Bell's palsy | |
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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, Ophthalmology, ENT, oral and maxillofacial surgery |
Symptoms | Inability to move the facial muscles on one side, change in taste, pain around the ear[1] |
Usual onset | Over 48 hours[1] |
Duration | < 6 months[1] |
Causes | Unknown[1] |
Risk factors | Diabetes, recent upper respiratory tract infection[1] |
Diagnostic method | Based on symptoms[1] |
Differential diagnosis | Brain tumor, stroke, Ramsay Hunt syndrome type 2, Lyme disease[2] |
Treatment | Corticosteroids, eye drops, eyepatch[1][3] |
Prognosis | Most recover completely[1] |
Frequency | 1–4 per 10,000 per year[2] |
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.[1] In most cases, the weakness is temporary and significantly improves over weeks.[4] Symptoms can vary from mild to severe.[1] They may include muscle twitching, weakness, or total loss of the ability to move one or, in rare cases, both sides of the face.[1] Other symptoms include drooping of the eyebrow,[5] a change in taste, and pain around the ear. Typically symptoms come on over 48 hours.[1] Bell's palsy can trigger an increased sensitivity to sound known as hyperacusis.[6]
The cause of Bell's palsy is unknown[1] and it can occur at any age.[4] Risk factors include diabetes, a recent upper respiratory tract infection, and pregnancy.[1][7] It results from a dysfunction of cranial nerve VII (the facial nerve).[1] Many believe that this is due to a viral infection that results in swelling.[1] Diagnosis is based on a person's appearance and ruling out other possible causes.[1] Other conditions that can cause facial weakness include brain tumor, stroke, Ramsay Hunt syndrome type 2, myasthenia gravis, and Lyme disease.[2]
The condition normally gets better by itself, with most achieving normal or near-normal function.[1] Corticosteroids have been found to improve outcomes, while antiviral medications may be of a small additional benefit.[8] The eye should be protected from drying up with the use of eye drops or an eyepatch.[1] Surgery is generally not recommended.[1] Often signs of improvement begin within 14 days, with complete recovery within six months.[1] A few may not recover completely or have a recurrence of symptoms.[1]
Bell's palsy is the most common cause of one-sided facial nerve paralysis (70%).[2][9] It occurs in 1 to 4 per 10,000 people per year.[2] About 1.5% of people are affected at some point in their lives.[10] It most commonly occurs in people between ages 15 and 60.[1] Males and females are affected equally.[1] It is named after Scottish surgeon Charles Bell (1774–1842), who first described the connection of the facial nerve to the condition.[1]
Although defined as a mononeuritis (involving only one nerve), people diagnosed with Bell's palsy may have "myriad neurological symptoms", including "facial tingling, moderate or severe headache/neck pain, memory problems, balance problems, ipsilateral limb paresthesias, ipsilateral limb weakness, and a sense of clumsiness" that are "unexplained by facial nerve dysfunction".[11]
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