Masseteric Nerve Transfer for Facial Nerve Paralysis: A Systematic Review and Meta-analysis

Masseteric-facial anastomosis and hypoglossal-facial anastomosis after lateral skull base and middle ear surgery

INTRODUCTION

Lateral skull base (LSB) and middle ear pathologies often involve the facial nerve (FN), and their treatment may require FN sacrifice. Cases with unidentifiable proximal stump or intact FN with complete FN palsy, necessitate FN anastomosis with another motor nerve in order to restore innervation to the mimicking musculature. The results of hypoglossal-to-facial nerve anastomosis (HFA) and masseteric-facial nerve anastomosis in patients with facial paralysis after middle ear and LSB surgeries, are presented and compared.

METHODS

Adult patients with total definitive facial paralysis after middle ear or LSB surgery undergoing facial nerve reanimation through hypoglossal or masseteric transfer anastomosis were enrolled. The facial nerve function was graded according to the House Brackmann grading system (HB). The facial function results at 3 months, 6 months, 12 months, 18 months and at the last follow up (more than 18 months) are compared.

RESULTS

153 cases of LSB and middle ear surgery presented postoperative facial palsy and underwent facial nerve reanimation surgery with HF in 85 patients (55.5%) and MF in 68 patients (44.5%). The duration of the FN palsy before reconstructive surgery was inversely associated to better FN results, in particular with having a grade III HB (p = 0.003). Both techniques had significantly lower HB scores when an interval between palsy onset and reanimation surgery was 6 months or less (MF p = 0.0401; HF p = 0.0022). Patients who underwent a MF presented significant improvement of the FN function at 3 months from surgery (p = 0.0078). At the last follow-up, 63.6% recovered to a grade III HB and 22.7% to a grade IV. On the other hand, the first significant results obtained in the HF group were at 6 months from surgery (p < 0.0001). 67.8% of patients had a grade III HB after a HF at the last follow-up, 28.8% a grade IV. FN grading at 6 months from surgery was significantly lower in the MF group compared to the HF (p = 0.0351). The two techniques had statistically similar results at later follow-up evaluations.

DISCUSSION/CONCLUTION

MF was associated to initial superior results, presenting significant facial recovery at 3 months, and significantly better functional outcomes at 6 months from surgery compared to HF. Although later results were not significantly different in this study, earlier results have an important role in order to limit the duration of risk of corneal exposure.

Masseteric Atrophy Following Masseteric Nerve Transfer: Radiographic Findings of Asymmetry in the Paralyzed Face?

OBJECTIVES

To characterize the effect of facial reanimation using masseteric nerve transfer on the masseter muscle itself, examining whether there is any demonstrable atrophy postoperatively.

METHODS

Electronic medical records of adult patients who underwent facial reanimation using masseteric nerve transfer at our institution over a 15-year period were reviewed. To account for the impact of postoperative radiation, randomly selected patients who underwent radical parotidectomy without nerve transfer and received postoperative radiation served as controls in a 1:1 fashion against those who underwent masseteric nerve transfer with postoperative radiation.

RESULTS

Twenty patients were identified who underwent masseteric nerve transfer and had sufficient pre- and postoperative imaging to assess masseter volume (mean age 58.2, 60% female). Of the four patients who did not receive postoperative radiation, each demonstrated masseteric atrophy on the side of their nerve transfer, with a mean reduction in masseter volume of 20.6%. The remaining 16 patients were included in the case-control analysis accounting for radiation. When compared with controls, those in the study group were found to have a statistically significant difference in atrophy (p = 0.0047) and total volume loss (p = 0.0002). The overall reduction in masseter volume in the study group was significantly higher compared with the control group, at 41.7% and 16.6%, respectively (p = 0.0001).

CONCLUSION

Facial reanimation utilizing masseteric nerve transfer appears to result in atrophy of the denervated masseter when compared with the contralateral muscle. This volume deficit may lead to further facial asymmetry for patients undergoing comprehensive reanimation surgery.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:4514-4520, 2024.

Deep masseteric triangular area to define masseter neurovascular bundle: A cadaveric study

INTRODUCTION

Facial reanimation procedures are used in the treatment of the disorder that impairs mimetic function and jeopardizes physical and psychological health, and one of the most important instruments of these techniques is the masseteric neurovascular bundle (NVB) and proper identification at the mandibular notch level. In the current study, a triangular area (deep masseteric triangle, DMT) on the lateral surface of the masseter muscle that was identified to help reliable determination of the masseteric NVB at the mandibular notch level.

MATERIAL AND METHODS

40 parotideomasseteric region dissections were performed in 10 female and 10 male donated cadavers. Structures lateral to the masseter muscle were removed. The edge length of the masseter muscle on the zygomatic arch side was measured. After the edges of the DMT were measured, the masseteric NVB was found by dissection and its distance (depth) from the skin line was measured.

RESULTS

The mean lengths of the superior, posterior, and anterior margins were 17.3 (±4.5) mm, 25.9 (±6.2) mm, and 26.3 (±6.5) mm, respectively. The total length of the upper edge of the masseteric muscle attached to the zygomatic arch averaged 52.7 (±5.2) mm. The masseteric neurovascular bundle was detected at a depth of approximately 17 mm from the skin of the parotideamasseteric region.

DISCUSSION

The visualization of the DMT can be used as an important landmark for access to branch-free part of the masseteric nerve. Moreover, an specific approach for masseteric NVB localization can be established by drawing a line between the mandibular angle and the midpoint of the upper edge of the DMT. This technique can greatly improve the accuracy of both masseteric nerve harvesting and masseteric nerve block procedures.

[Anatomical Identification and Possibilities of Transfer of the Masseteric Nerve for Facial Reanimation]

BACKGROUND

The masseteric nerve (MN) is often used as a donor nerve for facial reanimation. In addition to already established techniques, MN transfer is rapidly gaining importance, mainly due to the single-stage approach of the procedure and its reconstructive potential. This anatomical study and the associated questionnaire study aimed to evaluate the established methods for identification of the MN and its suitability for direct nerve transfer as well as to assess the importance of MN transfer in the daily clinical routine.

MATERIAL AND METHODOLOGY

Bilateral dissection of 25 fresh-frozen head specimens (n=50; 13 female, 12 male) was performed with accompanying measurement of the MN. In a questionnaire study conducted at established centres for facial surgery in German-speaking countries, clinical experience data of MN transfer was collected using the SurveyMonkey software. The data obtained was statistically analysed using Microsoft Excel and presented in numerical tables and boxplots.

RESULTS

Using anatomical landmarks such as the zygomatic arch and the mandibular notch for orientation, the MN was found in 100% of cases. Its average length from the emerging point below the zygomatic arch towards its entry into the masseter muscle was measured to be 22 mm and was the length available for nerve transposition. Tension-free coaptation of the MN with the zygomatic branch was possible in 94% of cases. The questionnaire showed that the MN is considered an important donor nerve for motor nerve transfers and that MN transfer is now largely established as a standard procedure.

DISCUSSION

In accordance with previously published studies, the MN was reliably found at the height of the mandibular notch and, in the vast majority of cases, was suitable for tension-free coaptation with the zygomatic branch. Differences to the existing literature, however, can be seen in the length of the nerve available for nerve transposition and the frequency of its division into several branches before entering the masseter muscle. In German-speaking countries, Cross-Face Nerve Grafting (CFNG) is still the preferred method for facial reanimation surgery. However, MN transfer is also well established by now, both as an alternative and a supplement to other techniques, possibly due to its low donor site morbidity and short time to regeneration.

Facial nerve reconstruction for flaccid facial paralysis: a systematic review and meta-analysis

Objectives

To determine the functional outcome after facial nerve reconstruction surgery in patients with flaccid facial paralysis.

