Bell's palsy
Introduction
Bell's palsy is a condition that causes temporary weakness or paralysis to the muscles in one side of the face. It is the most common cause of facial paralysis.
The symptoms of Bell’s palsy vary from person to person. The weakness on one side of the face can be described as either:
- partial palsy, which is mild muscle weakness
- complete palsy, which is no movement at all (paralysis)
In rare cases, complete or partial palsy can affect both sides of a person’s face.
The muscle weakness or paralysis of Bell’s palsy can also affect the eyelid, making it difficult to close or open the eye.
The exact cause of Bell's palsy is unknown, although many researchers believe that the herpes virus is responsible. See Bell’s palsy - causes for more information.
How common is Bell's palsy?
Bell's palsy is a rare condition that affects about 1 person in 5,000. It tends to affect those aged between 15 and 45, and both men and women are affected equally.
Bell's palsy is more common in pregnant women and those with diabetes and HIV, for reasons that are not entirely clear.
Outlook
Around 7 out of 10 people with Bell's palsy make a complete recovery.
Most people with Bell’s palsy notice an improvement in their symptoms after two to three weeks (with or without treatment). However, a complete recovery can take between three and six months. The recovery time varies from person to person and will depend on the amount of nerve damage.
Around 3 in 10 people with Bell’s palsy will continue to experience weakness in their facial muscles, and 2 out of 10 will be left with a more serious long-term problem. For example, their face may look different from shortening of the facial muscles. See Bell’s palsy - complications for more information.
Steroid medications are sometimes used to speed up the recovery process. It is important to take good care of the affected eye during recovery. See Bell’s palsy - treatment for more information.
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Symptoms
The symptoms of Bell’s palsy develop quickly, often overnight, or in a couple of hours.
Symptoms of Bell's palsy include:
- weakness, or paralysis, in one side of your face, which may make it difficult to close your eyelid, and cause the side of your mouth to droop,
- irritation in the affected eye, due to it being constantly exposed,
- pain underneath your ear, on the affected side of your face,
- an altered sense of taste,
- an increased sensitivity to sound in the affected ear, and
- drooling from your mouth on the affected side of your face.
In most cases of Bell's palsy, the symptoms will begin to improve within three weeks.
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Causes
The facial nerve
The majority of the muscles in your face are controlled by a single nerve, known as the facial nerve.
The facial nerve passes through a narrow gap of bone on its way from your brain to your face. Bell's palsy is thought to occur because a virus, usually the herpes virus, causes the nerve to become inflamed. If the nerve is inflamed, it will press against the cheekbone.
If the facial nerve is compressed, it is likely to become damaged, interfering with the signals that your brain is sending to the muscles in your face. The interference results in the weakness, or paralysis, that is characteristic of cases of Bell's palsy.
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Diagnosis
You should see your GP within 72 hours of developing symptoms of Bell's palsy because studies have shown that treatment is most effective if it is started within this time period.
Diagnosis by exclusion
Bell's palsy is diagnosed using a process that is known as diagnosis by exclusion. Your GP will look for any evidence that your symptoms may be caused by another health condition, such as Lyme disease (a bacterial infection caused by ticks), or tumor.
Diagnosis by exclusion involves carrying out a detailed physical examination of your head, ears and neck. Your GP will also check the muscles in your face in order to confirm whether only the facial nerve is affected.
If your GP cannot find any evidence to suggest other symptoms, such as the characteristic rash that is left by ticks, in Lyme disease, or a change in your facial structure that could suggest a tumor, a diagnosis of Bell's palsy can usually be made.
Further testing
If your GP is unsure whether Bell's palsy is the cause, they may refer you to an ear, nose and throat (ENT) specialist for further testing. Possible further tests are described below.
Electromyography (EMG)
Electromyography (EMG) is where electrodes are placed on your face, and a machine is used to measure the electrical activity in your nerves. An EMG can provide more information about the location and extent of any nerve damage.
Imaging scans
Imaging scans, such as a magnetic resonance imaging (MRI) scan, that uses radio waves and a strong magnetic field to produce a detailed image of the inside of your body, or a computerised tomography (CT) scan, may be able to detect other causes of your symptoms, such as an infection, or tumour.
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Treatment
Medication
In recent years, there has been some disagreement among healthcare professionals about whether Bell's palsy can be most effectively treated using steroids, antiviral medications or a combination of both (see below).
However, recent evidence suggests that the most effective treatment for Bell’s palsy is a steroid medication called prednisolone, which should be given within 72 hours of the symptoms starting.
Prednisolone
Prednisolone works by helping to reduce inflammation (swelling), which should also help to speed up your recovery. Most people with Bell's palsy are advised to take prednisolone tablets twice a day, for a period of 10 days.
Possible side effects of prednisolone include:
- nausea (feeling sick)
- headache
- increased sweating
- indigestion
- abdominal (tummy) pain
- increased appetite
- difficulty sleeping
- oral thrush (a fungal infection of the mouth)
- tiredness
- dizziness
These side effects should improve within a few days as your body begins to get used to the medication. Do not drive or operate heavy machinery if you find that your medication is making you dizzy or sleepy.
