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There are twelve cranial nerves that lead directly from the brain to various parts of the head. These nerves process hearing, assist in maintaining equilibrium, control movements of the face, throat, neck and eyes, receive sensations from the face, throat and tongue, control the nerve of smell and control the nerve of sight. Any disorder of these nerves will produce a loss of function in the area that the nerve affects. Such is the case with Bell's palsy which is caused by a abnormality of the facial nerve. Named for Scottish anatomist Sir Charles Bell who was first to distinguish between motor and sensory functions of the nerves, Bell's palsy is a paralysis of the facial muscles that usually affects only one side of the face.
Although the cause of Bell's palsy is unknown, it is believed that it may be associated with herpes zoster or shingles, a swelling of the facial nerve as a reaction to viral infections or a lack of blood supply. This disorder affects the cranial nerve that stimulates action in the facial muscles creating a temporary inflammation of the facial nerve. This is a common disorder that appears suddenly, even though the person affected may develop a pain behind the ear or weakness in the facial muscles prior to the onset. The symptoms that occur are unpredictable and can range from mild to the complete paralysis of one side of the face. Unlike a stroke which also causes facial paralysis in the lower part of the face, Bell's palsy affects only the face in both the upper and lower areas.
When this disorder occurs the symptoms may include a droop of the eyelid and corner of the mouth on one side of the face. Pain in the ear on the affected side is not uncommon. Wrinkling the brow or closing the eye may become impossible and smiling may become distorted. If certain branches of the nerve are affected sounds may sound unnaturally loud or taste may become impaired. The side of the face that is paralyzed may become flat and expressionless. The person experiencing the symptoms will often feel as though their face is twisted. Many people experience a numbness or heavy feeling in the area that is affected even though the sensations in the face are actually normal. In very rare cases of Bell's palsy there may be interference with the production of saliva or the ability to produce tears.
There are many causes of facial nerve paralysis but most appear much more slowly than Bell's palsy. Some of these include the destruction of a facial nerve by a viral infection, infections of the middle ear, infections of the mastoid sinuses, Lyme disease and fractures of a bones at the base of the skull. In most cases a doctor will eliminate other disorders by taking a personal history and running test like x-ray, CT scan or MRI scans.
If any doubt exist after these test a blood test may be run to check for Lyme disease. Treatment of Bell's palsy may include the use of corticosteroid drugs or ACTH to reduce the inflammation of the nerve. Analgesics may be prescribed to relieve any pain in the ear. When the paralyzed muscles prevent the eye from closing completely eye drops may be prescribed to lubricate the eye and an eye patch may be prescribed for bed time to protect the eye from corneal abrasions. With severe paralysis it may be suggested to massage the facial muscles. If the paralysis persist surgery may be needed.
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