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Facial nerve paralysis is a common problem that involves the paralysis of any structures innervated by the
facial nerve 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 ta ...
. The pathway of the facial nerve is long and relatively convoluted, so there are a number of causes that may result in facial nerve paralysis. The most common is
Bell's palsy 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. In most cases, the weakness is temporary and significantly improves over weeks. Symptoms can vary f ...
, a disease of unknown cause that may only be diagnosed by exclusion of identifiable serious causes.


Signs and symptoms

Facial nerve paralysis is characterised by facial weakness, usually only in one side of the face, with other symptoms possibly including loss of taste, hyperacusis and decreased salivation and tear secretion. Other signs may be linked to the cause of the paralysis, such as
vesicle Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry), a supramolecular assembly of lipid molecules, like a cell membrane * Synaptic vesicle ; In human embryology * Vesicle (embryology), bulge-like features o ...
s in the ear, which may occur if the facial palsy is due to
shingles 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. ...
. Symptoms may develop over several hours. Acute facial pain radiating from the ear may precede the onset of other symptoms.


Causes


Bell's palsy

Bell's palsy is the most common cause of acute facial nerve paralysis. There is no known cause of Bell's palsy, although it has been associated with
herpes simplex Herpes simplex is a viral infection caused by the herpes simplex virus. Infections are categorized based on the part of the body infected. Oral herpes involves the face or mouth. It may result in small blisters in groups often called cold ...
infection. Bell's palsy may develop over several days, and may last several months, in the majority of cases recovering spontaneously. It is typically diagnosed clinically, in patients with no risk factors for other causes, without vesicles in the ear, and with no other neurological signs. Recovery may be delayed in the elderly, or those with a complete paralysis. Bell's palsy is often treated with
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 invo ...
s.


Infection

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 mig ...
, an infection caused by
Borrelia burgdorferi ''Borrelia burgdorferi'' is a bacterial species of the spirochete class in the genus ''Borrelia'', and is one of the causative agents of Lyme disease in humans. Along with a few similar genospecies, some of which also cause Lyme disease, it make ...
bacteria and spread by ticks, can account for about 25% of cases of facial palsy in areas where Lyme disease is common. 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 o ...
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 Michi ...
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 ...
, but it is expanding into other areas. 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. Lyme disease is treated with antibiotics. Reactivation of
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. ...
virus, as well as being associated with Bell's palsy, may also be a direct cause of facial nerve palsy. Reactivation of latent virus within the
geniculate ganglion The geniculate ganglion (from Latin ''genu'', for "knee") is a collection of pseudounipolar sensory neurons of the facial nerve located in the facial canal of the head. It receives fibers from the facial nerve. It sends fibers that supply the la ...
is associated with vesicles affecting the ear canal, and termed
Ramsay Hunt syndrome type II Inflammation of the geniculate ganglion of the facial nerve is a late consequence of '' varicella zoster'' virus (VZV) known as Ramsay Hunt syndrome (RHS), commonly known as herpes zoster oticus. In regards with the frequency, less than 1% of var ...
. In addition to facial paralysis, symptoms may include ear pain and vesicles,
sensorineural hearing loss Sensorineural hearing loss (SNHL) is a type of hearing loss in which the root cause lies in the inner ear or sensory organ (cochlea and associated structures) or the vestibulocochlear nerve (Cranial nerves, cranial nerve VIII). SNHL accounts for ...
, and
vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...
. Management includes
antiviral drug Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do ...
s and oral
steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...
s.
Otitis media Otitis media is a group of inflammatory diseases of the middle ear. One of the two main types is acute otitis media (AOM), an infection of rapid onset that usually presents with ear pain. In young children this may result in pulling at the ear, ...
is an infection in the middle ear, which can spread to the facial nerve and inflame it, causing compression of the nerve in its canal.
Antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
s are used to control the otitis media, and other options include a wide
myringotomy A myringotomy is a surgical procedure in which an incision is created in the eardrum (tympanic membrane) to relieve pressure caused by excessive buildup of fluid, or to drain pus from the middle ear. A tympanostomy tube may be inserted through t ...
(an incision in the
tympanic membrane In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the ai ...
) or decompression if the patient does not improve. Chronic otitis media usually presents in an ear with chronic discharge ( otorrhea), or hearing loss, with or without ear pain (
otalgia Ear pain, also known as earache or otalgia, is pain in the ear. Primary ear pain is pain that originates from the ear. Secondary ear pain is a type of referred pain, meaning that the source of the pain differs from the location where the pain is ...
). Once suspected, there should be immediate surgical exploration to determine if a
cholesteatoma Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of the ...
has formed as this must be removed if present. Inflammation from the middle ear can spread to the canalis facialis of the temporal bone - through this canal travels the facial nerve together with the statoacoustisus nerve. In the case of inflammation the nerve is exposed to edema and subsequent high pressure, resulting in a periferic type palsy.


