The facial nerve is the 7th of the twelve cranial nerves. Though it has some sensory supply to some structures it mainly supplies the muscles of the face responsible for facial expression. Injury to this nerve will result in paralysis of that side of the face resulting in facial asymmetry and inability to close the eye. As a result of the weakness or paralysis of the facial muscles the face sags and mouth becomes “crooked” when the patient smiles. As the patient is unable to close the eye or even blink, continuous exposure of the eye to air results in dryness of the eye and damage to the conjunctiva and cornea. The resulting deformity may have significant health and social implications.
The facial nerve arises from the brain stem and passes through a foramen located next to the inner ear and it enters the middle ear. It exits the ear just below the ear and deep to the angle of the jaw. It then enters the parotid gland. The main trunk of the nerve then divides into an upper and lower branch and subsequently divides into five branches which supply the muscles of the face.
To avoid injury to the nerve during the surgery it must be identified and all branches protected. Very meticulous dissection and good surgical skills are required.
What is SUPERFICIAL PAROTIDECTOMY?
Most parotid tumours are superficial to the facial nerve and therefore require removal of the parotid gland that is superficial to it. The surgery is called SUPERFICIAL PAROTIDECTOMY. No manipulation or mobilisation of the nerve is necessary in these cases.
What is TOTAL PAROTIDECTOMY?
Some tumours may arise from the parotid tissue that is deep the nerve.In such cases some branches of the nerve may have to be retracted and mobilised to be able to remove the tumour deep to the nerve. As both the superficial and deep lobe are removed the surgery is called TOTAL PAROTIDECTOMY. Some weakness of the facial muscles may result from the manipulation of the nerve. It is often temporary.