Bell's Palsy

Bell's palsy is the sudden onset of unilateral or one-sided facial paralysis of an unknown cause. The disorder affects the facial nerve which is responsible for facial muscle movement, taste for part of the tongue and tearing. This explains the Bell's palsy symptoms that include drooping of the eyelid or mouth, drooling, twitching, decreased tearing, increased sensitivity to sound and inability to close the eye fully in severe cases. All cases of acute onset of facial paralysis should be evaluated by a health care provider immediately.

It affects about 40,000 people in the U.S. annually or up to 34 people per 100,000. The risk for Bell's palsy increases during the third trimester of pregnancy and the first postpartum week. Suspected causes include the herpes simplex virus, which is responsible for fever blisters and genital herpes. Herpes zoster virus, CMV and the Epstein Barr virus are also believed to cause Bell's palsy.

Viruses cause inflammation and swelling of the facial nerve as it courses through the side of the face. As it swells it becomes constricted which impedes its ability to communicate from the brain to the muscle and hence the facial paralysis. The symptoms typically worsen over the first 3 weeks and then improve. Ninety percent of individuals with only partial paralysis, and 60% of those with complete paralysis go on to have complete recoveries.

Bell's palsy is diagnosed clinically, meaning that the judgment is based upon the patient's symptoms and physical examination only. There isn't any type of imaging or blood tests that will confirm the diagnosis. There is a poor prognosis for recovery if there is no improvement in symptoms after 6 months.

There isn't a cure for Bell's palsy, but there are a few treatment options if they are started early. These include antiviral medications and daily prednisone for one week. It is very important to treat an affected eye with daytime artificial tears and a moisturizing ointment at night. If the cornea becomes dry, there is an increased risk of sight loss. Tape should never be placed over the eyelid because it could slip and damage the cornea.

It is important to have close follow-up with the health care provider to ensure proper healing and to investigate other possibilities that could have caused the disorder. Prognosis increases dramatically if treatment was promptly started and symptoms have begun to resolve within 3 weeks.

Further information can be found at the National Institute of Neurological Disorders and Stroke at www.ninds.nig.gov/disorders/bells/detail_bells.htm.