Bell’s Palsy

Definition:-
Bell’s palsy or idiopathic facial paralys  is a dysfunction of cranial nerve VII (the facial nerve) that results 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.

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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 can occur bilaterally resulting in total facial paralysis in around 1% of cases.

It is thought that an inflammatory condition leads to swelling of the facial nerve. 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.

Corticosteroids have been found to improve outcomes while anti-viral drugs have not. Early treatment is necessary for steroids to be effective. Most people recover spontaneously and achieve near-normal to 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. In some cases denture wearers experience some discomfort.

Bell’s palsy occurs when the nerve that controls facial muscles on one side of your face becomes swollen or inflamed. As a result of Bell’s palsy, your face feels stiff. Half your face appears to droop, your smile is one-sided, and your eye resists closing.

Bell’s palsy can affect anyone, but rarely affects people under the age of 15 or over the age of 60.

For most people, Bell’s palsy symptoms improve within a few weeks, with complete recovery in three to six months. About 10 percent will experience a recurrence of Bell’s palsy, sometimes on the other side of the face. A small number of people continue to have some Bell’s palsy signs and symptoms for life.

Bell’s palsy occurs more often in people who:

*Are pregnant, especially during the third trimester, or who are in the first week after giving birth
*Have diabetes
*Have an upper respiratory infection, such as the flu or a cold

Also, some people who have recurrent attacks of Bell’s palsy, which is rare, have a family history of recurrent attacks. In those cases, there may be a genetic predisposition to Bell’s palsy.

Symptoms:
Bell’s 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.

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 the forehead muscles are spared. Due to an anatomical peculiarity, forehead muscles receive innervation from both sides of the brain. The forehead can therefore still be wrinkled by a patient whose facial palsy is caused by a problem in one of the hemispheres of the brain (central facial palsy). If the problem resides in the facial nerve itself (peripheral palsy) all nerve signals are lost on the ipsilateral (same side of the lesion) half side of the face, including to the forehead (contralateral forehead still wrinkles).

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, on 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.

The main symptom of Bell’s palsy is a sudden weakness or paralysis in one side of your face that causes it to droop. This may make it hard for you to close your eye on that side of your face.

Other symptoms include:

*Drooling.
*Eye problems, such as excessive tearing or a dry eye.
*Loss of ability to taste.
*Pain in or behind your ear.
*Numbness in the affected side of your face.
*Increased sensitivity to sound.
*Rapid onset of mild weakness to total paralysis on one side of your face — occurring within hours to days — making it difficult to smile or close your eye on the affected side
*Facial droop and difficulty making facial expressions
*Pain around the jaw or in or behind your ear on the affected side
*Increased sensitivity to sound on the affected side
*Headache
*Changes in the amount of tears and saliva you produce

In rare cases, Bell’s palsy can affect the nerves on both sides of your face.


Cause
:-
Some viruses are thought to establish a persistent (or latent) infection without symptoms, e.g. the Zoster virus of the face and Epstein-Barr viruses, both 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.

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)
*Another virus in the same family (cytomegalovirus)

With Bell’s palsy, the nerve that controls your facial muscles, which passes through a narrow corridor of bone on its way to your face, becomes inflamed and swollen — usually from a viral infection. Besides facial muscles, the nerve affects tears, saliva, taste and a small bone in the middle of your ear.

Pathology:
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. In a few cases, bilateral facial palsy has been associated with acute HIV infection.

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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[5] 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.

In addition, 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 also effective.

Diagnosis:-
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 that 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   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.

Risk Factors:
Although a mild case of Bell’s palsy normally disappears within a month, recovery from a case involving total paralysis varies. Complications may include:

*Irreversible damage to your facial nerve
*Misdirected regrowth of nerve fibers, resulting in involuntary contraction of certain muscles when you’re trying to move others (synkinesis) — for example, when you smile, the eye on the affected side may close
*Partial or complete blindness of the eye that won’t close, due to excessive dryness and scratching of the cornea, the clear protective covering of the eye.

Treatment:=
In patients presenting with incomplete facial palsy, where the prognosis for recovery is very good, treatment may be unnecessary. Patients presenting with complete paralysis, marked by an inability to close the eyes and mouth on the involved side, are usually treated. Early treatment (within 3 days after the onset) is necessary for therapy to be effective.[9] Steroids have been shown to be effective at improving recovery while antivirals have not.

Steroids
Corticosteroid such as prednisone significantly improves recovery at 6 months and are thus recommended.

Antivirals
Antivirals (such as acyclovir) are ineffective in improving recovery from Bell’s palsy beyond steroids alone. They were however commonly prescribed due to a theoretical link between Bell’s palsy and the herpes simplex and varicella zoster virus.

Physical therapy
Paralyzed muscles can shrink and shorten, causing permanent contractures. A physical therapist can teach you how to massage and exercise your facial muscles to help prevent this from occurring.

Surgery
One way to relieve the pressure on the facial nerve is to surgically open the bony passage through which it passes. This decompression surgery is controversial and rarely recommended. In some cases, however, plastic surgery may be needed to make your face look and work better.

Home Remedy  & Lyfe Style:
Home treatment may include:
*Protecting the eye you can’t close. Using lubricating eyedrops during the day and an eye ointment at night will help keep your eye moist. Wearing glasses or goggles during the day and an eye patch at night can protect your eye from getting poked or scratched.

*Taking over-the-counter pain relievers. Aspirin, ibuprofen (Advil, Motrin, others) or acetaminophen (Tylenol, others) may help ease your pain.

*Applying moist heat. Putting a washcloth soaked in warm water on your face several times a day may help relieve pain.

*Doing your physical therapy exercises. Massaging and exercising your face according to your physical therapist’s advice may help relax your facial muscles.

Alternative medicine:
Although there’s little scientific evidence to support the use of alternative medicine for people with Bell’s palsy, some people with the condition may benefit from the following:

*Relaxation techniques, such as meditation and yoga, may relieve muscle tension and chronic pain.

*Acupuncture, placing thin needles into your skin to relieve pain, may stimulate nerves and muscles, offering some relief.(The efficacy of acupuncture remains unknown because the available studies are of low quality (poor primary study design or inadequate reporting practices).

*Biofeedback training, by teaching you to use your thoughts to control your body, may help you gain better control over your facial muscles.

*Vitamin therapy — specifically B-12, B-6 and zinc — may help nerve growth

Prognosis:
Even without any treatment, Bell’s palsy tends to carry a good prognosis. 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 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 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 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.

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 blink reflex is also affected, and care must 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 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. 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%[citation needed] of patients exhibit crocodile tear syndrome, also called gustatolacrimal reflex or Bogorad’s 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. Gustatorial sweating can also occur.

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/DS00168
http://www.webmd.com/brain/tc/bells-palsy-treatment-overview

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