Patients with advanced facial palsy often develop sequelae of facial muscle linkage, causing various discomforts or ailments in daily life. The most painful thing for patients is the inconsistency between their inner emotions and their expressions after linkage, and the inability to laugh when they want to. Patients often complain that sometimes it is worse to laugh than to cry. This asymmetrical facial expression often causes misunderstanding in social interaction. Patients with facial muscle linkage are in great pain. However, there was no effective means to repair it before. For this reason, I designed this procedure based on my many years of clinical experience in repairing facial palsy in the hope of repairing facial muscle linkage or helping to improve the pain of patients with facial muscle linkage. I searched the web to find relevant literature and was disappointed. I found that viewing my original paper not only required a fee, but most of them were pinched, misquoted, and not attributed. The most intolerable thing is that the references in the article are incorrectly labeled and reposted as the original text, resulting in numerous errors and misrepresentations. I hope that readers can understand the process and overview of my design of facial muscle linkage repair surgery, which still needs to be improved, and I hope that my colleagues can give me advice and criticism.
Objective: Some patients with facial palsy, after recovery of the facial nerve, have symptoms of associated movements of the affected lateral muscles, mismovement and relatively strong muscles of the healthy lateral muscles, resulting in grotesque facial expressions and inability to express emotions accurately. In this design, the facial muscles were regulated by transplanting the affected side of the healthy lateral nerve and transposing the branches of the affected lateral nerve, so that the facial muscles with associated movements on the affected side could be separated and the facial muscles with mismovement could be synchronized with the expression movements on the healthy side, thus restoring the patient’s natural symmetrical smile.
Method: The branch of the lateral nerve on the healthy side is cut off highly selectively, and the nerve power from the healthy side is transferred to the affected side through a nerve graft, after the regeneration of the graft reaches the affected side, the branch of the innervated nerve of the linked facial muscle on the affected side is separated and cut off, and the distal end of the branch is transposed and anastomosed with the graft transferred from the healthy side, so that the power provided by the lateral nerve on the healthy side can innervate part of the linked facial muscle on the affected side and make it obtain a synchronized movement with the healthy side. The movement was synchronized with that of the healthy side.
RESULTS: A total of 11 patients have undergone facial nerve modulation for repair since 2003. In the postoperative follow-up cases, the mouth-eye linkage disappeared and the synchronized smiling movement was restored in both corners of the mouth.
CONCLUSION: Facial nerve modulation can repair the facial muscle linkage after facial palsy.
Facial muscle linkage disorder is often manifested by the linked activity of the affected side of the eye and the corners of the mouth, which has a greater impact on the patient’s facial expression activity [1]. When the patient smiles, the affected corner of the mouth cannot be lifted, but when the eyes are closed, the affected corner of the mouth is lifted, and the cheeks are twisted. Such grotesque expressions often cause social difficulties for patients, which is the most common reason for patients to seek medical attention, yet fail to obtain effective methods of treatment. For this reason, I designed a facial nerve graft and transposition for repair, and obtained better results by clinical application.
1. Surgical method
1.1 Selection of the branch of the lateral nerve on the healthy side: Phase I surgery: transfer of the power of the healthy lateral nerve. An incision is made in front of the ear on the healthy side, and the zygomatic and superior buccal branches of the facial nerve are separated superficially along the parotid fascia, and the zygomatic and superior buccal branches of the facial nerve (depending on the variation of the facial nerve branches) are revealed in front of the parotid fascia. Under the positioning of the nerve electrical stimulator, some of the fourth-grade branches of the healthy facial nerve corresponding to the tertiary branches of the affected misfiring muscles are first cut off highly selectively for use, mostly the innervated nerves of the zygomaticus major, superior labial raphe and laughing muscles.
1.2 Autologous transfacial nerve transplantation: about 15-20 cm of autologous peroneal nerve was cut as the graft, and the distal end of the transplanted nerve was anastomosed with the proximal end of the severed branch of the healthy lateral nerve and transplanted to the affected side through the subcutaneous tunnel of the cheek via the upper lip, and the distal end of the transplanted nerve was marked with a black suture and placed under the skin in front of the ear screen on the affected side. After 10-12 months, if it is confirmed that the transplanted nerve has regenerated and the length of the regenerated nerve has reached the distal end, the power of the lateral nerve on the healthy side can be transmitted to the affected side via the transplanted nerve, then the second stage of surgery is feasible.
1.3 Isolation of the associated nerve on the affected side: Phase II surgery: to restore the expression activity of the affected angle of the mouth in synchronization with that of the healthy side. Through the preauricular incision on the affected side, the grafted nerve is revealed through black suture markers, and the branches of the affected lateral nerve are revealed in the same way as on the healthy side. Under the positioning of the electrical nerve stimulator, the fourth level branches of the affected side of the associated facial nerve (mostly the branches of the zygomatic branch or the upper buccal branch) were cut off in a highly selective manner, so that the associated facial muscle was dissociated from the branch of the innervated nerve that made the association.