Trauma

In
blunt trauma Blunt trauma, also known as blunt force trauma or non-penetrating trauma, is physical traumas, and particularly in the elderly who fall. It is contrasted with penetrating trauma which occurs when an object pierces the skin and enters a tissue ...
, the facial nerve is the most commonly injured
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 f ...
.
Physical trauma An injury is any physiological damage to living tissue caused by immediate physical stress. An injury can occur intentionally or unintentionally and may be caused by blunt trauma, penetrating trauma, burning, toxic exposure, asphyxiation, or ...
, especially
fracture Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displ ...
s of the
temporal bone The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. T ...
, may also cause acute facial nerve paralysis. Understandably, the likelihood of facial paralysis after trauma depends on the location of the trauma. Most commonly, facial paralysis follows temporal bone fractures, though the likelihood depends on the type of fracture. ''Transverse fractures'' in the horizontal plane present the highest likelihood of facial paralysis (40-50%). Patients may also present with blood behind the tympanic membrane, sensory deafness, and
vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...
; the latter two symptoms due to damage to
vestibulocochlear nerve The vestibulocochlear nerve or auditory vestibular nerve, also known as the eighth cranial nerve, cranial nerve VIII, or simply CN VIII, is a cranial nerve that transmits sound and equilibrium (balance) information from the inner ear to the bra ...
and the inner ear. ''Longitudinal fracture'' in the vertical plane present a lower likelihood of paralysis (20%). Patients may present with blood coming out of the
external auditory meatus The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the pinna to the eardrum and is about in length and in diameter. Struct ...
),
tympanic membrane In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the ai ...
tear, fracture of
external auditory canal The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the pinna to the eardrum and is about in length and in diameter. Struct ...
, and
conductive hearing loss Conductive hearing loss (CHL) occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). If a conductive hearing loss occurs in conjunction wi ...
. In patients with mild injuries, management is the same as with Bell's palsy – protect 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 con ...
s and wait. In patients with severe injury, progress is followed with nerve conduction studies. If nerve conduction studies show a large (>90%) change in nerve conduction, the nerve should be decompressed. The facial paralysis can follow immediately the trauma due to direct damage to the facial nerve, in such cases a surgical treatment may be attempted. In other cases the facial paralysis can occur a long time after the trauma due to oedema and inflammation. In those cases steroids can be a good help.


Tumors

A
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 ...
compressing the facial nerve anywhere along its complex pathway can result in facial paralysis. Common culprits are facial neuromas, congenital
cholesteatoma Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of the ...
s,
hemangioma A hemangioma or haemangioma is a usually benign vascular tumor derived from blood vessel cell types. The most common form, seen in infants, is an infantile hemangioma, known colloquially as a "strawberry mark", most commonly presenting on the s ...
s, acoustic neuromas, parotid gland
neoplasm 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 ...
s, or metastases of other tumours. Often, since facial neoplasms have such an intimate relationship with the facial nerve, removing tumors in this region becomes perplexing as the physician is unsure how to manage the tumor without causing even more palsy. Typically, benign tumors should be removed in a fashion that preserves the facial nerve, while malignant tumors should always be resected along with large areas of tissue around them, including the facial nerve. While this will inevitably lead to facial paralysis, safe removal of a malignant neoplasm is vital for patient survival. After tumor removal, the facial nerve can be reinnervated with techniques such as cross-facial nerve grafting, nerve transfers and end-to-end nerve repair. Alternative treatment methods include muscle transfer techniques, such as the gracilis free muscle transfer or static procedures. Patients with facial nerve paralysis resulting from tumours usually present with a progressive, twitching paralysis, other neurological signs, or a recurrent Bell's palsy-type presentation. The latter should always be suspicious, as Bell's palsy should not recur. A chronically discharging ear must be treated as a cholesteatoma until proven otherwise; hence, there must be immediate
surgical Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...
exploration. Computed tomography (CT) or magnetic resonance (MR) imaging should be used to identify the location of the tumour, and it should be managed accordingly. Other neoplastic causes include leptomeningeal carcinomatosis.


Stroke

Central facial palsy Central facial palsy (colloquially referred to as central seven) is a symptom or finding characterized by paralysis or paresis of the lower half of one side of the face. It usually results from damage to upper motor neurons of the facial nerve. ...
can be caused by a lacunar infarct affecting fibers in the
internal capsule The internal capsule is a white matter structure situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the ...
going to the nucleus. The
facial nucleus The facial motor nucleus is a collection of neurons in the brainstem that belong to the facial nerve (cranial nerve VII). These lower motor neurons innervate the muscles of facial expression and the stapedius. Structure The nucleus is situated i ...
itself can be affected by infarcts of the pontine arteries. Unlike peripheral facial palsy, central facial palsy does not affect the forehead, because the forehead is served by nerves coming from both motor cortexes.


