Bell's palsy

Introduction 

Bell's palsy is a condition that causes temporary weakness or paralysis of the muscles on one side of the face. It is the most common cause of facial paralysis.

Other causes of facial paralysis include:

• Congenital facial palsy—children born with facial weakness
• Injury to the facial nerve in an accident—such as a cut to the cheek or a skull base fracture
• Injury from surgery—most common during surgery of the parotid gland and neck

What are the symptoms?

The symptoms vary from person to person. The weakness on one side of the face can be described as either:

• Partial, which is mild muscle weakness
• Complete, which is no movement at all (paralysis)—although this is very rare

It can also affect the eyelid and mouth, making it difficult to close or open them. In rare cases, it can affect both sides of the face.

Why does it happen?

Bell's palsy is believed to occur when the nerve that controls the muscles in your face becomes compressed. The exact cause is unknown, but it is thought that the facial nerve becomes inflamed, possibly due to a viral infection.

The herpes virus is thought to be the most common cause, although other viruses may also be responsible.

Who is affected?

It is a rare condition, affecting about one in 5,000 people each year. It is most common in people aged 15–60, but those outside this age group can also suffer from the condition. Men and women are equally affected.

Treatment

Around 7 out of 10 people make a complete recovery, with or without treatment.

Most people notice an improvement in their symptoms after two to three weeks, but a complete recovery can take up to nine months. Recovery time varies from person to person and depends on the extent of nerve damage.

Prednisolone, a type of corticosteroid, is used to reduce swelling of the facial nerve.

Eye drops may be necessary if you are unable to close your eye, and tape may be used to close the eye while sleeping.

Complications

Around 3 in 10 people continue to experience weakness in their facial muscles, and 2 in 10 are left with more serious long-term problems. Complications can include:

• Persistent facial weakness
• Eye problems
• Difficulty with speech, eating and drinking
• Reduced sense of taste
• Facial muscle twitching

Up to 1 in 7 people may experience a reoccurrence, especially if there is a family history of the condition.