Anatomical research and clinical applications of masseter nerve in intermediate duration facial paralysis treatment

The early recovery time of the nerve VII after MN transfer helps to

reduce facial area muscle degeneration, to increase the results of movement

recovery. As the medical literature has shown, before being used as a major

nerve for transmission recoveryof the nerve VII, MN has been used as a

support nerve (babysitter) while waiting for facial nerves that continued to

transmit.

The average time of the first commissure excursion movement in our

studies in coaptedbuccal branch group is 5.6 months, 5.75 months for the two

branch coapted group and 5.4 months for the main bodycoapted group.

According to Wang's report, this time is 6 months, Klebuc is 5.6 months. We

found that from the time we saw the time onset of vibrationuntil the patient

clearly and well movecommissure excursion with the bitting, it is quite fast

with 1 month on the average. This suggests that if there is a neurotransmitter,

the nervous movement recoveryappears and the movements will be

performed.

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ysis treatment (<2 years) Intermediate durationfacial paralysishas the ability to restore the nerve VII transmission to recover the movement of the muscles clinging to face skin, it is very positive because at this time the muscles clinging to face skin is not degenerated, not atrophied. With studies using nervous sources to recover the nerve VII transmission from MN, many reports show very positive results even up to 24 4 month paralysis. The authors suppose that due to distance of MN to the nerve VII branches is quite close and the number of axons of MN is two to three times higher than the number of axons of the wire VII branches, so the ability to recover is higher than other nerves. The synergy issue is also mentioned by the authors, but the reports show that this is not too big issue for patients nor affect surgical results. 1.3.2. Using MN source in chronicfacial paralysis (> 2 years) Like the direct transfer of MN, the use of MN for muscle transplantation has many advantages such as ease of surgery, short recovery time, the used nerve does not affect the function. However, the authors also said that the use has disadvantages such as when lifting the edge, it is necessary to bite with the bitting and the time to create a natural smile must be 2-4 years after surgery. To overcome this problem, some authors have used dual nervous joint with two places: MN and facial nerves with the movement nerves of the grafted muscle to create spontaneous and natural laughs. In 2012, Biglioli reported a series of free muscle grafts, with two nervous sources (MN, facial nerves) and very positive results. In the future, functional magnetic resonance imaging may be used to study this process in facial paralysis and to explore the cortex areas that are activated while smiling with the patients who use MN as source of free muscle transplantation. To achieve in spontaneous way, symmetrical smiles, an important part is due to post-operative recovery of smile function when standing in front of the mirror with exercises and biofeedback. 1.3.3. In Viet Nam 5 In Vietnam, peripheral neuropathy joint techniques are also performed by many surgeons in orthopedic, neurosurgical and jaw surgery. From the 1990s, N.B. Hung (1998), N.H.Phan (1999) used micro vascular-neuro- microsurgical techniques to more accurately suture and join, Dr. Son (2000) reported on the technique of suturing and covering the bundle of fibers in the nervous joint and transplant. The use of facial nerves in the nerve VII recovery has also been reported by author N.T.Son since 2003, with positive results and one of the options in the facial paralysis treatment. Studies on anatomy and MN applications have also been reported, but there have been no further studies on anatomy and application on Vietnamese people. 6 Chapter 2 RESEARCH SUBJECTS AND METHODS 2.1. Research subjects - Research on fresh cadaver: 22 specimens /11 fresh cadaver (including 6 men and 5 women) from 35-73 years old, 9 fresh cadaver were studied in Ho Chi Minh City University of Medicine and Pharmacy, 02 fresh cadaver at Viet Duc Hospital, unknown age (unidentified cadaver) - Clinical research: Patients with facial paralysisdue to various causes in the period from 3 weeks to 24 months had surgery to transfer one-sidedness MN at the Department of Maxillofacial Surgery-Plastic Surgery-Aesthetics, Viet Duc Hospital from 11 / 2009-12 / 2017. 2.1.1. Selection criteria and exclusion of patients - Criteria for selection on cadaver: The specimens on the fresh cadaver are intact in the face area, have not been surgically or previously injured. Exclude specimens that are not properly preserved, face areas are injured. - Criteria for patients selection: Patients with facial paralysisaccording to FNGS 2.0 classification from grade 4 to grade 6 for not more than 24 months paralysis; The patients were diagnosed with intermediate durationfacial paralysis; For facial paralysis patients with unidentified paralysis causes (Bell paralysis), the time for surgery indication is more than 6 months if there is no sign of clinical recovery; There are no systemic diseases that endanger the surgery; had surgical treatment in plastic surgery and maxillofacial surgery; Follow up patients after periodic treatment of 1 month, 3 months ... until the end of the studies. 