Bell's palsy is a type of

facial paralysis Facial nerve paralysis is a common problem that involves the paralysis of any structures innervated by the facial nerve. The pathway of the facial nerve is long and relatively convoluted, so there are a number of causes that may result in facial ...

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 The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste (flavor). Taste is the perception produced or stimulated when a substance in the mouth reacts chemically with taste receptor ...

, 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 and it can occur in any age. Risk factors include

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

, a recent upper respiratory tract infection, and

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ca ...

. It results from a dysfunction of

cranial nerve VII The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of tas ...

(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 A brain tumor occurs when abnormal cells form within the brain. There are two main types of tumors: malignant tumors and benign (non-cancerous) tumors. These can be further classified as primary tumors, which start within the brain, and seconda ...

stroke A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...

, Ramsay Hunt syndrome type 2,

myasthenia gravis Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, dro ...

, and

Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the ''Borrelia'' bacterium, which is spread by ticks in the genus ''Ixodes''. The most common sign of infection is an expanding red rash, known as erythema migran ...

. The condition normally gets better by itself, with most achieving normal or near-normal function.

Corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are involv ...

s 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 An eyepatch is a small patch that is worn in front of one eye. It may be a cloth patch attached around the head by an elastic band or by a string, an adhesive bandage, or a plastic device which is clipped to a pair of glasses. It is often worn ...

. 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 Sir Charles Bell (12 November 177428 April 1842) was a Scotland, Scottish surgeon, anatomist, physiologist, neurologist, artist, and philosophical theologian. He is noted for discovering the difference between sensory nerves and motor nerves in ...

(1774–1842), who first described the connection of the facial nerve to the condition.

Signs and symptoms

Bell's palsy is characterized by a one-sided facial droop that comes on within 72 hours. In rare cases (<1%), it can occur on both sides resulting in total facial paralysis. The facial nerve controls a number of functions, such as blinking and closing the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

s, smiling, frowning, lacrimation,

salivation Saliva (commonly referred to as spit) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be e ...

, flaring nostrils and raising

eyebrow An eyebrow is an area of short hairs above each eye that follows the shape of the lower margin of the brow ridges of some mammals. In humans, eyebrows serve two main functions: first, communication through facial expression, and second, prevent ...

s. It also carries

sensations from the anterior two-thirds of the

tongue The tongue is a muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper surfa ...

, through the

chorda tympani nerve The chorda tympani is a branch of the facial nerve that originates from the taste buds in the front of the tongue, runs through the middle ear, and carries taste messages to the brain. It joins the facial nerve (cranial nerve VII) inside the facia ...

(a branch of the facial nerve). Because of this, people with Bell's palsy may present with loss of taste sensation in the anterior of the tongue on the affected side. Although the facial nerve innervates the stapedius muscle of the middle ear (through the

tympanic branch The tympanic nerve (Jacobson’s nerve) is a branch of the glossopharyngeal nerve found near the ear. It gives sensation to the middle ear, the Eustachian tube, the parotid gland, and mastoid air cells. It gives parasympathetic to supply to the p ...

), sound sensitivity, causing normal sounds to be perceived as very loud ( hyperacusis), and

dysacusis Dysacusis is a hearing impairment characterized by difficulty in processing details of sound due to distortion in frequency or intensity rather than primarily a loss of the ability to perceive sound. The term is sometimes used to describe pain or d ...

are possible but hardly ever clinically evident. 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".

Cause

The cause of Bell's palsy is unknown. Risk factors include

, a recent upper respiratory tract infection, and

. Some viruses are thought to establish a persistent (or latent) infection without symptoms, e.g., the

varicella zoster virus Varicella-zoster virus (VZV), also known as human herpesvirus 3 (HHV-3, HHV3) or ''Human alphaherpesvirus 3'' (taxonomically), is one of nine known herpes viruses that can infect humans. It causes chickenpox (varicella) commonly affecting chil ...

and the

Epstein–Barr virus The Epstein–Barr virus (EBV), formally called ''Human gammaherpesvirus 4'', is one of the nine known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. EBV is a double-stranded DNA virus. It is b ...