1.4 Transposition of the affected facial nerve branch and anastomosis with the graft: The distal end of the disconnected innervated nerve branch on the affected side was transposed and anastomosed with the proximal end of the graft transferred from the healthy side. After 4-6 months of nerve regeneration, the power provided by the healthy lateral nerve can innervate part of the facial muscle of the affected side that was originally linked to the motor band, so that the facial muscle can obtain synchronized movements with the healthy side. By transplantation and transposition of the facial nerve, it is possible to regulate the muscle strength of the facial muscles on the healthy side and to separate the movements of the facial muscles on the affected side, while the contraction of the zygomaticus major and the smiling muscles on the affected side can be synchronized with that of the healthy side, thus restoring symmetrical facial movements and smiling expressions at the corners of the mouth.
2. Clinical data
2.1 General data: From 2003 to the present, there were 11 surgically repaired patients in this group, 5 males and 6 females. The maximum age was 55 years old, the minimum age was 13 years old, and the average age was 28 years old. The average disease duration was 15 years, the longest 21 years and the shortest 8 months. Etiology: 4 cases of postoperative facial tumor, 5 cases of facial trauma, and 2 cases of unknown cause. All cases in this group were left with oculo-ocular linkage and were repaired by applying facial nerve modulation.
2.2 Results: The cases in this group underwent smooth surgery and the incisions healed well. In the 6 cases that were followed up to postoperatively, the affected side of the orofacial angle activity was completely separated from the eyelid movement. The symmetry of the corners of the mouth during smiling was significantly improved compared to the preoperative period and is still under continuous follow-up.
2.3 Typical case Female, 30 years old. In January 2006, she underwent a one-stage surgery with selective excision of the left facial nerve and collapsed facial nerve graft under general anesthesia. The peroneal nerve was cut for about 20 cm and sutured to the zygomatic branch of the left facial nerve, which was placed in front of the left ear through a subcutaneous tunnel through the upper lip to the right face. In December 2006, the second-stage surgery was performed, and the postoperative ocular and orofacial movements were separated. in March 2007, the orofacial movements on the affected side began to recover, and in the follow-up in July 2007, the face was symmetrical when the eyes were closed, and the expression was natural when smiling.
3. Discussion
3.1 Clinical manifestations and pathogenesis of facial muscle linkage: The common clinical manifestations are: both sides of the face are still symmetrical when the patient is at rest, but each eyelid closing movement on the affected side is accompanied by a twitch of the affected side’s corner of the mouth or cheek. When smiling, the affected side of the mouth does not lift up normally but tilts toward the healthy side, but when the affected side closes its eyes, the corner of the mouth tilts toward the affected side, and the harder the active eye closure is, the more the affected side of the mouth tilts. In some cases, each time the eyes are blinked, it is accompanied by involuntary twitching of the affected side of the mouth.
After the axial bundle of the facial nerve is broken by trauma or degeneration by inflammation, some of the regenerated axial bundles of the original branch of the nerve innervating the orbicularis oculi muscle (zygomatic branch), in addition to restoring the innervation of the orbicularis oculi muscle, some other axial bundles make mistakes in the process of regeneration and enter the innervation nerve of the zygomaticus muscle and the laughing muscle by mistake, and become connected with the zygomaticus muscle and the laughing muscle on the affected side. The connection with the affected zygomatic and laughing muscles. Therefore, whenever the patient closes the eyes, the orbicularis oculi muscle contracts at the same time as the zygomaticus, superior labial raphe and the laughing muscle, thus triggering the oculofacial muscle linkage. Due to the complexity of the pathogenesis, it is very difficult to locate the site where the misconnection occurs during nerve regeneration. Therefore, repair of the oculo-oral linkage is quite complex, difficult and challenging.
3.2 Differentiation of facial muscle linkage from facial spasm: Facial spasm, also known as facial tics, is common in clinical practice. It is a paroxysmal, tonic, irregular, involuntary spasm or convulsion of the facial muscles innervated by the facial nerve, with the eyes and corners of the mouth being the most common. It usually occurs on one side of the face and is occasionally seen on both sides. Mild facial paralysis may occur in a small number of patients. The pathogenesis of facial muscle spasm has not been elucidated and the etiology is complex and needs to be further explored. Recent studies have suggested that facial myospasm is triggered by compression of the facial nerve by intracranial or skull base vascular causes or non-vascular occupying lesions [4]. Therefore, the treatment of facial muscle spasm is beyond the scope of this article and will not be explored here. The clinical presentation of facial muscle linkage is characterized by the patient’s inability to smile naturally but to manipulate the corners of the mouth through voluntary eye closure movements. This is very different from facial spasm.
