Bell's palsy
Bell's palsy was named after Sir Charles Bell, a 19th century doctor who first described the condition and linked it to a problem with the facial nerve.
What is Bell's palsy?
Bell's palsy is paralysis or weakness of the facial muscles on one side only. It comes on suddenly and has no obvious cause. It is the most common cause of paralysis affecting the face.
The condition is fairly common. In the UK, about one in 60 people will be affected at some point in their lifetime. It can affect all age groups, including children, but seems to be most common between the ages of 15 and 45. Men and women are equally affected, although pregnancy increases the risk threefold.
Causes
The exact causes of Bell's palsy are unknown. However, it is thought that viral infection of the facial nerve is the most likely cause. Herpes simplex - the virus responsible for cold sores - may lie inactive (dormant) at the root of the facial nerve, causing swelling when it reactivates ("wakes up"). Other viral illnesses such as herpes zoster (the virus responsible for chickenpox and shingles) may also trigger Bell's palsy. Having diabetes seems to increase the risk.
Symptoms
The symptoms of Bell's palsy are likely to come on very quickly - often in a matter of hours or overnight. The main symptom is likely to be paralysis or weakness on one side of the face, along with a sagging eyebrow and difficulty closing the eye. Mild earache or pain behind the ear is sometimes the first sign of Bell's palsy. There are several other possible symptoms including:
a sagging mouth
dribbling of saliva and drinks
difficulty in speaking
alteration or loss of taste at the front of the tongue
dryness or watering of the affected eye
a turned-out lower eyelid
unusually sharp hearing on the affected side
About four out of five people with Bell's palsy recover completely (or report significant improvements) within three weeks. The rest usually start to see some improvement within three to six months, when the nerves have had a chance to re-grow.
Occasionally, new nerve fibres that grow back after Bell's palsy connect to the wrong facial muscle. This can have lasting effects, and may cause one or several of the following.
Diagnosis
Your doctor will usually be able to identify Bell's palsy by examining your face and listening to a description of your symptoms.
There are tests that you can have to check for other diseases that can cause paralysis. For example Lyme disease, spread by ticks, can cause muscle weakness similar to Bell's palsy. So blood tests might be done to check for Lyme disease. An MRI scan may be done to examine the brain for any signs of a stroke or a brain tumour, as these can also cause facial paralysis. For more information, please see the separate Bupa health factsheet, MRI scan.
Other causes of facial paralysis include:
pressure on the facial nerve (eg caused by a tumour)
infections (eg Lyme disease)
sarcoidosis (a condition of the immune system)
disorders which affect the immune system, such as HIV/AIDS
facial wounds
The cause of Bell's palsy is idiopathic, which means that its cause is unknown. So, if any of the conditions above are shown to be the cause of your facial paralysis, you do not have Bell's palsy.
Treatment
For most people, Bell's palsy gets better by itself without any treatment at all. Many experts recommend starting a course of steroids within a week of the start of symptoms to increase the chance of a good recovery.
There is also a theory that anti-viral drugs (such as aciclovir), taken with the steroids, can improve your recovery even more. The theory is that the steroids reduce the swelling of the nerve, while the anti-viral drugs stop the herpes viruses that may have caused the swelling.
However, while many doctors support the use of steroids and anti-viral drugs, there is only limited evidence to show that these treatments are effective, and more research needs to be done.
Physiotherapy, acupuncture, facial exercises and massage may be used, but there is little scientific evidence to prove that these treatments work.
Bell's palsy may make it hard to close your eyelid. These safeguards can help stop the surface of your eyeball drying out.
Regularly close the eye by pulling the upper lid down with your finger.
Wear protective glasses or an eye patch.
Tape the eye closed before you go to sleep.
Use artificial tears (eye drops) to keep the eye moist - ask a pharmacist for advice.
In some cases, a small dose of botulinum toxin can be injected into the upper eyelid. This causes it to droop temporarily, protecting the eye. Botulinum toxin may also be used to reduce facial spasms.
For the small number of people who have long-term paralysis from Bell's palsy, there are several treatment options.
A surgical technique called tarsorrhaphy, which narrows the space between the upper and lower eyelids, may improve eye closure.
A weight may be fitted into the upper eyelid to help keep the eyelid closed.
Surgery can be done to relieve pressure on the facial nerve, although this is rarely recommended.
Plastic surgery may improve permanent facial drooping.
Further information
Bell's Palsy Association
http://www.bellspalsy.org.uk/
