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Facial Nerve

What is a facial nerve

The facial nerve is the 7th of twelve cranial nerves. It emerges from the brain and goes through a complex route to reach the muscles of the face including the eyebrow and muscles closing the eye.

Causes of facial nerve palsy

The most common cause is a viral inflammation (Bells Palsy), vascular lesions and occasionally tumours (Acoustic Neuroma), parotid gland or bone tumour trauma (birth temporal bone fracture) and can lead to facial nerve palsy.

Symptoms

The paralysis usually affects one half of the face. Patients develop flattening of the affected half of the face with loss of forehead wrinkles, inability to whistle and a dragged appearance of the opposite corner of the mouth. Eye findings are out turning of the lower lid, raining of the upper lid, drooping of the brow, watering as well as dryness of the surface of the eye due to inability to close the eye.

How is it managed

If there is a definite indication of a viral origin, a short course of oral steroids and anti-viral tablets might be prescribed. In most patients however, simple lubricating eye drops and an ointment at night, use of moist chambers or taping the eyelid at night is all that needs to be done. Brain scans will be ordered if there is no recovery at six weeks or other cases are expected.

Surgical management

90% of patients with Bells Palsy due to viral inflammation have a degree of recovery by six weeks and can almost completely recover by within twelve months. Surgical procedures are therefore withheld until such time as no further recovery is expected. Other causes of the facial palsy might be permanent, but with a lesser degree of involvement.

However occasionally the degree of eye exposure is as such that immediate measures are needed to protect the surface of the eye. This is particularly relevant when the 5th nerve is also affected.

Botox

A small amount of botox in injected into the upper lid. After two to three days the eyelid will drop to cover the eye. The effect of botox is temporary and the eyelid will rise again. A rare complication such as double vision should be considered.

Tarsorraphy

Here the upper and lower lids are stitched together. The procedure can be reversed if the function of facial nerve comes back.

Permanent types of surgical procedures are withheld until no further recovery is expected. This usually happens about twelve months from the onset of Bells Palsy or earlier if the palsy is due to other causes. These are as follows:

• Correction of sagging of lower lid
• Upper lid gold/platinum weights
• Brow ptosis correction
• Treatment of watery eye in the form of botox (to treat crocodile tears), punctual plugs and tear duct operations
• Correction of dragging of the corner of the mouth by muscle or nerve transfer.