Bell’s Palsy

Other Name: Facial Palsy

Definition:
Bell’s palsy is a paralysis of the facial nerve resulting in inability to control facial muscles on the affected side. Several conditions can cause a facial paralysis, e.g., brain tumor, stroke, and Lyme disease. However, if no specific cause can be identified, the condition is known as Bell’s Palsy. Named after Scottish anatomist Charles Bell, who first described it, Bell’s palsy is the most common acute mononeuropathy (disease involving only one nerve), and is the most common cause of acute facial nerve paralysis.

Bell’s palsy is defined as an idiopathic unilateral facial nerve paralysis, usually self-limiting. The trademark is rapid onset of partial or complete palsy, usually in a single day.

It is thought that an inflammatory condition leads to swelling of the facial nerve (nervus facialis). The nerve travels through the skull in a narrow bone canal beneath the ear. Nerve swelling and compression in the narrow bone canal are thought to lead to nerve inhibition, damage or death. No readily identifiable cause for Bell’s palsy has been found, but clinical and experimental evidence suggests herpes simplex type 1 infection may play a role.

Doctors may prescribe anti-inflammatory and anti-viral drugs. Early treatment is necessary for the drug therapy to have effect. The effect of treatment is still controversial. Most people recover spontaneously and achieve near-normal functions. Many show signs of improvement as early as 10 days after the onset, even without treatment.

Often the eye in the affected side cannot be closed. The eye must be protected from drying up, or the cornea may be permanently damaged resulting in impaired vision.

For many people, the first guess would be a stroke. But if your muscle weakness or paralysis affects only your face, a more likely cause is Bell’s palsy.

Each year, about 40,000 Americans develop Bell’s palsy, a condition that occurs when the nerve that controls the facial muscles becomes swollen or compressed. The problem can occur at any age, but rarely affects people under the age of 15 or over the age of 60.

For most people, Bell’s palsy symptoms begin to improve within a few weeks, with complete recovery within three to six months. Between 8 percent and 10 percent will experience a recurrence of the signs and symptoms, sometimes on the opposite side of the face. And a small number of people never recover and continue to have some signs and symptoms for life.

Investigation:
Bell’s palsy (or facial palsy) is characterized by facial drooping on the affected half, due to malfunction of the facial nerve (VII cranial nerve), which controls the muscles of the face. Facial palsy is typified by inability to control movement in the facial muscles. The paralysis is of the infranuclear/lower motor neuron type.

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Click to learn more about Bell’s Polsy ( Facial nerve & how it works etc.)

The facial nerves control a number of functions, such as blinking and closing the eyes, smiling, frowning, lacrimation, and salivation. They also innervate the stapedial (stapes) muscles of the middle ear and carry taste sensations from the anterior two thirds of the tongue.

Clinicians should determine whether all branches of the facial nerve are involved, or whether the forehead muscles are spared. Since forehead muscles receive innervation from both sides of the brain, the forehead can still be wrinkled by a patient whose facial palsy is caused by a problem in the brain (central facial palsy) but not if the problems resides in the facial nerve itself (peripheral palsy).

One disease that may be difficult to exclude in the differential diagnosis is involvement of the facial nerve in infections with the herpes zoster virus. The major differences in this condition are the presence of small blisters, or vesicles, of the external ear and hearing disturbances, but these findings may occasionally be lacking (zoster sine herpete).

Lyme disease may produce the typical palsy, and may be easily diagnosed by looking for Lyme-specific antibodies in the blood. In endemic areas Lyme disease may be the most common cause of facial palsy.
Signs and symptoms:

Signs and symptoms of Bell’s palsy may include:

*Sudden onset of paralysis or weakness on one side of your face, making it difficult to smile or close your eye on the affected side

*Facial droop and difficulty with facial expressions

*Pain behind or in front of your ear on the affected side

*Sounds that seem louder on the affected side

*Pain, usually in the ear on the affected side

*Headache

*Loss of taste

*Changes in the amount of tears and saliva your body produces

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Other symptoms are:
Although defined as a mononeuritis (involving only one nerve), patients 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”. This is yet an enigmatic facet of this condition.

