Bell's palsy

Alternative names:

facial palsy

Definition:

A disorder involving sudden facial drooping and decreased ability to move the face. It is caused by damage to cranial nerve VII.

Causes, incidence, and risk factors:

Bell's palsy is an acute form of cranial mononeuropathy VII and is the most common form of this type of nerve damage (peripheral neuropathy). Statistics indicate that the disorder affects approximately 2 out of 10,000 people, however, the actual incidence is likely to be much higher (around 1 out of 500 to 1,000). The disorder is a mononeuropathy (involvement of a single nerve) that damages the 7th cranial (facial) nerve, the nerve that controls movement of the muscles of the face. The cause is unknown. In some cases, the disorder is presumed to be associated with inflammation of the facial nerve where it travels through the bones of the skull. It may also be caused by head injury, tumor, hypertension, or infarction.