What is Bell's palsy?
Bell's palsy is the most common form of facial paralysis which causes a weakness of the muscles in the face. Named after Charles Bell, the 19th century Scottish anatomist and surgeon who was the first to describe the condition, it is also known as idiopathic facial nerve palsy.
It occurs when the seventh cranial (nerve controlling your facial muscles) becomes inflamed, swollen or compressed, causing facial paralysis on the affected side. Those suffering from Bell's palsy might find it difficult to close one eye or smile on the affected side.
Bell's palsy can occur at any age; however, it is more common amongst adults and symptoms usually last for a few weeks. It is rare for children to experience Bell's palsy. It is often temporary, with about 85% recovery rate. Because there are other causes of facial nerve palsy, these need to be excluded by investigation.
Bell's palsy causes
Whilst the exact cause of Bell's palsy is unknown, it is suspected to be triggered by exposure to viral infections. These infections can include:
- Herpes Simplex
- Herpes Zoster
Scientists believe that the facial nerve controlling the muscles becomes inflamed in reaction to these infections. When inflamed it can press against the cheekbone and result in damage to the protective covering of the nerve.
When the protective cover of the nerve is damaged, the signals travelling from the brain to the muscles might not be passed on accurately and this can lead to Bell's palsy.
Bell's palsy causes have also been associated with conditions such as:
- The flu
- High blood pressure
- Diabetes Sarcoidosis
- Lyme disease
- Injuries to the face
Bell's palsy causes & risk factors
An equal amount of men and women are affected by Bell's palsy. You're at a higher risk of developing Bell's palsy if:
- You are pregnant
- You are diabetic
- You have the flu
- You have a lung infection
- There's a family history of facial paralysis
Bell's palsy symptoms
Symptoms of Bell's palsy usually develop a couple of weeks after one has had an eye infection, ear infection or cold and can include the following:
- Drooping at the corner of the mouth or eyelid
- Dry mouth
- Dry Eye Syndrome
- Problems eating and drink and a loss of taste
- Facial spasms
- Sensitivity to sound (hyperacusis)
- The inability to make facial expressions
- Pain in the ear
If you experience any of the symptoms above, you should see your GP immediately. Not only is treatment more effective if action is taken right away but these symptoms can also be a sign of more serious conditions, such as a stroke or brain tumour.
How long does Bell's palsy last?
It usually takes around two weeks for one to start to feel better. Full recovery is usually expected within 9 months. Some might find that their symptoms last longer and in cases symptoms can be permanent.
Can stress cause Bell's palsy?
Whilst stress is not a direct cause of Bell's palsy, it can reactivate viruses in the body which can trigger the condition.
Diagnosis of Bell's palsy
There are a range of conditions which can cause facial muscle weakness and thus be mistaken for Bell's palsy. These include strokes, Lyme disease and tumours. There is no specific test for Bell's palsy. However, your doctor will examine your facial muscles by asking you to close your eyes, lift your brow, smile and frown. If the doctor is still unsure about the cause of your symptoms, they also might carry out the following tests:
- Electromyography (EMG)
This test will look at nerve damage and confirm it's severity by measuring the electrical activity of a muscle, taking into consideration how it responds to stimulation and the speed at which electrical impulses along the nerve is conducted.
- Imaging scans
These are carried out in order to check that pressure on the facial nerve is not being caused by a tumour or skull fracture. Scans include Magnetic resonance imaging (MRI) and computerized tomography (CT).
Bell's palsy Treatment
Treatment is not always needed for facial palsy, but abnormal lid closure may lead to dry eye, scarring and risk of infection to the cornea, the window of the eye. It may take several weeks for the facial muscles to regain strength and in most cases symptoms can improve without medical treatment.
Treatment for facial nerve palsy includes the following:
- A 10-day course of steroid tablets, the sooner this is initiated the more effective the treatment
Methods to reduce corneal exposure:
These are used according to the severity of the problem.
- Artificial tear preparations on a regular basis and using surgical tape at night to keep the eye closed may be all that is required
- A moist chamber (sealed plastic eye patch) to prevent evaporation of remaining tear film
- Physical therapy-massaging your facial muscles will prevent paralysed muscles from shrinking and shortening, causing permanent contractures
- Avoid dusty dry environments
To help relieve dry eye as a result of Bell's palsy, take a look at our dry eye treatments.
In severe exposure
- Botulinum toxin injection to the muscle that lifts up the eyelid to enable lid drop.
- Surgical closure of the eyelids (tarsorrhaphy)
- Gold weight insertion into the eyelid using gravity to help it close
Can Bell's palsy affect your eye?
Bell's palsy can cause an extreme case of dry eye known as exposure keratitis. This is due to the fact that your eye on the affected side of the face is unable to blink, thus keeping the cornea constantly exposed to the atmosphere. In addition to this, the lower eyelid may turn outward, a condition known as ectropion.
As well as experiencing a gritty eye, other eye-related symptoms of Bell's palsy include sharp pains and blurred vision. Pain in bright lights (photophobia) may indicate inflammation and infection.
Recommended contacts for Bell's palsy
Those experiencing Bell's palsy should speak to their optician before wearing contact lenses. They may recommend custom made sclera contact lenses, which are dome shaped and larger than normal contact lenses. Rather than sitting on the cornea, like normal contact lenses, they rest on the sclera (white of the eye) instead. However, infection risk may preclude contact lens use.