Methods

A systematic review and meta-analysis was performed on studies reporting outcomes after direct facial nerve suture (DFS), facial nerve interpositional graft suture (FIGS), hypoglossal-facial nerve suture (HFS), masseteric-facial nerve suture (MFS), and cross-face nerve suture (CFS). These studies were identified from PubMed/MEDLINE, Embase, and Web of Science databases. Two independent reviewers performed two-stage screening and data extraction. A favorable result was defined as a final House-Brackmann grade I-III and is presented as a ratio of all patients in percentage. Pooled proportions were calculated using random-effects models.

Results

From 4,932 screened records, 54 studies with 1,358 patients were included. A favorable result was achieved after DFS in 42.67% of the patients [confidence interval (CI): 26.05%-61.12%], after FIGS in 66.43% (CI: 55.99%-75.47%), after HFS in 63.89% (95% CI: 54.83%-72.05%), after MFS in 63.11% (CI: 38.53%-82.37%), and after CFS in 46.67% (CI: 24.09%-70.70%). There was no statistically significant difference between the techniques (Q = 6.56, degrees of freedom = 4, p = 0.1611).

Conclusions

The established facial nerve reconstruction techniques including the single nerve cross-transfer techniques produce satisfactory results in most of the patients with permanent flaccid facial paralysis. An international consensus on standardized outcome measures would improve the comparability of facial reanimation techniques.

Masseteric Nerve Ultrasound Identification for Dynamic Facial Reanimation Purposes

BACKGROUND

The masseteric nerve is one of the main options to neurotize free muscle flaps in irreversible long-term facial paralysis. Several preoperative skin-marking techniques for the masseteric nerve have been proposed to limit the surgical dissection area, shorten the surgical time, and enable a safer dissection. However, these have shown variability among them, and cannot visualize the nerve preoperatively. The authors designed an observational study to validate a high-frequency ultrasound (HFUS) nerve identification technique.

METHODS

A systematic HFUS examination was designed and performed to visualize the masseteric nerve in 64 hemifaces of healthy volunteers. One-third were randomly selected to undergo an additional HFUS-guided needle electrostimulation to validate the HFUS image.

RESULTS

The masseteric nerve was identified by HFUS in 96.9% of hemifaces (95% CI, 0.89 to >0.99) and showed almost perfect agreement with direct needle stimulation as calculated with Cohen kappa coefficient (0.95; 95% CI, 0.85 to 1.00). The masseteric nerve was found within the masseter muscle, in between the deeper muscle bellies, at 18.3 mm (SD ±2.2) from the skin. Only in 12.9% of cases (95% CI, 0.06 to 0.24) did its course become adjacent to the mandible periosteum. Other important features, such as disposition in relation to the parotid gland, or if the nerve was covered directly by a thick intramuscular aponeurosis, could be well observed by HFUS.

CONCLUSION

HFUS enables masseteric nerve identification and can provide the surgeon with specific information on anatomical relations for each examined individual before surgery.

Task force of the Brazilian Society of Otology - evaluation and management of peripheral facial palsy

OBJECTIVE

To review key evidence-based recommendations for the diagnosis and treatment of peripheral facial palsy in children and adults.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on peripheral facial palsy were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 main parts: (1) Evaluation and diagnosis of facial palsy: electrophysiologic tests, idiopathic facial palsy, Ramsay Hunt syndrome, traumatic peripheral facial palsy, recurrent peripheral facial palsy, facial nerve tumors, and peripheral facial palsy in children; and (2) Rehabilitation procedures: surgical decompression of the facial nerve, facial nerve grafting, surgical treatment of long-term peripheral facial palsy, and non-surgical rehabilitation of the facial nerve.

CONCLUSIONS

Peripheral facial palsy is a condition of diverse etiology. Treatment should be individualized according to the cause of facial nerve dysfunction, but the literature presents better evidence-based recommendations for systemic corticosteroid therapy.

Masseteric Nerve Transfer for Facial Paralysis Secondary to Parotid Malignancy: A Retrospective Case Series

Background: The objective outcomes of masseteric nerve transfer in the setting of parotid malignancy are unclear. Objective: To measure objective facial reanimation outcomes of masseteric nerve transfer in patients with parotid malignancy who underwent parotidectomy with facial nerve resection. Materials and Methods: Retrospective review of patients who underwent masseteric nerve transfer for facial paralysis secondary to parotid malignancy was carried out at a tertiary referral hospital from August 2017 to November 2021. Objective facial reanimation outcomes were analyzed using Emotrics. Minimal follow-up of 6 months was required for inclusion. Results: Eight patients (five males) with a median age of 75.5 years (range 53-91) met inclusion criteria. Fifty percent had metastatic squamous cell carcinoma, and 50% had primary parotid malignancy. Five patients underwent concomitant cancer resection with facial nerve reconstruction. Seven patients received postoperative adjuvant radiotherapy. After reinnervation, patients had improved oral commissure excursion (from 1.51 mm ±1.27 to 3.77 mm ±1.81; p < 0.01) and facial symmetry during smile. Conclusion: In this study, masseteric nerve transfer enhanced oral commissure excursion and facial symmetry during smile in patients with parotid malignancy and facial nerve resection.

An ACS-NSQIP Data Analysis of 30-Day Outcomes Following Surgery for Bell's Palsy

BACKGROUND

There exists a paucity of large-scale, multi-institutional studies that investigate the outcomes of surgery for Bell's palsy (BP). Here, we utilize a large, multi-institutional database to study the risk factors and early-stage outcomes following surgical procedures in BP.

METHODS

We reviewed the American College of Surgeons National Surgical Quality Improvement Program database (2008-2019) to identify patients who underwent surgery for the diagnosis of BP. We extracted data on comorbidities and preoperative blood values, and 30-day postoperative outcomes.

RESULTS

Two hundred fifty-seven patients who underwent surgery for BP symptoms over the 12-year review period were identified. Muscle grafts (n=50; 19%) and fascial grafts (n=48; 19%) accounted for the majority of procedures. The most common comorbidities were hypertension (n=89; 35%) and obesity (n=79; 31%). Complications occurred in 26 (10.1%) cases. Additionally, length of hospital stay was significantly associated with both surgical and medical complications (3.9±4.7 versus 1.5±2.0; P <0.01) and (3.2±3.8 versus 1.4±2.0; P <0.01), respectively. Preoperative creatinine, blood urea nitrogen, and alkaline phosphatase were identified as potential predictors of poor postoperative outcomes.

CONCLUSION

Based on multi-institutional analysis, complication rates following surgery for BP were found to be overall low and seen to correlate with length of hospital stay. Reoperations and readmissions were the most frequent complications after surgery for BP. The preoperative evaluation of routine laboratory values may help refine patient eligibility and risk stratification. In addition, our findings call for future large-scale prospective studies in the field of facial palsy surgery to further improve the quality of care and optimize perioperative protocols.

The masseteric nerve for facial reanimation: Macroscopic and histomorphometric characteristics in 106 human cadavers and comparison of axonal ratio with recipient nerves

Peripheral facial palsy causes severe impairments. Sufficient axonal load is critical for adequate functional outcomes in reanimation procedures. The aim of our study was to attain a better understanding of the anatomy of the masseteric nerve as a donor, in order to optimize neurotization procedures. Biopsies were obtained from 106 hemifaces of fresh frozen human cadavers. Histological cross-sections were fixed, stained with PPD, and digitized. Histomorphometry and a validated software-based axon quantification were conducted. Of the 154 evaluated branches, 74 specimens were of the main trunk (MT), 40 of the anterior branch (AB), and 38 of the descending branch (DB), while two halves of one cadaver featured an additional branch. The MT showed a diameter of 1.4 ± 0.41 mm (n = 74) with 2213 ± 957 axons (n = 55). The AB diameter was 0.9 ± 0.33 mm (n = 40) with 725 ± 714 axons (n = 30). The DB diameter was 1.15 ± 0.34 mm (n = 380) with 1562 ± 926 axons (n = 30). The DB demonstrated a high axonal capacity - valuable for nerve transfers or muscle transplants. Our findings should facilitate a balanced selection of axonal load, and are potentially helpful in achieving more predictable results while preserving masseter muscle function.

