Facial nerve has a lot of functions in the face, the most important of which is controlling the facial muscles. Injury of the facial nerve causes paralysis of these muscles. The facial muscles can be divided to several groups according to the function of each muscle. Some of them are controlling eye movements, others are controlling the lips movements (The most important of which is smiling) and other muscles have a role in forehead movements.
There are too many causes for facial nerve paralysis. These causes cannot be gathered in a single article. Causes of facial nerve paralysis include but are not limited to brain tumors, resection of facial nerve during treating a brain tumors, fracture base of the skull, facial injuries and cut wounds of the face that leads to direct injury of the facial nerve and also facial nerve injury can occur due to facial surgeries specially surgery of the parotid gland.
Of course not all cases of facial nerve injuries are due to direct trauma of the facial nerve, some diseases or inflammation can cause facial nerve paralysis.
Bell`s palsy: a lot of people calls any case of facial paralysis as Bell`s palsy, which is a common mistake. Actually Bell`s palsy is a special type of facial paralysis and occurs without a trauma or an accident to the facial nerve. Bell`s palsy affects any age or sex. There is an increased incidence of facial paralysis in pregnant ladies and diabetics.
Facial nerve has a lot of functions in the face, the most important of which is controlling the facial muscles. Injury of the facial nerve causes paralysis of these muscles. The facial muscles can be divided to several groups according to the function of each muscle. Some of them are controlling eye movements, others are controlling the lips movements (The most important of which is smiling) and other muscles have a role in forehead movements.
Generally speaking, the facial movements depend on the existence of an intact facial nerve and well functioning facial muscles. In case any of them are injured, the facial movements will be affected either partially or completely according to the degree and site of injury.
Manifestations of facial paralysis:
The eye:
Facial paralysis leads to inability to close the eyelids. This leaves the eye unprotected and exposed for a long duration which leads to eye dryness and recurrent attacks of inflammations. Several attacks of inflammations and infections will eventually affects the vision which may be lost completely.
The upper and lower lips:
Facial paralysis leads to loss of movements of the upper, lower lips and the mouth. Deviation of the mouth to the unaffected side is evident and inability to smile is severely distressing.
Treatment of facial paralysis:
Information mentioned here is just a hint about the methods of treatment of facial paralysis. Several methods of treatment of facial paralysis are available and the exact method suitable for treatment of each individual case can not be determined except after direct consultation of the facial nerve surgery expert.
To achieve the best results, the best methods of treatment should be chosen. The method of treatment varies from one case to another according to the circumstances of each case. The exact method of treatment is tailored according to each patient circumstance. The method of treatment is chosen according to several factors. These factors include but not limited to the cause of facial paralysis, degree of paralysis, duration of paralysis, age of the patient and the general health condition.
Medical treatment:
Medical treatment is only described in early cases in which the cause is not due to trauma, tumor excision or any other causes of direct cut of the nerve. The medical treatment varies according to the cause of the paralysis but generally contains eye drops and lubricants to protect the eye.
Surgical treatment:
A lot of surgeries are described to treat facial paralysis. Only an expert in this field can choose what is suitable for each patient. One of the most important factors in determining the plan for facial reanimation is the time that had elapsed from the onset of paralysis. The duration of facial paralysis affects to a great extent the nature of the used method of treatment. To explain this point we have to know that denervating a muscle (cutting the nerve that supplies this muscle) will prevent this muscle from contraction. As more and more time elapses, the muscle will not respond and contract even if the nerve is reconnected again. In such a case the doctor should search for another method of treatment rather than reconnecting the nerve. Most of the scientific research agreed that the duration in which you can reconnect the facial nerve to supply the same existing facial muscles is one year. After this duration another method of treatment should be chosen. According to that, cases of facial paralysis that need surgical treatment can be classified into early cases and late cases
Early cases (within one year from the onset of paralysis):
In these cases the expert surgeon will try to reconnect the neural supply to the facial muscles. After taking this decision, the first question that comes to mind is the source of this neural supply. The best source is the same existing stump of the injured facial nerve. However this is not always possible as in cases of facial paralysis due to fracture base of skull of removal of intracranial tumors. In such cases, the expert surgeon will search for another source of neural supply. One of the most famous sources of neural supply in the past century is the contralateral facial nerve. Nowadays it is proven that this source is not enough to move the whole face. One of the most common sources to move the face is the 12th and 5th cranial nerves.
Late cases (after more than one year from the onset of facial paralysis)
In such cases, it is not preferable to use the same existing facial muscles as scientific researches proved that after this period it is unlikely that the facial muscles will respond adequately to the coming nerve impulses. So other procedures should be done and the face is treated segmentally:
The eye
The facial nerve is the nerve responsible for eye closure. So after facial nerve paralysis, the eye may be severely affected due to dryness and repeated attacks of infection and may finally lead to corneal perforation and even blindness. In addition to eye affection the lower eye lid is sagging and the eye will look aesthetically unpleasant and different from the other eye.
Treatment of the upper eyelid
There are several ways to treat the upper eyelid, the commonest of which is implantation of gold plate in the upper eyelid. The weight of the gold will help the upper eyelid to close more efficiently. The gold is specially used because it is inert, with high density (you can put and adequate weight in a small gold plate) and also has a perfect color match so it will not show when implanted under the skin. There are other methods to treat the eyelids like transfer of the temporalis muscle( a muscle at the side of the head) but the gold plate is considered a more effective and simple method
Treatment of the lower eyelid
Several methods are available to treat the lower eye lid including lid shortening, suspension and tarsorraphy.
B) The smile
The smile stays as one of the most distressing factor to patients of facial paralysis. Fortunately progressive improvements occurred in this field and led to achievement of the best possible smile.
Historically, several trials are attempted to rebalance the face in patients with facial paralysis. The first of these trials were through implantation of threads of slings between the side of the head and the corner of mouth to prevent the over traction of the mouth to the healthy side of the face. Of course the results were unsatisfactory. After that, trial to implant muscles at the side of the mouth to make it capable of smiling. The first of these trials were through transfer of muscles of mastication to the crer of the mouth. Although this is a simple technique, it did not give the best available results for a lot of reasons as the patient has to clinch his teeth in order to smile and also involuntary smiling movement occurred during eating. As a conclusion, the smile was not natural.
State of the art in smile restoration:
The transfer of a muscle from another part of the body to the face is the most recent advance and best option in smile restoration in delayed cases of facial paralysis. The expert surgeon transfers a small piece of muscle from another part of the body to the face. This small piece is accompanied with its blood supply and nerve supply. The transferred muscle is implanted n an appropriate position in the face. The blood vessels are connected to blood vessels in the face to ensure survival of the transplanted muscles. The nerve of the muscle is sutured to another nerve in the face. The surgeon should be highly experienced in the fields of facial nerve and microsurgery. After 6 months, the muscle starts to move and through some exercises the movement starts to be more natural. D. Tarek Amer has a lot of scientific articles published in European and American medical journals in the field of smile restoration through microsurgery.