Bell’s palsy is a temporary paralysis or weakness that usually occurs on one side of the face when there is damage to facial nerves. The condition may also be referred to as acute idiopathic facial palsy or Bell’s palsy syndrome.

Bell’s palsy is the most common cause of facial paralysis. The paralytic symptoms may begin suddenly and peak within 48 hours. Most patients improve gradually and their symptoms diminish or disappear within two weeks. Some may experience the effects for six months to a year. A few people may experience permanent facial muscle shrinkage and a distorted appearance, such as an asymmetric smile that curves up on one side and down on the other.

The affected areas may start at the forehead and stretch down to the chin and over to the ear, usually on one side of the face. This can cause the mouth and affected eyelid to droop and sag. The ability to blink may be hindered to the point that the eye dries out from lack of lubrication. Dryness makes the eyes more susceptible to injury or infection. Debris can more easily fly into the eyes, making them more vulnerable to injury. Drooling and slurred speech can also occur. Some people may experience hearing loss or hypersensitivity to sound on one side.

The causes of Bell’s palsy are not well understood. Viral infections, such as the herpes viruses that cause cold sores and shingles may be involved. The viruses may cause inflammation and pressure along the facial nerve, contributing to the paralysis. For some people, the facial palsy may be preceded by influenza or respiratory illness. Other causes may include facial trauma, such as from an automobile accident or sports injury.

Treatment for Bell’s palsy depends on the cause of the facial nerve damage. Antiviral medications and corticosteroids may be prescribed to fight infection and inflammation and pain relievers may be taken for jaw, ear or mouth pain that may accompany the paralysis. However, even after a patient fully recovers, there can be a relapse. One in five patients has recurrences of facial palsy.

Bell’s palsy or facial palsy occurs when the nerve controlling facial muscles becomes compressed, inflamed or swollen. This leads to facial paralysis, or palsy, and weakness in the muscles controlling facial expressions and movement. The paralysis or weakness often starts suddenly and affects only one side of the face, which may give the face a distorted appearance.

Most facial expressions and movements are controlled by the seventh cranial nerve, or facial nerve. The nerve and its branches carry messages from the brain to the face and run through the skull, under each ear and to the muscles on each side of the face. The facial nerve controls such functions as eye blinking and winking, eyebrow arching, smiling, frowning and grimacing. These nerves also direct the muscles responsible for taste sensation in the tongue, the tear glands, the saliva glands and the small bone of the middle ear (the stapes).

The facial nerve travels through a passageway in the bone called the fallopian canal. Infections such as cold sores, influenza or herpes viral infections like shingles may cause swelling and inflammation that create pressure within this canal. Bell’s palsy may be a reaction of the nerve to these infections. The pressure and inflammation in the canal cut off blood and oxygen to the nerve cells. It may damage the myelin, a fatty substance that coats the nerve fibers and helps conduct nerve signals. In mild cases, nerve damage is limited to the outer myelin sheath. Patients with minor myelin damage can recover quickly. Patients with more severe cases of Bell’s palsy experience damage to the nerve cells and recovery is more gradual.

Viral infections associated with Bell’s palsy may occur shortly before the paralysis or in some cases, months or years before. For example, the herpes simplex viruses are extremely common, causing cold sores and shingles. After an initial infection, the virus remains dormant in the central nervous system and can be reactivated at any time. The virus then reproduces and travels along the nerves, triggering immune system responses that lead to inflammation, myelin destruction and paralysis.

Bell’s palsy can also occur after facial trauma or skull fractures (such as in automobile accidents or sports injuries). The same paralysis and swelling can occur if the fallopian canal is crushed or damaged and pressure builds on the nerve fibers.

The facial paralysis experienced by the majority of Bell’s palsy patients is usually temporary. After the source of the nerve damage is removed (e.g., the virus goes into remission or is treated, the inflammation subsides), the nerves are no longer compressed or pinched and normal muscle function can resume. In addition, damaged nerve cells and fibers may regenerate over time. Muscle function may return during this process. However, severe facial nerve degeneration that occurs for longer than two to three weeks may be irreversible. Bell’s palsy also may recur for some patients.

Bell’s palsy affects about 40,000 people a year in the United States, according to the National Institute of Neurological Disorders and Stroke (NINDS). It can occur at any age, but most commonly affects people between the ages of 15 and 60.

The exact causes of Bell’s palsy have not been identified. Many researchers believe Bell’s palsy may be triggered by viral infections, including the common cold sore virus (herpes simplex) and the virus responsible for shingles (herpes zoster). A causal relationship is difficult to determine because the viruses are so common. Most patients with Bell’s palsy have been exposed to these viruses, but so have most people who do not develop Bell’s palsy. Other viral infections associated with the disorder may include cytomegalovirus, Epstein Barr virus, adenoviruses, rubella virus, mumps, influenza B virus and coxsackievirus.