Novel Method of Dual-innervated Free Gracilis Muscle Transfer for Facial Reanimation: A Case Series

Background

Dynamic facial reanimation is the gold standard treatment for a paralyzed face. The use of the cross-face nerve graft (CFNG) in combination with the masseteric nerve to innervate the free gracilis muscle has been reported to provide both spontaneity and strong neural input. We report a case series of dual innervation, using a novel method where the branch to masseter is coapted to the side of the CFNG.

Methods

Eight patients received free gracilis muscle transfer using the new dual innervation method between September 2014 and December 2017. The CFNG, which was performed nine months prior, was sutured in an end-to-end fashion to the obturator nerve. A nerve graft was coapted to the ipsilateral masseteric nerve and then sutured in an end-to-side fashion to the CFNG proximal to its coaptation to the obturator nerve.

Results

All patients recovered smile function with and without teeth clenching around the same time period. Smiles without teeth clenching appeared later in two of eight patients and earlier in one of eight patients, being noted at an average of 8.25 months of follow-up versus 7.6 months. The estimate of true attainment is limited by the spacing of follow-up dates. Average follow-up time was 36.07 months (range: 10-71.5). FACE-Gram software smile analysis with and without biting demonstrated similar excursion on average (7.64 mm versus 8.6 mm respectively, P = 0.93), both of which are significantly improved from preoperation.

Conclusion

This novel method of a dual-innervated free gracilis muscle transfer offers a viable technique that achieves a symmetric, strong, and emotional smile.

Research trends and perspectives on immediate facial reanimation in radical parotidectomy (Review)

For patients diagnosed with advanced malignant parotid tumour, radical parotidectomy with facial nerve sacrifice is part of the treatment. Multiple surgical techniques have been developed to cure facial paralysis in order to restore the function and aesthetics of the face. Despite the large number of publications over time on facial nerve reanimation, a consensus on the timing of the procedure or the donor graft selection has remained to be established. Therefore, the aim of the present study was to conduct a bibliometric analysis to identify and analyse scientific publications on the reconstruction of the facial nerve of patients who underwent radical parotidectomy with facial nerve sacrifice. The analysis on the topic was conducted using the built-in tool of the Scopus database and VOSviewer software. The first 100 most cited articles were separately reviewed to address the aim of the study. No consensus was found regarding the recommended surgical techniques for facial nerve reanimation. The most used donor cranial nerves for transfer included the following: Masseteric branch of the V nerve, contralateral VII nerve with cross-face graft, the XI nerve and the XII nerve. The best timing of surgery is also controversial depending on pre-exiting pathology and degree of nerve degeneration. However, most of the clinical experience suggests facial nerve restoration immediately after the ablative procedure to reduce complications and improve patients' quality of life.

Nerve guide conduits, nerve transfers, and local and free muscle transfer in facial nerve palsy

PURPOSE OF REVIEW

To highlight the recent literature on reinnervation options in the management of facial nerve paralysis using nerve conduits, and nerve and muscle transfers.

RECENT FINDINGS

Engineering of natural and synthetic nerve conduits has progressed and many of these products are now available on the market. The use of the masseter nerve has become more popular recently as a choice in nerve transfer procedures due to various unique advantages. Various authors have recently described mimetic muscle reinnervation using more than one nerve transfer, as well as dual and triple innervation of free muscle transfer.

SUMMARY

The ideal nerve conduit continues to be elusive, however significant progress has been made with many natural and synthetic materials and designs tested and introduced on the market. Many authors have modified the classic approaches in motor nerve transfer, as well as local and free muscle transfer, and described new ones, that aim to combine their advantages, particularly the simplification to a single stage and use of multiple reinnervation to the mimetic muscles. These advances are valuable to the reconstructive surgeon as powerful tools that can be tailored to the unique challenges of patients with facial nerve palsy looking for dynamic reanimation options.

The Selective Trigeminal Nerve Motor Branching Transfer: an Preliminary Clinical Application for Facial Reanimation

OBJECTIVE

To investigate the effectiveness and feasibility of selective trigeminal nerve motor branching in the repair of facial palsy.

MATERIALS AND METHODS

The clinical data of patients with advanced facial palsy from 2016 to 2021 were retrospectively analyzed, including pictures and videos before and 18 months after surgery. The House-Brackmann grading system was used to evaluate facial nerve function before and after repair, and the symmetry scale of oral commissure at rest and Terzis' smile functional evaluation scale were used to qualitatively assess the symmetry of the mouth angle and smile function. The distance of oral commissure movement was assessed to evaluate the dynamic repair effect, and the FaCE facial muscle function scale was used to assess patients' subjective perception before and after surgery.

RESULTS

A total of four patients were included in the study, all of whom showed signs of recovery of facial nerve function within six months. In all four cases, significant improvements were observed in House-Brackmann ratings, the smile function score and the symmetry scale of oral commissure at rest. Compared to the pre-operative period, the four patients demonstrated various degrees of eye-closing function recovery, and a significant improvement in oral commissure movement was observed ( P <0.001). FaCE scores also improved significantly after surgery ( P =0.019).

CONCLUSION

Concurrent selective facial nerve repair with trigeminal branch-facial nerve anastomosis resulted in eye-closing function recovery while improving static and dynamic symmetry, yielding acceptable postoperative results.

Anatomic Analysis of Masseteric-to-zygomatic Nerve Transfer in Rat and Pig Models

Background

Nerve transfer from the masseteric branch of the trigeminal nerve is a widely performed procedure for facial reanimation. Despite achieving powerful muscle force, clinical and aesthetic results leave room for improvement. Preclinical animal models are invaluable to establishing new therapeutic approaches. This anatomical study aimed to establish a masseteric-to-zygomatic nerve transfer model in rats and pigs.

Methods

The masseteric branch of the trigeminal nerve and the zygomatic branch of the facial nerve were dissected in 30 swine and 40 rat hemifaces. Both nerves were mobilized and approximated to achieve an overlap between the nerve ends. Over the course of dissecting both nerves, their anatomy, length, and branching pattern were documented. At the coaptation point, diameters of both nerves were measured, and samples were taken for neuromorphometric analysis.

Results

Anatomic details and landmarks were described. Tension-free coaptation was possible in all rat and pig dissections. In rats, the masseteric branch had an average diameter of 0.36 mm (±0.06), and the zygomatic branch average diameter was 0.46 mm (±0.13). In pigs, the masseteric branch measured 0.52 (±0.16) mm and the zygomatic branch, 0.59 (±0.16) mm. No significant differences were found between the diameters and axon counts of both nerves in pigs. In rats, however, their diameters, axon counts, and fascicular areas were significantly different.

Conclusion

Our study demonstrated the feasibility of direct masseteric-to-zygomatic nerve transfer in rats and pigs and provided general anatomic knowledge of both nerves.

Evidence-Based Practices in Facial Reanimation Surgery

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Describe the causes and preoperative evaluation of facial paralysis. 2. Discuss techniques to restore corneal sensation and eyelid closure, elevation of the upper lip for smile, and depression of the lower lip for lip symmetry. 3. Outline treatment goals, surgical treatment options, timing of repair, and other patient-specific considerations in appropriate technique selection.

SUMMARY

Congenital facial paralysis affects 2.7 per 100,000 children; Bell palsy affects 23 per 100,000 people annually; and even more people are affected when considering all other causes. Conditions that impair facial mimetics impact patients' social functioning and emotional well-being. Dynamic and static reconstructive methods may be used individually or in concert to achieve adequate blink restoration, smile strength and spontaneity, and lower lip depression. Timing of injury and repair, patient characteristics such as age, and cause of facial paralysis are all considered in selecting the most appropriate reconstructive approach. This article describes evidence-based management of facial paralysis.

