Bell’s Palsy

The most common condition resulting in facial nerve weakness or paralysis is Bell’s palsy, named after Sir Charles Bell who first described the condition. The underlying cause of Bell’s palsy is not known, but it may well be due to an infection or inflammation of the nerve. We know that the nerve swells in its tight bony canal. This swelling results in pressure on the nerve fibers and their blood vessels. Treatment is directed at decreasing the swelling and restoring the circulation so that the nerve fibers may again function normally.

Herpes Zoster Oticus

A condition similar to Bell’s palsy is herpes Zoster Oticus or "shingles" of the facial nerve. In this condition, there is not only facial weakness but also often hearing loss, unsteadiness, and painful ear blisters. These additional symptoms usually subside spontaneously but some hearing loss and discomfort may remain.

Injuries of the Facial Nerve

The most common cause of facial nerve injury is due to a skull fracture. This injury may occur immediately or may develop some days later due to nerve swelling.

Injury to the facial nerve may occur in the course of operations on the ear. This complication, fortunately, is very uncommon. It may occur, however, when the nerve is not in its normal anatomical position (congenital abnormality) or when the nerve is so distorted by mastoid or middle ear disease that it is not identifiable. In rare cases it may be necessary to remove a portion of the nerve in order to eradicate the disease.

Delayed weakness or paralysis of the face following reconstructive middle ear surgery (myringoplasty, tympanoplasty, stapedectomy) is uncommon, but occurs at times due to swelling of the nerve during the healing period. Fortunately, this type of facial nerve weakness usually subsides spontaneously in several weeks and rarely requires further surgery.

Tumors

Acoustic Tumors: The most common tumor to involve the facial nerve is a nonmalignant fibroid tumor of the hearing and balance nerve called an acoustic neuroma. Although there is rarely any weakness of the face before surgery, tumor removal sometimes results in weakness or paralysis due to the close proximity of the facial nerve. This weakness usually subsides in several months without treatment.

Facial Nerve Neuroma: A nonmalignant fibroid growth may grow in the facial nerve itself, producing a gradually progressive facial nerve paralysis.

It may be necessary to server or remove a portion of the facial nerve in order to remove an acoustic tumor or a facial nerve neuroma. An attempt is made to sew the nerve ends together at the time of surgery or to insert a nerve graft. The nerve used in grafting is taken from a skin sensation nerve in the neck. Total paralysis will be present until the nerve regrows through the graft, usually a period of 6 to 24 months. At time, a nerve procedure is necessary later, connecting a tongue nerve to the facial nerve (hypoglossal-facial anastomosis). In all of these situations there will be some permanent facial weakness.

Removal of a facial nerve neuroma may necessitate removal of the inner ear structures. If this is necessary, it results in a total loss of hearing in the operated ear and temporary severe dizziness. Persistent unsteadiness is uncommon.

Infection

Acute or chronic middle ear or mastoid ear infections occasionally cause a weakness of the face due to swelling or direct pressure on the nerve. In acute infections, the weakness usually subsides as the infection is controlled and the swelling around the nerve subsides.

Facial nerve weakness occurring in chronically infected ears is usually due to pressure from a cholesteatoma (skin-lined cyst). Mastoid surgery is performed to eradicate the infection and relieve nerve pressure. Some permanent facial weakness may remain.

Brain Disease

Tumors and circulatory disturbances of the nervous system may cause facial nerve paralysis. The most common example of this is a stroke. As opposed to other conditions listed here, in brain diseases there are usually many other symptoms, which indicated the cause of the problem. Treatment is managed by the neurotologist in conjunction with an internist, neurologist, or neurosurgeon.

Hemifacial Spasm

Hemifacial spasm is an uncommon disease which results in spasmotic contractions of one side of the face. Extensive investigation is necessary at times to establish the diagnosis correctly. In some cases, a hemifacial spasm is caused by an irritation of the facial nerve by a blood vessel near the brain. Examination of the nerve and correction of the irritation, if present, is possible by a surgical approach.