, both of the herpes family. Reactivation of an existing (dormant) viral infection has been suggested as a cause of acute Bell's 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 Bell's palsy include

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

sarcoidosis Sarcoidosis (also known as ''Besnier-Boeck-Schaumann disease'') is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly af ...

and

Lyme Disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the ''Borrelia'' bacterium, which is spread by ticks in the genus ''Ixodes''. The most common sign of infection is an expanding red rash, known as erythema migran ...

. 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. There may also be an association with

migraines Migraine (, ) is a common neurological disorder characterized by recurrent headaches. Typically, the associated headache affects one side of the head, is pulsating in nature, may be moderate to severe in intensity, and could last from a few hou ...

. In December 2020, the U.S.

FDA The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food s ...

recommended that recipients of the

Pfizer Pfizer Inc. ( ) is an American multinational pharmaceutical and biotechnology corporation headquartered on 42nd Street in Manhattan, New York City. The company was established in 1849 in New York by two German entrepreneurs, Charles Pfizer ...

and Moderna COVID-19 vaccines should be monitored for symptoms of Bell's palsy after several cases were reported among clinical trial participants, though the data were not sufficient to determine a causal link.

Genetics

A meta-analysis of genome-wide association study (GWAS) identified the first unequivocal association with Bell's palsy.

Pathophysiology

Bell's palsy is the result of a malfunction of the facial nerve (

cranial nerve Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and ...

VII), which controls the

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...

s of the face. Facial palsy is typified by inability to move the muscles of facial expression. The paralysis is of the infranuclear/lower motor neuron type. It is thought that as a result of

inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...

of the facial nerve, pressure is produced on the nerve where it exits the skull within its bony canal (the

stylomastoid foramen The stylomastoid foramen is a foramen between the styloid and mastoid processes of the temporal bone of the skull. It is the termination of the facial canal, and transmits the facial nerve, and stylomastoid artery. Facial nerve inflammation in th ...

), blocking the transmission of neural signals or damaging the nerve. Patients with facial palsy for which an underlying cause can be found are not considered to have Bell's palsy ''per se''. Possible causes of facial paralysis include

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...

diabetes mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

, head trauma and inflammatory diseases of the cranial nerves (

, brucellosis, etc.). In these conditions, the neurologic findings are rarely restricted to the facial nerve. Babies can be born with facial palsy. In a few cases, bilateral facial palsy has been associated with

acute HIV infection The stages of HIV infection are acute infection (also known as primary infection), latency and AIDS. Acute infection lasts for several weeks and may include symptoms such as fever, swollen lymph nodes, inflammation of the throat, rash, muscle ...

. In some research, the

herpes simplex virus Herpes simplex virus 1 and 2 (HSV-1 and HSV-2), also known by their taxonomical names ''Human alphaherpesvirus 1'' and '' Human alphaherpesvirus 2'', are two members of the human ''Herpesviridae'' family, a set of viruses that produce viral inf ...

type 1 (HSV-1) has been identified in a majority of cases diagnosed as Bell's palsy through endoneurial fluid sampling. Other research, however, identified, out of a total of 176 cases diagnosed as Bell's palsy, HSV-1 in 31 cases (18%) and

herpes zoster Shingles, also known as zoster or herpes zoster, is a viral disease characterized by a painful skin rash with blisters in a localized area. Typically the rash occurs in a single, wide mark either on the left or right side of the body or face. ...

in 45 cases (26%). In addition, HSV-1 infection is associated with demyelination of nerves. This nerve damage mechanism is different from the above-mentioned—that edema, swelling and compression of the nerve in the narrow bone canal is responsible for nerve damage. Demyelination may not even be directly caused by the virus, but by an unknown

immune In biology, immunity is the capability of multicellular organisms to resist harmful microorganisms. Immunity involves both specific and nonspecific components. The nonspecific components act as barriers or eliminators of a wide range of pathogens ...

response.

Diagnosis

Bell's palsy is a

diagnosis of exclusion A diagnosis of exclusion or by exclusion (''per exclusionem'') is a diagnosis of a medical condition reached by a process of elimination, which may be necessary if presence cannot be established with complete confidence from history, examination or ...

