Amer's classification of territories of facial nerve injury in early cases and strategies for the management of different territories.

Early cases of facial nerve injury are best treated by restoring the neural pathway to the same existing facial muscles. Knowledge of the exact territory of facial nerve injury is required to design a plane for the reconstruction of these injuries and to compare results. The current study aims to design a classification system for territories of facial nerve injury based on the location of nearest healthy fascicles to the site of injury both proximally and distally. Two hundred-one patients with early facial nerve injury were assessed for treatment. According to the results of the exploration, 13 territories of injury were identified. The management strategy was planned according to the territory of injury. The current classification system is a simple, easy and effective method for the classification of territories of facial nerve injury. The classification system accurately describes the nearest possible healthy proximal and distal fascicles and can be employed to easily report cases and implement a management plan. This classification scheme also allows us to more effectively compare results.

Outcomes of Facial Symmetry and Tone at Rest After Masseteric-to-Facial Nerve Transfer.

Importance: Masseteric-to-facial nerve transfer has gained popularity as a technique that provides dynamic voluntary function in unilateral facial paralysis. Despite the multiple studies that have demonstrated its efficiency in restoring dynamic facial function, there is a paucity of data on the effects on facial symmetry and tone at rest. Objective: To evaluate facial symmetry and tone at rest after masseteric-to-facial nerve transfer in patients with unilateral facial paralysis. Design, Setting, and Participants: This is a retrospective review of patients undergoing masseteric-to-facial nerve transfer for unilateral facial nerve paralysis at a tertiary academic center from 2012 to 2016. Patient demographics, etiology and duration of facial nerve paralysis, intervention, and the electronic Facial Assessment by Computer Evaluation (eFACE) scores were analyzed. Intervention: Masseteric-to-facial nerve transfer. Main Outcomes and Measures: Resting facial symmetry and tone was graded preoperatively and postoperatively using eFACE. Results: The study included 11 patients with complete unilateral facial paralysis treated with masseteric-to-facial nerve transfer from 2012 to 2016. Postoperative eFACE scores across the dynamic midface and smile scores demonstrated a statistically significant increase compared with preoperative eFACE scores (p < 0.001). There was no statistically significant difference found between preoperative and postoperative static midface and smile eFACE scores. Conclusions: Masseteric-to-facial nerve transfer has demonstrated promising results in restoration of voluntary smile. However, it has little to no effect on resting facial symmetry and tone.

Advances in facial nerve management in the head and neck cancer patient.

PURPOSE OF REVIEW: The purpose of this review is to summarize best practices in facial nerve management for patients with head and neck cancer. In addition, we provide a review of recent literature on novel innovations and techniques in facial reanimation surgery. RECENT FINDINGS: Although recommended when tumor ablation surgery requires facial nerve sacrifice, facial reanimation procedures are not always performed. Concurrent dynamic facial reanimation with masseteric nerve transfers and cable graft repair can preserve native facial muscle function. Static suspension can provide facial support and immediate resting symmetry for patients. Eyelid weight and eye care should not be delayed, particularly in patients with trigeminal sensory deficits. Choice of neural source to innervate a gracilis-free muscle transfer for smile reanimation remains controversial; however, new techniques, such as dual innervation and multivector muscle transfer, may improve aesthetic and functional outcomes. SUMMARY: Management of the facial nerve in the setting of head and neck cancer presents unique challenges. When possible, simultaneous oncologic resection and facial reanimation is ideal given the open surgical field, newly dissected and electrically stimulatable facial nerve branches, as well as minimizing postoperative healing time to prevent postsurgical treatment delays. A coordinated approach to facial nerve management with a multidisciplinary surgical team may help provide optimal, comprehensive care.

Powering the Gracilis for Facial Reanimation: A Systematic Review and Meta-analysis of Outcomes Based on Donor Nerve.