Causes:
It is thought that as a result of inflammation of the facial nerve, pressure is produced on the nerve where it exits the skull within its bony canal, 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 include tumor, meningitis, stroke, diabetes mellitus, head trauma and inflammatory diseases of the cranial nerves (sarcoidosis, brucellosis, etc.). In these conditions, the neurologic findings are rarely restricted to the facial nerve. Babies can be born with facial palsy, and they exhibit many of the same symptoms as people with Bell’s palsy; this is often due to a traumatic birth which causes irreparable damage to the facial nerve, i.e. acute facial nerve paralysis.

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In some research the herpes simplex virus type 1 (HSV-1) was identified in a majority of cases diagnosed as Bell’s palsy. This has given hope for anti-inflammatory and anti-viral drug therapy (prednisone and acyclovir). Other research[3] however, identifies HSV-1 in only 31 cases (18 percent), herpes zoster (zoster sine herpete) in 45 cases (26 percent) in a total of 176 cases clinically diagnosed as Bell’s Palsy,. That infection with herpes simplex virus should play a major role in cases diagnosed as Bell’s palsy therefore remains a hypothesis that requires further research.

The herpes simplex virus type 1 (HSV-1) infection is associated with demyelination of nerves. This nerve damage mechanism is different from the above mentioned – that oedema, 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 system response. The quote below captures this hypothesis and the implication for other types of treatment:

It is also possible that HSV-1 replication itself is not responsible for the damage to the facial nerves and that inhibition of HSV-1 replication by acyclovir does not prevent the progression of nerve dysfunction. Because the demyelination of facial nerves caused by HSV-1 reactivation, via an unknown immune response, is implicated in the pathogenesis of HSV-1-induced facial palsy, a new strategy of treatment to inhibit such an immune reaction may be effective.

Virus reactivation
Some viruses are thought to establish a persistent (or latent) infection without symptoms, e.g. Epstein-Barr virus of the herpes family. Reactivation of an existing (dormant) viral infection has been suggested as cause behind the acute Bell’s palsy. Studies suggest that this new activation could be preceded by trauma, environmental factors, and metabolic or emotional disorders, thus suggesting that stress – emotional stress, environmental stress (e.g. cold), physical stress (e.g. trauma) – in short, a host of different conditions, may trigger reactivation.

Smile with Bell’s palsy..

The most common cause of Bell’s palsy appears to be the herpes simplex virus, which also causes cold sores and genital herpes. Other viruses that have been linked to Bell’s palsy include the virus that causes chickenpox and shingles (herpes zoster), the virus that causes mononucleosis (Epstein-Barr), and another virus in the same family (cytomegalovirus).

Diagnosis:
There is no specific laboratory test to confirm a diagnosis of Bell’s palsy. Your doctor may be able to make a preliminary diagnosis of Bell’s palsy by looking at your face and asking you to try to move your facial muscles.

Other conditions — such as a stroke, infections and tumors — also may cause facial muscle weakness, mimicking Bell’s palsy. If after a few days there’s still doubt about the diagnosis, your doctor may recommend other tests:

Electromyography (EMG). This test can confirm the presence of nerve damage and determine its severity. An EMG measures the electrical activity of a muscle in response to stimulation and the nature and speed of the conduction of electrical impulses along a nerve.
Imaging scans. An X-ray, magnetic resonance imaging (MRI) or computerized tomography (CT) may be needed on occasion to eliminate other possible sources of pressure on the facial nerve, such as an infection, tumor or skull fracture.

Bell’s palsy is a diagnosis of exclusion; by elimination of other reasonable possibilities. Therefore, by definition, no specific cause can be ascertained. Bell’s palsy is commonly referred to as idiopathic or cryptogenic, meaning that it is due to unknown causes. Being a residual diagnostic category, the Bell’s Palsy diagnosis likely spans different conditions which our current level of medical knowledge cannot distinguish. This may inject fundamental uncertainty into the discussion below of etiology, treatment options, recovery patterns etc. See also the section below on Other symptoms. Studies[1] show that a large number of patients (45%) 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. A significant number of cases are misdiagnosed (ibid.). This is unsurprising from a diagnosis of exclusion, which depends on a thorough investigation.

