Bell's palsy is a common condition in which inflammation or damage to the facial nerve causes muscle paralysis on one side of the face. The disorder tends to come on suddenly, causing half of the face to droop and feel numb to the touch. Most episodes are relatively short-lived, and symptoms may go away on their own within two to three weeks. Doctors usually suggest seeking medical treatment, however, to ease symptoms and promote faster recovery time.
It is often difficult to identify an underlying cause of nerve inflammation, and many cases of Bell's palsy are deemed idiopathic. There is evidence suggesting that certain types of viruses, including herpes simplex and Ebstein-Barr, can attack and damage the facial nerve. Diabetes is also known to affect blood vessels and nerves in the face, which can increase the likelihood of developing Bell's palsy. In addition, some people appear to be genetically predisposed to nerve problems.
Bell's palsy symptoms usually come about quickly, sometimes within minutes. Either the left or right side of the face starts to feel weak and tingly, and there may be dull pain in the jaw region. Total paralysis can occur in a few hours or days, which makes it impossible to open or close the affected eye and half of the mouth. Other symptoms may include a progressively worsening headache, sound sensitivity, drooling, and increased tear production.
A person who believes he or she may be experiencing Bell's palsy symptoms should seek medical care right away. Several other more serious conditions can also cause facial paralysis, including strokes and cancerous tumors. A doctor can rule out other causes by taking magnetic resonance imaging scans and electroencephalographs to look for physical abnormalities or changes in brain activity. Blood tests may be performed to confirm the presence of a particular virus. After making a diagnosis, the physician can explain different treatment options.
The most common cause of Bell's palsy appears to be the herpes simplex virus, which also causes cold sores and genital herpes. Other viruses that have been linked to Bell's palsy include:
The virus that causes chickenpox and shingles (herpes zoster)
The virus that causes mononucleosis (Epstein-Barr)
Another virus in the same family (cytomegalovirus)
With Bell's palsy, the nerve that controls your facial muscles, which passes through a narrow corridor of bone on its way to your face, becomes inflamed and swollen — usually from a viral infection. Besides facial muscles, the nerve affects tears, saliva, taste and a small bone in the middle of your ear.
The onset of paralysis is sudden with Bell's palsy and Ramsey Hunt syndrome, although symptoms can worsen during the early days. Bell's palsy symptoms typically peak within a few days, although it can take as long as 2 weeks. Ramsey Hunt syndrome symptoms will peak within 3 weeks. If paralysis develops slowly, tests for other causes of the palsy must be done. Patients with recurrences, particularly if within close time frames, should also be re-evaluated as a precautionary measure.
There are many physical symptoms associated with facial paralysis, but the effects will differ between individuals. They can vary in accordance with the degree of nerve damage, and the location of the damage.
Muscle weakness or paralysis
Forehead wrinkles disappear
Overall droopy appearance
Impossible or difficult to blink
Nose runs
Nose is constantly stuffed
Difficulty speaking
Difficulty eating and drinking
Sensitivity to sound (hyperacusis)
Excess or reduced salivation
Facial swelling
Diminished or distorted taste
Pain in or near the ear
Drooling
Eye closure difficult or impossible
Lack of tears
Excessive tearing
Brow droop
Tears fail to coat cornea
Lower eyelid droop
Sensitivity to light
Eye appears smaller
Blink remains incomplete or infrequent
Tearing abnormalities
Asymmetrical smile
Mouth pulls up and outward
Sinus problems
Nose runs during physical exertion
Post paralytic hemifacial spasm
Hypertonic muscles
Co-contracting muscles
Synkinesis (oral/ocular well known, but can affect any muscle group)
Sweating while eating or during physical exertion
Muscles become more flaccid when tired, or during minor illness
Muscles stiffen when exposed to cold, when tired, or during illness
Although the damage that causes the paralysis is specific to the 7th nerve, other nerves may be temporarily irritated. For example, temporary facial numbness or pain can result when CN-V is irritated.
Recovery is not consistent among patients. For some people the mouth may move before the ability to blink returns; in others it will be eyelids first and mouth last. Twitching may precede movement, but it doesn't always. Pain in areas starting to "wake up" may occur, or may not. The sense of taste can be odd as the sensation returns, or the sense of taste may return without any awareness of the change. Recovery can be gradual, rapid, or hit occasional plateaus. Et cetera.
Residuals may be due to one, or a combination of several factors. Initial trauma to the nerve can be minor and temporary, or significant and long lasting. When the damage is minor, recovery is likely to be essentially complete, and rapid. With more extensive damage, other factors begin to effect recovery.
In longer recoveries, other cranial nerves may try to take over for the 7th nerve, growing into passageways formerly occupied by the 7th nerve. Also, the 7th nerve can regenerate incorrectly, taking some different paths than it had followed before Bells palsy. The result is "crossed wiring" and synkinesis, which is further described in the next section.
After paralysis facial muscles have a tendency to become hypertonic. This means they tend to be overactive, contracting when they should be at rest. Typical signs are a squinty eye, the mouth pulling up, a sore or swollen cheek, and deepened creases. Unlike skeletal muscles, facial muscles lack spindles. Muscle spindles sense when a muscle is in a contracted state, and nerves can send the appropriate signal to the muscle telling it to relax. Without these spindles, there is no awareness of the contraction, and the muscles remain in a state of tension. A muscle that can not fully relax also can not fully contract, so the range of motion becomes limited.
Learned misuse and disuse of the muscles also can effect both appearance and mobility. While the muscles are paralysed, it's natural to try to eat, drink and speak, etc., as well as you can. New habits may be learned while you're compensating for the nonworking muscles. You may inadvertently call on inappropriate muscles to join forces and work together to accomplish movements that aren't happening on their own (learned misuse). Or you may become accustomed to compensating without using the lazy muscles (learned disuse). The effects of both may remain after nerve function returns. Both can also effect the "good" side, which may have learned unnatural patterns while its muscles were assisting the nonworking muscles.
Physical therapy can minimize asymmetrical appearance and improve mobility, even when therapy is started years after the initial paralysis.
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.
However, recent evidence suggests that a steroid called prednisolone is the most effective treatment for Bell’s palsy, and that it should be given within 72 hours of the symptoms starting.
Prednisolone works by helping to reduce inflammation (swelling), which should also help to speed up your recovery. In most cases, people with Bell's palsy are advised to take prednisolone tablets twice a day for a period of 10 days.
Tears play an important role in protecting your eyes and 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 and leave your eye vulnerable to infection. Therefore, it is very important to keep your eye lubricated.
Your GP may prescribe eye drops that contain 'artificial tears' for daytime use, plus an ointment that you should use at night. If you are unable to shut your eye at night time, your GP will give you some surgical tape to close your eye.
If your eye symptoms get worse, you should visit your local accident and emergency (A&E) department or the ophthalmology department of your local hospital for assessment.
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. The injections need to be repeated every four months.
Most people with 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 needed.
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.
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.