Single-Stage Facial Reanimation in the Surgical Treatment of Unilateral Established Facial Paralysis

Composite Sterno-Omohyoid Functional Muscle Transfer for Dual-Vector Smile Reanimation: A Case Series

Background: Facial reanimation flaps often add bulk and produce single-vector smiles, and multivector flaps frequently require challenging intramuscular dissection. Objective: To evaluate the effectiveness of sterno-omohyoid flap (SOHF) transfer for dual-vector smile reanimation by measuring upper dental show and oral commissure movement. Methods: SOHF transfers from 2017 to 2020 were retrospectively evaluated using eFACE and Emotrics software. Results: Four patients with flaccid and one with nonflaccid facial paralysis were identified (four females and one male, median age: 39 years (range: 38-65); two acoustic neuromas, two congenital, one temporal bone fracture). Median follow-up was 20 months (range: 14-26). All flaps received masseteric nerves and two had additional cross-face grafts. Four developed contraction [median time to contraction: 5.5 months (range: 3-10)]. Mean oral commissure excursion and dental exposure improvements were 7.6 ± 4.0 mm (p = 0.03) and 2.9 ± 1.8 mm (p = 0.05), respectively. Dynamic, smile, and midface-smile eFACE improvements were 20.3 ± 6.8 (p = 0.007), 25.5 ± 14.5 (p = 0.03), and 50.5 ± 12.0 mm (p = 0.004) points, respectively. Mean SOHF mass was 14 ± 1.7 g. Conclusion: The SOHF is a small flap that provides dual-vector smile reanimation in flaccid and nonflaccid facial paralysis.

Facial surface electromyography: A systematic review on the state of the art and current perspectives

PURPOSE

Peripheral facial nerve palsy is a severely disabling condition. In current clinical practice, the commonest tools to assess facial palsy are grading scales, digital face image analyses or facial muscle electrophysiology. However, these techniques suffer from subjectivity or invasiveness and cannot be applied as part of a routine clinical assessment. Therefore, novel non-invasive office-based tools are needed. Surface electromyography (sEMG) may potentially fulfill the requirements of objectivity, low examiner-dependence, and minimal invasiveness. The aim of this systematic review is to define the state of the art on the use of sEMG for facial nerve functional assessment.

MATERIALS AND METHODS

Pubmed, Scopus and Web of Science databases were systematically searched. The study protocol was registered on PROSPERO in January 2023. The review was conducted according to the PRISMA guidelines.

RESULTS

After the application of inclusion-exclusion criteria, 15 manuscripts with adequate relevance to this topic were included in the review.

CONCLUSIONS

Facial sEMG represents a potentially useful tool to implement objective quantification of facial nerve function in clinical practice. Given the heterogeneity of methods and analysis in the available studies, sEMG results are hardly comparable. The introduction of methodological guidelines, followed by large prospective studies on well-defined subsets of patients with facial nerve impairment, is advocated.

Comparison of Outcomes of Smile Reanimation Between Dual- Versus Single-Innervation Technique in Single-Stage Latissimus Dorsi Neuromuscular Transfer in Facial Paralysis Patients

Background: Although a dual-innervation technique has emerged in single-stage functional latissimus dorsi (LD) muscle transfer for smile reanimation, its benefits over conventional techniques have not been elucidated. Objective: To compare outcomes of dual-innervation technique with those of single-innervation. Methods: Patients with facial palsy treated with single-stage functional LD muscle transfer were identified, and categorized into two groups: single and dual innervation. Outcomes were assessed using clinical examination based on the Terzis grading system and using automated software (Emotrics). Results: Fifty-nine patients (mean age 37.6 years; male/female 30/29) were analyzed, including 40 in single (35.1 years, 23/17) and 19 in dual-innervation group (43.0 years, 7/12), with a median follow-up of 34 months (range, 9-165) (single: 41.5, 12-165, dual: 23.0, 9-41). Tumor-related paralysis was the most common etiology in both groups (overall: 45.8%, single: 40.0%, dual: 57.9%). The dual group had a significantly higher rate of cases with Terzis grade IV or V postoperatively. In the Emotrics-based evaluation, the dual group exhibited significantly enhanced improvements in smile excursion in the dynamic state compared with the single. The degree of improvement in the resting state did not differ between groups. Conclusion: The dual-innervation technique might provide promising results in achieving enhanced smile excursion.