2.2. RESEARCH METHODS 7 2.2.1. Research design: - Research on fresh cadaver: Observation and description research - Clinical research: Retrospective, prospective, clinical intervention, non- controlled 2.2.2. Research facilities and equipment - Research on fresh cadaver: + Use surgical instruments, measurer, loupe + Carry out the surgery on each side of fresh corpse, with supine position of the head tilted to the opposite side. + Skin incision along Blair incision line from the temple through the tragus to the jaw corner about 1/3 of the length of mandibularbone. + Operate of the facial muscle layer, operate to the front bank, the bank on the salivary glands. + From the anterior border of the parotid glands, operate to find branches of the nerve VII: the mouth branch, the cheek branch. Then retrograde surgery into the parotid salivary glands. + Remove the shallow lobe of glands that preserve nerve VII branches. + Reveal the whole nerve VII. + Continue to remove the deep lobe to expose the entire masseter muscle below. + Measure the index of masseter muscle as below. + Continue operating the layers of masseter muscle, peeling according to the layers. + Find donor nerve and masseter muscle arteries in the deep layer of masseter muscle. + Measure indicators. 8 - Clinical research: + Clinical examination of the patients: assessing injury status of the nerve VII according to House and Brackmann score (FNGS 2.0); measure commissure excursion amplitude; assessment of facial nerve injury; masseteric muscle function; classify causes of injury; body situation. + Subclinical assessment: MRI, CT to search for causes of the nerve VII injury; EMG to determine vulnerability; do tests to exclude other diseases. + Perform the surgery 2.2.3. Improved content in surgery to find MN Through clinical and anatomical researches on the fresh cadaver, we map out the "MN zone” as follows: + Upper limit: zygomatic branch. + Lower limit: buccal branch + Posterior limit: the parallel line and measure the distance from the tragus to the branching position of MN. + Anterior limit: the line parallel to the posterior limit and about 1cm from the posterior limit. MN zone is limited when connected 04 lines above and in the deep layer of masseter muscle. 2.2.4. Follow uppost operation - The patient was monitored at the hospital during 5-07 days. - Follow up immediately after surgery about hematoma, bleeding, infection. - Periodic observation: 03 months, 06 months, 12 months to assess the time of axon regeneration by manifesting the movement of facial muscles clinically. - Evaluation of the time onset of vibration based on the patient perception when biting, it will result in muscle vibrations of the mouth in paralysis side. 9 - Evaluate the time when the patients can laugh spontaneously without bitting. - Evaluate postoperative masseter muscle function: measuring the maximum distance of the mouth opening, the patient's ability to chew. - Evaluate by observation, grading according to FNGS 2.0, measure commissure excursion calculated from the middle of the upper lip. Compare before and after surgery by taking pictures, filming, electromyography. 2.2.5. Rehabilitation post operation - Immediately during the first week after surgery, the patient is instructed to eat by chewing on the surgery side to increase neurotransmitter ability. - The first month after surgery, the patient does not massage the surgical side. Gentle massage will be performed after surgery from the second month. - The patient will practice regular chewing on the surgical side until the first signs of muscle self-perceived by the patient for 3-6 months. - After the first signs of muscle vibration, the patient will have to practice in front of the mirror: clenching the teeth with a smirk, and making symestry smile at least 02-03 times / day. Every 15-20 minutes. - Rehabilitation with the mirror will help patients to separate movements by adjusting the bitting force. Therefore, it limits the synkinesis. - Patients will always understand that biting will motivate and equilibrate mouth corners, which will help create a pathway from the adaptor cortical and patients can have a natural, spontaneous smile after the practice from 24-72 months. 