Smile operation or smile reconstruction is a surgical procedure that returns a smile for people with facial nerve paralysis. Facial nerve paralysis is a relatively common condition with an annual incidence of 0.25% causing loss of functioning of muscle mimics. Facial nerves secrete several branches on the face. If one or more facial nerve branches are paralyzed, the appropriate mimetic muscles lose their ability to contract. This can cause some symptoms such as eye closure incomplete with or without exposure keratitis, oral incompetence, poor articulation, dental caries, drooling, and low self-esteem. This is because different branches conserve the frontal muscles, orbicularis oculi and oris muscles, lip elevators and depressors, and platysma. The elevators of the upper lip and the corners of the mouth are innervated by the zygomatic and buccal branches. When these branches are paralyzed, there is an inability to create a symmetrical smile.
Smile operation is performed as a static or dynamic reconstruction. Examples of static reconstruction are shortening of upper or lower lip or thickening with commissure preservation. A dynamic smile reconstruction procedure restores facial nerve activity.
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The first known surgical repair of the injured facial nerve was done by Drobnick in 1879, which connected the proximal spinal accessory nerve (infecting the trapezius muscle and sternocleidomastoid) to the paralyzed facial nerve. A more symmetrical feature is the result. In 1971 new techniques for facial nerve reconstruction were introduced, as Scaramella and Smith reported on cross facial nerve grafting (CFNG) techniques for the reconstruction of a coordinated smile in cases of unilateral facial palsy. Harii et al. for the first time using free muscle transfer in combination with neural transfer in 1976. Eight years later, Terzis introduced a "baby-sitting" procedure, consisting of simultaneous parallel CFNG and hypoglossal combinations to facial nerve transfers. In 1989, Zuker et al. suggests the use of the masseter nerve as possible of the donor nerve for the innervation of the transplanted muscle in patients with Moebius syndrome.
Maps Smile surgery
Indication
The main indication for a dynamic smile reconstruction is unilateral or bilateral facial palsy due to congenital and acquired causes. Trauma, Bell's palsy and extirpation tumors are examples of secondary or acquired facial paralysis. Bell's palsy or idiopathic facial paralysis is a condition that causes facial paralysis, however, with no known cause. It has an acute onset and is largely self-limiting. But if spontaneous recurrence (close to) normal function does not occur, surgical reanimation may be indicated. Some head and neck tumors attack or suppress the facial nerves that cause paresis or facial paralysis. Examples of such tumors are facial neuromas, cholesteatomas, hemangiomas, acoustic neuromas, neoplasms or parotid gland metastases. Occasionally, the facial nerve can not be sustained during this tumor resection.
Congenital facial paralysis occurs usually unilaterally and may be complete or incomplete. The most common congenital cause is the Moebius syndrome. Moebius's syndrome is a congenital neurological disorder with bilateral paralysis of both facial and abdominal nerves. Therefore, lateral eye movement and facial animation do not exist. In Moebius-like syndrome, only one side of the face is affected, but with additional nerve palsies of the affected facial nerve and abduction.
Surgical technique
The choice of type of neural transfer is based on individual needs and patient condition. Individual factors can be patient age, paralysis type (partial or complete, uni or bilateral), denervation time of mimetic muscle, availability of nerve graft and patient's medical condition.
If facial paralysis is caused by trauma or tumor surgery, direct reinservation of the facial muscles (ideally within 72 hours of facial nerve damage) can be achieved with neurorrhaphy, with or without interposition of the nerve graft. (Algorithm 1) Neurorrhaphy is a primary end-to-end reconnection of the facial nerve stump. However, free voltage reconnection is required, otherwise scar formation may occur and the axon will regenerate beyond the facial nerve. If reconnection without stress is not possible, antposition nerve grafts are optional. Most of the auricular nerve or sural nerve is used as a transplant between two facial nerve stubs.
In longer facial paralysis, CFNG procedure or "baby-sitter" procedure is a demonstrated technique, with or without free muscle transfer. (Algorithm 1) Secondary face paralysis with a denervation time of less than 6 months may be treated with one or more facial nerve grafts (CFNGs). During a cross nerve transplant procedure one or more neural branches of the non-paralyzed face are divided and connected to one or more sural nerve grafts that tunnel to the affected side of the face. Whether the nerve graft is immediately attached to the paralytic branch of the paralyzed face or after 9 to 12 months depends on the procedure chosen.