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.

Integrated Approaches for Reconstruction of Facial Paralysis

BACKGROUND

Facial paralysis can affect periorbital muscles, oral competence, and facial expressions with significant facial deformities, which could occur in either children or adults with variable severity, duration, and degree of recovery.

OBJECTIVE

The present study was aimed to delineate treatment plans for facial paralysis with different clinical scenarios and to report the results of these patients.

METHODS

Patients were grouped according to different presentations as follows: (1) facial paralysis with incomplete recovery; (2) young patients of facial paralysis without recovery; (3) senile patients of facial palsy without recovery; (4) combined facial palsy with mandibular deficiency, vascularized bone reconstruction for mandible with (a) subsequent muscle transfer or (b) simultaneous sling operation or (c) simultaneous facial nerve exploration and cross nerve grafting; (5) palsy of frontal branch of facial nerve; (6) palsy of zygomatic-buccal branch of facial nerve; (7) palsy of marginal mandibular branch of facial nerve; (8) partial recovery with dyskinesia; and (9) facial paralysis with dynamic asymmetry and muscle atrophy. According to clinical scenarios, different treatment plans were provided, and clinical outcomes were evaluated and presented.

RESULTS

All patient groups achieved fair or satisfactory outcomes. Revisions using sling procedures, botulinum toxin injection, and filler or fat graft as supplement further refined the ultimate outcomes.

CONCLUSIONS

For reconstruction of facial paralysis, individualized integrated treatment plans are mandatory according to the presentation and condition of the patient. Comprehensive considerations and strategic solutions for the existing disabilities have been appreciated by the patients. The least numbers of operations with considerate correction of asymmetry were the major concerns of the patients.

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.

Microsurgical Reconstruction of the Smile: A Critical Analysis of Outcomes

BACKGROUND

Facial paralysis is a significant problem with functional, psychological, and esthetic consequences. Free muscle transfer for reanimation of the smile has been established as the preferred reconstructive method. However, little has been reported on the complications after this procedure. We sought to perform a critical analysis of these complications and their ultimate outcomes.

METHODS

A retrospective review was performed on consecutive patients undergoing microsurgical reconstruction of the smile by the senior author from 2013 through 2017. Patient demographics including age, race, body mass index, and medical comorbidities were recorded. The cause of facial palsy and type of microsurgical reconstruction were assessed. Patient outcomes including complications and management of the complication were analyzed. All statistical analyses were performed using nonparametric analyses.

RESULTS

We identified 17 patients who underwent microsurgical reconstruction of the smile, with 1 patient undergoing bilateral procedures, for a total of 18 microsurgical smile reanimation procedures performed. Sixteen of these were 1-stage reconstructions with the coaptation of the nerve to the masseter, whereas 2 were 2-stage reconstructions using cross-facial nerve grafts. The gracilis muscle was used as the donor muscle in all cases. The patients had a median age of 26.5 and a median follow-up of 1.04 years from surgery. There were no major early complications observed in our cohort. Eight (44.4%) reanimations developed a minor complication that required subsequent reoperation. The reoperations were performed at a median of 0.97 years after the microsurgical procedure. The most common indication for reoperation was lateral retraction of the insertion of the transplanted muscle, which occurred in 5 (62.5%) patients. One patient underwent surgical exploration for an abrupt loss of transplanted muscle function after trauma to the cheek. Another patient had less than expected transplanted muscle activity at 1 year postoperatively and underwent exploration of the cross-facial nerve graft and a neurorrhaphy revision. Lastly, 1 patient developed significant rhytids over the transplanted muscle secondary to tethering of the skin to the underlying muscle. This patient underwent 2 subsequent revisions, with placement of acellular dermal matrix between the muscle and skin and fat grafting. All patients had functional animation of the transplanted muscle postoperatively.

CONCLUSIONS

Complications occurred in 44.4% of patients undergoing microsurgical reanimation of the smile. Most complications were minor in nature and were readily addressed with advancement of the transplanted muscle. All patients in our series had muscle function after the muscle transplantation.

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.

