Because of this, people with Bells palsy may present with loss of taste sensation in the anterior 2⁄3 of the tongue on the affected side.Although the facial nerve innervates the stapedius muscle of the middle ear (through the tympanic branch), sound sensitivity, causing normal sounds to be perceived as very loud (hyperacusis), and dysacusis are possible but hardly ever clinically evident.Although defined as a mononeuritis (involving only one nerve), people diagnosed with Bells 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". Cause
The cause of Bells palsy is unknown. Risk factors include diabetes, a recent upper respiratory tract infection, and pregnancy.Some viruses are thought to establish a persistent (or latent) infection without symptoms, e.g., the varicella zoster virus and the Epstein–Barr virus, both of the herpes family. Reactivation of an existing (dormant) viral infection has been suggested as a cause of acute Bells palsy. As the facial nerve swells and becomes inflamed in reaction to the infection, it causes pressure within the Fallopian canal, resulting in the restriction of blood and oxygen to the nerve cells. Other viruses and bacteria that have been linked to the development of Bells palsy include HIV, sarcoidosis and Lyme Disease. This new activation could be triggered by trauma, environmental factors, and metabolic or emotional disorders.Familial inheritance has been found in 4–14% of cases.
Bells 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. In most cases, the weakness is temporary and significantly improves over weeks. Symptoms can vary from mild to severe. They may include muscle twitching, weakness, or total loss of the ability to move one or, 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. Bells palsy can trigger an increased sensitivity to sound known as hyperacusis.The cause of Bells palsy is unknown and it can occur in any age. 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 persons 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.