In addition, some conditions may place greater pressure on the facial cranial nerve and increase the risk of Bell’s palsy. These conditions include:

• Chronic middle ear infections
  
  
• Neurosarcoidosis
  
  
• Head injuries and facial traumas
  
  
• Benign tumors (acoustic neuromasacoustic neuromas) compressing the facial nerve
  
  
• Other progressive nerve diseases (e.g., multiple sclerosis)
  

  

Bell’s palsy may also be related to autoimmune disorders, where the immune system attacks regular body tissues as if they were invading organisms. It may lead to tissue inflammation around the facial nerve. Problems with blood circulation in the facial area may also contribute to Bell’s palsy.  

Symptoms of Bell’s palsy can begin suddenly, escalate and peak within about 48 hours. These symptoms usually go away within two to three weeks, especially for people with mild cases. People can experience mild weakness to severe total paralysis (or numbness) of their facial muscles, usually on one side of the face.

The condition often starts without warning overnight and the person awakens to a tingling or numb sensation in the face and a distorted facial expression. Others may experience jaw pain or pain behind the ear. They may also have ringing in one or both ears (tinnitus) and headaches. Some people report pain behind the ear a few days before the onset of the palsy.

Bell’s palsy usually affects one side of the face. Paralysis that affects both sides of the face may be related to other conditions, including Guillain-Barre syndrome and meningitis.

Other symptoms associated with Bell’s palsy include:

• Facial twitching
• Dizziness
• Drooping eyelids (ptosis)
• Changes in salivation and tearing (increased or decreased)
• Sagging lips or drooping mouth
• Slurred speech
• Heightened sensitivity to sound on the affected side
• Impaired taste sensation
• Difficulty eating or drinking

Patients experiencing symptoms similar to Bell’s palsy (facial paralysis and weakness) should seek medical attention. A physician will first take the patient’s medical history and conduct a complete physical examination.

Bell’s palsy is considered a diagnosis of exclusion, which means that other potential causes of the paralysis must be ruled out. These may include stroke, transient ischemic attack, Lyme disease or multiple sclerosis. When other causes for the symptoms cannot be determined, Bell’s palsy is often identified. Diagnosis depends almost exclusively on the physical examination. The physician will examine the upper and lower facial muscles and determine the extent of weakness. Patients may be asked to open and close their eyes tightly, lift and lower their eyebrows, wink, whistle and smile or show their teeth. Saliva and tear production may be noted, and taste and balance tests may also be performed.

In addition, the following diagnostic tests may be used in severe cases or on patients who do not respond to the initial methods:

• Electromyography (or EMG). Used to confirm nerve damage or the extent of the facial nerves involved in the palsy. An electrode with a needle is placed through the skin into a muscle. The electrical activity of the muscle is recorded and displayed on a screen or played through a speaker. The EMG records the muscle’s ability to respond when nerves are stimulated.
  
  
• X-ray. A skull x-ray to look for infection or tumors can rule out those potential causes. An x-ray is a painless test in which an image is created of the skull by using low doses of electromagnetic radiation that are reflected on film paper or fluorescent screens.
  
  
  
  
• MRI (magnetic resonance imaging). Imaging test that can indicate pressure on the facial nerve in the bony passageway in the skull, the fallopian canal. It can also eliminate other possible causes of pressure on the facial nerves such as brain tumor or stroke. MRI is a noninvasive procedure that uses powerful magnets and radio waves to produce clear, cross-sectional or three-dimensional images of bodily tissues.
  
  
• CAT scan (computed axial tomography). Performed to rule out other causes of pressure on the facial nerve (e.g., brain tumor or stroke). A CAT scan is a noninvasive or minimally invasive test that uses a rotating x-ray device to create three-dimensional cross-sectional images of the brain and skull.
  
  
  
  
• Blood tests. To rule out other diseases such as Lyme disease or syphilis. Blood tests can detect the presence of antibodies to numerous conditions. Blood sugar levels may also be tested to determine if the patient has diabetes, which is a risk factor for Bell’s palsy.
  
  
• Hearing test. To determine the extent to which the patient’s hearing or the muscles in the inner ear are affected by the paralysis. Pure-tone tests, the most common hearing screening test, involves placing plugs into the ear canals and asking the patient to raise their hands when they hear a series of different tones.
  