Importance: Free gracilis transfer for dynamic reanimation in chronic facial paralysis is the gold standard, but there remains a need to better understand outcomes with respect to the donor nerve. Objective: To characterize outcomes in adults undergoing primary gracilis transfer for facial paralysis stratified by donor nerve used for neurotization. Data Sources: Search strategies were used in Ovid MEDLINE (1946-2019), Embase (1947-2019), Scopus (1823-2019), Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov (1997-2019). Study Selection: Inclusion and exclusion criteria were designed to capture studies in adults with unilateral chronic facial paralysis undergoing single-paddle free gracilis transfer. All study types were included except case reports. Abstracts and full texts were reviewed in duplicate. Of 130 unique citations, 10 studies including 295 patients were included after applying inclusion and exclusion criteria. Data were analyzed between November 2018 and December 2019. Data Extraction and Synthesis: PRISMA guidelines were followed. The Newcastle-Ottawa scale was used to assess study quality, and the Cochrane Risk of Bias tool was used to assess risk of bias. Independent extraction by 2 authors (P.M.V. and J.J.C.) was performed. Data were pooled using a random-effects model. Main Outcomes and Measures: Owing to heterogeneity in reporting of facial reanimation outcomes, we first performed a systematic review, and then compiled available outcomes for meta-analysis. Outcomes studied for meta-analysis were oral commissure excursion and facial symmetry. Results: Meta-analysis of masseteric nerve (MN) (n = 56) vs cross-facial nerve graft (CFNG) (n = 52) in 3 retrospective studies showed no statistical heterogeneity between these studies (I2 = 0%), and the standardized mean difference (SMD) was greater for MN (0.55; 95% CI, 0.17 to 0.94). Meta-analysis of angles of symmetry in 2 retrospective studies comparing MN (n = 51) to CFNG (n = 47) both at rest (-0.22; 95% CI, -0.63 to 0.18) and with smiling (-0.14; 95% CI, -0.73 to 0.46) were better with MN, though the difference was not statistically significant. Conclusions and Relevance: Owing to heterogeneity in reported outcomes from facial reanimation, we were unable to make definitive conclusions regarding the optimal donor nerve. Establishing a reporting standard at peer-reviewed journals to improve results reporting is one method to allow for improved collaboration in the future. Standardizing follow-up times, assessing spontaneity in an objective and reproducible fashion, and use of consistent outcome measures would allow for future meta-analyses and better understanding of options for facial reanimation.

Orbicularis Oculi Muscle Reinnervation Confers Corneal Protective Advantages over Static Interventions Alone in the Subacute Facial Palsy Patient.

BACKGROUND: Corneal protection is a priority in flaccid facial palsy patients. Denervation of the orbicularis oculi muscle results in weak palpebral closure and predisposes patients to severe corneal sequelae. While periorbital static procedures enhance corneal coverage in repose, voluntary closure is only regained through dynamic reinnervation of the muscle. This study aims to elucidate the added effect of dynamic reinnervation of the orbicularis oculi muscle on long-term corneal integrity as well as on dynamic closure of the palpebral aperture. METHODS: Retrospective review was performed on two groups of complete palsy patients: those who received solely periorbital static procedures and those who underwent concomitant orbicularis oculi muscle reinnervation and static lid procedures. Only patients with complete ophthalmic examinations were included. Corneal punctate epithelial erosions in addition to static and dynamic palpebral measurements were serially assessed preoperatively and postoperatively. RESULTS: Of 272 facial palsy patients, 26 fit the inclusion criteria. Eleven patients underwent combined muscle reinnervation involving facial-to-masseteric nerve coaptation in addition to static eye procedures, and 15 patients underwent solely static interventions. Analysis revealed a 65.3 percent lower mean punctate epithelial erosion score in reinnervation patients as compared with static patients when evaluated at more than 9 months postoperatively (p < 0.01). Reinnervation patients were also found to have 25.3 percent greater palpebral aperture closure (p < 0.05) and 32.8 percent higher closure velocity (p < 0.01) compared with static patients. CONCLUSION: In patients with subacute facial palsy, dynamic reanimation of the orbicularis oculi muscle with concomitant static interventions provides lasting corneal protection not seen in patients who receive solely static interventions. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Dual Coaptation of Facial Nerve Using Masseteric Branch of Trigeminal Nerve for Iatrogenic Facial Palsy: Preliminary Reports.

