Muscle Diseases - Bell's palsy

Bell's palsy is a paralysis of the facial nerve that was first described by Sir Charles Bell, a Scottish surgeon of the early nineteenth century. It may affect men and women at any age, though it occurs most commonly between the ages of 30 and 50. The onset of the facial paralysis may be abrupt: the patient may awaken one morning unable to move one side of his face. He can't wrinkle one side of his forehead or raise the eyebrow; the eye will not close on the affected side, and when attempting to smile, the face is pulled to the opposite side. Occasionally the patient may experience discomfort about the ear on the involved side. There is no difficulty in swallowing, but because the muscles about the corner of the mouth are weak, drooling is not uncommon, and food may accumulate in the gutter between gum and lip.

Bell's palsy may affect the branch of the facial nerve that supplies taste sensation to the anterior part of the tongue and the branch that supplies a small muscle in the middle ear (the stapedius ) whose function it is to dampen loud sounds. Depending on the extent to which the facial nerve is affected, the patient may be unable to perceive taste on the side of the paralysis and may be unusually sensitive to sounds, a condition known as hyperacusis .

The most probable causes of Bell's palsy are inflammation of the facial nerve as it passes through a bony canal within the skull or inflammation of that bony canal with subsequent swelling and compression of the nerve. It is not uncommon that the patient has a history of exposure to a cold breeze, such as sleeping in a draft or riding in an open car. Any patient who has a facial weakness should be carefully evaluated by a physician, preferably a neurologist, to be quite certain that there is no other neurologic abnormality. When the diagnosis of Bell's palsy is certain, some therapeutic measures can be taken.

Treatment

There is no specific treatment for Bell's palsy, but many physicians recommend massage, application of heat, and exercise of the weak muscles, either passive (by external manipulation) or active (by use). These therapeutic measures do not specifically influence the course of the facial nerve paralysis, but they are thought to be useful in maintaining tone of the facial muscles and preventing permanent deformity. Occasionally a V-shaped adhesive tape splint can be applied to the affected side of the face, from the corner of the mouth to the temple. Some physicians treat the condition with steroids such as cortisone, which may hasten recovery if begun at the onset of the illness.

In treating Bell's palsy, it is important to remember that when the eyelid does not close normally, the conjunctiva and cornea are not fully lubricated, and corneal lesions may develop from excessive dryness or exposure to the air. For this reason, some ophthalmic lubrication may be recommended by the physician.

About 80 percent of the patients with Bell's palsy recover completely in a few days or weeks, and about 10 to 15 percent recover more slowly, over a period of three to six months. The remaining 5 to 10 percent will have some residual facial deformity.