Some people also experience mood changes, such as anxiety or depression, after taking steroids for a short period of time. You should visit your GP immediately if you experience mood changes or if you have other side effects that are particularly troublesome.
See the Health page about Corticosteroids - side effects for more information.
If you are pregnant or breastfeeding you should speak to your GP before taking prednisolone.
You should also consult your GP if you develop symptoms of oral thrush, which can usually be treated with antifungal medication. The main symptom of oral thrush are white spots that appear on the inside of your mouth and tongue.
See the Health topic about Oral thrush for more information.
Eye care
Tears play an important part in helping to protect your eyes by keeping them free of dirt and bacteria which could cause eye infections.
If you have Bell’s palsy, you might find it difficult to close your eye, which can cause your tears to evaporate, leaving your eye vulnerable to infection. It is therefore, very important to keep your eye lubricated.
Your GP may prescribe eye drops that contain 'artificial tears' for use during the day, plus an ointment which you should use at night. If you are unable to shut your eye during the night time, your GP will give you some surgical tape to close your eye.
If your eye symptoms worsen, you should visit your local accident and emergency (A&E) department or the ophthalmology department of your local hospital for assessment.
Botulinum toxin injections
Botulinum toxin (Botox) injections can be used to treat either the affected or the unaffected side of the face in people with long-term Bell's palsy.
Botox may be injected into the affected side of the face to relax any facial muscles that have become tight or to reduce any unwanted muscle movements.
If the muscles in the unaffected side have become overactive or dominant, Botox may be injected into this side of the face to reduce muscle activity and balance the movement of the face.
Some of the long-term complications of Bell’s palsy can also be treated using Botox injections. These include the following.
- tears when eating, known as ‘crocodile tears’
- eye-mouth synkinesias: where the facial nerve grows back in a different way, which can lead to a winking eye when eating, smiling or laughing
See Bell’s palsy - complications for more information.
The Botox injections can help ease any discomfort that is experienced while eating and can also help to improve the overall appearance of the face. The injections need to be repeated every four months.
Further treatment
Most people who have Bell's palsy will make a full recovery within nine months. However, if you have not recovered by this time, you may have experienced more extensive nerve damage and further treatment may be required.
Physiotherapy may be recommended. Your physiotherapist will teach you a series of facial exercises that will strengthen the muscles in your face to improve their co-ordination and range of movement.
Physiotherapy has been successful in a number of Bell's palsy cases, although it may not be suitable or effective for everyone.
Another possible treatment option is plastic surgery. The surgeon may not be able to restore nerve function, but may be able to improve the appearance and symmetry of your face.
Research has suggested that facial exercises, relaxation techniques and acupuncture can help speed up the recovery of Bell’s palsy and restore facial nerve function.
Steroids and antiviral medications
There has been some disagreement about the use of a combination of antiviral medications and steroids, or the use of steroids alone, for treating Bell’s palsy.
It is thought that steroids are effective at reducing inflammation (swelling) and that antiviral medications can help to fight the herpes virus that may have caused the condition.
However, there is some evidence to suggest that steroids alone are effective in treating Bell’s palsy. There is also evidence to suggest that antiviral medication is only effective if used in combination with steroids.
The treatment that you receive for Bell’s palsy will depend on your circumstances and will take into account the suspected cause of your condition.
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Complications
About 2 in 10 people experience long-term problems resulting from Bell’s palsy, which may include any of the following:
- A contracture - where your facial muscles are permanently tense, which can lead to facial disfigurement such as the eye becoming smaller, the cheek becoming more bulky or the line between the nose and the mouth becoming deeper.
- Loss or reduced sense of taste - this can happen if any damaged nerves do not repair properly.
- Speech problems - this can occur as a result of damage to the facial muscles.
- Eye-mouth synkinesias - this happens as a result of the nerve in your face growing back in a different way. It is possible to have a winking eye when eating, laughing or smiling. Sometimes it can become so severe that the eye can close completely during meals.
- Eye drying and corneal ulceration - corneal ulceration can occur when the eyelid fails to close completely and the protective tear film becomes less effective. It can also occur as a result of reduced tear production, which can lead to infection and cause blindness.
Long-term complications of Bell’s palsy are more likely to happen if:
- you have been affected by a complete palsy - no movement at all (paralysis) on one side of your face
- you are over 60 years of age
- you had severe pain when you first experienced symptoms
- you have high blood pressure
- you have diabetes
- you are pregnant
- your facial nerve is badly damaged
- you have not started to recover after six weeks
Ramsay Hunt syndrome
If you have Bell’s palsy that was caused by the varicella-zoster virus, there is a slim possibility that you could develop a more serious condition called Ramsay Hunt syndrome. However, the condition is rare, with less than 2 in 100 people with Bell’s palsy being affected.
Ramsay Hunt syndrome can cause blisters to appear on your tongue and the inside of your ears. It can usually be treated with steroids and antiviral medication.
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