Advances in Facial Reanimation

Facial nerve paralysis is a debilitating clinical entity that presents as a complete or incomplete loss of facial nerve function. The etiology of facial nerve palsy and sequelae varies tremendously. The most common cause of facial paralysis is Bell's palsy, followed by malignant or benign tumors, iatrogenic insults, trauma, virus-associated paralysis, and congenital etiologies.

The Role of the Cross Face Nerve Graft in Facial Reanimation and Endoscopic Harvest of the Sural Nerve

Cross-face nerve grafting (CFNG) allows for spontaneous, involuntary facial movement for patients with irreversible hemifacial paralysis. This technique uses an intact contralateral facial nucleus and nerve as an input and axon source, allowing donor neural input to be routed through a nerve graft across the face. The sural nerve is well equipped for use as a nerve graft due to its length and minimal donor site morbidity. Endoscopic nerve harvest techniques allow for efficient, minimally invasive dissection that improves the integrity of the harvested nerve.

Early Simultaneous Cross Facial Nerve Graft and Masseteric Nerve Transfer for Facial Paralysis after Tumor Resection

We describe a new approach for facial reanimation after skull base tumor resection with known facial nerve sacrifice, involving simultaneous masseter nerve transfer with selective cross facial nerve grafting (CFNG) within days after tumor surgery. This preliminary study compared outcomes of this approach versus a staged procedure involving a masseter nerve "babysitter" performed in a delayed timeline.

Methods

Patients undergoing masseter nerve transfer and CFNG for facial paralysis after skull base tumor resection were consented to participate in video interviews. Facial Clinimetric Evaluation (FaCE) Scale (0-100) patient-reported outcome, eFACE, and Facial Grading Scale scores were compared.

Results

Nine patients had unilateral facial paralysis from resection of a schwannoma (56%), acoustic neuroma (33%), or vascular malformation (11%). Five underwent early simultaneous CFNG and masseter nerve transfer (mean 3.6 days after resection), whereas four underwent two-stage reanimation including a babysitter procedure (mean 218 days after resection). Postoperative FaCE scale and Facial Grading Scale scores were similar in both groups (P > 0.05). Postoperative mean eFACE scores were similar for both groups for smile (early: 71.5 versus delayed: 75.5; P = 0.08), static (76.3 versus 82.1; P = 0.32), and dynamic scores (59.7 versus 64.9; P = 0.19); however, synkinesis scores were inferior in the early group (76.4 versus 91.1; P = 0.04).

Conclusions

Early simultaneous masseter nerve transfer and CFNG provides reanimated movement sooner and in fewer stages than a staged approach in a delayed timeline. The early technique appears to result in similar clinician- and patient-reported outcomes compared with delayed procedures; however, in this preliminary study, the early approach was associated with greater synkinesis, meriting further investigation.

MODIFIED GRACILIS MUSCLE FLAP IN FACIAL REANIMATION: U-SHAPED DESIGN

BACKGROUND

Surgical treatment of long-term facial palsy has been reported using various techniques, including functioning muscle-free flaps. The free gracilis muscle flap is the most common because of its many advantages. Our study presents a modified way of shaping the gracilis muscle for transfer to the face to improve the restoration of natural smiles.

METHODS

This retrospective study assessed 5 patients who received the classical technique and 43 patients who received modified, U-shaped, free gracilis muscle flap for smile reanimation from 2013 to 2018. The surgery is single-staged. Preoperative and postoperative photos were taken. Functional outcomes were evaluated using the Terzis and Noah score and the Chuang smile excursion score.

RESULTS

The mean patient age at the time of operation was 31 years. The length of gracilis muscle harvested was 12-13 cm. Of the 43 patients who received U-shaped design-free gracilis muscle, results were excellent for 15 (34.9%), good for 20 (46.5%), and fair for 8 (18.6%) followed the Terzis and Noah score. The Chuang smile excursion score was 2 for 16.3%, 3 for 46.5%, and 4 for 37.2% of 43 patients. Of the 5 patients who underwent classical technique, there are no excellent results based on the Terzis and Noah score. The Chuang smile excursion score was only 1 and 2.

CONCLUSIONS

The U-shaped modification to the gracilis muscle-free flap is a simple and effective technique to help restore a symmetrical and natural smile in patients with facial palsy.

Smile Reanimation with Masseteric-to-Facial Nerve Transfer plus Cross-Face Nerve Grafting in Patients with Segmental Midface Paresis: 3D Retrospective Quantitative Evaluation

Facial paresis involves functional and aesthetic problems with altered and asymmetric movement patterns. Surgical procedures and physical therapy can effectively reanimate the muscles. From our database, 10 patients (18–50 years) suffering from unilateral segmental midface paresis and rehabilitated by a masseteric-to-facial nerve transfer combined with a cross-face facial nerve graft, followed by physical therapy, were retrospectively analyzed. Standardized labial movements were measured using an optoelectronic motion capture system. Maximum teeth clenching, spontaneous smiles, and lip protrusion (kiss movement) were detected before and after surgery (21 ± 13 months). Preoperatively, during the maximum smile, the paretic side moved less than the healthy one (23.2 vs. 28.7 mm; activation ratio 69%, asymmetry index 18%). Postoperatively, no differences in total mobility were found. The activity ratio and the asymmetry index differed significantly (without/with teeth clenching: ratio 65% vs. 92%, p = 0.016; asymmetry index 21% vs. 5%, p = 0.016). Postoperatively, the mobility of the spontaneous smiles significantly reduced (healthy side, 25.1 vs. 17.2 mm, p = 0.043; paretic side 16.8 vs. 12.2 mm, p = 0.043), without modifications of the activity ratio and asymmetry index. Postoperatively, the paretic side kiss movement was significantly reduced (27 vs. 19.9 mm, p = 0.028). Overall, the treatment contributed to balancing the displacements between the two sides of the face with more symmetric movements.

Laryngeal reinnervation for paediatric vocal cord palsy: a systematic review

OBJECTIVE

This systematic review aims to provide an overview of the current evidence-base for paediatric surgical reinnervation in unilateral and bilateral vocal fold palsies in clinical practice. We aim to assess patient demographics, surgical technique and pre- and post-operative outcome measures.

METHODS

A systematic literature review was performed and reported according to international PRISMA recommendations. A comprehensive search of PubMed, Embase, and Cochrane CENTRAL databases for relevant publications for all available dates with appropriate MESH search criteria was performed. Articles were categorised by four authors independently. A pooled summative analysis was carried out to allow review of demographic and outcome data.

RESULTS

Our systematic PRISMA approach resulted in 19 papers being selected for inclusion and analysis with 179 patients undergoing reinnervation (153 unilateral, 26 bilateral). The youngest patient was 1.9 years. Iatrogenic injury to recurrent laryngeal nerve most common aetiology (65.4% and 19.2% of unilateral and bilateral vocal fold palsies, respectively). Patent ductus arteriosus ligation was the single most common procedure resulting in unilateral vocal fold palsies (43.1% of cases). Statistically significant improvements in subjective and objective outcomes for both voice and swallowing were seen. Meta-analysis was able to be performed on the particularly evident improvements in GRBAS score and Maximum Phonation Time (MPT). GRBAS scores improved by 3.64 (p < 0.01, 95% CI 2.65 to 4.63). MPT showed a statistically significant improvement of 5.26 s (p < 0.05, 95% CI 4.28 to 6.24). No major complications were reported.

CONCLUSION

The current published evidence on one-hundred and seventy-nine paediatric surgical reinnervation procedures demonstrates its role as a safe and effective treatment for both unilateral and bilateral vocal fold palsies. Anatomically it has been shown to improve vocal fold tone, bulk and position. Both post-operative voice and swallowing outcomes show improvement as well as associated quality of life measures.