If facial paralysis lasts between 6 months and 2 years, a "baby sitter" procedure can be used. (Algorithm 1) During this operation both CFNG and part of the undamaged donor nerve on the affected side are used. For example, the hypoglossal nerve or the masseter nerve on the affected side can be used as a donor nerve. The donor nerve is then attached to the distal end of the paralyzed facial nerve. Free muscle transplantation is sometimes shown after a "baby sitter" procedure has been performed, depending on the survival of the injured facial nerve. In other words, if there is a contraction of the mimetic muscles during the electromyogram. After about 2 years of denervation time, the atrophy of the mimetic muscles is permanent. In this case free muscle transfer is always done in combination with CFNG.
The procedure of choice for congenital facial palsy is CFNG or motor donor, both with free muscle transfer. (Algorithm 2) The incomplete bilateral Moebius syndrome has the same clinical features as the Moebius syndrome, but some motor functions still appear on one side of the face. This incomplete syndrome is revived with the use of CFNG and free muscle transfer. Cross-sectional nerve ointment comes from the side with some facial motor nerve function. But it must first be investigated if the motor function of the nerves is strong enough to be separated. Free muscle transfer is always used on the paralyzed side, because the muscles are congenital atrophic muscles. The complete bilateral Moebius syndrome is treated with motor donor nerves on both sides. The optional nerve of the donor motor is: the masseter nerve, the accessory nerve or the hypoglossal nerve. In rare cases when these nerves are also affected, the cervical nerves branch may be used. The use of free muscle transfer is again shown. The nerves that initially inhibit free muscle transfer are then connected to the branches provided by motor neural nerves. In Moebius-like syndrome, CFNG is performed, since the facial nerve on the affected side does not have strong motor function. Free muscle transfer is also used, due to atrophic muscle.
Surgical procedure
Based on the surgeon's preference, muscle gracilis, latissimus dorsi muscle, or pectoralis minor muscle are used as free neurovascular transplants. Muscular grakilis is mostly used free neurovascular muscles, as it has a reliable anatomy and is relatively easy to harvest. In addition, it can be trimmed to the correct size and volume by preserving superior contraction qualities compared to bipennate muscle, since gracilis is a parallel fibrous muscle or rope. Another advantage is the possibility for simultaneous dissection by the second team while the first team prepares the face for a free muscle transplant. Another option for free muscle transfer is the latissimus dorsi muscle. The disadvantage is that it can only be taken with the patient in the lateral or prone decubitus position. Therefore, the patient should be reversed during surgery. The advantages of the latissimus dorsi muscle are reliable anatomy and relatively simple dissection. Analog to the gracilis muscle, this muscle can be trimmed to the correct size and volume. Latisimus dorsi muscle is also a parallel fibrous muscle. The long neurovascular bundle makes one-stage face-up reactions without CFNG. By using the long thoracodorsal nerve of the latissimus dorsi muscle, direct co-ordination to the facial nerve on the other hand can be performed.
The third option is the pectoralis minor muscle, which is primarily used in children. The advantage of this muscle is its relatively small size and flat shape and fan-like, negating the need to prune without bulkin as a result. In addition, small pectoral muscles have a muscle fiber orientation similar to facial muscles. However, since muscle dissection is rather difficult and neurovascular anatomy varies, current surgeons tend to use it less frequently. Furthermore, pectoralis small muscles are not parallel fibrous muscles, and that is too much in adults.
During the one-stage or two-step CFNG procedure, one or more undesired facial nerve branches are used for reinventing the paralyzed side. In a one-step procedure, free-muscle transplantation with a dorsal graft of latissimus dorsi or a nerve graft (using a sural nerve or a saphenous nerve) can be used. The latissimus dorsi graft is used because of long thoracodorsal nerves. Therefore, it can be done directly to the normal functioning facial nerve. One stage of CFNG, implies end-to-side edral naphthalial or saphenous to end of the distal nerve of the affected face. In a two-stage procedure, incisions in front of the ear are made on the side that is not paralyzed. After electrical stimulation, the nerves that produce the best contractions of the zygomatic muscles (and the appearance of a smile) are selected. This branch is then cut. The sural or saphenous nerves as cross facial nerve graft are performed on this unaffected facial nerve branch and integrated into a paralyzed face through a subcutaneous tunnel. The end of the graft is positioned in front of the tragus (cartilage in front of the ear) on the paralyzed side. Nine to twelve months are required for axonal regeneration of facial nerve restoration, as the result of damaged neural tissue is loss of structure and axonal function. Degeneration arises distally on the paralytic faces that are paralyzed but this takes time, this process is called Wallerian degeneration. During the second stage end-to-end or end-to-end coaptation of the nerve to the proximal end of the crippled facial nerve is performed by a microscope. And transplantation of free muscle is placed, if indicated.