OBJECTIVES: Immediate facial nerve substitution or graft technique has been used for the repair of facial nerve defects occurring as a result of tumour dissection. However, some patients report unsatisfactory outcomes, such as difficulty in maintaining resting or smiling symmetry, due to persistent flaccid facial palsy. Here we evaluated the functional outcomes of transferring the masseteric branch of the trigeminal nerve to the facial nerve adjunct to facial nerve graft. METHODS: We reviewed the medical records of seven patients who underwent facial reanimation surgery between 2014 and 2016. The patients were divided into two groups according to the type of facial reanimation surgery: group A, masseteric nerve innervation with interposition graft; group B, interposition graft only. The postoperative resting symmetry and dynamic movement were compared. RESULTS: Facial contraction was first observed in group A at 4 months and in group B at 7.3 months. Most of the patients achieved reliable resting symmetry; however, one patient in group B exhibited unsatisfactory facial weakness on the affected side. Group A patients showed better dynamic movement than group B patients. Eye closure, oral excursion and oral continence were better in group A than in group B patients. Smile symmetry in both groups was similar due to hyperkinetic movement in group A patients and flaccidity in group B patients. CONCLUSIONS: Dual innervation of the masseteric branch of the trigeminal nerve improves the dynamic movement of paralysed facial muscles and shortens the recovery period in patients with iatrogenic facial palsy.

The Inferior Alveolar Nerve: To Graft or Not to Graft in Ablative Mandibular Resection?

PURPOSE: To determine contemporary surgical decision-making processes regarding the use of a nerve graft with ablative mandibular resection and to identify utilization barriers among head and neck surgeons. MATERIALS AND METHODS: An online electronic survey that queried practice patterns and subjective opinions regarding inferior alveolar nerve (IAN) grafting at the time of mandibular resection was distributed to head and neck surgeons and oral and maxillofacial surgery residency program directors (N = 249) by use of REDCap. RESULTS: The response rate was 37%. Only 10.6% of respondents perform IAN reconstruction "always" (60% "usually" or "sometimes" and 28.8% "rarely" or "never") with ablative benign mandibular resection, whereas only 1.1% perform IAN grafting always (10-20% usually or sometimes and 89% rarely or never) with ablative malignant mandibular resection. Among the 93 participants, the most important utilization barriers were lack of evidence for improving quality of life, potential impact of radiation on nerve healing, and lack of efficacy for restoration of neurosensory function. CONCLUSIONS: Despite evidence-based literature showing the efficacy of immediate IAN grafting with ablative benign mandibular resection, most head and neck surgeons do not perform this procedure routinely in patients with benign or malignant mandibular pathology. Future research should focus not only on the achievement of functional sensory recovery but also on the impact of IAN grafting on improved quality-of-life indicators in both benign and malignant mandibular disease, with and without adjunctive chemoradiation therapy.

Anatomical study of the masseteric and obturator nerves: Application to face transplant and reanimation procedures.

The masseteric nerve (MN) and the anterior branch of the obturator nerve (ON) that innervate the transferred gracilis muscle have proved highly efficient for reanimating paralyzed facial muscles when muscle transfer is required. Previous researchers have published the total axonal load for myelinated fibers in both nerves. However, the real motor axonal load has not been established. We performed the study on 20 MN and 13 ON. The segments of the MN and the ON were embedded in paraffin, sectioned at 10 µm, and stained following a standard immunohistochemical procedure using anti-choline acetyltransferase to visualize the motor fibers. The MN has a higher axonal load than the ON. There were statistically significant differences between the axonal load of the proximal segment of the MN and the ON. These findings confirm that end-to-end anastomoses between the MN and the ON should preferably use the proximal segment. However, MN neurotomy should ideally be performed between the proximal and distal segments, preserving innervation to the deep fascicles. Our results show that the MN is ideal as a donor motor nerve for reinnervating transplanted muscle for dynamic reanimation of the paralyzed face. The neurotomy should ideally be performed between the first and second collateral branches of the MN. Clin. Anat. 32:612-617, 2019. © 2019 Wiley Periodicals, Inc.