Sterno-omohyoid Free Flap for Dual-Vector Dynamic Facial Reanimation

Background:

Dynamic rehabilitation of longstanding facial palsy with damaged, atrophied, or absent facial muscles requires replacement of neural and muscular components. The ideal reconstruction would include a fast-twitch muscle that is small, a reliable donor vessel and nerve, and the potential to provide a natural, synchronous, dentate smile with minimal donor site morbidity. Many flaps have been successfully used historically, but none has produced ideal rehabilitation.

Objective:

To evaluate the novel sterno-omohyoid, dual-vector flap in rehabilitation of chronic facial paralysis.

Results:

We performed sterno-omohyoid free tissue transfer for smile reanimation in a 39-year-old male with a history of longstanding right facial palsy following resection of a skull base tumor several years previously. We transferred both muscles with the superior thyroid artery, middle thyroid vein, and ansa cervicalis. The patient developed a dynamic smile by 6 months postoperatively, and he had improved objective facial symmetry.

Conclusion:

Herein, we demonstrate the first use of the sterno-omohyoid flap for successful facial reanimation. Overall, it is a novel flap in facial reanimation with many advantages over traditional flaps, including the potential to produce a more synchronous, dynamic smile while adding minimal bulk to the face. Future series will better elucidate the potential of the sterno-omohyoid flap.

Evaluation of Donor Morbidity following Single-Stage Latissimus Dorsi Neuromuscular Transfer for Facial Reanimation

BACKGROUND

Single-stage latissimus dorsi neuromuscular transfer has been a valuable option for dynamic smile reanimation. However, there is a paucity of studies evaluating the potential donor morbidity in such cases. The present study aimed to comprehensively analyze the donor morbidity following functional latissimus dorsi muscle transfer.

METHODS

Patients who underwent single-stage functional latissimus dorsi muscle transfer for smile reanimation between 2002 and 2016 were reviewed. Postoperative complications and functional impairments at the donor sites were evaluated. The Quick-Disabilities of the Arm, Shoulder and Hand questionnaire was used for assessing postoperative donor-site function.

RESULTS

Sixty patients, including 12 pediatric (18 years or younger) patients, were analyzed. Mean length of a harvested thoracodorsal nerve was 14.9 cm. Fourteen patients were treated with a dual innervation technique, in which both a descending and a transverse branch of the thoracodorsal nerve were harvested. Donor complications were observed in seven cases; all of them were seromas and resolved by simple aspiration. No other complications including scoliosis and sensory and/or motor disturbances in the upper extremities were encountered. Fifty patients responded to the Quick-Disabilities of the Arm, Shoulder and Hand questionnaire at a median follow-up of 51 months. The average score was 2.64, and all but three patients scored less than 10. No variables, including patient age (pediatric versus adult) and the use of a dual-innervation technique, affected the donor morbidities, including the functional deficits.

CONCLUSION

Single-stage latissimus dorsi neuromuscular transfer for facial reanimation might be associated with a low rate of complications and minimal functional morbidity at the donor site.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Outcome Tracking in Facial Palsy

Outcome tracking in facial palsy is multimodal, consisting of patient-reported outcome measures, clinician-graded scoring systems, objective assessment tools, and novel tools for layperson and spontaneity assessment. Patient-reported outcome measures are critical to understanding burden of disease in facial palsy and effects of interventions from the patient perspective. Clinician-graded scoring systems are inherently subjective and no 1 single system satisfies all needs. Objective assessment tools quantify facial movements but can be laborious. Recent advances in facial recognition technology have enabled automated facial measurements. Novel assessment tools analyze attributes such as spontaneous smile, emotional expressivity, disfigurement, and attractiveness as determined by laypersons.

