There are twelve pairs of cranial nerves in human beings. Facial nerve is the VII (seventh) cranial nerve among the twelve nerves. Through its long route from the brain, facial nerve innervates the muscles of the face, which allows us to laugh, cry, smile or frown. A branch of facial nerve also carries the taste fibers from the anterior one third of the tongue, through which we perceive the taste of the food that we eat.
Damage to facial nerve can impair its primary functions. Twitching, paralysis or weakness of the facial muscles is the symptom of any condition that may damage the facial nerve. There are several causes for facial nerve damage, but in most cases the etiology remains unknown.
Causes Of Damaged Facial Nerve
Head injury can affect the facial nerve, especially an injury that causes fracture of the temporal bone. It may cause excessive pressure on the nerve that may result in acute facial paralysis. However, the condition may depend on the extent of damage.
Infection of the middle ear can damage the facial nerve. Besides ear infection, infection in the brain such as meningitis and herpes virus infection can damage the nerve.
Tumor: a tumor anywhere on the path of the facial nerve can compress the facial nerve and result into facial paralysis. The common tumors include cholesteatoma, hemangioma, and tumors of salivary glands.
Facial nerve can get damaged while operating in the area from which it passes.
Symptoms Of Facial Nerve Damage
The symptoms of facial nerve damage can vary from one person to another; it depends on the extent of the nerve damage.
- The presenting symptom may be either complete paralysis of the facial muscles or partial paralysis and weakness. There may be twitching or spasms of facial muscles when the nerve is irritated. Usually the condition is unilateral, meaning one sided. The patient may be unable make facial expression and movements.
- The mouth may be drawn to the opposite side. Saliva runs down from the angle of mouth during chewing. Food may remain collected between the teeth and paralyzed cheek. There is a feeling of numbness on affected side of the cheek, but there is no loss of sensation on the skin surface.
- Together with paralysis of face there may be dryness in eyes and the patient may not be able close his eyes. He finds difficulty in raising his eyebrows. Facial nerve damage can cause loss of taste.
Treatment For Damaged Facial Nerve
The first priority before initiating the treatment is to determine the cause of facial nerve damage. For this the physician takes help of several tests such as MRI, blood examination, X-rays, and other tests if required. Besides this, the physician may clinically examine the extent of loss of facial nerve functions, such as facial muscle movement, salivary secretion, taste perception, voluntary eye closure etc.
From clinical evaluation and several tests it is possible to conclude whether the damage can result in permanent loss of function of the facial nerve, or whether the condition can revert back to normal after the treatment. Many times there is complete reversal and recovery of the facial paralysis with medicines and physio-therapy; of course it will depend on the cause.
When voluntary movements begin to return, active facial exercises should be practiced in front of the mirror several times in a day.