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

IMPORTANCE: A review of the role of masseteric nerve transfer is needed to guide its use in facial reanimation. OBJECTIVE: To systematically review the available literature, and, when applicable, analyze the combined outcomes of masseteric nerve transfer to better define its role in reanimation and to guide further research. DATA SOURCES: Two independent researchers conducted the review using PubMed-NCBI and Scopus literature databases for studies on masseteric nerve transfer for facial nerve paralysis. STUDY SELECTION: Studies that examined masseter nerve transfer with additional cranial nerve transposition/coaptation or muscle flap were excluded. DATA EXTRACTION AND SYNTHESIS: Literature review and data extraction followed established PRISMA guidelines. Two researchers extracted data independently. MAIN OUTCOMES AND MEASURES: The main planned outcomes for the study were quantitative results of facial nerve movement after nerve transfer including oral commissure movement and time to nerve recovery. RESULTS: A total of 13 articles met inclusion criteria with a total of 183 patients undergoing masseteric nerve transfer. From those studies, there were a total of 183 patients who underwent masseteric nerve transfer. There were 85 men and 98 women with a mean (SD) age of 43 (12.2) years and mean (SD) follow up examination after surgery of 22 (7.6) months. Mean (SD) duration of nerve paralysis was 14 (6) months. Most common cause of paralysis was cerebellopontine angle tumors (81%). Six studies coapted the masseteric nerve to the main facial nerve trunk, whereas 7 used distal branches (buccal or zygomatic). Four studies used interposition nerve grafts with great auricular nerve. Two measures, improvement in oral commissure excursion and length from reanimation to facial movement, were measured consistently across the studies. Pooled analysis showed time from surgery to first facial movement, described in 10 studies, to be 4.95 months (95% CI, 3.66 to 6.24). Distal branch coaptation improved time to recovery vs main branch coaptation, 3.76 vs 5.76 months (95% CI, -0.33 to 4.32), but mean difference was not significant. The use of interposition graft significantly delayed time of nerve recovery, 6.24 vs 4.06 months (95% CI, 0.20 to 4.16). When controlled for main trunk coaptation only, interposition nerve graft delayed recovery but difference was no longer statistically significant, 6.24 vs 4.75 months (95% CI, -0.94 to 3.92). Reported complications were minor and rare occurring in only 6.5% (12 of 183) of patients. CONCLUSIONS AND RELEVANCE: The masseteric nerve was found to be a good option for nerve transfer in this patient population, and showed favorable results in both time to nerve recovery and improvement in oral commissure excursion. LEVEL OF EVIDENCE: NA.

Differential Reanimation of the Midface and Lower Face Using the Masseteric and Hypoglossal Nerves for Facial Paralysis.

BACKGROUND: Hypoglossal nerve transfer is frequently employed to reanimate the paralyzed facial muscles after irreversible proximal facial nerve injury. However, it can cause significant postoperative synkinesis because it involves the reinnervation of the whole mimetic musculature using a single motor source. OBJECTIVE: To describe our experience with differential reanimation of the midface and lower face using separate motor sources in patients with short-term facial paralysis after brain surgery. METHODS: Seven patients underwent combined nerve transfer (the masseteric nerve to the zygomatic branch and the hypoglossal nerve to the cervicofacial division of the facial nerve) and cross-facial nerve grafting with the aim of achieving a spontaneous smile. The median duration of paralysis before surgery was 7 mo and follow-up ranged from 7 to 31 mo (mean: 18 mo). For evaluation, both physical examination and video analysis were performed. RESULTS: In all patients, reanimation of both the midface and the lower face was successful. A nearly symmetrical resting lip was achieved in all patients, and they were able to voluntarily elevate the corners of their mouths without visible synkinesis and to close their eyes while biting. No patient experienced impairment of masticatory function or tongue atrophy. CONCLUSION: Differential reanimation of the midface and lower face with the masseteric and hypoglossal nerves is an alternative method that helps to minimize synkinetic mass movement and morbidity at the donor site.