Mixed facial reanimation technique to treat paralysis in medium-term cases

Recent facial paralyses, in which fibrillations of the mimetic muscles are still detectable by electromyography (EMG), allow facial reanimation based on giving new neural stimuli to musculature. However, if more time has elapsed, mimetic muscles can undergo irreversible atrophy, and providing a new neural stimulus is simply not effective. In these cases function is provided by transferring free flaps into the face or transposing masticatory muscles to reinstitute major movements, such as eyelid closure and smiling. In a small number of cases, patients affected by paralysis are referred late - more than 18 months after onset. In these cases, reinnervating the musculature carries a high risk of failure because some or all of the mimetic muscles may atrophy irreversibly while axonal ingrowth is taking place. A mixed reanimation technique to address this involves a neurorrhaphy between the masseteric nerve and a facial nerve branch for the orbicularis oculi, to ensure a stronger innervation to that muscle, associated with the transposition of the temporalis muscle to the nasiolabial sulcus. This gives good symmetry in the rest of the midface, while smiling movement is achievable, but not guaranteed. This one-time facial reanimation is particularly indicated for those who refuse major free-flap surgery or when that may be risky, as in previously operated and irradiated fields. More extensive procedures based on utilizing a free flap to recover smiling, while adding a cross-face nerve graft to restore blinking, may be proposed for motivated patients. Between 2010 and 2015, five patients affected by complete unilateral facial palsy underwent this technique in the Maxillofacial Surgery Department, San Paolo Hospital (Milan, Italy). Symmetry of the middle-third of the face at rest and recovery of smiling was quite good. Complete voluntary eyelid closure was obtained in all cases. Combining temporalis flap rotation and a masseteric-to-orbicularis-oculi-facial-nerve branch neurorrhaphy seems to be a valid solution for those medium-term referred patients.

Controversies in Contemporary Facial Reanimation

Facial palsy is a devastating condition with profound functional, aesthetic, and psychosocial implications. Although the complexity of facial expression and intricate synergy of facial mimetic muscles are difficult to restore, the goal of management is to reestablish facial symmetry and movement. Facial reanimation surgery requires an individualized treatment approach based on the cause, pattern, and duration of facial palsy while considering patient age, comorbidities, motivation, and goals. Contemporary reconstructive options include a spectrum of static and dynamic procedures. Controversies in the evaluation of patients with facial palsy, timing of intervention, and management decisions for dynamic smile reanimation are discussed.

Masseteric-facial nerve neurorrhaphy: results of a case series

OBJECTIVE Facial palsy is a well-known functional and esthetic problem that bothers most patients and affects their social relationships. When the time between the onset of paralysis and patient presentation is less than 18 months and the proximal stump of the injured facial nerve is not available, another nerve must be anastomosed to the facial nerve to reactivate its function. The masseteric nerve has recently gained popularity over the classic hypoglossus nerve as a new motor source because of its lower associated morbidity rate and the relative ease with which the patient can activate it. The aim of this work was to evaluate the effectiveness of masseteric-facial nerve neurorrhaphy for early facial reanimation. METHODS Thirty-four consecutive patients (21 females, 13 males) with early unilateral facial paralysis underwent masseteric-facial nerve neurorrhaphy in which an interpositional nerve graft of the great auricular or sural nerve was placed. The time between the onset of paralysis and surgery ranged from 2 to 18 months (mean 13.3 months). Electromyography revealed mimetic muscle fibrillations in all the patients. Before surgery, all patients had House-Brackmann Grade VI facial nerve dysfunction. Twelve months after the onset of postoperative facial nerve reactivation, each patient underwent a clinical examination using the modified House-Brackmann grading scale as a guide. RESULTS Overall, 91.2% of the patients experienced facial nerve function reactivation. Facial recovery began within 2-12 months (mean 6.3 months) with the restoration of facial symmetry at rest. According to the modified House-Brackmann grading scale, 5.9% of the patients had Grade I function, 61.8% Grade II, 20.6% Grade III, 2.9% Grade V, and 8.8% Grade VI. The morbidity rate was low; none of the patients could feel the loss of masseteric nerve function. There were only a few complications, including 1 case of postoperative bleeding (2.9%) and 2 local infections (5.9%), and a few patients complained about partial loss of sensitivity of the earlobe or a small area of the ankle and foot, depending on whether great auricular or sural nerves were harvested. CONCLUSIONS The surgical technique described here seems to be efficient for the early treatment of facial paralysis and results in very little morbidity.

Current thoughts and developments in facial nerve reanimation

PURPOSE OF REVIEW

To present the most current literature regarding the management of acute and chronic facial paralysis. This review will focus primarily on smile reanimation in the setting of acute and chronic facial paralysis. The management of the flaccid and the hypertonic face will be discussed.

RECENT FINDINGS

Recent developments include advances in neural repair with fibrin glue and the use of cadaveric nerve grafts as interposition grafts. Advances in nerve substitutes have been shown to limit donor-site morbidity and provide similar outcomes to autografts. Techniques for muscle transfer continue to evolve to improve smile outcomes.