Masseteric-to-facial nerve transfer for treatment of pediatric facial paralysis: An initial report

OBJECTIVES

The indications and outcomes of masseteric-to-facial nerve transfer in pediatric patients with short-term facial paralysis is incompletely understood as compared to its use in adult patients. This report aims to retrospectively quantify outcomes with both clinician-based measurements and objective facial analysis software.

METHODS

Retrospective case series at a single institution. The Sunnybrook Facial Grading System was used for clinician-based measurements and Emotrics software for objective measurements.

RESULTS

Four pediatric patients underwent masseteric-to-facial nerve transfers from 2016 to 2018. The mean patient age at the time of surgery was 4.5 years (range = 2-7) and the mean time from paralysis onset to surgical intervention was 12.9 months (range = 10.0-16.2). The mean follow-up was 18.3 months (range = 14.5-23.6). With regards to the Sunnybrook resting nasolabial fold symmetry, 3 of the 4 patients improved from 2 (absent nasolabial fold) to 1 (less pronounced nasolabial fold). Per the Emotrics analysis, the pre- and post-operative mean absolute differences for commissure excursion between the normal functioning and paralyzed sides were 11.8 mm and 6.7 mm, respectively (p = 0.04).

CONCLUSION

The masseteric-to-facial nerve transfer technique leads to an objective improvement in dynamic smile function in select pediatric patients.

Supercharging the Smile: A Novel Dual Nerve Transfer for Facial Reanimation

Facial paralysis has profound effects on the functional and psychosocial well-being of patients. Various surgical facial reanimation techniques have been described to address this devastating condition. While traditional surgical approaches have proved successful in restoring either facial tone or facial movement, newer combination nerve transfer techniques are addressing the limitations of the traditional single nerve transfer approaches.

[Dynamic procedures for facial nerve reconstruction]

In this article the indications and surgical treatment options for patients with facial nerve palsy are discussed. A distinction is made between static and dynamic surgical procedures. Static reconstructions for example are used to restore the eyelid closure function. For smile reconstruction, which is important for the psychosocial life of the patient, dynamic procedures are used. Depending on the duration of the facial nerve paralysis, there are several possibilities to restore the smile. In this work the masseteric branch transposition to the buccal branch, the hypoglossal-facial nerve anastomosis, the Labbé procedure and the gracilis flap as a free muscle transplant are discussed. The surgical procedures are compared and the advantages and disadvantages of the intervention are presented. A spontaneous smile is aimed, this cannot always be achieved. With the masseteric branch transposition to the buccal branch and the Labbé procedure the smile is initially triggered by chewing. A spontaneous smile is possible through cortical adaptation. With the gracilis flap, however, a nerve anastomosis with the contralateral 'healthy' facial nerve is possible, either directly or via a so-called cross facial nerve grafting, whereby a spontaneous smile can be achieved.

Anatomic Considerations of Perinasal Musculature for Improved Dental Show During Smile in Facial Synkinesis

Introduction:

There is an anatomic explanation for upper lip and midfacial tethering resulting in lack of motion in facial synkinesis.

Objective:

To measure the effect of perinasal chemodenervation on dental show in the synkinetic population and clarify the anatomic relationship of perinasal musculature.

Methods:

Literature search was performed on anatomy of the perinasal modiolus, and anatomic evaluation was performed through human anatomic specimen dissection. Photographic outcomes were observed in synkinetic patients receiving chemodenervation to smile antagonists with and without perinasal muscle injections and assessed through naive observer survey. Retrospective outcomes for all patients receiving perinasal chemodenervation was collected utilizing Facial Clinimetric Evaluation Scale, Sunnybrook Facial Grading System (FGS), Facial Disability Index (FDI), and the Synkinesis Assessment Questionnaire.

Results:

Anatomic dissections demonstrated muscular confluence spanning the nasal sidewall and upper lip tethering the soft tissue to bone. Thirty-four of 53 chemodenervation patients received perinasal Botox experiencing improvement in synkinetic symptoms of the upper lip, nose, and improved dental show as noted on paired t-test for FGS (p = 0.00096), and FDI social p = 0.015) also supported by naive observer surveys (p = 0.03).

Conclusions:

Human anatomic specimen dissections support a perinasal confluence of musculature with bony attachments that can be successfully treated with chemodenervation in facial synkinesis patients.

Nerve grafts in head and neck reconstruction

PURPOSE OF REVIEW

This article reviews recent literature on repair of peripheral nerve injuries in the head and neck with a focus on autografts, allografts, nerve conduits, and technical considerations.

RECENT FINDINGS

Contemporary nerve grafting techniques offer the potential to improve peripheral nerve outcomes and reduce donor site morbidity. A variety of donor nerves autografts have been described that offer favorable outcomes for segmental reconstruction of facial nerve defects. Recent studies have demonstrated promising results in repair of inferior alveolar nerve injuries with human allografts. Animal models describe successful reinnervation of small defects with neural conduits. The latest data do not favor protocolled nerve graft polarity or use of a motor versus sensory donor nerves.

SUMMARY

Interposition nerve grafting is the gold standard for repair of peripheral nerve injuries when a tension-free primary neurorrhaphy is not possible. Autografts are the work-horse for the majority of head and neck neural defects, however, can result in some degree of donor site morbidity. Recent developments in allografting and neural conduits have the potential to further diversify the head and neck reconstructive surgeon's armamentarium. It is unclear if nerve graft makeup or polarity affect functional outcome.

Facial Reanimation and Reconstruction of the Radical Parotidectomy

Radical parotidectomy may result from treating advanced parotid malignancies invading the facial nerve. Survival is often enhanced with multimodality treatment protocols, including postoperative radiation therapy. In addition to the reconstructive challenge of restoring facial nerve function, patients may be left with a significant cervicofacial concavity and inadequate skin coverage. This should be addressed with stable vascularized tissue that is resistant to radiation-induced atrophy. This article describes a comprehensive strategy, includes the use of the anterolateral thigh free flap, the temporalis regional muscle transfer, motor nerve to vastus lateralis grafts, nerve to masseter transfer, and fascia lata grafts for static suspension.

Strategies to Improve Cross-Face Nerve Grafting in Facial Paralysis

Cross-face nerve grafting enables the reanimation of the contralateral hemiface in unilateral facial palsy and may recover a spontaneous smile. This chapter discusses various clinically applicable strategies to increase the chances for good functional outcomes by maintaining the viability of the neural pathway and target muscle, increasing the number of reinnervating nerve fibers and selecting functionally compatible donor nerve branches. Adopting those strategies may help to further improve patient outcomes in facial reanimation surgery.

Clinical Studies and Pre-clinical Animal Models on Facial Nerve Preservation, Reconstruction, and Regeneration Following Cerebellopontine Angle Tumor Surgery-A Systematic Review and Future Perspectives

Background and purpose: Tumorous lesions developing in the cerebellopontine angle (CPA) get into close contact with the 1st (cisternal) and 2nd (meatal) intra-arachnoidal portion of the facial nerve (FN). When surgical damage occurs, commonly known reconstruction strategies are often associated with poor functional recovery. This article aims to provide a systematic overview for translational research by establishing the current evidence on available clinical studies and experimental models reporting on intracranial FN injury.

Methods: A systematic literature search of several databases (PubMed, EMBASE, Medline) was performed prior to July 2020. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. Included clinical studies were reviewed and categorized according to the pathology and surgical resection strategy, and experimental studies according to the animal. For anatomical study purposes, perfusion-fixed adult New Zealand white rabbits were used for radiological high-resolution imaging and anatomical dissection of the CPA and periotic skull base.

