Facial palsy

• What is facial palsy?

Facial palsy is paralysis of part of the face caused by a non-functioning facial nerve that controls the muscles, especially around the eye and mouth. The facial nerve is also called the seventh cranial nerve and controls the muscles that lift the eyebrows, the muscles that close the eyelids, the muscles of the cheek and around the mouth.

• What are the causes of facial palsy?

Facial palsy can be congenital or acquired, possibly following a viral illness or through no obvious cause. Under these circumstances, it is referred to as Bell's palsy. Sometimes a tumor can compress and damage the nerve. Other causes include serious infections and skull fracture.

• What are the symptoms of facial palsy?

Facial paralysis usually affects half the face. There is loss of forehead lines and wrinkles, droopy eyebrow, difficulty closing the eye, inability to smile or whistle and the corner of the mouth is pulled down.

The effects on the eyes are particularly significant. The upper eyelid can be a little too high and the lower eyelid can sag and turn outward (ectropion), resulting in a watering eye, inability to close the eye and exposure or drying of the cornea. The eye can become red, vision can blur and sight is occasionally affected by ulceration and scarring (exposure keratopathy).

More unusual problems include loss of the nerve (the trigeminal, or fifth cranial nerve) that controls sensation in the eye. This usually happens as a result of surgery on a large, benign brain tumor (an acoustic neuroma), which has affected both the facial nerve to the muscles and the sensory nerve to the front of the eye.

These patients may suffer a lack of sensation on the surface of the eye (cornea), so that they cannot feel dryness, foreign bodies or injuries to the surface of the eye. This puts them at risk of developing a corneal ulcer and suffering severe or permanent damage to their sight.

Crocodile tears are another rare consequence of facial nerve paralysis. They occur when the damaged nerve tries to grow back along its old pathway but goes instead to the tear (lacrimal) gland and to the muscles of the jaw. This results in tears when the patient chews.

Other consequences of a nerve regrowing in the wrong direction include involuntary closing of the eyelid and muscle spasms in the eyelid, cheek and around the mouth (aberrant regeneration of the seventh nerve).

• How can this condition be treated?

- Medical Management

Topical lubricant eye drops and ointment are the mainstay of management. Taping the eyelids shut at bedtime can be beneficial, but, if not done properly can allow the eyelid to remain open and unintentionally damage the cornea. Some patients need to have their upper eyelid lowered with Botox to paralyze the muscle which opens the eye. This allows the eyelid to drop over the surface of the eye and protect it.

Crocodile tears and aberrant regeneration of seventh nerve can all be effectively managed with regular Botox injections.

- Surgery

When there is a risk of corneal exposure from incomplete eyelid closure, surgery is a treatment option. It can also improve facial symmetry and eyelid function and reduce eye watering.

• There are many different procedures