Bell palsy

Bell's palsy is a neurological disorder that causes paralysis or weakness on one side of the face. One of the nerves that controls muscles in your face becomes injured or stops working properly.

Symptoms include:

• Sudden weakness or paralysis on one side of your face
• A drooping eyebrow and mouth
• Drooling from one side of your mouth
• Difficulty closing an eyelid, which causes eye dryness

Most often these symptoms lead to significant facial distortions.

People living with Bell's palsy may also develop:

• Facial pain or abnormal sensations
• Excessive tearing in one eye
• Problems with taste
• Low tolerance for loud noises
• Pain around the jaw and behind the ear
• Problems eating or drinking

Symptoms appear suddenly over a 48- to 72-hour period and generally start to improve with or without treatment after a few weeks. They vary from person to person and can be mild to severe. Usually, you will recover some or all facial function within a few weeks to six months. Sometimes the facial weakness may last longer or be permanent.

Bell's palsy is the most common cause of facial paralysis, although its exact cause is unknown. It results from dysfunction of cranial nerve VII, which connects your brain to the muscles that control facial expression (the nerve also is involved with taste and ear sensation). In rare cases, Bell's palsy can affect both sides of your face.

Who is more likely to get Bell's palsy?

Bell's palsy is estimated to affect about 40,000 people in the United States every year. It can affect anyone of any gender and age but seems to be highest in those in people 15 to 45 years old. Risk factors for Bell's palsy include pregnancy, preeclampsia, obesity, hypertension, diabetes, and upper respiratory ailments.

Possible triggers of Bell's palsy may include:

• An existing (dormant) viral infection
• Impaired immunity from stress, sleep deprivation, physical trauma, minor illness, or autoimmune syndromes
• Infection of a facial nerve and resulting inflammation
• Damage to the myelin sheath (fatty covering that insulates nerve fibers)

How is Bell's palsy diagnosed and treated?

Diagnosing Bell's palsy. A doctor will examine you for any upper and lower facial muscle weakness on one side of your face (including the forehead, eyelid, and mouth) that began in less than 72 hours. During the exam, the doctor will rule out other possible causes of facial paralysis. There is no specific laboratory test to confirm diagnosis of the disorder.

Routine laboratory or imaging studies are not necessary for most cases, but sometimes they can help to confirm your diagnosis or rule out other diseases or conditions that can cause facial weakness (e.g., brain tumor, stroke, myasthenia gravis, and Lyme disease). If no specific cause can be identified, the condition can be diagnosed as Bell's palsy.

Tests for Bell's palsy may include:

• Electromyography (EMG), which uses thin wire electrodes that are inserted into a muscle to assess changes in electrical activity during movement and when the muscle is at rest. EMGs can confirm the presence of nerve damage and determine the severity and the extent of nerve involvement.
• Blood tests can sometimes help diagnose other concurrent problems such as diabetes and certain infections.
• Diagnostic imaging such as magnetic resonance imaging (MRI) or computed tomography (CT) scans can rule out other structural causes of pressure on the facial nerve (e.g., an artery compressing the nerve) and also check the other nerves.

Treating Bell's palsy

Medications

• Your doctor might prescribe steroids if you have new-onset Bell's palsy. In most instances, oral steroids should be started within 72 hours of symptom onset if possible, to reduce inflammation and swelling and increase the probability of recovering facial nerve function. Some people with Bell's palsy or facial weakness with co-existing conditions may not respond well to or be able to take steroids.
• Antiviral agents (in addition to steroids) might increase the probability of recovery of facial function, although their benefit has not been clearly established.
• Analgesics such as aspirin, acetaminophen, or ibuprofen may relieve pain. Because of possible drug interactions, individuals taking prescription medicines should always talk to their doctors before taking any over-the-counter (OTC) drugs.

Eye protection

• Keeping your eyes moist and protecting them from debris and injury, especially at night, is important. Lubricating eye drops, such as artificial tears or eye ointments or gels, and eye patches also are effective.

Other therapies

• Physical therapy, facial massage, or acupuncture may provide a small improvement with facial nerve function and pain. Electrical stimulation of the facial nerve may improve.

Surgery

• On rare occasions, cosmetic or reconstructive surgery may be needed to correct some damage such as an eyelid that will not fully close or a crooked smile.

What are the latest updates on Bell's palsy?

The National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health (NIH), is the nation's leading federal funder on neurological disorders. NINDS conducts and supports an extensive research program to increase understanding of how the nervous system works and what causes the system to sometimes go wrong. Part of this research program focuses on learning more about nerve mechanisms involved in facial movement and control and the circumstances that lead to nerve damage, such as facial paralysis. Knowledge gained from this research may help scientists find the definitive cause of Bell's palsy, leading to the discovery of new effective treatments.

Among NINDS-funded research on facial palsy, scientists hope to develop and study the long-term feasibility of an implanted functional electrical stimulator in the healthy side of the face to drive muscle movement in the paralyzed side of the face. Functional electric stimulation uses an electrical current to cause muscles to contract, which may lead to increased movement, muscle strength, and less pain.

Other scientists are studying a set of genes to identify the molecular mechanisms involved in the regeneration of nerve projections (axons) to their original targets. Peripheral nerves send and receive signals from the brain and spinal cord to the rest of the body, including signals to the muscles to tell them how to contract, which is how we move. Understanding how to regenerate peripheral nerves may lead to ways to prevent nerve damage and injuries.

For research articles and summaries on Bell's Palsy, search PubMed, which contains citations from medical journals and other sites.

How can I or my loved one help improve care for people with Bell's palsy?

Consider participating in a clinical trial so clinicians and scientists can learn more about Bell's palsy. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with Bell's palsy at Clinicaltrials.gov, a database of past and current clinical trials.

Where can I find more information about Bell's palsy?

The following organizations and resources can help individuals, families, friends, and caregivers of people living with Bell's palsy:

Genetic and Rare Diseases (GARD)
Phone: 888-205-2311

MedlinePlus

National Organization for Rare Disorders (NORD)
Phone: 203-744-0100 or 800-999- 6673

Content source: https://www.ninds.nih.gov/health-information/disorders/bells-palsy. Accessed July 11, 2023.

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