, meaning it is diagnosed by elimination of other reasonable possibilities. By definition, no specific cause can be determined. There are no routine lab or imaging tests required to make the diagnosis. The degree of nerve damage can be assessed using the House-Brackmann score. One study found that 45% of patients are not referred to a specialist, which suggests that Bell's palsy is considered by physicians to be a straightforward diagnosis that is easy to manage. Other conditions that can cause similar symptoms include

, and

Differential diagnosis

Once the facial paralysis sets in, many people may mistake it as a symptom of a stroke; however, there are a few subtle differences. A stroke will usually cause a few additional symptoms, such as numbness or weakness in the arms and legs. And unlike Bell's palsy, a stroke will usually let patients control the upper part of their faces. A person with a stroke will usually have some wrinkling of their forehead. In areas where

is common, it accounts for about 25% of cases of facial palsy. In the U.S., Lyme is most common in the

New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...

and Mid-Atlantic states and parts of

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

and

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...

. The first sign of about 80% of Lyme infections, typically one or two weeks after a tick bite, is usually an expanding rash that may be accompanied by headaches, body aches, fatigue, or fever. In up to 10–15% of Lyme infections, facial palsy appears several weeks later, and may be the first sign of infection that is noticed as the Lyme rash typically does not itch and is not painful. The likelihood that the facial palsy is caused by Lyme disease should be estimated, based on recent history of outdoor activities in likely tick habitats during warmer months, recent history of rash or symptoms such as headache and fever, and whether the palsy affects both sides of the face (much more common in Lyme than in Bell's palsy). If that likelihood is more than negligible, a serological test for Lyme disease should be performed, and if it exceeds 10%,

empiric therapy Empiric therapy or empirical therapy is medical treatment or therapy based on experience and, more specifically, therapy begun on the basis of a clinical "educated guess" in the absence of complete or perfect information. Thus it is applied before ...

with antibiotics should be initiated, without

corticosteroids Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are involve ...

, and reevaluated upon completion of laboratory tests for Lyme disease. Corticosteroids have been found to harm outcomes for facial palsy caused by Lyme disease. One disease that may be difficult to exclude in the

differential diagnosis In healthcare, a differential diagnosis (abbreviated DDx) is a method of analysis of a patient's history and physical examination to arrive at the correct diagnosis. It involves distinguishing a particular disease or condition from others that p ...

is involvement of the facial nerve in infections with the

virus. The major differences in this condition are the presence of small blisters, or ''vesicles'', on the external ear, significant pain in the jaw, ear, face and/or neck and hearing disturbances, but these findings may occasionally be lacking (

zoster sine herpete Shingles, also known as zoster or herpes zoster, is a viral disease characterized by a painful skin rash with blisters in a localized area. Typically the rash occurs in a single, wide mark either on the left or right side of the body or face. ...

). Reactivation of existing

infection leading to facial paralysis in a Bell's palsy type pattern is known as Ramsay Hunt syndrome type 2. The prognosis for Bell's palsy patients is generally much better than for Ramsay Hunt syndrome type 2 patients.

Treatment

Steroids have been shown to be effective at improving recovery in Bell's palsy while antivirals have not. In those who are unable to close their eyes, eye protective measures are required. Management during pregnancy is similar to management in the non-pregnant.

Steroids

s such as prednisone improve recovery at 6 months and are thus recommended. Early treatment (within 3 days after the onset) is necessary for benefit with a 14% greater probability of recovery.

Antivirals

One review found that antivirals (such as aciclovir) are ineffective in improving recovery from Bell's palsy beyond steroids alone in mild to moderate disease. Another review found a benefit when combined with corticosteroids but stated the evidence was not very good to support this conclusion. In severe disease it is also unclear. One 2015 review found no effect regardless of severity. Another review found a small benefit when added to steroids. They are commonly prescribed due to a theoretical link between Bell's palsy and the herpes simplex and

. There is still the possibility that they might result in a benefit less than 7% as this has not been ruled out.

Eye protection

When Bell's palsy affects the blink reflex and stops the eye from closing completely, frequent use of tear-like eye drops or eye ointments is recommended during the day and protecting the eyes with patches or taping them shut is recommended for sleep and rest periods.