10 2.3. Data processing - Analysis on software STATA 12.0 - Research classification is as follows: Type 1: Very good - FNGS 2.0: Grade I, Grade II. - Electromechanics: There are signs of the movement unit of the facial muscle (optional conditions). - Spontaneaous smile - Difference in amplitude from the healthy side is <3 mm. Type 2: Good - FNGS 2.0: Grade I, Grade II. - Electromechanics: There are signs of the movement unit of the facial muscle(optional conditions). - Movement needs bit with bitting - Difference in amplitude from the healthy side is <5 mm. Type 3: Fairly - FNGS 2.0: Grade III - Electromechanics: There are signs of the movement unit of the facial muscle(optional conditions). - Movement needs bit with bitting - Difference in amplitude from the healthy side is ≥5 mm. Type 4: Average - FNGS 2.0: Grade IV - Movement needs bit with bitting - Difference in amplitude from the healthy side is >5 mm. - Electromechanics: There are signs of the movement unit of the facial 11 muscle(optional conditions). Type 5: Poor - FNGS 2.0: Grade V, VI - Movement needs bit with bitting - Difference in amplitude of the mouth movement calculeted from the upper lip middle is small or quite zero. - Electromechanics: There is no electric potential difference when biting 2.4. Ethics in research - Objectives and methods should be considered carefully so that the benefit of patients is priority 1. - Patients voluntarily participate in research - Information security and use for research purposes. 12 Chapter 3 RESEARCH RESULTS 3.1. Research results of MN anatomy Observe 22 cadaver specimens (12 men, 10 women), average age of 69.7; number of bite layers: 3; masseter muscle length: 64.4 ± 3.9; masseter muscle width: 37.4 ± 3.6. The distance from the tragus to the branching point under MN is 33.2 ± 2.6; The distance from the cheek bow to the branching point under MN is 7.8 ± 0.8; The distance from the zygomatic arch to the branching point under MN is 5.8 ± 0.8; The distance from the jaw corner to MN is 54.2 ± 12.6; The distance from the mouth branch of the nerve VII to the branching point under MN is 11.2 ± 3.0. There are no statistically significant differences in men and women. There is difference, but not statistically significant between the MN location on the corpse and on the surgery, the distance from the tragus to MN on the corpse is larger than on the surgery but not significant. MN was found in the deep layer of the masseter muscle and between the cheekbone branch and the mouth branch of the nerve VII, before the tragus 29.9 ± 2.5 mm. 3.2. Surgical results 3.2.1. Short term results Complications after surgery: Infection, fluid accumulation, saliva leakage are not seen in any case. The effect of the proximal results is calculated on the time of time onset of vibrationand the commissure excursion movement when biting after surgery. Table 3.13.Onset-vibration muscle time with the bitting (n = 32) 13 Time of the first muscle vibration (month) Mean ± SD Min – Max P Coaptation to the buccal branch (n=23) 3.5 ± 1.1 2 – 6 0.045 Coaptation to the buccal and zygoma branch (n=4) 4.3 ± 1.5 3 – 6 Coaptation to the main trunk (n=5) 4.6 ± 0.5 4 – 5 All the cases (n=32) 4.3 ± 3.7 2 – 6 Remark: After surgery, the time of the time onset of vibrationwith the bitting is 3.5 ± 1, 07 months; of the group coapted 02 branches is 4.3 ± 1.5 months; with the main body joint group is 4.6 ± 0.5 months and the average is 4.3 ± 3.7 months. This difference is statistically significant with p <0.05. The sign of the time onset of vibrationwas felt by the patient itself, so only 32 patients reported the time of the first muscle vibration when the jaw was closed. Table 3.14 Onset motion time with the bittingand grading according to FNGS 2.0 Coaptation to the buccal branch (n=23) Mean ± SD 5.6 ± 3.8 Min – Max 3 – 24 Coaptation to the buccal and zygoma branch (n=4) Mean ± SD 5.75 ± 0.5 Min – Max 5-6 Coaptation to the main trunk (n=5) Mean ± SD 5.4 ± 0.9 Min – Max 4 – 6 All the cases (n=32) Mean ± SD 5.6 ± 3.4 Min - Max 3 – 24 The first commissure excursion on the paralysis side with bitting (n=30) Mean ± SD 5.4 ± 2.1 Min – Max 3 – 9 Grade I 0 0 Grade II 4 13.3 Grade III 21 70,0 14 FNGS 2.0 (n=30) Grade IV 5 16.7 Grade V 0 0 Grade VI 0 0 Remark: The time averageof the first commissure excursion movement with the bittingin the group connecting the mouth branch is 5.6 ± 3.8 months; The 2 branch coapted group is the main body coapted group: 5.75 ± 0.5 months, the main body group is 5.4 ± 2.1 months. The average initial amplitude of the first commissure excursionmovement on the paralysis side is 5.4 ± 2.1 mm. The majority of patients with FNGS 2.0 results reached the grade III (70.0%). In this results table, there is 01 patient who had surgery at the age of 18 months, so he does not cooperate to move the muscle when biting with the bitting, until after 24 months he accepted to cooperate and had the oral movement. The results from 3-6 months of 06/36 patients who only sent pictures after surgery so it was only possible to identify patients who could clearly move their mouths when biting with the bitting but it is not scored according to the FNGS 2.0 score and not measured oral movement amplitude calculated from the middle of the upper lip. 3.2.2. Long term results Table 3.20.Long term results according to the House-Brackmann 2.0 score on each factor (n = 36) Characteristics