of Bell’s palsy is unknown. It may result from problems in the body’s immune system (its system for fighting disease). It may occur if blood flow to the nerve is blocked or constricted, or it may involve inflammation caused by viral infections. Bell’s palsy occurs more frequently in people who have diabetes, in those who have a family history of Bell’s palsy, and in pregnant women.

Very rarely, a tumor (an abnormal growth) can produce symptoms like those of Bell’s palsy. If facial paralysis does not begin to improve after several weeks, your doctor may recommend an MRI test to rule out the rare possibility of a tumor.

What are the symptoms?

The main symptom, which occurs suddenly (maybe overnight), is weakness on one side of the face. The corner of the mouth droops, the eye cannot close properly and every-day actions of the face such as smiling and frowning are not possible and look out of shape. Other possible symptoms include:

• Ear pain just before the problem develops.
• Drooling of saliva.
• Impaired blinking.
• Impaired frowning.
• Difficulty eating.
• Sounds are louder.
• Loss of taste on part of the tongue.

The case can vary from being quite mild and unnoticeable to being quite obvious. You may notice that you cannot smile on one side of your face. Sometimes, patients with Bell’s palsy temporarily cannot close one eyelid completely, which may lead to eye irritation or the feeling of something stuck in the eye.

People with Bell’s palsy may experience facial numbness, although their skin usually retains some sensation. Pain may occur either before the paralysis begins or as it develops. Other symptoms may include:

• decreased tear production;
• blurriness in your vision;
• diminished taste sensations;
• distortions or discomfort in your hearing.

How common is Bell’s palsy?

Each year about one person in 2000 gets Bell’s palsy. It can occur at any age and although it tends to increase with age it is common in young adults. It appears to be associated in some instances with diabetes and high blood pressure. It was common in the past in horsemen and coachmen who were exposed to cold winds on their face for long periods.

What is the outcome?

Although causing concern in the person Bell’s palsy is usually not a serious or permanent problem. Recovery usually begins within three weeks. At least 75% of patients achieve a good recovery and more than 90% recover completely if the problem is mild. The average time for a full recovery is six weeks but some people experience a slow and steady recovery. For those experiencing poor recovery further investigation is usually necessary. There is no good evidence that operations help recovery.