Results: One hundred forty four out of 166 included publications were clinical studies reporting on FN outcomes after CPA-tumor surgery in 19,136 patients. During CPA-tumor surgery, the specific vulnerability of the intracranial FN to stretching and compression more likely leads to neurapraxia or axonotmesis than neurotmesis. Severe FN palsy was reported in 7 to 15 % after vestibular schwannoma surgery, and 6% following the resection of CPA-meningioma. Twenty-two papers reported on experimental studies, out of which only 6 specifically used intracranial FN injury in a rodent (n = 4) or non-rodent model (n = 2). Rats and rabbits offer a feasible model for manipulation of the FN in the CPA, the latter was further confirmed in our study covering the radiological and anatomical analysis of perfusion fixed periotic bones.

Conclusion: The particular anatomical and physiological features of the intracranial FN warrant a distinguishment of experimental models for intracranial FN injuries. New Zealand White rabbits might be a very cost-effective and valuable option to test new experimental approaches for intracranial FN regeneration. Flexible and bioactive biomaterials, commonly used in skull base surgery, endowed with trophic and topographical functions, should address the specific needs of intracranial FN injuries.

The application of venous nerve conduit trap in the immediate repair and reconstruction of facial nerve in parotid gland tumor: an attempt of a new technique

OBJECTIVE

To introduce the application of venous nerve conduit in the immediate repair and reconstruction of facial nerve in parotid gland tumor.

METHODS

Three patients with parotid gland tumor in Sichuan Provincial Cancer Hospital were reviewed. All patients were found that the tumor encased and invaded the facial nerve which was difficult to be separated during the operation when all patients were treated with facial nerve repair and reconstruction with the venous nerve conduit trapping technique.

RESULTS

After 1-year follow-up, all patients recovered well in facial nerve function.

CONCLUSION

The venous nerve conduit trapping technique is an effective attempt in the immediate repair and reconstruction of facial nerve in parotid gland tumor, but it needs to be further confirmed by multiple studies.

Assessment of Tactile Sensitivity Threshold Using Cochet-Bonnet Esthesiometer and Semmes-Weinstein Monofilaments and Their Use in Corneal Neurotization

PURPOSE

Although the Cochet-Bonnet esthesiometer (CBE) measures corneal sensitivity, it has heretofore only been tested on the index pulp. Tactile skin sensitivity thresholds are measured with Semmes-Weinstein monofilaments (SWM). This study measured skin sensitivity thresholds in healthy individuals using CBE and SWM, and compared both instruments in territories involved in corneal neurotization.

METHODS

Overall, 27 healthy individuals were tested by a single examiner at 9 territories on the face, neck, forearm, and leg, using 20-thread SWM and CBE with a diameter of 0.12 mm. Both sides were tested. Thresholds were compared for both instruments and between the different territories using Bayesian methods.

RESULTS

Mean sensitivity levels for SWM ranged from 0.010 to 1.128 g, while mean sensitivity levels for CBE ranged from 0.006 to 0.122 g. Thresholds measured with SWM were significantly higher than with CBE. Both instruments demonstrated higher thresholds in the leg territory than the forearm. However, the forearm presented higher thresholds than the head territories. No significant differences were found between the head territories themselves. Overall, right-side territories exhibited lower thresholds than left-side territories.

CONCLUSIONS

We have reported the first mapping of skin sensitivity thresholds using CBE. Thresholds measured with CBE and SWM were coherent. The use of CBE on the skin is particularly relevant to the field of corneal neurotization.

The sternohyoid muscle flap for new dynamic facial reanimation technique: Anatomical study and clinical results

BACKGROUND

Long-term facial nerve palsy has a highly negative impact on patients' quality of life. In 2016, Alam reported one case of facial reanimation with the sternohyoid muscle after publishing a preclinical study in 2013. Despite the potentially ideal characteristics of this muscle for reanimation of facial palsy, this technique is still not widely used. The objective of our description of cases was to present the clinical results obtained with the surgical procedure and the study on cadavers to confirm the anatomical findings.

METHODS

This work describes the anatomical study of the vascular and nervous pedicle of the sternohyoid muscle compared with clinical results from a series of patients with long-term facial paralysis who underwent facial reanimation between June 2016 and September 2019, through the insertion of the sternohyoid muscle into the masseteric nerve.

RESULTS

The anatomical study was conducted in eight human hemi-necks. In five cases (62%), the vascular pedicle was provided by the superior thyroid artery, and the entrance of the ansa cervicalis to the muscle was constant 1.8 cm from the distal insertion. This series included ten patients who underwent the surgery technique of facial reanimation using the sternohyoid muscle, with a 90% (n = 9) of reinnervation; 100% (n = 10) of flaps were viable, and none of the patients showed complications in the donor area.

CONCLUSIONS

The sternohyoid muscle showed itself as a reliable muscle as a free flap in facial reanimation, and alternative to the gracilis flap. The surgical technique was safe, without any complications, with excellent excursion, recovery, and aesthetic results.

A New Neurorehabilitative Postsurgery Intervention for Facial Palsy Based on Smile Observation and Hand-Mouth Motor Synergies

Objective

To perform a preliminary test of a new rehabilitation treatment (FIT-SAT), based on mirror mechanisms, for gracile muscles after smile surgery.

Method

A pre- and postsurgery longitudinal design was adopted to study the efficacy of FIT-SAT. Four patients with bilateral facial nerve paralysis (Moebius syndrome) were included. They underwent two surgeries with free muscle transfers, one year apart from each other. The side of the face first operated on was rehabilitated with the traditional treatment, while the second side was rehabilitated with FIT-SAT. The FIT-SAT treatment includes video clips of an actor performing a unilateral or a bilateral smile to be imitated (FIT condition). In addition to this, while smiling, the participants close their hand in order to exploit the overlapped cortical motor representation of the hand and the mouth, which may facilitate the synergistic activity of the two effectors during the early phases of recruitment of the transplanted muscles (SAT). The treatment was also aimed at avoiding undesired movements such as teeth grinding. Discussion. Results support FIT-SAT as a viable alternative for smile rehabilitation after free muscle transfer. We propose that the treatment potentiates the effect of smile observation by activating the same neural structures responsible for the execution of the smile and therefore by facilitating its production. Closing of the hand induces cortical recruitment of hand motor neurons, recruiting the transplanted muscles, and reducing the risk of associating other unwanted movements such as teeth clenching to the smile movements.

Hypoglossal and Masseteric Nerve Transfer for Facial Reanimation: A Systematic Review and Meta-Analysis

Background: Hypoglossal and masseteric nerve transfer are currently the most popular cranial nerve transfer techniques for patients with facial paralysis. The authors performed a systematic review and meta-analysis to compare functional outcomes and adverse effects of these procedures. Methods: A review of online databases was performed to include studies with four or more patients undergoing hypoglossal or masseter nerve transfer without muscle transfer or other cranial nerve transposition. Facial nerve outcomes, time to reinnervation, and adverse events were pooled and studied. Results: A total of 71 studies were included: 15 studies included 220 masseteric-facial transfers, and 60 studies included 1312 hypoglossal-facial transfers. Oral commissure symmetry at rest was better for hypoglossal transfer (2.22 ± 1.6 mm vs. 3.62 ± 2.7 mm, p = 0.047). The composite Sunnybrook Facial Nerve Grading Scale was better for masseteric transfer (47.7 ± 7.4 vs. 33.0 ± 6.4, p < 0.001). Time to first movement (in months) was significantly faster in masseteric transfer (4.6 ± 2.6 vs. 6.3 ± 1.3, p < 0.001). Adverse effects were rare (<5%) for both procedures. Conclusions: Both nerve transfer techniques are effective for facial reanimation, and the surgeon should consider the nuanced differences in selecting the correct procedure for each patient.