SUMMARY

The goal of facial reanimation surgery is to restore meaningful facial movement. The goal should be to have quality-driven clinical practice guidelines to better facilitate patient care. This process must be initiated by facial reanimation surgeons deciding to use consistent outcome measures to report their results. Currently, it is impossible to make a direct comparison between different surgical techniques because of inconsistent methods of evaluation. Despite the lack of consistent quantitative evaluation, there have been many exciting advances in the field.

Thoracodorsal nerve graft for reconstruction of facial nerve branching

OBJECT

Surgical treatment of parotid malignancies may frequently involve facial nerve amputation to achieve oncological radical resection. The entire facial nerve branching from its exit from the stylomastoid foramen to the periphery of the gland is often sacrificed. The first reconstructive strategy is the immediate reconstruction of the facial nerve by directly anastomosing the trunk of the facial nerve to its distal branches by interpositional nerve grafting. The present study was performed to determine the adequacy of thoracodorsal nerve grafting for immediate repair of the facial nerve. The anatomical features of the thoracodorsal nerve make it particularly appropriate to match its trunk to the stump of the facial nerve at its exit from the stylomastoid foramen. Up to seven branches of the thoracodorsal nerve may be distally anastomosed to the severed distal branches of the facial nerve. More complex reconstruction may be addressed simultaneously by contemporary harvesting a de-epithelialized free flap from the same site based on thoracodorsal vessel perforators and preparing a rib graft from the same donor site.

METHODS

Between October 2003 and August 2010, seven patients affected by parotid tumors (6 with parotid malignancies and 1 with multiple recurrences of pleomorphic adenoma) underwent radical parotidectomy with intentional sacrifice of the facial nerve to obtain oncological radical resection. In all patients, the facial nerve was reconstructed with an interpositional thoracodorsal nerve graft. In four patients, a de-epithelialized free flap based on the latissimus dorsi was transposed to cover soft tissue defects. Moreover, two of these patients also required a rib graft to reconstruct both the condyle and ramus of the mandible. With the exception of one patient affected by recurrent pleomorphic adenoma, all patients underwent radiotherapy after surgical treatment.

RESULTS

All patients in our study recovered mimetic facial function. Facial muscles showed clinical signs of recovery within 5-14 (mean: 7.8) months, with varying degrees of mimetic restoration, and almost complete facial symmetry at rest in all patients. The House-Brackmann final score was I in two patients, II in two patients, and III in three patients.

CONCLUSIONS

A thoracodorsal nerve graft to replace extratemporal facial nerve branching is a valid alternative technique to multiple classical nerve grafts, with good matching at both the proximal and distal anastomoses.

Muscle reinnervation in one or two stages?: experimental study in rats with end-to-side nerve graft

PURPOSE: To compare muscle reinnervation in one and two surgical stages using end-to-side neurorrhaphy (ESN) without donor nerve injury. METHODS: The experiment was performed on four groups of 20 rats. Group 1 (G1), one stage, received the graft which was sutured to the tibial nerve, with ESN, and its free stump was sutured end-to-end to the distal stump of the sectioned peroneal nerve (PN), all in the same operation. In Group 2 (G2), two stages, the nerve graft was sutured to the tibial nerve, with ESN. Two months later the PN was sectioned and its distal stump connected to the distal stump of the graft as in G1. Normal control group (Gn) received the graft only sutured to the tibial nerve, with ESN. Denervated control group (Gd), as well received the graft and had the PN sectioned and its two stumps buried in adjacent musculature, with the aim of denervating the cranial tibial muscle (CTM), the target of this study. The parameters used to evaluate CTM reinnervation were muscle mass, muscle fiber's minimum diameter and area. RESULTS: The mean CTM mass, the average of the muscular fibers areas and the average of the muscular fiber minimum diameters was higher (all p<0.0001) in G2 than in G1. Comparing the four groups, these parameters had their maximum expression in Gn and the minimum in Gd, as expected. CONCLUSION: The two stages showed better muscle reinnervation than one stage.