The masseteric nerve: a versatile power source in facial animation techniques.

The masseteric nerve has many advantages including low morbidity, its proximity to the facial nerve, the strong motor impulse, its reliability, and the fast reinnervation that is achievable in most patients. Reinnervation of a neuromuscular transplant is the main indication for its use, but it has been used for the treatment of recent facial palsies with satisfactory results. We have retrospectively evaluated 60 patients who had facial animation procedures using the masseteric nerve during the last 10 years. The patients included those with recent, and established or congenital, unilateral and bilateral palsies. The masseteric nerve was used for coaptation of the facial nerve either alone or in association with crossfacial nerve grafting, or for the reinnervation of gracilis neuromuscular transplants. Reinnervation was successful in all cases, the mean (range) time being 4 (2-5) months for facial nerve coaptation and 4 (3-7) months for neuromuscular transplants. Cosmesis was evaluated (moderate, n=10, good, n=30, and excellent, n=20) as was functional outcome (no case of impairment of masticatory function, all patients able to smile, and achievement of a smile independent from biting). The masseteric nerve has many uses, including in both recent, and established or congenital, cases. In some conditions it is the first line of treatment. The combination of combined techniques gives excellent results in unilateral palsies and should therefore be considered a valid option.

A comparison of one- versus two-stage surgery in an experimental model of functional muscle transfer with interposed nerve grafting.

Functional muscle transfer (FMT) combined with cross-facial nerve grafting (CFNG) is the gold standard treatment of chronic unilateral facial palsy, performed by most surgeons over two operative stages to minimise FMT denervation atrophy. Proponents of one-stage surgery cite shorter total recovery time, fewer operative procedures and a possible beneficial neurotrophic effect of muscle attachment. This study aimed to compare one- and two-stage surgery in terms of neural and muscle reinnervation and FMT force production. Forty New Zealand white rabbits underwent one- or two-stage rectus femoris FMT and interposed nerve grafting under different reinnervation conditions. For two-stage surgery, nerve grafting was followed by FMT after three months and by final experiments after a further six months, whereas one-stage groups experienced nerve grafting and FMT together and final experiments after nine months. Outcomes compared were nerve graft and rectus nerve morphometry, FMT reinnervation measured using PGP 9.5, and FMT force production. Statistical analysis was performed by means of the independent samples t-test or the Mann-Whitney Rank Sum test using Statistics Package for the Social Sciences version 11.0.4 for Mac OS X. Nerve graft reinnervation was similar for respective one- and two-stage surgery groups or favoured one-stage surgery. There was no significant difference between respective groups in terms of rectus nerve morphometry, muscle reinnervation, or absolute, weight-adjusted or weight- and control-adjusted tetanic force production. One-stage surgery offers potential advantages including a reduction in the number of surgical procedures, a shorter total recovery time and beneficial economic and healthcare delivery implications. This data supports previous clinical and experimental studies and questions the basis for performing facial reanimation by FMT combined with CFNG over two separate operative stages.

[An experimental study on regeneration of the inferior alveolar nerve after lyophilized nerve homografting in the rabbit].