Other

Other causes may include: *
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 ...
* Facial nerve paralysis, sometimes bilateral, is a common manifestation of sarcoidosis of the nervous system,
neurosarcoidosis Neurosarcoidosis (sometimes shortened to neurosarcoid) refers to a type of sarcoidosis, a condition of unknown cause featuring granulomas in various tissues, in this type involving the central nervous system (brain and spinal cord). Neurosarcoidosi ...
. * Bilateral facial nerve paralysis may occur in
Guillain–Barré syndrome Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system. Typically, both sides of the body are involved, and the initial symptoms are changes in sensation or pain often ...
, an
autoimmune In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an " autoimmune disease" ...
condition of the peripheral nervous system. * Moebius syndrome is a bilateral facial paralysis resulting from the underdevelopment of the VII cranial nerve (facial nerve), which is present at birth. The VI cranial nerve, which controls lateral eye movement, is also affected, so people with Moebius syndrome cannot form facial expression or move their eyes from side to side. Moebius syndrome is extremely rare, and its cause or causes are not known. * Facial piercings, namely eyebrow piercings or tongue piercings, can in very rare cases cause damage to the facial nerve.


Diagnosis

A
medical history The medical history, case history, or anamnesis (from Greek: ἀνά, ''aná'', "open", and μνήσις, ''mnesis'', "memory") of a patient is information gained by a physician by asking specific questions, either to the patient or to other pe ...
and
physical examination In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the patien ...
, including a
neurological examination A neurological examination is the assessment of sensory neuron and motor responses, especially reflexes, to determine whether the nervous system is impaired. This typically includes a physical examination and a review of the patient's medical hi ...
, are needed for diagnosis. The first step is to observe what parts of the face do not move normally when the person tries to smile, blink, or raise the eyebrows. If the forehead wrinkles normally, a diagnosis of
central facial palsy Central facial palsy (colloquially referred to as central seven) is a symptom or finding characterized by paralysis or paresis of the lower half of one side of the face. It usually results from damage to upper motor neurons of the facial nerve. ...
is made, and the person should be evaluated for
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 funct ...
. Otherwise, the diagnosis is peripheral facial palsy, and its cause needs to be identified, if possible. Ramsey Hunt's syndrome causes pain and small blisters in the ear on the same side as the palsy. Otitis media, trauma, or post-surgical complications may alternatively become apparent from history and physical examination. If there is a history of trauma, or a tumour is suspected, a CT scan or MRI may be used to clarify its impact. Blood tests or x-rays may be ordered depending on suspected causes. The likelihood that the facial palsy is caused by
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 mig ...
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. If the test is positive, the diagnosis is Lyme disease. If no cause is found, the diagnosis is Bell's Palsy.


Classification

Facial nerve paralysis may be divided into supranuclear and infranuclear lesions. In a clinical setting, other commonly used classifications include: intra-cranial and extra-cranial; acute, subacute and chronic duration.
The Plastics Fella Guide to Facial Nerve Anatomy


Supranuclear and nuclear lesions

Central facial palsy Central facial palsy (colloquially referred to as central seven) is a symptom or finding characterized by paralysis or paresis of the lower half of one side of the face. It usually results from damage to upper motor neurons of the facial nerve. ...
can be caused by a lacunar infarct affecting fibers in the
internal capsule The internal capsule is a white matter structure situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the ...
going to the nucleus. The
facial nucleus The facial motor nucleus is a collection of neurons in the brainstem that belong to the facial nerve (cranial nerve VII). These lower motor neurons innervate the muscles of facial expression and the stapedius. Structure The nucleus is situated i ...
itself can be affected by infarcts of the pontine arteries. These are corticobulbar fibers travelling in internal capsule.


Infranuclear lesions

Infranuclear lesions refer to the majority of causes of facial palsy.


Treatment

If an underlying cause has been found for the facial palsy, it should be treated. If it is estimated that the likelihood that the facial palsy is caused by
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 mig ...
exceeds 10%, empiric therapy 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 involv ...
, and reevaluated upon completion of laboratory tests for Lyme disease. All other patients should be treated with corticosteroids and, if the palsy is severe,
antivirals Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do no ...
. Facial palsy is considered severe if the person is unable to close the affected eye completely or the face is asymmetric even at rest. Corticosteroids initiated within three days of Bell's palsy onset have been found to increase chances of recovery, reduce time to recovery, and reduce residual symptoms in case of incomplete recovery. However, for facial palsy caused by Lyme disease, corticosteroids have been found in some studies to harm outcomes. Other studies have found antivirals to possibly improve outcomes relative to corticosteroids alone for severe Bell's palsy. In those whose blinking is disrupted by the facial palsy, frequent use of artificial tears while awake is recommended, along with ointment and a patch or taping the eye closed when sleeping. Several surgical treatment options exist to restore symmetry to the paralyzed face in patients where function does not return (see section Tumors above).


References


External links

{{DEFAULTSORT:Facial Nerve Paralysis Peripheral nervous system disorders Otorhinolaryngology Nerve paralysis