  
• Spinal tap (lumbar puncture). To screen for signs of infection or bleeding. A fine, long needle is inserted into the lower back between the vertebrae directly into the spinal column. A sample of cerebrospinal fluid is drawn and analyzed for infectious agents.

There is no known cure for Bell’s palsy, nor is there a standard course of treatment for the disorder. Bell’s palsy has a range of varying symptoms, so each patient’s treatment varies. Many people recover within two weeks and require no special treatment other than protecting the eyes and massaging and lubricating the skin and muscles.

If treatment is necessary, eliminating the source of the nerve damage (e.g., the viral infection) is usually the first step. Treatment may include antiviral medications  and anti-inflammatory drugs such as corticosteroids to fight swelling. For pain that may accompany the condition, over-the-counter analgesics can be taken. Patients are advised to ask their physician about possible side effects or drug interactions before taking any prescription or over-the-counter medications or herbal supplements.

Some patients may be treated with injections of botulinum toxin. This chemical substance is most widely known for its use in cosmetic procedures to reduce facial wrinkles. However, botulinum toxin may be used to treat some patients who experience lingering effects of Bell’s palsy. It can help treat abnormal facial muscle movements and improve facial symmetry.

Patients who do not respond to treatment within three to four months may be considered for additional diagnostic tests to evaluate any other possible causes of the paralysis.

Many patients experience eye irritation or dryness caused by drooping eyelids that fail to lubricate the eyes. Artificial lubricants such as eye drops, artificial tears, eye ointments or gels may be recommended, in addition to wearing an eye patch or other protective covering over the weakened eye. Wearing a night patch will help ensure the cornea is not scratched during sleep.

Specific care methods may be recommended for the mouth, where areas may have no sensation or produce little or no saliva. Because saliva production is crucial to good oral hygiene, patients may be advised to rinse their mouths frequently and to brush and floss carefully to prevent injury to sensitive gums. Chewing food slowly and eating soft foods (i.e., soups, yogurt) will help avoid injury to the tongue.

The physician may recommend physical therapy to strengthen facial muscles and stimulate nerve response. Facial massage and exercises may help prevent permanent muscle damage during the paralysis. Some people apply moist heat to the paralyzed areas to help reduce pain, while others rub affected areas with creams or oils. Alternative and complementary therapies include relaxation exercises, acupuncture, electrical stimulation, biofeedback training and taking vitamins B12, B6 and zinc to promote nerve growth. However, these treatments have not been proven to be effective.

In rare cases, surgery to relieve pressure on facial nerves (called decompression surgery) has been performed as a treatment option. However, this procedure is controversial and may not be appropriate for everyone.

For the small number of people who do not fully recover from the disorder and are left with drooping eyelids, crooked smiles or other facial distortions, cosmetic or reconstructive surgery to correct the damage may be an option. Some of these procedures are controversial and include:

• Eyelift/facelift. Repositioning the upper and lower eyelids, eyebrows, cheeks or lips into symmetry with the rest of the face.
  
  
• Muscle graft. Muscle tissue from the leg is removed and placed in the facial cavity to bulk up the appearance of sagging, emaciated tissue and to replace nonviable facial muscles.
  
  
• Muscle transposition. Moving the temporalis muscle or masseter muscle (two adjacent facial muscles not controlled by the seventh cranial facial nerve) so that they connect to the corner of the mouth and improve facial movement.
  
  
• Nerve graft. Using nerve tissue from other sensory nerves (e.g., the great auricular or sural nerves) to replace damaged nerves in the affected areas.
  
  
• Nerve transposition. Moving the nerves in the tongue (the hypoglossal nerve) so that it connects with existing facial nerves to improve movement.

There are few prevention options for Bell’s palsy. Pregnant women may be advised to drink plenty of water to prevent bloating (which may put additional pressure on the facial nerve) and to avoid excess salt in the diets.

Preparing questions in advance can help patients have more meaningful discussions with healthcare professionals regarding their condition. Patients may wish to ask their doctor the following Bell’s palsy-related questions:

1. What caused my case of Bell’s palsy?
   
   
2. How can you be certain I have Bell’s palsy and not some other similar condition?
   
   
3. How long will my Bell’s palsy last?
   
   
4. What are my treatment options?
   
   
5. Will this condition affect my unborn baby?
   
   
6. Will prescription medications or herbal supplements I am currently taking affect my recovery?
   
   
7. Can you recommend any alternative treatment methods to speed my recovery or lessen my symptoms?
   
   
8. What measures should I take to protect my eyes from any permanent damage?
   
   
9. Will I need plastic surgery to repair any permanent damage caused by the paralysis?
   
   
10. What are the chances of a recurrence of my condition? How can I prevent this from happening?