This study was designed to evaluate the differences between the regenerative process in cases of autogenous nerve grafting and lyophilized homologous nerve grafting. Rabbit inferior alveolar nerves (10 mm lengths) were resected and replaced with lyophilized homologous segments from the sciatic nerve. On the opposite side, the resected nerves were autogenously grafted. The experimental subjects were divided into autogenous nerve-graft and the lyophilized nerve-graft groups. Results. 1. Regenerating axons appeared in the autogenous-graft group 2 weeks after the operation and 4 weeks after the operation in the homografted lyophilized group. The difference in regeneration between the 2 groups was significant. 2. Regenerating axons in the autogenously grafted nerves made contact with remaining Schwann cells and endneural tubes. Axons in the homografted lyophilized nerves invaded along newly infiltrated Schwann cells and empty tube skeletal structures. The number of regenerating axons from outside the skeletal structure was greater than the number of regenerating axons from inside the skeletal structure. 3. In the case of autogenous grafting, nerve fibers of diameters greater than 3 microns increased 66.7% after 24 weeks; the corresponding figure for homografted lyophilized nerves was 48.4%. 4. In instances of autogenous grafting, 16 weeks after surgery, the ratio of distal proximal myelinated nerve fibers had grown. In cases of homografted lyophilized nerves, this tendency to increase continued until the twenty-fourth postsurgical week. 5. In both groups, it remained possible to record nerve action potentials 12 weeks after surgery. The sensory nerve conduction velocity of autogenously grafted nerves increased gradually to approach control values 24 weeks after surgery. That of homografted lyophilized nerves recovered more slowly. 6. Increases in number of nerve fibers with a diameter of more than 3 microns were proportional to the rate at which sensory nerve conduction velocity recovered.

[Horizontal osteotomy of the body of the mandible with transfer of the inferior dental nerve]. / Ostéotomie horizontale du corps de la mandibule avec transfert du nerf dentaire inférieur.

By patient with developmental face asymmetry resulting from unilateral mandibular hyperplasia, irregular height of the mandibular body was strongly manifested on affected side. Since a large portion of inferior border of the mandible predicted to be cutted off contained almost the whole of the lower alveolar nerve, transfer of this last was employed. The nerve was surgically isolated along its course, and secured by being lifted while horizontal osteotomy of mandibular body was performed. Next the nerve was accommodated in new groove created in a safe distance from the roots of lower teeth. Postoperative healing was uneventful, but feeling in the region of lower lip was decreased during a few days immediately after surgery. Patient reexamined 18 months later demonstrated satisfactory esthetic and functional result with preserved feeling in the region supplied by the lower alveolar nerve.

Peripheral nerve grafts to the frog optic tectum: a morphological study of the axon reaction in trigeminal motor and sensory neurons.

The mandibular branch of the trigeminal nerve was severed and the proximal stump was grafted onto the optic tectum in adult Rana pipiens. The resultant changes occurring in the cell bodies of origin in the ipsilateral trigeminal motor and mesencephalic nuclei were studied qualitatively and quantitatively. Nucleolar, nuclear, and somal cross-sectional areas increased in size significantly approximately 3 days after surgery and peaked at 6 weeks postsurgery. This swelling, in which the nucleolus was most severely affected, gradually reversed itself and disappeared by 24 weeks after surgery. Despite the cell enlargement, cytoplasmic basophilia was maintained or even slightly increased. These morphologic changes suggest a strong anabolic reaction. Two differences were found between the motoneurons and the sensory neurons. First, the morphometric cell changes occurred at a faster rate in neurons of the trigeminal motor nucleus than in those of the mesencephalic nucleus. The time course of the motoneuron response correlated well with that of axonal regeneration from the nerve graft. Second, there was a delayed loss of mesencephalic nucleus cells between 12 and 24 weeks after surgery, whereas cells of the trigeminal motor nucleus were maintained at all survival times studied. Taken together with sensory cell loss in the trigeminal ganglion, this suggests a greater viability of regenerating motoneurons.

Effect of the perineurial vascular net on experimental grafting of the inferior alveolar nerve.

For optimum nerve repair, it is imperative that free autogenous nerve grafts be used in cases when peripheral nerve loss is great. This study was performed to determine the influence of the perineurial vascular net on nerve regeneration in such grafts. It was concluded that nerve grafting is more likely to be successful if suturing of the epineurium and perineurium is precise and if a dense vascular net in the recipient bed, but not around the graft, is retained.

Comparison of suture methods and materials in experimental inferior alveolar nerve grafting.

Currently, peripheral nerve defects are being treated successfully by microsurgical techniques using autogenous nerve transplantations and synthetic suture materials. This paper describes the influence of various suture methods and materials on nerve repair as experimentally evaluated in rabbits. The results show that the action potentials of the nerves anastomosed with polyglycolic acid sutures recovered faster than those anastomosed with nylon.