Bell's palsy is a form of temporary facial paralysis resulting from damage or trauma to one of the two facial nerves. It is the most common cause of facial paralysis. Generally, Bell's palsy affects only one of the paired facial nerves and one side of the face, however, in rare cases, it can affect both sides. Symptoms of Bell's palsy usually begin suddenly and reach their peak within 48 hours. Symptoms range in severity from mild weakness to total paralysis and may include twitching, weakness, or paralysis, drooping eyelid or corner of the mouth, drooling, dry eye or mouth, impairment of taste, and excessive tearing in the eye. Bell’s palsy often causes significant facial distortion. Most scientists believe that a viral infection such as viral meningitis or the common cold sore virus -- herpes simplex-- causes the disorder when the facial nerve swells and becomes inflamed in reaction to the infection.
There is no cure or standard course of treatment for Bell's palsy. The most important factor in treatment is to eliminate the source of the nerve damage. Some cases are mild and do not require treatment since the symptoms usually subside on their own within 2 weeks. For others, treatment may include medications such as acyclovir -- used to fight viral infections -- combined with an anti-inflammatory drug such as the steroid prednisone -- used to reduce inflammation and swelling. Analgesics such as aspirin, acetaminophen, or ibuprofen may relieve pain, but because of possible drug interactions, patients should always talk to their doctors before taking any over-the-counter medicines. In general, decompression surgery for Bell's palsy -- to relieve pressure on the nerve -- is controversial and is seldom recommended.
The prognosis for individuals with Bell's palsy is generally very good. The extent of nerve damage determines the extent of recovery. With or without treatment, most individuals begin to get better within 2 weeks after the initial onset of symptoms and recover completely within 3 to 6 months.
Prepared by the National Institutes of Health