Frequency (n) Proportion (%) Eyebrow (point) Mean ± SD 5.1 ± 0.8 Min – Max 3 – 6 Eye (point) Mean ± SD 1.4 ± 0.6 Min – Max 1 – 3 Nasolabial fold(point) Mean ± SD 1.2 ± 0.4 Min – Max 1 – 3 15 Mouth (point) Mean ± SD 1.3 ± 0.8 Min – Max 1 – 5 Synkinesis Mean ± SD 0.7 ± 0.5 Min – Max 0 – 2 Total points Mean ± SD 9.7 ± 2.0 Min – Max 7 – 15 Grading by point FNGS 2.0 Grade I 0 0 Grade II 24 66,7 Grade III 9 25.0 Grade IV 3 8.3 Grade V 0 0 Grade VI 0 0 Remark: After surgery 6-72 months, the majority of patients had the surgery result of grade II (66.7%); then grade III (25.0%); only 8.3% of patients had a result of grade IV. Figure 3.1. The long term result according to the classification of the studies Remark: According to the grading standard of the studies, the patients with grade I results were very good, accounting for 38.9% and good for 27.8%, only 8.3% of the patients had the average grade IV results. Grade I: Very good Grade II: Good Grade III: Fairly 16 Figure 3.2. Change of FNGS 2.0 before and after surgery Remark: Before surgery, patients with grade VI are accounted for 72.2%, grade V for 16.7% and grade IV for 11.1%. 3-6 months after surgery, patients with grade IV are accounted for 70.0%, grade V l for 16.7% and grade III for 13.3%. 6-72 months after surgery, patients with grade II are accounted for 66.7%, grade III for 25.0% and grade IV for 8.3%. Grade I Grade II Grade III Grade VI Before surgery Recent results Long term results 17 Chapter 4 DISCUSSION 4.1. Masseter muscle anatomy Through our studies of over 22 fresh corpse specimens of Vietnamese people, masseter muscle anatomy has a length of 64.4 mm, width of 37.4 mm, masseter muscle divided into 03 classes. According to Hwang's studies with 96 specimens that had a masseter muscle length of 66 ± 5.6 mm. In the studies, we did not measure the length of MN but only measured the distance from the Sigma hollow of 5.8 ± 0.8 mm to the point of branding under MN, because this is the point that we choose and cut MN inferior branch to joint microsurgery. We also measured the distance from the jaw corner to the subdivision point under MN of 48.7 ± 16.9 mm (Table 3.4), compared with Hwang's result from the jaw corner to the lower branch of 3.2 ± 4.1 mm. Brenner and Schoeller studied on more than 36 cadaver specimens and summarized that when MN entered the muscle, divided into 2 branches, is seen in 47% of the specimens, only 1 branch is seen in 5% of the specimen, 3 branches seen in 25%, 2, 8% is divided into 4 branches. Cotrufo et al only saw 02 anatomical changes: only 1 branch in 14/17 specimens, 2 branches found in 3/17 specimens. In addition, more than 96 corpse specimens of Kun Hwang and colleagues are divided into 03 anatomical changes: 1 branch, 2 branches and 3 branches. According to our analysis results: 20/22 specimens had 2 branches, 02/22 had a branch. Thus, most of the results according to reports are mainly MN divided into two upper branch and lower branch. This anatomical feature is quite important because based on this result, we often choose the nerve lower branch, used to joint microsurgery to the oral branch to 18 recover MN because this branch usually has large size and length. . According to our analysis on 22 MN specimens located at the depth layer of the masseter muscle, this is different from the author Hwang when he found MN in the middle layer and the deep layer of the masseter muscle. This difference may be due to the muscle layers division of the two different studies. The distance from the tragus to the position where the branch under MN was found according to our researches does not have a difference in the two sexes: the average in women is 33.3 mm, in men is 33.16 mm. The study of Cotrufo et al was: 26, 5 mm in men and 20.2 mm in women. This is a quite important point to relatively determine the good position of the MN inferior branch. We also obtained the same results when operatingthe patients in fact. Therefore, when clinically apply we also marked this position and draw line parallel to the tragus and about 33 mm from here on the patient to locate MN. Through the surgery on 22 specimens, we found that the zygoma and the buccalbranches on the nerve VII, created the upper limit and lower limit, which is very important for determining the MN inferior branch. In Bermudez's studies, the author identifiedMN by looking for zygomabranch and operating the masseter muscle under this branch to find the nerve. The author Cotrufo determined by square drawn on the skin with the points includingZygoma arch,tragus,buccal branch. However, we find that this determination is still quite difficult because when operating the patients, we are forced to peel off the skin layer so thesepoints on the skin will be very difficult to compare. We found that during surgery for coapted the nerve VII, surgeons often have to find the oral branch of the nerve VII, the more accurate identification of thisdonor nerve can be usednervous stimulation pen. 19 Therefore, we consider this as the lower limit, while