Neuromotor Speech Recovery Across Different Behavioral Speech Modifications in Individuals Following Facial Transplantation

Despite signs of facial nerve recovery within a few months following face transplantation, speech deficits persist for years. Behavioral speech modifications (e.g., slower-than-normal speaking rate and increased loudness) have shown promising potential to enhance speech intelligibility in populations with dysarthric speech. However, such evidence-based practice approach is lacking in clinical management of speech in individuals with facial transplantation. Because facial transplantation involves complex craniofacial reconstruction and facial nerve coaptation, it is unknown to what extent individuals with face transplant are capable of adapting their motor system to task-specific articulatory demands. The purpose of this study was to identify the underlying articulatory mechanisms employed by individuals with face transplantation in response to speech modification cues at early and late stages of neuromotor recovery. In addition, we aimed to identify speech modifications that conferred improved speech clarity. Participants were seven individuals who underwent full or partial facial vascularized composite allografts that included lips and muscles of facial animation and were in early (~2 months) or late (~42 months) stages of recovery. Participants produced repetitions of the sentence “Buy Bobby a puppy” in normal, fast, loud, and slow speech modifications. Articulatory movement traces were recorded using a 3D optical motion capture system. Kinematic measures of average speed (mm/s) and range of movement (mm³) were extracted from the lower lip (± jaw) marker. Two speech language pathologists rated speech clarity for each speaker using a visual analog scale (VAS) approach. Results demonstrated that facial motor capacity increased from early to late stages of recovery. While individuals in the early group exhibited restricted capabilities to adjust their motor system based on the articulatory demands of each speech modification, individuals in the late group demonstrated faster speed and larger-than-normal range of movement for loud speech, and slower speed and larger-than-normal range of movement for slow speech. In addition, subjects in both groups showed overreliance on jaw rather than lip articulatory function across all speech modifications, perhaps as a compensatory strategy to optimize articulatory stability and maximize speech function. Finally, improved speech clarity was associated with loud speech in both stages of recovery.

Progress in facial reinnervation

Facial nerve injury often results in facial paralysis, which seriously affects the patients both aesthetically and functionally. Facial nerve reinnervation methods, including direct anastomosis, nerve graft, nerve transposition, cross-facial nerve graft, and combined surgeries, have recently become a hot topic with many new procedures being explored. This study summarizes the relevant literatures and discusses the scope of application, advantages, and disadvantages of the different methods. The treatment options or combined surgeries for facial nerve reinnervation should be individualized for specific patients to achieve the best reanimation outcome with good static symmetry, facial tone, and spontaneous, natural, symmetrical, and strong facial movements.

Masseter nerve-based facial palsy reconstruction

Facial paralysis is a devastating disease, the treatment of which is challenging. The use of the masseteric nerve in facial reanimation has become increasingly popular and has been applied to an expanded range of clinical scenarios. However, appropriate selection of the motor nerve and reanimation method is vital for successful facial reanimation. In this literature review on facial reanimation and the masseter nerve, we summarize and compare various reanimation methods using the masseter nerve. The masseter nerve can be used for direct coaptation with the paralyzed facial nerve for temporary motor input during cross-facial nerve graft regeneration and for double innervation with the contralateral facial nerve. The masseter nerve is favorable because of its proximity to the facial nerve, limited donor site morbidity, and rapid functional recovery. Masseter nerve transfer usually leads to improved symmetry and oral commissure excursion due to robust motor input. However, the lack of a spontaneous, effortless smile is a significant concern with the use of the masseter nerve. A thorough understanding of the advantages and disadvantages of the use of the masseter nerve, along with careful patient selection, can expand its use in clinical scenarios and improve the outcomes of facial reanimation surgery.

Facial nerve management in patients with malignant skull base tumors

INTRODUCTION

The course of the facial nerve through the cerebellopontine angle, temporal bone, and parotid gland puts the nerve at risk in cases of malignancy. In contrast to Bell's palsy, which presents with acute facial paralysis, malignancies cause gradual or fluctuating weakness.

METHODS

We review malignancies affecting the facial nerve, including those involving the temporal bone, parotid gland, and cerebellopontine angle, in addition to metastatic disease. Intraoperative management of the facial nerve and long term management of facial palsy are reviewed.

RESULTS

Intraoperative management of the facial nerve in cases of skull base malignancy may involve extensive exposure, mobilization, or rerouting of the nerve. In cases of nerve sacrifice, primary neurorrhaphy or interposition grafting may be used. Cranial nerve substitution, gracilis free functional muscle transfer, and orthodromic temporalis tendon transfer are management options for long term facial paralysis.

CONCLUSION

Temporal bone, parotid gland, and cerebellopontine angle malignancies pose a tremendous risk to the facial nerve. When possible, the facial nerve is preserved. If the facial nerve is sacrificed, static and dynamic reanimation strategies are used to enhance facial function.

Facial nerve transfer for facial reanimation with parotidoplasty approach

BACKGROUND

Facial paralysis has a profound impact on quality of life in affected individuals, primarily through loss of verbal and nonverbal communication. Common facial nerve reanimation techniques include coaptation to the masseteric or hypoglossal nerve. Most techniques require nerve grafts to achieve a tension-free neurorrhaphy. Our report aims to show a surgical adaption to current facial reanimation procedures using a partial parotidoplasty approach in order to avoid challenges caused by interpositional nerve grafts through primary neurorrhaphy.

PATIENTS AND METHODS

The modified surgical approach was performed on four patients, aged 30-67. Length of paralysis ranged from 6 to 13 months. Cause of paralysis included one patient with Bell's palsy in one patient, prior surgery in two patients, and traumatic fracture in the remaining patient. A modified Blair approach is used to expose the parotid capsule. The facial nerve is dissected proximally toward the stylomastoid foramen and distally toward the masseter. The parotid gland substance is sectioned overlying each branch of the facial nerve using ultrasonic dissection or hemostatic scalpel, allowing mobilization of the proximal segment and upper and lower divisions of the facial nerve. The superficial lobe of the parotid is preserved in most cases. The House-Brackmann (H-B) functional scale was used to assess facial nerve function pre- and post-operatively.

RESULTS

All patients showed H-B score V or greater prior to reanimation. Follow-up was conducted at 3-, 6-, and 12-months in all patients with resultant improvement of H-B scores of I in three patients and II in the remaining patient. Only one complication was noted, with one patient developing a right postauricular hematoma that was adequately managed without sequelae. All remaining patients experienced an uncomplicated post-operative course.

CONCLUSION

Our modified approach to facial nerve reanimation works well with a planned parotidoplasty allowing for successful reanimation outcomes without the need for interpositional grafting. This technique may be considered in masseteric and hemi-hypoglossal nerve transfers for the reinnervation of facial muscles.

Predicting Resting Oral Commissure Tone Outcomes Following Masseter Nerve Transfer in Facial Reanimation

Objective: To quantify the degree of oral commissure resting tone improvement in patients undergoing masseter to facial nerve transfer. Methods: A retrospective cohort study was completed in a tertiary academic medical practice. Consecutive cases of masseter nerve transfer patients within a patient database were evaluated from 6/2012 to 9/2017. Inclusion criteria were patients >18 years of age, with complete unilateral paralysis, receiving a masseter to facial nerve transfer, with at least 12 months of recovery, and possessing complete pre- and postoperative data. Patients were excluded if a simultaneous adjunctive procedure was performed so that tone could not be attributed to masseter transfer alone. The main outcome measure was the facial asymmetry index (FAI): the measured difference in distance between the medial canthus and oral commissure of the healthy and paralyzed sides. Results: Twenty-nine patients met inclusion and exclusion criteria and were further analyzed for this study. The oral commissure symmetry improved from 4.7 ± 2.8 mm preoperatively to 2.2 ± 2.3 mm postoperatively. In multivariate analysis, the preoperative FAI was the only significant predictive factor for improvement in commissure symmetry at rest (r = 0.589). This suggests that for each 1.0 mm of worse preoperatively oral commissure asymmetry, the improvement postoperatively was 0.6 mm. Age, gender, body mass index, side of paralysis, duration of paralysis, and recipient branch of facial nerve were not significant predictors in a multivariate analysis. Conclusion: Masseter to facial nerve transfer yields an estimated 60% correction in the oral commissure asymmetry. This estimation may be helpful in determining if adjunctive procedures should be utilized.

