Bell’s palsy is a temporary facial paralysis that affects movements like smiling and blinking, resulting in a droopy effect. It is caused by nerve damage that interrupts the relay of messages from the brain to the face - usually on just one side of the face. This condition was named after the surgeon who first identified it in the 19th century, Sir Charles Bell.
Each year, roughly 40,000 Americans suffer from Bell’s palsy (usually between the age of 15 and 60). Bell’s palsy is not life threatening and most individuals fully recover by six months, although in rare cases symptoms persist for life.
Causes and Risk Factors
Bell’s palsy is caused by inflammation or compression of the facial nerve (cranial nerve VII), which controls the muscles of the face. Infection by a virus is believed to cause swelling and inflammation of the nerve, which in turn restricts the flow of oxygenated blood through the narrow canals (known as the facial or Fallopian canals) holding the nerves on either side of the face near the ears. Numerous viruses from the herpesvirus family are associated with Bell’s palsy.
Bell’s palsy has been associated with the following:
Herpesviruses: Herpes simplex 1 (cold sores), varicella-zoster (chicken pox and shingles), Epstein-Barr (mononucleosis) and cytomegalovirus.
Other possible viruses: Influenza B (flu), rubella (German measles), adenovirus (respiratory illness), coxsackievirus (hand-foot-mouth disease) and mumps.
Non-viral: Headaches, chronic ear infection, tumors, diabetes and injury to the face.
Bell’s palsy affects the function of facial muscles, as well as tears, saliva, taste and the middle ear. The condition is often recognized by droopiness on one side of the face, with symptoms that suddenly appear and peak after about one day. The symptoms of Bell’s palsy include:
Sudden weakness or paralysis on one side of the face
Difficulty smiling or closing the eyelid on the affected side
Jaw or ear pain on the affected side
Dryness in the eye and mouth
Ringing in the ear or sensitivity to sound
Impaired speech or taste
Difficulty eating and drinking
Reduced tear production.
Diagnosing Bell’s palsy starts with a medical examination of the face for signs of paralysis. During a typical exam the patient is asked to perform simple tasks like closing the eyes and smiling. Other tests that evaluate the face for nerve damage or trauma may be performed.
Electromyography (EMG). This test measures how well the facial muscles conduct electrical signals, and determines the presence/extent of nerve damage in the face.
Imaging. Magnetic resonance imaging (MRI) or computed tomography (CT) scans provide a detailed image of the face and show physical factors affecting the facial nerves, such as a tumor or an injury.
Blood test. Blood tests are performed to assess the patient for diabetes or evidence of and infection.
Treatment and Prevention
Treatment for Bell’s palsy depends on the severity of the disease and type of symptoms - many recover without medication. Anti-inflammatory drugs and/or antiviral therapies are commonly indicated, although some studies question the effectiveness of this treatment regimen. Symptoms generally begin to diminish within two weeks, with complete recovery by six months.
Anti-inflammatory drugs. Corticosteroids, like prednisone help reduce nerve inflammation and restore blood flow in the bony canal that holds the affected nerve.
Anti-viral drugs. Antiviral drugs such as acyclovir (Zovirax®) are prescribed to treat a viral infection, especially in cases of severe facial paralysis.
Surgery. The bony canals that hold the inflamed nerves can be widened with surgery, but this procedure is no longer common. Plastic surgery may be performed to correct permanent deformity to the affected area of the face.
Physical therapy. Muscle atrophy affects muscles that are not in use due to paralysis or injury. Regular physical therapy to exercise these muscles helps prevent muscle loss in the affected regions of the face.
At-home remedies. Over-the-counter pain medications and warm compresses can help relieve inflammation and facial pain. Artificial lubrication and eye covering (e.g. goggles or glasses) help protect the eye when the eyelid cannot fully close.
The best way to prevent Bell’s palsy is by avoiding viral infections and injury to the face. A healthy diet and regular exercise also help prevent other possible risk factors for the disease, such as diabetes.
“Bell’s Palsy Fact Sheet”. National Institute of Neurological Disorders and Stroke (NINDS). Retrieved Oct 12, 2014. http://www.ninds.nih.gov/disorders/bells/detail_bells.htm#259373050.
“Bells palsy”. Mayo Clinic Foundation. Retrieved Oct 12, 2014. http://www.mayoclinic.org/diseases-conditions/bells-palsy/basics/definition/con-20020529.
“What to do about Bell’s palsy”. Harvard Health Publications. Harvard Medical School. Retrieved Oct 12, 2014. http://www.harvardhealthcontent.com/newsletters/69,W0110c.
Sullivan FM, Swan IR, Donnan PT, Morrison JM, Smith BH, McKinstry B, Davenport RJ, Vale LD, Clarkson JE, Hammersley V, Hayavi S, McAteer A, Stewart K, Daly F. “Early treatment with prednisolone or acyclovir in Bell’s palsy.” N Engl J Med. 2007. 357(16):1598-607.
Tina is a Life Science Writer for a number of online publications, including Innerbody.com. Her expertise is in conveying complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. In her spare time, she enjoys drawing science-related cartoons.