Treatment:
Most people with Bell’s palsy recover fully — with or without treatment. But your doctor may suggest medications or physical therapy to help speed your recovery. Surgery is rarely an option for Bell’s palsy.

Treatment is a matter of controversy. In patients presenting with incomplete facial palsy, where the prognosis for recovery is very good, treatment may be unnecessary. However, patients presenting with complete paralysis, marked by an inability to close the eyes and mouth on the involved side, are usually treated with anti-inflammatory corticosteroids. Prednisolone, a corticosteroid, if used early in treatment of Bell’s palsy, significantly improves the chances of complete recovery at 3 and 9 months when compared to treatment with acyclovir, an anti-viral drug, or no treatment at all. The likely association of Bell’s palsy with the herpes virus has led most American neurologists to prescribe a course of anti-viral medication (such as acyclovir) to all patients with unexplained facial palsy, although a large study showed no additional benefit from acyclovir beyond that from prednisolone alone. Surgical procedures to decompress the facial nerve have been attempted, but have not been proven beneficial. Acupuncture has also been studied, with inconclusive results.

A practice parameter from the American Academy of Neurology states that “corticosteroids are safe and probably effective, and that acyclovir is safe and possibly effective”. Early treatment (ie, within 3 days after the onset) is necessary for acyclovir-prednisone therapy to be effective. If the patient presents 10 days after the onset of symptoms, no drug treatment is necessary. (ibid.)

Medications:
Study results have been mixed regarding the effectiveness of two types of drugs commonly used to treat Bell’s palsy — corticosteroids and antiviral medications.

Corticosteroids, such as prednisone, are powerful anti-inflammatory agents. If they can reduce the swelling of the facial nerve, it will fit more comfortably within the bony corridor that surrounds it. If Bell’s palsy is triggered by a virus, then an antiviral drug — such as acyclovir or valacyclovir — may stop the progression of the viral infection.

Some clinical studies show benefit from early treatment with corticosteroids, antivirals or a combination of both types of drugs. Other studies do not. Evidence of the effectiveness of corticosteroids appears to be stronger than that for antiviral drugs.

Physical therapy :
Paralyzed muscles can shrink and shorten, causing permanent contractures. Massaging and exercising your facial muscles may help prevent this from occurring. Moist heat may help relieve pain.

Alternative medication:

Some people with Bell’s palsy may benefit from:

*Relaxation techniques
*Acupuncture
*Biofeedback training
*Vitamin therapy — specifically B-12, B-6 and zinc
*In traditional Chinese medicine, Bell’s palsy is attributed to a “wind cold” attack brought about by exposure to wind.

Recovery:
Even without any treatment, Bell’s palsy tends to carry a good prognosis. In a study 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 1 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 finds 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 sequelae. 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.

Self-care:
If you can’t close your eye, you’ll need to keep the eye moist with hourly eyedrops during the day and an eye ointment at night. If the clear protective covering of the eye — called the cornea — becomes too dry, it can cause permanent vision loss. Your doctor may want you to wear glasses or goggles during the day and an eye patch at night to protect your eye from getting poked or scratched.

Complications:
Major complications of the condition are chronic loss of taste (ageusia), chronic facial spasm and corneal infections. To prevent the latter, the eyes may be protected by covers, or taped shut during sleep and for rest periods, and tear-like eye drops or eye ointments may be recommended, especially for cases with complete paralysis. Where the eye does not close completely, the reflex is also affected; great care should be taken to protect the eye from injury.

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 which 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. 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.

In addition, around 6% of patients exhibit crocodile tear syndrome on recovery, where they will shed 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.

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Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://en.wikipedia.org/wiki/Bell’s_palsy
http://www.mayoclinic.com/health/bells-palsy/

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