Cranial mononeuropathy VII is a mononeuropathy (damage to a single nerve) that involves the seventh cranial (facial) nerve, the nerve that controls movement of the muscles of the face.

This nerve, located in the skull, also contributes to sensation in the ear canal and the sense of taste. Isolated facial nerve damage may occur with localized lesions that put pressure on the facial nerve. This type of nerve damage may also be caused by systemic disorders such as HIV infection, sarcoidosis, Lyme disease. It may have no identifiable cause.

Bell's palsy is a disorder involving paralysis of the muscles innervated by the seventh cranial nerve, which is thought to be caused by an infection of the nerve by a herpesvirus.

• Face feels stiff
• Face feels pulled to one side
• Difficulty eating (items fall out of the weak corner of the mouth)
• Change in facial appearance
  • Facial droop
  • Difficulty with facial expressions, grimacing
  • Difficulty with fine facial movements
  • Paralysis of one side of the face
  • Difficulty closing one eye
• Impairment of taste
• Sensitivity to sound (hyperacusis)
• Headache
• Increased loudness of sound in one ear
• Pain behind the ear (for Bell's palsy)

An examination will show facial drooping that may be on one side of the face or isolated to the forehead, eyelid or mouth. Examination of the tympanic membrane in the ear may reveal vesicles.

A blood test may be done to check for Lyme disease. If a more systemic cause is suspected, a lumbar puncture may be performed. If a tumor compressing the nerve is suspected, an MRI of the head may be done.

Identification and treatment of the underlying cause (if it can be identified) may relieve symptoms for some people. The disorder may disappear on its own depending on the severity of damage to the nerve.

Corticosteroids may reduce swelling and relieve pressure on the facial nerve. Acyclovir, an antiviral agent, is used in conjunction with steroids. Lubricating eye drops or eye ointments may be recommended to protect the eye if it cannot be closed completely.

The eye may need to be patched during sleep to protect it.

Surgery to decompress the facial nerve may be recommended if a tumor is identified.

• Disfigurement from loss of facial movement
• Damage to the eye (corneal ulcers and infections)
• Chronic spasm of face muscles or eyelids
• Chronic taste abnormalities
• Aberrant regeneration (nerves grow back to the wrong structures -- for example, smiling causes the eye to close)