Similarly, a baby-sitting procedure uses CFNG, in combination with a masseter or hypoglossal nerve. In the 'nanny' procedure, the hypoglossal nerve or the masseter nerve on the affected side is identified. The donor nerve is then attached to the distal end of the paralyzed facial nerve. The technique for donor nerve transfer is the transposition of all donor nerves, partial transposition by splitting a longitudinal or indirectly hypoclossal or masseteric-facial anatomical nerve using a 'jump' interposition transplant. This is usually a large auricular or nerve sural nerve. Anastomosis of the hypoglossal or masseteric-facial nerve by using a 'jump' interposition graft can be used to directly re-arrange the paralyzed facial muscles or as a baby-sitting procedure. The purpose of the latter is only to achieve the rapid reinvention of mimetic muscles to prevent irreversible atrophy. Simultaneously one or more CFNGs are performed to ultimately reinnervate the mimetic muscle, again as a one or two stage procedure, depending on the option of free muscle graft transfer. If a two-stage procedure is performed, CFNG is connected to the distal branch of the facial nerve paralyzed during the second stage 9 to 12 months later. Donor nerves can be left intact. If free muscle transfer is indicated, this is also done in the second stage of the procedure to add the imitating muscles partially imitated by the hypoglossal nerve.
In the case of long-standing facial palsy with irreversible muscle atrophy and unavailability of the appropriate donor nerve, a free muscle graft is indicated for smile restoration, which must be reestablished by another donor nerve (usually the masseteric nerve) from end to end. ending mode. Through an incision in front of the ear, cheek spots are lifted under a layer of fat underneath. Here the nerve stimulator can be used in identifying the donor motor nerves to the masseter muscle. Once the nerve is identified, it is dissected from its connections and traced to the muscle to free as much as possible.
Results
All procedures generally show increased smile symmetry and patient satisfaction, although recovery times differ between different approaches. Primary neurorrhaphy gives the best results, because the anatomy and function of the damaged facial nerve is restored. Having primary neurorrhaphy of facial nerve means recovery time is usually 6 to 12 months. The contraction amplitude after using CFNG is usually not very strong, but it results in a relatively spontaneous smile because the contralateral healthy face core controls movement. After the CFNG procedure the first signs of reinnervation usually occur between 4 and 12 months. The use of a masseter nerve provides a number of movements that are within the normal range, resulting in a more symmetrical but not entirely emotional smile. Neural transfers use hypoglossal or masseteric nerves and the "baby sitters" procedure results in the first contraction of the imitating muscles after about 4 to 6 months. However, after the use of hypoglossal nerve control the facial movement is difficult to obtain by the patient and a spontaneous smile may not occur at all.
The true spontaneity of a smile will not occur at the same level in all dynamic reconstructions of a smile. A spontaneous smile smiles without consciously thinking about it. Primary neurorrhaphy and free muscle transfer are the only options to restore a true spontaneous smile. Although masseter nerve transfer gives a strong smile within the normal range, it never becomes completely spontaneous and emotional. But with practice, the majority of patients may give a spontaneous smile some time due to cerebral cortex plasticity. Effective rehabilitation can also prevent biting with a smile, when using a masseter nerve as a neural transfer.
Complications
There are several complications, however, most patients find them less void than the inability to smile. Common postoperative complications are infection in the site of muscle donor, facial abscess, hypertrophic scar, hematoma, and swelling of the face or place of muscle donor. In some cases of incomplete facial paralysis, the procedure decreases in function as a result. However, this improved after only a few months. Almost all procedures show synkinesis, meaning unconscious movements arise during voluntary movements. In primary neurorephrine, with or without interpositional grafts, perineural fibrosis is a common complication. With the use of CFNG there is a risk of sensory deficits at the bottom of the foot, because the sural or sapheneous nerve grafts. A visible complication with the use of the masseter nerve is the inability to chew without the appearance of a smile. The hypoglossal nerve as a donor nerve may induce tongue atrophy due to denervation.
References
Source of the article : Wikipedia
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