Physiotherapy

Physiotherapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, patient ...

can be beneficial to some individuals with Bell's palsy as it helps to maintain

muscle tone In physiology, medicine, and anatomy, muscle tone (residual muscle tension or tonus) is the continuous and passive partial muscle contraction, contraction of the muscles, or the muscle's resistance to passive stretch during resting state.O’Sull ...

of the affected

facial muscles The facial muscles are a group of striated skeletal muscles supplied by the facial nerve (cranial nerve VII) that, among other things, control facial expression. These muscles are also called mimetic muscles. They are only found in mammals, alth ...

and stimulate the facial nerve. It is important that muscle re-education exercises and soft tissue techniques be implemented prior to recovery in order to help prevent permanent

contractures In pathology, a contracture is a permanent shortening of a muscle or joint. It is usually in response to prolonged hypertonic spasticity in a concentrated muscle area, such as is seen in the tightest muscles of people with conditions like spasti ...

of the paralyzed facial muscles. To reduce

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

, heat can be applied to the affected side of the face. There is no high quality evidence to support the role of electrical stimulation for Bell's palsy.

Surgery

Surgery may be able to improve outcomes in facial nerve palsy that has not recovered. A number of different techniques exist. Smile surgery or smile reconstruction is a surgical procedure that may restore the smile for people with facial nerve paralysis. Adverse effects include hearing loss which occurs in 3–15% of people. A Cochrane review (updated in 2021), after reviewing applicable randomized and quasi-randomized controlled trials was unable to determine if early surgery is beneficial or harmful. As of 2007 the American Academy of Neurology did not recommend surgical decompression.

Alternative medicine

The efficacy of acupuncture remains unknown because the available studies are of low quality (poor primary study design or inadequate reporting practices). There is very tentative evidence for hyperbaric oxygen therapy in severe disease.

Prognosis

Most people with Bell's palsy start to regain normal facial function within 3 weeks—even those who do not receive treatment. In a 1982 study, when no treatment was available, of 1,011 patients, 85% showed first signs of recovery within 3 weeks after onset. For the other 15%, recovery occurred 3–6 months later. After a follow-up of at least one year or until restoration, complete recovery had occurred in more than two-thirds (71%) of all patients. Recovery was judged moderate in 12% and poor in only 4% of patients. Another study found that incomplete palsies disappear entirely, nearly always in the course of one month. The patients who regain movement within the first two weeks nearly always remit entirely. When remission does not occur until the third week or later, a significantly greater part of the patients develop

sequela A sequela (, ; usually used in the plural, sequelae ) is a pathological condition resulting from a disease, injury, therapy, or other trauma. Derived from the Latin word, meaning “sequel”, it is used in the medical field to mean a complication ...

e. A third study found a better prognosis for young patients, aged below 10 years old, while the patients over 61 years old presented a worse prognosis. Major possible complications of the condition are chronic loss of taste ( ageusia), chronic facial spasm, facial pain and corneal infections. Another complication can occur in case of incomplete or erroneous regeneration of the damaged facial nerve. The nerve can be thought of as a bundle of smaller individual nerve connections that branch out to their proper destinations. During regrowth, nerves are generally able to track the original path to the right destination—but some nerves may sidetrack leading to a condition known as

synkinesis Synkinesis is a neurological symptom in which a voluntary muscle movement causes the simultaneous involuntary contraction of other muscles. An example might be smiling inducing an involuntary contraction of the eye muscles, causing a person to squ ...

. For instance, regrowth of nerves controlling muscles attached to the eye may sidetrack and also regrow connections reaching the muscles of the mouth. In this way, movement of one also affects the other. For example, when the person closes the eye, the corner of the mouth lifts involuntarily. Around 9% of people have some sort of ongoing problems after Bell's palsy, typically the synkinesis already discussed, or spasm, contracture, tinnitus or hearing loss during facial movement or crocodile-tear syndrome. This is also called gustatolacrimal reflex or

Bogorad's syndrome Tears are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all land mammals. Tears are made up of water, electrolytes, proteins, lipids, and mucins that form layers on the surface of eyes. The different types of ...

and results in shedding tears while eating. This is thought to be due to faulty regeneration of the facial nerve, a branch of which controls the lacrimal and salivary glands. Gustatorial sweating can also occur.