Early Outcomes in an Emerging Facial Nerve Center: The Oregon Health and Science University (OHSU) Experience

OBJECTIVES

Nerve transfer (NT) and free gracilis muscle transfer (FGMT) are procedures for reanimation of the paralyzed face. Assessing the surgical outcomes of these procedures is imperative when evaluating the effectiveness of these interventions, especially when establishing a new center focused on the treatment of patients with facial paralysis. We desired to discuss the factors to consider when implementing a facial nerve center and the means by which the specialist can assess and analyze outcomes.

METHODS

Patients with facial palsy secondary to multiple etiologies, including cerebellopontine angle tumors, head and neck carcinoma, and trauma, who underwent NT or FGMT between 2014 and 2019 were included. Primary outcomes were facial symmetry and smile excursion, calculated using FACE-gram and Emotrics software. Subjective quality of life outcomes, including the Facial Clinimetric Evaluation (FaCE) Scale and Synkinesis Assessment Questionnaire (SAQ), were also assessed.

RESULTS

14/22 NT and 6/6 FGMT patients met inclusion criteria having both pre-and postoperative photo documentation. NT increased oral commissure excursion from 0.4 mm (SD 5.3) to 2.9 mm (SD 6.8) (P = 0.05), and improved symmetry of excursion (P < 0.001) and angle (P < 0.001). FGMT increased oral commissure excursion from -1.4 mm (SD 3.9) to 2.1 mm (SD 3.7), (P = 0.02), and improved symmetry of excursion (P < 0.001). FaCE scores improved in NT patients postoperatively (P < 0.001).

CONCLUSIONS

Measuring outcomes, critical analyses, and a multidisciplinary approach are necessary components when building a facial nerve center. At our emerging facial nerve center, we found NT and FGMT procedures improved smile excursion and symmetry, and improved QOL following NT in patients with facial palsy secondary to multiple etiologies.

Acute Peripheral Facial Palsy: Recent Guidelines and a Systematic Review of the Literature

BACKGROUND

This study reviews recent literature on facial palsy guidelines and provides systematic reviews on related topics of interest.

METHODS

An electronic database search was performed to identify recent guidelines dealing with facial nerve palsy, systematic reviews and recent meta-analysis published between 2011 and 2019 (inclusive). The literature search used the search terms "Bell's palsy," "Ramsay-Hunt syndrome," "Facial palsy," "Facial paralysis," "Facial paresis," "Guideline," "Meta-analysis," "Systematic review," and "Randomized controlled trial." Only studies written in English were used.

RESULTS

The characteristics of treatment trends for facial palsy have been reviewed over the past decade. The most prominent change noted may be the shift from the conventional House-Brackmann facial nerve grading system to the Sunnybrook and eFACE systems. In addition, the results of serial meta-analyses indicate increasing agreement with the use of surgical decompression of the facial nerve. Beyond steroids or combined steroid-antiviral treatment, various novel drugs and treatments have been tried. For long-standing facial paralysis and postparetic synkinesis sequelae after facial palsy, facial reanimation has been highlighted and the necessity of new paradigms have been raised.

CONCLUSION

For peripheral facial paralysis, various changes have been made, not only in the facial nerve grading systems, but also in medical treatments, from surgical procedures to rehabilitation, during the last decade.

Masseteric-zygomatic nerve transfer for the management of eye closure-smile excursion synkinesis

OBJECTIVE

The purpose of this study is to illustrate the efficacy of masseteric-to-zygomatic nerve transfer to address eye closure-smile excursion synkinesis after facial nerve paralysis.

BACKGROUND

Synkinesis after facial nerve paralysis represents a wide range of facial movement disability. One manifestation is involuntary smiling with eye closure and a concomitant reduction of oral commissure movement with attempted smile ("frozen smile") - arising as a result of aberrant fibers populating the zygomatic branch-muscle complex. This is a particularly difficult area to treat with conservative management. We propose a single-stage procedure to sever the dysfunctional zygomatic nerve and perform a masseteric-zygomatic nerve coaptation to recover a voluntary smile.

METHODS

We present a case series of eight patients with eye closure/smile excursion synkinesis who underwent single-stage masseteric-zygomatic nerve transfer by a single surgeon. The surgical technique and indications for surgery were reviewed. Patients underwent facial movement analysis using Emotrics.

RESULTS

We analyzed the pre- and post- surgical photographic images of 8 patients with synkinesis (7 female, 1 male). Masseteric-facial nerve transfer was performed from 18 months to 22 years after the initial facial paralysis. Eyelid and brow positioning were more symmetric after surgery, with discrepancy between affected and unaffected side decreasing from 2.1 to 1.0 mm (p < .05) and 1.74 to 1.29 mm (p < .05), respectively. Symmetry of smile excursion postoperatively was also improved with commissure excursion discrepancy decreasing from 8.8 to 3.78 mm (p < .05). Discrepancy in the smile angle when comparing affected to unaffected side improved postoperatively from 10.3 to 5.2 degrees (p < .05). Improvement in oral commissure height was noted, but not statistically significant.

CONCLUSIONS

The masseteric-zygomatic nerve transfer is a useful technique for the treatment of eye closure/smile excursion synkinesis after failure of chemodenervation and/or physical therapy.

Changes in Electrical Activity of the Masseter Muscle and Masticatory Force after the Use of the Masseter Nerve as Donor in Facial Reanimation Surgery

Introduction  The masseter nerve has been used as a donor nerve for facial reanimation procedures due to the multiple advantages it offers; it has been generally considered that sacrifice of the masseter nerve does not alter the masticatory apparatus; however, there are no objective studies to support this claim. Objective  To evaluate the impact that the use of the masseter nerve in dynamic facial reconstruction has on the electrical activity of the masseter muscle and on bite force. Materials and Methods  An observational and prospective longitudinal study was performed measuring bite force and electrical activity of the masseter muscles before and 3 months after dynamic facial reconstructive surgery using the masseter nerve. An occlusal analyzer and surface electromyography were employed for measurements. Results  The study included 15 patients with unilateral facial paralysis, with a mean age of 24.06 ± 23.43. Seven patients were subjected to a masseter-buccal branch nerve transfer, whereas in eight patients, the masseter nerve was used as a donor nerve for gracilis free functional muscle transfer. Electrical activity of the masseter muscle was significantly reduced after surgery in both occlusal positions: from 140.86 ± 65.94 to 109.68 ± 68.04 ( p = 0.01) in maximum intercuspation and from 123.68 ± 75.64 to 82.64 ± 66.56 ( p = 0.01) in the rest position. However, bite force did not show any reduction, changing from 22.07 ± 15.66 to 15.56 ± 7.91 ( p = 0.1) after the procedure. Conclusion  Masseter nerve transfer causes a reduction in electromyographic signals of the masseter muscle; however, bite force is preserved and comparable to preoperative status.

Contemporary Concepts of Primary Dynamic Facial Nerve Reconstruction in the Oncologic Patient

Transection of the facial nerve and its branches during extensive ablative procedures in the oncologic patient causes loss of control of facial mimetic muscles with severe functional and aesthetic sequelae. In such patients with advanced tumorous disease, copious comorbidities, and poor prognosis, rehabilitation of the facial nerve has long been considered of secondary priority. However, recent advances in primary facial nerve reconstruction after extensive resection demonstrated encouraging results focusing on rapid and reliable restoration of facial functions. The authors summarize 3 innovative approaches of primary dynamic facial nerve reconstruction by using vascularized nerve grafts, dual innervation concepts, and intra-facial nerve transfers.