3.3 Current status of treatment of facial muscle linkage: There is no effective treatment method in the past. Non-surgical treatments are feasible with linked facial muscle type A botulinum toxin injections, but the remission period is short and not curative [3]. The surgical method is mainly selective excision of facial nerve branches, which results in partial damage of facial nerve branches and paralysis of some facial muscles to alleviate linkage without restoring normal expression of the affected face. Although transfacial nerve grafting has been used for many years to repair facial palsy, no repair of facial muscle linkage has been reported [2].
3. 4 The design idea of repairing facial muscle linkage: according to the pathogenesis of posterior muscle linkage in facial palsy, the following four repair steps are designed: 1 Cut the corresponding nerve branch on the healthy side – reduce the muscle strength on the healthy side. 2 Nerve branch on the healthy side via transfacial nerve graft – nerve 3. cut the linked nerve – termination of the linkage. 4. transposition of the linked nerve and anastomosis with the healthy graft – synchronized activity of the affected facial muscle with the healthy side.
Since the facial nerve on the affected side had a process of injury and then regeneration, the muscle force on the affected side is weaker than that on the healthy side. Part of the branch of the healthy lateral nerve that innervates the orofacial movement is cut off to reduce the muscle force on the healthy side to facilitate the balance of muscle force on both sides. This nerve branch is used as the driving force and transferred to the affected side by nerve grafting. After separating the linked nerve between the affected side of the eye and the angle of the mouth, the grafted nerve is sutured to the nerve branch that moves the angle of the mouth, so that the affected side of the angle of the mouth can restore the movement synchronized with that of the healthy side. As the linkage between the eye and the corner of the mouth is separated, the affected side of the corner of the mouth can obtain an expression movement synchronized with that of the healthy side. Since it is difficult to precisely locate the site of nerve misconnection, this procedure avoids the main trunk and secondary branches of the facial nerve, and instead cuts and separates the fourth level branches before the nerve enters the muscle. In this way, not only the connected nerve is completely separated but also other nerve branches are reduced to be accidentally injured.
3.5 Indications for surgery: After facial palsy, patients who have facial expression muscles with linkage and misalignment, obvious eye-oral angle linkage, sufficient muscle strength for zygomatic muscles and laughing muscles, ability to lift the affected angle of the mouth with eyes closed, and a strong desire for repair are the indications for surgery. Therefore, the selection of the surgical case has a decisive influence on the final result of the surgery. If the affected facial muscles have extensive linkage and weak muscle strength, the surgery can only improve the smile by separating the linkage, and the improvement of facial symmetry is still unsatisfactory. Only if the facial palsy is partially recovered and more facial muscles are preserved, patients with strong muscles on the affected side may have better results if the oculo-oral linkage is separated after surgery, but still maintain strong muscles. The final surgical outcome depends on the patient’s own condition and the status of nerve regeneration, which must be discussed with the patient prior to surgery. In contrast, paroxysmal, involuntary facial muscle cascade movements in patients with facial spasm are not effective.
3.6 The recovery period of the surgery is long: because the transfacial nerve graft is long (about 15-20 CM) and has to pass through two anastomoses, even if the best regeneration rate is achieved, less than 50% of the regenerated nerve bundles reach the affected facial muscles, and both the patient and the doctor must have a solid knowledge of the surgical results. Nerve regeneration may take up to 12 months to recover after primary surgery, and after 4-6 months, the site of nerve regeneration can be estimated by the Tinel sign test. This is done by gently tapping along the course of the subcutaneous tunnel of the graft from distal to proximal until a numbing pinprick sensation occurs in the distal end, which is the site of axonal regeneration, usually within 2-3 cm. If it has grown to the desired site, it is generally considered that there is still a further delay of 3 months before the second stage surgery can be performed. The patient has to wait about one year from the end of the phase I surgery to the phase II surgery, and there is a recovery period of 4-6 months after the phase II surgery, during which the linked facial muscles are paralyzed due to the dissociation of the original innervated nerve, and the paralyzed facial muscles have to wait for the regeneration of the transplanted nerve to grow in before they can have functional contraction. Therefore, the entire repair period may take up to 24 months, and the patient must understand the slow and difficult nature of nerve regeneration.
3.7 Accurate positioning of facial nerve branches: Because of the delicate and colorful facial expression and the extremely complex axial bundle of the nerve, careful and precise positioning and manipulation of the innervation of the nerve is necessary to obtain the desired result, and a mis-cutting of the facial nerve branches may result in irreparable consequences.
3.8 The importance of facial muscle re-education: After successful surgery, since the innervation of the linked facial muscles has changed, to restore a coordinated and natural smile, the patient is required to face a mirror and conduct active re-education training on the restored innervation of the facial muscles under direct vision. Make the successful surgical outcome better.