The nerve splits into many branches that supply the small muscles of the face that you use to smile, frown, etc. It also supplies the muscles that you use to close your eyelids.
The facial nerve also takes taste sensations from your tongue to your brain.
Who gets Bell's palsy?
Anyone can get Bells palsy, and it affects both men and women equally. It most commonly occurs between the ages of 10 and 40. Bell's palsy is the most common cause of a sudden facial weakness. About 1 in 70 people have a Bell's palsy at some stage in their life.
What causes Bell's palsy?
The exact cause is not known. It is thought that inflammation develops around the facial nerve as it passes through the skull from the brain. The inflammation may compress (squash) the nerve as it passes through the skull. The nerve then partly, or fully stops working until the inflammation goes. If the nerve stops working, the muscles that the nerve supplies also stop working.
The cause of the inflammation is not known, but it is probably due to a viral infection. There is some evidence that the cold sore virus (herpes simplex virus) causes most cases of Bell's palsy.
(Note: The term Bell's palsy is given for a facial palsy 'of unknown cause'. Rarely, facial palsy is caused by a head injury, sarcoidosis, Lyme disease, and other rare problems. These are not called Bell's palsy as there is a known underlying cause, and you would normally have other symptoms too. Also, some people who have a stroke develop facial weakness. This is different to the facial weakness of Bell's palsy.)
What are the symptoms of Bell's palsy?
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Weakness of the face which is usually one sided. The weakness usually develops quickly, over a few hours or so. You may first notice the weakness after getting up in the morning, and so it may appear quite dramatic. It may gradually become worse over several days. The effects of the weakness vary, depending on whether the nerve is partially or fully affected. These include the following.
- Your face may droop to one side. When you smile, only half of your face may move.
- Chewing food on the affected side may be a problem. Food may get trapped between your gum and cheek. Drinks and saliva may escape from the side of your mouth.
- You may not be able to close an eye fully. This may result in a watery or dry eye.
- You may not be able to wrinkle your forehead, whistle, or blow out your cheek.
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Most cases are painless, but an ache near the ear may occur for a few days.
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Loud sounds may be uncomfortable and normal noises may sound louder than usual. This is because a tiny muscle in the ear may stop working.
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Your may lose the sense of taste on the side of the tongue that is affected.
Does Bell's palsy affect the brain or other parts of the body?
No. Bells palsy is a local problem confined to the facial nerve and facial muscles. If you have other symptoms, such as weakness or numbness in other parts of your body, there will be another cause and you should tell your doctor.
How does Bell's palsy progress?
Without treatment, full recovery occurs in about 8 in 10 cases. The function of the nerve gradually returns to normal. Symptoms usually start to improve after about 2-3 weeks, and have usually gone within two months. In some cases, it can take up to twelve months to fully recover.
In about 2 in 10 cases, symptoms do not completely go. Some weakness may remain for good. However, it is often a slight weakness of part of the face. It is rare to have no improvement at all.
What is the treatment for Bell's palsy?
Steroid tablets may be prescribed for one or two weeks. Steroids help to reduce inflammation. But, steroid treatment for Bell's palsy is controversial. As mentioned above, you are likely to recover fully without any treatment, and some studies suggest that steroids make no difference to the outcome. However, some doctors believe that a course of steroids may help to increase your chance of full recovery even more. If steroids are advised, you should start them as soon as possible after the onset of symptoms.
Eye protection. If you cannot close your eyelids fully, the front of your eye is at risk of becoming damaged. Your doctor may advise one or more of the following until the eyelids recover.
- Wear an eye pad or goggles to protect the eye.
- Eye drops may help to lubricate the eye.
- Eye ointment may be better at bedtime to lubricate the eye overnight.
- An option is to tape the upper and lower lid together.
Surgery to the face may be an option for the small number of cases where the facial weakness does not recover, and remains unsightly.
Will it happen again?
In most cases, a Bell's palsy is a 'one-off'. About 1 in 10 people who have a Bell's palsy have a further episode sometime in the future, often several years afterwards.
©EMIS and PIP 2004 Updated: May 2002 CHIQ Accredited
