Definition

Bell’s palsy is a condition characterized by paralysis of the facial muscles on one side. This paralysis is confined to the face and is caused by a problem with the nerve that controls the movement of facial muscles. The incidence rate of Bell’s palsy is approximately 15-20 cases per 100,000 people per year.

Causes

Nerves have various functions, including transmitting sensory stimuli and moving the innervated body parts (motor function). In Bell’s palsy, the affected nerve is the motor nerve that controls facial muscle movements. This disorder only occurs on one side of the face.

The exact cause of Bell’s palsy is unknown. However, Bell’s palsy has been linked to viral infections such as herpes simplex virus (causing herpes), varicella-zoster virus (causing chickenpox and shingles), and Epstein-Barr virus (causing mononucleosis). These factors cause the nerve to become inflamed and swollen. This swelling compresses the nerve that controls facial movement, resulting in paralysis on one side of the face.

Risk factor

Bell’s palsy can occur at any age but is most commonly found in adults, with a median age of 40 years. Bell’s palsy can also occur in any race. Risk factors for Bell’s palsy include a history of viral infections, diabetes, pregnancy, obesity, and hypertension. Women with a history of high blood pressure during late pregnancy (preeclampsia) also have a higher risk of developing Bell’s palsy.

Symptoms

The symptoms of Bell’s palsy are very characteristic, with weakness or paralysis on one side of the face that appears quickly, within a few days, reaching its peak by the third day (72 hours). This weakness or paralysis makes it difficult to wrinkle the forehead, close the eyes completely, smile, and close the mouth. In addition to muscle weakness or paralysis, other symptoms may include continuous drooling from the corner of the mouth, dry eyes, dry mouth, decreased taste sensation on the tongue, headaches, and increased sensitivity to sound in the affected ear.

Diagnosis

Bell’s palsy is usually diagnosed through a physical examination. Before the examination, the doctor may ask about risk factors related to Bell’s palsy. The doctor may then ask you to perform various facial expressions such as wrinkling your forehead, raising your eyebrows, closing your eyes tightly, and smiling broadly to assess muscle weakness in the face and identify which muscles are affected.

However, since facial muscle weakness can occur in conditions other than Bell’s palsy, such as stroke, Lyme disease, infection, or tumors, other tests may be necessary. The doctor may perform an electromyography (EMG) to evaluate nerve conduction in the affected area, predicting recovery, especially in severe cases. If there are symptoms like ringing in the ears, hearing loss, and vertigo, the doctor may conduct hearing tests (audiography) and nerve examinations of the ear. Imaging tests such as CT scans or MRIs may also be done to rule out other causes of nerve compression, like tumors or skull fractures.

Another test that can be performed is the tear break-up time (TBUT), which assesses whether the tear film is sufficient to protect the eye from foreign objects and germs. In Bell’s palsy patients, incomplete eyelid closure can lead to dry eyes or injuries from foreign objects, germs, etc.

Management

Bell’s palsy can recover on its own with or without medication. However, medications can speed up recovery. Typically, doctors prescribe steroids for 7-10 days to reduce nerve inflammation and relieve nerve compression. If a viral infection is suspected, antiviral medications may be given to reduce the infection.

Additionally, there are several self-care measures you can take at home:

• Use an eye patch for the eye that won’t close properly to prevent injury from foreign objects or nails.
• Use artificial tear drops. If the eye doesn’t close well, tear circulation is reduced, leading to dryness, injury, and infection. Artificial tear drops used 4-6 times a day can help keep the eye protected.
• Take pain relievers like acetaminophen and ibuprofen to alleviate pain caused by Bell’s palsy.
• Do facial exercises and massages. A doctor may refer you to a physical therapist to learn facial exercises and massages, which can help relax weakened muscles and prevent them from becoming stiff.

In some cases, Bell’s palsy may persist for more than three months. If this happens, further examinations and possibly surgery may be necessary to release the compressed nerve. However, this surgery carries risks, such as permanent facial nerve damage and hearing loss.

Complications

Complications of Bell’s palsy can occur during the illness or afterward. Bell’s palsy causes difficulty in closing the eyelids, leading to tear film evaporation and dry eyes, which can result in eye surface injuries and vision problems. Additionally, nerve damage in Bell’s palsy can be lifelong. Another complication is abnormal nerve fiber growth, which can cause abnormal facial movements. For example, when you smile, the eye on the affected side might also close.

Prevention

Bell’s palsy cannot be prevented as it is generally associated with viral infections, but not all viral infections cause Bell’s palsy. However, you can prevent complications by using an eye patch and artificial tear drops to prevent dry eyes or exposure to foreign objects and performing facial exercises to prevent muscle stiffness. Usually, Bell’s palsy only occurs once in a lifetime, but it can recur. A family history of recurrent Bell’s palsy increases your risk of experiencing the same.

When to see a doctor?

If you experience paralysis on one side of the face, see a doctor immediately. This paralysis could be a symptom of Bell’s palsy but could also be due to other conditions like a stroke, especially if the paralysis doesn’t involve the forehead or is accompanied by slurred speech and weakness on one side of the body. Remember, Bell’s palsy is not caused by a stroke. Bell’s palsy is only diagnosed when no other conditions can explain the facial muscle paralysis.

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