Bell's palsy is a disorder of the nerve that controls movement of the muscles in the face. This nerve is called the facial or 7th cranial nerve.A.D.A.M.

Causes, incidence, and risk factors

Bell's palsy affects about 30,000 - 40,000 people a year in the United States.

Bell's palsy involves damage to the seventh cranial (facial) nerve. This nerve controls the movement of the muscles of the face.

Bell's palsy is thought to be due to swelling (inflammation) of this nerve in the area where it travels through the bones of the skull.

The cause is often not clear. A type of herpes infection called herpes zoster might be involved. Other conditions that may cause Bell's palsy include:

• HIV infection
• Lyme disease
• Middle ear infection
• Sarcoidosis

Symptoms

Sometimes you may have a cold shortly before the symptoms of Bell's palsy begin.

Symptoms most often start suddenly, but may take 2 - 3 days to show up. They do not become more severe after that.

Symptoms are almost always on one side of the face only. They may range from mild to severe.

The face will feel stiff or pulled to one side, and may look different. Other symptoms can include:

• Difficulty closing one eye
• Difficulty eating and drinking; food falls out of one side of the mouth
• Drooling due to lack of control over the muscles of the face
• Drooping of the face, such as the eyelid or corner of the mouth
• Problems smiling, grimacing, or making facial expressions
• Twitching or weakness of the muscles in the face

Other symptoms that may occur:

• Dry eye, which may lead to eye sores or infections
• Dry mouth
• Headache
• Loss of sense of taste
• Sound that is louder in one ear (hyperacusis)
• Twitching in face

Signs and tests

Often, Bell's palsy can be diagnosed just by taking a health history and doing a complete physical exam.

If your health care provider is worried that a brain tumor is causing your symptoms, you may need:

• CT scan of the head
• Magnetic resonance imaging (MRI) of the head

Sometimes, you will need a test to check the nerves that supply the muscles of your face:

• Electromyography (EMG)
• Nerve conduction test

Treatment

Often, no treatment is needed. Symptoms often begin to improve right away. However, it may take weeks or even months for the muscles to get stronger, and this may be frustrating.

Your health care provider may give you lubricating eye drops or eye ointments to keep the surface of the eye moist if you cannot close it completely. You may need to wear an eye patch while you sleep.

Sometimes medicines may be used, but it is not clear how much they help. If medicines are used, they should be started right away.

• Corticosteroids may reduce swelling around the facial nerve
• Medications can fight the virus that may be causing Bell's palsy

Surgery to relieve pressure on the nerve (decompression surgery) has not been shown to benefit most people with Bell's palsy.

Expectations (prognosis)

Most cases go away completely within a few weeks to months.

If you did not lose all of your nerve function and symptoms began to improve within 3 weeks, you're more likely to regain all or most of the strength in your facial muscles.

Sometimes, the following symptoms still may be present:

• Long-term changes in taste
• Spasms of muscles or eyelids
• Weakness that remains in facial muscles

Complications

Excess drying of the eye surface, leading to eye sores or infections.

Calling your health care provider

Call your health care provider right away if your face droops or you have other symptoms of Bell's palsy. Your health care provider can rule out other, more serious conditions, such as stroke.

Prevention

There is no known way to prevent Bell's palsy.

References

1. de Almeida JR, Al Khabori M, Guyatt GH, Witterick IJ, Lin VY, Nedzelski JM, et al. Combined corticosteroid and antiviral treatment for Bell palsy: a systematic review and meta-analysis. JAMA. 2009;302:985-993. [PubMed: 19724046]
2. McAllister K, Walker D, Donnan PT, Swan I. Surgical interventions for the early management of Bell's palsy. Cochrane Database Syst Rev. 2011 Feb 16;(2):CD007468. [PubMed: 21328293]

Review Date: 5/21/2012.

Reviewed by: Luc Jasmin, MD, PhD, Department of Neurosurgery at Cedars-Sinai Medical Center, Los Angeles, and Department of Anatomy, UCSF, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.