Double innervation in free-flap surgery for long-standing facial paralysis

OBJECTIVE

One-stage free-flap facial reanimation may be accomplished by using a gracilis transfer innervated by the masseteric nerve, but this technique does not restore the patient's ability to smile spontaneously. By contrast, the transfer of the latissimus dorsi innervated by the contralateral facial nerve provides the correct nerve stimulus but is limited by variation in the quantity of contraction. The authors propose a new one-stage facial reanimation technique using dual innervation; a gracilis muscle flap is innervated by the masseteric nerve, and supplementary nerve input is provided by a cross-face sural nerve graft anastomosed to the contralateral facial nerve branch.

METHODS

Between October 2009 and March 2010, four patients affected by long-standing unilateral facial paralysis received gracilis muscle transfers innervated by both the masseteric nerve and the contralateral facial nerve.

RESULTS

All patients recovered voluntary and spontaneous smiling abilities. The recovery time to voluntary flap contraction was 3.8 months, and spontaneous flap contraction was achieved within 7.2 months after surgery. According to Terzis and Noah's five-stage classification of reanimation outcomes, two patients had excellent outcomes and two had good outcomes.

CONCLUSIONS

In this preliminary study, the devised double-innervation technique allows to achieve a good grade of flap contraction as well as emotional smiling ability. A wider number of operated patients are needed to confirm those initial findings.

MicroRNA-1 and microRNA-206 improve differentiation potential of human satellite cells: a novel approach for tissue engineering of skeletal muscle

Innovative strategies based on regenerative medicine, in particular tissue engineering of skeletal muscle, are promising for treatment of patients with skeletal muscle damage. However, the efficiency of satellite cell differentiation in vitro is suboptimal. MicroRNAs are involved in the regulation of cell proliferation and differentiation. We hypothesized that transient overexpression of microRNA-1 or microRNA-206 enhances the differentiation potential of human satellite cells by downregulation quiescent satellite cell regulators, thereby increasing myogenic regulator factors. To investigate this, we isolated and cultured human satellite cells from muscle biopsies. First, through immunofluorescent analysis and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), we showed that in satellite cell cultures, low Pax7 expression is related to high MyoD expression on differentiation, and, subsequently, more extensive sarcomere formation, that is, muscle differentiation, was detected. Second, using qRT-PCR, we showed that microRNA-1 and microRNA-206 are robustly induced in differentiating satellite cells. Finally, a gain-of-function approach was used to investigate microRNA-1 and microRNA-206 potential in human satellite cells to improve differentiation potential. As a proof of concept, this was also investigated in a three-dimensional bioartificial muscle construct. After transfection with microRNA-1, the number of Pax7 expressing cells decreased compared with the microRNA-scrambled control. In differentiated satellite cell cultures transfected with either microRNA-1 or microRNA-206, the number of MyoD expressing cells increased, and α-sarcomeric actin and myosin expression increased compared with microRNA-scrambled control cultures. In addition, in a three-dimensional bioartificial muscle construct, an increase in MyoD expression occurred. Therefore, we conclude that microRNA-1 and microRNA-206 can improve human satellite cell differentiation. It represents a potential novel approach for tissue engineering of human skeletal muscle for the benefit of patients with facial paralysis.

Modern concepts in facial nerve reconstruction

Background

Reconstructive surgery of the facial nerve is not daily routine for most head and neck surgeons. The published experience on strategies to ensure optimal functional results for the patients are based on small case series with a large variety of surgical techniques. On this background it is worthwhile to develop a standardized approach for diagnosis and treatment of patients asking for facial rehabilitation.

Conclusion

A standardized approach is feasible: Patients with chronic facial palsy first need an exact classification of the palsy's aetiology. A step-by-step clinical examination, if necessary MRI imaging and electromyographic examination allow a classification of the palsy's aetiology as well as the determination of the severity of the palsy and the functional deficits. Considering the patient's desire, age and life expectancy, an individual surgical concept is applicable using three main approaches: a) early extratemporal reconstruction, b) early reconstruction of proximal lesions if extratemporal reconstruction is not possible, c) late reconstruction or in cases of congenital palsy. Twelve to 24 months after the last step of surgical reconstruction a standardized evaluation of the therapeutic results is recommended to evaluate the necessity for adjuvant surgical procedures or other adjuvant procedures, e.g. botulinum toxin application. Up to now controlled trials on the value of physiotherapy and other adjuvant measures are missing to give recommendation for optimal application of adjuvant therapies.