|A person attempting to show his teeth and raise his eyebrows with Bell's palsy on his right side. Note how the forehead is not spared.|
|Specialty||Neurology, ENT, oral and maxillofacial surgery|
|Symptoms||Inability to move the facial muscles on one side, change in taste, pain around the ear|
|Usual onset||Over 48 hours|
|Duration||< 6 months|
|Risk factors||Diabetes, recent upper respiratory tract infection|
|Diagnostic method||Based on symptoms|
|Differential diagnosis||Brain tumor, stroke, Ramsay Hunt syndrome type 2, Lyme disease|
|Treatment||Corticosteroids, eye drops, eyepatch|
|Prognosis||Most recover completely|
|Frequency||1–4 per 10,000 per year|
Bell's palsy is a type of facial paralysis that results in a temporary inability to control the facial muscles on the affected side of the face. Symptoms can vary from mild to severe. They may include muscle twitching, weakness, or total loss of the ability to move one, and in rare cases, both sides of the face. Other symptoms include drooping of the eyelid, a change in taste, and pain around the ear. Typically symptoms come on over 48 hours. Bell's palsy can trigger an increased sensitivity to sound known as hyperacusis.
The cause of Bell's palsy is unknown. Risk factors include diabetes, a recent upper respiratory tract infection, and pregnancy. It results from a dysfunction of cranial nerve VII (the facial nerve). Many believe that this is due to a viral infection that results in swelling. Diagnosis is based on a person's appearance and ruling out other possible causes. Other conditions that can cause facial weakness include brain tumor, stroke, Ramsay Hunt syndrome type 2, myasthenia gravis, and Lyme disease.
The condition normally gets better by itself with most achieving normal or near-normal function. Corticosteroids have been found to improve outcomes, while antiviral medications may be of a small additional benefit. The eye should be protected from drying up with the use of eye drops or an eyepatch. Surgery is generally not recommended. Often signs of improvement begin within 14 days, with complete recovery within six months. A few may not recover completely or have a recurrence of symptoms.
Bell's palsy is the most common cause of one-sided facial nerve paralysis (70%). It occurs in 1 to 4 per 10,000 people per year. About 1.5% of people are affected at some point in their lives. It most commonly occurs in people between ages 15 and 60. Males and females are affected equally. It is named after Scottish surgeon Charles Bell (1774–1842), who first described the connection of the facial nerve to the condition.
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