Epidemiology

The number of new cases of Bell's palsy ranges from about one to four cases per 10,000 population per year. The rate increases with age. Bell's palsy affects about 40,000 people in the United States every year. It affects approximately 1 person in 65 during a lifetime. A range of annual incidence rates have been reported in the literature: 15, 24, and 25–53 (all rates per 100,000 population per year). Bell's palsy is not a

reportable disease A notifiable disease is any disease that is required by law to be reported to government authorities. The collation of information allows the authorities to monitor the disease, and provides early warning of possible outbreaks. In the case of live ...

, and there are no established registries for people with this diagnosis, which complicates precise estimation.

Frequency

About 40,000 people are affected by Bell's Palsy in the United States every year. It can affect anyone of any gender and age, but its incidence seems to be highest in those in the 15- to 45-year-old age group.

History

The Persian physician

Muhammad ibn Zakariya al-Razi Abū Bakr al-Rāzī (full name: ar, أبو بکر محمد بن زکریاء الرازي, translit=Abū Bakr Muḥammad ibn Zakariyyāʾ al-Rāzī, label=none), () rather than ar, زکریاء, label=none (), as for example in , or in . In m ...

(865–925) detailed the first known description of peripheral and central facial palsy. Cornelis Stalpart van der Wiel (1620–1702) in 1683 gave an account of Bell's palsy and credited the Persian physician

Ibn Sina Ibn Sina ( fa, ابن سینا; 980 – June 1037 CE), commonly known in the West as Avicenna (), was a Persian polymath who is regarded as one of the most significant physicians, astronomers, philosophers, and writers of the Islamic G ...

(980–1037) for describing this condition before him. James Douglas (1675–1742) and Nicolaus Anton Friedreich (1761–1836) also described it. Scottish neurophysiologist Sir

read his paper to the

Royal Society of London The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

on July 12, 1821, describing the role of the facial nerve. He became the first to detail the neuroanatomical basis of facial paralysis. Since then, idiopathic peripheral facial paralysis has been referred to as Bell's palsy, named after him. A notable person with Bell's palsy is former

Prime Minister of Canada The prime minister of Canada (french: premier ministre du Canada, link=no) is the head of government of Canada. Under the Westminster system, the prime minister governs with the Confidence and supply, confidence of a majority the elected Hou ...

Jean Chrétien Joseph Jacques Jean Chrétien (; born January 11, 1934) is a Canadian lawyer and politician who served as the 20th prime minister of Canada from 1993 to 2003. Born and raised in Shawinigan Falls, Quebec, Chrétien is a law graduate from Uni ...

. During the

1993 Canadian federal election The 1993 Canadian federal election was held on October 25, 1993, to elect members to the House of Commons of the 35th Parliament of Canada. Considered to be a major political realignment, it was one of the most eventful elections in Canada's hist ...

, Chrétien's first as leader of the

Liberal Party of Canada The Liberal Party of Canada (french: Parti libéral du Canada, region=CA) is a federal political party in Canada. The party espouses the principles of liberalism,McCall, Christina; Stephen Clarkson"Liberal Party". ''The Canadian Encyclopedia'' ...

, the opposition

Progressive Conservative Party of Canada The Progressive Conservative Party of Canada (PC; french: Parti progressiste-conservateur du Canada) was a centre-right federal political party in Canada that existed from 1942 to 2003. From Canadian Confederation in 1867 until 1942, the ...

ran an attack ad in which voice actors criticized him over images that seemed to highlight his abnormal facial expressions. The ad was interpreted as an attack on Chrétien's physical appearance and garnered widespread anger among the public, while Chrétien used the ad to make himself more sympathetic to voters. The ad had the adverse effect of increasing Chrétien's lead in the polls and the subsequent backlash clinched the election for the Liberals, which the party won in a landslide.

References

External links

* {{DEFAULTSORT:Bell's Palsy Ailments of unknown cause Facial nerve disorders Otorhinolaryngology Wikipedia neurology articles ready to translate Wikipedia medicine articles ready to translate