the zygomaticbranchis the upper limit, with the line parallel to the tragus and about 33.2 mm from the tragus. Through this diagram, we found MN in the deep layer of masseter muscle on 22 specimens. The determination of this diagram is also studied when we operate on patients (please refer to the surgical section). The diameter we measured on the corpse specimens between the two ends of the nerve, the oral branch and MN,is relatively similar: 1.1 mm and 1.2 mm. In previous studies by foreign authors, we do not see the presentation of MN headdiameter, although this is also an important factor in nervouscoapted technique. However, in clinical practice we found that the MN inferior branch is always very small and there is only one nervousfiber bundle so we try to joint all nervous fiber bundles of the nerve VII branches or the suralnerve with the fiber bundle of MN inferior branch. 4.2. Surgical results 4.2.1. Short-term results Our assessment of recent postoperative results is based on the time of the time onset of vibrationafter surgery, the time of the first commissure excursion movement at paralysis side after surgery with the bitting, the amplitude of the first movement at paralysis side, compared with the healthy side and FNGS 2.0 score. According to Murphey, in 10 articles, the time of the time onset of vibrationin themain body coaptedgroup were 5.76 months on average, while in the branchcoapted group it was 3.76 months. Therefore, we choose the time to evaluate the recent results for 3-6 months after surgery. In our studies, the time of the time onset of vibrationof the buccal branchcoapted patient was 3.5 months, of the two branchcoapted was 4.3 months, of the main body was 4.6 months.Compared with some other authors, we have the average 20 time of the time onset of vibrationsimilar to results of other authors. The authors Biglio and Bianchi do not join the branch VII directly to the MN branch but join nerve roots through a compound. According to the author Bianchi, this is why the time for neurotransmitter recovery is longer (8 months). In our patients group, there were 05 patients who were joined to the original of the nerve VII with the average initial muscle vibration time of 4.6 months in accordance with the author Biglio. This shows that the axons regeneration ability of MN wire is very high. In another studies, the comparison of the neurotransmitter group XII and MN for the nerve VII of the author Hontanilla showed that the transmission recovery time of MN averaged 62 days, while that of the nerve XII was 136 days. The early recovery time of the nerve VII after MN transfer helps to reduce facial area muscle degeneration, to increase the results of movement recovery. As the medical literature has shown, before being used as a major nerve for transmission recoveryof the nerve VII, MN has been used as a support nerve (babysitter) while waiting for facial nerves that continued to transmit. The average time of the first commissure excursion movement in our studies in coaptedbuccal branch group is 5.6 months, 5.75 months for the two branch coapted group and 5.4 months for the main bodycoapted group. According to Wang's report, this time is 6 months, Klebuc is 5.6 months. We found that from the time we saw the time onset of vibrationuntil the patient clearly and well movecommissure excursion with the bitting, it is quite fast with 1 month on the average. This suggests that if there is a neurotransmitter, the nervous movement recoveryappears and the movements will be performed. 21 The paralysis grading according to the FNGS 2.0 score of the recent results in our patients group who reached grade III for 70%; grade II for 13.3%; grade IV for 16. 7%. The average amplitude of commissure excursionvibration at 3-6 months after surgery in our studies was 5.6 mm. According to Hontanilla's studies, it was 7.8 mm. Many authors do not measure the oral movement amplitude calculated from the upper lip middle at the beginning but usually after 6-12 months of surgery when the muscles are strong and clear. According to the score, we found that the mouth branch was restored to its earliest transmission, followed by the zygoma and eyehole branches. The patient will have the first commissure excursionmovement and then close his eyes. Many authors share the same comments with us,Biglio found that the first visible nervous movement recovery is from large zygoma muscle. The reason for this result has not yet been shown by any author, but in our opinion, the mouth branch and the zygomaand eyehole branches are usually large and are connected in the branches VII and dominate many facial muscles so when recovering the nerve is usually faster than other branches. 4.2.2. Long-term results Our follow-up period from a distance after surgery is from 12 to 96 months, Author Wang: 6-12 months; Klebuc: 7-84 months; Faria: 6-18 months and Bianchi: 12-72 months. For nervous transmission reconstruction surgery we find that the lon

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