Bell's Palsy



Bell's palsy is a form of temporary facial paralysis resulting from damage or trauma to a cranial nerve that controls movement in the face. It is the most common cause of facial paralysis. Bell's palsy often causes significant facial distortion. The left and right sides of the face are affected at approximately equal rates. It is rare to have paralysis on both sides of the face but this does occur.

Other Names

 * Facial palsy
 * Idiopathic peripheral facial palsy

Signs and Symptoms

 * Drooling
 * Droopy eyelid
 * Drooping corners of the mouth
 * Dry eyes
 * Dry mouth
 * Facial paralysis of one side of the face
 * Loss of sense of taste
 * Pain behind or in front of the ear
 * Sensitivity to sound on the affected side of the face

Causes


The nerve that is injured in Bell's palsy is the 7th cranial nerve (CN VII) also called the facial nerve.

The nerve originates in an area of the brain stem known as the pons, then divides into its main branches inside the parotid gland. The parotid glands are located within each cheeck, close to the ear. They function to secrete saliva and are in fact, the largest salivary glands.

The branches of the facial nerve divide into several thousand smaller nerve fibers that reach into the face, neck, salivary glands and the outer ear. The nerve controls the muscles of the neck, the forehead and facial expressions, as well as sound volume. It also stimulates secretions of the lower jaw, the tear glands and the salivary glands in the front of the mouth. Taste sensations at the front two-thirds of the tongue and sensations at the outer ear are transmitted by the 7th nerve.

Most scientists believe that a viral infection such as viral meningitis or the herpes simplex virus causes Bell's palsy when the facial nerve swells and becomes inflamed in reaction to the infection. Other diseases that have been linked to Bell's palsy include: Lyme disease, Diabetes, Sarcoidosis.

History and Physical Examination
Doctors usually diagnose Bell's palsy by ruling out other possible causes.
 * A history is taken and a thorough examination of the head and neck is performed.
 * If there is any decreased range of movement on one side of the face (such as not being able to close both eyes), it usually means that one side of the face is weaker than the other.
 * If only part of the face is affected, the condition is not Bell palsy. If, for example, the mouth area is weak but the forehead moves, Bell's palsy is ruled out.

Tests

 * Imaging tests such as Computed tomography (CT) scan or Magnetic resonance imaging (MRI) are used to detect tumor, infection, fractures of the bones of the face, or other problems with the facial nerve.
 * Tests of hearing and balance may be used to determine if the nerve responsible for hearing is also damaged and to assess injury to the inner ear.
 * Tests can be performed to evaluate the eye's ability to produce tears. The sense of taste also can be evaluated to determine the location and severity of a facial nerve lesion.
 * Electromyography (EMG) can determine if there is any damage to the facial nerve.
 * A Nerve Conduction Test may also be done to evaluate damage to the nerve
 * Laboratory tests be performed to determine the underlying cause (glucose for diabetes, herpes simplex titers, lyme titers)

Treatment
There is no cure or standard course of treatment for Bell's palsy. The most important factor in treatment is to eliminate the source of the nerve damage. Some cases are mild and do not require treatment since the symptoms usually subside on their own within two weeks. For others, treatment may include:

Medications
Some medications that may be used for Bell's palsy include:
 * Acyclovir, used to fight viral infections like the herpes simplex virus (HSV)
 * Prednisone, a steroid used to reduce inflammation and swelling
 * Aspirin for pain relief
 * Acetaminophen for pain relief
 * Ibuprofen for pain relief and inflammation

Because of possible drug interactions, the use of any over-the-counter medicines should be discussed with a heaalth care provider.

Therapies
An eye patch and/or eye drops may be required to keep the eye(s) protected and lubricated.

Surgery
Decompression surgery for Bell's palsy, used to relieve pressure on the nerve, is controversial and seldom recommended.

Holistic and alternative treatments
The use of acupuncture and moxibustion (a traditional herbal medicine which is ground and used with acupuncture needles or burned into the skin) has been shown in clincical studies to be an effective treatment for Bell's palsy.

Complications
The following complications are possible:


 * Corneal ulcerations and infections due to inability to close the eyelid properly
 * Facial disfigurement
 * Chronic taste disturbances
 * Chronic spasms of the face or eyelids

Recurrence of Bell's palsy may also occur. The possibility of recurrence had been thought to be as high as 10 - 20%. These figures have been lowered as more has been learned about conditions that are now diagnosed as other types of facial palsies. The average timespan between recurrences is 10 years.

Clinical Trials
Bell Palsy clinical trials

Recent discoveries
Several recently completed studies have shown a benefit to the treatment of Bell's palsy with valacyclovir and prednisolone therapy rather than placebo or prednisolone alone. The study first excluded zoster sine herpete (herpes zoster infection without rash) from the diagnosis of Bell's palsy.

Future research
A recent study examined whether facial exercises and biofeedback are an effective treatment for Bell's palsy. The trial size was small so further research is needed.

Bell's palsy has been reported as occurring after immunization. An international work group has been formed to study the consistency of diagnosis of Bell's palsy and to determine whether it can be defined as an adverse event following immunization (AEFI).

Expected Outcome
The outcome for individuals with Bell's palsy is generally very good. The extent of nerve damage determines the extent of recovery. With or without treatment, About 60 - 80% of cases go away completely within a few weeks to months. Sometimes the condition results in permanent changes. The disorder is not life threatening.

History
The condition is named for Sir Charles Bell (1774-1842), a Scottish anatomist, physiologist, neurologist, artist and surgeon who discovered the distinct functions of the motor and sensory nerves in 1811. In 1821, Bell described the long thoracic nerve, which supplies the serratus anterior muscle, and which now bears his name. In the same paper he showed that lesions of the seventh cranial nerve produce facial paralysis (now termed Bell palsy).

Prevalence
The annual incidence of Bell's palsy is about 20 people in 100,000. The incidence increases with age. Bell's palsy occurs equally in males and females. It also occurs approximately equally across most races. Those at high risk include pregnant women and people with diabetes mellitus. About 10% of those with Bell's palsy have a family history of the condition.